Uniform distribution of satellite DNA variants on the chromosomes of tenebrionid species Alphitobius diaperinus and Tenebrio molitor.

The chromosomes of tenebrionid species Alphitobius diaperinus contain large blocks of pericentromerically located constitutive heterochromatin, as revealed by C-banding procedure. As previously reported, satellite DNA of this species is composed of two related monomeric units organized in three satellite subfamilies. In order to analyze the chromosomal location of the satellite DNA and the distribution of monomeric variants within it, and compare it with the distribution of monomer variants in Tenebrio molitor satellite DNA, the methods of in situ hybridization and restriction enzyme/nick translation were performed. Fluorescent in situ hybridization with the entire satellite DNA reveals the pericentromerically located signals on all chromosomes of the complement, coinciding with heterochromatic blocks. Results of fluorescent in situ hybridization with particular monomeric variants and of in situ restriction enzyme/nick translation show that monomeric variants are homogeneously dispersed within the entire satellite DNA. The spreading of satellite monomeric variants of the related species T. molitor within the pericentromeric heterochromatin of the entire complement, is demonstrated using the method of in situ restriction enzyme/nick translation. Although the complexity of organization of satellite DNAs is quite distinct in these two species, obtained results suggest similar efficiency of mechanisms of spreading and homogenization resulting in random chromosomal distribution of their satellite variants.