Building On Science: My Career (So Far) In Cell Research p. 46

Transcription

Building On Science:
My Career (So Far)
In Cell Research p. 46
ISSN: 1913-1925 2016 VOL 9 ISSUE 1
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CONTENTS
FOREWORD
14 From David to Goalith:
Past, Present, and Future of the
Foundation by B.Tang
ARTICLES
Bioscience
17 The Role of MicroRNA-449 in
Human Breast Cancer by A. Shah
22 Planarian Regeneration in
Response to Drug Disruption of
the Wnt and MAPK Pathways
by Y. Shen, T. Etheridge, E. Hsu,
S. Kaushal
Environmental Science
28 Effectiveness and toxicity of oil
spill reagents on Artemia Salina
by N. A. Sharma
Physical Sciences &
Mathematics
32 Single Note Dissonance
Through Harmonic SelfInterference by M. Ng
SCIENCE FROM
THE SOURCE
40 The Deep Roots of the Rocky
Mountains: Geophysical Studies
of Western Canada by C.A. Currie
47 Building on Science: My
Career (So Far) in Cell Research
by J. Parreno
TEACHING
RESOURCES
49 The Water Project by S. Popp
ARTS AND
SCIENCE
51 Introducing the Arts and
Science Section by C. Yan &
A. Lam
INSIGHTS
53 The Science of Tears
by M. Agarwal
54 Proton Therapy: A New Tool
for Treating Cancer by L. Pang
57 Heat Vision: Superman or PitBearing Snakes? by J. Baek
59 Me, Myself, and the Universe
by K. Zhang
FOREWORD
From David to Goliath: Past, Present, and Future of the Foundation
I have witnessed the greatest growth in the history of our organization, from a local journal to a national
presence, over the past four years. It has been an honour to be a part of this transformation. I am constantly
humbled by the enthusiasm, talent, and passion of students involved with the Foundation for Student
Science and Technology.
Today, the Foundation provides multiple platforms to develop the career potential of students. The Journal
remains our cornerstone and longest standing tradition. However, we constantly strive for innovation with
novel sections such as Teaching Resources and InSights. The online Research Co-op has evolved into
a unique opportunity for high school students to engage in research. The Program has gone from pilot to
province-wide in just three short years. To date, more than 180 students across Ontario have worked with
over 100 science mentors on fascinating topics ranging from genomics to cryptography, computer science
to quantum physics, and psychosocial oncology to indigenous health history. The Ambassador program
complements these opportunities by promoting them broadly across Canada. The Foundation is a platform
for students to help other students, collectively providing experiences that help to launch careers.
Our organization puts students in leadership positions where they can affect positive change. My volunteer
work has helped me discover a passion for innovation in education, so much so that I hope to integrate this
interest into my future career as a physician. Students in the Foundation spearhead our organization’s every
accomplishment, from developing curricula used across Ontario to broadening the audience of our journal to
the international level.
In a few short years, the Foundation has evolved into a nationwide force promoting student potential and
education. We have an even brighter future ahead and more importantly, so do the students across Canada
who we serve.
Sincerely,
Brandon is a medical student at the University of Toronto with a background in basic science
research and extensive experience developing educational programs at local, provincial,
and national levels. He majored in Biology and Psychology at McMaster University where he
graduated first in his class. By taking graduate level courses in systems leadership during
medical school, Brandon hopes to gain new perspective on the healthcare system. He has
been involved with the Foundation for the past four years and is currently the Section Editor of
the novel Teaching Resources section of JSST. He aspires to unite his passions for teaching,
education, and medicine through a career as a physician educator.
Brandon Tang
Teaching Resources Section Editor | Journal of Student Science and Technology
MD Candidate 2018 | University of Toronto
Email | [email protected]
Twitter | @DrBrandonTang
ARTICLES
THE ROLE OF MICRORNA-449 IN HUMAN BREAST CANCER
Ajay Shah
University of St. Andrews College Gate, St Andrews, KY16 9AJ, Fife, Scotland, United Kingdom
ABSTRACT
According to the Canadian Cancer Society, an estimated 25 220 cases of breast cancer were diagnosed in Canada
and 5 060 of these cases were expected to be fatal in 2015. Current treatment options are often very invasive,
harmful, and ineffective. The purpose of this experiment was to mitigate tumour growth by manipulation of microRNA (mRNA) levels. The mRNAs are small molecules that code for proteins, and levels of specific mRNAs are
deregulated in cancer cells. In this experiment, levels of micro-RNA 449, which is deregulated in breast cancer
cell lines, were returned to their baseline levels. Numerous tests were then conducted to test the viability of the
resulting cells. Replicable experiments showed that the strength, motility and invasiveness of the breast cancer
cells was greatly diminished after mRNA-449 levels returned to baseline levels. Furthermore, research indicated
that 4 potential genes (CRIP2, XBP1, TAF4B, and SFXN2) can be manipulated in future experiments to further
diminish the viability of the breast cancer tumours.
En 2015, 25220 cas estimés de cancer du sein ont été diagnostiqués au Canada et 5060 de ces cas étaient prévus
d’être fatales. Les options de traitement courantes sont souvent très envahissantes, nuisibles et inefficaces. L’objet
de cette expérience était d’atténuer la croissance de la tumeur en manipulant les niveaux d’ARN-Micro. ARNm sont
de petites molécules qui codent pour des protéines et en cellules de cancer, les niveaux de certains ARNms sont
dérégulés. Les niveaux d’ARN-micro 449, qui sont dérégulés dans les lignées cellulaires de cancer du sein, ont été
retournées à leurs niveaux de base dans cette expérience. La viabilité des cellules ainsi obtenues a été analysé
par plusieurs tests. Les expériences reproductibles ont indiqué que la force, la mobilité et le caractère invasif des
cellules de cancer du sein ont été diminués après que les niveaux d’ARN-micro 449 sont retournés à leurs niveaux
de base. En outre, l’étude a révélé que quatre gènes potentiels (CRIP2, XBP1, TAF4B, et SFXN2) pourraient être
manipulés à l’avenir pour réduire davantage la viabilité des tumeurs du cancer du sein.
KEY WORDS
microRNA-449; deregulation; breast cancer; anti-miR; microRNA knockdown
INTRODUCTION
Breast cancer is currently one of the most prevalent
forms of cancer, comprising up to 26% of newly
diagnosed cancer cases (Canadian Cancer Society,
2016). Treatment options include chemotherapy,
radiation therapy and invasive surgery (Carlson et al.,
2009). None of these treatment options are successful
100% of the time, and many alternative therapies are
currently being researched by scientists (Carlson et al.,
2009).
MicroRNAs (miRNAs), are small RNAs that are around
20–22 nucleotides long, and have been found to
contribute to a number of cellular processes including
stem cell self-renewal and differentiation of embryonic
stem cells (Liu & Tang, 2011). In a previous miRNA
profiling study using a set of lymph node negative (LNN)
breast cancer samples, several miRNAs, including
miR-449a, were found to be deregulated (Foekens et
al., 2008).
DOI: 10.13034 / JSST-2016-001
The miR-449 family (a, b and c) has been shown to be a
potent inducer of cell death, cell cycle arrest, and/or cell
differentiation by several studies done in the past (Lizé
et al., 2011). In the current study the role of miR-449a in
breast cancer cells will be tested. We hypothesized that
the upregulation or downregulation of miR-449a back
to baseline levels would decrease cancer cell viability.
MATERIALS AND METHODS
The methods used in this experiment were designed
to measure levels of microRNA-449 in each cell line,
then return it to baseline levels. After doing so, multiple
Invasion/Migration assays were conducted to measure
cell viability and motility. Finally, a PCR was conducted
to identify possible gene targets for future research.
THE JOURNAL OF STUDENT SCIENCE AND TECHNOLOGY
2016 VOL 9
ISSUE 1
13
Quantitative
Reverse
Transcriptase
Real-time
Polymerase Chain Reaction (qRT-PCR) to identify
levels of microRNA-449 in breast cancer cell lines
MicroRNA expression was assessed by qRT-PCR
analysis using TaqMan® microRNA Assays (Applied
Biosystems, CA, USA). This assay includes a reverse
transcription (RT) step using the TaqMan® MicroRNA
Reverse Transcription Kit (Applied Biosystems, CA,
USA) wherein a stem-loop RT primer specifically
hybridizes to a miRNA molecule, reverse transcribed
with a MultiScribe reverse transcriptase, and then
analyzed using the Applied Biosystems 7900 HT RealTime PCR system.
RESULTS
MiR-449 Knock-Down and Up-Regulation
T47D cells were transfected using a 50nM concentration of anti-miR-449 (Applied Biosystems) and
Lipofectamine™ RNAiMax transfection reagent (Life
Technologies) as per manufacturers’ protocols. MDAMB-468 cells were similarly transfected with premiR-449 (Applied Biosystems). The anti-miR was
designed to lower miR-449 to baseline levels in cell
lines that had upregulated levels. Similarly, the pre-miR
intended to upregulate miR-449 in cell lines that had the
molecule underexpressed.
MiR-449 is non-predictably regulated in cancer cells
In comparison to a healthy breast cell line (MCF-10A),
a qRT-PCR showed that miR-449 can be severely
underexpressed or overexpressed, indicating that it
could potentially be a trigger for oncogenesis (Figure 1).
MTS Assay
The viability of T47D and MDA-MB-468 were examined
using the CellTiter 96® Non-Radioactive Cell Proliferation
Assay (MTS), according to the manufacturer’s protocol
(Promega).
Cell Migration and Invasion Assay
The movement of cells from one area to another
and the ability of malignant tumor cells to invade
normal surrounding tissue were measured using the
CytoSelect™ 24-Well Cell Migration and Invasion
Assay (8 µm, Fluorometric Format) following the
manufacturer’s protocol (Cell Biolabs).
Quantitative
Reverse
Transcriptase
Real-time
PCR (qRT-PCR) to identify genes correlated with
microRNA-449
Another qRT-PCR and reverse transcription (RT)
analysis was performed using TaqMan® microRNA
Assay (Applied Biosystems, CA, USA) and TaqMan®
MicroRNA Reverse Transcription Kit (Applied
Biosystems, CA, USA) respectively. These were to
assess various gene expression levels in breast cancer
cells.
14
2016 VOL 9
ISSUE 1
The experimental results showed that after miR-449
levels were returned to baseline, the viability and motility
of breast cancer cells are decreased.
qRT-PCR showed deregulated miR-449 levels in cancer
cells
A qRT-PCR showed that miR-449 was up-regulated
in patients with tumours (p = 0.0042), specifically
recurrent tumours (p = 0.003). This could indicate
that the deregulation of miR-449 contributes to the
aggressiveness and invasiveness of the breast cancer
tumour cells.
Restoring miR-449 to baseline levels decreases
invasiveness
After the cell lines were transfected with the anti-miR,
Migration/Invasion assays were conducted on two of
the treated cancer lines (T47D, MDA-MB-231B), and
compared to an untreated group of cells from the same
line. The cells treated with anti-miR-449 were shown to
have reduced migration and invasion abilities, indicating
that this treatment could reduce the aggressiveness of
these tumours (Figure 2, Figure 3). Specifically, the
MDA-MB-231B cell line’s invasive properties were
severely inhibited by anti-miR treatment (Figure 3).
Several genes were identified as targets of miR-449a
An in silico analysis was carried out with the predicted
targets of the microRNA, correlated with data from in
vitro studies in the Gene Expression Omnibus database.
This analysis identified four genes (SFXN2, TAF4B,
XBP1, CRIP2) that were predicted targets, correlated in
breast cancer, and downregulated by miR-449a (Figure
4).
PCR analysis of identified genes in breast cancer cell
lines
Each of the four genes were found to have a role in
cell development and a qRT-PCR was conducted to
compare baseline levels (in MCF-10A) to levels in the
other cancer cell lines. For the most part, it was found
that the genes were severely upregulated in the breast
cancer lines (Figure 5).
LA REVUE POUR LES ÉTUDIANTS EN TECHNOLOGIE ET SCIENCES
DOI: 10.13034 / JSST-2016-001
DISCUSSION
Recent studies show that miR-449a,b and c can induce
cell death, cell cycle arrest and cell differentiation (Lizé
et al., 2011). It plays an important role in cell function,
but also to avoid cancer (Lizé et al., 2011). The
experiments in this project were specifically designed
to test whether returning miR-449 levels back to normal
(either upregulation or downregulation, depending on
how it was deregulated in each cell line) would affect the
oncogenic cells. It was hypothesized that returning to
baseline levels would cause a decrease in cell viability.
It appears that treatment of the cells lines with anti-miR
or pre-miR does in fact appear to decrease the viability
of the cell lines. Anti-miR interferes with microRNA by
physically blocking or cleaving the molecules, while
Pre-miR increases miR function by providing precursor
molecules that are taken up into cells and modified
(Stenvang et al., 2012). It was hypothesized that
by allowing microRNA-449 to function as usual, the
molecule may be able to trigger cell death or cell cycle
arrest through its signaling pathways.
The results showed that regulating miR-449 primarily
affects the motility and invasiveness of the cancer
cells, especially when compared to an untreated group
of the same cell line. Computed cell counting showed
that the anti-miR treatment was significant in inhibiting
invasiveness in two of the cancer cell groups.
By searching through pre-existing databases (primarily
the Gene Expression Omnibus Database), it was found
that 4 genes are anti-correlated with the miR-449a
levels in oncogenic cells. The target genes, SFXN2,
TAF4B, XBP1and CRIP2 could all play some role in
breast cancer, and several have potentially oncogenic
properties.
Pre-existing literature indicated that XBP1 is one of
two genes that are often co-expressed in human
breast carcinomas (Dery et al). TAF4B is reported to
be overexpressed in stem cells, but levels decrease
after cells differentiate - thus denoting a correlation
between the gene and cell differentiation (Baha et al).
CRIP2 is found to have apoptosis promoting effects
in esophageal cancer cells (Lo et al). The genes were
all upregulated in the cancer cell lines, and may have
oncogenic properties that identify them as future targets
for genetic treatment. Further tests should be done to
identify other potential targets of miR-449.
DOI: 10.13034 / JSST-2016-001
The primary limitation of this research would be
the difficulty in translating these results to practical
treatments. Although this treatment has shown positive
in vitro results, implementing it in human or animal
species would require extensive research. However,
the field of microRNA is still relatively nascent, and
showing a tangible link between these molecules and
cancer cells is significant.
CONCLUSION
The regulation of miR-449 has shown promising
results with a number of cell lines. In the future, further
understanding of the effects of this molecule and
correlated genes may be a step toward finding an
efficient breast cancer treatment. First of all, treatment
with anti-miR-449 had a very significant impact on cell
mobility (through the Invasion assay), moreso than
cell senescence or cell death. Continued microRNA
research could reveal how to make tumours fully
immotile. The four gene targets identified are a major
area for future research; the next logical step would be
to learn more about their pathways, and how they may
directly influence breast tumour viability.
ABBREVIATIONS
BC – Breast Cancer
miR – microRNA
PCR – Polymerase Chain Reaction
ACKNOWLEDGMENTS
We would like to thank Dr. Fei-Fei Liu for allowing us
to work in her lab at Princess Margaret Hospital. Jeff
Bruce and Dr. Willa have also put in a lot of time and
effort into our experiments, and we thank them for that.
Finally, we would like to thank Ms. O’Mahony for guiding
us through this experience. Without these people, our
study would not have been possible.
REFERENCES
1. Canada, Canadian Cancer Society, Public
Health Agency of Canada. (2011, May). Canadian
Cancer Statistics 2011. Retrieved October 8,
2012, from http://www.cancer.ca/~/media/CCS/
Canada%20wide/Files%20List/English%20
files%20heading/PDF%20-%20Policy%20-%20
Canadian%20Cancer%20Statistics%20-%20
English/Canadian%20Cancer%20Statistics%20
2011%20-%20English.ashx
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2. Carlson, R. W., Allred D. C., Anderson, B.
O., Harold J. Burstein, W. Bradford Carter,
Stephen B. Edge, John K. Erban, William B.
Farrar, Lori J. Goldstein, William J. Gradishar,
Daniel F. Hayes, Clifford A. Hudis, Mohammad
Jahanzeb, Krystyna Kiel, Britt-Marie Ljung,
P. Kelly Marcom, Ingrid A. Mayer, Beryl
McCormick, Lisle M. Nabell, Lori J. Pierce,
Elizabeth C. Reed, Mary Lou Smith, George
Somlo, Richard L. Theriault, Neal S. Topham,
John H. Ward, Eric P. Winer & Antonio C.
Wolff (2009). Breast Cancer. Clinical Practice
Guidelines in Oncology, 7(2), 122-192. Retrieved
from
http://www.jnccn.org/content/7/2/122.full.
pdf+html
3. Déry, M.-A., Jodoin, J., Ursini-Siegel,
J., Aleynikova, O., Ferrario, C., Hassan,
S., & LeBlanc, A. C. (2013). Endoplasmic
reticulum stress induces PRNP prion protein
gene expression in breast cancer. Breast
Cancer Research : BCR,15(2), R22. http://doi.
org/10.1186/bcr3398
6137. Retrieved April 13, 2012, from http://www.
academicjournals.org/ajb/PDF/pdf2012/15Mar/
Mutalib%20et%20al.pdf
9. Nunez, R. (2001). DNA measurement and cell
cycle analysis by flow cytometry. Current Issues
in Molecular Biology, 3(3), 67-70.
10. Stenvang, J., Petri, A., Lindow, M., Obad, S.,
& Kauppinen, S. (2012). Inhibition of microRNA
function by antimiR oligonucleotides. Silence, 3,
1.http://doi.org/10.1186/1758-907X-3-1
11. Wang, Y., Yu, Y., Tsuyada, A., Ren, X., Wu, X.,
& Stubblefield, K. (2011). Transforming growth
factor-β regulates the sphere-initiating stem celllike feature in breast cancer through miRNA-181
and ATM. Oncogene 30, 1470-1480. Retrieved
April 14, 2012, from http://www.nature.com/onc/
journal/v3
APPENDIX
4. Grigoriadis, A., Mackay, A., Reis-Filho, J. S.,
Steele, D., Iseli, C., Stevenson, B. J., ... O’Hare,
M. J. (2006). Establishment of the epithelialspecific transcriptome of normal and malignant
human breast cells based on MPSS and array
expression data. Breast Cancer Research, 8(5),
r56. doi: 10.1186/bcr1604
5. Hashimoto, Y., Akiyama, Y., Otsubo, T.,
Shimada, S., & Yuasa, Y. (2010). Involvement of
epigenetically silenced microRNA-181c in gastric
carcinogenesis. Carcinogenesis, 31(5), 777-784.
doi: 10.1093/carcin/bgq013
6. Liu, C., & Tang, D. G. (2011). MicroRNA
Regulation of Cancer Stem Cells. Cancer
Research, 71(18), 5950-5954. doi: 10.1158/00085472.CAN-11-1035
7. Lizé, M., Klimke, A., & Dobbelstein, M. (2011).
MicroRNA-449 in cell fate determination. Cell
cycle, 10(17), 2874-2882.
Figure 1. MicroRNA expression levels in breast cancer cell
lines. Expression levels of four different miRNA (miR-449,
miR-424, miR-486, miR-181d) in four breast cancer cell
lines (MDA-MB-468, MCF-7, T47D, and MDA-MB-231B)
normalized against MCF-10A cells, obtained through a
qRT-pCR analysis. MiR-449 levels vary greatly among the
cancerous cell lines, and it was thought to potentially be a
trigger for oncogenesis.
8. Mutalib, N. A., Learn-Han, L., Sidik, S. M.,
Rahman, S. A., Singh, A. S., & Yoke-Kqueen,
C. (2012). miR-181a regulates multiple pathways
in hypopharyngeal squamous cell carcinoma.
African Journal of Biotechnology, 11(22), 612916
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DOI: 10.13034 / JSST-2016-001
Figure 2 (Left). T47D breast cancer cells transfected with
anti-miR-449 showed a decreased ability to migrate and
invade. This figure shows an image of an untreated group
of cells next to an image of treated cells after a migration
assay then after an invasion assay.
Figure 3 (Right). The treatment of MDA-MB-231B cells
with anti-miR-449 decreased the number of migrating and
invading cells. This figure shows an image of an untreated
group of cells next to an image an image of the treated
cells after a migration and invasion assay.
In Silico
predicted
53
Anitcorrelated
with miR-449a
1693
4
977
101
Figure 5. Expression levels of gene targets in cancer cell
lines. The basal expression levels of miR-449 and three
potential targets (TAF4B, XBP1, and SFXN2) in four breast
cancer cell lines (T47D, MDA-MB-231B, MDA-MB-468, and
MCF-7) and breast cell line MCF-10A, obtained through a
qRT-PCR analysis.
SFXN2
TAF4B
XBP1
13
Downregulated by
miR-449a
CRIP2
Table 1. The four genes that are predicted targets of, anticorrelated in breast cancer with, and down regulated by
miR-449a.
1693
Figure 4. In silico and experimental genomic analysis to
identify gene targets of miR-449a. Venn diagram showing
number of genes that are in silico predicted targets of miR449a (miRWalk – http://www.umm.uni-heidelberg.de/apps/
zmf/mirwalk), anti-correlated with miR-449a, and/or downregulated by miR-449a. The correlation data are from in
vitro studies collected under the Gene Expression Omnibus
database (Enerly et al., 2011) and down-regulated targets
were found in vitro through qRT-PCR analysis.
DOI: 10.13034 / JSST-2016-001
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ARTICLES
PLANARIAN REGENERATION IN RESPONSE TO DRUG
DISRUPTION OF THE WNT AND MAPK PATHWAYS
Yong Shen1, Thomas Etheridge2, Eric Hsu3, Shankar Kaushal4
Harvard University, Massachusetts Hall, Cambridge, MA 02138, USA
Rice University, 6100 Main St, Houston, TX 77005, USA
3
Washington University in St. Louis, One Brookings Drive, St. Louis, MO 63130, USA
4
University of Michigan 500 S. State Street, Ann Arbor, MI 48109 USA
1
2
ABSTRACT
The regenerative ability of planarians depends largely on its complex signaling pathways. The Wnt pathway
regulates the anterior/posterior (A/P) polarity formation after regeneration, while the MAPK pathway plays a role in
anterior regeneration. This experiment uses various drugs to disrupt the aforementioned pathways. Imatinib targets
the receptor tyrosine kinases (RTKs), a common type of surface receptors that play a role in the Wnt pathway.
PZQ is expected to affect the Wnt noncanonical calcium pathway. EHT 1864 inhibits Rac1, a GTPase involved
in the noncanonical PCP pathway. Finally, U0126 disrupts the MAPK pathway and blastemic cell differentiation.
After drug treatment, abnormal planarian regeneration is expected. The drug assays demonstrated that while both
Imatinib and PZQ have no effect on planarian regeneration, EHT 1864 under high concentration has a potent
effect on the viability of planarians during regeneration. Furthermore, U0126 caused cyclopia, a condition in which
organisms only develop one eye instead of the normal number, in planarians under high concentrations. These
observations suggest that the RTKs play a limited role in planarian regeneration, Rac1 plays a greater role than just
A/P determination during regeneration, and that U0126 affects eye and head regeneration. Our assays with PZQ
also show that different species of planarians might have different noncanonical calcium pathways.
L’abilité regénérative des planaires dépend largement sur la complexité des ses voies de signalisation. La voie
des Wnt contrôle la formation de la polarité des potentiels d’action après la regénération, alors que la voie de la
MAPK joue un rôle dans la regénération. L’imatinib cible les RTK, eux-mêmes jouant un rôle dans la voie des Wnt.
Praziquantel est attendu d’affecter la voie de calcium non canonique des Wnt. L’EHT 1864 inhibe la Rac1, un
GTPase impliqué dans la voie non canonique du PCP. Finalement, U0126 perturbe la voie de la MAPK, l’activité
de laquelle induit la différentiation des cellules souches blastémiques. Après traitement avec de la drogue, de la
regénération anormale des planaires est attendue. Les essais des drogues ont démontré que, bien que Imatinib et
PZQ n’ont pas d’effets sur la regénération des planaires, l’EHT 1864 en haute concentration a un effet potent sur
la viabilité des planaires durant la regénération. De plus, l’U0126 a causé la cyclopie chez les planaires en haute
concentration. Ces observations suggère que les RTK jouent un rôle limité dans la regénération de planaires,
la Rac1 joue un rôle plus important que simplement déterminer des potentiels d’action durant la regénération et
l’U0126 affecte les regénérations des yeux et de la tête. Nos découvertes indiquent aussi des incohérences avec
une étude par un autre groupe au sujet des effets du PZQ sur la formation polaire des planaires.
KEY WORDS
Regeneration; Planarian; Drugs; Wnt; MAPK
Regénération; Planaires; Drogues; Wnt;
INTRODUCTION
Planarians have been long known for their regenerative
abilities; even a fragment as tiny as 1/279th of the
planarian body can fully regenerate into a complete
planarian1. A large number of pluripotent, highly
undifferentiated cells called neoblasts are distributed
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throughout the planarian body; neoblasts are able to
differentiate into all planarian cell types and upon injury,
differentiate and seem to migrate in response to wound
signals1. Central to planarian regeneration are the Wnt
pathway and the MAPK pathway that determine the
DOI: 10.13034 / JSST-2016-002
polarity of planarian regeneration after receiving injury.
The Wnt pathway can be categorized further into three
pathways: the canonical pathway, the noncanonical
calcium pathway, and the noncanonical PCP pathway.
The canonical pathway is marked by the presence of the
protein β-catenin. The binding of the Wnt ligand to the
Frizzled receptor activates the Dsh protein, and through
a series of cascades promotes cytoplasmic β-catenin
accumulation. β-catenin binds to the transcription factor
TCF and acts as a cotranscription factor2. Studies on
the planarian species S. mediterranea have found that
the canonical pathway is active in the posterior end,
while it is suppressed by sFRP, a protein expressed
in the anterior end. Furthermore, RNAi of the Smedβcatenin-1 gene, which codes for β-catenin, resulted
in posterior head regeneration3. It appears that the
canonical pathway determines posterior tail formation.
The role of the noncanonical pathways in regeneration
is not thoroughly studied2. The noncanonical
calcium pathway regulates intracellular calcium ion
concentrations. It couples Dsh with a G-protein to
stimulate production of either PLC or PDE, whose
actions ultimately increase intracellular calcium ion
levels2. In the noncanonical PCP pathway, Rac1, a
GTPase, is activated. Studies have shown that Rac1 is
involved in actin polymerization, and may play a role in
cell structure and early embryogenesis2.
Our experiment involved four drugs: Imatinib, PZQ,
EHT 1864, and U0126. Imatinib, a common anticancer
drug, has been found recently to inhibit RTKs. RTKs
phosphorylate the tyrosine components of β-catenin,
which in turn stabilizes it, promotes its accumulation and
binding to TCF and consequent gene transcription4. We
hypothesized that the downregulation of the canonical
pathway due to Imatinib would cause RTK inhibition,
and consequently, posterior head formation during
regeneration.
The anthelmintic drug PZQ promotes the release of
intracellular calcium ions5. Current theory suggests that
PZQ targets membrane calcium channels, and through
some unknown mechanism, causes an influx of calcium
ions into the cell9. PZQ affects the Wnt noncanonical
calcium pathway; its actions lead to an increased
inhibition of gene transcription downstream of the
pathway9. Previous experiments have shown that PZQ
treatment caused planarian posterior head formation5.
DOI: 10.13034 / JSST-2016-002
Therefore, we hypothesized that PZQ would cause
posterior head growth.
EHT 1864 inhibits the GTPase Rac1 by inhibiting its
guanine nucleotide association6. This affects various
components downstream and causes a number of
unknown events. We hypothesized that the inhibition
of the Rac1 by EHT 1864 would disrupt the normal
functioning of planarian stem cells.
U0126 inhibits MEK1. MEK1 protein functions in
the MAPK pathway to activate ERK, which induces
blastema cell (planarian stem cell) differentiation. Thus,
MEK1 is essential for planarian development. The
inhibition of MEK1 by U0126 limits ERK activity and
thus limits blastema cell differentiation7. Since ERK is
primarily involved with blastema cells on the anterior
end7, we expected abnormal head formation on the
planarians treated with U0126.
A diverse set of pathways is involved in planarian A/P
polarity formation. The canonical pathway is mainly
involved in posterior regulation. Its activation in the
posterior end of the planarian promotes transcription of
certain genes that facilitate the posterior end to develop
into a tail. The noncanonical pathways’ functions are
unclear for the most part, but nonetheless they seem
to complement A/P polarity formation due to their
simultaneous activation with the canonical pathway.
Finally, the MAPK pathway has the important role of
regulating anterior regeneration. The main objective of
the study, as presented previously, is to disrupt these
pathways using drugs and to study whether A/P polarity
formation is affected.
MATERIALS AND METHOD
Drug Concentrations:
For the drugs PZQ, EHT 1864, and Imatinib, we
prepared five concentrations for each drug: 100 µM,
50 µM, 25 µM, 12.5 µM, and 6.25 µM in spring water
supplied by Carolina®. These dilution concentrations
were estimations based off of research papers on these
drugs and the IC50 of the drugs on non-planarian cells4,5.
For U0126, the five dilution concentrations were 10 µM,
5 µM, 2.5 µM, 1.25 µM, and 0.625 µM. U0126 dilutions
are 10 times more diluted than the other three drugs
because its IC50 is very low compared to the rest7.
Each drug was given one 6-well plate to house the five
dilutions. A control well with only spring water was set up
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Figures for: Planarian Regeneration in Response to Drug Disruption of the Wnt
and MAPK Pathways
within the Imatinib plate. We had an inadequate supply
of brown planarians after we had finished transferring
the planarians, so we instead decided to use black
planarians for the U0126 dilutions.
Planarian Drug Treatment:
The planarians used were the brown and black planarians
of the species Dugesia tigrina, from Carolina® that had
been starved for 24 hours. The planarians were cut
on iced plates by removing their heads approximately
half way between the anterior end and the anterior end
of the pharynx, and their tails at half way between the
posterior end and the posterior end of the pharynx. The
remaining fragments were washed in spring water and
two trunk fragments were pipetted into each well.
The worms were observed and photographed every
24 hours for 8 days using an optical microscope with
a camera attached and connected to a computer with
appropriate software for image acquisition.
After 48 hours of drug treatment, the worms on each
plate were transferred into a new plate with wells
containing spring water only.
RESULTS
EHT 1864 disintegrated planarians under high
concentration and stunted planarian regeneration
EHT 1864 was fatal to the planarians at concentrations
of 50µM and 100µM. After 18 hours of EHT 1864
treatment at 50 and 100 µM concentrations, the
planarians disintegrated (Figure 1A), leaving behind
body remnants (For this reason, we did not plate these
planarian in the spring water after the 48 hours). In the
EHT 25 µM, the worms never fully regenerated (Figure
1B) even after eight days, and seemed to be unable to
move. Both worms in the plate squirmed and twitched
in place, and failed to respond when prodded with
forceps. One of the worms developed a growth on the
back after 3 days (Figure 1C); the growth was round
and raised on the back. In addition to the growth, the
worm seemed to have trouble moving and flipping back
over. By the next day, however, the growth disappeared
and in its place was a small white dot. There was also
a bit of mucus on the end of the worm (Figure 1D).
The worms in the 12.5µM well (Figure 1E) exhibited a
greater degree of regeneration, with visible eyespots.
However, the regeneration appeared to be incomplete
when compared to the control (Figure 1F), with the tail
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2016 VOL 9
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A
D
C
B
E
F
G
Figure 1 1
EHT
1864
Treated
Planarians
A
he 1864
wor has
fully
Figure
EHT
1864
Treated
Planarians
A.MEHT
50µM.
disintegrated and no longer shows the sa e ody outline of typi al planarians
ale
The
worm
longer
ar indi
ates has fully disintegrated
M days and
he worno
s ha
e shownshows
little signs the
of
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ale ar indi ates
same
bodyMoutline
of
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planarians.
Scale
bar
indicates
days
he wor has a strange growth on the a of its ody
and is ha ing
le twisting
o er 25µM,
ale ar indi
D worms have
M
2.5mm.
B.trouEHT
1864
8 ates
days. The
Days he growth is no longer present nstead the wor e hi its a white spot
shown
little
signs
of
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and
are
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to
move
indi ated y arrow and has so e u us o ing off of the wor
ot hown
indi ates Scale bar indicates
M days
he wor sC.
ha eEHT
shown signs
outaleofarplace.
2.5mm.
1864
of eye de elop ent lue arrow ut ha e not de eloped a fully for ed head or tail F
25µM,
3 days.
worm
has
a strange
growth
onPronoun
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ontrol wor
daysTheear
o plete
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of head
and tail
ed
hasand
de eloped
ale ar trouble
indi ates twisting over. Scale
M
day
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its shape
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is having
bar
Fully regenerated wor after ust one day o plete with head and tail de elop ent
indicates
2.5mm.
1864 25µM, 4 Days. The growth
ail not shown
ale ar D.
indi EHT
ates
is no longer present. Instead, the worm exhibits a white
spot (indicated by arrow), and has some mucus coming
off of the worm. (Not Shown) Scale bar indicates 1 mm. E.
EHT 1864 12.5µM, 5 days. The worms have shown signs
of eye development (blue arrow), but have not developed
a fully formed head or tail. F. Control worm, 5 days. Near
complete regeneration of head and tail. Pronounced head
shape has developed. Scale bar indicates 1 mm. G. EHT
1864 6.25µM, 1 day. Fully regenerated worm after just one
day. Complete with head and tail development. (Tail not
shown) Scale bar indicates 1 mm.
regeneration stunted and the anterior head still in the
process of regeneration. In the 6.25µM, we found one
worm (Figure 1G) that had fully regenerated within a
day of being cut.
Imatinib produced no abnormal changes
All of the worms in all wells of the Imatinib plate
exhibited normal anterior and posterior regeneration.
After 72 hours, eyespots were visible in all planarians
in the Imatinib plate except for those in the 100 µM well
(Figure 2A). After 96 hours (4 days), eyespots were
clearly visible on the planarians in all wells including the
100 µM (Figure 2B). By the end of the experiment, after
192 hours (8 days), it was clear that both the head and
DOI: 10.13034 / JSST-2016-002
A
A
B
C
B
D
C
D
Figure
Treated
Planarians
A
atini
M Imatinib
days he
planarians
Figure
2 atini
Imatinib
Treated
Planarians
A.
50µM,
lear eye de elop ent three days after eing e posed to the drug eyes
3show
days.
The
planarians
show
clear
eye
development
three
indi ated y arrows
he de elop ent of the eyes oin ided with the de elop ent
of the eyes
the exposed
ontrol plate to
indithe
atingdrug
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atini does
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it the
days
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being
indicated
regeneration and de elop ent of the head at on entrations as high as
M
arrows).
The
development
of
the
eyes
coincided
with
ale indi ates
atini
M
days
en at the highest
on entration
the planarian
showing
signs within
of eye dethe
elop control
ent indi ating
ini al
the
development
ofis the
eyes
plate,
effe t of the drug on regeneration
ale indi ates
atini
M
indicating
that
Imatinib
does
not
inhibit
the
regeneration
head
days
ale indi ates
D
atini
M tail
days After days
the planarian
has a fully of
regenerated
headatand
tail showing that the
a le to
and
development
the head
concentrations
aswor
highis as
fully regenerate with no onse uen e after eing e posed to the
atini
ale
50µM.
Scale
indicates
0.75
mm.
B.
Imatinib
100µM
4
days.
indi ates
Even at the highest concentration, the planarian is showing
signs of eye development indicating minimal effect of the
drug on regeneration. Scale indicates 0.75 mm. C. Imatinib
100 µM, head, 8 days. Scale indicates 0.75 mm. D. Imatinib
100µM, tail, 8 days. After 8 days, the planarian has a fully
regenerated head and tail, showing that the worm is able to
fully regenerate with no consequence after being exposed
to the Imatinib. Scale indicates 0.75 mm.
tail of all Imatinib treated planarians had regenerated
(Figure 2C, 2D). There were no abnormal tail growth or
abnormal regeneration seen in the planarians.
PZQ produced no abnormal changes
PZQ treated planarians showed normal anterior and
posterior regeneration. After 96 hours (4 days), all
planarians in all PZQ wells except those in the 100
µM well formed visible eyes on the anterior blastema,
indicating head regeneration (Figure 3A). After 120
hours (5 days), the planarians in the 100 µM well formed
visible eyes. After 192 hours (8 days), all planarians
exhibited normal head and tail growth (Figure 3B, 3C,
3D).
DOI: 10.13034 / JSST-2016-002
Figure
A. PZQ
Day
4.
Figure P3 PZQ
TreatedTreated
Planarians Planarians
A P
M Day
lear de50µM
elop ent
of eyes
on the anterior
indi ating thatofthere
was on
ini the
al i anterior,
pa t of the drug
on regeneration
Clear
development
eyes
indicating
that
De elop ent of eyes was onsistent with the ti efra e of the ontrol wor s
D
there
minimal
regeneration.
De elop was
ent of the
head and impact
tails after of
daysthe
in P drug Mon is
the head
is the
tail and D is the entire ody here are no o ser a le defe ts or a nor alities
ale
Development
ofe eyes
with the timeframe
indi ates
for all
ept D was
n D consistent
ale indi ates
of the control worms. B, C, D. Development of the head
and tails after 8 days in PZQ 6.25µM. B is the head, C is
the tail, and D is the entire body. There are no observable
defects or abnormalities. Scale indicates 1.5 mm for all
except D. On D, Scale indicates 3 mm.
A
B
C
D
Figure 4 4 U0126
1 6 Treated
Planarians
A
M U0126
days he
wor 3had
de eloped
Figure
Treated
Planarians
A.
5µM
days.
an eye ut did not show a sign of a se ond eye a ondition nown as y lopia
The wormM had
developed an eye, but did not show a sign
days he wor had de eloped the sa e y lopia ondition as the
on entrations
he wor s ha known
e e panded
ut still see
to e part of a
of aM second
eye (a condition
aseyes
cyclopia).
B. U0126
single eye fused together D
M days A planarian had an in onspi uous
10µM
4 days. The worm had developed
the same cyclopia
eye on the left the other o erly large
ales all indi ate
condition as the 5µM concentrations. C. The worms have
expanded eyes, but still seem to be part of a single eye,
fused together. D. U0126 10 µM 6 days. A planarian had
an inconspicuous eye on the left, the other overly large.
Scales all indicate 1mm.
U0126 produced abnormal eye and head regeneration
in planarians
In the 10µM and 5µM concentrations, we noticed
abnormal eye growth on the worms. After 72 hours, we
2016 VOL 9
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21
noticed that a planarian in 5 µM well had only one eye
on its anterior blastema (Figure 4A). The next day, at 96
hours, we noticed only one visible eye forming on the
planarian in the 10 µM (Figure 4B). As for the planarians
in the 5 µM well, we observed that the previously
identified single eyes became larger and wider, almost
slit-like (Figure 4C). At 120 hours (5 days), the single
eyed planarians in 10 µM and 5 µM were still spotted
with no signs of a second visible. At 144 hours (6 days),
however, we observed a very faint and inconspicuous
second eye on all worms in the 10µM and 5µM worms
(Figure 4D). It appeared that in the 10 µM well, the two
planarians had eyes of different sizes, one of which
has a significantly larger eye on the left, the other a
significantly larger eye on the right; in the 5 µM well, the
two planarians had eyes of roughly equal size, but are
joined together so they appeared to be only one single
eye slit. All the planarians in the other concentrations
(2.5 µM, 1.25 µM, 0.625 µM) exhibited normal eye
development and regeneration. Normal eyes in those
low concentration wells were visible starting after 72
hours.
DISCUSSION
EHT 1864 disintegrated the planarians at concentrations
of 100 µM and 50 µM, consistent with the idea that the
high concentrations inhibited much of the Rac1 within
the planarians, thus disrupted actin polymerization and
cytoskeletal integrity (also a possible explanation of the
growth observed). The planarians in the 25µM well also
exhibited stunted regeneration and movement. This
may be due to EHT 1864 binding to Rac1 outside of the
Wnt pathway as well. Rac1 is a multipurpose protein
responsible for cell growth and motility within the body
in humans8. Planarian Rac1 may have similar roles.
This would explain the planarians’ failure to regenerate,
because the stem cells within the planarians would be
unable to move towards the wound and proliferate.
Imatinib did not cause abnormal regeneration. Since it
inhibits RTKs, and there are no changes in regeneration,
we suggest that RTKs play a non-essential role in the
Wnt pathway and the other pathways associated with
regeneration. The downregulation of the canonical
pathway due to Imatinib inhibition of RTKs would cause
posterior head growth, if the RTKs were integral to the
pathway. However, the possibility remains that the drug
concentrations were not sufficient to cause inhibition, or
the treatment time was not sufficient.
Carefully following the procedures of Chan and
Marchant’s (2011) study5 on PZQ’s effects on planarians,
22
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we expected both anterior and posterior head formation
during regeneration, which did not occur. The previous
study used D. japonica as their test subjects, whereas
we used D. tigrina. The paper mentioned that PZQ has
different levels of penetrance on different species of
planarians. Thus, the lack of posterior head formation
might be due to the low level of PZQ penetrance on
D. tigrina, or that the D. tigrina noncanonical calcium
pathway does not play as large a role as that of D.
japonica. We propose that the two species may have
different noncanonical calcium pathways, for the same
drug yielded different results.
U0126 treatment effected unusual eye formation. At
10µM and 5µM, a cyclops condition was first observed,
and then an abnormally large eye next to a minuscule
eye. In contrast, the eyes of planarians in the control
group developed at the same rate and have roughly
the same size each time they were photographed
(representative of the normal mode of planarian
eye development). U0126’s inhibition of the MEK1
at high concentrations resulted in low ERK levels,
downregulation of the MAPK pathway, and abnormal
cell differentiation into eye cells. This is supported by the
observation that at concentrations of 0.625, 1.25, and
2.5 μM, the planarians regenerated normal eyes earlier
than those in 5 and 10 μM. The general trend is that the
higher the U0126 concentration, the more abnormal the
eye development. Since the MAPK pathway seems to
be directly involved in eye development, we speculate
that it may regulate a gene that participates in eye
development.
Though the experiment was successful, we did make
some errors. For instance, in the 6.25µM EHT 1864
plate, we found a worm (Figure 5G) that had fully
regenerated within a day. We decided to replate a new
6.25µM EHT 1864 well the next day. The other worms
in the original 6.25µM and the new 6.25µM wells did
not show complete regeneration, confirming that there
was a human error in worm cutting. Furthermore, our
experimental procedure had some limitations, primarily
because we had to cut the planarians under microscopes
and approximate the cutting locations; different cutting
locations might result in different rates of regeneration.
FUTURE DIRECTIONS
Due to time constraints, we were unable to repeat our
drug assays. To further confirm the validity of our results,
more tests need to be conducted.
Furthermore, more research need to be conducted on the
drugs. The major limitation of the research is that it relies
heavily on pure observational analysis and is lacking in
DOI: 10.13034 / JSST-2016-002
quantitative measurements. Future experiments can
complement observations with procedures such as
protein expression staining to quantify the extent of
protein expression during development. In addition, in
order to determine whether the disruption of the Wnt
pathway is solely responsible for the results from EHT
1864, a second experiment using a drug, or RNAi,
that is specific for the noncanonical PCP pathway
needs to be performed. More research is needed to
determine the cause behind the different responses
of D. tigrina and D. japonica to PZQ. Furthermore,
the concentration of Imatinib should be increased
to clarify whether RTKs serve an important role in
planarian regeneration, to eliminate the possibility of
having inadequate concentration. Finally, in order to
elucidate the functions of the MAPK pathway in regards
to eye development, RNAi should be used on further
downstream components.
ABBREVIATIONS
Abbreviation
A/P
MAPK
RTK
PZQ
Dsh
TCF
sFRP
PCP
RNAi
ERK (a.k.a. MAPK)
MEK1 (a.k.a MAP2K1)
Full Form
Anterior/Posterior
Mitogen-activated protein
kinases
Receptor Tyrosine Kinase
Praziquantel
Dishevelled
Transcription Factor
Secreted Frizzle Related
Protein
Planar cell polarity
RNA interference
Extracellular-signal-regulated
kinases
Dual specificity
mitogen-activated protein
kinase kinase 1
ACKNOWLEDGEMENTS
We would like to thank University of Chicago’s
Biological Sciences Division, our research mentors Dr.
Schonbaum, Dr. Zaragoza, and our TA Westin Tom for
their adamant support for the planarian experiment.
This research project was a collaborative effort between
all members of the team. All members contributed to all
aspects of the research project.
DOI: 10.13034 / JSST-2016-002
REFERENCES
1. Reddien, P. W.; Alvarado, A. S. Fundamentals of
Planarian Regeneration. Annual Review of Cell
and Developmental Biology 2004, 20, 725–757.
doi:10.1146/annurev.cellbio.20.010403.095114
2. Komiya, Y.; Habas, R. Wnt signal transduction
pathways. Organogenesis 2008, 4, 68–75.
doi:10.4161/org.4.2.5851
3. Petersen, C. P.; Reddien, P. W. Smed-βcatenin-1
Is Required for Anteroposterior Blastema Polarity
in Planarian Regeneration. Science 2008, 319,
327–330. doi:10.1126/science.1149943
4. Zhou, L.; An, N.; Haydon, R. C.; Zhou, Q.;
Cheng, H.; Peng, Y.; Jiang, W.; Luu, H. H.;
Vanichakarn, P.; Szatkowski, J. P.; Park, J. Y.;
Breyer, B.; He, T.-C. Tyrosine kinase inhibitor
STI-571/Gleevec down-regulates the β-catenin
signaling activity. Cancer Letters 2003, 193, 161–
170. doi:10.1016/S0304-3835(03)00013-2
5. Nogi, T.; Zhang, D.; Chan, J. D.; Marchant,
J. S. A Novel Biological Activity of Praziquantel
Requiring Voltage-Operated Ca2+ Channel β
Subunits: Subversion of Flatworm Regenerative
Polarity. PLoS Negl Trop Dis 2009, 3, e464.
doi:10.1371/journal.pntd.0000464
6. Shutes, A.; Onesto, C.; Picard, V.; Leblond,
B.; Schweighoffer, F.; Der, C. J. Specificity and
Mechanism of Action of EHT 1864, a Novel Small
Molecule Inhibitor of Rac Family Small GTPases.
J. Biol. Chem. 2007, 282, 35666–35678.
doi:10.1074/jbc.M703571200
7. Tasaki, J.; Shibata, N.; Nishimura, O.; Itomi,
K.; Tabata, Y.; Son, F.; Suzuki, N.; Araki, R.;
Abe, M.; Agata, K.; Umesono, Y. ERK signaling
controls blastema cell differentiation during
planarian regeneration. Development 2011, 138,
2417–2427.
8. Ridley, A. J. Rho GTPases and actin dynamics
in membrane protrusions and vesicle trafficking.
Trends Cell Biol. 2006, 16, 522–529. doi:http://
dx.doi.org/10.1016/j.tcb.2006.08.006
9. Greenberg, R. M. Are Ca2+ channels targets
of praziquantel action?. International Journal
for Parasitology 2005, 35, 1–9. doi:10.1016/j.
ijpara.2004.09.004
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ARTICLES
EFFECTIVENESS AND TOXICITY OF OIL SPILL REAGENTS ON
ARTEMIA SALINA
Neel A. Sharma
Kingston Collegiate & Vocational Institute, 235 Frontenac St, Kingston, Ontario, K7L 3S7 Canada
ABSTRACT
To determine the safety and effectiveness of three potential agents which could be used to manage an oil spill. Methods:
The effectiveness of three agents to manage an oil spill was evaluated: liquid soap, human hair, and Enviro-Bond 403
polymer. These agents were selected as soap can emulsify oil, and hair and polymer act as adsorbants. To evaluate
safety, 1 hour- Artemia Salina (brine shrimp) survival was evaluated, as Artemia is a commonly used organism for
toxicity studies. Serial dilutions were employed to construct lethal concentration curves to estimate the concentration
at which 50% of the organisms would die (LC50) for a normal environment (control), for an oil spill (control 2) and for an
oil spill managed with each of the 3 agents. Results: Hair and polymer were effective adsorbents as 12% and 20% of
the oil remained unbound at 1 hour; soap was ineffective with 62% of oil remaining unbound. An hour after exposure
to water with chemicals leeched from an oil spill, there was a 63% reduction in survival in Artemia, when compared
to natural conditions (p=0.001). Oil exposure exhibited a classic dose response curve as more Artemia died with
increasing concentrations of oil; the associated LC50 was 17.5%. Hair and polymer were well tolerated by Artemia –
neither reached their LC50 and approximately 80% of Artemia were alive at the end of one hour. Soap, with or without
oil, was toxic to Artemia and its LC50 was 7%. These differences in survival were statistically significant between the
three groups (ANOVA; p-value = <0.001). Hair and polymer we both effective and well tolerated by Artemia in an oil
spill; soap was not effective and was toxic to Artemia.
Objet: Pour déterminer la sécurité et l’efficacité de trois réactifs qui pourraient se servir à nettoyer une marée
noire artificielle. Méthodes: L’efficacité de trois agents en nettoyant une marée noire artificielle a été évaluée:
celle du savon liquide, de cheveux humains, et du polymère Enviro-Bond 403. Pour voir si ces agents sont sûrs,
la survie de l’Artemia a été observée pendant une heure, et les dilutions en série ont été faites pour construire
des courbes CL50 représentant un environnement normal (1er groupe témoin), une marée noire (2e groupe
témoin), et une marée noire nettoyée avec chacun des trois agents. Résultats: Les cheveux et le polymère ont
été des bons absorbants car seulement 12% et 20% du pétrole y restait après une heure, respectivement. Par
contre, le savon a été inefficace car encore 62% du pétrole y restait. Pendant la première heure, la survie de
l’Artemia dans une marée noire non traitée a été réduite par 63%, comparé aux conditions naturelles (p=0.001).
L’exposition au pétrole a produit une courbe dose-réponse conventionnelle car plus d’Artemia sont morts quand
la concentration du pétrole a été augmentée; son CL50 a été 17.5%. L’Artemia a supporté les cheveux et le
polymère puisqu’aucun agent a atteint son CL50, et environ 80% de l’Artemia ont survécu après une heure. Le
savon, n’importe s’il y avait du pétrole, a été toxique à l’Artemia et son CL50 a été 7%. Ces résultats ont été
importants statistiquement parmi ces trois groupes (ANOVA; valeur p =<0.001). Conclusion: Les cheveux et le
polymère ont été tous les deux des agents efficaces que l’Artemia a supporté dans un environnement de marée
noire artificielle.
KEY WORDS
Cleaning an oil spill; Artemia; toxicology; absorbents; lethal concentration 50; LC50 Nettoyer la marée noire;
Artemia; la toxicologie; les absorbants; la concentration létale médiane 50; CL50
INTRODUCTION
The British Petroleum Oil Spill in the Gulf of Mexico
in 2010, also known as the Deepwater Horizon Oil
Spill, resulted in one of the greatest man-made
disasters that the world has seen, affecting marine,
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bird and insect life.1-4 The disaster may affect the
area for decades to come and has raised many
important questions about how an oil spill should be
effectively and safely managed.5-7An oil spill can be
DOI: 10.13034 / JSST-2016-003
managed by a variety of methods including burning
the spilled oil, by skimming or mechanically removing
it, using chemicals to disperse or break it up, and
using chemicals to absorb it.5,6 While many agents
have been used in oil spills, no one is sure which
is the most effective and how well these agents are
tolerated by marine life.7
The purpose of this study was twofold: to evaluate
the efficacy and safety of different methods used to
clean up an oil spill. The three agents chosen were
soap, hair and a polymer. These were chosen as
polymer is the traditional compound that has been
used but it is expensive and little is known about its
safety on aquatic life.4,5 Hair, a solution that could use
recycled material, has been suggested. Lastly, soap
has also been suggested to clean up a spill due to its
emulsifying properties.5
To evaluate safety, a series of oil spills was simulated,
and the effect of the oil and different cleaning agents
was evaluated on a culture of Artemia Salina (brine
shrimp), an organism frequently used for toxicology.8-10
A 10L salt-water mixture was created by adding sea
salt (H2O Ocean Pro+) to distilled water to create a
30 ppt concentration (specific gravity of 1.024) for the
purpose of dilution. A culture tank of Artemia Salina
was also created.
The following three agents were evaluated to
determine which was the most effective agent at
cleaning up an oil spill: a polymer (Enviro-bond 403
polymer11), human hair and Sunlight dish soap.
from the oil into the water, similar to a method outlined
by Schein et al.14 This was replicated three times.
Following this, a 0.037 g/ml concentration of each
agent to solution was created but allowing a 1-hour
contact time of the agent to solution. Controls consisted
of salt water only or oil and saline. Each agent was
also tested without oil. After 1-hour of contact time
the oil/agent mixture, or agent alone, was removed by
a spoon. Following this step, the remaining solution
was used to create a series of dilutions to evaluate
toxicity on Artermia: 50%, 25% and 12.5%.
Ten Artemia organisms were added to 20 ml of each
concentration of fluid in petri dishes. After 1 hour,
the number of living organisms was quantified by
noting the number of surviving organisms by light
microscopy. This toxicity experiment was performed
3 times for each agent and control to obtain precise
estimates of survival, and included the analysis of 96
samples.
To quantify toxicities the LC50 was calculated for
each agent by creating a series of survival curves
and extrapolating the concentration at which 50%
of organisms were alive.15 An analysis of variance
(ANOVA) was calculated to determine if there were
statistically significant differences in the average
1-hour survival between the 3 groups using an
agent.16 A t-test was also used to compare survival
in oil and saline only.17 Statistical significance was
To quantify the effectiveness of each of the three
compounds, a concentration of 0.037 g/ml was
created by adding 2.6 grams of the compound to 20
ml of Mobil 1 motor oil and 50 ml of saline water (30
ppt or 1.024 density). While not a perfect correlate to
crude oil, given the addition of wax to alter its viscosity
at different temperatures, oil has been recommended
by NASA as a substitute for crude in simulated oil
spill experiments.12 At the end of the hour, the agent/
oil matrix was removed by skimming it from the top
of the solution. The remaining, non-adherent oil was
measured using a 10 ml syringe.
A 5:2 ratio of salt water to oil solution was created in a
beaker.13 This mixture was stirred for 10 minutes and
left still for 24 hours, to allow for leaching of chemicals
DOI: 10.13034 / JSST-2016-003
Figure 1: Artemia Survival in Oil and Water (control)
Artemia survive in salt water (77% survival) but not in oil
(LC50 = 17.5%)
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1-hour estimate of Artemia survival in natural history.
In comparison, only 30% of Artemia survived when
exposed to the combination of oil and water. These
differences in 1-hour survival were statistically
significant (p-value=0.001).
A dose response curve was noted as when the
oil concentration increased, a greater number of
Artemia died; the LC50 was 17.5% (t-test = 22; p-value
= 0.0001).
Figure 2: Artemia Survival with Agent Alone (Water
but no Oil)
Hair and polymer well tolerated (green and purple) but
soap kills Artemia. LC50 for soap less than 10%. ANOVA;
p-value <0.001 )
assumed if the p-value was less than 0.05.18
Hair and polymer were well tolerated by the Artemia,
and LC50 values were not reached (Figures 2 and
3). Of the 24 samples exposed to hair, the mean
Artemia 1-hour survival was 82% (SD = 14.3%). For
polymer, the survival, was 77% (SD = 15.6%). Soap
was associated with an LC50 of 7% with oil and 10%
without it. The differences in 1-hour survival were
statistically significant between the 3 groups (ANOVA;
p-value <0.001).
DISCUSSION
Oil spills can create long-lasting toxic effects on
the environment.19,20 It is important to find solutions
that can clean up an oil spill that can be practically
used and that are effective. Furthermore, solutions,
themselves need to be safe, otherwise, toxicity to
marine life can be compounded.
Hair and polymer are both effective in absorbing
the spilled oil, as they absorbed 88% and 80%
of the material, respectively. Soap, however, is
not comparable at absorbing an oil spill, as it only
absorbed 38% of the spilled oil. Based on their
effectiveness, both polymers and natural products
that can absorb oil should be used for oil spills.
Figure 3: Artemia Survival with Oil Spill and Agent
Hair and polymer are both well tolerated in oil spill but
Artemia cannot survive soap exposure. LC50 for soap is
7%.
RESULTS
Both hair and polymer were effective absorbents of
oil, absorbing 88% and 80% of the oil. Thirty-eight
percent of the oil was absorbed with soap.
On average, 77% of Artemia exposed to salt water
were alive after one hour (Figure 1), providing a
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The toxicity study showed that soap was toxic to
Artemia, given its LC50 was 7% and 10% with and
without oil. Hair and polymer were well tolerated by
these organisms; in fact to the point that an LC50 was
not able to be quantified (70-80% percent survival).
The observed differences in toxicity were statistically
significant (p<0.05). This finding is important because
an ideal agent should not only be effective but must
be safe for marine life.21,22
Some sources of error were various health levels and
ages of Artemia; if the samples randomized to soap
contained elderly shrimp or ones that were potentially
ill, a bias may have been introduced, influencing
DOI: 10.13034 / JSST-2016-003
the survival of the Artemia in those randomized to
soap. The process of randomization would reduce
this possibility. Another potential bias was the nonstandard method of skimming. While an attempt was
made at removing the same amount of agent and
oil, this was done by hand and may not have been
replicated exactly from trial to trial. Finally, there was
no time dimension for survival, so there was no way
of knowing how fast each brine shrimp died. For
instance, if 20% of a sample group were to die in the
first 5 minutes after exposure to polymer as opposed
to as 55 minutes after exposure to hair, the improved
survival would not be noted using survival at 1-hour,
as both would have 80% 1-hour survival. Using
survival analysis is a method that adds the dimension
of time to survival, and should be considered in future
studies evaluating toxicity of agents on Artemia. It
should also be noted that Artemia survival was used
as a marker for marine or environmental impact.
This choice, while practical, may not encompass the
totality of an agent’s impact on a marine ecosystem.
For instance, a compound may be well tolerated
by Artemia, but not by other forms of marine life,
either located higher or lower on the food chain than
Artemia. Additionally, an agent may also have an
affect on non-living elements of ecosystem, which,
too, may ultimately impact marine life.
Many people have had various ideas about the best
way to clean up an oil spill including the use of natural
compounds such as hair, cotton and wood.22 While
polymers are commercially available, natural products
have the benefit of being potentially cost-effective.21
The results of this study show that hair and polymer
are very effective at cleaning up the simulated oil spill.
Both are equally safe on aquatic life, given the high
tolerance of these two compounds by Artemia. Since
hair has the additional benefit of being less costly,
it might be a much more cost effective solution and
might be a technology that is used in the future.
important to humanity because as oil reserves on
land become diminishes, we will become increasingly
reliant on marine reservoirs of oil. Therefore, in the
future, we should expect a higher rate of oil spills in
our oceans and a greater impact on marine life, which
can forever change marine ecosystems.23
ABBREVIATONS
Abbreviations
SOS
LC50
BP
ANOVA
Full Form
Simulated oil spill
Lethal concentration fifty
British Petroleum
Analysis of variance
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1. Teal J. M. & Howarth R. W. Oil spill studies: a
review of ecological effects. Environ. Manage.
1984, 8, 27–44.
2. Whitehead A, Dubansky B, Bodinier, C, Garcia,
TI, Miles, S, Pilley, C, Galvez, F. Genomic and
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the National Academy of Sciences of the United
States of America, 212, 109(50), 20298–20302.
http://doi.org/10.1073/pnas.1109545108.
3. Belanger M., Tan L., Askin N. & Wittnich C.
Chronological effects of the Deepwater Horizon
Gulf of Mexico oil spill on regional seabird
casualties. J. Mar. Animal Ecol. 3(2), 10–14
(2010).
4. Husseneder, C., Donaldson, J. R., & Foil, L. D.
(2016). Impact of the 2010 Deepwater Horizon
oil spill on population size and genetic structure
of horse flies in Louisiana marshes. Scientific
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srep18968
FUTURE DIRECTIONS
5. Merv Fingas. The Basics of Oil Spill Cleanup,
Third Edition. CRC Press LLC. Boca Raton, FL.
2012, p286.
While human hair is an effective method to clean up
spilled oil, further research needs to be performed to
ensure that it can be a realistic option that can be
used in the field. Other areas of future interest include
developing a system of obtaining and deploying
human hair to an oil spill or creating a synthetic form
of hair that replicates its essential absorbent qualities
and is well tolerated by marine life. This issue is very
6. Song D, Liang S, Zhang Q, Wang J, Yan
L. Development of High Efficient and Low
Toxic Oil Spill Dispersants based on Sorbitol
Derivants Nonionic Surfactants and Glycolipid
Biosurfactants.
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Environmental
Protection. 2013, 4, 16-22.
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7. Verriopoulos G, Moraitou-Apostolopoulou M,
Milliou E. Combined toxicity of four toxicants
(Cu, Cr, oil, oil dispersant) to Artemia salina. Bull
Environ Contam Toxicol. 1987, 38(3), 483-90.
8. Sorgeloos P, Remiche-Van Der Wielen,
Persoone G. The Use of Artemia nauplii for
toxicity tests – a critical analysis. Ecotoxicology
and Environmental Safety. 1978, 2, 249-255.
9. Persoone G, Wells PG. Artemia in aquatic
toxicology: a review. In Artemia Research and its
Applications. 1987, Vol 1. Morphology, Genetics,
Strain Characterization Toxicology. Sorgeloos
P, Bengtson DA, Decleir W, Jaspers E (Eds).
Universa Press, Wetteren, Belgium; 380 p.
10. Anita George-Ares, Eric J. Febbo, Daniel J.
Letinski, Joseph Yarusinsky, Regina S. Safadi,
and Alice F. Aita Use of Brine Shrimp (Artemia)
In Dispersant Toxicity Tests: Some Caveats.
International Oil Spill Conference Proceedings:
April 2003, Vol. 2003, No. 1, pp. 327-330.
11. Envirobond 403 polymer. http://www.envirobond.com/ebond.html
18. Goodman SN. Toward evidence-based medical
statistics: the p-value fallacy. Ann of Inter Med.
1999; 131:995-1004.
19. Schein A, Scott JA, Moz L, Hodson
PV. Oil dispersion increases the apparent
bioavailability and toxicity of diesel to rainbow
trout (Oncorhynchus Mykiss). Environmental
Toxicology and Chemistry, 2009, 28(3), 595-602.
20. McIntosh S, King T, Wu D, Hodson PV. Toxicity
of dispersed weathered crude oil to early life
stages of Atlantic herring (Clupea Harengus).
Environmental Toxicology and Chemistry, 2010,
29(5), 1160-1167.
21. Bayat, Ahmad, et al. Oil spill cleanup from sea
water by sorbent materials. Chemical engineering
& technology 2005, 28(12), 1525-1528.
22. Choi H, Cloud RM. Natural sorbents in oil spill
cleanup. Environ Sci Technol. 1992, 26, 772-776.
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SB100014240527023034420045791235602250
82786. (accessed March 4 2016).
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activities/ts2hiac1.pdf
13. Hodson P. Do chemical dispersants make spilled
oil more toxic to fish. SETAC 2010 (Presentation).
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PV. Oil dispersant increases the apparent
bioavailability and toxicity of diesel to rainbow
trout (oncorhynchus mykiss). Environmental
Toxicology and Chemistry. 28 (3):595-602.
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LB, Nichols DE, McLaughlin JL. Brine shrimp:
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Statistics. 2005, 33, 1–53.
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Educational Statistics, 15(1), 84–87. http://doi.
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ARTICLES
SINGLE NOTE DISSONANCE THROUGH HARMONIC
SELF-INTERFERENCE
Maxwell Ng
McMaster University 1280 Main Street West Hamilton, Ontario L8S 4L8, Canada
ABSTRACT
Musical dissonance is generally understood in terms of two simultaneous notes. However, low frequency notes
sound dissonant when played alone on a piano. The explanation proposed in this work is that this dissonance
arises from the harmonics of the played note interfering with one another.
Using the piano as a model, perceived dissonance was calculated through the combination of the two-tone
dissonance formula with the A-weighting curve and the different harmonic intensities of a piano. Sound spectrums
of sample piano notes were used to compare harmonics of low frequency and high frequency notes.
Single note dissonance increased rapidly as note frequency decreased. A-weighting had no qualitative effect on
the dissonance-frequency trend, implying a physical and not an aural cause. As verified in the sound spectrums,
the lower register note had harmonics closer together, compared to the higher register note. It is thus possible
that the harmonics of low notes interfere significantly with each other, thereby producing the observed single-note
dissonance.
The simulation produces a score for the perceived dissonance of a single-note played on the piano. This analysis
could be adapted in the future to other instruments, including aerophones, as well as integrate timbre, partials, and
inharmonics.
La dissonance musicale et pour la plupart compris en matière de deux notes simultanées. Cependant, les notes
de basse fréquence semble en désordre quand ils sont joués seules sur un piano. L’explication proposée dans
cet œuvre est que cette dissonance se produit des harmoniques des notes qui s’interfèrent.
Utilisant le piano comme exemple, la dissonance perçue a été calculé par la combination de la formule de
dissonance entre deux notes avec la courbe de pondération A et les intensités harmoniques d’un piano. Les
spectres sonores des notes de piano ont été utilisés pour la comparaison des notes de basse et haut fréquences.
La dissonance des seules notes augmentait rapidement alors que les fréquences des notes diminuaient. La
pondération A n’avait pas eu un effet sur la tendance entre la dissonance et les fréquences, qui signifie la
présence d’une cause physique au lieu d’une cause auditive. Vérifié dans les spectres sonores, la note de
registre inférieur avait ses harmoniques plus proches comparés à la note du registre plus haut. C’est alors
possible que les harmoniques des notes des registres inférieurs interfèrent considérablement avec les unes les
autres, et produit ainsi la dissonance des seules notes observée dans les calculs.
La simulation produit un résultat pour la dissonance perçue sur un piano. Cette analyse pourrait être adaptée
dans le futur aux autres instruments, incluant les aérophones, et puis intégrer aussi des analyses de timbre, des
tons simples, et des inharmoniques.
KEY WORDS
Dissonance; Music; Harmonic; Note; Interference
INTRODUCTION
Music can be defined as the use of sounds, from any
number of instruments, to express and evoke feelings
and emotions. What makes good music and what
makes bad music has been, and will likely remain,
DOI: 10.13034 / JSST-2016-004
a point of debate and discussion. One intriguing
facet of music near the center of that conversation
is music’s ability to create consonance, as well as its
more infamous foil, dissonance. Consonance can be
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considered a harmonious or pleasant sound from the
combination of musical notes, while dissonance is the
unpleasant quality of sound.
Helmotz theorized that dissonance was produced
from the interference between two tones to produce
displeasing beatings.1 For strings, this beat theory is
applicable by considering interfering standing sine
waves on the strings as analogous to their interfering
emitted sounds. However, in the field of dissonance,
while much has been studied for two notes, more
research is possible in terms of the dissonance
produced by a single note. Each instruments has a
unique timbre, or sound quality. On a piano, as the
played note is lowered in pitch, there is a noticeable
increase in the roughness, unclarity, or murkiness of
the sound quality. This texture is a dissonance caused
uniquely from playing a single note.2 Because this effect
is common to many instruments, its explanation must
also be adaptable or analogous across instruments.
With inspiration from beat theory, there may be a
physical interference in emitted sound waves that is
causing this single-note dissonance. The difference
from the usual approach is that there are not two notes
being played, but rather a single note. An important
consideration is to regard the single note not as a single
frequency. On traditional instruments, any note played
will generate harmonics – frequencies higher than the
intended fundamental frequency.2 It is possible that
the notes in the middle and upper registers may be
perceived more clearly as pure or single tones, having
less audible harmonics. However, the harmonics
created from a single note in the lower register may
be much more audible to the human ear. These lowregister harmonic frequencies, if perceived by the ear,
may be close enough to the fundamental frequency
and each other to create beats and thus dissonance.
This interference may have implications in the
development of new instruments, as well as the tuning
of existing instruments. While instruments may create
a theoretical fundamental frequency, the sound heard
by the human ear may be quite different due to this
single-note dissonance effect. Lower-register note
self-dissonance is also important to music theory, as
well as reconsidering any unnatural use of low pure
tones instead of bass notes during acoustic tests.
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The mechanism proposed in this work postulates that
notes played in the lower registers of instruments can
create dissonance when played on their own due to
interference from and amongst their own harmonics. A
mathematical model of the piano, including harmonics
and two-tone dissonance production, is used to analyze
whether self-dissonance is significantly greater in
lower-register notes than higher-register notes.
Instrument Model
The standard 88-note piano is used as a stringed
instrument model, played at approximately 60dB.3
Note frequency increases from left to right on the
piano keyboard. The piano utilizes strings bound on
both ends. Hence, the corresponding physics can be
simulated as a standing wave on the string.
Keyboard to frequency formula, 12-TET
To convert between a note on the piano keyboard
with a frequency, the piano was assumed to be tuned
using the Twelve-Tone-Equal-Temperament (12-TET)
scale. This allows any note n to be converted into its
respective frequency via the formula
is the frequency of the nth note, n is the numerical
coordinate of the piano keyboard note, and 440 Hz is
the frequency of the 49th note (A4 ), held as a standard.
Trigonometric assumption of sound waves
Pure tone sounds are assumed to be held at a constant
frequency with constant amplitude. Their periodic
nature can be described by a sine wave, with nodes at
both ends of the string.
Two-tone dissonance formula
The relative dissonance created from two
frequencies is approximated by Jensen in the formula
where g is the value of the higher frequency note, f is
the value of the lower frequency note, and Ig and If are
their respective intensities.5,6
DOI: 10.13034 / JSST-2016-004
Harmonic intensities of a piano
The intensities of the harmonics from piano strings
vary according to the following values, measured by
Helmoltz7:
I1 = 1.0, I2 = 2.9, I3 = 3.6, I4 = 2.6, I5 = 1.1, I6 = 0.2, and
I7+ = 0.0.
A-weighting curve from equal-loudness contours
human perception. The physical restrictions are that
(i) there is no dissonance for union (f = g), and (ii) an
intensity of 0.0 leads to no dissonance.
The resulting perceived dissonance formula:
3. Mathematical simulation of a single note’s harmonics
self-interference dissonance
To compensate for the human ear’s non-uniform
perception of the loudness of sounds at different
frequencies, the A-weighting curve was used, given by
the International Standards Organization as:
Using the new perceived dissonance formula, this
formula can be appropriated to a single note under
certain conditions if g is taken as the harmonic
of f. When using A-weighting, the following data is
calculated (Figure 2). Without using A-weighting, the
following data is calculated (Figure 3).
Where A(f) is the decibel difference to what the human
ear perceives the frequency f to be, as compared to a
standard 1000 Hz sound. 8
4. Sound spectrums of sample notes on a piano
Computer software
Microsoft® Excel® for Mac 2011 was used for
calculations and data plots. MacCRO X was used to
obtain sound spectrums from a Yamaha digital piano.
Grapher was used for graph generation.
RESULTS
1. Maximum dissonance for two pure tones
The dissonance formula
can be rewritten
asby performing a substitution where
As representative of a low register note, a sound
spectrum of the A2 note is sampled (Figure 4). As
representative of a high register note, a sound
spectrum of the A5 note is sampled (Figure 5).
DISCUSSION
This mathematical analysis of the harmonics produced
by a piano model is intended to investigate the
possible dissonance produced by a single note’s own
harmonics. The hypothesis is that this harmonic selfinterference is the primary factor that leads to the
observed dissonant texture of lower register notes,
as opposed to the clarity and purity of higher register
notes.
2. Derivation of two-tone perceived dissonance formula
There is a relatively strong increase in the perceived
dissonance of a single note as its fundamental frequency
is decreased towards low-register notes (Figures 2,
3). The qualitative rise in dissonance is similar in both
the simulation with A-weighting, as well as without the
A-weighting. Therefore, the single-note dissonance
is most prevalently a physical phenomenon, and less
so due to human aural conditions for perception. As
expected, there is relatively very low dissonance in the
middle (C4) and upper (C5 and onward) registers.
The intensity of a piano being played has been
measured at roughly 60dB.7 Assuming 60dB is
registered for the fundamental frequency, the
intensities of the harmonics can be calculated through
corresponding multiples of the sum of 60dB and the
Helmholtz’s harmonic intensities. The A-weighting
calculation is added to this intensity to compensate for
The spectrum of the lower register note A2 (Figure 4)
has harmonics that are much closer to one another in
terms of absolute frequency, in comparison with the
spectrum of the upper register note A5 (Figure 5). This
validates the trigonometric assumption of the bound
wave, such that the harmonics of A2 are closer due
to them being multiples of a smaller fundamental
.6
The solution for the value of frequency g (gmax) that
provides maximum dissonance given frequency f, via
calculus (a full derivation is presented in the Appendix),
is gmax=1.01931f +17.4672 in Hertz
The two tone dissonance function can be graphed
and the maximum dissonance value can be identified
(Figure 1).
DOI: 10.13034 / JSST-2016-004
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frequency value, in comparison to the higher note A5.
The use of varying intensities of harmonics increases
the accuracy of the simulation. The spectrum’s shape
in harmonic intensities supports the used harmonic
intensity data for the dissonance simulation.
A possible reason for this single-note dissonance
phenomenon is due to the closeness of these harmonics.
As seen in the spectrums, as the frequency of the note
decreases, the closer the harmonics become to one
another. This proximity can lead to interference amongst
the harmonics themselves, leading to the beats and
therefore the observed dissonance. However, in higher
register notes these harmonics would be too far apart
to have significant interference with one another within
the human ear, as calculated in Figure 2 and 3, and
observed in Figure 4, compared to Figure 5.
The A-weighting scale is used to calibrate for varying
the auditory intensities of the human ear . Without the
use of A-weighting the dissonance of lower register
notes is increased, likely because the loudness of the
sound in total has been increased.
The piano is the simplest model for analysis, due to
its bound strings and straightforward construction
concept, with a wide frequency range divided visually
through its keyboard. While the fundamental loudness
may not be exactly 60dB for each note of the piano at
all times, the calculations are relative, so this variation
can be dismissed for the purposes of this investigation.
A key assumption in this simulation is that all nonfundamental frequencies generated are harmonics;
however, this may not be true. Inharmonics occur when
overtones are not integer multiples of the fundamental
frequency. However, inharmonics are not significant for
lower register notes, thereby preserving the validity of
the simulation.9
Due to the qualitative nature of the sensation of
dissonance, it is hard to quantify. However, the twotone dissonance formula can be validated by solving
for gmax, and comparing it to the experimental result.
For the standard f = n49 = A4 = 440 Hz, the formula
predicts gmax = 465.96 Hz. This frequency is very close
to that of the Minor Second interval of n49, given as n50 =
A#4 = 466.16Hz ≈ 465.96Hz = gmax. The Minor Second
interval is considered the most dissonant interval,
and has been accurately predicted. Furthermore,
the original two-tone dissonance formula by Jensen
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is based on the work by Sethares and Benson.6 The
peak dissonance occurs when two frequencies occur
at approximately 1/4 of the critical bandwidth.6 The
dissonance formula reflects this peak in dissonance
due to the nature of the critical bandwidth, as well as
takes into account that the critical bandwidth increases
with the registered fundamental frequency. While the
specific mechanics of the critical bandwidth is outside
the aim and scope of this investigation, the beat theory
of Helmholtz is seemingly verified as these beats can
be produced within the critical bandwidth and can
therefore produce the perceived dissonance.
CONCLUSION
In agreement with observations, the dissonance
produced by a single note increased as its fundamental
frequency decreased. By the 4th octave and into
subsequent higher octaves, dissonance values were
similarly low in comparison with octaves below the 4th.
A-weighting had no effect on this qualitative trend.
This investigation was limited to assuming only
harmonics are generated in the piano model. A more
complete simulation would include partials dependent
on the instrument. While the inharmonic effects are
not significant in the bass, higher octaves have strong
deviation in harmonic frequencies, and may create their
own form of single-note dissonance.9 This analysis can
also be adapted to other instruments, including other
chordophones or aerophones, to examine the effect of
instrument construction. These models are important
to form a more complete theory of acoustic dissonance
on the mind. The study of dissonance could provide
answers and analyses to several questions: how do
musical conventions and interpretations of dissonance
differ between cultures and genres, and how might this
affect the use or scarcity of low-register notes in music.
ABBREVIATIONS
Hz
n
Hertz
note
ACKNOWLEDGEMENTS
I would like to thank Mr. Price, Mr. Seltzer, Dr. Tannous,
Mr. Gaalaas, and Mr. Arnot-Johnston of TFS –
Canada’s International School and the International
Baccalaureate for providing support and the opportunity
to pursue this investigation.
DOI: 10.13034 / JSST-2016-004
REFERENCES
For maximum dissonance:
1. Benson, D. Music; Cambridge University Press:
Cambridge, 2007; pp. 139-142.
The two tone dissonance function can be graphed
and the maximum dissonance value can be identified
(Figure 1).
2. Levitin, D. This is your brain on music; Dutton:
New York, N.Y., 2006.
3. Chasin, M. Hear The Music: Hearing Loss
Prevention for Musicians; 4th ed.; Dr. Marshall
Chasin: Toronto, 2001; p. 5.
4. Music Acoustics,. Note names, MIDI numbers
and frequencies https://newt.phys.unsw.edu.au/
jw/notes.html (accessed Jan 4, 2013).
5. Plomp, R. The Journal of the Acoustical Society
of America 1965, 38, 548. [Online]
6. Deriving the Musical Scale. The Dissonance
Curve
and
Applet
http://jjensen.org/
DissonanceCurve.html (accessed Jan 7, 2013).
7. Helmholtz, H.; Ellis, A. On the sensations of tone
as a physiological basis for the theory of music;
Dover Publications: New York, 1954.
8. Singleton, H. Frequency Weighting Equations
http://www.cross-spectrum.com/audio/weighting.
html (accessed Jan 7, 2013).
Figure 1. Two-tone dissonance curve generated from
the two-tone dissonance formula. Frequency f is set to
440 Hz. The dashed line indicates the position of
gmax, the frequency value of g for which maximum
dissonance is generated.
9. Alabama High Field NMR Center. Piano Tuning
with Verituner http://daffy.uah.edu/piano/page4/
page8/index.html (accessed Jan 5, 2016).
APPENDIX
Full derivation of the maximum dissonance for two
pure tones
The dissonance formula
can be rewritten as
performing a substitution where
by
.5
Solution for the value of frequency g (gmax) that provides
maximum dissonance given frequency f, via calculus:
DOI: 10.13034 / JSST-2016-004
Figure 2. Graphical display of the calculated perceived
dissonance of a single note played on a piano, using
A-weighting. Perceived dissonance values between
the fundamental and all successive harmonics, in
every combination, are calculated and summed to
create the note’s final perceived dissonance score.
Calculations were performed for all C notes on the 88note keyboard.
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Figure 3. Single note dissonance was calculated as in Figure 2; however, the A-weighting was removed (A-weighting
parameter set to 0 in all calculations).
Figure 4. Image of the sound spectrum of the A2 note
on a Yamaha digital piano. The sound wave produced
by the piano is deconstructed into separate frequencies
(Hz) with the intensity of each frequency component
measured (arbitrary units).
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Figure 5. Image of the sound spectrum of the A5 note
on a Yamaha digital piano. The sound wave produced
by the piano is deconstructed into separate frequencies
(Hz) with the intensity of each frequency component
measured (arbitrary units).
DOI: 10.13034 / JSST-2016-004
SCIENCE FROM THE SOURCE
THE DEEP ROOTS OF THE ROCKY MOUNTAINS:
GEOPHYSICAL STUDIES OF WESTERN CANADA
Claire A. Currie
Department of Physics, University of Alberta, Edmonton AB, T6G 2E1, Canada
INTRODUCTION
The Rocky Mountains in western Canada have
some of the most spectacular scenery in the world,
with rugged terrain and snow-covered peaks. The
Rockies are part of the North American Cordillera, a
~4000 km mountain belt that runs along the western
side of North America (Figure 1). This mountain belt
formed over the last 200 million years, as rocks were
added to the western side of North America during the
convergence of tectonic plates. 1 As a result, the North
America plate has grown westward. Western Canada
can be divided into two main geological regions: (1)
the craton, which corresponds to the ancient core
of North America that has persisted for more than
1 billion years, and (2) the Cordillera mountain belt
consisting of younger accreted rocks. The geological
boundary between the two regions is marked by the
Rocky Mountain Trench and its northern extension,
the Tintina Fault. These appear as a linear zone of
low elevation along the eastern part of the mountains.
Figure 1: Surface topography in western Canada. Red
triangles indicate active volcanoes and thick black lines
mark tectonic plate boundaries, with plate names in italics.
JdF = Juan de Fuca.
As shown in Figure 1, the Cordillera and craton
regions have very different topographic expressions.
The Cordillera is characterized by high elevations
and rugged topography. In contrast, the craton region
DOI: 10.13034 / JSST-2016-005
is relatively flat and low-lying. The average Cordillera
elevation is about 1100 m and the average craton
elevation is about 350 m. Some mountainous terrain
extends up to 100 km east of the Rocky Mountain
Trench, corresponding to rocks that were emplaced
on top of the craton during plate convergence and
accretion.
This paper explores why the Cordillera sits 750 m
higher than the craton. To do so, geophysical data is
used to study the deep structure of the Earth. I first
encountered this topic when I was an undergraduate
student in geophysics. I had initially chosen to study
geophysics because I was interested in earthquakes.
Between my 3rd and 4th year of undergraduate
studies, I was fortunate to obtain a summer job with
the Geological Survey of Canada in Sidney, BC.
There, I worked with researchers studying Earth’s
structure and deformation on a range of timescales,
from earthquakes to long-term geological motions.
This broadened my perspective, and I realized that
there are many aspects of the dynamics of the Earth’s
interior that are poorly understood and that some
relatively simple observations (such as topography)
provide significant information about the complex
structure and processes occurring below the Earth’s
surface.
One of my supervisors at the Geological Survey of
Canada was Dr. Roy Hyndman (who would become
my Ph.D. advisor when I started graduate studies
the following year). At the time, he was analyzing
the relationship between surface topography
and subsurface structure in western Canada. He
demonstrated that the cause of the high elevations
in western Canada is not straightforward.2 This
intrigued me, and during my Ph.D., and in some of
my recent research, I have explored this topic in more
detail. This has involved the combination of various
geophysical observations, theoretical calculations
and computer models in order to understand the
structure of the upper ~300 km of the Earth and its
relationship to surface topography. In this paper,
I summarize some of this work and discuss some
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of my research experiences in
geophysics.
ISOSTASY AND SURFACE
ELEVATION
Variations in surface topography
in many parts of the world can
be explained using the idea of
isostasy. The upper part of the
Earth is divided into two main
layers: the low-density, silicarich crust and the high-density,
silica-poor mantle. According to
the theory of Airy isostasy, the
low-density crust “floats” on the
more fluid mantle, similar to an
iceberg floating on water. Just as
the height of the iceberg depends
on its thickness, isostasy states
that variations in crustal thickness
cause changes in surface
elevation. Thus, regions of high
elevation (e.g., mountains) should
correspond to areas of thick crust
and regions of low elevation
should have thinner crust.
As shown in Box 1, the relationship
between surface elevation (e) and
crustal thickness (h’c) is given by:
where ρc is the
density of the crust, ρm is the
density of the mantle, and hc is
the thickness of reference crust.
The reference crust is chosen
to be the crustal thickness that
results in elevations at sea level;
for the Earth hc is about 35 km.
To apply this equation, we use
typical densities of ρc=2850 kg/m3
and ρm=3300kg/m3.
Equation 1 predicts that if the
crust is thicker than 35 km, the
elevation will be positive (above
sea level); conversely thinner
crust should lie below sea level.
For example, if the crust doubles
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in thickness (h’c=70 km), the
expected elevation is 4.77 km.
This is comparable to the
observed elevation of the Tibetan
plateau (about 5 km above sea
level), where the crustal thickness
is 70-75 km. In contrast, the
average crustal thickness below
the oceans is 7 km. Equation 1
gives an elevation of -3.82 km,
which is similar to the average
seafloor depth, if the effect of
water weight is not included.
(i.e., the speed at which seismic
waves travel in each part of the
Earth’s interior). Seismic waves
travel more slowly through crustal
rocks than mantle rocks, and
therefore the interface between
the two layers can be mapped by
detecting the velocity change.
CRUSTAL THICKNESS AND
SURFACE ELEVATION IN
WESTERN CANADA
Does isostasy explain the contrast
between
the
high-elevation
Cordillera
and
low-elevation
craton in western Canada? To
answer this, we must measure the
thickness of the crust. However,
it is difficult to study crustal
thickness directly. To date, the
deepest borehole has reached
a depth of only 12 km (less than
0.2% of the Earth’s radius).
Therefore,
Earth
scientists
rely on indirect geophysical
measurements. In geophysics, we
use signals that are recorded at
the Earth’s surface to understand
the properties of the material
below the surface. Seismic waves
are one of the most widely used
tools, as these waves travel
through the Earth’s interior and
carry information about all the
material they have encountered.
An important parameter is the
velocity of the seismic waves.
By measuring the travel time
of seismic waves from distant
earthquakes to seismic stations,
it is possible to determine spatial
variations in seismic wave velocity
Figure 2: Thickness of the crust in
western Canada from observations
of seismic waves3. The dashed red
line marks the location of the Rocky
Mountain Trench / Tintina Fault.
Figure 2 shows the crustal
thickness for western Canada
based on an analysis of seismic
waves.3 The crustal thickness
varies between about 25 km
and 50 km below the continental
region. Interestingly, the Cordillera
does not correspond to the areas
of thickest crust, as would be
expected for a mountain belt.
The average crustal thickness
for the Cordillera is 33.6 km,
which is 3 km thinner than the
craton crust (average 37.6 km).
For comparison, Equation 1
predicts that the Cordillera crustal
thickness should be 43.1 km in
order to explain the observed
average elevation of 1100 m.
Another way to look at this is
to use the observed crustal
DOI: 10.13034 / JSST-2016-005
thicknesses
(Figure
2)
to
calculate the expected surface
elevation, assuming Airy isostasy.
The result is shown in Figure 3.
For much of western Canada,
the craton region has a predicted
elevation similar to the observed
elevation. The discrepancies in
the northern and southern parts
of the craton can be resolved by
considering variations in crustal
density. On the other hand, the
thin Cordillera crust is predicted
to result in elevations that are on
average 200 m below sea level
for much of British Columbia and
not a high-elevation mountainous
region!
Figure 3: Predicted surface elevation
in western Canada, based on the
observed crustal thickness. The
dashed red line marks the location of
the Rocky Mountain Trench / Tintina
Fault.
From these calculations, we
find that the observed Cordillera
elevation is about 1300 m higher
than predicted for its crustal
thickness. It should be noted
that these calculations assume
a constant composition (and
therefore density) for the crustal
layer. In a more detailed study
that included data for all of North
America, we found that when
compositional variations are
included, the Cordillera elevation
is 1600 m higher than expected. 4
DOI: 10.13034 / JSST-2016-005
MANTLE STRUCTURE
WESTERN CANADA
IN
MANTLE
TEMPERATURE
AND SURFACE ELEVATION
Based on the above results, we
cannot explain the Cordillera
elevation by thick crust. Therefore,
we must look deeper in the Earth.
Geophysical observations can
be used to study the mantle, the
layer of rock below the crust.
Detailed observations of seismic
wave travel times can be used to
map small variations in velocity
within the mantle and learn about
the properties of this layer.
Within the Earth’s mantle, the
main control on the seismic
wave velocity is the temperature
of rocks; factors such as
compositional variations are
secondary. It is possible to use
theoretical studies to calculate
how seismic wave velocity
varies with temperature e.g.,6,7.
Figure 5 shows the relationship
between shear wave velocity and
temperature for a typical mantle
composition at 90 km depth. With
increasing temperature, the wave
velocity decreases as the rocks
become less able to transmit the
seismic disturbance.
Figure 4: Seismic shear wave
velocity at 90 km depth below
western Canada. The dashed red
line marks the location of the Rocky
Mountain Trench / Tintina Fault.
Figure 4 shows a map of the
seismic shear wave velocity at
a depth of 90 km below western
Canada.5 In western Canada,
shear wave velocities vary
between 4100 m/s and 4900
m/s. There is a clear difference
in velocity below the Cordillera
and craton regions. The craton
has a relatively high velocity
(average 4739 m/s), compared to
an average velocity of 4344 m/s
for the Cordillera. The boundary
between high and low velocity
corresponds closely with the
Rocky Mountain Trench / Tintina
Fault.
The theoretical relationship in
Figure 5 can be used to convert
the observed seismic velocities in
western Canada (Figure 4) into a
map of mantle temperature. This
is shown in Figure 6. The low
velocities below the Cordillera
mountain belt indicate high
mantle temperatures, with an
average of 1258ºC. In contrast,
Figure 5: Variation in shear wave
velocity with temperature at 90 km
depth (black line). The average
velocity (and standard deviation) for
the craton and Cordillera are shown
in blue and red, respectively.
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Figure 6: Calculated temperature
at 90 km depth below western
Canada. The dashed red line marks
the location of the Rocky Mountain
Trench / Tintina Fault.
Figure 7: Variation in average
temperature with depth for the
Cordillera (red line) and craton (blue
line). The shaded region shows
the standard deviation. Mantle
temperatures were calculated based
on observed seismic velocities;
crustal temperature are from an
analysis of surface heat flow8.
lower temperatures are predicted
for the craton region, where the
average temperature is 583ºC.
I have done a similar calculation
to convert seismic velocities into
temperatures at depths from 70
km to 250 km for western Canada.
At all depths, the seismic wave
velocities in the Cordillera mantle
are less than those in the craton
38
2016 VOL 9
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Figure 8: Schematic cross-section through southwestern Canada. Hydration
of the mantle below the Cordillera may enable convection that carries heat into
this region and provides the buoyancy to support the high elevations below the
mountain belt.
mantle, and the Cordillera mantle
is predicted to be hotter. Figure 7
shows the average temperature
as a function of depth for both
regions. These new temperature
calculations
are
in
good
agreement with my previous
work8, and they confirm that the
Cordillera and craton regions have
distinct temperature structures.
The temperature difference is
largest at shallow mantle depths
and decreases with depth. There
is little difference between the two
areas below about 220 km depth.
The
temperature
difference
has important implications for
surface topography. As rocks are
heated, their density decreases
through thermal expansion. For
a temperature change of ΔT, the
rock density is: ρ = ρ0 (1 – α ΔT)
where ρ0 is the reference mantle
density (3300 kg/m3) and α is the
thermal expansion coefficient (3
x 10-5 K-1 for mantle rocks). From
Figure 6, the Cordillera mantle is
an average of 300ºC hotter than
the craton mantle to a depth of
220 km. This suggests that the
density of the Cordillera mantle is
3270 kg/m3 (30 kg/m3 less dense
than craton mantle).
In
the
previous
isostasy
calculations 1, it was assumed
that the density of the crust
and mantle are the same for all
regions. However, the seismic
observations show that the
Cordillera mantle is less dense
than craton mantle because it is
hotter. The equations in Box 1
can be modified to include this
density difference. With this, we
find that the predicted elevation
of the Cordillera is about 1500 m
above sea level,4 which is similar
to the observed elevation.
GEODYNAMICS OF WESTERN
CANADA
The geophysical observations
presented above show that
the Cordillera mountain belt in
western North America is unusual.
Whereas many mountain belts,
such as the Tibetan Plateau,
have high elevation because of
a thick, low-density crust, the
Cordillera crust is anomalously
DOI: 10.13034 / JSST-2016-005
Box 1: Airy Isostasy
The diagram on the right shows how the isostasy equation is
derived. First, consider the reference column of material that is
made of a crustal layer (thickness hc and density ρc) and mantle
layer (thickness hm and density ρm). The weight of this column is
given by the pressure at point P1:
P1=ρcghc + ρmghm where g is the gravitational acceleration (9.81
m/s2). Point P1 is placed at the compensation depth, which is the
depth at which the mantle becomes hot and weak enough to flow
very slowly (a few cm/yr) over millions of years.
Now consider a region with a thicker crust (thickness h’c). If the
excess crustal thickness is simply added to the top of the reference
crust, the pressure at the compensation depth increases. Airy
isostasy says that the deep mantle rocks will slowly flow outward
due to the high pressure, and flow will stop once the pressure at
the base of this column is equal to that in the reference column.
This condition is called isostatic equilibrium. As a result, the thick
crust sinks and displaces some of the underlying mantle. At the
time of isostatic equilibrium, the thick crust will sit at an elevation
(e) higher than the reference column, and it will have a root (r)
that extends to larger depths into the mantle. The new mantle
layer thickness is h’m and the pressure at the compensation depth
for this column is:
P2=ρcgh’c + ρmgh’m
At this point, the two columns are in isostatic equilibrium (P1=P2) and therefore:
ρcghc + ρmghm = ρcgh’c + ρmgh’m
From the figure, we see that:
h’c = e + hc + r and
h’m = hm - r = hm - (h’c - e - hc) = hm - h’c + e + hc
These equalities can be substituted into the previous equation, allowing it to be rearranged into an equation that gives the
predicted elevation (e) as a function of crustal thickness (hc’):
ρcghc + ρmghm = ρcgh’c + ρmghm - ρmg h’c + ρmg e + ρmghc
ρchc = ρch’c - ρmh’c + ρme + ρmhc
ρm(h’c - hc) = ρc(h’c - hc) + ρme
thin. Instead, the high elevations
in this mountain belt appear to
be supported by the hot, lowdensity mantle. Figure 8 shows
a
schematic
cross-section
through southwestern Canada,
emphasizing the decrease in
surface elevation, increase in
crustal thickness and increase
DOI: 10.13034 / JSST-2016-005
in mantle temperature from the
Cordillera to the craton.
Why is the Cordillera mantle so
hot? During my Ph.D. research,
we proposed that this may be
related to the plate tectonic
setting of this region.8 For the last
200 million years, the western
side of North America has been
an area where oceanic plates
(such as the modern Juan de
Fuca plate in Figure 1) converge
and descend below the continent,
a process called subduction.
During descent, water within the
plate is released and hydrates
the overlying material, resulting in
a low viscosity for the Cordillera
2016 VOL 9
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39
mantle. We speculate that the
low viscosities enable this mantle
to undergo convection and that
this efficiently carries heat from
deep Earth to the shallow mantle.
Computer models show that
our proposed idea may work9;
however, many details are still
not understood.
CONCLUSIONS
In geophysics, we aim to gain
a quantitative understanding of
the structure and dynamics of
the Earth’s interior. In this paper,
I have shown how geophysical
observations allow us to study
the deep structure of the craton
and Cordillera regions in western
Canada. At the surface, the
craton is clearly distinct from
the Cordillera. The craton is
composed of relatively old rocks
and has an elevation <500 m
above sea level. In contrast, the
Cordillera contains younger rocks
and sits >1 km above sea level.
To understand the origin of the
elevation difference, geophysical
methods can be used to examine
the structure of the subsurface.
This paper has highlighted two
important observations that come
from the analysis of seismic
waves: (1) the Cordillera crust is
3 km thinner than the craton crust,
and (2) the Cordillera mantle
is 300ºC hotter than the craton
mantle to a depth of 220 km. The
observations show that the high
elevations in the Cordillera region
are not due to the presence of an
anomalously thick, low-density
crust. Rather, it appears that the
high mantle temperatures result
in low densities that buoyantly
support the mountain belt.
40
2016 VOL 9
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MY EXPERIENCES IN GEOPHYSICS
In
this
article,
I
have
highlighted how geophysical
observations can be used to
study the internal structure of
the Earth. This is one aspect
of my research. The other
aspect is trying to understand
the dynamics of the Earth’s
interior. Geophysical observations
provide a “snapshot” of the
current structure, and so I use
computer models and theoretical
calculations to understand the
dynamical processes that occur
within the Earth and assess their
effects on surface geology.
The goal of my research
is to put the observations
and models together into a
coherent understanding of the
factors that control the evolution
of the Earth. What I like most
about my work is that I use a
wide range of tools to solve “big
picture” problems, such as the
development of mountain belts.
This is also challenging because
I must understand the methods
used to collect each data set
and the details of the model
calculations. Much of my work
is carried out in collaboration
geophysicists and geologists who
have collected the data that I am
using. Through the collaborations,
I am always learning new things.
Each person brings a different
perspective to the collaboration,
which can lead to new ideas and
research directions.
I am currently an associate
professor in geophysics at the
University of Alberta. To reach
this point, I had a relatively
straightforward path, as I started
my
undergraduate
degree
knowing that I wanted to study
geophysics. I completed at B.Sc.
in geophysics at the University
of Western Ontario and a Ph.D.
in geophysics at the University
of Victoria. I then spent 2.5 years
as a post-doctoral researcher at
Dalhousie University. In contrast,
many people who become
geophysicists do not discover
their interest in the field until later
in their undergraduate studies,
perhaps after taking an Earth
sciences course as an elective.
Geophysics is offered as a B.Sc.
degree at several universities
in Canada. Alternatively, it is
possible to complete a B.Sc.
degree in physics or Earth
sciences (geology), and then
specialize in geophysics through a
graduate degree (M.Sc. or Ph.D.).
For people interested in pursuing
geophysics, it is necessary to
have a strong background in the
physical sciences (e.g., physics,
math, chemistry). As well, it is
important to develop skills in
computer programming, scientific
writing and public speaking;
these are essential for almost any
career in the sciences.
There are different career
options in geophysics. The
majority of geophysicists work
in the petroleum or mining
industries, where they conduct
field trips to collect data or work
on computers to analyze and
interpret the data. Geophysicists
can also work in other industries
(e.g., environmental monitoring,
geotechnical consulting, natural
hazard assessment) or as
researchers at a university or
government lab.
My job at the University of
Alberta involves a combination
DOI: 10.13034 / JSST-2016-005
of research and teaching. In
addition to my own research
projects, I teach undergraduate
courses in geophysics, and I
work with undergraduate and
graduate students on research
projects. A significant part of
my current work is to continue
the research in this paper. My
students and I are now analyzing
different types of geophysical
data, such as measurements of
the electrical structure, in order
to better constrain the mantle
structure in western Canada. We
are also working on computer
models to understand the links
between mantle convection,
thermal structure and surface
elevation. In addition, we are
looking at the consequences
of the temperature contrast
between the Cordillera and
craton. For example, temperature
controls the strength of rocks,
and therefore the hot Cordillera
is relatively weak and prone
to earthquakes and geological
deformation. In contrast, the
craton is cold and strong and will
be earthquake-free, except at
zones of weakness.
REFERENCES
1. Monger, J.W.H.; Price, R.A.
The Canadian Cordillera:
Geology
and
tectonic
evolution, CSEG Recorder,
February 2002, 17-36.
2. Hyndman, R.D.; Lewis, T.J.
Geophysical consequences of
the Cordillera-craton thermal
transition in southwestern
Canada.
Tectonophysics,
1999, 306, 397-422.
DOI: 10.13034 / JSST-2016-005
3. Kao, H.; Behr, Y.; Currie,
C.A.;
Hyndman,
R.D.;
Townend, J., Lin, F.C.;
Ritzwoller,
M.H.;
Shan
S.J.; He, J. Ambient seismic
noise tomography of Canada
and adjacent regions: Part
1. Crustal structures. J.
Geophys. Res. 2013, 118,
5865-5887.
9. Currie, C.A.; Huismans,
R.S.; Beaumont, C. Thinning
of
continental
backarc
lithosphere by flow-induced
gravitational instability. Earth
Planet. Sci. Lett. 2008, 269,
436-447.
4. Hyndman, R.D.; Currie,
C.A. Why is the North
America Cordillera high? Hot
backarcs, thermal isostasy,
and mountain belts. Geology,
2011, 39, 783-786.
5. Bedle, H.; van der Lee,
S. S velocity variations
beneath North America. J.
Geophys. Res. 2009, 114,
doi: 10.1029/2008JB005949.
6. Cammarano,
F.;
Goes,
S.; Vacher, P; Giardini,
D, Inferring upper-mantle
temperatures from seismic
velocities. Phys. Earth Planet.
Inter. 2003, 138, 197-222.
7. Goes, S.; Armitage, J.;
Harmon, N.; Smith, H.;
Huismans, R. Low seismic
velocities below mid-ocean
ridges: Attenuation versus
melt retention. J. Geophys.
Res.
2012,
117,
doi:
10.1029/2012JB009637.
8. Hyndman, R.D.; Currie,
C.A.;
Mazzotti,
S.P.
Subduction zone backarcs,
mobile belts, and orogenic
heat. GSA Today. 2005, 15,
4-10.
2016 VOL 9
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41
SCIENCE FROM
FOR THE
THESOURCE
SOURCE
BUILDING ON SCIENCE: MY CAREER (SO FAR) IN CELL
RESEARCH
Justin Parreno1, 2
1. Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, ON, M5G 1X5
2. The Scripps Research Institute, La Jolla CA, 92037
THE BACHELOR’S DEGREE – ENTERING
THE SCIENCES
Growing up, I always wanted to become a medical
doctor. Like many young students pursuing medicine,
I entered my undergraduate degree in the biological
sciences. The science courses were a struggle for
me to get through and I found myself even more
interested in my option courses such as psychology
or even economics. Nevertheless, I finished my
biological sciences degree. I did apply to medicine but
did not get in, so I decided to get a master’s degree
in order to improve my curriculum vitae in hopes of
eventually getting into medicine.
THE MASTER’S DEGREE – ENTERING THE
SCIENCES
When deciding which research area to pursue for my
master’s degree, I gravitated toward bone and joint
research based on my involvement in playing sports
growing up. I met with several different scientists at
the Bone and Joint Institute (formerly called the Joint
Injury and Arthritis Research Group) at the University
of Calgary, and chose to work in the laboratory of Dr.
David A. Hart. The first task I was given by the principle
investigator was to choose a particular project to work
on. I was given several different scientific papers to
read, which turned out to be a daunting task. Despite
having a strong science background, I struggled with
those papers, getting lost in the scientific jargon.
Nevertheless, based on what I could glean from those
papers, the area of bone cell mechanotransduction
seemed interesting to me. Mechanotransduction is
aimed at understanding how cells sense, transduce,
and respond to mechanical loading. It is the process
that can explain why weightlifters have increased
bone mass whereas astronauts have decreased
bone mass.
My
mechanotransduction
research
focused
specifically on how the bone forming cells,
osteoblasts, respond to different types of mechanical
loading. I would apply different loading modalities onto
42
2016 VOL 9
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cells, such as stretching or compressing cells using
special instrumentation. From my studies we found
that osteoblasts not only responded to mechanical
loading by regulating the expression of genes, but
they also responded by physically modifying their
environment. In other words, osteoblasts, which are in
a collagen matrix, are able to reorganize collagen by
pulling on it. This pulling force was established by the
cytoskeleton, which is the structural framework of the
cell. Two major components of the cytoskeleton are
actin and tubulin. Actin and tubulin are similar to the
molecular cables and struts of a bridge – they provide
cellular architecture. Without proper organization of
actin, the pulling force exerted by the cells on the
collagen matrix is diminished, reducing the potential
for matrix remodelling.1, 2 Insufficient remodelling
forms the basis of several bone pathologies such as
non-union healing of bone and osteoporosis.
My master’s degree allowed me to perform real
research through which I was actually able to
Figure 1: Cell mediated contraction of collagen gels. Top
view of gels within a culture dish. Cells are placed within
a collagen solution, which gels when placed in a 37oC
incubator. After 48 hours, the gels are detached from the
sides of the culture dish. The cells that are within the gels
contract the collagen gels as shown in Panel A. However,
this contraction is dependent on actin as treatment of
cells in collagen with actin inhibitor (latrunculin B) prior to
detachment prevents collagen gel contraction as shown in
Panel B. Dashed lines represent perimeter of gels.
DOI: 10.13034 / JSST-2016-006
contribute to the world’s wealth of
scientific knowledge. I was even
given the opportunity to present at
scientific conferences and publish
my findings scientific journals.
These experiences left me thirsty
for knowledge and hungry for
more research.
THE PH.D. – NO LOOKING
BACK
After completing my master’s
degree, I wanted to further
advance my research expertise by
embarking on a Ph.D. I discussed
this interest with my master’s
degree supervisor. He urged me
to pursue research away from the
University of Calgary as this was
where I did my master’s degree
and a change in the research
environment would be an asset
in terms of my career. Through
my exploration of other areas of
research, I became intrigued by
bioengineering, which involves
developing replacement body
parts using a patient’s own cells.
This interest inspired me to move
to Toronto to work with Dr. Rita
Kandel, a pioneer in articular
cartilage bioengineering research.
Articular cartilage is the white
glistening tissue that resides on
the top ends of bone joints and
provides a nearly frictionless
surface for joint movement.
Unlike other tissues, such as
bone or skin, articular cartilage is
incapable of self-repair. Damage
to articular cartilage results in
progressive degradation and, as
a consequence, joint replacement
is often necessary. Replacements
consist of replacing cartilage
with
metal/plastic/ceramics,
which have a limited lifespan
and eventually require revision.
DOI: 10.13034 / JSST-2016-006
Thus,
these
replacements
are not optimal and patients
would certainly benefit from
bioengineered articular cartilage.
Articular cartilage has a unique
composition.
Two
essential
molecules present in cartilage
matrix are proteoglycans and
collagens. The cartilage cells,
which are called chondrocytes,
mainly produce the proteoglycan
aggrecan and type II collagen;
these molecules are essential
for
cartilage
to
withstand
mechanical loads. A major aim
in bioengineering cartilage is to
produce tissue that approximates
articular cartilage with high
expression of these molecules.
In
1995,
a
breakthrough
study showed that culturing
chondrocytes at high density in
three-dimensional culture could
result in the generation of articular
cartilage tissue.3 Importantly,
this study demonstrated that
bioengineering
of
articular
cartilage was possible.
human joint. To accomplish this,
a large number of chondrocytes
capable of depositing matrix rich
in type II collagen and aggrecan
are
needed.
Unfortunately,
chondrocytes are limited in number.
Chondrocytes can be placed in
culture dishes to proliferate and
increase the number of cells.
However, expanded cells undergo
a process of dedifferentiation,
which results in the failure of
cells to express cartilage matrix
and they express high levels of
type I collagen instead. This is
indicative of fibrocartilage, which
is inferior to articular cartilage
and is incapable of meeting the
mechanical demands of the joint.
For my research, I was tasked
with finding out what regulates
this dedifferentiation process
in chondrocytes. The first thing
I noticed when I looked in the
microscope was the stark contrast
in the sizes and shapes of the
cells. Initially chondrocytes were
small and round, but after a few
At this point, a lingering issue in the
field of bioengineering was how
to scale up to replace an entire
Figure 2: Confocal microscopy
images of freshly isolated primary
chondrocyte and culture expanded
passaged cells stained for F-actin
using
FITC-phalloidin.
Primary
chondrocytes are smaller and have a
cortical distribution of actin whereas
passaged chondrocytes have actin
organized into stress fibers throughout
the cytoplasm. Scale bar = 10um.
Figure 3: Control of type I
collagen
gene
expression
through the actin polymerization
in
passaged
chondrocytes.
Passaged chondrocytes contain
a high proportion of F-actin. Actin
depolymerization through latrunculin
B treatment increases G-actin
monomer concentration. G-actin
attracts MRTF and pulls MRTF from
the promoter CArG promoter regions
of type I collagen and brings it into the
cytoplasm of the cells. This supresses
gene expression of type I collagen.
2016 VOL 9
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43
days
chondrocytes
became
larger and began to spread out.
From my previous studies, I knew
that the cellular cytoskeleton
could regulate this change in cell
size and shape. Upon further
investigation of the literature, I
discovered that it was initially
demonstrated
over
several
decades ago that the actin
cytoskeleton could regulate the
production of cartilage matrix.
But the molecular mechanisms
by which the cell did this were still
was unclear. So it became my
objective to find the connection
between the actin cytoskeleton
and matrix gene expression.
Work being performed in other
types of cells had shown that
a transcription factor called
myocardin-related transcription
factor-a (MRTF) could regulate
the expression of type I collagen.
4 MRTF, when inside the nucleus
of cells, binds to the promoter
regions of genes and drives the
expression of certain genes such
as type I collagen. MRTF can also
bind actin. Actin could exist as
monomeric, globular (G-) actin,
which can polymerize to form
filamentous (F-) actin and MRTFa
has a high affinity to G-actin.
When F-actin is depolymerized
into G-actin, MRTF binds to
the G-actin, is exported from
the nucleus to the cytoplasm,
and gene expression could be
decreased.
Based on these findings in
other cell types, the hypothesis
for my project formed: Actin
polymerization regulates type
I collagen gene expression in
passaged chondrocytes through
MRTF. To test this hypothesis I
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2016 VOL 9
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first measured G-/ F-actin and
MRTF localization in primary
and passaged chondrocytes.
In support of my hypothesis,
I found that there was more
G-actin (less F-actin) in primary
chondrocytes as compared to
passaged chondrocytes. 5 Next
I examined the effect of actin
depolymerization on passaged
cells in increasing the proportion
of G-actin. I treated passaged
chondrocytes with an actin
depolymerization drug and found
that not only did this increase
the proportion of G-actin but it
also resulted in MRTF export
to the cytoplasm and reduced
type I collagen expression. The
last piece of support for my
hypothesis was the finding that
inhibiting MRTF decreased type
I collagen gene expression.
Thus, actin regulated type I
collagen through MRTF. This
research indicated that MRTF
regulation should be considered
for improving bioengineering of
articular cartilage.
I completed my project, defended
my thesis, published my work
5-7 and graduated with my Ph.D.
However, I still have that hunger
for more research. The next step
for me is to complete a postdoctoral research fellowship to
gain more scientific expertise,
which is often a required
step before starting up as an
independent researcher. I have
decided to gain further expertise
in actin research. For this
pursuit, I will be heading to The
Scripps Research Institute in San
Diego, California to a renowned
actin
research
laboratory.
Although I will not be working in
musculoskeletal research there (I
will be conducting eye research),
I would like to one day bridge the
expertise I gain and apply it in
musculoskeletal research. I hope
to eventually return to Canada to
start my own research lab.
MY ADVICE FOR STUDENTS
Pursue what interests you
There is a world of opportunity, so
do the things that interest you. For
me it was bone and joint research.
Look at what research is currently
being done at institutions in your
area. Contact researchers at the
labs that interest you and speak
with them about potential projects.
When you go to speak with
them, be prepared; for example,
demonstrate your interest in
their lab by reading some of their
published research papers. Also,
make sure you jive with your
potential supervisor. You can get
a sense of their personality by
speaking with them and other
people in their lab.
Start early
I entered the world of research
relatively late. Many labs accept
undergraduate
students
for
small research projects during
the summer or for course credit
during the school year. Some
even accept high school students.
So look for these opportunities.
If you find a laboratory you are
interested in, it does not hurt to
contact them to see if there is
opportunity for you to do work
there.
Read, read, read
Although it is very daunting at first
to read a scientific paper, mainly
because of the jargon, you will
DOI: 10.13034 / JSST-2016-006
eventually understand and even
begin to use this jargon. It will be a
new language to you and will take
time to learn, so keep at it. Know
what research has been done in
your field, and find studies that are
comparable to your own research,
so that you do not get stuck trying
to reinvent the wheel. In addition,
read papers from outside of your
field. Other fields of expertise
can give inspiration for your own
work. For me, the research being
performed in vascular research
gave me insight to my cartilage
project.
Consult with others
Others have tackled the same or
similar problems that you face, so
speak with them. When you start
in the lab you will have to learn
methodology and how to perform
certain experiments. Often other
lab members can provide some
guidance, so don’t be afraid to
ask them for help. When they
do teach, make sure to listen
and take good notes. Along with
asking specific questions about
your research, consult with others
about the ‘big’ decisions, like the
decision to do another degree
or post-doc. Make a point to
develop good relationships with
your supervisors. I was lucky to
develop great relationships with
both my master’s and doctoral
supervisors. For instance, my
master’s supervisor guided me in
choosing my doctoral supervisor.
Subsequently both my master’s
and doctoral supervisor gave
some advice on which lab to select
for my post-doctoral research.
Remember that these people can
only provide you with advice, but
ultimately these decisions come
DOI: 10.13034 / JSST-2016-006
down to you. Nonetheless, it can
certainly be helpful to hear their
opinions. For me, my previous
supervisors continue to act as
my mentors and have been
fundamental to my development
and success.
Don’t be afraid to try something
new
During your research you will
invariably ask questions to which
no one has the answers. To me,
the exciting part of research
is answering those types of
questions. Along the way you may
encounter naysayers that want to
discourage you from attempting
something new in your research,
but try to ignore them. Discovering
and observing something no
one has observed before has to
be one of the most exhilarating
feelings. Enjoy it and never stop
asking questions.
REFERENCES
1. Parreno, J.; Buckley-Herd,
G.; de-Hemptinne, I.; Hart,
D. A. Osteoblastic MG-63 cell
differentiation,
contraction,
and mRNA expression in
stress-relaxed 3D collagen
I gels. Mol. Cell. Biochem.
2008, 317, 21-32.
2. Parreno, J.; Hart, D. A.
Molecular and mechanobiology of collagen gel
contraction mediated by human
MG-63 cells: involvement
of
specific
intracellular
signaling pathways and the
cytoskeleton. Biochem. Cell
Biol. 2009, 87, 895-904.
during
formation
of
cartilagenous tissue in vitro.
Osteoarthr. Cartil. 1995, 3,
117-25.
4. Small, E. M.; Thatcher,
J. E.; Sutherland, L. B.;
Kinoshita, H.; Gerard, R. D.;
Richardson, J. A.; Dimaio,
J. M.; Sadek, H.; Kuwahara,
K.; Olson, E. N. Myocardinrelated transcription factor-a
controls
myofibroblast
activation and fibrosis in
response
to
myocardial
infarction. Circ. Res. 2010,
107, 294-304.
5. Parreno, J.; Raju, S.; Niaki,
M. N.; Andrejevic, K.; Jiang,
A.; Delve, E.; Kandel, R.
Expression of type I collagen
and tenascin C is regulated by
actin polymerization through
MRTF in dedifferentiated
chondrocytes. FEBS Lett.
2014, 588, 3677-84.
6. Parreno, J.; Cruz, A. V.
Accelerated aging in patients
with
Hutchinson-Gilford
progeria syndrome: Clinical
signs, molecular causes,
treatments, and insights into
the aging process. UBCMJ
2011, 3, 8-12.
7. Parreno, J.; Delve, E.;
Andrejevic, K.; Paez-Parent,
S.; Wu, P.-h.; Kandel,
R.
Efficient,
Low-Cost
Nucleofection of Passaged
Chondrocytes. Cartilage 2015.
3. Boyle, J.; Luan, B.; Cruz, T. F.;
Kandel, R. A. Characterization
of proteoglycan accumulation
2016 VOL 9
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SCIENCE FOR
TEACHING
RESOURCES
THE SOURCE
THE WATER PROJECT
By Shantel Popp
ABSTRACT
This resource was created to embark on a STEM project in grade 8 science class. Students are exposed to
four different units during the year in Ontario, including: Cells, Fluids, Systems in Action, and Water Systems.
The learning objective was to create a project that linked each of these units together under a “systems” theme
and incorporate engineering, math, and technology. Students were able to showcase their learning in a final
presentation that highlighted the different components of the STEM project. This includes the pulley schematics,
design, and calculations of their water filter and technology implementation. This project uses Google Apps for
Education so students can collaborate on the project synchronously and asynchronously, as well as incorporates
hard skills like using a microscope, and provides students with the opportunity to design and build techniques.
Cette ressource a été créée pour s’embarquer en un projet de STIM en utilisant comme guide le curriculum de
science ontarien de la 8e année. Les étudiants apprennent à propos quatre sujets différents pendant l’année
scolaire, incluant Les Cellules, Les Fluides, Les Systèmes en Action, et les Systèmes Hydrographiques. L’objectif
d’apprentissage était de créer un projet qui liait tous ces sujets ensemble sous un thème commun, les systèmes,
et intégrerait aussi l’ingénie, les mathématiques, et la technologie. Les étudiants ont eu la chance de montrer les
connaissances qu’ils ont apprises dans une présentation finale qui a souligné les éléments différents du projet.
Cela inclut les moufles, la conception, les calculs de leur filtre à eau et l’implémentation de la technologie. Ce
projet utilise ‘Google Apps for Education’ pour que les étudiants puissent collaborer sur le projet en synchronie
et seule. Il incorpore aussi les compétences du niveau plus élevé, comme l’utilisation d’un microscope et donne
les étudiants la chance de développer les stratégies et techniques de la conception et construction.
INTRODUCTION
My teaching partner and I were really motivated to
create something engaging for our students with
regards to the grade 8 water systems unit. We wanted
to also build a project that was connected across the
units we had studied throughout the course of the
year in order to prepare for year end exams. This
project is the product of that thinking and, based
on student feedback, the project has evolved into
something that students really can connect to as
citizen scientists. This is a STEM project that asks
students to design a pulley and build an actual water
filter that could be used in the early treatment of a
dirty water sample. The project is a resource for other
educators to shape into something that they can
recreate in their own classroom. It takes the learning
from the water systems unit, and brings in the fluids,
cells, and systems in action units from the Ministry of
Ontario Grade 8 Science and Technology Curriculum
document.
LEARNING OBJECTIVE(S)
Scientific Method
Understanding the scientific method is a key
component to this project. All year, students have been
exposed to lab reports, including their formatting, style,
and content. With this project, the scientific method
is put into the hands of students as they design the
questions, hypothesis, materials, procedure, and
conclusion.
Lab Skills
Students work on lab skills by designing and building
their own water filter. They also have to test their
design and implement any solutions they deem
necessary. Group members also must document and
record the data they collect in an organized way using
a shared Google Doc.
Curriculum Expectations
The big ideas for the grade 8 water systems unit are
to have students understand that water is crucial to life
on earth, that water influences climate and weather
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patterns, and that water is an
important resource that needs to
be managed sustainably.
challenge students to think about
principles of density in sanitization,
a connection to the Fluids unit.
The overall expectations for the
water systems unit are:
In the design of this project, we
really needed to consider as
teachers the overall expectations
for this unit. When trying to design
something that demonstrates
the sustainability of water as
a resource, we thought it was
important to set the stage of the
project in a developing country for
students, to a region where water
doesn’t just flow freely out of the
taps everywhere. This is also why
we thought that including the idea
to create a pulley system to “fetch”
the water out of well was vital for
this project. Thinking about the
idea of sustainability, the project
also aims to connect the idea of
gathering and sanitizing water as
an important project and to be
mindful of ‘waste water.’
1. assess the impact of human
activities and technologies
on the sustainability of water
resources;
2. investigate factors that affect
local water quality;
3. demonstrate an understanding
of the characteristics of the
earth’s water systems and the
influence of water systems on
a specific region.
The Hidden Curriculum
Even though these expectations
are certainly met during the course
of this project, there emerges some
deeper abilities as the hidden
curriculum including collaboration,
critical thinking, and problem
solving. These skills are critical
for students as they develop a
solid foundation in STEM abilities
with this project. For example,
understanding group dynamics,
division of labor and team work
are all aspects of the collaborative
process that students need to
negotiate during the course of this
project.
EDUCATIONAL DESIGN
This project connects the
principles of STEM to the four
units that are in the grade 8
Ontario science curriculum. When
we ask students to investigate
microscopic organisms in water,
we are challenging them to think
about the Cell unit. Students then
need to design a pulley system to
collect water, a connection to the
Systems in Action Unit. Finally, we
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When thinking about the idea of
what are the factors that affect
local water quality, we decided
to think about the different things
that could be found in water - from
living microscopic organisms to
dirt.
We wanted students to think
deeply about the influence of water
systems in specific regions of the
world. During the course of the unit,
students have completed a water
audit on their own consumption of
water, and thus have information to
compare with their research. This
is important when they are thinking
about the developing country for
which they are designing a filter
because they are able to compare
and contrast their own research
findings with research regarding
their design and implementation
of the filter.
FORMAT FOR
EVALUATION
STUDENT
Students need to create a full
lab report in their groups. In this
report, students will document
their process and product, and
how the water filter effectively (or
ineffectively) cleaned the water
sample. Students are provided
a basic outline for what the lab
report needs to look like and then
are challenged to fill in the blanks
using research, prior knowledge,
and aspects of the experiment.
Students are evaluated using a
rubric with knowledge, inquiry,
communication, and application.
The lab report structure allows
for students to showcase
knowledge on pre lab questions
and observations of how well
their water filter cleans a dirty
sample. Testing and the procedural
writing of the actual lab itself falls
into inquiry and communication.
Application is showcased when
students are able to analyze and
interpret their results in a way that
clearly expressed their findings,
and implications to the users of
the filter.
PROGRAM EVALUATION
1)
Reaction (required)
- Students enjoy doing the
hands-on aspect of the
project, and designing
something that is uniquely
their own.
- Students were motivated
to create a filter that would
provide the cleanest water
sample at the end of the
experiment and their reaction
after each trial really showed
their dedication to this
process.
2016 VOL 9
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-
2)
Students question the
design of the filter, and must
reflect on its true relevance
in the real world. Since
no chemicals are added,
students must document
what further filtration steps
would be required to truly
make the water clean.
Learning (required)
- Students learned that much
of the world does not have
access to clean drinking
water, and that the overuse
of freshwater in developed
countries is impacting the
planet.
-
Students
deve loped
knowledge of the scientific
method, fair trials, and
foundational knowledge
about how natural water
filtration takes place.
-
Students
worked
collaboratively to problem
solve and create the best
solution to filtering the dirty
water.
- Since the lab report includes
both pre lab questions,
and post lab reflection and
analysis, student growth and
understanding could be seen
in a concrete way.
3)
Behaviour/Performance
(optional)
-
48
Students apply their
knowledge of the unit,
and past units in order to
effectively design and build
their filter. They are also
very open to sharing tips
and techniques with other
groups. Their mindset is
definitely a growing one, as
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they take risks and attempt to
restructure their experimental
designs if it doesn’t work.
DISCUSSION
What I have found interesting
about this project is how invested
students become at creating a
functional water filter, and the
research they do to seek out the
proper materials. Most importantly,
this project does indeed meet the
expectations set out by the Ministry
as well as additional skills and
abilities in science. The examples
of student work below show
the level at which they created
designs, observation tables, and
calculations of their results. There
are many indicators of this during
the project that notably engages
students in a hands-on project
that incorporates technology,
engineering, and math while in
science class. A shortcoming of
this project, is that students don’t
have access to actual chemicals
to help clean their water at the end
of the filtration process (to mirror
the real world process) so instead,
students discuss this in the
analysis section of the lab report.
In reference to assessment, some
checkpoints during the course
of the build, even as formative
assessments would be a way
to keep timelines on track. One
improvement would be to try and
include even more aspects of math
and engineering in the project.
This could be accomplished
by doing a scaled model of the
water filter and even bringing in
some other types of engineering
technology, such as a 3D printer.
Other teachers can use this type
of project to start a unit about
water systems as well, because
the questions and problems
students face are all connected
to the expectations set out by the
ministry. The student example in
the figures below showcase one
group’s exceptional Level 4 effort.
CONCLUSION
The purpose of this project was
to connect a variety of units
studied throughout the course of
the year to create a meaningful
final lab report about water that
was student generated. With this
project, we have done just that,
and have engaged students to
think about water resources and
availability from a citizen scientist
perspective. In the future, I believe
this project will grow to include
printed components of the water
filter from the school’s 3D printers.
This evolution would align with the
underlying goal of this project of
encouraging integration between
the STEM fields.
APPENDIX
Water Filtration Design Project
Grade 8 Science – Water Systems
Big Ideas: Human use of water
resources and water treatment
Background: Water collected from
a source typically goes through
several processes at a water
treatment plant before entering
our homes as potable water. This
design challenge allows you to
investigate the following steps
involved in water treatment and
to suggest some improvements to
your system.
Step 1:
You will be put in groups and you
will need to start a Google Doc
and share that with your group
members and your teacher. This
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FIGURES
Figure 1: Example of student work during the pre lab questions
of the report. This image shows the pulley system created to
bring the water out of the well.
Figure 3: A sample observation table from students.
Microscope pictures are the residue left on the slide after
the filtered water has evaporated.
way your group can effectively create your own lab
report with all the necessary details included. Although
this is a group project, be sure to take note that you
will be marked individually for your efforts. Be sure to
read over the rubric to get an understanding of what is
expected of you.
You will need to include information under the following
headings:
• Purpose
• Hypothesis
•
Materials
Figure 2: The design of the filter as well as the procedure for
putting it together.
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• Design of Pulley
Class 3:
• Design of Filter
1. Begin making observations on at least three trials.
You will need to include an observation table for
this
• Procedure
• Observations
• Results
• Conclusion
Class 1: (approximately 65 minute classes)
1. Complete the pre-lab testing to get an
understanding of what type of water you could be
filtering
2. Make sure you record your results in your lab
3. Answer the pre-lab questions in the Conclusion
part of your lab report
4. Add to your materials design list (assign who will
bring what for the filter)
5. Design your pulley system on paper or using a
computer design software and answer the pulley
questions in conclusion part of lab
2. Set up a slide to have your water sample be
evaporated from. This will allow you to see what
undissolved solids remain
3. Add to your results section of the lab report
Class 4:
1. Finish any of your lab report and ensure you
have your analysis questions answered in your
conclusion section
2. Self and Peer Assessment completed on Google
Form that is formative
The Winner:
The team with the cleanest water after 3 trials
6. Design your filter and have your design approved
by your teacher. Ensure that this design is added
to your lab report
Class 2:
1. Begin construction of your filter, test and make
alterations (you may want photos to support this)
2. Add to your procedure the steps you took to build,
and re-design your filter
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Filtering Dirty Water - Rubric
Group Member’s Names:
Throughout the filtration challenge, you must document the steps your group is taking to build the device. Each
group member will be individually assessed on the following:
Category
Details
Above and
beyond
Level 4
Knowledge
/10
Got it
Level 3
Getting
there
Level 2
Analysis Questions
Pre-lab questions are answered
Fully able to explain analysis questions with supporting detail
Variables are identified in discussion
Design/Observations
Design is clearly labeled and neat (of both pulley and of
water filter)
Describe the testing and redesigning of the system
Improvements are suggested for the overall design
Inquiry
/10
Testing
Follows proper scientific method, fair test, three trials
Students develop model using appropriate materials
Communication List of Materials
Complete, detailed list
/10
Quantities indicated
Written Procedure
Detailed, clearly written steps
Listed numbered steps
Scientific language is appropriate and correctly used
The Results
Results are evaluated with regards to the reliability and
repeatability
Clear and easy to understand results
Application
/10
Total /40
Analysis/Discussion
Filter is evaluated with regard to limitations
Can apply water quality testing to the sample to be filtered
Can apply urban water system filters to model
Understanding of density within own model
Comments:
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2016 VOL 9
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SCIENCE
ARTS
ANDFOR
SCIENCE
THE SOURCE
INTRODUCING THE ARTS AND SCIENCE SECTION
by Cathy Yan and Adela Lam
The Science and arts are commonly considered
to be two vastly different disciplines contrasting
each other primarily in terms of methodology. The
sciences value precision and the ability to control
and replicate results, while arts stem from the fluid
and unique expression of one’s self using different
mediums. However, despite these characteristics,
the ultimate goal of both areas of study is to explore
the unknown. For arts, this entails delving into human
emotions through abstract thoughts and ideas, while
sciences use the same abstractions and imagination
to experiment with and create using objects in the
natural world. This combination of internal and
external explorations define the intrinsic elements of
the universe, which is why arts and science belong
together.
avec et créer des objets du monde naturel. Cette
combinaison d’explorations internes et externes
définit les éléments intrinsèques de l’univers, raison
pour laquelle les arts et sciences appartiennent
ensemble.
In future issues of the journal, the arts and science
section will be showcasing articles that fulfil the
goal of uniting the unexpected by deeply analysing
phenomena demonstrating both scientific and artistic
concepts using multimedia elements such as videos,
diagrams, and sound. In other words, this section
is dedicated to finding the science in arts and vice
versa, illustrating the creative potential of contributors
and revealing connections made between usually
disparate concepts using a variety of different
perspectives. The pieces published will be written by
contributors in high school and university, and will be
curated by the cocoordinators of this section, Adela
Lam and Cathy Yan.
Les pièces publiées seront écrites par des
contributeurs au secondaire et à l’université et sera
sous la tutelle des coordonnateurs de cette section,
Adela Lam et Cathy Yan.
Les sciences et les arts sont souvent considérés
comme deux disciplines vastement différents qui se
contrastent surtout en terme de méthodologie. Les
sciences mettent en valeur la précision et la capacité
de contrôler et répéter des résultats alors que les
arts proviennent de l’expression fluide et unique de
soi-même en utilisant de divers moyens. Cependant,
malgré ces caractéristiques, le but ultime des deux
domaines d’étude est d’explorer l’inconnu.
Pour les arts, ceci implique plonger dans l’émotion
humaine à travers des pensées et des idées
abstraites alors que les sciences utilisent les mêmes
abstractions et la même imagination pour jouer
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Dans des éditions futures du journal, la section des
arts et sciences mettra en vedette des articles qui
atteignent le but d’unir l’inattendu en analysant des
phénomènes démontrant des concepts artistiques
et scientifiques à travers des éléments médiatiques
tels des vidéos, des diagrammes et des sons. Dans
d’autres mots, cette section est dédiée à l’art de
trouver la science dans les arts et vice versa, illustrant
le potentiel créatif des contributeurs et révélant des
connexions entre concepts disparates en utilisant
une variété de différentes perspectives.
THOUGHTS FROM ADELA AND CATHY:
WHAT THIS SECTION MEANS TO US
Cathy - I never realized how narrow my thinking
was before working in this section. With every
interaction I have with everyone on the team, from my
cocoordinator to the ambassadors (who are currently
working on articles that will be published in the next
issue!), Arts and Science become less like an abstract
concept and more tangible. It is embodied by what
are commonly thought to be banal acts that barely
merit attention like the tuning to piano strings to
create certain frequencies of sound waves for music
or camouflage clothing. Essentially, the Arts and
Science section simultaneously breaks down ideas
into disciplinespecific concepts, and squeezes those
same concepts together to generate paradoxical,
deeply explorative pieces. Just like diamonds are
formed by applying pressure to carbon, I hope this
squeezing of concepts will yield something just as
beautiful for you.
Adela - I have always felt as if my life has been
stretched to two poles. As both a student in a math
DOI: 10.13034 / JSST-2016-008
and science program and a
singer representing Canada
internationally, I often feel out
of place in both areas, and I am
sure that there are a multitude
of students, both high school
and university, that share the
same feeling! I’m ecstatic to
work with my cocoordinator
and ambassadors in creating
the novel journal section with a
purpose to show that the topics
of Arts and Science work hand in
hand in a cohesive partnership
where each subject benefits from
each other and how students
can feel passionate about both
without giving up the other. As
Cathy said, we hope to present
existing scientific concepts in a
fresh, new perspective through
the art medium. We’re excited for
you to come along on this journey
with us!
Cathy : je n’ai jamais réalisé
à quel point ma pensée était
étroite avant de travailler pour
cette section. Avec toutes les
interactions que j’ai eues avec les
membres de mon équipe, de ma
partenaire coordonnatrice aux
ambassadeurs, qui travaillent sur
des articles qui seront publiés
dans la prochaine édition, la
section arts et sciences deviendra
moins abstrait et plus tangible.
Il est manifesté par ce qui sont
communément pensés à être des
actes banaux qui ne méritent pas
d’attention, tel l’accord de cordes
de piano à la création de certaines
fréquences d’ondes sonores pour
la musique. Essentiellement, la
section des arts et sciences a
pour but de vulgariser des idées
en concepts spécifiques à la
discipline tout en les utilisant pour
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créer des pièces profondément
exploratifs.
Tout comme des diamants
sont formés en appliquant de
la pression sur le carbone, je
vous souhaite que l’application
de pression sur ces concepts
apportera quelque chose d’aussi
belle que vous.
Adela : J’ai toujours senti que ma
vie a été étendue sur deux pôles.
En tant qu’étudiant dans un
programme de mathématiques
et
sciences
et
chanteuse
représentant le Canada de façon
internationale, je me sens souvent
comme une intruse dans ces deux
régions, et je suis sûre qu’il y a
une multitude d’étudiants, autant
secondaires qu’universitaires, qui
partagent le même sentiment!
J’ai hâte de travailler avec ma
partenaire coordonnatrice pour
créer cette nouvelle section afin
de montrer que les sujets des arts
et des sciences travaillent main
dans la main dans un partenariat
cohésif où chaque matière
bénéficie de l’autre et comment
les étudiants peuvent se sentir
passionnés des deux sans se
renoncer de l’autre.
Comme
Cathy a dit, nous espérons que
nous pourrons vous présenter
des concepts scientifiques à
travers une nouvelle perspective
avec le moyen qu’est les arts.
Nous avons hâte que vous nous
joignez à travers ce saga!!
2016 VOL 9
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INSIGHTS
THE SCIENCE OF TEARS
By Malvika Agarwal
When was the last you cried? Maybe it was while you
were watching a sad movie or when a loved one was
leaving you or because you just felt lonely. The next
thing you know, you have a lump in your throat, your
eyes start to water and tears are running down your
cheeks. Considering that crying is an important and
common part of everyone’s lives, many of us know
surprisingly little about it.
What happens when we cry, exactly? While the
lacrimal gland produces a watery component, the
glands in our eyelids produce an oily component, and
other cells produce mucus. These mix together on
the upper, outer region of your eye to create a film,
which covers the white of the eye and the cornea.
When we blink, the film is wiped across the eye by the
eyelids. This fluid, better known as tears, drains into
the tiny openings in the eyelids, called puncta (one on
the inside corner of each lid), and then through ducts
to the nasal cavity, where they either become part of
nasal fluid or are swallowed. This is why we also get
“stuffy” when we cry. If insufficient tears are produced
or the constituents are out of balance, it can result in
sore, dry eyes.
Over the years, many scientists have researched
on how humans cry. Ad Vingerhoets, a professor
of psychology at Tilburg University, discovered that
there are 3 types of tears. The first type is basal tears,
and they lubricate and protect the eyes at all times
from damage by incoming air currents and floating
debris.
Often, people tend to cry when they are cutting onions.
These types of tears are called reflex tears, which are
produced when the eyes make contact with wind,
sand, insects or rocks. Reflex tears protect the eyes
from irritants such as wind, smoke, and chemicals.
They also help flush out random specks of dirt or any
object that gets into the eye.
The last types of tears are emotional tears, which are
secreted in moments of intense feeling – sometimes
joy, but more often sorrow. These tears ears are
produced in such large quantity that they overflow
and fall down our cheeks. This type of crying occurs
in response to stress, frustration, sadness, and
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happiness, and any other motion that evokes tears.
It has been statistically proven crying is beneficial for
the health of individuals. Studies show that holding
your emotions in can be dangerous over the longterm. In fact, some research indicates that stifling
emotional tears can cause elevated risk of heart
disease and hypertension. Other studies have shown
that people suffering from such conditions as colitis
or ulcers tend to have a less positive attitude about
crying than their healthier counterparts. Psychologists
recommend that people suffering from grief express
their emotions through talking and crying, rather than
keeping their emotions in check. Many studies also
show that women cry 5.3 times a month, while men
only cry about 1.3 times a month on an average.
The reason is that men produce testosterone, which
prevents them to tear up. On the other hand, women
have lots of prolactin (a protein found in the body),
which stimulates tears.
Tears of joy and tears of exhaustion. Tears of a clown
or crocodile tears. Tears caused by chopping onions
and death of a loved one. In the end, a tear is a tear,
and they help protect and preserve the condition of
our eyes. Crying might make your eyes red and puffy,
but they won’t affect your eyesight. So the next time
you have the temptation to cry, go all out!
À quand remonte la dernière fois que vous avez
pleuré? Peut-être que c’était lorsque vous étiez en
train de regarder un film triste ou quand un proche
vous a quitté ou parce que vous vous sentiez seul.
Tout d’un coup, vous avez la gorge serrée, vos yeux
deviennent humides et les larmes commencent à
couler sur vos joues. Comme pleurer joue un rôle
important de la vie de tous, beaucoup d’entre nous
savent étonnamment peu à ce sujet.
Qu’est-ce qui se passe quand nous crions,
exactement? Alors que la glande lacrymale produit
un composant aqueux, les glandes de nos paupières
produisent un composant huileux et d’autres cellules
produisent un mucus. Ceux-ci se mélangent dans
la région supérieure, externe de l’œil et créent une
mince couche qui couvre le blanc de l’œil et la cornée.
Lorsque nous clignons, la couche est distribuée
à travers la surface de l’œil par les paupières. Ce
fluide, c’est-à-dire les larmes, se jette dans les petites
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ouvertures dans les paupières, appelées « punctas »
(une sur le coin intérieur de chaque paupière), puis
à travers des canaux vers la cavité nasale, où soit il
devient partie du liquide nasal soit il est ingéré. Voilà
pourquoi nous devenons aussi congestionnés quand
nous pleurons. Ces larmes coulent ensuite le long
votre visage et ruine votre mascara. Si un montant
insuffisant de larmes est produit ou les constituants
ne sont pas équilibrés, ceci peut causer de la douleur
et la sècheresse des yeux.
que les personnes souffrant de tristesse expriment
leurs émotions en parlant et en pleurant, plutôt qu’en
gardant leurs émotions contenues. De nombreuses
études montrent aussi que les femmes pleurent 5,3
fois par mois, alors que les hommes ne pleurent
que 1,3 fois par mois en moyenne. Ceci est dû à
la testostérone présente chez les hommes, qui les
empêche de pleurer. Par contre, les femmes ont
beaucoup de prolactine (une protéine trouvée dans
le corps), qui stimule les larmes.
Au fil des ans, de nombreux scientifiques ont fait
des recherches intensives, étudiant comment les
humains pleurent. Ad Vingerhoets, professeur de
psychologie à l’Université de Tilburg, a découvert qu’il
existe trois types de larmes. Le premier type est les
larmes de base et leur fonction est de lubrifier et de
protéger les yeux en tout temps. Cela aide à prévenir
les dommages causés par des courants d’air et des
morceaux de débris flottants.
Larmes de joie et larmes d’épuisement. Larmes de
clown et larmes de crocodile. Larmes produites en
coupant des oignons et ceux causées par la mort
d’un être cher. En fin de compte, une larme est une
larme. Qu’elles soient des larmes de base, réflexes
ou émotionnelles, les larmes aident à protéger et à
préserver l’état de nos yeux. Si, les larmes peuvent
rendre vos yeux rouges et gonflés, mais elles
n’affecteront pas votre vue. Donc, la prochaine fois
que vous avez l’envie de pleurer, allez-y, faites-le!
Les gens ont souvent tendance à pleurer en coupant
des oignons. Ce type de larmes s’appelle larmes
réflexes et ces larmes sont produites lorsque les
yeux entrent en contact avec du vent, du sable, des
insectes ou des roches. Les larmes réflexes protègent
les yeux contre des irritants tels que le vent, la fumée
et les produits chimiques. Elles aident également à
éliminer les saletés ou tout autre particule qui peut
pénétrer l’œil.
Le dernier type de larmes est les larmes émotionnelles,
qui sont sécrétées durant les moments de sentiment
intense - parfois la joie, mais plus souvent la tristesse.
Ces larmes sont produites en si grande quantité
qu’elles débordent et tombent sur nos joues. Ce type
de larmes est résulte du stress, de la frustration, de la
tristesse et du bonheur et de toute autre émotion qui
évoque des larmes.
Il est statistiquement évident que pleurer est bénéfique
pour la santé des individus. Certaines études
démontrent que la suppression des émotions peut
être dangereuse à long terme. En fait, des recherches
indiquent qu’éviter les larmes émotionnelles peut
causer un risque élevé de maladie cardiaque et
d’hypertension. D’autres études ont démontré que les
personnes souffrant de maladies telles que la colite
ou d’ulcères ont tendance à avoir une attitude moins
positive au sujet de pleurer que leurs homologues
en bonne santé. Les psychologues recommandent
DOI: 10.13034 / JSST-2016-010
REFERENCES
1. Duffin. C. Why do we Cry Tears of Joy?. TMG
[Online] 2014, 4.3,22-25.
2. Mikulak, A; Aragon, O; “Tears of Joy” May Help
Us Maintain Emotional Balance. PSA. [Online]
2014, 2.1, 30-35.
3. Oaklander. M. The Science of Crying. TSA
[Online] 2016, Version 4.2, 3-10.
4. Oskar, S. Why do we cry?. CPJ [Online]. 2013,
Version 1. 60-69
5. Popova, M. The Science of Why We Cry and the
Three Types of Tears. [Online] 2012,107, 4-5.
PROTON THERAPY – A
NEW TOOL FOR TREATING
CANCER
By Lawrence Pang
One of the most effective ways of combating cancer
is radiation therapy. Traditionally, radiation therapy
uses photons in the form of high-energy x-ray
radiation, which ionizes (i.e. removes or adds an
electron) atoms in the DNA chains of cancerous cells.
2016 VOL 9
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This changes the chemical properties of the atom,
damaging the DNA and preventing the cancerous cell
from multiplying.
One significant issue with radiotherapy is that regular
cells in the vicinity of cancerous cells are also
impacted by the radiation. Photons are not charged so
they are not attracted or repulsed by any atoms. They
can only interact with matter via absorption. Whether
absorption actually occurs is purely reliant on chance.
Given a certain amount of tissue, the proportion of
photons that are absorbed by the tissue at each
depth is constant, so the total photon dose delivered
to the tissue increases slowly. This is demonstrated
in the Bragg curve, which indicates the energy loss
of various types of radiation as they travel through
matter. As can be seen in the graph below, the Bragg
curve of the photon beam (pink) decreases slowly
as only relatively few photons lose their energy (i.e.
are absorbed) at each depth. Furthermore, photons
are also sometimes re-emitted by atoms at different
angles, so some of the dose will also be scattered
into surrounding tissue. Therefore, many healthy
cells outside of the tumour will also be affected.
dose is delivered to the specific peak area, and
almost none to surrounding regions. The location
of this peak can be controlled by radiating protons
of different energies. Furthermore, because protons
are also relatively massive, there is a negligible
scattering effect. Therefore, only cancerous cells can
be targeted, and no damage is done to the DNA of
surrounding healthy cells.
Proton therapy, while exciting, has its own unique
disadvantages. The large mass of protons is beneficial
when it comes to reducing scatter but is a barrier when
it comes to delivering cost-effective therapy. Protons
must be accelerated to very high speeds as part of
the therapy, which requires expensive equipment in
the form of cyclotrons or synchrotrons (i.e. particle
accelerators). Few proton therapy centers have been
established due to the discouraging capital cost.
There is only one in Canada: the TRIUMF center
in Vancouver. In addition, the relative cost of proton
therapy is more than twice that of photon therapy
(Goitein and Jermann, 2003). However, more modern
proton beams can reduce the cost dramatically, and
as a result the cost of proton therapy is no longer
unrealistic for patients (Lievens and Van den Bogaert,
2005).
Ultimately, proton therapy is a solid prospective
technology, especially for tumours in sensitive
regions such as the eyes. The jury is still out on its
effectiveness in general; the consensus seems to
be that proton therapy has significant theoretical
advantages but not clinical benefits (St. Clair et al,
2004). Currently, a five-year study of proton therapy’s
effectiveness against prostate cancer is underway at
Massachussetts General Hospital. We hope that its
results will lead to yet another powerful weapon in the
fight against cancer.
Source: Miller, A. Bragg Peak. https://commons.
wikimedia.org/wiki/File:BraggPeak.png
(accessed
March 23, 2016). Copyright 2005 by A. Miller.
Reprinted with permission.
This side effect can be resolved with proton therapy,
which is simply radiating protons and not photons.
As can be seen in the graph on the left, the proton
beam (blue and red) has a sharp peak in the Bragg
curve. This indicates that a vast majority of the proton
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Une des façons les plus efficaces de combattre
le cancer est la radiothérapie. Traditionnellement,
la radiothérapie utilise des photons en forme de
rayonnement ionisant à haute énergie, ce qui ionise
(c.-à-d., retire ou ajoute un électron) les atomes dans
la chaîne ADN des cellules cancéreuses. Ceci change
les propriétés chimiques de l’atome, endommageant
l’ADN et empêchant la multiplication des cellules
cancéreuses.
Un enjeu important en ce qui concerne la radiothérapie
est que les cellules normales à proximité des
DOI: 10.13034 / JSST-2016-010
cellules cancéreuses sont également affectées
par la radiation. Les photons ne possèdent pas de
chargent donc ils ne sont pas attirés ou repoussés
par aucun atome. Ils ont seulement la capacité
d’interagir avec la matière par absorption. Que
l’absorption se produit réellement dépend purement
du hasard. Étant donné une certaine quantité de
tissu, la proportion de photons absorbés par les
tissus à chaque profondeur demeure constante,
ainsi la dose totale de photons délivrés aux tissus
augmente lentement. Ceci est démontré dans la
courbe de Bragg, qui indique la perte d’énergie d’une
variété de types de radiation lors du déplacement à
travers la matière. Comme le montre le graphique cidessous, la courbe de Bragg du faisceau de photons
(rose) diminue lentement puisque seulement une
quantité relativement minime de photons perdent leur
énergie (c.-à-d., sont absorbés) à chaque profondeur.
Par ailleurs, les photons sont aussi parfois réémis
par les atomes à différents angles, donc une partie
de la dose sera également propagée dans le tissu à
proximité. Ainsi, de nombreuses cellules saines se
trouvant à l’extérieure de la tumeur seront également
affectées.
Cet effet secondaire peut être résolu avec
la protonthérapie, qui est tout simplement le
rayonnement de protons et non photons. Comme
le démontre le graphique à la gauche, le faisceau
de protons (bleu et rouge) possède un sommet à pic
dans la courbe de Bragg.
Ceci indique qu’une grande majorité de la dose de
protons est délivrée à la région spécifique indiquée
par le sommet à pic, et presqu’aucune dans les
régions environnantes. L’emplacement de ce
sommet peut être contrôlé en émettant des protons
d’énergies différentes. En outre, puisque les protons
sont relativement massifs, l’effet de dispersion est
négligeable. Par conséquent, seules les cellules
cancéreuses sont ciblées et l’ADN des cellules
saines environnantes n’est pas endommagé. La
protonthérapie, tout en étant excitante, possède des
inconvénients particuliers. La grande masse des
protons est bénéfique en ce qui concerne la réduction
de l’effet de propagation, mais se porte un obstacle
lorsqu’il s’agit d’offrir un traitement économique.
Les protons doivent être accélérés à des vitesses
très élevées pour cette thérapie ce qui nécessite
de l’équipement coûteux, soit des cyclotrons et
DOI: 10.13034 / JSST-2016-010
synchrotrons (c.-à-d., accélérateurs de particules).
Peu de centres de protonthérapie ont été mis en
place en raison de coûts en capital décourageant. Il y
en a seulement un au Canada : le centre TRIUMF à
Vancouver. De plus, le cout relatif de protonthérapie
est plus de deux fois celui de la thérapie photonique
(Goeitein et Jermann, 2003).
Cependant, les
faisceaux de protons plus modernes peuvent réduire
considérablement le coût, et par conséquent le coût
de la protonthérapie n’est plus irréaliste pour les
patients (Lievens et Van den Bogaert, 2005).
Tout compte fait, la protonthérapie est une
technologie prospective assurée, en particulier
pour des tumeurs dans des régions délicates telles
que les yeux. Des incertitudes reposent encore
en ce qui concerne sont efficacité en générale; le
consensus semble indiquer que la protonthérapie
présente des avantages théoriques importants,
mais non des avantages cliniques (St Clair et al,
2004). Couramment, une étude de cinq ans portant
sur l’efficacité de la protonthérapie contre le cancer
de la prostate est en cours à l’Hôpital Général de
Massachusetts. Nous espérons que ses résultats
conduiront à une autre arme puissante dans la lutte
contre le cancer.
REFERENCES
1. Greco, C.; Wolden, S. Current status of
radiotherapy with proton and light ion beams.
Cancer. 2007, 109, 1227-38.
2. Goitein, M.; Jermann, M. The Relative Costs
of Proton and X-ray Radiation Therapy. Clinical
Oncology. 2003, 15, 37-50.
3. Lievens, Y.; Van den Bogaert, W. Proton
beam therapy: Too expensive to become true?
Radiotherapy and Oncology. 2005, 75, 131-3.
4. St. Clair, W. H. Advantage of protons compared
to conventional X-ray or IMRT in the treatment
of a pediatric patient with medulloblastoma.
International Journal of Radiation, Oncology,
Biology, Physics. 2004, 58, 727-34.
5. Terasawa, T.; Dvorak, T.; Ip, S. Systematic
Review: Charged-Particle Radiation Therapy for
Cancer. Annals of Internal Medicine. 2009, 151,
556-65.
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HEAT VISION: SUPERMAN
OR PIT-BEARING SNAKES?
By Jason Baek
When one reads the words ”heat vision,” it is common
to imagine Superman flying through the air, blasting
red beams from his eye sockets. Although this is a
fairly creative image, the type of “heat vision” found
in many snakes is different. When alluding to “heat
vision” in snakes, one refers to the ability of certain
snake species to sense heat through pit organs. These
structures connect with a snake’s sense of touch,
with the trigeminal nerves and ganglia being major
components of this mechanism. Transient receptor
potential cation channel, member A1, or PRTA1, is a
protein found in the stems of trigeminal nerves. It is
often asserted that the evolution of PRTA1 is directly
connected to the evolution of infrared sensory pitbearing snakes.
It has been proposed that the evolution of PRTA1
was central to the evolution of infrared sensory in pitbearing snakes. In a study conducted on pitvipers,
PRTA1 gene expression in trigeminal nerves was
found to be higher than in dorsal root glands. This
differs from the results in non pit-bearing snakes,
where PRTA1 expressions were similar in both
locations. These trigeminal nerve areas were initially
predicted for high PRTA1 expression because the
ganglia— structures to which trigeminal nerves attach
to— are larger in pitvipers than in other vertebrae.
Trigeminal nerves are also closest in proximity to pit
organs relative to other parts of the somatosensory
system such as dorsal root glands, which interact
with the trunk of vipers. It is both the higher gene
expression of PRTA1 as well as the relative proximity
of trigeminal glands to the pit organ, which suggest
that PRTA1 is important to the functioning of pit
organs.
Although evidence suggests that PRTA1 is important
to pit organ function, one cannot necessarily assume
that this channel has a function integral to heat
sensing. Relevance of PRTA1 in pit-bearing snakes,
specifically as a heat-sensitive protein, needed to be
tested. To test this, PRTA1 proteins were exposed to
different temperatures to observe the effect of heat
on activity. Relative to PRTA1 in pit-bearing snakes,
the proteins in non pit-bearing snakes needed to
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be subject to higher temperatures in order to yield
equivalent results. Proteins in pit-bearing snakes
showed higher levels of activity starting from lower
temperatures, indicating greater sensitivity to heat.
It was only through meticulous work that Yale
University’s Elena Gracheva and her colleagues
were able to reveal the importance of PRTA1 as a
heat-sensitive protein in pit-bearing snakes, with their
study being published in 2010.
But what could have driven the evolution of a more
heat-sensitive PRTA1 in pit-bearing snakes? Jie Geng
and his colleagues at the Sun Yat-Sen University in
Guangzhou, China, have revealed positive selection
as a proposed mechanism by which evolution of
PRTA1 occurred. Positive selection otherwise known
as Darwinian selection is the process of an allele
being fixated within population overtime due to it
increasing the organism’s chance of passing on its
genes. Using computers, cDNA sequences for PRTA1
and a related/orthologous protein were generated.
Complementary DNA or cDNA strands are copies
of DNA synthesized from messenger RNA. The
related protein was necessary for comparison, as
assessing any differences between the two proteins
of similar origin would give clues as to how they
evolved differently from each other. After the analysis
of phylogenetic trees, it was determined that PRTA1
evolution in pit-bearing snakes was indeed very likely
to have been driven by positive selection.
With positive selection being the likely mechanism,
it is often assumed that snake populations evolved
a heat-sensitive pit organ simply for prey acquisition.
According to Aaron Krochmal and a team of
researchers from the Indiana State University, this
is not entirely correct and pit organs serve multiple
functions. To test this, pit-bearing and non pit-bearing
vipers were made to navigate a maze and exposed
to sub-lethal temperatures to motivate them to seek
thermal refuge. All pit vipers reached the thermal
refuge however; non pit-bearing vipers were unable
to. Therefore, more active thermoregulatory behavior
in pitvipers as a result of better infrared sensitivity
is a possible reason for positive selection of pit
organs. Vipers that were better able to regulate their
body temperature and avoid lethal environmental
conditions had a higher chance of passing on their
genes. Modern pitvipers often do use infrared sensory
to aid in prey acquisition; however, archaic pit organs
DOI: 10.13034 / JSST-2016-011
were insensitive to heat and unable to distinguish
between heat signatures of prey and the ambient
environment. Thus, thermoregulatory behavior is
the probable cause pitvipers evolved to have more
sensitive facial pits.
The three studies conducted show how the alteration
in the genes of a specific protein at a molecular level
could lead to the evolution of a species. To conclude,
heat vision is an imaginative superpower in the
context of science fiction but a product of millions of
years of evolution in pit-bearing snakes.
Quand une personne lit les mots ”vision de chaleur,”
il est naturel que la première chose qui vient a tête est
l’image de Superman qui vole dans le ciel avec des
rayons rouges quit sortes de ses yeux. Bien que ceci
est une image créative, le type de “vision de chaleur”
qui se trouve dans les serpents est très différent.
Lorsqu’on parle de “vision de chaleur” dans les
serpents souvent on réfère à l’abilité que l’èspece de
serpent peut sentir la chaleur à travers de ses organes.
Ces structures on des connections avec le sens du
toucher d’un serpent, avec les nerves trijumeau et
le ganglion qui sont des composants major de cette
méchanism. Le canal cationique potentiel de récepteur
transitoire, membre A1, ou PRTA1, est un protéin
qui se trouve dans les tuyaux des nerves trijumeau.
Il est souvent affirmé que l’évolution du PRTA1 est
directement connecté à l’évolution des serpents de
puits avec sensorielle infrarouge.
Il a été proposé que l’évolution de PRTA1 est centrale
à l’évolution des serpents de puits. Dans une étude
mené sur les vipères de puits, l’expression du gène
PRTA1 dans les nerfs trigéminales a été trouvé
d’étre en plus que ceux dans les ganglions de racine
dorsales. Ceci est différent des résultats des serpents
non-puits, ou l’expression du PRTA1 était similaire
dans les deux lieux. Ces zones nerveuses trigéminales
ont été prédites initialement pour une expression
élevée de PRTA1 parce que les ganglions de racine
dorsale auxquels les nerfs trigéminaux s’attachaient
sont plus larges dans les vipères de puits que dans
les autres vertébrés. Les nerfs trigéminaux sont les
plus proches d’organes reliées à d’autres parties
du système somatosensoriel telles les ganglions
dorsales, qui intéragissent avec le tronc des vipères.
L’expression élevée de PRTA1 et la proximité des
DOI: 10.13034 / JSST-2016-011
glandes trigéminales suggèrent que PRTA1 est
important pour la function des serpents de fossettes.
Bien qu’il a été suggéré que PRTA1 est important
à la fonction des organes des serpents, on ne peut
pas assumer que ce canal a une fonction intégrale
à la perception de la chaleur. La pertinence de
PRTA1 dans les serpents à fossettes, spécifiquement
comme protéine sensible à la chaleur, devait être
évaluée. Pour verifier cela, les protéines PRTA1 ont
été exposées à des températures différentes afin
d’observer l’effet de la chaleur sur leur activité. En
relation à PRTA1 dans les serpents de fossettes, les
protéines d’autres serpents devaient être exposées
à des températures plus élevées afin d’obtenir des
résultats équivalents. Les protéines dans les serpents
à fossettes montraient de l’activité à des niveaux plus
élevés afin d’obtenir des résultats équivalents. Les
protéines dans des serpents à fossettes montraient
des niveaux d’activité nettement plus élevés à partir
de températures plus basses, montrant qu’ils sont
plus sensibles à la chaleur. C’est à travers le travail
méticuleux d’Elena Gracheva, de l’université Yale,
et ses collègues, qui révélé l’importance de PRTA1
comme protéine sensible à la chaleur chez les
serpents à fossettes, et leur étude a été publiée en
2010.
Mais qu’est-ce qui aurait pu entraîner l’évolution d’une
PRTA1 plus sensible à la chaleur dans les serpents
avec des fossettes sensorielles? Jie Geng et ses
collègues à l’Université Sun Yat-Sen à Guangzhou,
en Chine, ont révélé la sélection positive comme
mécanisme proposé par lequel l’évolution de la PRTA1
a eu lieu. La sélection positive, autrement connue sous
le nom de sélection darwinienne, est le processus où
un allèle est fixé dans une population avec le temps
parce qu’il augmente la probabilité que l’organisme
transmettra ses gènes. En utilisant des ordinateurs,
les séquences d’ADNc pour la PRTA1 et une protéine
apparentée/orthologue étaient générées. Les brins
d’ADN complémentaire, ou ADNc, sont des copies
d’ADN synthétisées par l’ARN messager. La protéine
apparentée était nécessaire pour la comparaison,
puisque l’évaluation des différences entre les deux
protéines d’origine similaire donnerait des indices à
la façon dont elles ont évolué différemment l’une de
l’autre. Après l’analyse des arbres phylogénétiques,
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il fût déterminé qu’il était très probable que l’évolution
de la PRTA1 dans les serpents avec des fossettes
sensorielles a été entraînée par la sélection positive.
L’évolution sélective étant le mécanisme le plus
probable, il est souvent supposé que les populations
des serpents ont évolué des fossettes simplement
pour l’acquisition des proies. Selon Aaron Krochmal
et une équipe de chercheurs de l’Université d’État
d’Indiana, ceci n’est pas tout à fait correcte et les
fossettes sensorielles remplissent plusieurs fonctions.
Pour tester ceci, des serpents avec des fossettes
et des serpents sans fossettes furent apportés à se
naviguer dans un labyrinthe dans des températures
sublétales pour les motiver à chercher un refuge
thermique. Toutes les vipères à fossettes atteignirent le
refuge thermique; toutefois, les vipères sans fossettes
furent incapables. Donc, le comportement plus
activement thermorégulateur des vipères à fossettes
comme résultat d’une meilleure sensibilité infrarouge
est une raison possible pour la sélection positive des
fossettes. Les vipères qui étaient mieux à réglementer
leur température corporelle et éviter des conditions
environnementales létales avaient une meilleure
chance à transmettre leurs gènes. Les vipères à
fossettes actuelles utilisent souvent la détection
infrarouge pour assister à l’acquisition des proies;
toutefois, les fossettes archaïques étaient insensibles
à la chaleur et incapables de distinguer entre les
signatures thermiques des proies et l’environnement
ambient. Donc, le comportement thermorégulateur est
la cause probable pour laquelle les vipères à fossettes
ont évolué pour avoir plus de fossettes au visage.
Ces trois études réalisées indiquent montrent comment
l’altération des gènes d’une protéine spécifique à un
niveau moléculaire pourrait mener à l’évolution d’une
espèce. Pour conclure, la vision thermique est une
superpuissance dans le contexte de la science-fiction
mais elle est le produit de millions d’années d’évolution
dans les serpents avec des fossettes sensorielles.
REFERENCES
1. Geng, J., Liang, D., Jiang, K., Zhang, P.
Molecular evolution of the infrared sensory gene
PRTA1 in snakes and implications for functional
studies. PloS One 2011, 6, e28644. 10.1371/
journal.pone.0028644
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2. Gracheva, EO., Ingolia, NT., Kelly, YM.,
Coredero-Morales, JF., et al. Molecular basis of
infrared detection by snakes. Nature 2010, 464,
1006–1011. 10.1038/nature08943
3. Krochmal, AR., Bakken, GS., LaDuc, TJ., Heat
in evolution’s kitchen: evolutionary perspectives
on the functions and origin of the facial pit of
pitvipers (Viperidae: Crotalinae). J Exp Biol. 2004,
207, 4231–4238. 10.1242/jeb.01278
ME, MYSELF, AND THE
UNIVERSE
By Kelvin Zhang
When you look up in the night sky, you see stars.
Hundreds, thousands of them, glimmering and
glistening, each and every one bigger and brighter
than our own sun.
A hundred billion stars lie in our galaxy,
and another hundred billion galaxies in our universe.
Our minds are unable to comprehend how large the
universe really is.
From that perspective, the Earth is tiny.
But everything you have ever known, everyone you
have ever loved
lies on that small dot orbiting the sun.
Everyone that has ever lived.
Every human, every organism.
Every great leader.
Every saint and sinner.
On that small blue planet.
To think of the blood that we shed,
of all the destruction that we caused
just to be temporary leaders of a small place —
It makes you feel small. Insignificant.
Our lives may be a small fraction of the universe,
but you should feel big,
because the Universe is in you.
You are those very atoms that the Big Bang created,
those very atoms scattered by the deaths of stars.
Those atoms, the pieces to a puzzle,
that continuously rearrange themselves forming intricate patterns.
DOI: 10.13034 / JSST-2016-012
Growing in size and complexity
and over billions of years:
You are here.
You are connected to the universe.
Atoms with consciousness.
Matter with curiosity.
You,
a universe of atoms —
an atom in the universe.
That is the beauty of science, the universe, and you.
Quand vous regardez dans le ciel pendant la nuit,
vous voyez des étoiles.
Des centaines, des milliers d’entre eux, étincelantes
et luisantes,
chacun plus grand et plus lumineux que notre soleil.
Un dix milliards d’étoiles se trouvent dans notre
galaxie,
et une autre dix milliards galaxies dans notre univers.
Nos esprits sont incapables de comprendre la taille
réale de l’univers.
De ce point de vue, la Terre est minuscule.
Mais tout ce que vous avez connu, tout le monde
vous avez aimé
se trouve sur ce petit point en orbitant autour du soleil.
Tout le monde qui ait vécu.
Chaque homme, chaque organisme.
Chaque grand dirigeant.
Chaque saint et le pécheur.
Sur cette petite planète bleue.
De penser à propos le sang que nous avons versé,
de toutes les destructions que nous avons causées
Seulement pour devenir un dirigeant temporaire
d’une petite place Il vous fait sentir petit. Insignifiant.
Nos vies peuvent être une petite fraction de l’univers,
mais vous devriez vous sentir grand,
parce que l’Univers fait d’une partie de vous.
Vous êtes les atomes que le Big Bang a créé,
ces atomes très dispersés par la mort des étoiles.
Ces atomes, les pièces à un puzzle,
qui se réorganise en permanence formant des motifs complexes.
En croissant dans la taille et de la complexité
et des milliards d’années:
Vous êtes ici.
Vous êtes connecté à l’univers.
Les atomes avec la conscience.
La matière avec le curiosité.
Vous,
un univers d’atomes un atome dans l’univers.
C’est la beauté de la science, l’univers, et vous.
On the Cover
Justin Parreno is currently a postdoctoral researcher at the Lunenfeld-Tanenbaum Research Institute in
Toronto. Formerly, he completed his Masters of Science in Medical Science with a specialization in Bone and
Joint Health at the University of Calgary’s McCaig Bone and Joint Institute. Additionally, he completed his
PhD at the University of Toronto, where he studied Bioengineering of Articular Cartilage. Justin’s research
focuses on investigating the role of the cytoskeleton in regulating musculoskeletal cell phenotype. He has
received several accolades and has been invited to give talks at national and international-wide institutions
for his research. Aside from his research, Justin is involved in promoting science to youth through Scholarship
initiatives.
Justin Parreno
DOI: 10.13034 / JSST-2016-012
The cover image depicts cartilage cells or chondrocytes as would be utilized clinically for cartilage repair
therapies. Depicted in blue is the chondrocyte nucleus, while green is the actin cytoskeleton. The actin
cytoskeleton regulates cartilage matrix deposition which is necessary for cell-based repair. This issue’s
cover image captures more than what Justin saw under the microscope; it captures the exciting discoveries
that science has to offer. Through our Journal, The Foundation of Student Science & Technology would like
to showcase the hard work of researchers like Justin, to inspire students to become emerging leaders in
science, hence our motto “Connecting, Investing, and Building Our Future”.
2016 VOL 9
ISSUE 1
61
Excerpts from the Chairman’s Letter: March 2016
Edition
2016-03-08
Peter D’Amico
Jacques Guerette
Dr. Brad Bass
Steve Sharp
Peter D’Amico has stepped down as Executive Director but we are not losing his valuable
perspective. Instead, he is re-joining our Board to continue to shape the organization and he will lead
an expanded initiative. The Foundation of Student Science & Technology and the Board would like to
thank Peter for his contributions in working to get the Foundation this far and readying us for growth.
We are very pleased that Jacques Guerette has agreed to serve as Executive Director. Jacques
is a senior executive who has worked for many years to promote and advance the science and
technology ecosystem, a rich network consisting of industry, academia, government and others. He
has been serving on our Board and has stepped down from it to fulfill this management role.
We are equally pleased that Dr. Brad Bass has agreed to serve in a newly created role, that of
Associate Executive Director. Dr. Bass is an Adjunct Professor at the University of Toronto in the
School of the Environment and the founder and Director of the University Research Experience in
Complex Systems (URECS). Brad has been involved in our Ambassador Program, something that he
will continue to lead.
Steve Sharp is joining the Foundation as our Treasurer and will also be part of our Board. Steve is a
chartered accountant and he has been working with us informally for some time to consolidate and
manage our financial affairs.
Each of these appointments will focus on specific priorities for 2016 that collectively will help us fulfill
our raison d’etre which is to cultivate tomorrow’s science leaders by advancing their early knowledge
of career demands and challenges.
Website Partnership Announcement FSST-SMP
2016-02-06
We are excited to announce a new partnership between The Foundation for Student Science and
Technology (FSST) and the Summer Mentorship Program (SMP), run by the Faculty of Medicine at
the University of Toronto.
SMP allows high school students of Indigenous and African ancestry, who are underrepresented
in medicine, to earn course credit over the summer while exploring the health sciences through
experiments, lectures, and special projects.
The Foundation will invite all SMP students to submit their work for publication in the Journal of
Student Science and Technology (JSST). Two SMP students published in the September 2015 issue
of JSST. Ayesha Hassan, 17, describes publishing an article in JSST as the “greatest achievement of
[her] high school career,” while Petra Famiyeh, 18, felt that her “sleepless nights reading and revising
had paid off.”
Ayesha Hassan
Petra Famiyeh
Ike Okafor, program director of SMP, values how this new partnership will develop the career potential
of his students.
“This is a highly valued partnership which will provide students from our summer mentorship program
with invaluable opportunities of conducting research under the guidance of leading Canadian
researchers.”
Other SMP students will be publishing in the upcoming issue of JSST and participating in our
provincial Student Science and Technology Online Research Co-op Program. We are proud of the
success of Ayesha and Petra and optimistic about the potential for this program to strengthen the
programs of both FSST and SMP.
HHS Research
Advancing health care
in our community
and around the world
www.hhsresearchadmin.ca
The Journal of Student Science and Technology and our other programs are made possible by the support of our donors and
partners. Please consider becoming one and help us find and develop the next generation of innovators.
VISIONARIES
PREVIOUS SPONSORS
Ontario Ministry of Education
SUPPORTERS
Aventis BioTalent Challenge (Sanofi-Pasteur)
Canadian Science Publishing
CISCO Academy Canada
Enbridge
Information and Communication
Technology Council
Youth Science Canada
Canadian Space Agency
Western University
University of Ontario Institute of Technology
Dr. Robert Bondar (First Canadian Female Astronaut)
Dr. Leonard Nurse and David Dolley (Nobel Laureates)
Toronto City Council
Hon. Ken Dryden, MP
Hon. Lorenzo Berardinetti, MPP
Ryerson University
Let’s Talk Science
PARTNERS
MOTIVATORS
Amgen
Google
Natural Resources Canada/Resources naturelles Canada
The McLean Foundation
PERSUADERS
Bayer
Canadian Psychological Association/
Sociétè Canadienne de psychologie
TD Canada Trust
FRIENDS
Alexander Cui
Amy Chen
Arri Ye
Brian Nei
Centre for Drug Development and Research (CDRD)
Daniel Kwon
Daniel Liu
Eniko Zsoldos
Fiona Murray
Gerardo Luyando-Lopez
Hadiqa Rahman
Hafsaah Mirza
Hugh McCauly
James Nicolas
Jiamin Li
Jian Wu Ding
Jody Mou
Liza Chong
Malathy Kumaravadivel
Megan Li
Mei Yi Niu
Nehal Thakar
Papiha Joharapurkar
Rajesh Ray
Richard Ren
Rushay Naik
Saisujani Rasiah
Sandy Dai
Sawmmiya Kirupahara
Sharlene Goncalves
Sharon Low
Sherry Liu
Terry Chen
Umesh SHroff
Utkarsh Kanabar
Vipul Shah
Van Trinh
Winko Chan
Yan Feng
Yem Chin Lin
Ontario Ministry of Education
Science Expo
Hamilton Health Sciences
Deep River Science Academy (DRSA)
Sanofi Biogenius Canada
Youth Sciences Canada/Science jeunesse Canada
COMMUNITY SUPPORTERS
Volunteer Bénévoles Canada
Youth Scope
Public Knowledge Project (PKP)
ACADEMIC PARTNERS
Ryerson University
University of Toronto
McMaster University
Laurentian University/Université Laurentienne
Northern Ontario School of Medicine
STUDENT ORGANIZATION PARTNERS
UWO Scientific Research Society
Ontario Science Students’ Association (OSSA)
How to contact us:
Foundation for Student Science and Technology
141 Laurier Avenue West, Suite 702
Ottawa, Ontario K1P 5J3
Email:
[email protected]
Subissions of Journal Articles:
[email protected]
www.fsst.ca
Online Donations:
www.canadahelps.org/en/charities/foundation-for-student-science-technology/
HOW CAN YOU
CHANGE THE WORLD?
The SBC competition provides unique
research opportunities to young Canadians.
It allows you to design and propose your own
biotechnology research project and work
with real scientists in real labs!
The SBC competition gives you the chance to
win cash prizes, scholarships, and more!
Don’t wait! Apply today!
Get more details at
www.biogenius.ca
@biogeniusCA
Sanofi Biogenius
TITLE SPONSORS
PARTNERS IN RESEARCH CANADA | Managing Partner of the SBC National Competition | www.pirweb.org
Ontario On-Line Research Co-op
for high school students
Recherche COOP en ligne de l’Ontario
pour étudiants de niveau secondaire
The Online Research Co-op experiential education
program has been collaboratively developed by The
Journal of Student Science and Technology and the
federal Science and Technology Cluster (Science.gc.ca)
to help students transition from secondary school into
postsecondary education and introduce them to
knowledge-based professions.
Le programme COOP de recherche en ligne été élaboré
conjointement par La revue pour les étudiants en
technologie et sciences et le Regroupement des sciences et
de la technologie (Science.gc.ca) pour aider les étudiants à
passer de l’école secondaire aux études postsecondaires et
pour les initier aux professions basées sur la connaissance.
The program matches highly motivated high school
students, in grades 11 and 12, with top researchers in
the fields of science and technology. Students are
offered opportunities to work on research projects, to
be immersed into professional online communication
and work environments, and to gain early exposure to
careers in science and technology. The online format
of the learning makes it accessible to all students,
including those who require more flexible schedules,
and those living in remote areas.
Ontario high schools can now apply to offer this
opportunity for their students.
If you are a student or teacher who would like to take
part, please contact [email protected]
Le programme COOP de recherche en ligne vise à jumeler
des élèves très motivés de niveau secondaire, de la 11e et
12e année, avec des chercheurs émérites du domaine des
sciences et de la technologie. Les élèves ont la possibilité de
travailler à des projets de recherche, d’être immergé dans un
environnement virtuel de travaille et de communication
professionnel, et d’être exposés tôt à des carrières en
sciences et en technologie. La formule en ligne de
l’apprentissage rend cette expérience accessible à tous les
étudiants, y compris ceux qui ont besoin des horaires plus
souples et ceux qui habitent dans des régions plus isolés.
Les écoles secondaires ontariennes peuvent actuellement
présenter une demande afin d’offrir cette occasion aux
étudiants.
Si vous êtes un(e) élève ou un(e) enseignant(e) et que vous
désirez participer à ce projet, veuillez communiquer avec
[email protected]
If you are a scientist and would like to participate in
this project, please contact [email protected].
Si vous êtes un(e) scientifique et que vous désirez participer
à ce projet, veuillez communiquer avec
[email protected].
For more information visit science.gc.ca/course
Pour plus d’informations s’il vous plaît visitez
science.gc.ca/cours
141 Laurier Avenue West, Suite 702
Ottawa, Ontario
K1P 5J3

Building On Science: My Career (So Far) In Cell Research p. 46

Transcription

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