Fig. 4.

O₂ evolution of DIC-starved cells, incubated with increasing concentrations of sodium bicarbonate (0.005–1 mM) in an illuminated oxygen electrode chamber. To enable a direct comparison between the different strains, data were expressed in fraction of maximum photosynthetic rate. Absolute maximum rates are given in Table 1. Pyrenoid-positive strains (wild type and helix AB) have a photosynthesis saturating at low levels of NaHCO₃, indicating the presence of a CCM. Legend: wild type (●), spinach hybrid (○), helix AB (▼), and reciprocal (▽).