SEX-CHROMOSOMES, MICRONUCLEI AND AGING IN WOMEN

Several studies on aneuploidy and aging have shown a significant incre ase in the loss of chromosomes in both males and females with age. Oth ers have observed a significant increase in micronucleus formation in lymphocytes with age. The objectives of this investigation were to det ermine the relationship between sex chromosome loss and increased micr onucleus frequencies with age, to establish sex chromosome loss freque ncies unbiased by cellular survival factors or slide preparation, and to determine the effect of smoking on sex chromosome loss. Blood sampl es were obtained from 8 newborn females and 38 adult females ranging i n age from 19 to 77. Isolated lymphocytes were cultured according to s tandard techniques and blocked with cytochalasin B. Two thousand binuc leated cells per donor were scored using a modified micronucleus assay to determine the kinetochore status of each micronucleus. Slides were then hybridized with a 2.0 kb centromeric X chromosome-specific probe labeled with biotinylated dUTP, and detected with fluorescein-conjuga ted avidin. All micronucleated cells were relocated and their X chromo some status was determined. We found the X chromosome to be present in 72.2% of the micronuclei scored; additionally our results show a sign ificant increase with age in the number of micronuclei containing an X chromosome.