Figure 2
From: Auto-flotation of heterocyst enables the efficient production of renewable energy in cyanobacteria
Photosystem II (PSII) activity assays using O2 evolution rate measurements and chlorophyll fluorescence analyses.
Cells in the logarithmic phase (A730: 0.8–1.0) were treated with DCMU (3-(3,4-dichlorophenyl)-1,1-dimethylurea) for 10 minutes prior to the analysis. (a) Photosynthetic O2 evolution rates of the Anabaena 7120 cells were analysed after treatment with DCMU using various concentrations ranging from 0.005 μM to 5.0 μM. BQ was supplemented as an electron acceptor at a final concentration of 2.0 μM. The O2 evolution rate of untreated (0 μM DCMU) cells was set as 100%. (b, c) The photochemical activity of PSII was represented as the change in chlorophyll fluorescence between untreated cells and 1.0 μM DCMU-treated cells. All of the tested samples were adjusted to 20 μg of chlorophyll per mL to measure their fluorescence. The images of fluorescence detected a visible decline in the quantum yield of PSII in DCMU-treated cells, which was detected by Imaging-PAM (see the Methods section). During this experiment, the ethanol-treated cells were added as a control because ethanol was used as a solvent for the DCMU treatment experiments. Error bars indicate s.d. values calculated from the average of triplicate experiments.
