Exposure of elav /THA;THK late-stage embryos to exogenous DA rescues both the feeding and axonal fiber defects. A. Feeding. elav/THA;THK 16 hr old embryos were dechorionated, devitinellated, and placed in serum-free media until hatching (control), or in serum-free media plus 10-6 M DA-HCl (+DA), and compared with w1118/THA;THK 16 hour old embryos placed in serum-free media until hatching. n = 40 for behavioral analyses, from 4-6 independent experiments. B-E. Analysis of the 5-HT axonal fibers projecting to the foregut. B. Number of branches per 0.1 mm length along the axonal fiber. C. Number of total varicosities per 0.1 mm length; D. Number of varicosities > 5 μm2 per 0.1 mm length; E. Varicosity area. w1118/THA;THK, 38 fibers from 30 guts from 8 independent experiments; elav/THA;THK -DA, 40 fibers from 26 guts from 9 independent experiments; elav/THA;THK + DA, 43 fibers from 29 guts from 10 independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001. Statistical analyses were performed using one way ANOVAS and Dunnet's post-tests. Lines above the graph depict standard error of the mean. F - H. Visual depiction of 5-HT axonal fibers from elav/THA;THK (F), elav/THA;THK + DA (G), and w1118/THA;THK (G) guts. Scale bar = 30 μm.