Location of human satellite DNAs on the Y chromosome

Abstract

THE technique of in situ hybridisation of radioactively labelled DNA or RNA to the denatured DNA in metaphase chromosomes provides a powerful and popular method for identifying the chromosomal location of specific repeated DNA sequences^1,2. In man, this technique has been used to map the ribosomal cistrons (ref. 3 and H.J.E., M. L. Pardue, and R.A.B., in preparation) and to examine the chromosomal location of three of the four known satellite DNAs^4–8. Satellite II (ref. 6) was found in the centromeric hetero-chromatic regions (C band) of chromosome 1 and in the C bands of one C group (chromosome 9) and one E group chromosome pair (tentatively identified as chromosome 16). Satellite III (ref. 8) was found mainly in the C band of chromosome 9, with some in the centromere/short arm regions of the D and G group chromosomes, and possibly in the C bands of chromosomes 1 and 16. The satellite DNA investigated by Saunders et al.⁷ (which is probably identical to satellite IV of Corneo et al.⁵) was only positively identified in the C band of chromosome 9, although other regions of hybridisation were noted. In all these studies on satellite DNAs, the auto-radiographic observations were limited because no general chromosome identification was possible. Thus, only major sites of hybridisation could be detected and in some instances the locations of these sites were in doubt.