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HCO 3 − and CO 2 leakage from Synechococcus UTEX 625
Author(s) -
SALON C.,
MIR N. A.,
CANVIN D. T.
Publication year - 1996
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1996.tb00249.x
Subject(s) - chemistry , carbon dioxide , efflux , total inorganic carbon , darkness , synechococcus , quenching (fluorescence) , dissolved organic carbon , analytical chemistry (journal) , nuclear chemistry , chromatography , biochemistry , environmental chemistry , cyanobacteria , botany , fluorescence , biology , organic chemistry , physics , genetics , bacteria , quantum mechanics
The leakage of various inorganic carbon species from air‐grown cells of Synechococcus UTEX 625 was investigated after a light to dark transition or during a light period using a mass spectrometer under a wide variety of experimental conditions. Total inorganic carbon efflux and CO 2 efflux during the initial period of darkness were measured with or without carbonic anhydrase in the reaction medium respectively. The HCO 3 − efflux after a light to dark transition was estimated by difference. Carbon dioxide efflux in the light was measured by inhibiting CO 2 transport with either Na 2 S or COS 3 or quenching the 13 C inorganic carbon transport by the addition of 12 C inorganic carbon in excess. In cells in which CO 2 fixation was inhibited, when only the HCO 3 − transport system was fully operative, CO 2 effluxed continuously during the light period at a rate equal to about 25% of that in darkness. When only the CO 2 transport system was operative, HCO 3 − effluxed during the light period. The difference between the light and dark efflux rates was consistent with a 0.6 unit decrease in the intracellular pH upon darkening the cells. The permeabilities of the cell for CO 2 (2.94 ± 0.14 ± 10 −8 ms −1 ; mean ± SE, n =137) and HCO 3 − (1.4–1.7 ± 10 −9 ms −1 ) were calculated.