Meeting Abstract
Over 90 generations of selection for starvation resistance in outbred populations of Drosophila melanogaster have resulted in flies that are extremely obese, even when fed a standard Drosophila diet. Obesity can also be induced in normally lean flies by rearing them on a low-protein, high-sugar diet. We investigated whether starvation-selected flies respond differently to dietary changes than controls. Have starvation-selected populations reached their maximum lipid content, or can they be made even more obese through dietary manipulations? We reared starvation-selected and unselected lean control larvae on diets containing 5 yeast:sucrose ratios, ranging from 90% yeast:10% sugar (Atkins diet) to 10% yeast:90% sugar (American diet), as well as 3 different caloric concentrations. Starvation-selected and control flies had similar responses to rearing diet: development to adulthood was delayed on high sugar diets, and flies reared on high sugar diets eclosed with significantly greater lipid stores. Total protein levels were not affected, indicating that these flies were fatter, not simply larger due to extended larval feeding. To determine whether lack of micronutrients contained in yeast could have affected these results, we reared flies on high-sugar media containing vitamins, trace metals, cholesterol or RNA, as well as a combination of all of these. Lipid content did not differ from that of flies reared on un-supplemented media. We conclude that starvation-selected flies have not become as obese as possible, despite long-term directional selection favoring lipid storage. Supported by IOS-1355210 and DBI REU 1358896 from NSF and R15-GM100395 from NIGMS.
