16E to comma stages of embryogenesis is the temperature-sensitive period crucial for larval HTA. (A-D) lin-15B (A), lin-35 (B), lin-54 (C) and met-2 (D) L4 P0 hermaphrodites were placed at 20°C for upshift or 26°C for downshift experiments. Two-cell embryos were dissected from P0 worms, and upshifted (orange) or downshifted (green) at 4E, 8E, 16E, comma, pretzel or L1 stage and scored for L1 larval arrest (n=60-78/point). Error bars represent standard error of the proportion. (E-G) Mean fluorescent intensity of PGL-1 expression was determined for L1 wild-type, lin-15B and lin-54 embryos that were downshifted at 8E (E), 16E (F) or comma (G) stage (n=20 L1/stage and temperature). Each symbol represents an individual worm, black lines represent the mean fluorescent intensity of the population. (*P<0.01, two-way ANOVA.) See also Fig. S2.