AGE-ASSOCIATED MICRONUCLEI CONTAINING CENTROMERES AND THE X-CHROMOSOME IN LYMPHOCYTES OF WOMEN

Chronological aging of women is clearly associated with an increase in both X-chromosome loss and micronuclei formation in peripheral lympho cytes. It has been suggested that micronucleus formation is an importa nt mechanism of chromosome loss. In the present study, fluorescence in situ hybridization was used to study micronuclei content in two age g roups (women below 30 and above 50 years old). A probe for centromeric alphoid consensus sequences (SO-alpha AllCen) and a cloned X-specific centromeric probe (pXBR) were separately used to detect the presence of any chromosomes and the X chromosome, respectively. The presence of centromere-positive micronuclei was significantly higher among the ol der donors (51.5%) than among the younger donors (34.3%). The X chromo some was highly overrepresented in the micronuclei, the older women sh owing a higher proportion of X-positive micronuclei (24.0 %) than the younger women (14.0 %). Assuming that the rest of the centromere-posit ive micronuclei contained autosomes, a significant age-dependent diffe rence was also noted for micronuclei harboring autosomes (27.5 % among the older women and 20.3 % among the younger women). These findings s uggest that both the X chromosome and autosomes are responsible for th e age-dependent increase of micronuclei in women's peripheral lymphocy tes.