Differential Chromosomal Staining in Bos taurus (Cattle)

The centromeric regions of the cattle chromosomes exhibit a variable staining property, if staining procedures, which visualize the constitutive heterochromatin in some other species, are used. These regions are non-fluorescing with the fluorochrome “Hoechst 33258” (a benzimidazol derivative) and remain unstained following the staining methods for C and G-banding. However, using the heat denaturationrenaturation procedures, the centromeric regions are darkly stained. This differential behaviour of the centromeric heterochromatin in Bos taurus suggests that the constitutive heterochromatin is heterogeneous in its staining intensities and thus, its variable staining properties may be due to its complex structure or its compositional heterogeneity.