[Comparative analysis of B1- and B2-like repetitive sequences in DNA from different organisms]

Sequences homologous to short repeated elements of the mouse genome, B1 and B2, were detected in DNA of different organisms by dot-hybridization. The sequences B1 and B2 hybridized most efficiently with DNA of Myomorpha rodents and primates. The hybridization was also observed with DNA of all other eukaryotes studied, however, it is probably caused by an existence of short homologies with the B1 and B2 sequences only. The effective hybridization of the B1 sequence with DNA of primates is apparently explained by a presence of numerous copies of Alu sequence in their genomes. A repeated sequence of the human DNA that is able to hybridize with B2 sequence was cloned. It was designated as HsB2 sequence. There are about 5000 copies of this sequence in the human genome. To estimate the degree of homology, the melting temperature of hybrids of sequences B1 and B2 with DNA of rodents and some other mammals was measured. It was found that the degree of homology of B2 sequence (but not B1) correlated well with the phylogenetic relationship of the organisms. Perhaps, the difference of evolution of these sequences results from their structural and functional peculiarities.