Nucleolus organizer regions in two species of Bovidae

Silver-staining of nucleolar organizer regions (NORs) in somatic cells of Holstein cattle (Bos taurus) and European buffalo Murrah type (Bubalus bubalus) indicates that the NORs are located in the telomeres of chromosomes 2,3,4,11, and 29 of cattle and chromosomes 3,4,6,23, and 24 of buffalo. Chromosome identification was by Q-banding. Analysis of 326 metaphase cells showed a mean value of 7.7 +/- 1.2 for Ag-NORs with a range between 4 and 10 for cattle. In all of the cells examined, either one or both homologues of chromosome 29 showed telomeric silver staining for cattle. Meiotic preparations showed not more than 5 clusters of silver grains in the pachytene stage of cattle.