Physiological and Behavioural Regulation of Animal Stress Responses

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Animals respond to stress by engaging in strategies to cope with the disruption in homeostasis. If the stress is prolonged or severe, these stress-coping mechanisms may be insufficient and the animal has increased susceptibility to disease and/or death. The long-term goal of my research program is focused on understanding feedback amongst behavioural, physiological and cellular stress response strategies in animals. My motivation is twofold: 1) to understand how aquatic animals are dealing with a changing, often stressful environment and 2) to use fish and their cells as models to understand fundamental stress-coping strategies. In the short term, we will address how the physiological (Obj 1) and behavioural (Obj 2) state of the animal influences its response and tolerance to stress. I am proposing ecologically relevant whole-animal experiments and mechanistic cell-based experiments to address two short-term objectives. The first uses osmotic and heat stress in elasmobranchs and hagfishes to investigate the relationship between chemical and molecular chaperones. Cells use these chaperones to mitigate stress-induced cellular damage and assist with proper protein folding. The molecular chaperones, of which the heat shock proteins (HSPs) are a well-studied example, bind directly to proteins and assist with folding. Chemical chaperones, such as the osmolyte, trimethylamine oxide (TMAO), on the other hand, interact indirectly with proteins to inhibit protein aggregation. The overarching hypothesis here is that animals with high concentrations of chemical chaperones will have lower concentrations of molecular chaperones. Our findings could reveal novel roles for chaperones during stress and provide insight into how the two chaperones systems are fundamentally integrated in cells. My second objective will address how social stress affects responses to thermal stress. Here, we will use the mangrove rivulus fish, the only known selfing hermaphroditic vertebrate, to isolate genetics and tease apart the contributions of environmental variation on behavioural and physiological phenotypes. With this unique model, we will determine thermal physiology and tolerance between and within isogenic lineages and investigate how social behaviour, in the form of aggression, affects an animal’s response to environmental change. We will also determine the molecular signatures of social interactions and the thermal stress response as we predict that these phenotypes may be regulated by common mechanisms. The ability to use genotype as an independent variable to examine variability in behaviour and thermal physiology will help to disentangle genetic and environmental effects on the physiology of stress resistance. Overall, this research will provide a greater understanding of the physiological underpinnings of stress tolerance allowing us to make informed predictions on the impact of environmental change on aquatic animals.