Madeira Carolina, Madeira Diana, Diniz Mário S, Cabral Henrique N, Vinagre Catarina
MARE - Marine and Environmental Sciences Centre, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.
UCIBIO, REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
Comp Biochem Physiol A Mol Integr Physiol. 2017 Feb;204:104-112. doi: 10.1016/j.cbpa.2016.11.018. Epub 2016 Nov 25.
Knowledge of thermal stress biology for most tropical fish species in reef ecosystems under climate change is still quite limited. Thus, the objective of this study was to measure the time-course changes of thermal stress biomarkers in the commercially exploited coral reef fish Amphiprion ocellaris, during a laboratory simulated event of increased temperature. Heat shock protein 70kDa (Hsp70) and total ubiquitin (Ub) were determined in the muscle (lethal method) and in the fin (non-lethal alternative method) under two temperature treatments (control - 26°C and elevated temperature - 30°C) throughout one month with weekly samplings. Results suggest that biomarker basal levels are tissue-specific and influence the degree of response under temperature exposure. Responses were highly inducible in the muscle but not in fin tissue, indicating that the latter is not reliable for monitoring purposes. Thermal stress was observed in the muscle after one week of exposure (both biomarkers increased significantly) and Ub levels then decreased, suggesting the animals were able to acclimate by maintaining high levels of Hsp70 and through an effective protein turnover. In addition, the results show that mortality rates did not differ between treatments. This indicates that A. ocellaris is capable of displaying a plastic response to elevated temperature by adjusting the protein quality control system to protect cell functions, without decreasing survival. Thus, this coral reef fish species presents a significant acclimation potential under ocean warming scenarios of +4°C. Monitoring of thermal stress through a non-lethal method, fin-clipping, although desirable proved to be inadequate for this species.
对于珊瑚礁生态系统中大多数热带鱼类物种在气候变化下的热应激生物学知识仍然相当有限。因此，本研究的目的是在实验室模拟温度升高事件期间，测量商业开发的珊瑚礁鱼类眼斑双锯鱼热应激生物标志物的时间进程变化。在两种温度处理（对照 - 26°C和高温 - 30°C）下，通过每周采样，在一个月的时间里，测定肌肉（致死方法）和鳍（非致死替代方法）中的热休克蛋白70kDa（Hsp70）和总泛素（Ub）。结果表明，生物标志物的基础水平具有组织特异性，并影响温度暴露下的反应程度。肌肉中的反应高度可诱导，但鳍组织中则不然，这表明鳍组织对于监测目的而言不可靠。暴露一周后在肌肉中观察到热应激（两种生物标志物均显著增加），然后Ub水平下降，这表明动物能够通过维持高水平的Hsp70和有效的蛋白质周转来适应环境。此外，结果表明不同处理之间的死亡率没有差异。这表明眼斑双锯鱼能够通过调整蛋白质质量控制系统来保护细胞功能，从而对温度升高表现出可塑性反应，而不会降低存活率。因此，在海洋升温4°C的情况下，这种珊瑚礁鱼类具有显著的适应潜力。通过非致死方法剪鳍来监测热应激，虽然理想，但事实证明对该物种来说并不充分。
