Changes in nucleic acid content in aging Drosophila bipectinata

Age-related RNA decline in adult Drosophila melanogaster

We investigated the correlation between age and total RNA levels in long-lived and control lines of Drosophila melanogaster. Total RNA was extracted at 10 ages from 1-63 days posteclosion from 3 inbred lines, with replication. Three different methods of RNA quantitation gave highly correlated estimates. Total RNA declined substantially with age, exhibiting a dramatic drop in the first few days of adult life. We find no evidence for a causal relationship between adult longevity and total RNA levels, since long-lived and control lines exhibited similar patterns of age-related RNA decline. These observations suggest that the dramatic decline in total RNA that occurs early in adult life does not explain the twofold differences in life span between lines. The pattern of age-specific decline coincides with published observations on age-specific metabolic rates, and suggests that 14-day-old flies are functionally senescent.

Changes in total and mitochondrial nucleic acid content in aging Caryedon serratus Oliver (Coleoptera)

Aging in the beetle Caryedon serratus was accompanied by a decline in total DNA content (9.28% in males and 9.79% in females). Mitochondrial DNA remained constant until the 11th day of age and then decreased gradually with advancing age in both sexes. RNA content and the RNA/DNA ratio showed similar changes in whole body as well as mitochondrial fractions. The two parameters decreased continuously and significantly (p less than 0.001) in males whereas in females an initial rise during the reproductive period was followed by decline until death. The observations suggest that there is a loss of mitochondria in the senescent period and a decline in the total nucleic acid content and protein synthetic capacity of C. serratus.

Age-associated changes in nucleic acid content in Zaprionus paravittiger

The mean life span of male and female Zaprionus paravittiger reared on corn meal agar medium at 26 +/- 2 degrees C was found to be 35 and 40 days, respectively. The DNA content showed a perpetual decline in both sexes. The RNA content also showed a continuous decline in males while in females a significant leap is found during the first 17 days followed by a steady decline until the 41st day. The study supports the concept that protein synthesis (RNA-DNA) and thus the biological expression during different phases of life, are controlled at the DNA-RNA level.