Figure 1From: Photoperiodic diapause under the control of circadian clock genes in an insectThe properties of the cuticle deposition rhythm in Riptortus pedestris. (a) Cross sections of the tibia of the hind leg 20 days after adult emergence under short-day conditions. Alternating double layers are clearly observed in intact individuals. Arrows indicate bright layers. Scale bar: 25 μm. (b) The number of bright layers in the endocuticle under light-dark cycles at a constant temperature (25°C; closed circles), temperature cycles under constant darkness (open circles) and constant darkness at a constant temperature (open diamonds; N = 9-16). The solid and broken lines show regression lines calculated from the data from day 1 to day 8. On days 3 and 6 the numbers of bright layers under light-dark cycles were not significantly different from those under constant darkness (t-test, P > 0.05). The numbers of layers deposited under temperature cycles were one fewer than those under light-dark cycles, suggesting that the rhythm takes a little longer to entrain to temperature cycles. (c) The numbers of bright layers at day 6 (144 h after adult emergence) under light-dark cycles at 25°C (left) and temperature cycles under constant darkness (right; N = 11-16). The solid lines show hyperbolae, which are the equations when the rhythm completely entrains to the environmental cycles. The data of T = 24 in the left panel were from (b). Asterisks indicate significant differences between the mean number of bright layers and the hypothesized value (t-test, ** P < 0.01). (d) The number of bright layers on day 6 at 22.5°C, 25°C and 27.5°C under constant darkness. There were no significant differences in the number of bright layers among three temperatures (ANOVA, P > 0.05). N = 11-13. The data at 25°C are from (b). The Q10 value was 1.03.Back to article page