Fig. 2.

Light-induced O₂ evolution and uptake. C6 (A) and sta6 (B) were cultured photoautotrophically, bubbled with 2% CO₂ in air, and maintained in continuous light of 100 μmol photons⋅m⁻²⋅s⁻¹. Gross O₂ production (¹⁶O₂ evolution, green curve) and light-induced uptake of O₂ (¹⁸O₂ uptake, red curve) were monitored for 6 min using MIMS at four different light intensities (50, 150, 300, and 1,000 μmol photons⋅m⁻²⋅s⁻¹, as indicated in the upper right of each graph). Before turning on the light, the cells were maintained for 5 min in the dark (black bars on the top, left of each graph), and for an additional 3 min in the dark following the illumination (black bar, on the top, right of each graph). Gross O₂ uptake and both gross and net (blue curve) O₂ production were calculated according to the formula given in Materials and Methods. Each trace represents an average of at least three biological replicates ± SE.