Sequence comparison of MLEs of some lepidopteran insects inhabiting in east Asia isolated by PCR method using the inverted terminal repeat of Cecropia MLE and the analysis of transposase activity of MLE isolated from Attacus atlas of Yonaguni island by th

利用水母夜蛾MLE的反向末端重复序列(ITR)，从几种亚洲昆虫(主要是鳞翅目昆虫)和无脊椎动物中分离到水手样元件(MLEs)。在离散的1.3kbp附近，检测到了一些标本的单条带，预计含有全长的MLEs和来自其他昆虫的不同长度的片段。从居住在日本周边相对较近地区的物种中分离到的MLEs全长高度相似，被归入Cecropia MLEs亚家族，其中一些MLEs具有转座酶的完整ORF编码。这似乎表明，最近甚至在系统发育较远的生物之间也发生了MLE的水平转移，这些MLE即使现在也可能有水平转移的能力。从家蚕(n=28)和野桑蚕(n-27)分离得到的一些明显不活跃的MLE位于天牛亚科水平群以外的其他系统发育群中，这表明在野桑蚕基因组分离之前，这种类型的MLE已经插入到这些物种的古老基因组中。中国的一个个体有一条4.2kBP的离散条带，其中包含一个Bmc1和L1Bm反转录转座子，这是在几乎所有家蚕品种和品系中都检测到的唯一片段(该单位的最大似然序列被命名为BmTNML，Nakajima等，1999)。因此，家蚕基因组分离后与家蚕杂交可自发合成4.2-kbp的转座酶单位。将从家蚕中分离到的具有完整转座酶开放阅读框架的水手序列的转座酶片段克隆到表达载体pENTR11中。对其在E.coll基因组和家蚕培养细胞中的转座活性的分析目前仍在进行中。

Mariner-like elements(MLEs) were isolated from several Asian insects(mainly lepidopteran insects) and invertebrates using the inverted terminal repeat(ITR) of the Hyalophora cecropia MLE as PCR primers. Around the discrete 1.3 kbp single bands from some specimens expected to contain the full-length of MLEs and various lengths of the fragments from other insects were detected. The full-length of MLEs isolated from the species inhabiting in relatively close regions around Japan were highly similar to each other classifying into the Cecropia MLEs sub family and some of them had the complete ORFs coding for transposase. This seem to indicate that the horizontal transfer of MLEs has taken place even among phylogenetically remote organisms recently and these MLEs might have the ability to transfer horizontally even now. Some of the clearly inactive MLEs making a complex isolated from Bombyx mori (n=28) and B.mandarina(n-27) were situated in other phylogenetic group than the horizontally group of Cecropia subfamily implies that this type of MLEs had inserted into the ancient genome of these species before the genomic segregation of B.mandarina between the Japanese/Korean types(n=27) and the Chinese/Korean types(n=28). One individual from China had a discrete 4.2-kbp band containing a BMCl and LlBm retrotransposon, which is a unique fragment detected in almost all of the silkworm races and strains(the MLE of this unit was named as BmTNML, Nakajima et al.,1999). Thus, the 4.2-kbp unit might be made spontaneously by crossing with B.mori after the segregation of B.mori genome.The transposase region from the full length of mariner sequence isolated from Attacus atlas, which had the complete ORF for transposase, was cloned into the expression vector pENTR11. And the analyses of its transposition activity in the genome of E.coll and in the cultured cell of B.mori are still progressing now.