Evolution of steroid hormone signaling and size determination in Cnidaria and Xenacoelomorpha

类固醇激素控制着重要的发育开关，因为它们诱导性成熟并介导许多双侧动物生长阶段的终止。它们对生长、繁殖力、发育时间和资源利用进行了关键的权衡，并依赖于内在的遗传和外在的环境信号。因此，它们是发育可塑性和适应性的关键组成部分。核受体（nuclear receptor， NR）是一个在发育和生理中具有多种功能的受体家族。类固醇激素和相应的NRs何时进化尚不清楚，但有关这一主题的信息有望深入了解类固醇的祖先功能及其对各种身体计划和生活方式的贡献。系统发育和生化预测将类固醇受体的进化日期定在刺胞动物与两侧刺胞动物的分裂上，但在早期出现的两侧刺胞动物和刺胞动物的代表性物种中，没有类固醇激素/ nr在发育中的功能证据。我将研究在刺胞属Hydra vulgaris和Hofstenia Bilateria miamia （Xenacoelomorpha，所有其他双边门的姐妹类群）中类固醇结合核糖核酸的进化和功能，以了解它们在变化的环境条件下调节体型的祖先功能。我将使用系统发育方法与原位杂交配对来识别发育和环境响应的nr。通过细胞术观察环境变化和NRs诱变后的细胞变化，通过层析和质谱法鉴定两种植物提取物中的类固醇激素。该项目将阐明所有双侧虫的原型分子机制和环境依赖性发育决策（表型可塑性）的进化。

Steroid hormones control important developmental switches as they induce sexual maturity and mediate termination of the growth phase for many bilaterian species. They set crucial trade-offs for growth, fecundity, developmental time, and resource utilization and are dependent on intrinsic genetic as well as extrinsic environmental signals. Hence, they are key components for developmental plasticity and adaptation. Steroid hormones are recognized by nuclear receptors (NR), a diverse receptor family with various functions in development and physiology. When steroid hormones and the corresponding NRs evolved is insufficiently understood, but information on this topic promises insights in the ancestral function of steroids and their contribution to diverse body plans and life styles. Phylogenetic and biochemical predictions date the evolution of steroid receptors to the cnidarian-bilaterian split, without functional evidences of steroid hormones/ NRs in development in representative species in early emerging Bilateria and Cnidaria.I will study the evolution and function of steroid-binding NRs in the Cnidaria Hydra vulgaris and the Bilateria Hofstenia miamia (Xenacoelomorpha, a sister group to all other Bilateria) to understand their ancestral function in body size regulation under changing environmental conditions. I will use a phylogenetic approach paired with insitu hybridization to identify developmentally and environmentally responsive NRs. Cellular alterations upon changing environments and after mutagenesis of NRs will be observed by cytometry, while steroid hormones will be identified in extracts of the two species by chromatography and mass spectrometry. The project will elucidate the prototypic molecular mechanism and the evolution of environmental dependent developmental decisions (phenotypic plasticity) of all Bilateria.