Two Bacterial Genera, Sodalis and Rickettsia, Associated with the Seal Louse Proechinophthirus fluctus (Phthiraptera: Anoplura).
Two Bacterial Genera, Sodalis and Rickettsia, Associated with the Seal Louse Proechinophthirus fluctus (Phthiraptera: Anoplura).
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DOI：
10.1128/aem.00282-16
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发表时间：
2016-06-01
影响因子：
4.4
通讯作者：
Reed DL
中科院分区：
文献类型：
--
作者：
Boyd BM;Allen JM;Koga R;Fukatsu T;Sweet AD;Johnson KP;Reed DL
大约10%到15%的昆虫物种宿主可遗传的共生细菌，称为内共生体。寄生在哺乳动物身上的虱子依靠内共生体来提供它们血液中缺乏的必需维生素。在这里，我们描述了两个细菌联营公司从虱子，原棘眼蝶，这是一个专性的海洋哺乳动物的体外寄生虫。其中之一是一种可遗传的内共生体，与其他哺乳动物虱子的内共生体没有密切关系。更确切地说，它与spittlebugs和咀嚼羽毛的鸟虱相关的Sodalis属的内共生体关系更密切。这种内共生体的定位和垂直传播也更类似于鸟类虱子比其他哺乳动物虱子。内共生体的基因组似乎是降解的共生，但是，它是相当大的比其他哺乳动物虱子内共生体的基因组。这些模式表明，这种Sodalis内共生体可能是最近获得的，取代了现已灭绝的古老内共生体。从同一虱子中，我们还鉴定出一种属于立克次体属的丰富细菌，该细菌与立克次体密切相关，立克次体是一种由蜱传播的人类病原体。在虱子组织中没有观察到明显的立克次氏体细菌群，我们也没有发现任何垂直传播的证据，因此其关联的性质仍然不清楚。 许多昆虫是可遗传的共生细菌的宿主。这些可遗传的细菌已经从许多寄生虱物种中鉴定出来。似乎虱子和细菌之间已经形成了许多新的共生体，新的细菌共生体可能会取代现有的共生体。然而，对寄生在海洋哺乳动物身上的虱子的共生体知之甚少。在这里，我们确定了寄生在北方毛皮海豹虱子的遗传细菌共生体。这种细菌共生体似乎是最近才被虱子获得的。这里报道的发现提供了新的共生体如何形成以及这种生活方式如何塑造共生体基因组的见解。
Roughly 10% to 15% of insect species host heritable symbiotic bacteria known as endosymbionts. The lice parasitizing mammals rely on endosymbionts to provide essential vitamins absent in their blood meals. Here, we describe two bacterial associates from a louse, Proechinophthirus fluctus, which is an obligate ectoparasite of a marine mammal. One of these is a heritable endosymbiont that is not closely related to endosymbionts of other mammalian lice. Rather, it is more closely related to endosymbionts of the genus Sodalis associated with spittlebugs and feather-chewing bird lice. Localization and vertical transmission of this endosymbiont are also more similar to those of bird lice than to those of other mammalian lice. The endosymbiont genome appears to be degrading in symbiosis; however, it is considerably larger than the genomes of other mammalian louse endosymbionts. These patterns suggest the possibility that this Sodalis endosymbiont might be recently acquired, replacing a now-extinct, ancient endosymbiont. From the same lice, we also identified an abundant bacterium belonging to the genus Rickettsia that is closely related to Rickettsia ricketsii, a human pathogen vectored by ticks. No obvious masses of the Rickettsia bacterium were observed in louse tissues, nor did we find any evidence of vertical transmission, so the nature of its association remains unclear. IMPORTANCE Many insects are host to heritable symbiotic bacteria. These heritable bacteria have been identified from numerous species of parasitic lice. It appears that novel symbioses have formed between lice and bacteria many times, with new bacterial symbionts potentially replacing existing ones. However, little was known about the symbionts of lice parasitizing marine mammals. Here, we identified a heritable bacterial symbiont in lice parasitizing northern fur seals. This bacterial symbiont appears to have been recently acquired by the lice. The findings reported here provide insights into how new symbioses form and how this lifestyle is shaping the symbiont genome.