Figure 1.

Enhanced aggression is seen in male flies with feminized cholinergic neurons. (A) Significant increases are seen in the numbers of lunges in male flies with feminized cholinergic neurons (cha-Gal4/UAS-tra, n = 35) when compared to the two parental lines (cha-Gal4/+, n = 34 and UAS-tra/+, n = 35) (B) The enhanced aggression seen in male flies with feminized cholinergic neurons is dependent on the developmental stage. Flies carrying the temperature sensitive Gal80 (w; cha-GAL4/UAS-tra;tub-Gal80^ts/+) were raised at 19°C (permissive) or 30°C (restrictive). Enhanced aggression was seen in flies reared continuously at the restrictive temperature (n = 34). Temperature shifts were performed at the late third instar stage to search for a critical period for feminization. Flies that were feminized during the embryonic and larval stages (restrictive to permissive) showed no enhanced aggression (n = 34). When cholinergic neurons were feminized during the late larval/early pupal stages, however, significant increases were seen in the numbers of lunges (n = 35). (C) Males with feminized cholinergic neurons showed the typical male aggressive behavioral patterns, lunging and boxing rather than the female patterns, shove and head butt (n = 20). (D) Males showed higher levels of male-male courtship behavior than the parental controls. (E–G) Male flies with feminized cholinergic neurons (experimental flies) showed high levels of aggression earlier than control parent lines in standard fighting arenas. Both the numbers of lunges per fight (E) and the lunges per encounter (F) were significantly higher in the experimental line (cha-Gal4/UAS-Tra) compared to both parental lines. The latency to the first lunge (G) also was shorter in the experimental flies (n = 20). (*p < 0.05; **p < 0.01; ***p < 0.001, analyzed by Kruskus-Wallis ANOVA and Dunn's Multiple Comparison Test).