Compensatory changes in silver-stainability of nucleolar organizer regions in mice.
Silver-stainability of nucleolar organizer regions (NORs) that contain genes for ribosomal RNA (rDNA) was investigated using two mouse strains, BALB/cCrSlc and MOA, and their hybrid progeny. The patterns of segregation of the rDNA clusters were analyzed in terms of chromosomal C-banding and by use of a polymorphic probe for the variable region in backcrossed N2 and N3 individuals. The results indicate that the intensity of Ag-NOR staining is stably inherited in most of the rDNA clusters, irrespective of different genetic backgrounds. In some clusters, such as those on chromosome 12 of BALB/cCrSlc, a modulation of the intensity is observed. This modulation seems to be due to compensatory activation via a change in the number of actively transcribed genes. The change from silver-negative to silver-positive staining of the NOR of chromosome 12 of BALB/cCrSlc was correlated with demethylation of the genes.
Suzuki
H
H
Division of Molecular Genetics, Jikei University School of Medicine, Tokyo, Japan.
Sakurai
S
S
Nishimura
M
M
Kominami
R
R
Moriwaki
K
K
D000818:Animals; D002875:Chromosomes; D004275:DNA, Ribosomal / Q000235:genetics*; D007621:Karyotyping; D008745:Methylation; D051379:Mice; D009697:Nucleolus Organizer Region; D012335:RNA, Ribosomal / Q000235:genetics*; D016622:Silver Staining
D004275:DNA, Ribosomal; D012335:RNA, Ribosomal