Tuesday/Mardi, May/Mai 7
11:00-13:00
William S. Hoar Award/Prix
Student Talks/Présentations étudiantes
Location/Lieu: Ballroom A and B
Chair/Animé par: Tamara Franz-Odendaal (Mount Saint Vincent University, CSZ-SCZ first vice-president)
11:00-11:10
Introduction and Welcome
11:10-11:30
Cadonic, I. G.¹, Heath, J. W.², Dixon, B.¹, Craig, P. M.¹
¹Department of Biology, University of Waterloo, Waterloo, Canada; ²Yellow Island Aquaculture, Heriot Bay, Canada
Reduced cardiac performance in triploid chinook salmon (Oncorhynchus tshawytscha) during an extreme temperature exposure
Pressures associated with climate change will negatively impact wild fish populations; therefore, preserving genetic diversity in these populations will increase the potential for their successful adaptation to an altered environment. Farming of sterile triploid fish is more sustainable since any aquaculture escapees are unable to breed, preventing reduction of wild stock genetic diversity. However, triploid fishes respond poorly to stressful conditions and will be negatively affected by climate change as well. The objective of this study is to characterize cardiac performance of diploid and triploid Chinook salmon (Oncorhynchus tshawytscha) during and after recovery from an acute temperature challenge. Diploid and triploid fish were surgically implanted with heart rate loggers (Star-Oddi) to assess how both ploidies responded during a critical thermal maximum (Ctmax) experiment. Fish were then allowed to recover for one hour after reaching Ctmax to assess whether increased ploidy influences cardiac recovery at a molecular level. Although both ploidies had similar Ctmax temperatures, triploids became agitated ~1°C earlier than diploids. Additionally, triploids had an earlier onset of cardiac arrhythmia, indicating that their hearts fail at lower temperatures. Both ploidies had similar heat shock protein expression during recovery; however, triploids had elevated myoglobin expression in both the ventricle and atrium. Furthermore, in the ventricle, carbonic anhydrase 4 had lower expression in triploids while having higher expression of the miRNA (miR-24a-5p) that is predicted to regulate it. Overall, this data indicates that triploids have altered cardiorespiratory gene expression in the heart which could explain their poor temperature tolerance.
11:30-11:50
Boyd, A., Blewett, T.A.
University of Alberta Department of Biological Sciences, Edmonton T6G 2E9, Canada
Bridging the gap between standardized laboratory tests and environmental outcomes: investigating organic ultraviolet filter toxicity to freshwater invertebrates Daphnia magna and Daphnia pulex
To accommodate the growing need for physiology research due to continued anthropogenic change of natural environments, standardized test guidelines have been developed that use simplified models to simulate complex real-world environments. These methods require that test organisms are reared in stable conditions to control life history traits such as genetic ancestry and prior exposure to chemical or biological stressors to minimize the effects of biological variation across research groups. By using data generated from these highly specific tests, critical assumptions are made that testing organisms raised in stable laboratory environments for a set duration of time produces data representative of real-world outcomes. These assumptions were tested by exposing Daphnia to organic ultraviolet filters (UVFs), contaminants of concern that have been demonstrated to cause toxicity at environmental concentrations. Daphnids exposed to UVFs experienced 60% mortality and 40% decreased reproduction over the standard first generation of exposure but were capable of gradual acclimation to continuous exposure across subsequent generations until no impairment was evident by the 4th generation. Additional studies comparing the responses of the laboratory lineage of D. pulex to a wild population revealed that each population differs in sensitivity to UVFs on a case-by case basis, as each tested chemical severely impacted one population type but not the other, highlighting fundamental differences in each population’s physiology. This research identifies several shortcomings of applying standardized research to real-world environments and highlights the necessity to understand how the methods used to conduct biological research impact the conclusions drawn from resulting data.
11:50-12:10
Rowsey, L.E., Speers-Roesch, B.
Department of Biological Sciences, University of New Brunswick, Saint John, Canada
Do thermal constraints on physiological performance explain the use of winter dormancy among fishes?
During winter, certain fish species remain active while others become dormant, which is characterized by low metabolic rate, fasting, and negligible or negative growth. We hypothesized that winter dormancy is a survival strategy that arises in poleward species that tolerate severe, uncompensated constraints of cold on physiological performance. To date, we have measured the metabolic, exercise, and digestive performance of cunner (Tautogolabrus adspersus), a model winter-dormant fish, acclimated or acutely exposed to a wide range of temperatures (2-26°C). Contrary to our hypothesis, we found partial cold compensation of nearly all metabolic and exercise performance metrics studied, similar to winter-active species. Further, after bypassing the behavioural fasting response during dormancy using repeated force-feeding during cold acclimation, cunner were able to digest food and subsequently exhibit positive growth compared to negative growth of the voluntarily fasting fish. Only responsiveness to stimuli during the C-start escape response was greatly constrained in the cold even after acclimation, suggesting a thermal sensory limitation that may help explain the need to become dormant. To further explore this idea, we measured the C-start escape performance of six phylogenetically-diverse species along the spectrum of overwintering strategies from winter-dormant to winter-lethargic to winter-active. As we predicted, responsiveness was greater and more plastic in the winter-lethargic and -active species compared to -dormant species. While most physiological performance traits in cold dormant fish remain robust, impaired responsiveness to C-start stimuli may be a weak thermal link driving dormancy as an overwintering strategy among fishes.
12:10-12:30
Léger, A.¹², Aminot, M.¹², Jorissen, S.⁴, Hébert-Chatelain, E.²³, Pichaud, N.¹²
¹Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada; ²New Brunswick Centre for Precision Medicine, Moncton, NB, Canada; ³Department of Biology, Université de Moncton, Moncton, NB, Canada; ⁴Department of Biology, KU Leuven, Leuven, Belgium
The powerhouse of the hive: Seasonal differences in mitochondrial uncoupling, ATP and ROS production in honey bees
Because of their different roles within the hive, summer and winter honey bees (Apis mellifera) exhibit distinct phenotypes. We have recently demonstrated that honey bees’ mitochondria undergo drastic changes between seasons. More specifically, winter bees have lower CI-linked respiration but increased mtG3PDH- and CII-linked respiration. We hypothesize that this would lead to a decreased ATP production because mtG3PDH and CII do not directly contribute to proton pumping. Given the high energy requirements of winter bees, which shiver their thoracic muscles to keep the queen warm, we explored mechanisms allowing non-shivering thermogenesis that do not require ATP, specifically uncoupling proteins (UCP). Thus, in this study we investigated the seasonal differences in mitochondrial oxygen consumption, ATP production, site-specific reactive oxygen species (ROS) production and UCP activity in honey bees. Our results demonstrate that even though CI-linked respiration is diminished in winter bees, ATP production with CI substrates increased, suggesting that CI is more efficient in winter bees, likely to sustain shivering thermogenesis. On the other hand, succinate and G3P did not contribute to ATP production. Differences were also detected in terms of ROS production; overall, summer bees produced less ROS than all other seasons. Important UCP activity was detected in summer bees whereas winter bees displayed very little, or no UCP activity, suggesting that UCPs are not involved in thermogenesis in honey bees. However, increased UCP activity in the summer could help minimise ROS production, which might explain the low rates obtained in summer.
12:30-12:50
Van Wert, J. C.¹, Birnie-Gauvin, K.², Robinson, K. A.³, Patterson, D. A.³, Eliason, E. J.¹
¹Department of Ecology, Evolution & Marine Biology, University of California, Santa Barbara, CA 93106, USA; ²Section for Freshwater Fisheries and Ecology, National Institute of Aquatic Resources, Technical University of Denmark, Silkeborg, Denmark; ³Fisheries and Oceans Canada, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
Heart function and pathology are linked to the migration success of Pacific salmon
The upstream spawning migration is a demanding feat for Pacific salmon (Oncorhynchus spp.). Relying on endogenous energy reserves, salmon often swim in warm water for weeks against strong currents and complex hydraulic conditions (e.g. rapids) to reach natal spawning grounds. Cardiac structure and function may determine migration outcomes. During migration, the heart’s excessive beating can damage the coronary artery, causing lesions that reduce oxygen supply to the compact myocardium (i.e., coronary arteriosclerosis). We sampled sockeye salmon (O. nerka) across various stages of their migration, including in the ocean, at the river entry, in a subset that failed part-way through migration, and at their spawning grounds, for signs of coronary arteriosclerosis and health status through blood chemistry. Coronary arteriosclerosis was most severe in fish that strayed and in fish sampled at the spawning grounds, occluding up to 25% of blood flow. We identified a suite of cardiorespiratory metrics associated with an unsuccessful migration. Fish that strayed showed signs of hyperkalemia (high plasma potassium levels, impairs heart contractility), advanced sexual maturity (relatively low plasma estradiol and testosterone concentrations), elevated plasma cardiac troponin C (indicative of O2 limitation to the heart), and less relative compact myocardium (reduced reliable oxygen supply to the heart). Our results underpin the importance of heart function in migration success. Its pathology, chemistry, and potential for a plastic morphological response may serve as an indicator of how hard the fish have worked and help describe and predict migration success.
Chair/Animé par: Tamara Franz-Odendaal (Mount Saint Vincent University, CSZ-SCZ first vice-president)
11:00-11:10
Introduction and Welcome
11:10-11:30
Cadonic, I. G.¹, Heath, J. W.², Dixon, B.¹, Craig, P. M.¹
¹Department of Biology, University of Waterloo, Waterloo, Canada; ²Yellow Island Aquaculture, Heriot Bay, Canada
Reduced cardiac performance in triploid chinook salmon (Oncorhynchus tshawytscha) during an extreme temperature exposure
Pressures associated with climate change will negatively impact wild fish populations; therefore, preserving genetic diversity in these populations will increase the potential for their successful adaptation to an altered environment. Farming of sterile triploid fish is more sustainable since any aquaculture escapees are unable to breed, preventing reduction of wild stock genetic diversity. However, triploid fishes respond poorly to stressful conditions and will be negatively affected by climate change as well. The objective of this study is to characterize cardiac performance of diploid and triploid Chinook salmon (Oncorhynchus tshawytscha) during and after recovery from an acute temperature challenge. Diploid and triploid fish were surgically implanted with heart rate loggers (Star-Oddi) to assess how both ploidies responded during a critical thermal maximum (Ctmax) experiment. Fish were then allowed to recover for one hour after reaching Ctmax to assess whether increased ploidy influences cardiac recovery at a molecular level. Although both ploidies had similar Ctmax temperatures, triploids became agitated ~1°C earlier than diploids. Additionally, triploids had an earlier onset of cardiac arrhythmia, indicating that their hearts fail at lower temperatures. Both ploidies had similar heat shock protein expression during recovery; however, triploids had elevated myoglobin expression in both the ventricle and atrium. Furthermore, in the ventricle, carbonic anhydrase 4 had lower expression in triploids while having higher expression of the miRNA (miR-24a-5p) that is predicted to regulate it. Overall, this data indicates that triploids have altered cardiorespiratory gene expression in the heart which could explain their poor temperature tolerance.
11:30-11:50
Boyd, A., Blewett, T.A.
University of Alberta Department of Biological Sciences, Edmonton T6G 2E9, Canada
Bridging the gap between standardized laboratory tests and environmental outcomes: investigating organic ultraviolet filter toxicity to freshwater invertebrates Daphnia magna and Daphnia pulex
To accommodate the growing need for physiology research due to continued anthropogenic change of natural environments, standardized test guidelines have been developed that use simplified models to simulate complex real-world environments. These methods require that test organisms are reared in stable conditions to control life history traits such as genetic ancestry and prior exposure to chemical or biological stressors to minimize the effects of biological variation across research groups. By using data generated from these highly specific tests, critical assumptions are made that testing organisms raised in stable laboratory environments for a set duration of time produces data representative of real-world outcomes. These assumptions were tested by exposing Daphnia to organic ultraviolet filters (UVFs), contaminants of concern that have been demonstrated to cause toxicity at environmental concentrations. Daphnids exposed to UVFs experienced 60% mortality and 40% decreased reproduction over the standard first generation of exposure but were capable of gradual acclimation to continuous exposure across subsequent generations until no impairment was evident by the 4th generation. Additional studies comparing the responses of the laboratory lineage of D. pulex to a wild population revealed that each population differs in sensitivity to UVFs on a case-by case basis, as each tested chemical severely impacted one population type but not the other, highlighting fundamental differences in each population’s physiology. This research identifies several shortcomings of applying standardized research to real-world environments and highlights the necessity to understand how the methods used to conduct biological research impact the conclusions drawn from resulting data.
11:50-12:10
Rowsey, L.E., Speers-Roesch, B.
Department of Biological Sciences, University of New Brunswick, Saint John, Canada
Do thermal constraints on physiological performance explain the use of winter dormancy among fishes?
During winter, certain fish species remain active while others become dormant, which is characterized by low metabolic rate, fasting, and negligible or negative growth. We hypothesized that winter dormancy is a survival strategy that arises in poleward species that tolerate severe, uncompensated constraints of cold on physiological performance. To date, we have measured the metabolic, exercise, and digestive performance of cunner (Tautogolabrus adspersus), a model winter-dormant fish, acclimated or acutely exposed to a wide range of temperatures (2-26°C). Contrary to our hypothesis, we found partial cold compensation of nearly all metabolic and exercise performance metrics studied, similar to winter-active species. Further, after bypassing the behavioural fasting response during dormancy using repeated force-feeding during cold acclimation, cunner were able to digest food and subsequently exhibit positive growth compared to negative growth of the voluntarily fasting fish. Only responsiveness to stimuli during the C-start escape response was greatly constrained in the cold even after acclimation, suggesting a thermal sensory limitation that may help explain the need to become dormant. To further explore this idea, we measured the C-start escape performance of six phylogenetically-diverse species along the spectrum of overwintering strategies from winter-dormant to winter-lethargic to winter-active. As we predicted, responsiveness was greater and more plastic in the winter-lethargic and -active species compared to -dormant species. While most physiological performance traits in cold dormant fish remain robust, impaired responsiveness to C-start stimuli may be a weak thermal link driving dormancy as an overwintering strategy among fishes.
12:10-12:30
Léger, A.¹², Aminot, M.¹², Jorissen, S.⁴, Hébert-Chatelain, E.²³, Pichaud, N.¹²
¹Department of Chemistry and Biochemistry, Université de Moncton, Moncton, NB, Canada; ²New Brunswick Centre for Precision Medicine, Moncton, NB, Canada; ³Department of Biology, Université de Moncton, Moncton, NB, Canada; ⁴Department of Biology, KU Leuven, Leuven, Belgium
The powerhouse of the hive: Seasonal differences in mitochondrial uncoupling, ATP and ROS production in honey bees
Because of their different roles within the hive, summer and winter honey bees (Apis mellifera) exhibit distinct phenotypes. We have recently demonstrated that honey bees’ mitochondria undergo drastic changes between seasons. More specifically, winter bees have lower CI-linked respiration but increased mtG3PDH- and CII-linked respiration. We hypothesize that this would lead to a decreased ATP production because mtG3PDH and CII do not directly contribute to proton pumping. Given the high energy requirements of winter bees, which shiver their thoracic muscles to keep the queen warm, we explored mechanisms allowing non-shivering thermogenesis that do not require ATP, specifically uncoupling proteins (UCP). Thus, in this study we investigated the seasonal differences in mitochondrial oxygen consumption, ATP production, site-specific reactive oxygen species (ROS) production and UCP activity in honey bees. Our results demonstrate that even though CI-linked respiration is diminished in winter bees, ATP production with CI substrates increased, suggesting that CI is more efficient in winter bees, likely to sustain shivering thermogenesis. On the other hand, succinate and G3P did not contribute to ATP production. Differences were also detected in terms of ROS production; overall, summer bees produced less ROS than all other seasons. Important UCP activity was detected in summer bees whereas winter bees displayed very little, or no UCP activity, suggesting that UCPs are not involved in thermogenesis in honey bees. However, increased UCP activity in the summer could help minimise ROS production, which might explain the low rates obtained in summer.
12:30-12:50
Van Wert, J. C.¹, Birnie-Gauvin, K.², Robinson, K. A.³, Patterson, D. A.³, Eliason, E. J.¹
¹Department of Ecology, Evolution & Marine Biology, University of California, Santa Barbara, CA 93106, USA; ²Section for Freshwater Fisheries and Ecology, National Institute of Aquatic Resources, Technical University of Denmark, Silkeborg, Denmark; ³Fisheries and Oceans Canada, Cooperative Resource Management Institute, School of Resource and Environmental Management, Simon Fraser University, Burnaby, BC V5A 1S6, Canada.
Heart function and pathology are linked to the migration success of Pacific salmon
The upstream spawning migration is a demanding feat for Pacific salmon (Oncorhynchus spp.). Relying on endogenous energy reserves, salmon often swim in warm water for weeks against strong currents and complex hydraulic conditions (e.g. rapids) to reach natal spawning grounds. Cardiac structure and function may determine migration outcomes. During migration, the heart’s excessive beating can damage the coronary artery, causing lesions that reduce oxygen supply to the compact myocardium (i.e., coronary arteriosclerosis). We sampled sockeye salmon (O. nerka) across various stages of their migration, including in the ocean, at the river entry, in a subset that failed part-way through migration, and at their spawning grounds, for signs of coronary arteriosclerosis and health status through blood chemistry. Coronary arteriosclerosis was most severe in fish that strayed and in fish sampled at the spawning grounds, occluding up to 25% of blood flow. We identified a suite of cardiorespiratory metrics associated with an unsuccessful migration. Fish that strayed showed signs of hyperkalemia (high plasma potassium levels, impairs heart contractility), advanced sexual maturity (relatively low plasma estradiol and testosterone concentrations), elevated plasma cardiac troponin C (indicative of O2 limitation to the heart), and less relative compact myocardium (reduced reliable oxygen supply to the heart). Our results underpin the importance of heart function in migration success. Its pathology, chemistry, and potential for a plastic morphological response may serve as an indicator of how hard the fish have worked and help describe and predict migration success.