中华鳖胚胎发育响应巢温变化的地理格局与机制

Under the background of climate warming, how animals response to temperature variation is one of the hotspots in the field of current zooecology. The development of reptile embryos is affected by population and temperature, but the geographic pattern and the underlying mechanisms of temperature response are largely unexplored. The Chinese soft-shelled turtle (Pelodiscus sinensis) is widespread in China, so the eggs of this turtle in three locations of high (Shandong), medium (Hunan) and low (Guangxi) latitudes are selected as objects in this study. We conduct reciprocal transplant experiments of egg incubation under different regimes of temperatures, which mimic the nest temperature we monitored before in each field. We measure the metabolic rate and developmental rate of embryos, and analyze the dynamic changes of thyroxine (T3) level, the density and function of mitochondria, the activity and expression of some key metabolic enzymes during embryo development. At last, we will analyze the transcriptomic data of embryonic liver to study the molecular mechanism of the response of all metabolic enzymes to temperature variation, holistically. This study aims to 1) elucidate the geographical pattern and the underlying physiological, biochemical and molecular strategies of embryonic response to geographical variations in nest temperatures of the Chinese soft-shelled turtle, and 2) lay a theoretical foundation for predicting how reptile embryos respond to climate warming.

在气候变暖背景下，动物如何响应温度变化是当前动物生态学领域的研究热点之一。爬行动物胚胎发育受种群和温度的影响，但对其响应温度变化的地理格局和机制尚知之甚少。中华鳖在中国广泛分布，因此本研究选择高（聊城）、中（湖南）、低（广西）三个纬度的中华鳖卵为对象，根据前期测定的各种群巢温，室内开展模拟不同种群巢温的卵交互孵化实验，测定孵化过程中胚胎的代谢率和发育速率；分析胚胎在孵化过程中甲状腺激素水平、线粒体密度与功能以及关键代谢酶活性和表达的动态变化；通过胚胎肝脏转录组数据全面分析代谢酶对温度变化响应的分子机理。本研究旨在阐明中华鳖胚胎发育响应巢温变化的地理格局及生理生化与分子机制，并为预测爬行动物胚胎如何响应气候变暖奠定理论基础。

在气候变暖背景下，动物如何响应温度变化是当前动物生态学领域的研究热点之一。爬行动物胚胎发育受种群和温度的影响，但对其响应温度变化的地理格局和机制尚知之甚少。中华鳖在中国广泛分布，因此本研究选择高（聊城）低（广西）两个纬度的中华鳖卵为对象，根据前期测定的各种群巢温，室内开展模拟不同种群巢温的卵交互孵化实验，随后通过测定胚胎的代谢速率、关键代谢酶活性以及运用组学技术，探究不同种群中华鳖胚胎发育速率差异的机制。结果表明，高纬度中华鳖胚胎通过提升发育过程中的代谢速率促进其发育速率高于低纬度种群。胚胎肝脏代谢组和转录组联合分析发现，高纬度中华鳖胚胎通过增强PPARα和花生四烯酸的正反馈调节，促进其提高自身代谢速率。基因组重测序显示，PPARα基因上的突变有可能导致其在高纬度种群中的高表达，但仍需进一步实验来证明这些突变位点在调控PPARα表达中的功能。本研究阐明了中华鳖胚胎发育响应巢温变化的地理格局及生理生化与分子机制，并为预测爬行动物胚胎如何响应气候变暖奠定理论基础。