Carbon fixation and carbonic anhydrase activity in Haslea ostrearia (Bacillariophyceae) in relation to growth irradiance |
| |
Authors: | M Rech A Morant-Manceau G Tremblin |
| |
Institution: | (1) Laboratoire de Physiologie et de Biochimie Végétales (EA 2160, “Mer, Molécules, Santé”), Faculté des Sciences et Techniques, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans CEDEX 9, France |
| |
Abstract: | The metabolic pathway of primary carbon fixation was studied in a peculiar pennate marine diatom, Haslea ostrearia (Bory) Simonsen, which synthesizes and accumulates a blue pigment known as “marennine”. Cells were cultured in a semi-continuous
mode under saturating 350 μmol(photon) m−2 s−1] or non-saturating 25 μmol(photon) m−2 s−1] irradiance producing “blue” (BC) and “green” (GC) cells, characterized by high and low marennine accumulation, respectively.
Growth, pigment contents (chlorophyll a and marennine), 14C accumulation in the metabolites, and the carbonic anhydrase (CA) activity of the cells were determined during the exponential
growth phase. Growth rate and marennine content were closely linked to irradiance during growth: higher irradiance increased
both growth rate and marennine content. On the other hand, the Chl a concentration was lower under saturating irradiance. The distribution between the Calvin-Benson (C3) and β-carboxylation (C4) pathways was very different depending on the irradiance during growth. Metabolites of the C3 cycle contained about 70 % of the total fixed radioactivity after 60 s of incorporation into cells cultured under the non-saturating
irradiance (GC), but only 47 % under saturating irradiance (BC). At the same time, carbon fixation by β-carboxylation was
24 % in GC versus about 41 % in BC, becoming equal to that in the C3 fixation pathway in the latter. Internal CA activity remained constant, but the periplasmic CA activity was higher under
low than high irradiance. |
| |
Keywords: | 14C C3 and C4 plants chlorophyll metabolic pathways |
本文献已被 SpringerLink 等数据库收录! |
|