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

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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.