A novel tripartite structure comprising a mariner-like element and two additional retrotransposons found in the Bombyx mori genome

作者：Nakajima Y; Hashido K; Tsuchida K; Takada N; Shiino T; Maekawa H^*

来源：Journal of Molecular Evolution, 1999, 48(5): 577-585.

DOI：10.1007/PL00006500

• silkworm
• Bombyx mori
• transposon
• mariner-like element
• retrotransposon
• BMC1
• L1Bm
• LINE
• retrotransposition
• SINE

A clone of a DNA-mediated mobile element (transposon) corresponding to a mariner-like element (MLE) was obtained by carrying out the polymerase chain reaction with genomic DNA of Bombyx mori using a Hyalophora cecropia MLE sequence as a primer, This clone had a size of about 4.2 kb and, after sequencing, was found to contain an RNA-mediated, shorter retrotransposon named L1Bm, which was in turn integrated with a much longer retrotransposon named BMC1, Thus, the mobile elements made a novel tripartite structure. The BMC1 and L1Bm moieties of the composite structure each contained a 63-bp conserved sequence which was subsequently found to be highly conserved in all BMC1 and L1Bm elements registered so far. We propose that the 63-bp stretch may be a recognition site for a retrotransposition mechanism conducted by a reverse transcriptase and an endonuclease complex. On the basis of this inference, we propose a model that predicts how different types of BMC1 and L1Bm elements are dispersed in the genome. In addition, a phylogenetic tree made from the current and extant BMC1 and L1Bm sequences indicated that these elements can be classified into Subfamilies I and II.

• 出版日期1999-5