MOLECULAR-GENETIC ANALYSIS OF RIBOSOMAL GENE POLYMORPHISM IN SILKWORM BOMBYX-MORI L GENOME

Organization of ribosomal genes in genomes of Bombyx mori L. strains was studied with the use of genomic blot analysis. It was revealed that the rDNA repeats have length heterogeneity, due to the presence of R1Bm and R2Bm elements in the 28S rDNA coding region. The content of rDNA repeals with the type R1 insertion varied in different strains from 3 to 25%. The content of rDNA repeats with the type R2 insertion is equal in all strains and corresponds to 8-10%. It was found that the rDNA repeats with the R1Bm element present both in male and female silkworm individuals. From this fact we made conclusion that the rDNA genes are localized in one of the silkworm autosomes. Nevertheless, as shown by analysis of 6 strains and their reciprocal hybrids, the amount of rDNA repeats with the R1Bm clement has maternal inheritance. The role of maternal silkworm genotype in somatic chromosome rearrangements of the R1Bm element is under discussion.