Absence of mitochondrial responses in muscles of zebrafish exposed to several heat waves

An evolving roadmap: using mitochondrial physiology to help guide conservation efforts

The crucial role of aerobic energy production in sustaining eukaryotic life positions mitochondrial processes as key determinants of an animal's ability to withstand unpredictable environments. The advent of new techniques facilitating the measurement of mitochondrial function offers an increasingly promising tool for conservation approaches. Herein, we synthesize the current knowledge on the links between mitochondrial bioenergetics, ecophysiology and local adaptation, expanding them to the wider conservation physiology field. We discuss recent findings linking cellular bioenergetics to whole-animal fitness, in the current context of climate change. We summarize topics, questions, methods, pitfalls and caveats to help provide a comprehensive roadmap for studying mitochondria from a conservation perspective. Our overall aim is to help guide conservation in natural populations, outlining the methods and techniques that could be most useful to assess mitochondrial function in the field.

Non-lethal sampling for assessment of mitochondrial function does not affect metabolic rate and swimming performance

A fundamental issue in the metabolic field is whether it is possible to understand underlying mechanisms that characterize individual variation. Whole-animal performance relies on mitochondrial function as it produces energy for cellular processes. However, our lack of longitudinal measures to evaluate how mitochondrial function can change within and among individuals and with environmental context makes it difficult to assess individual variation in mitochondrial traits. The aims of this study were to test the repeatability of muscle mitochondrial metabolism by performing two biopsies of red muscle, and to evaluate the effects of biopsies on whole-animal performance in goldfish Carassius auratus. Our results show that basal mitochondrial respiration and net phosphorylation efficiency are repeatable at 14-day intervals. We also show that swimming performance (optimal cost of transport and critical swimming speed) was repeatable in biopsied fish, whereas the repeatability of individual oxygen consumption (standard and maximal metabolic rates) seemed unstable over time. However, we noted that the means of individual and mitochondrial traits did not change over time in biopsied fish. This study shows that muscle biopsies allow the measurement of mitochondrial metabolism without sacrificing animals and that two muscle biopsies 14 days apart affect the intraspecific variation in fish performance without affecting average performance of individuals. This article is part of the theme issue 'The evolutionary significance of variation in metabolic rates'.

Global warming and nanoplastic toxicity; small temperature increases can make gill and liver toxicity more dramatic, which affects fillet quality caused by polystyrene nanoplastics in the adult zebrafish model

Increasing nanoplastics (NPs) pollution may lead to unknown environmental risks when considered together with climate change, which has the potential to become an increasingly important environmental issue in the coming decades. In this context, the present study aimed to evaluate the stressor modelling of polystyrene nanoplastic (PS-NPs) combined with temperature increase in zebrafish. For this purpose, changes in gill, liver and muscle tissues of zebrafish exposed to PS-NPs (25 ppm) and/or different temperatures (28, 29 and 30 °C) for 96 h under static conditions were evaluated. The results obtained emphasize that exposure to PS-NPs stressors under controlled conditions with temperature increase induces DNA damage through stress-induced responses accompanied by degeneration, necrosis and hyperaemia in zebrafish liver and adhesion of lamellae, desquamation and inflammation in lamellar epithelium in gills. Metabolomic analyses also supported changes indicating protein and lipid oxidation, especially PS-NPs-mediated. These findings will contribute to the literature as key data on the effects of PS-NPs presence on protein/lipid oxidation and fillet quality in muscle tissues.