BSP FAMILY OF TANDEMLY REPEATED DNA-SEQUENCES OF BAIKAL COTTOID FISHES (COTTOIDEA)

Data on a new family of highly repetitive, tandemly organized DNA sequ ences isolated by FAG electrophoresis from BspMII hydrolysates of DNA of the Baikal cottoid fishes (Cottoidea) are discussed. The repeats ar e able to form stable secondary structures in vitro. By cloning and se quencing of three repeats from B. nikolskii and P. kneri their lengths were estimated at 238, 154, and 123 bp; all these repeats had highly homologous flanking regions 53 bp and 63 bp long. It was suggested tha t the shorter repeat species (154 and 123 bp) originate from the longe r one (238 bp) by deletion of a part of its inner sequence. An RNA pol ymerase III promoter sequence was found in one of the elements of 238 bp repeat; the element could have emerged from one of the genes coding for tRNA. The usefulness of BspMII repeats as phylogenetic markers in the study of the Cottoidea evolution is evaluated.