Genetic differentiation among isolates of Teredinibacter turnerae, a widely occurring intracellular endosymbiont of shipworms.
Genetic differentiation among isolates of Teredinibacter turnerae, a widely occurring intracellular endosymbiont of shipworms.
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DOI：
10.1111/mec.12667
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发表时间：
2014-03
影响因子：
4.9
通讯作者：
Distel DL
中科院分区：
文献类型：
--
作者：
Altamia MA;Wood N;Fung JM;Dedrick S;Linton EW;Concepcion GP;Haygood MG;Distel DL
teredinibacterturnerae是teredididae科木食双壳类（船虫）中可培养的细胞内共生体。虽然已经从许多地点收集的许多船虫分类群中分离出了turn T.，但在其寄主的分类和地理范围内，对这一共生物种的遗传多样性尚未进行系统的探索。共生体的传播方式尚不清楚。本文研究了从大西洋、太平洋和印度洋的15个地点收集的13种船虫中培养的25株转角T.菌株的6个基因片段（16S rRNA、gyrB、sseA、recA、rpoB和celAB）的序列多样性。虽然16S rRNA序列在所有检测的分离株中几乎不变（最大两两差异<0.26%），但在所检测的蛋白质编码位点之间的差异更大（平均两两差异为2.2-5.9%）。基于每个蛋白质编码位点的系统发育分析将25个分离株区分为两个不同且支持良好的分支。除了5个例外，每个分离株的进化系归属都是通过分析5个蛋白质编码位点的等位基因来支持的。这些例外包括：(1)两个分离株（PMS-535T.S.1b）中celAB和gyrB位点的推定重组等位基因。(2)在三个分离株（T8412、T8503和T8513）中，可能存在影响第二个基因座（recA）的侧向基因转移事件。这些结果表明，turn T.分离株并不代表一个同质的全球种群。相反，它们表明两种谱系的出现，尽管不同，但可能彼此之间以及与其他细菌物种之间经历了某种程度的基因交换。
Teredinibacter turnerae is a cultivable intracellular endosymbiont of xylotrophic (wood-feeding) bivalves of the Family Teredinidae (shipworms). Although T. turnerae has been isolated from many shipworm taxa collected in many locations, no systematic effort has been made to explore genetic diversity within this symbiont species across the taxonomic and geographic range of its hosts. The mode of symbiont transmission is unknown. Here we examine sequence diversity in fragments of six genes (16S rRNA, gyrB, sseA, recA, rpoB, and celAB) among 25 isolates of T. turnerae cultured from 13 shipworm species collected in 15 locations in the Atlantic, Pacific and Indian Oceans. While 16S rRNA sequences are nearly invariant among all examined isolates (maximum pairwise difference <0.26%) variation among examined protein coding loci is greater (mean pairwise difference 2.2-5.9%). Phylogenetic analyses based on each protein-coding locus differentiate the 25 isolates into two distinct and well-supported clades. With five exceptions, clade assignments for each isolate were supported by analysis of alleles of each of the five protein coding loci. These exceptions include (1) putative recombinant alleles of the celAB and gyrB loci in two isolates (PMS-535T.S.1b.3 and T8510), suggesting homologous recombination between members of the two clades, and (2) evidence for a putative lateral gene transfer event affecting a second locus (recA) in three isolates (T8412, T8503 and T8513). These results demonstrate that T. turnerae isolates do not represent a homogeneous global population. Instead they indicate the emergence of two lineages that, although distinct, likely experience some level of genetic exchange with each other and with other bacterial species.