Investigating the Role of SIFamide in the Effects of Food Deprivation on Female Reproductive Drive
Authors: Attilio Ceretti; Jill Schneider
Affiliation: Lehigh University
Keywords: g. courtship and mating; k. feeding behavior
Adaptation requires differential reproductive success, but reproductive processes are energetically expensive and can compromise the chances of survival under energetic challenges. Thus, many species appear to have evolved mechanisms that inhibit reproduction when energy is scarce. For example, in a genetically heterogenous population of Drosophila melanogaster derived from an orchard in New Jersey, we found that 36-48 hours of food deprivation in females significantly decreased the incidence of copulation with fed males, whereas food deprivation in males had no effect on courtship or copulation attempts with fed females. One signal that could be mediating these results is the evolutionarily conserved neuropeptide, SIFamide, the insect ortholog of the mammalian peptidergic/hormonal signal RFamide-related peptide-3, which mediates the effects of energy on reproduction in hamsters. To test whether this peptide mediates the effects of energy on reproduction, RNAi towards SIFamide was expressed in SIFamide neurons. Wildtype control females decrease their mating rate and increase their latency to copulate following only 24 hours of food deprivation, while females that express RNAi toward SIFamide do not. Knockdown of SIFamide blocks the effects of food deprivation on female reproduction, consistent with the idea that SIFamide expression is important for the inhibition of reproduction when energy is scarce. Our results provide a potential neurological basis for an ancestral system that mediates tradeoffs in food intake and reproduction.