Dim scotopic illumination accelerates the reentrainment following simulated jetlags in a diurnal experimental model, Drosophila

Figures & data

Figure 1. Entrainment and free-run in D. biarmipes. The actograms of the representative control and experimental males of D. biarmipes which were entrained by LD 12:12 (A) and LS 12:12 (C) cycles, respectively, and then transferred to DD on the day 11 (oblique arrow). The mean activity profiles of 49 control (B) and experimental (D) males during the entrainment are showing the circadian peaks (dark arrows), the masking peaks (open arrows) and the phase relationship between the Aoff of the M peak and Aon of the E peak (Ψ_M-E). The dark and open time bars denote the photophase (300 lx) and scotophase (0 lx), respectively, the long dark time bars denote DD and the hatched portion of the time-bars denotes the dim nocturnal irradiance at 0.03 lx.

Table 1. Effects of the lighting schedules with dark nights (Control Expt.) and dimly-lit nights (LAN Expt.) on the features of entrainment and free-running rhythmicity of D. biarmipes.

Parameters	Control Expt.	LAN Expt.
ψo	0.5 ± 0.2	2.9 ± 0.6
ψe	-0.5 ± 0.3	0
ψM-E	4.6 ± 1.1	8.4 ± 1.3
α-Ent	13.1 ± 0.9	14.9 ± 1.1
ρ-Ent	10.9 ± 0.7	9.1 ± 0.8
AL-Ent       α-DD       ρ-DD       τ       AL-DD	762 ± 59       7.2 ± 1.1       17.1 ± 1.6       24.2 ± 0.8       439 ± 62	1321 ± 103       9.6 ± 1.2       12.9 ± 1.3       22.6 ± 1.5       687 ± 59

Values are given in hours (mean ± SD, n = 49 flies). ψo, the phase angle difference between the activity onset and lights-on; ψe, the phase angle difference between the activity offset and lights-off; ψ_M-E, the phase relationship (i.e., the interval) between the morning and evening activity peaks; α-Ent, duration of activity during entrainment; ρ-Ent, duration of rest during entrainment; αDD, duration of activity during free-run in DD; ρ-DD, duration of rest during free-run in DD; τ, the period of free-running rhythm in DD; AL-DD, the activity level in DD. All values of the LAN Expt. are significantly different from the corresponding values of the Control Expt. (p < 0.001).

Figure 2. Simulated advance and delay jetlags in D. biarmipes. The actograms of the four representative males of D. biarmipes which were subjected to 8 h phase advance and delay of LD 12:12 cycles (A and C, respectively) and LS 12:12 cycles (B and D, respectively).

Figure 3. Transients after advance and delay jetlags. Advancing and delaying transients (mean ± S.D., n = 49 flies) endured by the activity onsets (Aon-LD) and offsets (Aoff-LD) of the control males and that of the experimental males (Aon-LS and Aoff-LS) of D. biarmipes following the advance (A) and delay shift (B) in the lighting schedules. The asterisks denote the statistically significant effects of the dim nocturnal illumination (p < 0.001).