AG-NOR STUDIES IN A HUMAN LYMPHOCYTE CULTURE - ARE VARIANTS LOCALIZEDTO SPECIFIC CHROMOSOMES

The genomic activity and polymorphisms of nucleolus organizer regions (NORs) were studied in an individual with routinely used AgNO3 and Q-b anding techniques. The results demonstrate that (a) the mean number of NORs per metaphase spread was 7.4, (b) chromosomes 14, 13, 15, and 21 showed variations of Ag-NOR in decreasing order, (c) chromosome 22 di d not show a polymorphism in any cell examined, and (d) both chromosom es 14 showed silver staining in most cells, Unlike many earlier report s indicating that NOR variants were constitutional in each individual, our present case represented a mosaic pattern of polymorphism involvi ng most of the D- and G-group chromosomes. (C) 1995 Wiley-Liss, Inc.