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Model for HCO/sub 3//sup -/ accumulation and photosynthesis in the cyanobacterium Synechococcus sp: theoretical predictions and experimental observations

Journal Article · · Plant Physiol.; (United States)
OSTI ID:5818141
; ;
A simple model based on HCO/sub 3//sup -/ transport has been developed to relate photosynthesis and inorganic carbon fluxes for the marine cyanobacterium, Synechococcus sp. Naegeli (strain RRIMP N1). Predicted relationships between inorganic carbon transport, CO/sub 2/ fixation, internal carbonic anhydrase activity, and leakage of CO/sub 2/ out of the cell, allow comparisons to be made with experimentally obtained data. Measurements of inorganic carbon fluxes and internal inorganic carbon pool sizes in these cells were made by monitoring time-courses of CO/sub 2/ changes (using a mass spectrometer) during light/dark transients. At just saturating CO/sub 2/ conditions, total inorganic carbon transport did not exceed net CO/sub 2/ fixation by more than 30%. This indicates CO/sub 2/ leakage similar to that estimated for C/sub 4/ plants. For this leakage rate, the model predicts the cell would need a conductance to CO/sub 2/ of around 10/sup -5/ centimeters per second. The model predicts that carbonic anhydrase is necessary internally to allow a sufficiently fast rate of CO/sub 2/ production to prevent a large accumulation of HCO/sub 3//sup -/. Intact cells show light stimulated carbon anhydrase activity when assayed using /sup 18/O-labeled CO/sub 2/ techniques.
Research Organization:
Australian National Univ., Canberra
OSTI ID:
5818141
Journal Information:
Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 77:2; ISSN PLPHA
Country of Publication:
United States
Language:
English

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Related Subjects

551000* -- Physiological Systems
59 BASIC BIOLOGICAL SCIENCES
ACID CARBONATES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBON-OXYGEN LYASES
CARBONIC ANHYDRASE
CHALCOGENIDES
CHEMICAL REACTIONS
CYANOBACTERIA
ENZYMES
EVEN-EVEN NUCLEI
HYDRO-LYASES
ISOTOPES
LIGHT NUCLEI
LYASES
MEMBRANE TRANSPORT
MICROORGANISMS
NUCLEI
OXIDES
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
STABLE ISOTOPES
SYNTHESIS