Graduated School of Sciences, Kyushu University, Hakozaki 6-10-1, Higashi-Ku, Fukuoka 812-8581, Japan.
Mol Phylogenet Evol. 2013 Mar;66(3):906-14. doi: 10.1016/j.ympev.2012.11.018. Epub 2012 Dec 4.
Although many physiological studies have been reported on the symbiosis between hydra and green algae, very little information from a molecular phylogenetic aspect of symbiosis is available. In order to understand the origin and evolution of symbiosis between the two organisms, we compared the phylogenetic relationships among symbiotic green algae with the phylogenetic relationships among host hydra strains. To do so, we reconstructed molecular phylogenetic trees of several strains of symbiotic chlorella harbored in the endodermal epithelial cells of viridissima group hydra strains and investigated their congruence with the molecular phylogenetic trees of the host hydra strains. To examine the species specificity between the host and the symbiont with respect to the genetic distance, we also tried to introduce chlorella strains into two aposymbiotic strains of viridissima group hydra in which symbiotic chlorella had been eliminated in advance. We discussed the origin and history of symbiosis between hydra and green algae based on the analysis.
尽管已有许多关于水螅和绿藻共生的生理学研究报告，但从共生的分子系统发育角度来看，相关信息却非常有限。为了了解两者共生的起源和进化，我们比较了共生绿藻的系统发育关系与宿主水螅菌株的系统发育关系。为此，我们构建了栖息在水螅属绿藻组水螅菌株内胚层上皮细胞中的几种共生绿藻的分子系统发育树，并研究了它们与宿主水螅菌株的分子系统发育树的一致性。为了研究宿主和共生体之间在遗传距离上的物种特异性，我们还试图将绿藻菌株引入事先消除共生绿藻的两个水螅属绿藻组的无共生体水螅菌株中。我们根据分析讨论了水螅和绿藻共生的起源和历史。
