Ghaffari Hamze, Wang Wei, Li Ao, Zhang Guofan, Li Li
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
University of Chinese Academy of Sciences, Beijing, China.
Front Physiol. 2019 Sep 10;10:1137. doi: 10.3389/fphys.2019.01137. eCollection 2019.
Investigating the physiological mechanisms of closely related species that exhibit distinct geographic distributions and thermal niches is essential for understanding their thermal tolerance capacities and local adaptations in view of climate warming. The variations in upper thermal limits (LT) under acute heat shock and cardiac activity, standard metabolic rate (SMR), anaerobic metabolite production and molecular responses (expression of molecular chaperones and glycolysis metabolism genes) under increasing temperatures in two oyster subspecies were studied. The populations of two oyster subspecies, and , exhibit different latitudinal distributions along the northern and southern coastlines of China, respectively, which experience different environmental conditions. The LT was significantly higher, by ∼1°C, in the southern than in the northern oysters. In both subspecies, temperature increases had powerful effects on heart rate, SMR and gene expression. The southern oysters had the highest Arrhenius breakpoint temperatures for heart rate (31.4 ± 0.17°C) and SMR (33.09°C), whereas the heart rate (28.86 ± 0.3°C) and SMR (29.22°C) of the northern oysters were lower. The same patterns were observed for the coefficients. More thermal sensitivity was observed in the northern oysters than in their southern counterparts, as the heat-shock proteins (HSPs) in the northern oysters were expressed first and had a higher induction at a lower temperature than those of southern oysters. Furthermore, different expression patterns of energetic metabolism genes (, and ) were observed. In the northern oysters, increasing anaerobic glycolysis genes () and end products (succinate) were found at 36-43°C, indicating a transition from aerobic to anaerobic metabolism and a lower aerobic scope compared with the southern oysters. These two subspecies experience different environmental conditions, and their physiological performances suggested species-specific thermal tolerance windows in which the southern oysters, with mild physiological flexibility, had a higher potential capability to withstand heat stress. Overall, our results indicate that comparing and unifying physiological and molecular mechanisms can provide a framework for understanding the likely effects of global warming on marine ectotherms in intertidal regions.
鉴于气候变暖，研究具有不同地理分布和热生态位的近缘物种的生理机制，对于理解它们的耐热能力和局部适应性至关重要。研究了两种牡蛎亚种在急性热休克下的热上限（LT）变化以及心脏活动、标准代谢率（SMR）、无氧代谢产物产生和温度升高时的分子反应（分子伴侣和糖酵解代谢基因的表达）。两种牡蛎亚种， 和 ，分别在中国北部和南部沿海呈现不同的纬度分布，经历不同的环境条件。南部牡蛎的LT显著高于北部牡蛎，约高1°C。在两个亚种中，温度升高对心率、SMR和基因表达都有显著影响。南部牡蛎的心率（31.4±0.17°C）和SMR（33.09°C）的阿伦尼乌斯断点温度最高，而北部牡蛎的心率（28.86±0.3°C）和SMR（29.22°C）较低。 系数也观察到相同的模式。与南部牡蛎相比，北部牡蛎表现出更高的热敏感性，因为北部牡蛎中的热休克蛋白（HSPs）首先表达，并且在较低温度下比南部牡蛎具有更高的诱导水平。此外，还观察到能量代谢基因（ 、 和 ）的不同表达模式。在北部牡蛎中，在36 - 43°C时发现无氧糖酵解基因（ ）和终产物（琥珀酸）增加，表明从有氧代谢向无氧代谢的转变，并且与南部牡蛎相比有氧范围更低。这两个亚种经历不同的环境条件，它们的生理表现表明了物种特异性的耐热窗口，其中生理灵活性较低的南部牡蛎具有更高的耐热应激潜力。总体而言，我们的结果表明，比较和统一生理和分子机制可以为理解全球变暖对潮间带海洋变温动物可能产生的影响提供一个框架。
