Fig. 5.

Chemical compounds activate BmTRPA1 independently of heat, induce diapause, and increase body and cocoon-shell weight. (A) Effect of treatment with chemical compounds on diapause-egg–inducing activity. Eggs were incubated at 15DD with formalin, H₂O₂, and CA, and the percentage of diapause eggs produced by their progeny was calculated. The moths were divided into two groups: larvae that initiated spinning earlier (<50% of total larvae; early), and larvae that initiated spinning later (>50% of total larvae; late). (B and C) Effects on pupal and cocoon-shell weights. Eggs were incubated at 25 °C or 15 °C in the dark with or without 0.3% formalin. Pupae (B) and cocoon-shell (C) weights after 3 d of pupation are shown. In A–C, 15DD (n = 54), 25DD (n = 141), formalin (0.003%; n = 23, 0.03%; n = 46, 0.3%, n = 87), H₂O₂ (0.5 mM; n = 64, 5 mM; n = 68, 50 mM; n = 72), CA (0.01 mM; n = 52, 0.1 mM; n = 53, 1 mM; n = 44). Data represent means ± SD; ***P < 0.001, **P < 0.01, *P < 0.05. In A, lowercase letters indicate statistically significant differences in DW-treated vs. chemical-compound-treated animals (a), and early vs. late animals (b). (D–F) Temporal changes in current (Upper trace) in a BmTRPA1-expressing cell, and temperature (Lower trace) during temperature fluctuation without additional chemical compounds (D), with 0.01% formalin (E), and 10 mM H₂O₂ (F) during cooling in a whole-cell patch-clamp experiment. Membrane potential was held at −60 mV. Note that a sudden increase in current level was observed after H₂O₂ washout, probably because currents were still gradually developing at that time and were enhanced by the temperature increase.