广温性鱼类耐受环境极端温度的代谢补偿机制的研究

As global temperatures rise, there is a growing need to understand the physiological mechanisms that determine an organism's thermal niche. Although the concept of oxygen and capacity limited thermal tolerance (OLTT) has recently been proposed as a unifying principle for understanding the mechanistic basis of whole-organism thermal tolerance in ectotherms, the precise metabolic mechanisms involved in establishing both the upper and lower thermal limits of organisms are still poorly understood. Here, we suggest that adjustments in mitochondrial capacity with thermal acclimation are associated with a shift in thermal tolerance of whole-organism using the southern catfish (Silurus meridionalis).In the present study, we adopt an integrative approach including experimental ecology, cell biology and molecular biology technology to assesse the thermal tolerance scope, whole-organism metabolic rate and mitochondrial properties of southern catfish acclimated to different temperatures. This study is designed to investigate the internal relationship between mitochondrial properties and whole-organism responses to temperature and demonstrate the bioenergetics mechanisms that determine thermal niche of fish. The present experimental data will provide evidence to re-evaluate the OLTT hypothesis at subcellular level. Meanwhile, new theory and method will be provide to identify the mechanisms of aerobic capacity modulation to thermal acclimation.

随着全球气候变暖，决定动物热生态位的生理机制成为亟待解决的热点问题。虽然"供氧能力限制假说(OLTT)"对于变温动物在个体水平上的温度耐受范围的解释已被广泛接受，但与之相关的代谢调节机理并无实验依据。本研究提出将鱼类个体适应环境极端温度的调节机制与线粒体代谢补偿相联系为切入点的崭新思路。以南方鲇为实验对象，把实验生态学的研究方法与细胞生物学和分子生物学的实验技术相结合，通过检测经不同温度驯化后鱼体温度耐受范围及其组织线粒体的代谢补偿效应的变化特征，以探讨鱼体对极端温度的适应性与线粒体代谢调节机制的内在联系，揭示决定鱼类热生态位的能量学机理。为验证OLTT假说提供国际学术界甚为缺乏的亚细胞水平的实验资料，为阐明鱼类适应环境极端温度的代谢调节机制提供崭新的理论和方法。

本项目通过选择国际学术界十分关注的OLTT假说的实验验证为课题，提出将鱼类个体适应环境极端温度的调节机制与线粒体代谢补偿的调节机制相联系为切入点的崭新思路。以南方鲇为实验对象，把实验生态学的研究方法与细胞生物学实验技术相结合，通过检测经不同温度驯化后鱼体个体水平和线粒体水平的代谢能力及其温度耐受范围的变化规律，比较南方鲇在应对环境温度变化中其个体、器官以及线粒体水平的代谢适应性调节机制的，探讨了鱼体对极端温度的适应性与线粒体代谢调节机制的内在联系。结果发现，低温驯化降低了个体水平代谢的耐受下限温度，而高温驯化则提高了其耐受上限温度。温度驯化改变了南方鲇组织线粒体的代谢能力，低温驯化增加了鱼体组织线粒体的代谢能力，但在氧供给受限的情况下，该种线粒体代谢能力的增加会引起热耐受上限温度的降低，即温度驯化对鱼体组织线粒体代谢能力的调整会引起鱼体热耐受窗的改变。符合OLTT假说所预测的规律，为验证OLTT假说首次提供了细胞及亚细胞水平的实验证据。该项目研究成果发表学术论文8篇，其中SCI收录2篇，圆满完成各项指标。