Allelic variability in the third intron of the fibroin light chain gene in Bombyx mori (Lepidoptera: Bombycidae).

Conformation-sensitive gel electrophoresis is a useful method for identifying allele polymorphism; it provides co-dominant molecular markers. Using this method, we identified genetic variability in the third intron of the fibroin light chain gene, fib-L, in six Bombyx mori strains. Only Chinese C21A strain did not demonstrate allelic alterations, showing only homoduplex DNA molecules. We found distinct heteroduplex profiles in the Japanese HAA, M12B and M19-2 and the Chinese C25B and C24-2 strains. Analysis with restriction endonuclease fingerprinting conformation-sensitive gel electrophoresis demonstrated the potential of this method for the identification of allelic variability in B. mori; this was confirmed by cloning and sequencing the different alleles. The main alteration was a 12-bp deletion in two alleles of the C24-2 strain and one allele of the HAA strain; this deletion results in specific heteroduplex DNA molecule profiles.