Evaluating the impacts of anthropogenic disturbance on free-ranging marine mammal populations, many of which are in decline, requires robust diagnostic markers of physiological stress and health. However, circulating levels of canonical 'stress hormones' such as glucocorticoids, which are commonly used to evaluate animal health, do not capture the complexity of species-specific responses and cannot be easily measured in large, fully aquatic marine mammals. Alternatively, expression of stress-responsive genes in hormone target tissues such as blubber, the specialized subcutaneous adipose tissue that can be manually or remotely sampled from many marine mammals, may be a more informative and sensitive indicator of recent (within 24 h) exposure to stressors. We previously identified genes that were upregulated in the inner blubber of juvenile northern elephant seals during experimental stimulation of the hypothalamic-pituitary-adrenal axis. In this study, we measured baseline expression levels of a subset of these genes in inner blubber of unmanipulated juvenile elephant seals of varying physiological states and correlated them with other stress markers (body condition index, corticosteroid and thyroid hormone levels). Expression of 10 genes, including those associated with lipid metabolism (ACSL1, HMGCS2, CDO1), redox homeostasis (GPX3), adipokine signaling (ADIPOQ), lipid droplet formation (PLIN1, CIDEA) and adipogenesis (DKK1, AZGP1, TGFBI), was described by three principal components and was associated with cortisol and thyroid hormone levels. Significantly, baseline gene expression levels were predictive of circulating hormone levels, suggesting that these markers may be potential indicators of exposure to stressors in marine mammal species that are inaccessible for blood sampling. A similar approach may be used to identify species-specific stress markers in other tissues that can be sampled by remote biopsy dart from free-ranging marine mammals, such as outer blubber and skin.

中文翻译：

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用于评估海洋哺乳动物应激的鲸脂基因表达指数。


评估人为干扰对自由放养的海洋哺乳动物种群的影响（其中许多海洋哺乳动物种群数量正在减少）需要强有力的生理压力和健康诊断标记。然而，通常用于评估动物健康的典型“应激激素”（例如糖皮质激素）的循环水平并不能反映物种特异性反应的复杂性，并且无法在大型全水生海洋哺乳动物中轻松测量。或者，激素靶组织（例如鲸脂，一种可以从许多海洋哺乳动物中手动或远程采集的特殊皮下脂肪组织）中应激反应基因的表达，可能是近期（24 小时内）暴露于环境中的信息更丰富、更敏感的指标。压力源。我们之前发现了在实验刺激下丘脑-垂体-肾上腺轴期间，幼年北象海豹的内脂中上调的基因。在这项研究中，我们测量了不同生理状态的未经处理的幼年象海豹内脂中这些基因子集的基线表达水平，并将其与其他压力标记（身体状况指数、皮质类固醇和甲状腺激素水平）相关联。 10 个基因的表达，包括与脂质代谢（ACSL1、HMGCS2、CDO1）、氧化还原稳态（GPX3）、脂肪因子信号传导（ADIPOQ）、脂滴形成（PLIN1、CIDEA）和脂肪生成（DKK1、AZGP1、TGFBI）相关的基因由三个主要成分描述，并与皮质醇和甲状腺激素水平相关。 值得注意的是，基线基因表达水平可以预测循环激素水平，这表明这些标记可能是无法进行血液采样的海洋哺乳动物物种暴露于应激源的潜在指标。类似的方法可用于识别其他组织中的物种特异性应激标记，这些组织可以通过远程活检飞镖从自由放养的海洋哺乳动物（例如外层鲸脂和皮肤）中取样。