Wednesday/Mercredi, May/Mai 8
11:00-13:00
President’s Award/Prix du Président
Postdoc Talks/Présentations postdocs
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
Lebenzon, J.E., Diaz, T., Williams, C.M.
Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA
Break it ‘til you make it: Selective flight muscle histolysis in the California variable field cricket
Many animals have evolved the capacity to remodel their muscle to match varying energetic demands of their life cycle. Skeletal muscles are key to locomotor performance and dispersal, making the ability to grow and maintain this muscle crucial for increasing organismal fitness. However, maintaining, and using skeletal muscle is energetically expensive. In insects, the energetic costs of their skeletal-like flight muscles lead to resource-based trade-offs that limit early life reproductive investment. When the costs of using and maintaining flight muscle outweigh the potential dispersal benefits, many insects can selectively break down (histolyse) their flight muscle to reallocate those resources towards reproduction. California variable field crickets (Gryllus lineaticeps) histolyse their flight muscle in this flight for reproduction trade-off, which results in the selective breakdown of one set of flight muscles (dorsolongitudinal; DLM) and maintenance of the neighbouring dorsoventral muscle (DVM). Despite the importance of flight muscle histolysis on cricket reproduction, we have a limited understanding of the mechanisms underlying the massive cellular re-organization required for this histolysis. Here, our objectives were to understand the structural and functional changes associated with muscle histolysis, explore how crickets integrate upstream signals into downstream selective remodeling of DLM and maintenance of DVM, and use RNAi to establish causal links between candidate regulatory pathways and selective flight muscle histolysis. The ability to selectively degrade a single muscle type is unique to insects, thus understanding the mechanisms underlying flight muscle histolysis can contribute to a broader understanding of how muscle plasticity has evolved to combat energetic challenges.
11:30-11:50
Weinrauch, A.M., Bouyoucos, I.A., Anderson, W.G.
Department of Biology, University of Manitoba, Winnipeg, MB, Canada
Identification of alternate stress hormone production in elasmobranchs
The stress response is highly conserved across vertebrates with the corticosteroids cortisol and corticosterone mediating this response. Elasmobranchs have a unique corticosteroid, 1α-hydroxycorticosterone (1α-OH-B) and were previously not thought to produce cortisol. The complete biosynthetic pathway for 1α-OH-B is unknown but is hypothesized to involve symbiotic bacteria in the steroidogenic interrenal tissue, that are known to metabolize steroids including cortisol. Thus, we predicted that reducing the microbial population could elicit increased circulation of cortisol. First, sequencing the Pacific spiny dogfish (Squalus suckleyi) interrenal transcriptome verified the presence of 17α-hydroxylase (cyp17a), an enzyme necessary to produce steroid precursors of cortisol. Next, dogfish were exposed to either low salinity (21 ppt) or antibiotics, both of which have been shown to reduce microbial activity in S. suckleyi. Cortisol was not detected in plasma prior to low salinity exposure; however, following exposure, cortisol reached detectable levels in every dogfish. Further, transcripts of some steroidogenic enzymes upregulated during low salinity. Antibiotic exposure increased the number of dogfish with detectable cortisol (81%) compared to gavaged controls (38%). To investigate physiological actions of cortisol, cortisol was implanted and blood was collected over 72h. Cortisol implantation decreased corticosterone (indicative of negative feedback) and glucose concentrations, suggestive of a putative glucocorticoid effect. Overall, we demonstrate that despite the decades-long belief of an absence of cortisol, S. suckleyi do produce cortisol in a context-dependent manner, and that cortisol has putative glucocorticoid actions in this elasmobranch. These data have implications for understanding endocrine control of mineral and energy balance in elasmobranchs.
11:50-12:10
Thompson A.¹, Masood N.¹, Easwaramoorthy M.¹, Hartenstein P.², Laframboise L.¹, Chow E.³, Choh V.³, McCulloch D.³, Manzon R.², Somers C.², and Wilson J.Y.¹
¹Department of Biology, McMaster University, Hamilton, Canada; ²Department of Biology, University of Regina, Regina, Canada; ³School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada
Increased rearing temperature delays the development of the thyroid, alters eye development and impairs its function, and perturbs ecologically relevant behaviours of the yellow perch (Perca flavescens)
Due to anthropogenic impacts, water temperatures are projected to rise by nearly 3°C over the coming decades. Elevations in temperature may be of concern for the yellow perch (Perca flavescens), a cool-water fish of great cultural and economic importance. We have previously determined that small elevations in temperature can alter growth rates, morphology, and the metabolism of larval yellow perch. Suspecting endocrine disruption, we tested the hypothesis that elevations in temperature dysregulate the thyroid system in developing perch. We reared yellow perch at 12, 15 (optimal), and 18°C during embryogenesis, with hatched fish raised at common garden conditions (18°C). Antibody staining revealed that thyroid follicles first appear 1 day post-hatch (DPH) in fish reared at 12 and 15°C but are only first seen at 4 DPH in fish reared at 18°C, with molecular investigations into genes such as slc5a5 (iodide transporter), and dio3 (thyroid hormone inactivating enzyme) supporting these observations. As the thyroid system has been linked to the development of the eye, we investigated eye growth, discovering that the eyes of 18°C fish are larger. Using electroretinograms, we show that increased rearing temperature leads to higher responses of the eye to light. A novel light behavioural test demonstrated that yellow perch larvae reared at elevated temperatures (18°C) cannot discern differences in low levels of light. When presented with a foraging challenge, increased temperature during rearing leads to reductions in prey consumption of larval yellow perch (12°C=15°C>18°C). Together, the results generated in this study suggest that yellow perch are sensitive to increases in temperature, a concern for a species that has experienced significant population declines.
12:10-12:30
Cieri, R.L.
Department of Zoology, University of British Columbia
Adaptations for huge body size and extreme ventilatory mechanics in cetacean pulmonary airway morphology and flow patterns
The pulmonary systems of Cetaceans are the largest in evolutionary history and tell a fascinating story about adaptation to marine life. Biomechanical challenges to lung design in cetaceans include not only extreme body size, but the repeated collapse and reinflation of lungs due to external pressure during diving, and extreme ventilatory dynamics due to exceptionally short breaths and high tidal volumes - approaching 90% of total lung capacity during short surface bouts. Using morphological analysis of pulmonary airways segmented from computed tomography (CT) scans of inflated lungs from 13 species, we show that airway morphology differs substantially from terrestrial mammals and varies substantially among cetacean species.
One main finding is that the conducting airways in deep-diving, slow-ventilating beaked whales (Ziphiidae) are relatively larger than those in shallow-diving, fast-ventilating dolphins (Delphinidae), suggesting that the need to store lung gas in the primary airways during lung collapse during diving may be a more important driving factor in airway design than maximizing pulmonary flow rates. By using computational fluid dynamics simulations built using one-dimensional tree-growing algorithms to extend the pulmonary tree down to the pulmonary acini, we show that branching angles and diameter ratios evolved to enable extremely fast and short ventilation in cetaceans. By combining our airway sophisticated models with traditional measurements and LiDAR/photogrammetry models of lung anatomy from species which are too large to CT scan, we can perform an allometric analysis of airway shape and size in cetaceans and simulate how breathing works in the largest lungs of all time.
12:30-12:50
Kong, J.D., Muzzatti, M.J., Vadboncoeur, É., Bertram, S. M., MacMillan, H.A.
Department of Biology, Carleton University, Ottawa, Canada
Effects of diet and temperature on cricket performance
Insects are reared en masse for releases related to conservation or pest management, for food and feed production and waste processing, as well as important services like pollination, decomposition, and disease control. Physiological performance fundamentally underpins the quantities and qualities of insects necessary for success in mass rearing programs. Such characteristics include growth, development and survival that, in turn, are modulated by extrinsic factors such as temperature and diet. However the relationships between these factors and how they modulate performance deficits and gains at the scale of a mass rearing operation are poorly understood. Here, I showcase how rearing temperature and diet affects the performance of farmed crickets (Gryllodes sigillatus) through trade offs in growth, development and survival. Higher rearing temperatures (30-38°C) resulted in rapidly maturing and larger crickets at the expense of lower survival and shorter lifespans compared with lower rearing temperatures (20-28°C). Group reared crickets reared on higher protein diets did not differ in growth and development metrics but had lower survival than control diets, and these patterns contrasted with individually reared crickets. I discuss how manipulating insect physiology through rearing conditions and context can ensure the continued success and optimisation of mass rearing programs and the services they provide.
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
Lebenzon, J.E., Diaz, T., Williams, C.M.
Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA
Break it ‘til you make it: Selective flight muscle histolysis in the California variable field cricket
Many animals have evolved the capacity to remodel their muscle to match varying energetic demands of their life cycle. Skeletal muscles are key to locomotor performance and dispersal, making the ability to grow and maintain this muscle crucial for increasing organismal fitness. However, maintaining, and using skeletal muscle is energetically expensive. In insects, the energetic costs of their skeletal-like flight muscles lead to resource-based trade-offs that limit early life reproductive investment. When the costs of using and maintaining flight muscle outweigh the potential dispersal benefits, many insects can selectively break down (histolyse) their flight muscle to reallocate those resources towards reproduction. California variable field crickets (Gryllus lineaticeps) histolyse their flight muscle in this flight for reproduction trade-off, which results in the selective breakdown of one set of flight muscles (dorsolongitudinal; DLM) and maintenance of the neighbouring dorsoventral muscle (DVM). Despite the importance of flight muscle histolysis on cricket reproduction, we have a limited understanding of the mechanisms underlying the massive cellular re-organization required for this histolysis. Here, our objectives were to understand the structural and functional changes associated with muscle histolysis, explore how crickets integrate upstream signals into downstream selective remodeling of DLM and maintenance of DVM, and use RNAi to establish causal links between candidate regulatory pathways and selective flight muscle histolysis. The ability to selectively degrade a single muscle type is unique to insects, thus understanding the mechanisms underlying flight muscle histolysis can contribute to a broader understanding of how muscle plasticity has evolved to combat energetic challenges.
11:30-11:50
Weinrauch, A.M., Bouyoucos, I.A., Anderson, W.G.
Department of Biology, University of Manitoba, Winnipeg, MB, Canada
Identification of alternate stress hormone production in elasmobranchs
The stress response is highly conserved across vertebrates with the corticosteroids cortisol and corticosterone mediating this response. Elasmobranchs have a unique corticosteroid, 1α-hydroxycorticosterone (1α-OH-B) and were previously not thought to produce cortisol. The complete biosynthetic pathway for 1α-OH-B is unknown but is hypothesized to involve symbiotic bacteria in the steroidogenic interrenal tissue, that are known to metabolize steroids including cortisol. Thus, we predicted that reducing the microbial population could elicit increased circulation of cortisol. First, sequencing the Pacific spiny dogfish (Squalus suckleyi) interrenal transcriptome verified the presence of 17α-hydroxylase (cyp17a), an enzyme necessary to produce steroid precursors of cortisol. Next, dogfish were exposed to either low salinity (21 ppt) or antibiotics, both of which have been shown to reduce microbial activity in S. suckleyi. Cortisol was not detected in plasma prior to low salinity exposure; however, following exposure, cortisol reached detectable levels in every dogfish. Further, transcripts of some steroidogenic enzymes upregulated during low salinity. Antibiotic exposure increased the number of dogfish with detectable cortisol (81%) compared to gavaged controls (38%). To investigate physiological actions of cortisol, cortisol was implanted and blood was collected over 72h. Cortisol implantation decreased corticosterone (indicative of negative feedback) and glucose concentrations, suggestive of a putative glucocorticoid effect. Overall, we demonstrate that despite the decades-long belief of an absence of cortisol, S. suckleyi do produce cortisol in a context-dependent manner, and that cortisol has putative glucocorticoid actions in this elasmobranch. These data have implications for understanding endocrine control of mineral and energy balance in elasmobranchs.
11:50-12:10
Thompson A.¹, Masood N.¹, Easwaramoorthy M.¹, Hartenstein P.², Laframboise L.¹, Chow E.³, Choh V.³, McCulloch D.³, Manzon R.², Somers C.², and Wilson J.Y.¹
¹Department of Biology, McMaster University, Hamilton, Canada; ²Department of Biology, University of Regina, Regina, Canada; ³School of Optometry and Vision Science, University of Waterloo, Waterloo, Canada
Increased rearing temperature delays the development of the thyroid, alters eye development and impairs its function, and perturbs ecologically relevant behaviours of the yellow perch (Perca flavescens)
Due to anthropogenic impacts, water temperatures are projected to rise by nearly 3°C over the coming decades. Elevations in temperature may be of concern for the yellow perch (Perca flavescens), a cool-water fish of great cultural and economic importance. We have previously determined that small elevations in temperature can alter growth rates, morphology, and the metabolism of larval yellow perch. Suspecting endocrine disruption, we tested the hypothesis that elevations in temperature dysregulate the thyroid system in developing perch. We reared yellow perch at 12, 15 (optimal), and 18°C during embryogenesis, with hatched fish raised at common garden conditions (18°C). Antibody staining revealed that thyroid follicles first appear 1 day post-hatch (DPH) in fish reared at 12 and 15°C but are only first seen at 4 DPH in fish reared at 18°C, with molecular investigations into genes such as slc5a5 (iodide transporter), and dio3 (thyroid hormone inactivating enzyme) supporting these observations. As the thyroid system has been linked to the development of the eye, we investigated eye growth, discovering that the eyes of 18°C fish are larger. Using electroretinograms, we show that increased rearing temperature leads to higher responses of the eye to light. A novel light behavioural test demonstrated that yellow perch larvae reared at elevated temperatures (18°C) cannot discern differences in low levels of light. When presented with a foraging challenge, increased temperature during rearing leads to reductions in prey consumption of larval yellow perch (12°C=15°C>18°C). Together, the results generated in this study suggest that yellow perch are sensitive to increases in temperature, a concern for a species that has experienced significant population declines.
12:10-12:30
Cieri, R.L.
Department of Zoology, University of British Columbia
Adaptations for huge body size and extreme ventilatory mechanics in cetacean pulmonary airway morphology and flow patterns
The pulmonary systems of Cetaceans are the largest in evolutionary history and tell a fascinating story about adaptation to marine life. Biomechanical challenges to lung design in cetaceans include not only extreme body size, but the repeated collapse and reinflation of lungs due to external pressure during diving, and extreme ventilatory dynamics due to exceptionally short breaths and high tidal volumes - approaching 90% of total lung capacity during short surface bouts. Using morphological analysis of pulmonary airways segmented from computed tomography (CT) scans of inflated lungs from 13 species, we show that airway morphology differs substantially from terrestrial mammals and varies substantially among cetacean species.
One main finding is that the conducting airways in deep-diving, slow-ventilating beaked whales (Ziphiidae) are relatively larger than those in shallow-diving, fast-ventilating dolphins (Delphinidae), suggesting that the need to store lung gas in the primary airways during lung collapse during diving may be a more important driving factor in airway design than maximizing pulmonary flow rates. By using computational fluid dynamics simulations built using one-dimensional tree-growing algorithms to extend the pulmonary tree down to the pulmonary acini, we show that branching angles and diameter ratios evolved to enable extremely fast and short ventilation in cetaceans. By combining our airway sophisticated models with traditional measurements and LiDAR/photogrammetry models of lung anatomy from species which are too large to CT scan, we can perform an allometric analysis of airway shape and size in cetaceans and simulate how breathing works in the largest lungs of all time.
12:30-12:50
Kong, J.D., Muzzatti, M.J., Vadboncoeur, É., Bertram, S. M., MacMillan, H.A.
Department of Biology, Carleton University, Ottawa, Canada
Effects of diet and temperature on cricket performance
Insects are reared en masse for releases related to conservation or pest management, for food and feed production and waste processing, as well as important services like pollination, decomposition, and disease control. Physiological performance fundamentally underpins the quantities and qualities of insects necessary for success in mass rearing programs. Such characteristics include growth, development and survival that, in turn, are modulated by extrinsic factors such as temperature and diet. However the relationships between these factors and how they modulate performance deficits and gains at the scale of a mass rearing operation are poorly understood. Here, I showcase how rearing temperature and diet affects the performance of farmed crickets (Gryllodes sigillatus) through trade offs in growth, development and survival. Higher rearing temperatures (30-38°C) resulted in rapidly maturing and larger crickets at the expense of lower survival and shorter lifespans compared with lower rearing temperatures (20-28°C). Group reared crickets reared on higher protein diets did not differ in growth and development metrics but had lower survival than control diets, and these patterns contrasted with individually reared crickets. I discuss how manipulating insect physiology through rearing conditions and context can ensure the continued success and optimisation of mass rearing programs and the services they provide.