DNA methylation, ageing and ribosomal genes activity.

DNA methylation is an epigenetic mechanism controlling of gene expression. We studied the effect of a demethylation agent 5-azacytidine, on ribosomal gene activity observed by Nucleolus Staining Giemsa in the chromosomes of eight Alzheimer's disease patients, eight elderly healthy individuals and eight young healthy controls. Metaphase cells were obtained from lymphocyte cultures. All the acrocentric chromosome pairs were analyzed using G banding followed by Nucleolus Staining Giemsa banding in the same cell. The Alzheimer's disease patients and elderly healthy control did not show a variation in the transcriptional activity of ribosomal genes with or without 5-azacytidine treatment, whereas the young control group showed an increase in this activity with the treatment.