Figure 3. Daily rhythm of AANAT activity in chicken retinal cell cultures

Cultures were prepared from embryonic day 6 retinas and incubated as described in the legend to Figure 1. After incubation for 1 day at 37 °C, cells were cultured under LD at either 39 °C or 40 °C for six more days. Cells were harvested on days 4, 5, 6, and 7 in vitro (DIV 4 to 7) at ZT 6 and ZT 18. The horizontal bars on the bottom of the graph represent the periods of light (open bar) and darkness (filled bar). Data are shown as means with the error bars representing the SEM (N=3). Significant diurnal rhythms of AANAT activity were observed on each day from DIV 4-7 in cells incubated at 39 °C (p<0.01) and 40 °C (p<0.001). Daytime values were not significantly different at the two temperatures, but nighttime activity was significantly higher at 40 °C than at 39 °C on DIV 4 (p<0.001), DIV 5 (p=0.006), and DIV 6 (p=0.047).