Changing Her Ways

Abstract

Sex peptide (SP, a component of seminal fluid) elicits marked changes in the behavior of female Drosophila melanogaster : They lay eggs and are no longer receptive to male courtship. Yapici et al . used a genome-wide transgenic RNA interference (RNAi) screen to identify a gene ( SPR , for sex peptide receptor) whose disruption led to a decrease in egg laying. Whereas virgin SPR RNAi females behaved like control females, mated females, in addition to laying few eggs, failed to reject courtship by a second male. Similarly, SPR RNAi females remained receptive to courtship after exposure to SP. When SPR (predicted to encode a G protein-coupled receptor) was expressed in Chinese hamster ovary (CHO) cells, it responded to nanomolar concentrations of SP and the related peptide DUP99B (which also elicits the postmating response) but not to other Drosophila peptides. Experiments involving coexpression of chimeric heterotrimeric GTP-binding protein α subunits suggested that SPR coupled to Gα i , Gα o , or both, to regulate adenosine 3',5'-monophosphate (cAMP) concentrations. SPR was present in the brain and ventral nerve cord, as well as in the female reproductive tract, and, in a subset of neurons, was coexpressed with fruitless , a gene previously implicated in determination of courtship behavior. SPR knockdown in fruitless neurons mimicked SPR deficiency, whereas selective expression of SPR in fruitless neurons rescued the remating phenotype and partially rescued egg laying. Putative SPR orthologs were identified in other insect genomes, and those from Drosophila pseudoobscura , Aedes aegypti , and Bombyx mori responded to SP and DUP99B in the CHO cell assay. The authors predict that the identification of SPR may lead to new strategies for controlling insect pests, and, in commentary discussing this research in the context of male reproductive strategies, Griffith notes the similarity between Drosophila and vertebrate seminal fluid. N. Yapici, Y.-J. Kim, C. Ribeiro, B. J. Dickson, A receptor that mediates the post-mating switch in Drosophila reproductive behaviour. Nature 451 , 33-37 (2008). [PubMed] L. C. Griffith, Love hangover. Nature 451 , 24-25 (2008). [PubMed]