Revised Systematics of Holospora-Like Bacteria and Characterization of "Candidatus Gortzia infectiva", a Novel Macronuclear Symbiont of Paramecium jenningsi
Revised Systematics of Holospora-Like Bacteria and Characterization of "Candidatus Gortzia infectiva", a Novel Macronuclear Symbiont of Paramecium jenningsi
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DOI：
10.1007/s00248-012-0110-2
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发表时间：
2013-01-01
影响因子：
3.6
通讯作者：
Petroni, Giulio
中科院分区：
文献类型：
--
作者：
Boscaro, Vittorio;Fokin, Sergei I.;Petroni, Giulio
全孢子虫属（立克次体目）包括纤毛草履虫的高度感染性核共生体，具有独特的形态和生活史。到目前为止，已经描述了9个物种，但其中大多数缺乏分子特征。在这项研究中，我们的特点是一种新的Holospora样细菌（HLB）生活在大核草履虫jenningsi人口。对该菌进行了形态学和超微结构的研究，并对其生活史和感染能力进行了描述。我们还获得了它的16 SrRNA基因序列，并研制了特异性探针用于荧光原位杂交实验。根据其独特的生物学特性和与其他细菌的DNA序列相似性较低的特点，建立了一个新的分类群-。基于16 S rRNA基因序列的立克次体目的遗传学已经被推断出来，在现有的数据中增加了新细菌的序列和两种全孢菌属物种（Holospora obtusa和Holospora undulata）的序列。我们的系统发育分析提供了分子支持的单系性HLBs，并显示了一个可能的模式，他们的一些功能的进化。我们建议在全孢菌科中仅将HLB分类，排除其他更远的亲缘关系和表型不同的草履虫内共生体。
The genus Holospora (Rickettsiales) includes highly infectious nuclear symbionts of the ciliate Paramecium with unique morphology and life cycle. To date, nine species have been described, but a molecular characterization is lacking for most of them. In this study, we have characterized a novel Holospora-like bacterium (HLB) living in the macronuclei of a Paramecium jenningsi population. This bacterium was morphologically and ultrastructurally investigated in detail, and its life cycle and infection capabilities were described. We also obtained its 16S rRNA gene sequence and developed a specific probe for fluorescence in situ hybridization experiments. A new taxon, "Candidatus Gortzia infectiva", was established for this HLB according to its unique characteristics and the relatively low DNA sequence similarities shared with other bacteria. The phylogeny of the order Rickettsiales based on 16S rRNA gene sequences has been inferred, adding to the available data the sequence of the novel bacterium and those of two Holospora species (Holospora obtusa and Holospora undulata) characterized for the purpose. Our phylogenetic analysis provided molecular support for the monophyly of HLBs and showed a possible pattern of evolution for some of their features. We suggested to classify inside the family Holosporaceae only HLBs, excluding other more distantly related and phenotypically different Paramecium endosymbionts.