关键词: Mnt1 TOR hypoxia metabolic performance rictorΔ2 thermal limits

Mesh : Female Male Animals Drosophila melanogaster / genetics Thermotolerance Cell Size Mutation Hypoxia / genetics Oxygen

来  源:   DOI:10.1098/rstb.2022.0490   PDF(Pubmed)

Abstract:
Understanding metabolic performance limitations is key to explaining the past, present and future of life. We investigated whether heat tolerance in actively flying Drosophila melanogaster is modified by individual differences in cell size and the amount of oxygen in the environment. We used two mutants with loss-of-function mutations in cell size control associated with the target of rapamycin (TOR)/insulin pathways, showing reduced (mutant rictorΔ2) or increased (mutant Mnt1) cell size in different body tissues compared to controls. Flies were exposed to a steady increase in temperature under normoxia and hypoxia until they collapsed. The upper critical temperature decreased in response to each mutation type as well as under hypoxia. Females, which have larger cells than males, had lower heat tolerance than males. Altogether, mutations in cell cycle control pathways, differences in cell size and differences in oxygen availability affected heat tolerance, but existing theories on the roles of cell size and tissue oxygenation in metabolic performance can only partially explain our results. A better understanding of how the cellular composition of the body affects metabolism may depend on the development of research models that help separate various interfering physiological parameters from the exclusive influence of cell size. This article is part of the theme issue \'The evolutionary significance of variation in metabolic rates\'.
摘要:
了解代谢表现的局限性是解释过去的关键,生活的现在和未来。我们调查了活跃飞行的果蝇的耐热性是否因细胞大小和环境中氧气量的个体差异而受到影响。我们在与雷帕霉素(TOR)/胰岛素途径相关的细胞大小控制中使用了两种功能丧失突变的突变体,与对照相比,在不同的身体组织中显示出减少的(突变型rictorΔ2)或增加的(突变型Mnt1)细胞大小。苍蝇在常氧和缺氧下暴露于温度的稳定升高,直到它们崩溃。响应于每种突变类型以及在缺氧条件下,最高临界温度降低。雌性,它们的细胞比雄性大,耐热性低于男性。总之,细胞周期控制途径中的突变,细胞大小的差异和氧气可用性的差异影响耐热性,但是关于细胞大小和组织氧合在代谢表现中的作用的现有理论只能部分解释我们的结果。对身体细胞组成如何影响新陈代谢的更好理解可能取决于研究模型的发展,这些模型有助于将各种干扰生理参数与细胞大小的专有影响分开。本文是“代谢率变化的进化意义”主题的一部分。
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