Figure 2. E49 neurons are necessary and sufficient for proboscis extension subprogram.
(A) Diagram of fly head with proboscis extended. The three segments of the proboscis are labeled, with arrows indicating their direction of movement during PER. The rostrum is extended and lifted upwards; the haustellum is extended by flipping downwards, away from its resting position against the rostrum; and the two lobes of the labellum are spread to allow food intake.
(B) Quantification (mean +/− s.e.m.) of PER phenotypes upon silencing of E49-Gal4 neurons. “Full extension” indicates movement of the rostrum, haustellum and labella. Flies expressing tetanus toxin driven by E49-Gal4 exhibit a specific deficit during extension. Frequencies are not significantly different (ns) between the three genotypes at either concentration. Values reflect 3 trials with 20–25 flies per trial per genotype.
(C) Time lapse photographs of wild-type (top row) and E49-Gal4, UAS-TNT (bottom row) flies following 100mM sucrose stimulation. Wild-type flies show full proboscis extension. E49-Gal4, UAS-TNT flies spread labella (arrows) and tilt head forward in the absence of other PER subprograms. Weak extension of the haustellum is observed after 5 seconds of stimulation. For movies, see supplemental materials (movies S1 and S2)
(D) Flies expressing ChR2 in Gr5a-expressing cells show robust full extension (black bars) in response to blue light (480 nm). Flies expressing ChR2 in E49-Gal4 neurons exhibit rostrum extension (gray bars) in response to blue light. n=45 flies for each genotype. Student t-test,*** = p<10−7.
(E) Time lapse photographs showing response of flies expressing ChR2 in Gr5a cells (top row) or E49-Gal4 neurons (bottom row) to intermittent exposure to red light (690 nm; 0s and 3s frames) and blue light (480 nm; 1s and 5s frames). For movies, see supplemental materials (movies S3 and S4).