Compensatory ingestion upon dietary restriction in Drosophila melanogaster

Abstract

Dietary restriction extends the lifespan of numerous, evolutionarily diverse species. In D. melanogaster, a prominent model for research on the interaction between nutrition and longevity, dietary restriction is typically based on medium dilution, with possible compensatory ingestion commonly being neglected. Possible problems with this approach are revealed by using a method for direct monitoring of D. melanogaster feeding behavior. This demonstrates that dietary restriction elicits robust compensatory changes in food consumption. As a result, the effect of medium dilution is overestimated and, in certain cases, even fully compensated for. Our results strongly indicate that feeding behavior and nutritional composition act concertedly to determine fly lifespan. Feeding behavior thus emerges as a central element in D. melanogaster aging.

Figure 1

Regulation of feeding behavior in response to dietary modulation. (a) Volume of food ingested per fly over 24 h on four different medium concentrations at 25 °C (mean ± s.d. of four replicate samples of 15 females each). Unpaired, two-tailed t tests: 1× versus 5×, P = 0.0001; 5× versus 10×, P = 0.0005; 10× versus 15×, P = 0.0003 (b) Net sucrose and yeast extract intake on the four nutritional conditions, in micrograms ingested per fly per 24 h (mean ± s.d.). Inset, actual nutrient intake (solid line) markedly differs from expected intake based on medium concentration only (dashed line).

Figure 2

Feeding behavior influences D. melanogaster lifespan. (a) Survival for virgin females at 25 °C on four different nutritional concentrations. Longevity correlates with actual food intake. (b) Mean lifespan as a function of medium concentration. Survival on 5× is 28% shorter than on 1× (logrank test, P < 0.0001, χ² = 134.8), and 17% longer than on 10× (logrank test, P < 0.0001, χ² = 30.72), whereas lifespan on 10× and 15× does not differ significantly (logrank test, P = 0.7993, χ² = 0.06466). 1×, n = 172, mean = 55 d; 5×, n = 187, mean = 40 d; 10×, n = 137, mean = 34 d; 15×, n = 178, mean = 35 d.