关键词: 线粒体DNA, 蓖麻蚕, COX3基因, 分子进化

Abstract:

The cytochrome oxidase subunit Ⅲ gene (COX3), tRNA-Gly gene and partial ND3 gene of the eri silkworm, Samia cynthia ricini, were sequenced. The open reading frame of COX3 gene contains 789 nucleotides, encoding a putative protein of 262 amino acids. Comparison of the amino acid homology with COX3 genes of other eleven arthropods was made.The results showed that the conservation of C′ termination was higher than N'- termination in COX3, and there were two conservative regions in C'-termination of COX3. The COX3 gene of mtDNA in the eri silkworm was most closely related to that of the silkworm Bombyx mori, with the homology of 80.2% nucleotide and 85.6% amino acid respectively. Based on the alignment of amino acid sequences deduced from the COX3 genes, a phylogenetic tree of the twelve invertebrates was constructed. It was proposed that when the molecular evolution is analysed based on mitochondrial genetic sequences, the reproduction pattern and ecological characteristics should be considered.

Key words: mitochondrial DNA, Samia cynthia ricini, COX3 gene, molecular evolution