Green fluorescence from cnidarian hosts attracts symbiotic algae
Green fluorescence from cnidarian hosts attracts symbiotic algae
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DOI：
10.1073/pnas.1812257116
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发表时间：
2019-02-05
影响因子：
11.1
通讯作者：
Minagawa, Jun
中科院分区：
文献类型：
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作者：
Aihara, Yusuke;Maruyama, Shinichiro;Minagawa, Jun
造礁珊瑚在营养贫乏的海洋环境中茁壮成长，因为它们与共生藻属的光合甲藻有着专性的共生关系。大多数珊瑚通过从环境中吸收共生藻而建立共生关系。珊瑚在其生命史的大部分时间里都是固着的，而自由生活的共生藻是能动的;因此，吸引共生藻的机制将大大增加宿主和共生体之间相遇的可能性。在这里，我们研究了珊瑚是否可以吸引自由生活的能动共生藻的绿色荧光，由内源性绿色荧光蛋白的激发发出的紫蓝光。发现共生藻对弱绿色光和强紫蓝光分别具有正趋光性和负趋光性。在导致珊瑚发出绿色荧光的光照条件下，（例如，强烈的蓝光），共生藻被吸引到活珊瑚碎片。共生藻也被吸引到一个人工绿色荧光染料与类似的激发和发射光谱珊瑚-GFP。在该领域，更多的共生藻被发现在陷阱涂上绿色荧光染料比对照组。我们的研究结果揭示了珊瑚宿主与其潜在共生体之间的生物信号机制。
Reef-building corals thrive in nutrient-poor marine environments because of an obligate symbiosis with photosynthetic dinoflagel-lates of the genus Symbiodinium. Symbiosis is established in most corals through the uptake of Symbiodinium from the environment. Corals are sessile for most of their life history, whereas free-living Symbiodinium are motile; hence, a mechanism to attract Symbiodinium would greatly increase the probability of encounter between host and symbiont. Here, we examined whether corals can attract free-living motile Symbiodinium by their green fluorescence, emitted by the excitation of endogenous GFP by purple-blue light. We found that Symbiodinium have positive and negative phototaxis toward weak green and strong purpleblue light, respectively. Under light conditions that cause corals to emit green fluorescence, (e.g., strong blue light), Symbiodinium were attracted toward live coral fragments. Symbiodinium were also attracted toward an artificial green fluorescence dye with similar excitation and emission spectra to coral-GFP. In the field, more Symbiodinium were found in traps painted with a green fluorescence dye than in controls. Our results revealed a biological signaling mechanism between the coral host and its potential symbionts.