Preferential association of nucleolar organizing human chromosomes as revealed by silver staining technique at mitosis

Abstract

The frequency of different types of satellite associations of nucleolar organizing human chromosomes (i.e. acrocentric chromosomes; 13, 14, 15, 21, and 22) is reported using 10 normal individuals by Ag-staining technique. The preferential involvement of acrocentric chromosomes in satellite association is suggested. Only acrocentric chromosomes with active NORs (i.e. Ag-stained) were found in association while unstained (inactive NORs) chromosomes were never seen in satellite association. In general as number of NORs expression increase, the frequency of association per cell was also increased. A possible mechanism and the clinical consequences of such an unusual phenophenon is described.

A first generation cytogenetic ideogram for the Florida manatee (Trichechus manatus latirostris) based on multiple chromosome banding techniques

“…It has been demonstrated that only chromosomes with active NORs are involved in satellite associations, observable in cytogenetic preparations (V erma et al . 1983).…”

“…It has been demonstrated that only chromosomes with active NORs are involved in satellite associations, observable in cytogenetic preparations (VERMA et al 1983). Therefore, failure to observe satellite associations, other than those between chromosome 20 homologs, and/or additional Ag-NOR positive stained regions cannot exclude possible NOR sites elsewhere within the Florida manatee karyotype.…”

Detection of nucleolar organizer regions on chromosomes by flourescence in situ hybridization with human 28S rRNA gene and cloning of 28S rRNA gene in Sika deer

“…It has been speculated that NOR association increases probabilities of non‐disjunction and translocation during cell division (Ray & Pearson 1979). For example, high frequencies of NOR association in number 21 chromosomes made the risk of trisomy 21 or Down syndrome higher in humans (Verma et al . 1983).…”

An interstitial nucleolus organizer region in the long arm of human chromosome 7: cytogenetic characterization and familial segregation

“…Numerous studies have been performed to identify the chromosomes involved in such associations (e.g. Patil and Lubs, 1971;Jacobs et al, 1976;Verma et al, 1983). NOR associations have also been observed with interstitially located NORs (Henderson et al, 1974;Warburton et al, 1973Warburton et al, , 1975Prieto et al, 1989).…”