Moran Nancy A, Tran Phat, Gerardo Nicole M
Biological Sciences West 310, Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA.
Appl Environ Microbiol. 2005 Dec;71(12):8802-10. doi: 10.1128/AEM.71.12.8802-8810.2005.
Several insect groups have obligate, vertically transmitted bacterial symbionts that provision hosts with nutrients that are limiting in the diet. Some of these bacteria have been shown to descend from ancient infections. Here we show that the large group of related insects including cicadas, leafhoppers, treehoppers, spittlebugs, and planthoppers host a distinct clade of bacterial symbionts. This newly described symbiont lineage belongs to the phylum Bacteroidetes. Analyses of 16S rRNA genes indicate that the symbiont phylogeny is completely congruent with the phylogeny of insect hosts as currently known. These results support the ancient acquisition of a symbiont by a shared ancestor of these insects, dating the original infection to at least 260 million years ago. As visualized in a species of spittlebug (Cercopoidea) and in a species of sharpshooter (Cicadellinae), the symbionts have extraordinarily large cells with an elongate shape, often more than 30 mum in length; in situ hybridizations verify that these correspond to the phylum Bacteroidetes. "Candidatus Sulcia muelleri" is proposed as the name of the new symbiont.
几个昆虫类群拥有专性的、垂直传播的细菌共生体，这些共生体为宿主提供饮食中有限的营养物质。其中一些细菌已被证明源自古代感染。在这里，我们表明包括蝉、叶蝉、角蝉、沫蝉和飞虱在内的一大类相关昆虫宿主着一个独特的细菌共生体分支。这个新描述的共生体谱系属于拟杆菌门。对16S rRNA基因的分析表明，共生体系统发育与目前已知的昆虫宿主系统发育完全一致。这些结果支持了这些昆虫的共同祖先在古代获得了一种共生体，将最初的感染追溯到至少2.6亿年前。如在一种沫蝉（沫蝉总科）和一种叶蝉（叶蝉亚科）中所见，共生体具有异常大的细胞，呈细长形，长度通常超过30微米；原位杂交证实这些对应于拟杆菌门。提议将“候选穆勒苏尔西亚菌（Candidatus Sulcia muelleri）”作为新共生体的名称。
