Figure 4.

Initial rates of CO₂ uptake in relation to the CO₂ concentration in the external medium in Synechococcus sp. strain PCC7002. ○, Cells grown continuously on 20 μL of CO₂ L⁻¹ (low-Ci cells); □, cells grown continuously on 2% CO₂ (high-Ci cells); •, high-Ci cells subjected to the fast-induction protocol for 4 min in the presence of CA (100 units mL⁻¹). Thereafter, an aliquot of cells containing 10 to 20 μg of Chl was centrifuged and resuspended in 4 mL of fresh CO₂-free assay buffer to yield a final [Chl] of 2.5 to 5 μg mL⁻¹. To fully inhibit CA activity 50 μm AZA was added and initial CO₂ uptake was measured mass spectrometrically.