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

极端环境允许研究生命的能力和限制，以应付远非平均的环境条件。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的能量产生。尽管如此，一些鱼类已经在整个美洲的硫化物泉中定居下来，人们仍然不知道它们是如何忍受如此有毒的环境的，以至于大多数其他生物都会死亡。该项目将比较生活在邻近硫化物和非硫化物栖息地的近亲种群，以确定遗传、生化和生理性状的差异，这些差异是对这种有毒化学物质耐受性的基础。它涉及鉴定耐硫化氢人群和易感人群之间的遗传差异，特别是与受硫化氢毒性或解毒影响的途径相关的基因。此外，将在硫化氢存在或不存在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机制和动物在物理化学应激源存在下的工作机制产生新的见解。鉴于硫化氢在细胞过程和疾病形成中的作用，这对生物医学应用也有影响。该项目为各级高等教育的参与者提供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，以及让高中教师参与制定实施STEM领域K-12教育的下一代科学教育标准的课程计划，为科学教育和公众宣传做出贡献。利用毒理学和生物医学研究的知识，该项目解决了对天然富含h2s环境的生理适应机制的假设，并重点关注线粒体氧化磷酸化途径（OXPHOS）的组成部分及其相关。这些成分包括H2S毒性靶点以及参与H2S解毒的酶。据预测，在硫化物弹簧种群中，焦点成分被调节或修饰，从而使个体具有更强的承受高浓度H2S的能力，更强的酶解毒H2S的能力，以及通过使用H2S作为底物来促进代谢来维持甚至增加线粒体能量产生的能力。此外，预计OXPHOS组分的修饰在已经定殖于硫化物泉的独立谱系中反复发生。为了验证这些预测，本项目重点研究了一个已建立的模型系统（Poecilia mexicana），用于研究H2S适应性，并有三个主要的经验组成部分：(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)体外和体内转录和编码变异对H2S解毒和生物能量学的功能影响的量化。(3)比较来自硫化物和非硫化物生境的十几对独立种群的基因序列和表达变化，以检验趋同性。

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.