VictorJuiz/thesis huggingface dataset:
Characterizing the Role of RhoGAP19D in Drosophila Epithelial Development

The establishment and maintenance of epithelial polarity is dependent on polarity regulators. One such polarity regulatory is Bazooka (Baz). Baz is located around the apical circumference, serving as a cytosplasmic scaffold to assemble adherens junctions. In vitro analyses presented RhoGAP19D as a potential Baz-interacting protein. RhoGAP19D’s homologs have been linked to the actin cytoskeleton and the PAR complex through the RhoGTPase CDC42. To study RhoGAP19D’s functions, a GFP-tagged RhoGAP19D was made. This construct was expressed in the Drosophila embryonic ectoderm and follicular epithelium. It localized to the apical circumference with enrichment at Baz-puncta and actin-rich locations, but its main localization mechanism appears to be independent of Baz. Gain-of-function and loss-of-function analyses for RhoGAP19D revealed phenotypes consistent with it being an inhibitor of the PAR complex and the actin cytoskeleton. Thus, I hypothesize that RhoGAP19D regulates Drosophila epithelial polarity by inhibiting the PAR complex and the actin cytoskeleton by inhibiting CDC42.

Keywords: Cell Polarity
Development
Drosophila
Advisor: Harris, Tony
The Role of Attachment Avoidance in Social Comparisons between Romantic Partners

Recent literature suggests that individuals respond more positively when outperformed by their partner (an upward comparison) than when they outperform the partner (a downward comparison). In some cases, however, individuals may respond negatively to a superior partner. In two studies, I examined attachment avoidance as a moderator of social comparison outcomes: I predicted that avoidant individuals would respond more negatively to upward than downward comparisons by distancing themselves from the partner (reducing closeness) and disengaging from the relationship (reducing commitment). In Study 1, attachment avoidance moderated comparison direction’s impact on closeness: Avoidant participants reported less closeness, especially after encountering a superior partner. Study 2 replicated Study 1’s findings and found that avoidant individuals reported less commitment after an upward comparison, but only in the organizational domain. Thus, not all individuals respond positively to upward comparisons with their partner; for avoidant individuals, upward comparisons may be harmful to their relationship.

Keywords: romantic relationships
social comparisons
Advisor: Lockwood, Penelope
The Effect of Enhancing Prototype Salience on the Accuracy of Categorizing Sexual Orientation from Faces

Recent literature in person perception suggests that sexual orientation and other perceptually-ambiguous group memberships could be discerned from faces with accuracy exceeding chance levels. No study to date has explored the question of how people acquire mental representations of sexual orientation, however. In Study 1, I show that the perception of sexual orientation is distinct from that of obvious group memberships. Then, I show that people can learn prototypical representations of sexual orientation to increase their sensitivity to artificially-generated stimuli (Study 2) and to actual faces (Study 3). Last, I demonstrate that this improvement is a product of participants’ attunement to the patterns of facial features in the prototypes of the two categories. Together, the results demonstrate that people can learn mental representations of sexual orientation through exposure to environmentally relevant stimuli. Furthermore, the studies provide insights about how the mind learns social categories more generally.

Keywords: person perception
sexual orientation
Advisor: Rule, Nicholas O.
Fecal Microbial Composition in Relation to Diet and Body Mass Index

Emerging evidence from animal and human studies has indicated a potential link between a certain pattern of gut microbiota and adiposity. In the current study, the relationship between gut microbial composition and BMI was further investigated in human with the incorporation of macronutrient consumption and quantification of methanogenic Archaea. BMI was found to be negatively associated with the amount of fecal Bacteroides/Prevotella, E. coli and total bacteria. The intake of carbohydrate and dietary fiber were negatively associated with the amount of C. coccoides, and polyunsaturated fat intake was inversely correlated with the amount of fecal C. leptum, Bacteroides/Prevotella, and total bacteria. Fecal Archaea measured by breath CH4 was positively associated with the amount of fecal E.coli but negatively associated with C. coccoides and log Firmicutes/Bacteroidetes ratio. In conclusion, our findings suggest that fecal bacterial composition is associated with BMI, diet and fecal Archaea.

Keywords: Gut microbiota
Fecal Archaea
BMI
Diet
Adiposity
Microbial composition
Advisor: Comelli, Elena
Wolever, Thomas
The Effects of Helicobacter pylori Infection on Dendritic Cells

Helicobacter pylori infects the human gastric mucosa and induces a chronic gastritis that does not eliminate the pathogen. H. pylori infection is the primary risk factor for gastric cancer development. The host immune system is crucial for both bacterial elimination and tumor surveillance. The interaction between H. pylori and dendritic cells (DC), key orchestrators of the host immune response, was examined. H. pylori activated the Signal Transducer and Activator of Transcription 3 (STAT3) pathway, assayed using immunoblotting, in bone marrow-derived DCs. This blunted DC maturation, determined by CD86 and MHC II expression, in an autocrine/paracrine IL-10-dependent pathway. H. pylori infection stimulated the production of cytokines including IL-10, IL-12p40, and TNF-α as determined using ELISA and multiplex analysis. DC co-culture with T cells did not drive regulatory T cell development. These results demonstrate that H. pylori blunts DC maturation, which may play an important role in promoting bacterial persistence and disease.

Keywords: H. pylori
STAT3
dendritic cells
Helicobacter pylori
Advisor: Jones, Nicola
Genome-wide Association Study of Fat intake in Adolescence

Dietary preference for fat, which increases risk for obesity, is a complex behavior regulated in part by the brain-reward system. We conducted a genome-wide association study (GWAS) to search for loci associated with relative fat intake in 598 adolescents (12-18 years) who were recruited from the French-Canadian founder population. The GWAS identified a locus in the μ-opioid receptor gene (OPRM1, rs2281617, p=5.2x10-6), which encodes a receptor expressed in the brain-reward system and which has been shown previously to modulate fat preference in animals. The minor OPRM1 allele appeared to have a “protective” effect: it was associated with lower fat intake and lower body-fat mass, In addition, OPRM1 was associated with relative fat intake in an independent sample of 490 young adults. In summary, OPRM1 may modulate dietary preference for fat and hence the risk for obesity. Further studies are required to confirm our findings.

Keywords: Fat intake
Obesity
Genome-Wide Association Study
Opioid receptor mu 1 gene
Advisor: Pausova, Zdenka
Towards Examining FGF21 Secretion from Pancreatic Islets in a Microfluidic Device

Type II diabetes is characterized by impaired insulin-secretion from pancreatic β- cells. A novel endocrine factor, fibroblast growth factor 21 (FGF21) is produced by the liver and improves pancreatic β- cell function and survival. However, a state of FGF21- resistance has been described in obese mice and humans. This thesis examines (1) whether pancreatic islets temporally express FGF21 and (2) if high glucose and fat reduce transcript expression of FGF21 receptors in islets. This thesis further characterizes a novel microfluidic device that will be used to collect and assay FGF21. Our data indicate that palmitate induces maximal production of FGF21 mRNA in β- cells after 16 hours of stimulation through PPARγ. Secondly, we report that FGF21, glucose and palmitate do not cause FGF21-resistance by down-regulating receptor expression. Overall, we present a mechanism for the induction of FGF21 from islets, and describe a microfluidic device for culture and secretion studies.

Keywords: Diabetes
Microfluidics
Advisor: Rocheleau, Jonathan
NCS-1 Protein upregulation Facilitates Chronic Hypoxia-induced Respiratory Adaptation in Lymnaea stagnalis

Chronic hypoxia is a consequence of many common diseases, including sleep apnea and chronic lung disease. As there is no cure for many of these diseases, managing the symptoms of these diseases, including hypoxia is of great clinical importance. Preliminary data from the Feng lab show that the calcium binding protein neuronal calcium sensor-1 (NCS-1) is upregulated in the central nervous system of the freshwater pond snail Lymnaea stagnalis following chronic hypoxia treatment. This upregulation coincides with increased aerial respiratory activity. Furthermore, knockdown of NCS-1 attenuates hypoxia-induced facilitation of aerial respiration. Since this aerial respiratory activity is controlled by a respiratory central pattern generator (rCPG), it is hypothesized that hypoxia-induced upregulation of NCS-1 may regulate rCPG activity. Using intercellular sharp electrode recording, I show that in response to chronic hypoxia treatment, there is increased bursting activity and altered action potential profile in the pacemaker neuron of the rCPG, RPeD1. Knockdown of NCS-1 partially prevents these hypoxia-induced changes. Our findings suggest that NCS-1 upregulation is necessary for chronic hypoxia-induced respiratory adaptation.

Keywords: Hypoxia
NCS-1
Calcium binding protein
Advisor: Feng, Zhong-Ping
The Role of Chloroplast Localized Molecular Chaperone HSP90 in Arabidopsis thaliana Development

Heat shock protein 90 (HSP90) is a molecular chaperone and it has been implicated in late stages of de novo protein folding. In Arabidopsis thaliana, there are seven HSP90 isoforms. In this project, the function of chloroplast-localized AtHSP90.5 was studied by analyzing transgenic plants overexpressing AtHSP90.5FLAG. In addition, three independent transgenic lines showing AtHSP90.5 co-suppression were identified to have an albino phenotype in photosynthetic tissues along with stunted plant growth, reduced vegetative leaf size, and malformation of thylakoid membranes. Furthermore, potential AtHSP90.5 co-chaperones and client proteins were screened via yeast two-hybrid and affinity purification coupled with mass spectrometry, and nine potential AtHSP90.5 interactors were obtained. A novel client protein of AtHSP90.5, PsbO1 (Oxygen-evolving enhancer protein 1), was identified by yeast two-hybrid. The interaction between HSP90.5 and PsbO1 was further investigated and a putative role of AtHSP90.5 in promoting PsbO1 folding and targeting to thylakoid lumen is proposed.

Keywords: HSP90
Arabidopsis
Chloroplast
co-suppression
Development
Chaperone
Heat shock protein
PsbO1
yeast two-hybrid
oxygen-evolving enhancer protein 1
chloroplast HSP90
Advisor: Zhao, Rongmin
The Social Transmission of User-generated Memes

The popular concept of viral media is like the flu: once unleashed, it naturally infects all your friends. This work suggests that viral impact may not be determined by the content alone but also by the content’s creator as part of the Viral Feedback Loop. Participants interacted with a type of online meme called an image macro which has historically been shared virally. Participants made their own User-Generated Content (UGC) with Memelab, an image macro builder written for this experiment. Participants then shared their UGC online, which was longitudinally monitored to create a behavioural measure of viral impact. When sharing with a friend, participants’ predictions of how much their UGC would be liked was positively associated with viral impact. Intent to Share was modelled as a function of image macro content features and participant responses, which was then modelled with an Agent-based computer simulation.

Keywords: user-generated content
memes
Advisor: Cupchik, Gerald
Ignoring the Love: Attachment Avoidance and Empathic Accuracy in Romantic Conversations

Two studies examined the influence of attachment avoidance on accuracy in reading a romantic partner’s emotions (empathic accuracy) during positive couple interactions— conversations about love. Study 1 found that higher attachment avoidance was related to less accuracy in inferring a partner’s positive emotions during a conversation about love, but was not related to accuracy for negative emotions. Study 2 examined whether avoidant individuals’ lower empathic accuracy in love conversations could be increased by framing accuracy as unrelated to intimacy. The framing manipulation did not consistently alter avoidant individuals’ accuracy. However, there was some evidence that avoidant individuals performed worse when they believed accuracy reflected intimacy, compared to when accuracy was unrelated to intimacy. These results suggest that lower empathic accuracy may be a strategic defence avoidant individuals use to maintain emotional distance. By incorrectly reading their partner’s positive emotions, avoidant individuals may miss the relational benefits afforded by empathic accuracy.

Keywords: attachment
empathic accuracy
romantic relationships
social psychology
Advisor: MacDonald, Geoff
The Dynamic Role of Sphingolipids and their Regulatory Enzymes in Preeclampsia

Sphingolipids act as regulators of cell fate decisions. Ceramides (CERs) are key effector molecules regulating cell death. CERs metabolism is controlled by a balance between its breakdown and synthesis by the enzymes acid ceramidase (AC) and acid sphingomyelinase (ASM), respectively. We hypothesized that sphingolipid metabolism plays a role in proper placental development by establishing trophoblast cell fate and alterations in the pathways contribute to preeclampsia. CERs levels were increased in preeclamptic relative to normotensive preterm control placentae and this associated with decreased AC and ASM expression levels and altered glycosylation and activity of these enzymes, an effect caused by oxidative stress. Furthermore, C-16 ceramide or inhibiting AC activity induced autophagy in placental cells. In conclusion, altered expression of AC and ASM in preeclamptic placentae, induced by oxidative stress, are responsible for changes in the sphingolipid rheostat which may contribute to increased autophagy and trophoblast cell turnover characteristic of this disorder.

Keywords: Placenta
Sphingolipids
Preeclampsia
Advisor: Caniggia, Isabella
The Role of Central Glucagon Signaling in the Regulation of Glucose Homeostasis

Circulating glucagon activates hepatic G-protein coupled receptors to stimulate cAMP-dependent protein kinase A (PKA) signaling and increase glucose production (GP). The elevation of GP, however, is not sustained even in the presence of a continuous intravenous (i.v.) glucagon infusion that maintains elevated plasma glucagon levels. We here report that direct infusion of glucagon into the mediobasal hypothalamus of normal rats surprisingly inhibited GP during a pancreatic clamp. The GP-lowering effect required the activation of the hypothalamic glucagon receptor-cAMP-PKA pathway, while activation of the hypothalamic cAMP-PKA signaling alone was sufficient to lower GP. In a non-clamp setting, inhibition of the MBH glucagon receptor or cAMP-PKA signaling enhanced the acute ability of an i.v. glucagon injection to increase plasma glucose levels and GP in rats. Thus, we unveil a novel function of glucagon in the MBH that inhibits glucose production and counteracts the direct hepatic stimulatory effect of circulating glucagon in rats.

Keywords: glucagon
hypothalamus
glucose production
Advisor: Lam, Tony
Therapeutic Hypothermia: Exploring The Impact Of Processes Of Care On Outcomes After Cardiac Arrest

INTRODUCTION: The optimal processes of implementing therapeutic hypothermia after out-of-hospital cardiac arrest (OHCA) remain unclear. OBJECTIVE: Our objective was to evaluate the associations between the processes of cooling and patient outcomes. METHODS: A retrospective observational cohort study was performed on adult OHCA patients from November 1, 2007 to January 31, 2012 using two population-based datasets. Generalized estimating equation analyses were used to evaluate associations between temperature variables and patient outcomes. RESULTS: Higher baseline temperatures prior to cooling and slower rates of cooling were associated with patients having both good neurological outcomes and increased survival to hospital discharge. CONCLUSION: Higher baseline temperatures prior to cooling and slower rates of cooling were associated with improved neurological outcomes and survival to hospital discharge. Clinical trials are needed to assess the optimal cooling processes such as rate of cooling, temperature target, and cooling duration to achieve the best patient outcomes after OHCA.

Keywords: cardiac arrest
therapeutic hypothermia
processes of care
Advisor: Morrison, Laurie
Animal Models of Alzheimer’s Disease, Stroke, Type II Diabetes Co-morbidity: The Role of Hippocampal Adult Neurogenesis

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by a progressive decline in cognition and memory in the aging population. This progression is advanced by risk factors for vascular cognitive impairment, such as stroke and diabetes. The present study examines hippocampal adult neurogenesis in the animal models for combined stroke and AD, and combined type II diabetes and AD treatments. Stroke or AD treatment alone significantly impaired dendritic arborization of young neurons 3 weeks after the surgery. The combined treatment further reduced neuronal survival by over 90%. No significant changes in cell proliferation and neuronal survival were observed after combined type II diabetes and AD treatment. Our evidence suggests that combined stroke & AD can impact the survival of young neurons leading to more dramatic consequences in terms of possible cognitive decline. These effects on neurogenesis could contribute to the early onset and progression of Alzheimer’s dementia.

Keywords: Adult neurogenesis
Advisor: Wojtowicz, Martin
Applicability of Multidimensional Fractionation to Affinity Purification Mass Spectrometry Samples and Protein Phosphatase 4 Substrate Identification

Affinity-purification coupled to mass spectrometry (AP-MS) is gaining widespread use for the identification of protein-protein interactions. It is unclear however, whether typical AP sample complexity is limiting for the identification of all protein components using standard one-dimensional LC-MS/MS. Multidimensional sample separation is a useful for reducing sample complexity prior to MS analysis, and increases peptide and protein coverage of complex samples, yet the applicability of this approach to AP-MS samples remains unknown. Here I present work to show that multidimensional separation of AP-MS samples is not a cost-effective method for identifying increased peptide or protein coverage in these sample types. As such this approach was not adapted for the identification of putative Phosphoprotein Phosphatase 4 (PP4c) substrates. Instead, affinity purification coupled to one-dimensional LC-MS/MS was used to identify putative PP4c substrates, and semi-quantitative methods applied to identify possible PP4c targeted phosphosites in PP2A subfamily phosphatase inhibited (okadaic acid treated) cells.

Keywords: mass spectrometry
protein phosphatase 4
fractionation
Advisor: Gingras, Anne-Claude
Secretome Proteins as Candidate Biomarkers for Aggressive Thyroid Carcinomas

Using secretome proteomics and bioinformatics, analyses of non-aggressive and aggressive thyroid carcinoma (TC) cell lines revealed nine proteins as potential biomarkers for detection of aggressive TCs. Of these, APP, APLP2, AXL, PKM2, 14-3-3 zeta and SET were detected in patients’ sera by western blotting and showed significant differences in subcellular expression in benign and malignant tissues using immunohistochemistry (IHC). Membrane and cytoplasmic ALCAM expression was reduced in patients with poorly/undifferentiated (aggressive) TC compared to well-differentiated (non-aggressive) TC (p<0.001, AUC=0.865, sensitivity=82%, specificity=74%) as analyzed by IHC in 158 TCs and 45 benign nodules. Kaplan-Meier survival analysis revealed reduced disease-free survival for TC patients with lower ALCAM expression (median survival 7.3 years compared to 13.5 years for patients with higher expression, p=0.002). ALCAM sera levels were elevated in aggressive versus non-aggressive TC patients (p=0.04), as measured by ELISA. ALCAM may potentially serve as a useful diagnostic and prognostic marker for aggressive TC.

Keywords: thyroid cancer
biomarker
proteomics
secretome
tissue
serum
Advisor: Walfish, Paul
P. berghei ANKA Experimental Malaria Infection Alters Drug Transporter and Drug Metabolizing Enzyme Expression in Pregnancy

A P. berghei ANKA mouse model of malaria infection was employed to investigate disease-induced changes in an array of genes that impact drug disposition in pregnancy. We demonstrate the reduced expression of a number of transporters in the placenta of infected dams relative to uninfected dams, in addition to altered expression of transporters and Cyp3a11 in maternal and fetal tissues. The impact of Complement 5a receptor (C5aR) activation during malaria infection on transporter expression in liver and placenta was also examined in C5aR-/- infected dams. Increased expression of Abcb1a and Abcg2 in the placenta of C5aR-/- infected dams was observed when compared to wildtype-infected dams. Furthermore, whereas expression of placental Abcb1a and Abc1b were decreased in infected wildtype dams, their expression was unchanged in C5aR-/- infected dams. Collectively, if these findings translate to malaria infection in human pregnancy, the systemic clearance and maternofetal disposition of therapeutics and other xenobiotics may be altered.

Advisor: Piquette-Miller, Micheline
Asians With IgA Nephropathy Have An Increased Risk of Progression to End-stage Renal Disease

IgA nephropathy (IgAN) is a common cause of end-stage renal disease (ESRD) in Asia; while this may be partly due to a higher prevalence of disease, it is unknown if it also reflects racial differences in the risk of progression to ESRD. To determine if Asians with IgAN have a higher risk of ESRD, I analyzed a cohort of 202 Asians and 467 non-Asians with IgAN in Canada (mean follow-up 46 months). The primary outcome of ESRD occurred in 213 patients. After adjusting for age, sex, eGFR, medication use, MAP and proteinuria, the HR for ESRD in Asians vs non-Asians was 1.56 (95%CI 1.10-2.22 p=0.01). These results were supported by a 1.62ml/min/1.73m2/year faster rate of eGFR decline in Asians (95%CI -3.19--0.5 p=0.04) and an increased risk of a 50% reduction in eGFR (HR=1.81 95%CI 1.25-2.62 p=0.002). These results suggest that Asian ancestry may be an important risk factor for renal progression in IgAN.

Keywords: IgA nephropathy
race
ethnicity
end-stage renal disease
renal progression
Advisor: Reich, Heather