Acquisition of inorganic carbon by the marine diatom Thalassiosira weissflogii

2002 ◽  
Vol 29 (3) ◽  
pp. 301 ◽  
Author(s):  
François M. M. Morel ◽  
Elizabeth H. Cox ◽  
Anne M. L. Kraepiel ◽  
Todd W. Lane ◽  
Allen J. Milligan ◽  
...  
Keyword(s):  
Inorganic Carbon ◽  
Marine Diatom ◽  
Published Data ◽  
Carbonic Anhydrases ◽  
Thalassiosira Weissflogii ◽  
Metal Centre ◽  
Natural Conditions ◽  
Major Species ◽  
Ambient Co2 ◽  
Inorganic Carbon Acquisition

Recent data on the physiology of inorganic carbon acquisition by the model marine diatom Thalassiosira weissflogii (Grunow) demonstrate the importance of the catalytic equilibration of HCO3-and CO2by carbonic anhydrases located in the periplasm and in the cytoplasm. These enzymes can use Zn, Co or Cd as their metal centre, and their activity increases at low ambient CO2. The silica frustule provides buffering for extracellular CA activity, The transmembrane transport of CO2 may occur by passive diffusion. Under CO2 limitation, the cytoplasmic HCO3–is used to form malate and oxaloacetic acid via phosphoenolpyruvate carboxylase. It appears that subsequent decarboxylation of these compounds in the chloroplast regenerates CO2 near the site of Rubisco, and thus provides the organism with an effective unicellular C4 photosynthetic pathway. These results, together with other published data, bring up two major questions regarding inorganic carbon acquisition in diatoms: What is the major species of inorganic carbon (CO2 or HCO3–) transported across the membrane under natural conditions? And what is the form of carbon (inorganic or organic) accumulated by the cells?

The role of the chloroplast in inorganic carbon acquisition by Chlamydomonas reinhardtii

1991 ◽  
Vol 69 (5) ◽  
pp. 1017-1024 ◽  
Author(s):  
James V. Moroney ◽  
Catherine B. Mason
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Inorganic Carbon ◽  
Published Data ◽  
Carbon Uptake ◽  
Intact Chloroplasts ◽  
Inorganic Carbon Transport ◽  
Inorganic Carbon Uptake ◽  
Carbon Transport ◽  
Inorganic Carbon Acquisition

The role of the chloroplast in algal inorganic carbon acquisition is reviewed. Unicellular green algae possess the ability to grow photoautotrophically at very low CO2 concentrations. The presence of a CO2-concentrating system that elevates the CO2 level within the cell can account for the algae's ability to reduce photorespiration and grow under these conditions. The mechanism of this inorganic carbon transport is unclear at present, although both the plasmalemma and the chloroplast have been implicated in this process. Three aspects of the role of the chloroplast in Chlamydomonas reinhardtii inorganic carbon uptake are discussed in this review. First, the present models of inorganic carbon uptake are summarized. Second, the purity and integrity of intact chloroplast preparations are discussed. Third, an evaluation of the published data on inorganic carbon uptake by isolated intact chloroplasts is presented. Key words: Chlamydomonas reinhardtii, carbonic anhydrase, chloroplast, active CO2 uptake.

Photosynthesis and inorganic carbon acquisition in the cyanobacterium Chlorogloeopsis sp. ATCC 27193

1997 ◽  
Vol 99 (1) ◽  
pp. 81-88
Author(s):  
Robert S. Skleryk ◽  
Pascal N. Tyrrell ◽  
George S. Espie
Keyword(s):  
Inorganic Carbon ◽  
Inorganic Carbon Acquisition

scholarly journals Response of the marine diatom Thalassiosira weissflogii to iron stress1

1986 ◽  
Vol 31 (5) ◽  
pp. 989-997 ◽  
Author(s):  
Gail I. Harrison ◽  
F. M. M. Morel
Keyword(s):  
Marine Diatom ◽  
Thalassiosira Weissflogii

Photosynthetic utilisation of inorganic carbon and its regulation in the marine diatom Skeletonema costatum

2004 ◽  
Vol 31 (10) ◽  
pp. 1027 ◽  
Author(s):  
Xiongwen Chen ◽  
Kunshan Gao
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Skeletonema Costatum ◽  
Co2 Concentration ◽  
Marine Diatom ◽  
Disulfonic Acid ◽  
High Co2 ◽  
Low Co2 ◽  
Diatom Skeletonema Costatum ◽  
Very High

Photosynthetic uptake of inorganic carbon and regulation of photosynthetic CO2 affinity were investigated in Skeletonema costatum (Grev.) Cleve. The pH independence of K1/2(CO2) values indicated that algae grown at either ambient (12 μmol L–1) or low (3 μmol L–1) CO2 predominantly took up CO2 from the medium. The lower pH compensation point (9.12) and insensitivity of photosynthetic rate to di-isothiocyanatostilbene disulfonic acid (DIDS) indicated that the alga had poor capacity for direct HCO3– utilisation. Photosynthetic CO2 affinity is regulated by the concentration of CO2 rather than HCO3–, CO32– or total dissolved inorganic carbon (DIC) in the medium. The response of photosynthetic CO2 affinity to changes in CO2 concentration was most sensitive within the range 3–48 μmol L–1 CO2. Light was required for the induction of photosynthetic CO2 affinity, but not for its repression, when cells were shifted between high (126 μmol L–1) and ambient (12 μmol L–1) CO2. The time needed for cells grown at high CO2 (126 μmol L–1) to fully develop photosynthetic CO2 affinity at ambient CO2 was approximately 2 h, but acclimation to low or very low CO2 levels (3 and 1.3 μmol L–1, respectively) took more than 10 h. Cells grown at low CO2 (3 μmol L–1) required approximately 10 h for repression of all photosynthetic CO2 affinity when transferred to ambient or high CO2 (12 or 126 μmol L–1, respectively), and more than 10 h at very high CO2 (392 μmol L–1).

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