Thermal and menthol stress induce different cellular events during sea anemone bleaching
Thermal and menthol stress induce different cellular events during sea anemone bleaching
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DOI：
10.1007/s13199-016-0406-y
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发表时间：
2016-07-01
期刊：
影响因子：
2.5
通讯作者：
Sabourault, Cecile
中科院分区：
文献类型：
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作者：
Dani, Vincent;Priouzeau, Fabrice;Sabourault, Cecile
刺胞动物-甲藻共生破坏和随后的白化是主要问题，特别是它们对珊瑚礁和温带珊瑚群落的生态影响。刺胞动物白化是由多种环境压力因素引起的，例如与全球气候变化相关的海水温度升高，以及除草剂和金属等污染物。一些细胞事件已被描述来解释共生功能障碍和漂白。过量或受损的共生体通过多种机制被清除，包括胞吐作用、细胞凋亡、坏死和自噬。然而，很少有研究根据引起白化的应激来比较同一物种中这些机制的相对参与情况。在这项研究中，我们使用了两种不同的处理方法——温度和薄荷醇——来诱导海葵白化。通过监测超微结构组织的改变，在对照样本中，我们观察到饥饿诱导的原位共生体消化或共生自噬的基础率。在薄荷醇处理的样本中，共生吞噬被强烈诱导，并且是漂白的主要细胞过程，而细胞凋亡和坏死在高温诱导的漂白中占主导地位。这些结果表明，薄荷醇处理的标本中通过自噬产生了宿主效应。这些观察结果还表明，共生体的去除可能是由于宿主中吞噬体成熟过程的重新参与所致。这些总体数据表明，几种共生藻细胞去除机制共存，并且压力源可以激活这些途径中的一种或多种，具体取决于压力类型、强度或持续时间。
Cnidarian-dinoflagellate symbiosis disruption and subsequent bleaching are major concerns, especially regarding their ecological consequences on coral reefs and temperate coralligenous communities. Cnidarian bleaching is caused by a variety of environmental stressors, such as elevated seawater temperature associated with global climate change, and by pollutants, such as herbicides and metals. Several cellular events have been described to explain symbiosis dysfunction and bleaching. Excess or damaged Symbiodinium symbionts are removed through a variety of mechanisms, including exocytosis, apoptosis, necrosis and autophagy. However, few studies have compared in the same species the relative involvement of these mechanisms, according to the stress inducing the bleaching. In this study, we used two different treatments -temperature and menthol-to induce bleaching in the sea anemone Anemonia viridis. By monitoring the ultrastructural tissue modifications, in control specimens we observed a basal rate of in situ symbiont digestion -or symbiophagy-induced by starvation. Symbiophagy was strongly induced in menthol-treated specimens and was the main cellular process of bleaching, whereas apoptosis and necrosis predominated in hyperthermal-induced bleaching. These results suggested a host effect through autophagy in menthol-treated specimens. These observations also suggested that symbiont removal may result from reengagement of the phagosomal maturation process in the host. These overall data demonstrate that several Symbiodinium cell removal mechanisms coexist and that stressors can activate one or more of these pathways, depending on the stress type, intensity or duration.