Figure 3: The projection of SE0PG neurons is affected by nutrient conditions.
(a) The pupariation timing depends on the yeast concentration in food. The photo was taken at 144 h after hatching (hAH). While almost all animals pupariate on food containing 1.0–5.0 × yeast (2.0–10.0 g of yeast per 50 ml), larvae still remain in food containing 0–0.5 × yeast. Fifty larvae were placed in a 20 ml vial. (b) The normalized pupariation timing. In this and the subsequent figures, the percentages were normalized to the final number of pupae. Error bars represent s.e.m. Under the regular food condition, larvae pupariate at 96–120 hAH at 25 °C (n=274, 1.0 × yeast, black line). In contrast, 50% of larvae became pupae at 86.37±2.37 hAH under the rich food condition (n=324, 2.5 × yeast, red line) and at 195.8±17.5 hAH under the poor food condition (n=214, 0.2 × yeast, blue line). (c–f) The projections of SE0PG neurons (green) and PTTH neurons (red) were visualized with anti-serotonin and anti–HA antibodies in larvae expressing genomic ptth–HA. The PG was labelled with Sro (blue). The projecting neurites are indicated by arrows in the early third instar stage (0–6 h after L2–L3 moulting, A3L, c,d) and the prepupal stage (e,f). (g,h) The total length of SE0PG and PTTH neurons innervating the PG was measured in the early third instar and the prepupal stage. (i–n) SE0PG neurons respond promptly to food signals. When larvae were transferred from yeast-poor to yeast-rich food in the third instar stage, the SE0PG projections recovered after 2 days (i,j). The total length of the SE0PG projections was increased (m). Conversely, when larvae were transferred from regular food to yeast-free food in the early third instar stage, the SE0PG projections were severely disrupted (k,l). Note that the PG became smaller in l. The total length of projecting neurites was decreased (n). For statistical analysis in g,h,m,n, the mean values of 15–32 samples are shown with s.e.m. in each condition. Student’s t-test, *P<0.01. Bar, 50 μm. Each experiment was conducted independently at least four times.
