prt1 mutants were surprisingly fecund given their contorted mating positions. They were able to produce approximately half the number of offspring as CS flies ( Figures 6E). Either insemination occurred during periods when the male was correctly oriented, or wild-type position is not required for insemination. The total duration of copulation was also decreased in prt1 ( Figure 7B). It is perhaps surprising that the decrease in copulation AZD5363 chemical structure time and fecundity were not more severe given the tremendous struggling

observed in mating pairs. To confirm that the copulation defects we observed were due to prt1 rather than another spurious mutation, we performed genetic rescue experiments with UAS-prt transgenes. The circuitry involved in copulation is not known. Therefore, to maximize our chances of expressing prt1 in the relevant tissue, we used the broadly distributed driver daughterless-Gal4 (Da-Gal4). As controls, we tested the Da-Gal4 driver alone and the UAS-prt transgenes alone, and none rescued the copulation deficit ( Figure 7A). In contrast, when Da-Gal4 was used in combination with a UAS-prt transgene on the third chromosome, we saw rescue of the copulation phenotype ( Figure 7A). We replicated these results using a UAS-prt transgene on the

second chromosome ( Figure 7A). Similarly, we found that the decrease in copulation duration was rescued using Da-Gal4 and either of these UAS-prt transgenes, selleckchem but

not by Da-Gal4 or UAS-prt alone ( Figure 7B). Taken together, these data confirm that prt plays a critical role in an important but poorly described aspect of D. melanogaster sexual behavior. Although the MBs have been previously 3-mercaptopyruvate sulfurtransferase linked to courtship behavior (O’Dell et al., 1995 and Sakai and Kitamoto, 2006), we wanted to explore whether the MBs could also be involved in copulatory behavior. To this end, we performed genetic rescue experiments using OK107-Gal4, a driver commonly used for expression in the MBs (e.g., Connolly et al., 1996). OK107-Gal4 combined with a UAS-prt transgene on either the second or third chromosome resulted in rescue of the copulation phenotype, whereas the controls did not ( Figure 7C). We found that the decrease in copulation duration was also rescued using OK107-Gal4 and either of these UAS-prt transgenes ( Figure 7D); the second chromosome UAS-prt transgene alone also appeared to rescue copulation duration, presumably due to leaky expression of PRT. Although we cannot rule out the possibility that other cells expressing OK107-Gal4 are responsible for these effects, these data suggest that the MBs play a critical role in copulatory behavior. At present, we do not know the PRT substrate, and we suggest that it may be an unknown neurotransmitter.