The effects of reduced rpd3 levels on fly physiology.

BACKGROUND: Rpd3 is a conserved histone deacetylase that removes acetyl groups from lysine residues within histones and other proteins. Reduction or inhibition of Rpd3 extends longevity in yeast, worms, and flies. Previous studies in flies suggest an overlap with the mechanism of lifespan extension by dietary restriction. However, the mechanism of rpd3's effects on longevity remains unclear. OBJECTIVES: In this study we investigated how rpd3 reduction affects fly spontaneous physical activity, fecundity, and stress resistance. METHODS: We examined the effects of rpd3 reduction on fly spontaneous physical activity by using population monitors, we determined female fecundity by counting daily egg laying, and we determined fly survivorship in response to starvation and paraquat. RESULTS: In flies, rpd3 reduction increases peak spontaneous physical activity of rpd3 ^def male flies at a young age but does not affect total 24 hour activity. Male and female rpd3 ^def mutants are more resistant to starvation on low and high calorie diets. In addition, increased resistance to paraquat was observed in females of one allele. A decrease in rpd3 levels does not affect female fecundity. CONCLUSIONS: A decrease in rpd3 levels mirrors some but not all changes associated with calorie restriction, illustrated by an increased peak of spontaneous activity in rpd3 ^def /+ heterozygous male flies but no effect on total spontaneous activity and fecundity.