COLLABORATIVE RESEARCH: Physiological Adaptation to Extreme Environments: Genes, Function, and Evolutionary Patterns

极端环境允许调查生命应对远离平均水平的环境条件的能力和局限性。富含硫化氢的泉水代表了一些最极端的淡水环境，因为硫化氢会阻止动物细胞产生能量。尽管如此，一些鱼已经在美洲各地的硫化物泉水中定居，目前尚不清楚它们如何忍受有毒到导致大多数其他生物死亡的条件。该项目将比较生活在邻近硫化物或非硫化物生境中的密切相关种群，以确定导致对这种有毒化学物质耐受性的遗传、生化和生理特征的差异。它涉及识别耐硫化氢和敏感种群之间的遗传差异，特别是与受硫化氢毒性或解毒影响的途径相关的基因差异。此外，还将在存在或不存在硫化氢的情况下测量鱼类种群的耐受性和敏感性。该项目将对硫化氢生理耐受性的潜在机制以及动物在存在物理化学应激源时的工作方式产生新的见解。鉴于硫化氢在细胞过程和疾病形成中的作用，这也对生物医学应用产生了影响。该项目为各级高等教育的参与者提供了综合生物学的培训机会。它还将通过在当地动物园举办展览和高中教师的参与来促进科学教育和公共宣传，该展览将为STEM领域的K-12教育制定执行下一代科学教育标准的教案。利用毒理学和生物医学研究的知识，这个项目提出了关于生理适应自然富含硫化氢环境的机制的假说，并专注于线粒体氧化磷酸化途径(OXPHOS)的组成和相关。这些成分包括硫化氢毒性的靶标以及参与硫化氢解毒的酶。据预测，在硫化物泉水种群中，焦点成分被调制或修饰，从而使个体具有更强的抵御H_2S浓度升高的能力，增强了通过酶解毒H_2S的能力，以及通过利用H_2S作为底物来维持甚至增加线粒体能量产生的能力。此外，可以预见，OXPHOS组分的修饰在定居在硫化物泉水中的独立谱系中重复发生。为了验证这些预测，这个项目集中在一个已经建立的研究硫化氢适应的模型系统(Poecilia Miciana)上，并有三个主要的经验部分：(1)利用高通量测序技术表征候选基因的转录和编码变异，并随后验证对蛋白质浓度和结构的影响。(2)在体外和体内对H_2S解毒和生物能量学转录和编码变异的功能影响的量化。(3)比较硫化物生境和非硫化物生境中十几个独立种群对的基因序列和表达差异，以检验收敛情况。

Extreme environments allow for the investigation of life's capacity and limitations to cope with far-from-average environmental conditions. Springs rich in hydrogen sulfide represent some of the most extreme freshwater environments, because hydrogen sulfide halts energy production in animal cells. Nonetheless, some fish have colonized sulfide springs throughout the Americas, and it remains unknown how they can tolerate conditions so toxic that most other organisms perish. This project will compare closely related populations that live in adjacent sulfidic or nonsulfidic habitats to identify differences in genetic, biochemical, and physiological traits that underlie tolerance to this noxious chemical. It involves the identification of genetic differences between hydrogen sulfide-tolerant and susceptible populations, particularly in genes associated with pathways affected by hydrogen sulfide toxicity or detoxification. In addition, the tolerance and the susceptibility of fish populations will be measured in the presence or absence of hydrogen sulfide. This project will yield new insights into mechanisms underlying physiological tolerance to hydrogen sulfide and the workings of animals in the presence of physiochemical stressors. Given hydrogen sulfide's role in cellular processes and disease formation, this also has implications for biomedical applications. This project provides training opportunities in integrative biology for participants at all levels of higher education. It will also contribute to science education and public outreach through the generation of an exhibit at a local zoo and the involvement of high school teachers that will generate lesson plans implementing next generation science education standards for K-12 education in STEM fields. Leveraging knowledge from toxicological and biomedical studies, this project addresses hypotheses about mechanisms of physiological adaptation to naturally H2S-rich environments and focuses on components of and associated with the oxidative phosphorylation pathway (OXPHOS) in mitochondria. These components include targets of H2S toxicity as well as enzymes involved in H2S detoxification. It is predicted that focal components are modulated or modified in sulfide spring populations, such that individuals have an increased ability to withstand elevated H2S concentrations, an increased ability to detoxify H2S enzymatically, and an ability to maintain or even increase mitochondrial energy production by using H2S a substrate to fuel metabolism. Furthermore, it is anticipated that modification of OXPHOS components has occurred repeatedly across independent lineages that have colonized sulfide springs. To test these predictions, this project focuses on an established model system (Poecilia mexicana) for the investigation of H2S adaptation and has three major empirical components: (1) Characterization of transcriptional and coding variation in candidate genes by use of high-throughput sequencing techniques and subsequent validation of effects on protein concentrations and structure. (2) Quantification of functional consequences of transcriptional and coding variation for H2S detoxification and bioenergetics both in vitro and in vivo. (3) Comparison of gene sequence and expression variation across a dozen independent population pairs from sulfidic and non-sulfidic habitats to test for convergence.