[Organization of Bsp-repeats in the fox genome]

Bsp repeats comprise approximately 1% of silver for total DNA and are preferentially localized in centromeric regions. Two of Bsp fragments cloned earlier, such as non-homologous rsV1 and rsV3, make up together a Bsp unit (680 bp) and possess a set of sites known to have regulatory functions in eucaryotic genomes. In this work, tandem organization of Bsp repeats is demonstrated. A stretched Bsp sequence (approximately 1460 bp, dimeric form) flanked by BamHI sites was cloned and its restriction map was plotted. With use of rsV1 and rsV3 probes the new sequence exhibited linked structure: rsV1-rsV3-rsV1-rsV3-rsV1. Blot-hybridization with the restriction fragments of fox total DNA suggested hierarchical order of Bsp clustes in the genome. It is supposed that the processes of selective amplification of individual fragments had been of real importance during evolution of Bsp repeats.