Figure 6.

Ca²⁺ Flux into Chloroplast Stroma as a Function of Circadian Time.

Seedlings were germinated and grown in LD 16:8 until the time of treatment with coelenterazine, as described in Methods. After the 8-h treatment with coelenterazine in DD, the seedlings were transferred to LL. The protocol from the onset of LL was as shown in the inset: MAQ 6.3 seedlings were maintained in LL for 5 days (22 μE·m⁻²·s⁻¹), after which they were transferred to DD at different phases of the circadian cycle. The ordinate plots the integrated luminescence (0 to 90 min after the LL-to-DD transition) for four separate experiments, and the abscissa shows the circadian time (CT) of the transfer to darkness (time 0 is subjective dawn, which is the time of transfer in the experiments depicted in Figures 1 to 4). The solid line connects the averages, and the error bars indicate standard error of mean. The large variation at circadian time 8 was caused by one outlying point.