Nuclear mitochondrial DNA pseudogenes in the genome of the silkworm, Bombyx mori

Abstract

To understand the types of mitochondrial deoxyribonucleic acid (mtDNA) pseudogenes in the genome of the silkworm Bombyx mori L. (Lepidoptera: Bombycidae) and to determine the origin of the B. mori, the mtDNA of the wild silkworm, Bombyx mandarina Morre was sequenced. Several fragments from the B. mori genome database were obtained with varying degrees of homology toB. mandarina mtDNA by sequence alignment between the B. mori genome and B. mandarinamtDNAs. The results showed that in the B. mori genome database there are not only mtDNA (Dazao strain) sequence but also pseudogenes derived from B. mandarina mtDNA. There is a potential reverse repeated sequence at the terminal sequence of the pseudogenes, and there are random point mutations and insertion mutations in the pseudogenes sequences. One B. mandarina mtDNA could be repeatedly inserted into different positions within the nuclear genome. Evolutionary analysis indicates that the transfer of mtDNA pseudogenes might have occurred at different points during evolution, some sequences might be transferred after Lepidoptera had formed, and possibly before the families of Lepidoptera were formed. B. mori probably originated from B. mandarina of China. Key words: Bombyx mori, Bombyx mandarina, nDNA, mtDNA, nuclear mitochondrial DNA pseudogenes.