Chr.10 To W Translocation Fragment Analysis In Sex-Limited Egg Colour Strains Of Silkworm, Bombyx Mori

Four sex-limited egg colour strains of silkworm L1, L2, P1, P2 were created by Russian scientist Strunnikov with irradiation technology.The Chr.10 fragment of these strains with wild-type egg colour gene(s) was translocated to W chromosome, the normal egg colour gene(s) was mutant to homozygous recessive white colour type. Although these four strains had been reared for 30 years, the gene(s) controling egg colour and the length of translocation chromosomal fragments were still unknown. SSR(simple sequence repeat) marker technology which combined with morphological observation and bioinformatics analysis was used in this experiment, to study the length of translocation fragments from Chr.10 to W chromosomal and polymorphic loci of these four sex-limited egg colour strains L1, L2, P1, P2, silkworm, Bombyx mori. Following results were abtained from this study.By observing the growth of the four sex-limited strains, continuously, we found that sex-limited morphological differences not only presented in egg colour, but also obviously in stripe and colour of wings and eye colour of moths, in sex-limited egg colour strains.As the location of wh3 known from reported paper, the proximal scaffolds of 30 and 44 were downloaded from silkworm genome database, and SSRs were searched from them with a software SSRhunter1.3. Primers were designed with these SSRs to search polymorphic markers between male and female genome DNA of those four sex-limited strains, respectively. Sex-limited markers were confirmed by PCR tests using male and female genome DNA from inbred offspring of those sex-limited strains, hybridized, and backcrossed offspring of sex-limited strains with P50 strain. Results were as follow:length of translocation fragments of these sex-limited strains L1, L2, P1, P2 were 1.9Mbp,2.1Mbp,8.1kbp, and 0.98Mbp approximately, respectively. As blasting with the KAIKObase database,94,107,0, and 6 genes were searched on the fragments of these sex-limited strains L1, L2, P1, P2. Two ABC transporter genes as wh3 and scarlet, which may relate to egg color determination, were confirmed translocated to W chromosome from 10th chromosome in sex-limited strains L2 and P2. The mutant egg colour gene(s) on Chr.10 of L2 and P2 was still not cloned and need further research.Genome DNAs of four sex-limited egg colour strains LI, L2, P1, P2 were also amplified with SSR primers, for checking the genetic relationship of them. Ten lineage-specific markers and twelve systematic correlation makers were got from this test, which could be used for diversity certification of these four sex-limited egg colour strains silkworm, Bombyx mori.