State Key Laboratory of Rice Biology and Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, China.
BMC Genomics. 2011 May 19;12:248. doi: 10.1186/1471-2164-12-248.
The domesticated silkworm, Bombyx mori, is the model insect for the order Lepidoptera, has economically important values, and has gained some representative behavioral characteristics compared to its wild ancestor. The genome of B. mori has been fully sequenced while function analysis of BmChi-h and BmSuc1 genes revealed that horizontal gene transfer (HGT) maybe bestow a clear selective advantage to B. mori. However, the role of HGT in the evolutionary history of B. mori is largely unexplored. In this study, we compare the whole genome of B. mori with those of 382 prokaryotic and eukaryotic species to investigate the potential HGTs.
Ten candidate HGT events were defined in B. mori by comprehensive sequence analysis using Maximum Likelihood and Bayesian method combining with EST checking. Phylogenetic analysis of the candidate HGT genes suggested that one HGT was plant-to- B. mori transfer while nine were bacteria-to- B. mori transfer. Furthermore, functional analysis based on expression, coexpression and related literature searching revealed that several HGT candidate genes have added important characters, such as resistance to pathogen, to B. mori.
Results from this study clearly demonstrated that HGTs play an important role in the evolution of B. mori although the number of HGT events in B. mori is in general smaller than those of microbes and other insects. In particular, interdomain HGTs in B. mori may give rise to functional, persistent, and possibly evolutionarily significant new genes.
家蚕是鳞翅目昆虫的模式昆虫，具有重要的经济价值，相对于其野生祖先具有一些代表性的行为特征。B. mori 的基因组已经完全测序，而 BmChi-h 和 BmSuc1 基因的功能分析表明，水平基因转移（HGT）可能赋予 B. mori 明显的选择优势。然而，HGT 在 B. mori 进化历史中的作用在很大程度上尚未得到探索。在本研究中，我们将 B. mori 的全基因组与 382 种原核和真核物种的基因组进行比较，以研究潜在的 HGT。
通过使用最大似然法和贝叶斯法结合 EST 检查的综合序列分析，我们在 B. mori 中定义了十个候选 HGT 事件。候选 HGT 基因的系统发育分析表明，一个 HGT 是植物到 B. mori 的转移，而九个是细菌到 B. mori 的转移。此外，基于表达、共表达和相关文献搜索的功能分析表明，几个 HGT 候选基因赋予了 B. mori 重要的特征，如对病原体的抗性。
本研究的结果清楚地表明，尽管 B. mori 中的 HGT 事件数量总体上小于微生物和其他昆虫，但 HGT 在 B. mori 的进化中发挥了重要作用。特别是，B. mori 中的跨域 HGT 可能产生功能持久且可能具有进化意义的新基因。
