Beneficial acclimation: sex specific thermal acclimation of metabolic capacity in the striped marsh frog (<i>Limnodynastes peronii</i>)

Considerable variation is inherent both within and between comparative physiological data sets. Known sources for such variation include diet, gender, time of day and season of experiment, among many other factors, but a meta-analysis of physiological studies shows that surprisingly few studies report controlling for these factors. In fact, less than 3% of comparative physiological papers mention epigenetics. However, our understanding of epigenetic influences on physiological processes is growing rapidly, and it is highly likely that epigenetic phenomena are an additional 'hidden' source of variation, particularly in wild-caught specimens. Recent studies have shown epigenetic inheritance of commonly studied traits such as metabolic rate (water fleas Daphnia magna; emu, Dromaius novaellandiae), hypoxic tolerance, cardiac performance (zebrafish, Danio rerio), as well as numerous morphological effects. The ecological and evolutionary significance of such epigenetic inheritance is discussed in a comparative physiological context. Finally, against this context of epigenetic inheritance of phenotype, this essay also provides a number of caveats and warnings regarding the interpretation of transgenerational phenotype modification as a true epigenetic phenomenon. Parental effects, sperm storage, multiple paternity and direct gamete exposure can all be confounding factors. Epigenetic inheritance may best be studied in animal models that can be maintained in the laboratory over multiple generations, to yield parental stock that themselves are free of epigenetic effects from the historical experiences of their parents.

Section: Sources Of Physiological Variation -The 'Usual Suspects'mentioning

confidence: 99%

Epigenetics as a source of variation in comparative animal physiology – or – Lamarck is lookin' pretty good these days

Burggren

2014

“…Lactate dehydrogenase is a glycolytic enzyme that converts pyruvate to lactic acid, thereby producing ATP rapidly in the absence of oxygen. All assays were conducted at 15 and 25°C according to published protocols (Rogers et al, 2007).…”

Section: Metabolic Enzyme Activitiesmentioning

confidence: 99%

Developmental thermal plasticity of prey modifies the impact of predation

Seebacher

Grigaltchik

2015

Self Cite

Environmental conditions during embryonic development can influence the mean expression of phenotypes as well as phenotypic responses to environmental change later in life. The resulting phenotypes may be better matched to their environment and more resilient to environmental change, including human-induced climate change. However, whether plasticity does improve success in an ecological context is unresolved. In a microcosm experiment, we show that developmental plasticity in embryos of the frog Limnodynastes peronii is beneficial by increasing survivorship of tadpoles in the presence of predators when egg incubation (15 or 25°C) and tadpole acclimation temperature in microcosms (15 or 25°C) coincided at 15°C. Tadpoles that survived predation were smaller, and had faster burst swimming speeds than those kept in no-predator control conditions, but only at high (25°C) egg incubation or subsequent microcosm temperatures. Metabolic rates were determined by a three-way interaction between incubation and microcosm temperatures and predation; maximal glycolytic and mitochondrial metabolic capacities (enzyme activities) were lower in survivors from predation compared with controls, particularly when eggs were incubated at 25°C. We show that thermal conditions experienced during early development are ecologically relevant by modulating survivorship from predation. Importantly, developmental thermal plasticity also impacts population phenotypes indirectly by modifying species interactions and the selection pressure imposed by predation.

“…For P. ridibundus and L. catesbeiana, mitochondrial oxygen consumption and membrane potential were assayed at 25°C. For R. temporaria, mitochondrial oxygen consumption and membrane potential were assayed at 20°C (values are from Salin et al, 2012b) and corresponding values were recalculated to 25°C assuming a Q 10 of 2.3 for oxygen consumption and of 1.05 for membrane potential (Berner, 1999;Chamberlin, 2004;Rogers et al, 2007;Trzcionka et al, 2008;Guderley and Seebacher, 2011). For all three species, the rates of mitochondrial proton leak were calculated at the highest common membrane potential value of 150 mV from the oxygen consumption rate by assuming a constant stoichiometry of six protons pumped (and leaked) per atom of oxygen for succinate.…”

Section: Mitochondrial Membrane Potentialmentioning

confidence: 99%

“…It is important to note that one previous study has reported a proton leak activity of around 30 nmol H + min −1 mg −1 protein in skeletal muscle mitochondria of common frog at 25°C (St-Pierre et al, 2000). Given that basal non-phosphorylating respiration rate and basal proton leak activity are on average 3.4-or 2.5-fold greater in skeletal muscle mitochondria than in liver mitochondria, respectively (St-Pierre et al, 2000;Hulbert et al, 2006;Rogers et al, 2007;Trzcionka et al, 2008;Guderley and Seebacher, 2011), the proton leak activity value of liver mitochondria from common frog should have ranged from 14 to 8.7 nmol H + min −1 mg −1 protein (at 150 mV and 25°C). Hence, in the present study, the calculated mean value of 9.7±1.2 nmol H + min −1 mg −1 protein (Fig.…”

Section: Mitochondrial Membrane Potentialmentioning

confidence: 99%

Oxidative phosphorylation efficiency, proton conductance and reactive oxygen species production of liver mitochondria correlates with body mass in frogs

Roussel

Salin

Dumet

et al. 2015

Body size is a central biological parameter affecting most biological processes (especially energetics) and the mitochondrion is a key organelle controlling metabolism and is also the cell's main source of chemical energy. However, the link between body size and mitochondrial function is still unclear, especially in ectotherms. In this study, we investigated several parameters of mitochondrial bioenergetics in the liver of three closely related species of frog (the common frog Rana temporaria, the marsh frog Pelophylax ridibundus and the bull frog Lithobates catesbeiana). These particular species were chosen because of their differences in adult body mass. We found that mitochondrial coupling efficiency was markedly increased with animal size, which led to a higher ATP production (+70%) in the larger frogs (L. catesbeiana) compared with the smaller frogs (R. temporaria). This was essentially driven by a strong negative dependence of mitochondrial proton conductance on body mass. Liver mitochondria from the larger frogs (L. catesbeiana) displayed 50% of the proton conductance of mitochondria from the smaller frogs (R. temporaria). Contrary to our prediction, the low mitochondrial proton conductance measured in L. catesbeiana was not associated with higher reactive oxygen species production. Instead, liver mitochondria from the larger individuals produced significantly lower levels of radical oxygen species than those from the smaller frogs. Collectively, the data show that key bioenergetics parameters of mitochondria (proton leak, ATP production efficiency and radical oxygen species production) are correlated with body mass in frogs. This research expands our understanding of the relationship between mitochondrial function and the evolution of allometric scaling in ectotherms.