Erika Armstrong
Review Paper Assignment
BZ 311 Summer 2011

	It has been shown many times over that mating induces stereotyped behaviors in female Drosophila melanogaster and other insects (1,2). These wild-type mating responses include reduced receptivity, and an increase in egg laying and ovipositor extrusions (2). The factor that induces these behaviors is the Sex Peptide, or SP (1, 2, 3). In the paper by Yapici et al., the researchers investigate CG16752, which they determined was the Sex Peptide Receptor, henceforth referred to as SPR. Their evidence suggests that SP travels from the female reproductive tract to the CNS where it acts on the SPR. The authors postulate that, because SPR is highly conserved among insects, it may be possible to find “new approaches” to control pests and disease vectors (2).
	In order to test their hypothesis, Yapici et al. used females deficient for SPR. These individuals lay fewer eggs than the wild-type and expressed identical behavior post-mating as their virgin wild-type counterparts (2). This is in concurrence with the findings of Liu and Kubli who, rather than altering the SPR in females created males with mutant SP (1).
	In order to confirm that these behaviors were in fact due to a mutant SPR and not some other cause, Yapice et al. determined that sperm transferal, storage, and egg development proceeded typically with the use of GFP (2). Although there are several fluorescent proteins, GFP, or Green Fluorescent Protein, refers specifically to the bioluminescent protein isolated from the jellyfish Aequorea victoria. Physically, it is "an 11-stranded β-barrel threaded by an α-helix running up the axis of the cylinder" and obviously has applications as both a tag and indicator. Because of the amount of research gone into GFP, it is relatively straightforward to introduce as a transgene (4). In this case, GFP had been attached to Drosophila sperm (2).
	Additionally, the researchers used two methods to control for the potential offset of the first RNAi. For the first method, they generated a line independent from the first that targeted SPR in a different location. This was accomplished by cloning a PCR product into an inverted repeat, and inserting that into the second location via a vector (2). Yapici et al. used the φC31 system to insert the transgenes. ΦC31 is known for its efficiency, lack of requirement for cofactors, being site-specific, and its implementation across several genera including Drosophila (5).
	For the second method, the authors completely removed the SPR along with four other genes via the use of a molecularly defined deficiency (2).  This method, described by Parks et al. is “moderately efficient” and “enables the generation of small custom deletions with predictable endpoints” (6).  In order to create deletions with molecularly defined endpoints, Parks et al. carried out a series of crosses. Males were chosen by selecting transposon elements that flanked the sequence they wanted to delete, while females had a FLP recombinase transgene. After the second cross, progeny and parents were exposed to heat shock treatement. Several more crosses were created before the resulting progeny were collected as stock (6).
	Due to the reliability of these aforementioned methods, Yapici et al. could be reasonably certain that they successfully targeted the SPR. A second hurdle besides correctly targeting the SPR was to confirm the prediction that SPR is a G-protein coupled receptor. In order to do this, the authors