[Divergence of unique and repetitive sequences in the genomes of fish].

The sterlet (Acipenser acipenser) genome was compared with the genome of other fishes by molecular hybridization of its fractions. The genomes of all fishes of the family Acipenseridae are represented by the same sets of repetitive and single copy sequences. Single copy sequences contain 1.5-2.7% nucleotide mismatches, and repetitive sequences 0-2.6%, so the divergency rate of single copy sequences in this family is higher that of the repetitive sequences. The rates of evolution of the repetitive sequences with different intragenomic divergency are the same. The great similarity in the structure of genomes of Acipenseridae is the molecular basis for the formation of vital fertile hybrids between these fishes. The genomes of Acipenseridae contain some sequences homologous to teleostean and chondrostean fishes DNA. These sequences are 5% of single copy and 10-25% of repetitive sequences and are the most conservative sequences in the fishes genomes.