Apoptosis as a post-phagocytic winnowing mechanism in a coral-dinoflagellate mutualism
Apoptosis as a post-phagocytic winnowing mechanism in a coral-dinoflagellate mutualism
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DOI：
10.1111/j.1462-2920.2008.01774.x
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发表时间：
2009-01-01
影响因子：
5.1
通讯作者：
Weis, Virginia M.
中科院分区：
文献类型：
--
作者：
Dunn, Simon R.;Weis, Virginia M.
本研究的目的是检测细胞凋亡作为后吞噬机制的共生体选择在发病的共生在幼体的石珊瑚真菌scutaria。幼虫感染三种共生甲藻类型之一：新鲜分离的同源ITS型C1f从成人F。Scutaria，来自Montipora capitata的异源C31，已知不能成功地定殖F. Scutaria幼虫，以及共生海葵Aiptasia spp.通过激活凋亡特异性的半胱天冬酶来检测细胞凋亡。通过切割特定的荧光团并用共聚焦显微镜检测来原位测量胱天蛋白酶活性。感染后6 h，与感染C1f或B1型的幼虫相比，C31感染的幼虫胃胚层细胞中caspase活化显著增加。与感染C31的对照幼虫相比，感染后24小时感染率降低，当C31感染的幼虫与广泛的半胱天冬酶抑制剂一起孵育时，感染C31的幼虫的百分比并没有随着时间的推移而显著降低。这表明在未处理的C31感染的幼虫中观察到的感染成功率的降低可以通过抑制半胱天冬酶和细胞凋亡来挽救。这表明存在吞噬后识别机制。与C31感染的幼虫相比，感染新鲜分离的B1的幼虫随着时间的推移保留感染成功，这表明异源藻类之间存在宿主歧视。与通才异源类型如进化枝B1相比，高度特异性异源共生体类型如C31可能更容易引发这种吞噬后应答。
This study was aimed at detecting apoptosis as a post-phagocytic mechanism of symbiont selection during the onset of symbiosis in larvae of the scleractinian coral Fungia scutaria. Larvae were infected with one of three Symbiodinium types: freshly isolated homologous ITS-type C1f from adult F. scutaria, heterologous C31 from adult Montipora capitata, known to be unable to successfully colonize F. scutaria larvae, and type B1 from the symbiotic sea anemone Aiptasia spp. Apoptosis was detected by the activation of caspases, enzymes specific to apoptosis. Caspase activity was measured in situ by cleavage of a specific fluorophore and detection with confocal microscopy. At 6 h post infection, there was a significant increase in caspase activation in gastrodermal cells in C31-infected larvae, compared with larvae infected with C1f or B1 types. Compared with control larvae infected with C31, which had decreased infection rates present by 24 h post infection, when C31-infected larvae were incubated with a broad-scale caspase inhibitor, the per cent of larvae infected with C31 did not significantly decrease over time. This indicates that the reduction in infection success observed in untreated C31-infected larvae can be rescued with inhibition of caspases and apoptosis. This suggests the presence of a post-phagocytic recognition mechanism. Larvae infected with freshly isolated B1 retained infection success over time compared with C31-infected larvae, suggesting that there is host discrimination between heterologous algae. Initiation of this post-phagocytic response may occur more readily with a highly specific heterologous symbiont type such as C31, compared with a generalist heterologous type such as clade B1.