Tobler Michael, Henpita Chathurika, Bassett Brandon, Kelley Joanna L, Shaw Jennifer H
Department of Zoology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK 74078, USA.
Center for Veterinary Health Sciences, Oklahoma State University, 205 McElroy Hall, Stillwater, OK 74078, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2014 Sep;175:7-14. doi: 10.1016/j.cbpa.2014.04.012. Epub 2014 May 9.
Disentangling the effects of plasticity, genetic variation, and their interactions on organismal responses to environmental stressors is a key objective in ecological physiology. We quantified the expression of five candidate genes in response to hydrogen sulfide (H2S) exposure in fish (Poecilia mexicana, Poeciliidae) from a naturally sulfide-rich environment as well as an ancestral, non-sulfidic population to test for constitutive and environmentally dependent population differences in gene expression patterns. Common garden raised individuals that had never encountered environmental H2S during their lifetime were subjected to short or long term H2S exposure treatments or respective non-sulfidic controls. The expression of genes involved in responses to H2S toxicity (cytochrome c oxidase, vascular endothelial growth factor, and cytochrome P450-2J6), H2S detoxification (sulfide:quinone oxidoreductase), and endogenous H2S production (cystathionine γ lyase) was determined in both gill and liver tissues by real time PCR. The results indicated complex changes in expression patterns that--depending on the gene--not only differed between organs and populations, but also on the type of H2S exposure. Populations differences, both constitutive and H2S exposure dependent (i.e., plastic), in gene expression were particularly evident for sulfide:quinone oxidoreductase, vascular endothelial growth factor, and to a lesser degree for cytochrome P450-2J6. Our study uncovered putatively adaptive modifications in gene regulation that parallel previously documented adaptive changes in phenotypic traits.
厘清可塑性、遗传变异及其相互作用对生物体应对环境应激源的影响，是生态生理学的一个关键目标。我们对来自富含硫化物的自然环境以及一个原始的、无硫化物种群的鱼类（墨西哥食蚊鱼，食蚊鱼科）暴露于硫化氢（H2S）时五个候选基因的表达进行了量化，以测试基因表达模式中组成型和环境依赖性的种群差异。将在一生中从未接触过环境H2S的共同养殖个体进行短期或长期H2S暴露处理或相应的无硫化物对照处理。通过实时PCR测定鳃和肝脏组织中参与H2S毒性反应（细胞色素c氧化酶、血管内皮生长因子和细胞色素P450-2J6）、H2S解毒（硫化物：醌氧化还原酶）和内源性H2S产生（胱硫醚γ裂解酶）的基因的表达。结果表明，表达模式存在复杂变化，具体取决于基因，这些变化不仅在器官和种群之间存在差异，而且在H2S暴露类型上也存在差异。对于硫化物：醌氧化还原酶、血管内皮生长因子，以及在较小程度上对于细胞色素P450-2J6，基因表达中的种群差异，包括组成型和H2S暴露依赖性（即可塑性）差异尤为明显。我们的研究揭示了基因调控中可能的适应性修饰，这些修饰与先前记录的表型性状的适应性变化相似。
