THE ESTABLISHMENT OF INTRACELLULAR SYMBIOSIS IN AN ANCESTOR OF COCKROACHES AND TERMITES
THE ESTABLISHMENT OF INTRACELLULAR SYMBIOSIS IN AN ANCESTOR OF COCKROACHES AND TERMITES
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DOI：
10.1098/rspb.1995.0043
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发表时间：
1995-03-22
影响因子：
4.7
通讯作者：
SACCHI, L
中科院分区：
文献类型：
--
作者：
BANDI, C;SIRONI, M;SACCHI, L
迄今为止检查的所有蟑螂都被发现在脂肪体的特殊细胞中含有细菌内共生体，而达尔文乳白蚁是目前已知的唯一含有细胞内共生体的白蚁。这些细菌的定位和传播方式惊人地相似，但迄今为止尚未发表有关它们的系统发育关系的数据。为了解决这个问题，从编码达尔文氏菌内共生体小亚基核糖体 RNA 的基因中获得了分子序列数据，并将其与从七种蟑螂的内共生体中获得的数据进行了比较。分子系统发育分析明确地将所有这些细菌归入黄杆菌-类杆菌中，表明达尔文氏菌的内共生体是所检查的蟑螂内共生体的姐妹群。此外，内共生体之间的核苷酸分歧似乎与宿主进化的古生物学数据一致。这些结果支持了之前的说法，即最初的感染发生在蟑螂和白蚁的共同祖先中。随后，除了产生达尔文白蚁的白蚁谱系外，所有白蚁谱系都应该发生内共生体的丧失。
All cockroaches examined so far have been found to harbour a bacterial endosymbiont in specialized cells of the fat body, whereas Mastotermes darwiniensis is the only termite currently known to harbour an intracellular symbiont. The localization and mode of transmission of these bacteria are surprisingly similar, but so far no data have been published on their phylogenetic relationships. To address this issue, molecular sequence data were obtained from the genes encoding the small subunit ribosomal RNA of the M. darwiniensis endosymbiont, and compared with those obtained from endosymbionts of seven species of cockroaches. Molecular phylogenetic analysis unambiguously placed all these bacteria among the flavobacteria-bacteroides, indicating that the endosymbiont of M. darwiniensis is the sister group to the cockroach endosymbionts examined. Additionally, nucleotide divergence between the endosymbionts appears to be congruent with the palaeontological data on the hosts's evolution. These results support previous claims that the original infection occurred in an ancestor common to cockroaches and termites. A loss of endosymbionts should subsequently have occurred in all termite lineages, except that which gave rise to M. darwiniensis.