Browsing by Author "Bajwa, Jasmin"
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Item Chondroitin Sulphate acts as an 'alarm cue' in zebrafish(2020) Bajwa, Jasmin; Hamilton, TrevorZebrafish are conspecific organisms that are sensitive to the use of ‘alarm cues’, a procedure in behavioural fish research used to create experimental stress responses. We used a commercially available chemical compound, chondroitin sulphate, extracted from shark cartilage, as the possible ‘alarm cue’. This chemical compound controls for standardization errors common with alarm cues extracted from individual fish. We conducted an open field test, followed by a novel object approach test, to assess the behavioural responses consequential of 30 minutes of chondroitin sulphate exposure at different concentrations (ie. 1, 10, and 100 mg/L). Secondly, we locally applied 250 μL of 100 mg/L of chondroitin sulphate to the centre of an open field arena, and again assessed behavioural responses. The time individual fish spent in the centre, transition, and thigmotaxis zones was examined, along with the distance each fish moved and the time spent immobile. There was a significant increase in the time fish spent in the thigmotaxis zone during the novel object approach test after chondroitin sulphate exposure. We also found that fish in the experimental group spent more time in the thigmotaxis zone following the injection of chondroitin sulphate, compared to fish in the control group. These findings suggest this compound can be used as a reliable alarm cue stimulus in zebrafish.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.