title: Nucleotide sequence variation in mitochondrial COI gene among 147 silkworm (Bombyx mori) strains from Japanese, Chinese, European and moltinism classes.
abstract: We characterized the nucleotide sequences of PCR-amplified mitochondrial COI fragments of 147 silkworm (Bombyx mori) strains that have been maintained in the National Institute of Agrobiological Sciences. Coding sequences (714 bp) of the 147 COI fragments were classified into eight haplotypes based on nucleotide differences at eight segregating sites. No length variation was identified in this region. The 5'-noncoding region showed different features, wherein changes in the number of Ts in the T-stretch, together with two base substitutions, were observed. As a result, the 147 COI noncoding sequences were classified into six haplotypes. Combining the coding and noncoding regions, we identified 14 haplotypes. One of the 14 haplotypes, Hap1A was exclusively abundant in the Japanese native strain class, while this haplotype was less frequent in the other three native strain classes. This finding suggests that the Japanese strain class underwent significant genetic differentiation from the Chinese, European, and moltinism classes, when the each class is regarded as a population. Comparison of the nucleotide sequences to those of B. mandarina (which inhabits Japan) revealed changes that are significantly larger than those within either B. mori or B. mandarina. Furthermore, we detected no common haplotypes between them, which suggests the concept of suppressed gene flow between the two species.
authors.affiliation: Transgenic Silkworm Research Unit, Genetically Modified Organism Research Center, National Institute of Agrobiological Sciences, Ibaraki, Japan. kygnis@affrc.go.jp
authors.forename: Kenji
authors.initials: K
authors.lastname: Yukuhiro
authors.forename: Hideki
authors.initials: H
authors.lastname: Sezutsu
authors.forename: Toshiki
authors.initials: T
authors.lastname: Tamura
authors.forename: Eiichi
authors.initials: E
authors.lastname: Kosegawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Kiuchi
mesh_terms: D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D003576:Electron Transport Complex IV / Q000235:genetics*; D019143:Evolution, Molecular; D014644:Genetic Variation / Q000235:genetics*; D008969:Molecular Sequence Data; D018978:Molting / Q000235:genetics*; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D017931:DNA Primers; D003576:Electron Transport Complex IV