Altered thyroid hormone signalling in accelerated metamorphosis in desert frogs

激素影响身体每个器官的发育，并可能是生物多样性进化的基础。特别是，甲状腺激素（TH）在大脑和骨骼发育中起着关键作用，但TH在发育中的作用在脊椎动物物种中有很大差异。事实上，TH生理学的进化变化与青蛙和蝾螈生活史中发现的巨大多样性有关。如此重要的激素如何改变其在进化中的发育作用尚不清楚。为了更全面地了解TH在进化中的作用，本项目将研究TH受体（TRs）表达改变在沙漠蛙加速变态进化中的作用。青蛙的变态依赖于TH，沙漠青蛙的幼虫期比非沙漠青蛙的幼虫期短。根据我们的初步数据，据推测，沙漠物种将有一个更强大的响应TH相比，非沙漠物种的幼虫期较短。该项目的成功完成将在功能上测试TR表达的进化增加对变态率的影响。这项研究的基本原理是，改变TR表达如何影响青蛙物种之间的变态的知识将促进我们对这种强大的激素系统的发育和进化作用的理解。这个研究项目与教育的整合将通过让本科生和研究生参与研究项目来完成，不仅在研究项目中，而且还通过在会议上展示成功的研究来完成。目前的项目通过国际合作和为本科教学提供教育材料来加强研究和教育的基础设施。拟议研究的结果将通过在同行评审的期刊上发表文章和在专业会议上作介绍而广泛传播，项目中使用的所有材料将存放在科学界可用的研究收藏中。最后，这项研究预计将有利于整个社会，主要是通过提高公众对进化和生物多样性基础的认识。

Hormones influence the development of every organ in the body and may underlie the evolution of biodiversity. In particular, thyroid hormone (TH) plays critical roles in brain and skeletal development, yet the role TH plays in development varies widely across vertebrate species. Indeed, evolutionary changes in TH physiology have been implicated in the enormous diversity found in frog and salamander life history. How such an important hormone can change its developmental role in evolution is not known. To more fully understand the role of TH in evolution, this project will examine the role of altered expression of TH receptors (TRs) underlying the evolution of accelerated metamorphosis in desert frogs. Frog metamorphosis is dependent on TH, and desert frog species have shorter larval periods compared to their non-desert relatives. Based on our preliminary data, it is hypothesized that desert species will have a more robust response to TH compared to non-desert species underlying their shorter larval period. Successful completion of this project will functionally test the effect of an evolutionary increase in TR expression on the rate of metamorphosis. The rationale for this research is that knowledge of how altered TR expression affects metamorphosis between frog species will advance our understanding of the developmental and evolutionary roles of this powerful hormone system. Integration of this research project with education will be accomplished by involving undergraduate and graduate students, not only in the research project, but also by enabling presentations of successful research at conferences. The current project enhances infrastructure for research and education through international collaborations and by providing educational material for undergraduate teaching. Results of the proposed research will be disseminated widely by publications in peer-reviewed journals and presentations at professional meetings, and all material used in the project will be deposited in research collections available for the scientific community. Finally, the research is expected to benefit society as a whole, primarily through bringing awareness to the general public of the underpinnings of evolution and biodiversity.