The chromosomal distribution and organization of sheep satellite I and II centromeric DNA using characterized sheep-hamster somatic cell hybrids.

A panel of sheep-hamster somatic cell hybrids containing single sheep chromosomes was used to study the chromosomal distribution and organization of two families of sheep centromeric satellite DNA. This study shows that the centromeres of the sheep metacentric chromosomes 1, 2 and 3 differ in their organization and relative quantities of sheep satellite I DNA. The results, when correlated with the proposed formation of these metacentric chromosomes by ancient Robertsonian translocations, suggest a loss or replacement of satellite I centromeric DNA from the centromeres of these sheep chromosomes. Using Southern blot analysis and fluorescence in situ hybridization, this study shows that the recent centric fusion chromosome t2 (rob 9;10) contains little satellite II DNA. Together these results suggest the possibility of substantial reorganization of sheep centromeric DNA families after Robertsonian translocations.