UVicSpace | Institutional Repository

 

UVicSpace is the University of Victoria’s open access scholarship and learning repository. It preserves and provides access to the digital scholarly works of UVic faculty, students, staff, and partners. Items in UVicSpace are organized into collections, each belonging to a community.

For more information about depositing items, see the UVicSpace LibGuide.

 

Recent Submissions

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Molecular basis for differential activation of p101 and p84 complexes of PI3Kγ by Ras and GPCRs
(Cell Reports, 2023) Rathinaswamy, Manoj K.; Jenkins, Meredith L.; Duewell, Benjamin R.; Zhang, Xuxiao; Harris, Noah J.; Evans, John T.; Stariha, Jordan T. B.; Dalwadi, Udit; Fleming, Kaelin D.; Ranga-Prasad, Harish; Yip, Calvin K.; Williams, Roger L.; Hansen, Scott D.; Burke, John
Class IB phosphoinositide 3-kinase (PI3Kγ) is activated in immune cells and can form two distinct complexes (p110γ-p84 and p110γ-p101), which are differentially activated by G protein-coupled receptors (GPCRs) and Ras. Using a combination of X-ray crystallography, hydrogen deuterium exchange mass spectrometry (HDX-MS), electron microscopy, molecular modeling, single-molecule imaging, and activity assays, we identify molecular differences between p110γ-p84 and p110γ-p101 that explain their differential membrane recruitment and activation by Ras and GPCRs. The p110γ-p84 complex is dynamic compared with p110γ-p101. While p110γ-p101 is robustly recruited by Gβγ subunits, p110γ-p84 is weakly recruited to membranes by Gβγ subunits alone and requires recruitment by Ras to allow for Gβγ activation. We mapped two distinct Gβγ interfaces on p101 and the p110γ helical domain, with differences in the C-terminal domain of p84 and p101 conferring sensitivity of p110γ-p101 to Gβγ activation. Overall, our work provides key insight into the molecular basis for how PI3Kγ complexes are activated.
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Correlates of hazardous alcohol drinking among trans and non-binary people in Canada: A community-based cross-sectional study
(Drug and Alcohol Dependence, 2023) Tran, Gioi Minh; Lachowsky, Nathan; Urbanoski, Karen A.; Scheim, Ayden I.; Bauer, Greta R.
Purpose: Transgender and non-binary people (TGNB) have a higher rate of heavy episodic drinking than cisgender people; however, extant knowledge about predictors of hazardous alcohol drinking (HAD) among different TGNB groups is limited. This study examined predictors of HAD in a national sample of TGNB people in Canada. Methods: Logistic regression models were fit to examine the effects of 1) minority stressors and 2) stress-buffering factors on the likelihood of HAD, stratified by gender, among 2324 TGNB individuals from the Trans PULSE Canada survey, a cross-sectional survey conducted in 2019 among trans and non-binary people aged 14+ in Canada. Results: Almost 17% of participants reported past-year HAD. Lifetime day-to-day and lifetime major discrimination were associated with higher odds of HAD in the full sample [(AOR=1.37, 95% CI: 1.30, 1.44) and (AOR=1.69, 95% CI: 1.55, 1.86) respectively], and across all gender groups. Social support was associated with lower odds of HAD in trans men, non-binary people assigned female at birth (NB-AFAB), and non-binary people assigned male at birth (NB-AMAB) groups, but with higher odds of HAD in the trans women group. Misgendering was associated with lower odds of HAD in trans men and NB-AFAB, but higher odds of HAD in trans women and NB-AMAB. Mixed effects of gender distress, gender positivity, and gender-affirming medical care were also reported across groups. Conclusion: The study provided a more detailed understanding of the predictors of HAD across four TGNB groups. Public health interventions should focus on structural discrimination and social support for TGNB people.
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Psychological mediators of the associations between pandemic-related stressors and suicidal ideation across three periods of the COVID-19 pandemic in Canada
(Journal of Affective Disorders, 2023) Turner, Brianna; Switzer, Andrew C.; Welch, Brooke E.; Legg, Nicole K.; Gregory, Madeline A.; Phiri, Peter; Rathod, Shanaya; Paterson, Theone S. E.
Background: The COVID-19 pandemic's mental health impact is well-established. While early evidence suggested suicide deaths remained stable or declined, suicidal ideation (SI) became more prevalent than before the pandemic. Our study: (1) examined the prevalence and distribution of SI among Canadian adults, (2) compared SI among those with and without pre-existing mental illnesses, and (3) evaluated associations between pandemic-related stressors (i.e., unemployment, insecure employment, loss of income, medical vulnerability, COVID-19 exposure) with SI, and whether such associations were mediated by depression, thwarted belongingness, perceived burdensomeness, or perceived discrimination. Methods: The sample was comprised of data gathered at three timepoints (Wave 1 08/18/2020–10/01/2020, n = 6629; Wave 2 12/21/2020–03/31/2021, n = 5920; Wave 3 09/07/2021–12/07/2021, n = 7354). Quota-based responses from survey research panels which matched the geographic, age, and sex distribution of the Canadian population were supplemented with convenience-sampled responses. Results: The prevalence of SI was 4.1 % (Wave 1), 5.3 % (Wave 2), and 5.8 % (Wave 3). Odds of SI were higher for respondents under the age of 35 years and with pre-existing mental illnesses. SI was associated with quarantining due to suspected or confirmed COVID-19 exposure, potential COVID-19 exposure at work, medical vulnerability toward COVID-19, insecure employment or unemployment, and income loss. These associations were mediated by psychological experiences, particularly depression and thwarted belongingness. Limitations: This cross-sectional, observational study cannot establish temporality or causality. Conclusion: Results highlight groups who may benefit from enhanced screening for depression and suicide risk. Reducing depression and increasing sense of belonging should be prioritized.
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Bycatch-threatened seabirds disproportionally contribute to community trait composition across the world
(Global Ecology and Conservation, 2024) Richards, Cerren; Cooke, Rob; Bowler, Diana E.; Boerder, Kristina; Bates, Amanda
Human pressures in the ocean are restructuring biological communities, driving non-random extinctions, and disrupting marine ecosystem functioning. In particular, fisheries bycatch, the incidental mortality of non-target species, is a major threat to seabirds worldwide. Direct bycatch data are often scarce. Instead, leveraging trait-based analyses with fine-scale fisheries data could answer fundamental questions about spatial patterns of bycatch-threatened species and facilitate targeted conservation strategies. Here, we combine a dataset of species' traits and distribution ranges for 361 seabird and sea duck species with spatially resolved fishing effort data for gillnet, longline, trawl, and purse seine gears. First, we quantify geographic patterns of seabird community traits. Second, we describe how community traits could shift under local extinction scenarios in areas where bycatch-threatened seabirds spatially overlap with fishing activities. These objectives allow us to highlight the collective contribution of species currently threatened from bycatch to ecosystem functioning. We reveal distinct spatial variation in the community weighted mean of five seabird traits (body mass, generation length, clutch size, diet guild, and foraging guild) are evident. Moreover, our results show that fisheries bycatch is selectively removing a distinct suite of traits from the community within particular oceanic regions. Specifically, fisheries bycatch is threatening species with larger body masses, slower reproductive speeds (smaller clutch sizes and longer generation lengths), and specialised diet and foraging guilds. The spatial non-uniformity of the community trait shifts suggests that within specific marine regions, communities have limited redundancy and therefore may have less insurance to buffer against declines in ecosystem functioning. Our extinction scenario warns that seabirds currently threatened from fisheries bycatch substantially contribute to community functional composition. Management actions that incorporate species’ traits and fine-scale fisheries datasets as tools for marine spatial planning will add an important dimension when evaluating the success of conservation initiatives.
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Testing umbrella species and food-web properties of large carnivores in the Rocky Mountains
(Biological Conservation, 2023) Steenweg, Robin; Hebblewhite, Mark; Burton, Cole; Whittington, Jesse; Heim, Nikki; Fisher, Jason Thomas; Ladle, Andrew; Lowe, Winsor; Muhly, Tyler; Paczkowski, John; Musiani, Marco
Despite criticisms, the umbrella species concept remains a fundamental conservation tool for protecting biodiversity in the face of global change, yet it is rarely tested. Food web theory provides a tool to test both umbrella-species' suitability and their ecological function, which we investigate in a large-mammal food web. Using data from 698 camera trap locations in the Canadian Rockies, we develop hierarchical occupancy models to predict the co-occurrence of 16 large mammal species. We draw upon previous diet studies in the Canadian Rockies to describe the meta food-web (meta-web) for these species. Next, we filtered the meta-web using predicted occupancy to estimate realized food webs at each camera location. We tested the umbrella species concept using predicted occupancy across all 698 camera sites. We then tested for carnivore effects using realized food webs on 5 food-web properties: species richness, links, connectance, nestedness and modularity using generalized linear models while accounting for landscape covariates known to affect food web dynamics. Our multispecies occupancy models reflected factors previously demonstrated to affect large mammal occurrence. Our results also demonstrated that grizzly bear (Ursus horribilis), a generalist carnivore, was the best umbrella carivore species, and explained species richness the best. When considering food web properties, however, wolves (Canis lupus) and cougars (Felis concolor) served as better umbrellas that also captured food web properties such as connectance, links and nestedness that better reflect ecological interactions. Our results support the role of large carnivores as umbrella and ecologically interactive species in conservation planning.