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Anthony P. Farrell - One of the best experts on this subject based on the ideXlab platform.
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the Thermal acclimation potential of Maximum heart rate and cardiac heat tolerance in arctic char salvelinus alpinus a northern cold water specialist
2021Co-Authors: Matthew J H Gilbert, Anthony P. FarrellAbstract:Abstract Increasing heart rate (ƒH) is a central, if not primary mechanism used by fishes to support their elevated tissue oxygen consumption during acute warming. Thermal acclimation can adjust this acute response to improve cardiac performance and heat tolerance under the prevailing temperatures. We predict that such acclimation will be particularly important in regions undergoing rapid environmental change such as the Arctic. Therefore, we acclimated Arctic char (Salvelinus alpinus), a high latitude, cold-adapted salmonid, to ecologically relevant temperatures (2, 6, 10, 14 and 18 °C) and examined how Thermal acclimation influenced their cardiac heat tolerance by measuring the Maximum heart rate (ƒHmax) response to acute warming. As expected, acute warming increased ƒHmax in all Arctic char before ƒHmax reached a peak and then became arrhythmic. The peak ƒHmax, and the temperature at which peak ƒHmax (Tpeak) and that at which arrhythmia first occurred (Tarr) all increased progressively (+33%, 49% and 35%, respectively) with acclimation temperature from 2 to 14 °C. When compared at the same test temperature ƒHmax also decreased by as much as 29% with increasing acclimation temperature, indicating significant Thermal compensation. The upper temperature at which fish first lost their equilibrium (Critical Thermal Maximum: CTmax) also increased with acclimation temperature, albeit to a lesser extent (+11%). Importantly, Arctic char experienced mortality after several weeks of acclimation at 18 °C and survivors did not have elevated cardiac Thermal tolerance. Collectively, these findings suggest that if wild Arctic char have access to suitable temperatures (
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the effect of acute warming and Thermal acclimation on Maximum heart rate of the common killifish fundulus heteroclitus
2019Co-Authors: Hamid Safi, Yangfan Zhang, Patricia M Schulte, Anthony P. FarrellAbstract:Common killifish Fundulus heteroclitus were acclimated to ecologically relevant temperatures (5, 15 and 33°C) and their Maximum heart rate (fHmax ) was measured at each acclimation temperature during an acute warming protocol. Acclimation to 33°C increased peak fHmax by up to 32% and allowed the heart to beat rhythmically at a temperature 10°C higher when compared with acclimation to 5°C. Independent of acclimation temperature, peak fHmax occurred about 3°C cooler than the temperature that first produced cardiac arrhythmias. Thus, when compared with previously published values for the Critical Thermal Maximum of F. heteroclitus, the temperature for peak fHmax was cooler and the temperature that first produced cardiac arrhythmias was similar to these Critical Thermal maxima. The considerable Thermal plasticity of fHmax demonstrated in the present study is entirely consistent with euryThermal ecology of killifish, as shown previously for another euryThermal fish Gillichthys mirabilis.
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Cardiac mitochondrial metabolism may contribute to differences in Thermal tolerance of red- and white-blooded Antarctic notothenioid fishes.
2018Co-Authors: Kristin M. O'brien, Anthony P. Farrell, Anna S. Rix, Stuart Egginton, Elizabeth L. Crockett, Karen Schlauch, Rebekah Woolsey, Megan Hoffman, Sean MerrimanAbstract:Studies in temperate fishes provide evidence that cardiac mitochondrial function and the capacity to fuel cardiac work contribute to Thermal tolerance. Here, we tested the hypothesis that decreased cardiac aerobic metabolic capacity contributes to the lower Thermal tolerance of the haemoglobinless Antarctic icefish, Chaenocephalus aceratus, compared with that of the red-blooded Antarctic species, Notothenia coriiceps. Maximal activities of citrate synthase (CS) and lactate dehydrogenase (LDH), respiration rates of isolated mitochondria, adenylate levels and changes in mitochondrial protein expression were quantified from hearts of animals held at ambient temperature or exposed to their Critical Thermal Maximum (CTmax). Compared with C. aceratus, activity of CS, ATP concentration and energy charge were higher in hearts of N. coriiceps at ambient temperature and CTmax. While state 3 mitochondrial respiration rates were not impaired by exposure to CTmax in either species, state 4 rates, indicative of proton leakage, increased following exposure to CTmax in C. aceratus but not N. coriiceps. The interactive effect of temperature and species resulted in an increase in antioxidants and aerobic metabolic enzymes in N. coriiceps but not in C. aceratus. Together, our results support the hypothesis that the lower aerobic metabolic capacity of C. aceratus hearts contributes to its low Thermal tolerance.
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Mechanisms of Thermal adaptation and evolutionary potential of conspecific populations to changing environments
2018Co-Authors: Zhongqi Chen, Anthony P. Farrell, Amanda Matala, Shawn R NarumAbstract:: Heterogeneous and ever-changing Thermal environments drive the evolution of populations and species, especially when extreme conditions increase selection pressure for traits influencing fitness. However, projections of biological diversity under scenarios of climate change rarely consider evolutionary adaptive potential of natural species. In this study, we tested for mechanistic evidence of evolutionary Thermal adaptation among ecologically divergent redband trout populations (Oncorhynchus mykiss gairdneri) in cardiorespiratory function, cellular response and genomic variation. In a common garden environment, fish from an extreme desert climate had significantly higher Critical Thermal Maximum (p 3°C) than fish from cooler montane climate. In addition, the desert population had the highest Maximum heart rate during warming (20% greater than montane populations), indicating improved capacity to deliver oxygen to internal tissues. In response to acute heat stress, distinct sets of cardiac genes were induced among ecotypes, which helps to explain the differences in cardiorespiratory function. Candidate genomic markers and genes underlying these physiological adaptations were also pinpointed, such as genes involved in stress response and metabolic activity (hsp40, ldh-b and camkk2). These markers were developed into a multivariate model that not only accurately predicted Critical Thermal maxima, but also evolutionary limit of Thermal adaptation in these specific redband trout populations relative to the expected limit for the species. This study demonstrates mechanisms and limitations of an aquatic species to evolve under changing environments that can be incorporated into advanced models to predict ecological consequences of climate change for natural organisms.
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upper Thermal tolerance of wild type domesticated and growth hormone transgenic coho salmon oncorhynchus kisutch
2015Co-Authors: Zhongqi Chen, Robert H. Devlin, Anthony P. FarrellAbstract:In coho salmon Oncorhynchus kisutch, no significant differences in Critical Thermal Maximum (c. 26·9° C, CTmax ) were observed among size-matched wild-type, domesticated, growth hormone (GH)-transgenic fish fed to satiation, and GH-transgenic fish on a ration-restricted diet. Instead, GH-transgenic fish fed to satiation had significantly higher Maximum heart rate and Arrhenius breakpoint temperature (mean ± s.e. = 17·3 ± 0·1° C, TAB ). These results provide insight into effects of modified growth rate on temperature tolerance in salmonids, and can be used to assess the potential ecological consequences of GH-transgenic fishes should they enter natural environments with temperatures near their Thermal tolerance limits.
James D Kieffer - One of the best experts on this subject based on the ideXlab platform.
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the effects of repeat acute Thermal stress on the Critical Thermal Maximum ctmax and physiology of juvenile shortnose sturgeon acipenser brevirostrum
2019Co-Authors: Brittany Bard, James D KiefferAbstract:The shortnose sturgeon (Acipenser brevirostrum Lesueur, 1818) is a species of special concern in Canada, but little is known about their Thermal biology. Information on the upper Thermal tolerance ...
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the effects of dissolved oxygen and triploidy on Critical Thermal Maximum in brook charr salvelinus fontinalis
2013Co-Authors: Lauren E Ellis, Charles F D Sacobie, James D Kieffer, Tillmann J BenfeyAbstract:article i nfo This study examined the effect of dissolved oxygen (DO) level on Critical Thermal Maximum (CTMax) in diploid and triploid brook charr (Salvelinus fontinalis) exposed to a temperature increase of 3 °C/h. Because gas solubility is in- versely proportional to temperature, DO declines during standard CTMax tests. With this treatment as a baseline, oxygen or nitrogen injection was used to provide three other DO conditions during CTMax tests: two hyperoxic (maintenance at initial 10 mg/L and increase from 10 mg/L at 2 mg/L/h) and one hypoxic (decrease from 10 mg/L at 2 mg/L/h). Hyperoxia had no effect on temperature at CTMax or time taken to reach CTMax. Hypoxia, on the other hand, resulted in a significantly lower CTMax and shorter time to CTMax than under standard or hyperoxic conditions, with both indices affected by triploidy but not in a consistent fashion: in one experiment trip- loids had a lower CTMax and shorter time to CTMax than diploids and in a second experiment they had a higher CTMax and longer time to CTMax than diploids. Indices of the secondary stress response (plasma glucose and ions) during CTMax tests under hypoxia responded as would be predicted for an acute stress, with no difference between triploids and diploids.
Gamperla Kurt - One of the best experts on this subject based on the ideXlab platform.
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cardiorespiratory responses of seawater acclimated adult arctic char salvelinus alpinus and atlantic salmon salmo salar to an acute temperature increase
2014Co-Authors: M Penneychantelle, W Nashgordon, Gamperla KurtAbstract:In this first study examining the Thermal tolerance of adult Arctic char (Salvelinus alpinus) acclimated to seawater, we measured their Critical Thermal Maximum (CTMax) and several cardiorespiratory parameters (oxygen consumption (MO2), heart rate (fH), stroke volume (SV), cardiac output (Q), ventilatory frequency (VF), opercular pressure (PO), and ventilatory effort (VE)) when exposed to a temperature increase of 2 °C·h−1. Further, we directly compared these results with those obtained for the euryThermal Atlantic salmon (Salmo salar) under identical conditions. There was no significant difference in cardiorespiratory values between the two species at their acclimation temperature (9.5–10 °C). In contrast, the slope of the MO2–temperature relationship was lower (by 27%) in the char as compared with that in the salmon, and the char had significantly lower values for Maximum fH (by 13%), Maximum MO2 (by 35%), absolute metabolic scope (by 39%), and CTMax (approximately 23 versus 26.5 °C, respectively). Alth...
Bruce D. Sidell - One of the best experts on this subject based on the ideXlab platform.
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Thermal Tolerance of Antarctic Notothenioid Fishes Correlates with Level of Circulating Hemoglobin
2011Co-Authors: Jody M. Beers, Bruce D. SidellAbstract:AbstractThe West Antarctic Peninsula region is experiencing some of the most rapid elevations in temperature of any marine environment. We assessed Thermal tolerance of white- and red-blooded Antarctic notothenioid fishes inhabiting these waters, using a modified Critical Thermal Maximum (CTmax) design. Temperature was elevated acutely from ambient at a constant rate of 3.6°C h−1, and CTmax was defined as the temperature where animals lost righting response. CTmax temperatures of white-blooded icefishes Chionodraco rastrospinosus (C) and Chaenocephalus aceratus (C) were significantly lower than those of red-blooded fishes Gobionotothen gibberifrons (C) and Notothenia coriiceps (C). Lepidonotothen squamifrons, a red-blooded species with low hematocrit, exhibited a CTmax (C) that was significantly lower than that of the other red-blooded animals and similar to that of icefishes. A strong relationship between CTmax and hematocrit () suggests that the oxygen-carrying capacity of blood may partially dictate ac...
Sean Merriman - One of the best experts on this subject based on the ideXlab platform.
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Cardiac mitochondrial metabolism may contribute to differences in Thermal tolerance of red- and white-blooded Antarctic notothenioid fishes.
2018Co-Authors: Kristin M. O'brien, Anthony P. Farrell, Anna S. Rix, Stuart Egginton, Elizabeth L. Crockett, Karen Schlauch, Rebekah Woolsey, Megan Hoffman, Sean MerrimanAbstract:Studies in temperate fishes provide evidence that cardiac mitochondrial function and the capacity to fuel cardiac work contribute to Thermal tolerance. Here, we tested the hypothesis that decreased cardiac aerobic metabolic capacity contributes to the lower Thermal tolerance of the haemoglobinless Antarctic icefish, Chaenocephalus aceratus, compared with that of the red-blooded Antarctic species, Notothenia coriiceps. Maximal activities of citrate synthase (CS) and lactate dehydrogenase (LDH), respiration rates of isolated mitochondria, adenylate levels and changes in mitochondrial protein expression were quantified from hearts of animals held at ambient temperature or exposed to their Critical Thermal Maximum (CTmax). Compared with C. aceratus, activity of CS, ATP concentration and energy charge were higher in hearts of N. coriiceps at ambient temperature and CTmax. While state 3 mitochondrial respiration rates were not impaired by exposure to CTmax in either species, state 4 rates, indicative of proton leakage, increased following exposure to CTmax in C. aceratus but not N. coriiceps. The interactive effect of temperature and species resulted in an increase in antioxidants and aerobic metabolic enzymes in N. coriiceps but not in C. aceratus. Together, our results support the hypothesis that the lower aerobic metabolic capacity of C. aceratus hearts contributes to its low Thermal tolerance.
