Collins Michael, Clark Melody S, Spicer John I, Truebano Manuela
Marine Biology and Ecology Research Centre, School of Biological and Marine Sciences University of Plymouth Plymouth UK.
British Antarctic Survey Natural Environment Research Council Cambridge UK.
Evol Appl. 2020 Oct 22;14(2):577-587. doi: 10.1111/eva.13142. eCollection 2021 Feb.
The adaptive value of phenotypic plasticity for performance under single stressors is well documented. However, plasticity may only truly be adaptive in the natural multifactorial environment if it confers resilience to stressors of a different nature, a phenomenon known as cross-tolerance. An understanding of the mechanistic basis of cross-tolerance is essential to aid prediction of species resilience to future environmental change. Here, we identified mechanisms underpinning cross-tolerance between two stressors predicted to increasingly challenge aquatic ecosystems under climate change, chronic warming and hypoxia, in an ecologically-important aquatic invertebrate. Warm acclimation improved hypoxic performance through an adaptive hypometabolic strategy and changes in the expression of hundreds of genes that are important in the response to hypoxia. These 'frontloaded' genes showed a reduced reaction to hypoxia in the warm acclimated compared to the cold acclimated group. Frontloaded genes included stress indicators, immune response and protein synthesis genes that are protective at the cellular level. We conclude that increased constitutive gene expression as a result of warm acclimation reduced the requirement for inducible stress responses to hypoxia. We propose that transcriptional frontloading contributes to cross-tolerance between stressors and may promote fitness of organisms in environments increasingly challenged by multiple anthropogenic threats.
表型可塑性在单一应激源下对性能的适应性价值已有充分记录。然而，可塑性只有在赋予对不同性质应激源的恢复力时，才可能在自然多因素环境中真正具有适应性，这种现象称为交叉耐受性。了解交叉耐受性的机制基础对于帮助预测物种对未来环境变化的恢复力至关重要。在这里，我们在一种具有生态重要性的水生无脊椎动物中，确定了两种应激源之间交叉耐受性的潜在机制，预计在气候变化下，这两种应激源将对水生生态系统构成越来越大的挑战，即长期变暖和缺氧。温暖驯化通过一种适应性低代谢策略以及数百个在缺氧反应中起重要作用的基因表达变化，改善了缺氧性能。与冷驯化组相比，这些“预加载”基因在温暖驯化组中对缺氧的反应减弱。预加载基因包括在细胞水平上具有保护作用的应激指标、免疫反应和蛋白质合成基因。我们得出结论，温暖驯化导致的组成型基因表达增加，降低了对缺氧诱导应激反应的需求。我们提出，转录预加载有助于应激源之间的交叉耐受性，并可能促进生物体在日益受到多种人为威胁挑战的环境中的适应性。
