Chromatin condensation in the aging housefly

Computer analysis of digitized images of Feulgen-stained optic lobe and Malpighian tubule nuclei from the adult male housefly has shown significant age-related changes in several image features. These features relate to the amount and spatial distribution of a high and medium density chromatin component (HDC, MDC). Total DNA content in both the brain and tubule nuclei did not change with age. The amount of HDC nearly doubles by day 3 (post-eclosion) in the brain, while the amount in the tubules increases nearly four-fold by day 8. This condensation event is accompanied by a seven-to-eight-fold increase in the symmetry of the HDC distribution pattern. The number of MDC clusters in the tubule shows a five-fold decrease, while the number of MDC clusters in the brain remains unchanged. The condensation pattern in the brain nuclei changed more rapidly than it did in the tubule nuclei. The changes in the brain nuclei were found to occur between day 1 and day 4, while the tubule nuclei showed significant changes between day 1 and day 8. The significance of this difference is discussed with respect to Hypothalamic theories on the aging process in animals.