| 41. |
- PALMQVIST, K, et al.
(författare)
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ROLE OF CARBONIC-ANHYDRASE IN ASSIMILATION OF INORGANIC CARBON IN DUNALIELLA-SALINA
- 1991
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Ingår i: SOVIET PLANT PHYSIOLOGY. - 0038-5719. ; 38:3, s. 339-345
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Tidskriftsartikel (refereegranskat)abstract
- We studied changes in the rate of photosynthetic assimilation of inorganic carbon (C(i)) in relation to CO2 concentration by Dunaliella salina cells adapted to high (5%) and low (0.03%) concentrations of CO2. It is demonstrated that the rate of C(i) assimilation was higher in algae adapted to 0.03% CO2 than in culture adapted to 0.03% CO2. The period of adaptation of D. salina to low CO2 concentrations lasted 5-6 h, during which time activity of carbonic anhydrase (CA) increased on the cell surface and inside cells. Soluble CA (sCA) was detected in D. salina, together with membrane-bound CA of cytoplasmic (cCA) and thylakoid (tCA) membranes. The effect of CA inhibitors - acetazolamide (AZA) and ethoxyzolamide (EZA) - on photosynthesis of D. salina cells was studied in the work. It turned out that EZA lowered the rate of O2 evolution in algae adapted to 5% CO2 and totally suppressed this process in algae adapted to 0.03% CO2. Acetazolamide lowered the photosynthetic rate only in algae adapted to 0.03% CO2. It is concluded that intracellular forms of CA are needed for functioning of the C1-concentration mechanism in algae adapted to conditions of carbon dioxide limitation of photosynthesis. The authors discuss the mechanisms of adaptation of D. salina to low CO2 concentrations and the role played by CA in this process.
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| 42. |
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| 43. |
- Park, Y I, et al.
(författare)
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Role of a novel photosystem II-associated carbonic anhydrase in photosynthetic carbon assimilation in Chlamydomonas reinhardtii
- 1999
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Ingår i: FEBS Letters. - 0014-5793 .- 1873-3468. ; 444:1, s. 102-105
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Tidskriftsartikel (refereegranskat)abstract
- Intracellular carbonic anhydrases (CA) in aquatic photosynthetic organisms are involved in the CO2-concentrating mechanism (CCM), which helps to overcome CO2 limitation in the environment. In the green alga Chlamydomonas reinhardtii, this CCM is initiated and maintained by the pH gradient created across the chloroplast thylakoid membranes by photosystem (PS) II-mediated electron transport. We show here that photosynthesis is stimulated by a novel, intracellular alpha-CA bound to the chloroplast thylakoids. It is associated with PSII on the lumenal side of the thylakoid membranes. We demonstrate that PSII in association with this lumenal CA operates to provide an ample flux of CO2 for carboxylation. (C) 1999 Federation of European Biochemical Societies.
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| 44. |
- Pawlik, B, et al.
(författare)
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pH-dependent cadmium transport inhibits photosynthesis in the cyanobacterium Synechocystis aquatilis
- 1993
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Ingår i: Environmental and Experimental Botany. - 0098-8472 .- 1873-7307. ; 33:2, s. 331-337
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Tidskriftsartikel (refereegranskat)abstract
- Short-term (5-120 sec) transport of cadmium (Cd-109) into cells of the unicellular cyanobacterium Synechocystis aquatilis was studied using a rapid filtration technique. The transport was strongly pH-dependent, occurring at pH 7, but not at pH 5.5, and was also observed in long-term (40 min) experiments. For this process the optimum pH was approximately 7.5; uptake was considerably reduced at lower pHs. The entrance of cadmium disturbed photosynthetic activity and related processes. At pH 7, cadmium (8.9 muM) decreased CO2 fixation by about 55%, inhibited carbonic anhydrase activity (completely in intact cells, by 65%, in cell-free extracts) and photosynthetic O2-evolution by about 50%. At pH 5.5 no effects were observed.
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| 45. |
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| 46. |
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| 47. |
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| 48. |
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| 49. |
- Renberg, Linda, et al.
(författare)
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A metabolomic approach to study major metabolite changes during acclimation to limiting CO2 in chlamydomonas reinhardtii
- 2010
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 154:1, s. 187-196
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Tidskriftsartikel (refereegranskat)abstract
- Using a gas chromatography-mass spectrometry-time of flight technique, we determined major metabolite changes during induction of the carbon-concentrating mechanism in the unicellular green alga Chlamydomonas reinhardtii. In total, 128 metabolites with significant differences between high-and low-CO2-grown cells were detected, of which 82 were wholly or partially identified, including amino acids, lipids, and carbohydrates. In a 24-h time course experiment, we show that the amino acids serine and phenylalanine increase transiently while aspartate and glutamate decrease after transfer to low CO2. The biggest differences were typically observed 3 h after transfer to low-CO2 conditions. Therefore, we made a careful metabolomic examination at the 3-h time point, comparing low-CO2 treatment to high-CO2 control. Five metabolites involved in photorespiration, 11 amino acids, and one lipid were increased, while six amino acids and, interestingly, 21 lipids were significantly lower. Our conclusion is that the metabolic pattern during early induction of the carbon-concentrating mechanism fit a model where photorespiration is increasing.
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| 50. |
- Richardson, Katherine, et al.
(författare)
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The relationship between photosynthesis measured by C-14 incorporation and by uptake of inorganic carbon in unicellular algae
- 1984
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Ingår i: Journal of Experimental Marine Biology and Ecology. - : Elsevier BV. - 0022-0981 .- 1879-1697. ; 81:3, s. 241-250
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Tidskriftsartikel (refereegranskat)abstract
- The traditional 14C method of estimating photosynthetic rates was compared with net photo-synthesis in two species of unicellular algae. Net photosynthesis was defined as the disappearance of inorganic carbon from the algal medium and was determined using a described infra-red gas analyser (IRGA) technique. For Amphidinium carterae Hulbert, the 14C method always led to lower calculated rates of photosynthesis than the IRGA technique. This difference was, on average, ≈100%. For Scenedesmusobliquus (Turpin) Kützing, the 14C method could lead to over-estimates, good agreement with, or underestimates of net photosynthesis. Although the under-estimates were only of the order of 15%, the over-estimates were in some cases > 100%. There is some indication that respiration rate is an important factor in the relationship between photosynthetic rates calculated by the two methods for this organism.
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