Fig. 5. Effects of colchicine on luminal pH. The columns show luminal pH in the upper vas deferens (UVD) of intact moths at Zeitgeber time 8 (Zt8-I), and in moths that were injected at Zt8 and evaluated at Zt12 after colchicine injection (Zt12-C) or solvent injection (Zt12-S). pH remained high in colchicine-injected moths, but declined significantly (Student’s t-test; P<0.05) in solvent-injected moths. Each column represents the pH (mean ± S.E.M.) for 5–6 individuals per treatment.