Constitutive heterochromatin polymorphism in river buffalo chromosomes

Constitutive heterochromatin (HC) distribution among river buffalo (Bubalus bubalis L., 2n=50) chromosomes was analyzed by using both the CBA-technique and GBA + CBA technique. CBA-banding revealed the presence of HC in the centromeric regions of all the chromosomes of the 15 animals we investigated. The five biarmed pairs showed very small HC-blocks, the remaining autosomes and the X-chromosomes showed pronounced HC-blocks with a high degree of HC-variation among them. The Y-chromosome showed a variable C-banding pattern on the basis of the different degree of chromosomal denaturation. A C-positive and heteromorphic band was also found at the telomere of chromosome 4p. The simultaneous visualization of fluorescent C and G-bands (GBA + CBA technique) in 10 animals allowed us to study the HC-distribution among and within chromosome pairs. Chromosomes showing HC-polymorphism between chromosome pairs were number 6 (6/10 animals), 11 (5/10 animals), 19 (5/10 animals) and 24 (7/10 animals).