Browsing by Author "Hurst Radke, Nicole"
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Item The dose makes the poison: non-linear behavioural response to CO2-induced aquatic acidification in zebrafish (Danio rerio)(2021) Hamilton, Trevor; Hurst Radke, Nicole; Bajwa, Jasmin; Chaput, Shayna; Tresguerres, MartinCO2-induced aquatic acidification is predicted to affect fish neuronal GABAA receptors leading to widespread behavioural alterations. However, the large variability in the magnitude and direction of behavioural responses suggests substantial species-specific CO2 threshold differences, life history and parental acclimation effects, experimental artifacts, or a combination of these factors. As an established model organism, zebrafish (Danio rerio) can be reared under stable conditions for multiple generations, which may help control for some of the variability observed in wild-caught fishes. Here, we used two standardized tests to investigate the effect of 1-week acclimatization to four pCO2 levels on zebrafish anxiety-like behaviour, exploratory behaviour, and locomotion. Fish acclimatized to 900 μatm CO2 demonstrated increased anxiety-like behaviour compared to control fish (~480 μatm), however, the behaviour of fish exposed to 2200 μatm CO2 was indistinguishable from that of controls. In addition, fish acclimatized to 4200 μatm CO2 had decreased anxiety-like behaviour; i.e. the opposite response than the 900 μatm CO2 treatment. On the other hand, exploratory behaviour did not differ among any of the pCO2 exposures that were tested. Thus, zebrafish behavioural responses to elevated pCO2 are not linear; with potential important implications for physiological, environmental, and aquatic acidification studies.Item Vision of conspecifics decreases the effectiveness of ethanol on zebrafish behaviour(2021) Dean, Rachel; Hurst Radke, Nicole; Velupillai, Nirudika; Franczak, Brian C.; Hamilton, TrevorAquatic organisms in pharmacology and toxicology research are often exposed to compounds in isolation prior to physiological or behavioural testing. Recent evidence suggests that the presence of conspecifics during a stressful event can modulate behavioural outcomes (called ‘social buffering’) when testing occurs within the same context. It is unknown, however, whether the social environment during exposure interacts with the efficacy of anxiety-altering substances when subsequently tested in the absence of conspecifics. In this study, zebrafish were individually exposed to habitat water or ethanol (1.0% vol/vol) while untreated conspecifics were visually present or absent during dosing. Using the novel object approach test, a validated test of boldness and anxiety-like behaviour, we observed significantly greater effects of ethanol in isolated fish, compared to fish with a view of conspecifics during dosing. These results were not explained by altered locomotion during exposure, which might otherwise increase drug uptake. This highlights the need to consider the social environment during exposure when conducting and interpreting behavioural research involving drug or toxicant exposure.