Age-related changes in the body composition of mated and unmated blowflies Phormia terrae novae

The quantitative relationship between life span, food ingestion, egg production, mating, and flight-activity of protein-fed blowfly Phormia terrae novae females

The age-dependent variations in the amount of food ingestion, egg production, and flight activity of protein-fed female Phormia terrae novae were analyzed. Also the influence of mating and forced physical performance on the time course of these parameters and on life span were tested. In virgin females, the life span with the investigated factors is generally delayed, together with mean and maximum life span. In comparison to mated females virgin females exhibit a 40% prolongation of mean life span and ingest more sugar with a later intake maximum. Their egg production starts 5 days later (Day 10) but reaches only half the amount occurring in mated females. Flight performance is generally higher in virgin females, reaching its maximum 2 days later (Day 14), with a more gradual decline instead of the sudden drop in flight performance seen in mated flies. Females receiving their food by flight only ("forced fliers") show a shorter mean life span (which is more pronounced in virgin flies). The maximum of sugar intake shifts forward to an earlier point after eclosion, and the amount is reduced by about 30% over the entire life span. Similarly, the egg production rate reaches lower values and tends to have an earlier maximum in comparison to corresponding groups that had access to sugar on the cage floor. The results further support the hypothesis that Phormia exhibits a strictly programmed aging pattern. Its time course depends on reproduction sufficiency and physical performance. Both factors act to shorten life expectation.

Influence of age and diet on DNA synthesis and the DNA content of mid-gut cells in the dipteran Sarcophaga carnaria

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.