Dissecting molecular stress networks: identifying nodes of divergence between life-history phenotypes

The complex molecular network that underlies physiological stress response is comprised of nodes (proteins, metabolites, mRNAs, etc.) whose connections span cells, tissues and organs. Variable nodes are points in the network upon which natural selection may act. Thus, identifying variable nodes will reveal how this molecular stress network may evolve among populations in different habitats and how it might impact life-history evolution. Here, we use physiological and genetic assays to test whether laboratory-born juveniles from natural populations of garter snakes (Thamnophis elegans), which have diverged in their life-history phenotypes, vary concomitantly at candidate nodes of the stress response network, (i) under unstressed conditions and (ii) in response to an induced stress. We found that two common measures of stress (plasma corticosterone and liver gene expression of heat shock proteins) increased under stress in both life-history phenotypes. In contrast, the phenotypes diverged...

支撑生理应激反应的复杂分子网络由各类节点（蛋白质、代谢物、信使核糖核酸[mRNA]等）构成，这些节点间的连接横跨细胞、组织与器官。可变节点是该分子网络中可受自然选择作用的位点。因此，鉴定可变节点能够揭示该分子应激网络在不同生境的种群间会如何演化，以及其可能对生活史进化产生何种影响。
本研究通过生理与遗传学实验，检测来自自然种群的实验室孵化幼束带蛇（garter snake, Thamnophis elegans）——该种群的生活史表型已发生分化——在应激反应网络候选节点上的变异情况，分别在（i）非应激条件下，以及（ii）诱导应激处理后两种情境下开展检测。
本研究发现，两种常用的应激检测指标——血浆皮质酮与肝脏热休克蛋白（heat shock proteins）的基因表达量——在两种生活史表型的个体中均会在应激条件下升高。与之相反，两种生活史表型出现了分化……