基因水平转移的评判方法和转移方式研究进展

基因水平转移是不同物种之间或细胞器间基因的交流。基因水平转移现象在原核生物中普遍存在, 在真核生物中近年来也发现了众多例证, 说明水平转移是生物界的普遍现象。文章着重对基因水平转移的概念、评判基因水平转移的标准, 水平转移的特点和转移方式, 以及基因水平转移对基因组进化的作用等方面的研究进展进行了综述。在已有的基因水平转移研究中进化树分析法、碱基组成分析法、选择压力分析法、内含子分析法、特殊序列分析法和核苷酸组成偏向性分析法等几种是常用的方法; 转座序列是生物中最易于发生水平转移的基因类型；原核生物基因水平转移的主要方式有转化、接合和转导, 真核生物中水平转移发生方式尚不清楚。基因水平转移在基因、基因组和生物进化中有着其独特的作用。

Methods for the identification of horizontal gene transfer (HGT) events and progress in related fields

Horizontal gene transfer is the gene exchange between different organisms or different organelles, which occurs frequently in prokaryotes. Many newly identified horizontal transfer events in eukaryotes indicates that it is a common phenomenon in all organisms. This paper describes the concept of horizontal gene transfer, the standard for judging a horizontal gene transfer events, the character, the mode, the way of horizontal gene transfer, and its impact on gene and genome evolution. The analyses of phylogenetic tree, base composition, selection pressure, intron sequence comparison, inserted special sequence, and biased nucleotide substitution are the most common methods used in previous researches. Evidence accumulated demonstrated that transposable sequences are most likely undergoing horizontal transferring. Transformation, conjugation, and transduction are the main forms of horizontal gene transfer in prokaryotes, but no clear clue was related with the mechanism of horizontal gene transfer in eukaryotes. Horizontal gene transfer plays a special role in genetic, ge-nomic, and the biological evolution.