Giemsa banding,quinacrine fluorescence and DNA-replication in chromosomes of cattle (Bos taurus)

Almost all the 30 chromosome pairs of cattle can be identified by their banding patterns made be visible by a Giemsa staining technique described previously. The banding pattern of the X chromosome shows striking similarities with the banding pattern of the human X chromosome. — The centromeric region of the acrocentric autosomes contains a highly condensed DNA. This DNA is removed by the Giemsa staining procedure as can be shown by interference microscopic studies. If the chromosomes are stained with quinacrine dihydrochloride these centromeric regions are only slightly fluorescent. — Autoradiographic studies with ³H-thymidine show that the DNA at the centromeric regions starts and finishes its replication later than in the other parts of the chromosomes.