Studies on diversity and stress tolerance of coral-zooxanthella symbiotic system.

珊瑚-虫黄藻共生系统多样性及耐逆性研究。

基本信息

批准号：
17570023
负责人：
HIDAKA Michio
金额：
$ 2.3万
依托单位：
University of the Ryukyus
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17570023/
关键词：
coral zooxanthellae symbiosis bleaching stress response active oxygen photochemical system thermal stress

项目摘要

To investigate bleaching mechanisms of coral-zooxanthella symbiotic system at cellular or tissue level, we have established an experimental system using coral cell aggregates (tissue balls). Tissue balls prepared from dissociated cells of Fungia sp. and Pavona divaricata were exposed to either 31°C or 25°C. Survival curves of tissue balls were markedly different between 31°C and 25°C. There was a significant negative correlation between the survival time and zooxanthella density of tissue balls at 31°C, while no significant relationship was found at 25°C. The present results showed that zooxanthellae produced harmful substances and cause damage to coral ce Is under high temperature stress. The finding that the antioxidants extended the survival time of tissue balls at high temperature suggests that zooxanthellae produce reactive oxygen species under the stress condition.To examine whether damage to zooxanthellar photosystem II (PSII) is the primary step of thermally induced coral bleaching, we assessed the relationship between the maximum quantum yield of PSII (Fv/Fm) or active PSII centers (Fv/Fo) and maximum electron transport rate (ETRmax) in the symbiotic algae of the coral Pachyseris rugosa. The I h high temperature treatment in darkness produced a significant, but reversible decline in ETRmax without any change in Fv/Fm. A minimum of 60% of the Fv/Fm or 30% of active PS II centers (Fv/Fo) is required to maintain ETRmax in the symbionts. These results suggest that the primary step of heat-induced damage in the symbiont's photosynthetic apparatus involves a component beyond the PSII, probably at the level of the dark reaction as indicated by reduced ETRmax and the PSII damage is secondary.Planulae or primary polyps of Acropora nobilis and A. palifera could be infected with zooxanthellae from various hosts. We are planning to use this experimental system to assess effects of environmental stresses on corals associated with different types of zooxanthllae.

为了在细胞或组织水平上研究珊瑚-虫黄藻共生系统的漂白机制，我们建立了一个实验系统，使用由真菌和 Pavona divaricata 分离细胞制备的珊瑚细胞聚集体（组织球）暴露于 31°。 C或25°C下组织球的存活曲线在31°C和25°C之间存在显着的负相关。 31°C时虫黄藻密度与组织球密度没有显着关系，而25°C时则没有发现显着关系。目前的结果表明，虫黄藻在高温胁迫下产生有害物质并对珊瑚造成损害，这一发现表明抗氧化剂延长了存活时间。组织球在高温下的时间表明虫黄藻在应激条件下会产生活性氧。研究虫黄藻光系统 II (PSII) 的损伤是否是热诱导珊瑚的第一步在漂白过程中，我们评估了珊瑚 Pachyseris rugosa 共生藻类的 PSII 最大量子产率 (Fv/Fm) 或活性 PSII 中心 (Fv/Fo) 与最大电子传输速率 (ETRmax) 之间的关系。黑暗处理产生显着但可逆的 ETRmax 下降，而 Fv/Fm 没有任何变化，至少 60% 的 Fv/Fm 或 30% 的活跃 PS II 中心。 (Fv/Fo) 是维持共生体中 ETRmax 所必需的。这些结果表明，共生体光合装置中热诱导损伤的第一步涉及 PSII 之外的成分，可能处于暗反应水平，如减少所示。 ETRmax 和 PSII 损害是次要的。鹿角珊瑚和帕利维拉的浮肿或原发性息肉可能被来自不同宿主的虫黄藻感染。我们计划使用这个实验系统。评估环境压力对与不同类型虫黄藻相关的珊瑚的影响。