Genome analysis of Elysia chlorotica Egg DNA provides no evidence for horizontal gene transfer into the germ line of this Kleptoplastic Mollusc.
Genome analysis of Elysia chlorotica Egg DNA provides no evidence for horizontal gene transfer into the germ line of this Kleptoplastic Mollusc.
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DOI：
10.1093/molbev/mst084
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发表时间：
2013-08
影响因子：
10.7
通讯作者：
Rumpho ME
中科院分区：
文献类型：
--
作者：
Bhattacharya D;Pelletreau KN;Price DC;Sarver KE;Rumpho ME
海蛞蝓为研究复杂多细胞宿主中新功能（光合作用）的进化提供了独特的机会。 Elysia chlorotica 从其异质藻类猎物 Vaucheria litorea 中收获质体（无细胞核）。 “被盗”的质体在消化道细胞中保存数月，对于动物发育至关重要。这种海蛞蝓长期维持光合作用的基础被认为是通过从藻类细胞核到动物细胞核的广泛水平基因转移（HGT）来解释的，随后藻类基因在肠道中表达以提供必需的质体蛋白。对目标基因和蛋白质的早期研究支持 HGT 假说，但最近的全基因组数据提供了相互矛盾的结果。在这里，我们从 E. greentica 种系（卵 DNA）和 V. litorea 中生成了重要的基因组数据，以检验 HGT 假设。我们的综合分析未能提供海藻衍生的 HGT 进入海蛞蝓种系的证据。然而，对不同绿藻个体的基因组 DNA 和 cDNA 进行的聚合酶链式反应分析表明，成体蛞蝓中存在藻类核基因（或基因片段）。我们认为这些核酸可能源自和/或存在于染色体外 DNA 中，动物通过与藻类接触而获得这些 DNA。这些数据解决了一个长期存在的问题，并表明 HGT 并不是绿叶藻光合作用长期维持的主要原因。因此，海蛞蝓的光合作用以迄今无法解释的方式持续进行，似乎不会通过引入数十种外来基因而危及动物种系。
The sea slug Elysia chlorotica offers a unique opportunity to study the evolution of a novel function (photosynthesis) in a complex multicellular host. Elysia chlorotica harvests plastids (absent of nuclei) from its heterokont algal prey, Vaucheria litorea. The “stolen” plastids are maintained for several months in cells of the digestive tract and are essential for animal development. The basis of long-term maintenance of photosynthesis in this sea slug was thought to be explained by extensive horizontal gene transfer (HGT) from the nucleus of the alga to the animal nucleus, followed by expression of algal genes in the gut to provide essential plastid-destined proteins. Early studies of target genes and proteins supported the HGT hypothesis, but more recent genome-wide data provide conflicting results. Here, we generated significant genome data from the E. chlorotica germ line (egg DNA) and from V. litorea to test the HGT hypothesis. Our comprehensive analyses fail to provide evidence for alga-derived HGT into the germ line of the sea slug. Polymerase chain reaction analyses of genomic DNA and cDNA from different individual E. chlorotica suggest, however, that algal nuclear genes (or gene fragments) are present in the adult slug. We suggest that these nucleic acids may derive from and/or reside in extrachromosomal DNAs that are made available to the animal through contact with the alga. These data resolve a long-standing issue and suggest that HGT is not the primary reason underlying long-term maintenance of photosynthesis in E. chlorotica. Therefore, sea slug photosynthesis is sustained in as yet unexplained ways that do not appear to endanger the animal germ line through the introduction of dozens of foreign genes.
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影响因子：
3.7
作者：
Maeda T;Hirose E;Chikaraishi Y;Kawato M;Takishita K;Yoshida T;Verbruggen H;Tanaka J;Shimamura S;Takaki Y;Tsuchiya M;Iwai K;Maruyama T
通讯作者：
Maruyama T
影响因子：
9.2
作者：
Chan, Cheong Xin;Yang, Eun Chan;Bhattacharya, Debashish
通讯作者：
Bhattacharya, Debashish
影响因子：
2.4
作者：
Evertsen, Jussi;Burghardt, Ingo;Waegele, Heike
通讯作者：
Waegele, Heike
影响因子：
2.5
作者：
Pelletreau, Karen N.;Worful, Jared M.;Rumpho, Mary E.
通讯作者：
Rumpho, Mary E.
影响因子：
7.4
作者：
Pelletreau, Karen N.;Bhattacharya, Debashish;Rumpho, Mary E.
通讯作者：
Rumpho, Mary E.