[BspMII-family of tandemly organized DNA sequences of the Baikalian cottoid fish (Cottodei)].

A new family of highly repetitive tandemly arrayed DNA sequences was revealed by electrophoretic analysis of BspMII (T'CCGGA) digest of genomic DNA from Baikalian cottoid fishes. Three such repeats from two species B. nikolskii and P. kneri were cloned and sequenced. The sizes of repeat elements are 238, 154, and 123 bp. All three repeats have highly homologous flanking regions 53 and 63 bp in length. It was shown that chains of DNA repeats had an ability to form stable secondary structures in vitro. It is supposed that shorter repeats (154 and 123 bp) originated from the 238 bp repeat by deletion its central fragments. An element having a the promoter for RNA polymerase III was found within the 238 bp repeat. The origin of this element from one of the tRNA genes is suggested. The possibility of using BspMII repeats as an evolutionary marker for studying the genesis of Cottoidei is discussed.