Figure 1.
Changes in free-running circadian rhythms in old fish under LL and DD conditions
(A) Experimental setup of a video-based circadian rhythm measurement system under free-running conditions.
(B) Representative images of fish movement during the subjective day and night. Cumulative fish movements are presented as a heatmap.
(C–F) (C and E) The mean velocity of young (6 weeks old) and old (14 weeks old) fish, respectively, under LL (C) and DD (E) free-running conditions. Blue and red dots represent individual young and old fish, respectively. The gray (C) and the dark gray backgrounds (E) denote subjective night. CT denotes “Circadian time.” (D and F) Characterization of circadian rhythmicity of young and old fish under LL (D) and DD (F). The rhythmic behavior of individual fish was analyzed with JTK_CYCLE (Adj. p < 0.1, see Table S1). For amplitude, data are expressed as the mean ± SD, ∗p < 0.05.