Vanier celebrates nation’s finest graduate students

Four Western PhD candidates have been named among 167 nationwide recipients of the 2017-18 Vanier Canada Graduate Scholarships – two from the natural sciences and engineering competition, two from the health sciences competition. Each winner will receive $50,000 annually for up to three years. Vanier Scholars are selected each year based on leadership skills and a high standard of scholarly achievement in disciplines that span the social sciences and humanities, the natural sciences and engineering, and the health sciences.

Christy Caudill
PhD candidate in Geology & Planetary Science; Earth Sciences Department/Centre for Planetary Science and Exploration (CPSX)
Comparative Planetology: Formation and Evolution of Impact Melt Deposits with Insights into Martian Soil Production and Past Environments

Hydrated minerals (e.g. clays) observed on the ancient surfaces of Mars have been used as an indication of climatic conditions that allowed liquid water to be stable on the surface, providing a timeframe for habitability. Through the comparative mapping of clay-rich impact deposits on Mars and Earth, Christy Caudill investigates the hypothesis that some hydrated minerals identified in ancient terrains of Mars were produced sub-surface through impact cratering processes, and therefore may not necessarily be indicative of an extended period of warm, wet conditions on ancient Mars.

In this study, she will map clay-rich impact deposits at the Ries Impact Structure, Germany, using a novel field-based hyperspectral imager. In parallel, spectral imaging data acquired by a Mars-orbiting instrument will allow mapping of the mineralogy of identified impact deposits (including clays). This will be the first known study which directly compares terrestrial field-based and Mars orbitally-based spectral data. Furthermore, analysis of the terrestrial Ries impact deposits will employ traditional mineralogical and geochemical laboratory techniques, acting as a “ground-truthing” for the composition of analogous impact deposits on Mars. Scientists hypothesize that voluminous clays would have formed early in Mars’ history during a period of heavy impact cratering without the necessity of long-lived, stable surface water.

Through this work, Caudill will assess the formation conditions for minerals on ancient terrains of Mars and address the current assumptions regarding its early habitability. This one-to-one comparison between data will result in better analogous study, a more rigorous representation of Martian past and present geologic processes, and assist in more productive targeting for future Mars exploration.

Leanne Grieves
PhD Biology (Evolution & Ecology)
Major histocompatibility complex diversity and olfactory mate choice in a songbird

Leanne Grieves’ research explores whether songbirds use smell to evaluate the immune genes of potential mates. She will compare the immune genes of two song sparrow populations in Ontario.

In vertebrate animals, an essential part of immune defense is a set of genes called the major histocompatibility complex (MHC). MHC genes have many alternate forms called alleles. Since high MHC allelic diversity can increase disease resistance, animals should prefer mates with MHC genes different from their own. The resulting offspring should have both greater MHC diversity and disease resistance. Because this is so important, animals are likely able to assess the MHC of potential mates. Several taxa use smell, but it is not known how birds assess MHC. Most birds secrete preen oil containing chemicals that can reflect MHC genotype.

Using behavioural trials, Grieves will test whether song sparrows prefer preen oil from MHC-dissimilar birds of the opposite sex. Her research may reveal that scent-based communication in birds is more common than previously believed and will provide insight into key research areas such as mate choice and disease ecology.

Marat Slessarev
PhD, Medical Biophysics
Improving cognitive outcomes in critical illness survivors: mechanistic multimodal imaging approach

Critical illness survivors develop long-term cognitive impairment that affects their function, prevents return to work, and places a huge burden on families, caregivers and society. It is believed this impairment is a consequence of different disease processes and therapies delivered during patients’ stay in the intensive care unit.

Marat Slessarev plans to tackle this problem in three phases. First, he will develop web-based brain tests to track cognitive changes in critical illness survivors from acute admission, through recovery and into survivorship. This will enable him to measure severity of cognitive impairment in individual patients, monitor their recover, and determine what interventions lead to better cognitive outcomes. Second, he will use novel imaging methods to assess whether brain blood flow, blood pressure and carbon dioxide contribute to development of cognitive impairment. Third, he will test if various interventions (e.g. optimizing blood pressure and carbon dioxide levels, early passive exercise) can be used to improve cognitive outcomes.

Slessarev’s research program combines discovery of underlying disease mechanisms causing cognitive impairment and development of potential interventions to improve cognitive outcomes in critical illness survivors, with a vision to maintain their cognitive vitality, promote functional independence and reduce burden of families, caregivers and society.

Charles Yin
MD/PhD (Department of Microbiology and Immunology)
Characterization of defective macrophage efferocytosis within atherosclerotic lesions

Heart disease and stroke are leading causes of death and disability in Canada. The most common cause of heart disease and stroke is atherosclerosis, a disease where fatty material builds up to form plaques on blood vessel walls. These plaques grow in size and can become large enough to rupture. Pieces of a ruptured plaque can clog blood vessels and stop blood flow, resulting in heart attack or stroke.

When a plaque begins to form, cells of the immune system called macrophages move into the plaque and remove dying cells from the plaque to limit its growth. However, through a process still incompletely understood, macrophages eventually lose their ability to do this over time. When this happens, macrophages become trapped in the plaque, where they begin to die. Their death releases molecules into the plaque that causes it to become more likely to rupture.

Charles Yin’s research aims to identify what causes macrophages to become unable to remove dying cells from the plaque by directly studying macrophages from patients with atherosclerosis. Using this approach, he will gain an understanding of how macrophages become dysfunctional in atherosclerosis. The outcomes of his research could lead to new ways to diagnose and treat atherosclerosis.