| 1. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 2. |
- Egginton, S., et al.
(författare)
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Maximum cardiac performance of Antarctic fishes that lack haemoglobin and myoglobin: exploring the effect of warming on nature's natural knockouts
- 2019
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Ingår i: Conservation Physiology. - : Oxford University Press (OUP). - 2051-1434. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Antarctic notothenioids, some of which lack myoglobin (Mb) and/or haemoglobin (Hb), are considered extremely stenothermal, which raises conservation concerns since Polar regions are warming at unprecedented rates. Without reliable estimates of maximum cardiac output (((Q)over dot)), it is impossible to assess their physiological scope in response to warming seas. Therefore, we compared cardiac performance of two icefish species, Chionodraco rastrospinosus (Hb(-)Mb(+)) and Chaenocephalus aceratus (Hb(-)Mb(-)), with a related notothenioid, Notothenia coriiceps (Hb(+)Mb(+)) using an in situ perfused heart preparation. The maximum (Q)over dot, heart rate (f(H)), maximum cardiac work (WC) and relative ventricular mass of N. coriiceps at 1 degrees C were comparable to temperate-water teleosts, and acute warming to 4 degrees C increased fH and WC, as expected. In contrast, icefish hearts accommodated a higher maximum stroke volume (VS) and maximum. Q at 1 degrees C, but their unusually large hearts had a lower fH and maximum afterload tolerance than N. coriiceps at 1 degrees C. Furthermore, maximum VS, maximum. Q and fH were all significantly higher for the Hb(-)Mb(+) condition compared with the Hb(-)Mb(-) condition, a potential selective advantage when coping with environmental warming. Like N. coriiceps, both icefish species increased H-f at 4 degrees C. Acutely warming C. aceratus increased maximum (Q) over dot, while C. rastrospinosus (like N. coriiceps) held at 4 degrees C for 1 week maintained maximum. Q when tested at 4 degrees C. These experiments involving short-term warming should be followed up with long-term acclimation studies, since the maximum cardiac performance of these three Antarctic species studied seem to be tolerant of temperatures in excess of predictions associated with global warming.
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| 3. |
- Gilmour, Kathleen M., et al.
(författare)
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Through the looking glass : attempting to predict future opportunities and challenges in experimental biology
- 2023
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Ingår i: The Journal of experimental biology. - 1477-9145. ; 226:24
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Tidskriftsartikel (refereegranskat)abstract
- To celebrate its centenary year, Journal of Experimental Biology (JEB) commissioned a collection of articles examining the past, present and future of experimental biology. This Commentary closes the collection by considering the important research opportunities and challenges that await us in the future. We expect that researchers will harness the power of technological advances, such as '-omics' and gene editing, to probe resistance and resilience to environmental change as well as other organismal responses. The capacity to handle large data sets will allow high-resolution data to be collected for individual animals and to understand population, species and community responses. The availability of large data sets will also place greater emphasis on approaches such as modeling and simulations. Finally, the increasing sophistication of biologgers will allow more comprehensive data to be collected for individual animals in the wild. Collectively, these approaches will provide an unprecedented understanding of 'how animals work' as well as keys to safeguarding animals at a time when anthropogenic activities are degrading the natural environment.
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| 4. |
- Joyce, W., et al.
(författare)
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Adrenergic and adenosinergic regulation of the cardiovascular system in an Antarctic icefish: Insight into central and peripheral determinants of cardiac output
- 2019
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Ingår i: Comparative Biochemistry and Physiology a-Molecular & Integrative Physiology. - : Elsevier BV. - 1095-6433. ; 230, s. 28-38
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Tidskriftsartikel (refereegranskat)abstract
- Icefishes characteristically lack the oxygen-binding protein haemoglobin and therefore are especially reliant on cardiovascular regulation to augment oxygen transport when oxygen demand increases, such as during activity and warming. Using both in vivo and in vitro experiments, we evaluated the roles for adrenaline and adenosine, two well-established cardio- and vasoactive molecules, in regulating the cardiovascular system of the blackfin icefish, Chaenocephalus aceratus. Despite increasing cardiac contractility (increasing twitch force and contraction kinetics in isometric myocardial strip preparations) and accelerating heart rate (f(H)), adrenaline (5 nmol kg(-1) bolus infra-arterial injection) did not significantly increase cardiac output ((Q) over dot) in vivo because it elicited a large decrease in vascular conductance (G(sys)). In contrast, and despite preliminary data suggesting a direct negative inotropic effect of adenosine on isolated atria and little effect on isolated ventricle strips, adenosine (500 nmol kg-1) generated a large increase in (Q) over dot by increasing G(sys), a change reminiscent of that previously reported during both acute warming and invoked activity. Our data thus illustrate how (Q) over dot in C. aceratus may be much more dependent on peripheral control of vasomotor tone than direct regulation of the heart.
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| 5. |
- Joyce, W., et al.
(författare)
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Exploring nature's natural knockouts: in vivo cardiorespiratory performance of Antarctic fishes during acute warming
- 2018
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 221:15
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Tidskriftsartikel (refereegranskat)abstract
- We tested the hypothesis that blackfin icefish (Chaenocephalus aceratus), one of the six species in the family Channichthyidae (the icefishes) that do not express haemoglobin and myoglobin, lack regulatory cardiovascular flexibility during acute warming and activity. The experimental protocols were designed to optimize the surgical protocol and minimize stress. First, minimally invasive heart rate (f(H)) measurements were made during a thermal ramp until cardiac failure in C. aceratus and compared with those from the closely related red-blooded black rockcod (Notothenia coriiceps). Then, integrative cardiovascular adjustments were more extensively studied using flow probes and intravascular catheters in C. aceratus during acute warming (from 0 to 8 degrees C) at rest and after imposed activity. Chaenocephalus aceratus had a lower routine f H than N. coriiceps (9 beats min(-1) versus 14 beats min(-1)) and a lower peak f(H )during acute warming (38 beats min' versus 55 beats min(-1)) with a similar cardiac breakpoint temperature (13 and 14 degrees C, respectively). Routine cardiac output ((Q) over dot) for C. aceratus at similar to 0 degrees C was much lower (26.6 ml min(-1) kg(-1)) than previously reported, probably because fish in the present study had a low f(H) (12 beats min(-1)) indicative of a high routine vagal tone and low stress. Chaenocephalus aceratus increased oxygen consumption during acute warming and with activity. Correspondingly, (Q) over dot increased considerably (maximally 86.3 ml min(-1) kg(-1)), as did vascular conductance (5-fold). Thus, unlike earlier suggestions, these data provide convincing evidence that icefish can mount a well-developed cardiovascular regulation of heart rate, cardiac output and vascular conductance, and this regulatory capacity provides flexibility during acute warming.
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| 6. |
- Joyce, W., et al.
(författare)
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The effects of thermal acclimation on cardio-respiratory performance in an Antarctic fish (Notothenia coriiceps)
- 2018
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Ingår i: Conservation Physiology. - : Oxford University Press (OUP). - 2051-1434. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The Southern Ocean has experienced stable, cold temperatures for over 10 million years, yet particular regions are currently undergoing rapid warming. To investigate the impacts of warming on cardiovascular oxygen transport, we compared the cardio-respiratory performance in an Antarctic notothenioid (Notothenia coriiceps) that was maintained at 0 or 5 degrees C for 6.0-9.5 weeks. When compared at the fish's respective acclimation temperature, the oxygen consumption rate and cardiac output were significantly higher in 5 degrees C-acclimated than 0 degrees C-acclimated fish. The 2.7-fold elevation in cardiac output in 5 degrees C-acclimated fish (17.4 vs. 6.5 ml min(-1) kg(-1)) was predominantly due to a doubling of stroke volume, likely in response to increased cardiac preload, as measured by higher central venous pressure (0.15 vs. 0.08 kPa); tachycardia was minor (295 vs. 25.2 beats min(-1)). When fish were acutely warmed, oxygen consumption rate increased by similar amounts in 0 degrees C- and 5 degrees C-acclimated fish at equivalent test temperatures. In both acclimation groups, the increases in oxygen consumption rate during acute heating were supported by increased cardiac output achieved by elevating heart rate, while stroke volume changed relatively little. Cardiac output was similar between both acclimation groups until 12 degrees C when cardiac output became significantly higher in 5 degrees C-acclimated fish, driven largely by their higher stroke volume. Although cardiac arrhythmias developed at a similar temperature (similar to 14.5 degrees C) in both acclimation groups, the hearts of 5 degrees C-acclimated fish continued to pump until significantly higher temperatures (CTmax for cardiac function 17.7 vs. 15.0 degrees C for 0 degrees C-acclimated fish). These results demonstrate that N. coriiceps is capable of increasing routine cardiac output during both acute and chronic warming, although the mechanisms are different (heart rate-dependent versus primarily stroke volume-dependent regulation, respectively). Cardiac performance was enhanced at higher temperatures following 5 degrees C acclimation, suggesting cardiovascular function may not constrain the capacity of N. coriiceps to withstand a warming climate.
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| 7. |
- O'Brien, K. M., et al.
(författare)
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Resilience of cardiac performance in Antarctic notothenioid fishes in a warming climate
- 2021
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 224:10
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Tidskriftsartikel (refereegranskat)abstract
- Warming in the region of the Western Antarctic Peninsula is occurring at an unprecedented rate, which may threaten the survival of Antarctic notothenioid fishes. Herein, we review studies characterizing thermal tolerance and cardiac performance in notothenioids - a group that includes both red-blooded species and the white-blooded, haemoglobinless icefishes - as well as the relevant biochemistry associated with cardiac failure during an acute temperature ramp. Because icefishes do not feed in captivity, making long-term acclimation studies unfeasible, we focus only on the responses of red-blooded notothenioids to warm acclimation. With acute warming, hearts of the white-blooded icefish Chaenocephalus aceratus display persistent arrhythmia at a lower temperature (8 degrees C) compared with those of the red-blooded Notothenia coriiceps (14 degrees C). When compared with the icefish, the enhanced cardiac performance of N. coriiceps during warming is associated with greater aerobic capacity, higher ATP levels, less oxidative damage and enhanced membrane integrity. Cardiac performance can be improved in N. coriiceps with warm acclimation to 5 degrees C for 6-9 weeks, accompanied by an increase in the temperature at which cardiac failure occurs. Also, both cardiac mitochondrial and microsomal membranes are remodelled in response to warm acclimation in N. coriiceps, displaying homeoviscous adaptation. Overall, cardiac performance in N. coriiceps is malleable and resilient to warming, yet thermal tolerance and plasticity vary among different species of notothenioid fishes; disruptions to the Antarctic ecosystem driven by climate warming and other anthropogenic activities endanger the survival of notothenioids, warranting greater protection afforded by an expansion of marine protected areas.
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