Figure 4.

ppk25-Gal4 is expressed in two subsets of olfactory neurons that stimulate male courtship. A, Immunostaining reveals mCD8-GFP expression in olfactory neurons within the third antennal segment of ppk25-Gal4;UAS-mCD8-GFP males. B, Whole-brain immunostaining of males of the same genotype with neuronal-specific nc82 decorates the glomeruli of the antennal lobe. C, Staining with anti-GFP reveals the axonal projections of ppk25-Gal4-expressing neurons. D, A superimposition of the two immunostaining patterns shows that the antennal neurons that express ppk25-Gal4 project to two glomeruli that are easily identified by their position on the antennal lobe and characteristic shapes: Va1v, also called Va1lm, and VL2a (Couto et al., 2005; Fishilevich and Vosshall, 2005). Both Va1v and VL2a are sexually dimorphic and express fru (Kondoh et al., 2003; Stockinger et al., 2005). VA1v receives projections from olfactory neurons that respond to female cuticular extracts and express Or47b, an olfactory receptor for fly odors (van der Goes van Naters and Carlson, 2007; Root et al., 2008; Wang et al., 2011), while VL2a is innervated by olfactory neurons that express IR84a and stimulate courtship in response to aromatic food odors (Grosjean et al., 2011).