CO2 syndrome in Chlorella

1991 ◽  
Vol 69 (5) ◽  
pp. 1003-1007 ◽  
Author(s):  
Mikio Tsuzuki ◽  
Shigetoh Miyachi

Effects of CO2 concentration on microalgae, especially on Chlorella, are discussed from the aspect of the high affinity of microalgae for inorganic carbon (Ci) in photosynthesis. Accumulation of Ci and carbonic anhydrase are the two main factors underlying the high affinity for Ci. The other factors such as development of carboxysomes and pyrenoids under low CO2 conditions may also be important. Contribution of each factor to the high affinity for Ci in photosynthesis seems to differ from species to species. Key words: Chlorella, inorganic carbon transport, carbonic anhydrase, fatty acids composition, CO2.

1991 ◽  
Vol 69 (5) ◽  
pp. 1032-1039 ◽  
Author(s):  
M. J. Merrett

Inorganic carbon transport was investigated in a range of marine microalgae. A small-celled strain of Stichococcus bacillaris, containing appreciable carbonic anhydrase activity, showed a high affinity for CO2, while measurement of the internal inorganic carbon pool by the silicone oil layer centrifugal filtering technique showed cells concentrated inorganic carbon up to 20-fold in relation to the external medium at pH 5.0 but not pH 8.3. The addition of 14CO2 or H14CO3− to cells in short-term kinetic experiments at pH 8.3 confirmed that only CO2 provides the exogenous substrate for substantial inorganic carbon accumulation within the cell. High-affinity HCO3− transport in Phaeodactylum tricornutum and Porphyridium purpureum is dependent on sodium ions, while intracellular carbonic anhydrase increased the steady-state flux of CO2 from inside the plasmalemma to Rubisco. In the presence of HCO3− the intracellular pH in cells of P. purpureum is 7.1 but on carbon starvation the pH falls to 6.0. Ethoxyzolamide blocks bicarbonate-dependent alkalinization of the cytosol, confirming a central role for carbonic anhydrase–bicarbonate in cytosolic pH regulation. Carbonic anhydrase activity is pH dependent in P. purpureum so synergistic interaction between CO2 uptake and bicarbonate transport may occur.


2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Marta del Puerto ◽  
M. Cristina Cabrera ◽  
Ali Saadoun

This investigation evaluated, in broiler chickensPectoralisandGastrocnemiusmuscles, the effect of the dietary supplementation with sodium selenite (0.3 ppm) versus selenomethionine (0.3 ppm), on the fatty acids composition, lipids indices, and enzymes indexes for desaturase, elongase, and thioesterase. The selenium reduced, in both muscles, the content of atherogenic fatty acids, C14:0 and C16:0, while it increased the C18:1 level. On the other hand, selenium increased, in both muscles, the content of C18:3n3 and EPA, but not DPA and DHA. No selenium effect was detected for PUFA/SFA, n-6, n-3, n-6/n-3, and atherogenic and thrombogenic indices. As for the enzyme indexes, a selenium effect is only detected for thioesterase. Taken together, the results highlight the potential effect of dietary selenium, mainly selenomethionine, in the modulation of the composition of fatty acids in chicken meat, in particular, reducing the content of atherogenic fatty acids and increasing the health promoting n-3 PUFA.


1998 ◽  
Vol 76 (6) ◽  
pp. 1072-1083 ◽  
Author(s):  
Yusuke Matsuda ◽  
Gale G. Bozzo ◽  
Brian Colman

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