CHARACTERIZATION OF THE HETEROCHROMATIC CHROMOSOME REGIONS IN SHEEP

In order to elucidate the structural chromosome organization of the he terochromatic regions in sheep, we have used C-banding, silver-stainin g, sequential CDD technique and restriction endonuclease banding. By t hese banding techniques we obtained four fractions of repetitive DNA, the autosomal fractions A and B, the C fraction in the X chromosome, a nd the D fraction in the Y chromosome. Silver staining revealed active nucleolus organizer regions (NOR's) on the telomeric GC-rich areas of chromosomes 1, 2, 3, 4, and 25 which were digested with HaeIII restri ction endonuclease.