台灣熱帶與副熱帶地區的萼柱珊瑚熱抗性與逆境蛋白表現的空間差異

Abstract

近幾十年來由於全球暖化與聖嬰現象發生頻率增加導致海水水溫上升，造成珊瑚大量白化。珊瑚白化與溫度、光照變化的關係在過去十幾年來已成為珊瑚礁研究中重要的研究主題。研究發現，珊瑚可能可以適應溫度上升的現象。這種耐熱的能力可能不只是因為珊瑚體內具有耐熱的共生藻，也是珊瑚共生體長期適應環境後，細胞對熱產生較好的分子防禦機制（例如：抗逆境或抗氧化蛋白）。本論文採集副熱帶的野柳、熱帶的墾丁核三廠出熱水出水口及台灣西邊的澎湖代表生長不同緯度、不同海水水溫環境的萼柱珊瑚，進行加熱實驗。觀察三地珊瑚的耐熱程度差異及共生藻和宿主珊瑚細胞內分子防禦機制產生的程度與快慢，發現在熱帶核三廠出水口的萼柱珊瑚具有較高的耐熱能力。其細胞內的抗逆境蛋白（Hsp70）表現雖較野柳及澎湖地區的緩慢，但具有最高的表現量。因此，生長在海水溫度平均較高的萼柱珊瑚的較適應高海水溫度而具有較好的耐熱能力。而且，此種耐熱的分子防禦機制在抗逆境蛋白(Hsp70)的表現量上，大部份是由共生藻細胞所提供。

Coral reefs have been extensive and accelerating degradation worldwide probably due to a continuous global warming since industrial revolution. One of the causes for global coral degradation is “coral bleaching”, a syndrome known as loss of symbiotic algae (dinoflagellate genus Symbiodinium), the algae pigment, or both. In the last decades, much attention has been focused on diversity of Symbiodinium phylotypes identified by ribosomal RNA gene, and their potential functions on resistance and resilience of coral reefs to heat stress. Previous results indicated that the cellular defense mechanisms may be attributed to the physiological response to the stress in coral hosts or in conjunction with symbiotic algae. In this study, Stylophora pistillata collected from Penghu, Yeliu, and the elevated temperature water outlet of the third nuclear plant in Kenting (NUKE) was used as the model coral to examine the thermal resistance and acclimatisation. Our result reveals that thermal acclimatisation resulted thermal resistance in S. pistillata collected from NUKE are higher than that from Yeliu and Penghu Island and corals expressed more Hsp70 in the samples from NUKE than that from Yeliu and Penghu. Symbiodinium cells showed more contribution on thermal resistance than host cells in this study. The role of sub-clade typing of the Symbiodinium in these corals required further examination.