Identification of novel random amplified polymorphic DNAs (RAPDs) on the W chromosome of the domesticated silkworm, Bombyx mori, and the wild silkworm, B-mandarina, and their retrotransposable element-related nucleotide sequences

Genomic DNAs were compared between males and females of the domesticated silkworm, Bombyx nori, strains C108, C137, 5137, p50, and WILD-W (constructed by crossing a wild silkworm, B. mandarina, female with a male of strain C108) by polymerase chain reaction (PCR) with 700 arbitrary 10-mer primers. Four female-specific RAPDs (W-Kabuki, W-Samurai, W-Kamikaze, and W-Yamato) were found. The sex chromosome formulas of B. mori and B. mandarina are ZW (XY) for the female and ZZ (XX) for the male. The four female-specific RAPDs are assumed to be derived from the W chromosome because the other chromosomes are shared by both sexes. A computer search for deduced amino acid sequences of these four RAPDs revealed that all of them showed homology to previously reported amino acid sequences encoded in known retrotransposable elements from various organisms.