Introduction

In many insects mating triggers a remarkable change in the behaviour of the female: they are no longer attractive to males, they are not responsive to mating and they increase feeding and egg production (see Chen et al., 1988; Chapman et al., 2003; Kubli, 2003). In Drosophila a main trigger of this post-mating behaviour is sex peptide (SP) that is transferred to the female in the seminal fluid (Chen et al., 1988; Liu and Kubli, 2003). The SP, also known as Acp70A, is encoded on the precursor gene CG8982 and is produced in the male accessory glands. It is, thus, a male specific peptide, and is not found outside the genus Drosophila. SP consists of 36 amino acids with the sequence WEWPWNRKPTKFPIPSPNPRDKWCRLNLGPAWGGRC (Chen et al., 1988). SP acts on a GPCR (SPR; CG16752) shared with myoinhibitory peptides (MIP1-5; also known as allatostatin B1-5) in Drosophila (Kim et al., 2010; Poels et al., 2010). This MIP receptor exists in most studied insects (see entry for myoinhibitory peptides), although the bona fide SP is only found in Drosophila (Kim et al., 2010; Poels et al., 2010; Tsuda and Aigaki, 2016).

Location

SP is produced in the male accessory glands. The SP/MIP receptor is widely distributed in the CNS, but a small set of sensory neurons in the reproductive tract, with axions entering the CNS, is critical in mediating the response to SP (Yapici et al., 2008; Hänsemeyer et al., 2009; Yang et al., 2009).

Function

SP is transferred with the semen, bound to the sperms, and acts on the SP receptor in sensory neurons of the female reproductive tract to trigger a long-lasting response, which alters behaviour and physiology of the fly (Chen et al., 1988; Aigaki et al., 1991; Kubli, 2003; Chapman et al., 2003). The SP mediated switch in behaviour/physiology depends on a network of about 2000 neurons in the CNS that express then transcription factor fruitless (fru; Yapici et al., 2008; Yang et al., 2009; Rezaval et al., 2012). The mated females are no longer receptive to courting males, they increase food intake and lay many eggs. SP also changes sleep behaviour of mated flies (Isaac et al., 2009). Mated females sleep less than male flies, probably to increase foraging to ensure nutrients for egg development and to search for sites for egg-laying. In contrast, virgin females display a male-like sleep pattern with a midday siesta. Thus, SP transferred at mating induces an 8-day-long reduction (by 70%) of this daytime rest (Isaac et al., 2009). Finally, it is known that females develop a strong appetite for sodium after mating. This appetite for salt is caused by a SP-mediated modulation of taste processing (Walker et al., 2015).

Suggested Reviews

• Dickson BJ. 2008. Wired for sex: the neurobiology of Drosophila mating decisions. Science 322(5903):904-909.
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• Kubli E. 2003. Sex-peptides: seminal peptides of the Drosophila male. Cellular and molecular life sciences 60(8):1689-1704.
  View Review
• Tsuda M, Aigaki T. 2016. Evolution of sex-peptide in Drosophila. Fly 10(4):172-177.
  View Review

References

• Aigaki T, Fleischmann I, Chen PS, Kubli E. 1991. Ectopic expression of sex peptide alters reproductive behavior of female D. melanogaster. Neuron 7(4):557-563.
• Chapman T, Bangham J, Vinti G, Seifried B, Lung O, Wolfner MF, Smith HK, Partridge L. 2003. The sex peptide of Drosophila melanogaster: female post-mating responses analyzed by using RNA interference. Proc Natl Acad Sci U S A 100(17):9923-9928.
• Chen PS, Stumm-Zollinger E, Aigaki T, Balmer J, Bienz M, Bohlen P. 1988. A male accessory gland peptide that regulates reproductive behaviour of female D. melanogaster. Cell 54(3):291-298.
• Häsemeyer, M., Yapici, N., Heberlein, U., and Dickson, B.J. (2009). Sensory neurons in the Drosophila genital tract regulate female reproductive behaviour. Neuron 61, 511-518.
• Kim YJ, Bartalska K, Audsley N, Yamanaka N, Yapici N, Lee JY, Kim YC, Markovic M, Isaac E, Tanaka Y, Dickson BJ. 2010. MIPs are ancestral ligands for the sex peptide receptor. Proc Natl Acad Sci U S A 107(14):6520-6525.
• Kubli E. 2003. Sex-peptides: seminal peptides of the Drosophila male. Cellular and molecular life sciences 60(8):1689-1704.
• Poels J, Van Loy T, Vandersmissen HP, Van Hiel B, Van Soest S, Nachman RJ, Vanden Broeck J. 2010. Myoinhibiting peptides are the ancestral ligands of the promiscuous Drosophila sex peptide receptor. Cellular and molecular life sciences 67(20):3511-3522.
• Rezaval, C., Pavlou, H.J., Dornan, A.J., Chan, Y.B., Kravitz, E.A., and Goodwin, S.F. (2012). Neural circuitry underlying Drosophila female postmating behavioral responses. Current biology : CB 22, 1155-1165.
• Walker, S.J., Corrales-Carvajal, V.M., and Ribeiro, C. (2015). Postmating Circuitry Modulates Salt Taste Processing to Increase Reproductive Output in Drosophila. Current biology : CB 25, 2621-2630.
• Yang, C.H., Rumpf, S., Xiang, Y., Gordon, M.D., Song, W., Jan, L.Y., and Jan, Y.N. (2009). Control of the postmating behavioral switch in Drosophila females by internal sensory neurons. Neuron 61, 519-526.
• Yapici, N., Kim, Y.J., Ribeiro, C., and Dickson, B.J. (2008). A receptor that mediates the post-mating switch in Drosophila reproductive behaviour. Nature 451, 33-37.