title: Influence of age and diet on DNA synthesis and the DNA content of mid-gut cells in the dipteran Sarcophaga carnaria.
abstract: Virgin female Sarcophaga carnaria maintained on a diet of sugar and water had shorter lifespans than those maintained on a liver, sugar and water diet; there was no significant different between the lifespans of mated females or mated males kept on the two diets. Autoradiographs of mid-gut sections from virgin females which had been fed with [3H]thymidine showed substantial amounts of DNA synthesis in the nuclei during at least the first 14-15 days of adult life. Cytophotometric measurements of Feulgen-stained mid-gut nuclei of 0--1-, 2--3-, and 14--15-day-old females showed that the integrated absorbances peaked at values corresponding approximately to 2 C, 4 C, 8 C, 16 C and 32 C. The proportion of nuclei with the higher Feulgen-DNA values increased with age, and was greater in flies maintained on the liver, sugar and water diet. It is suggested that the DNA synthesis observed is associated with polytenization rather than mitotic cell division, and that the level of polyteny reached may reflect age- and diet-related differences in the functional demand made on mid-gut cells.
mesh_terms: D000375:Aging; D000818:Animals; D004261:DNA Replication; D004032:Diet; D004175:Diptera / Q000502:physiology*; D005260:Female; D007422:Intestines / Q000166:cytology / Q000502:physiology; D008136:Longevity