Publication Type: | Journal Article |
Year of Publication: | 2008 |
Authors: | S. Trimborn, Lundholm, N., Thoms, S., Richter, K. U., Krock, B., Hansen, P. J., Rost, B. |
Journal: | Physiologia Plantarum |
Volume: | 133 |
Pagination: | 92-105 |
Date Published: | May |
ISBN Number: | 0031-9317 |
Keywords: | anhydrase activity, chlamydomonas-reinhardtii, co2 concentrating mechanisms, co2-concentrating mechanisms, cyanobacterium synechococcus pcc7942, domoic acid production, emiliania-huxleyi, eukaryotic algae, isotope fractionation, marine-phytoplankton |
Abstract: | The effects of pH-induced changes in seawater carbonate chemistry on inorganic carbon (C-i) acquisition and domoic acid (DA) production were studied in two potentially toxic diatom species, Pseudo-nitzschia multiseries and Nitzschia navis-varingica, and the non-toxic Stellarima stellaris. In vivo activities of carbonic anhydrase (CA), photosynthetic O-2 evolution and CO2 and HCO3- uptake rates were measured by membrane inlet MS in cells acclimated to low (7.9) and high pH (8.4 or 8.9). Species-specific differences in the mode of carbon acquisition were found. While extracellular carbonic anhydrase (eCA) activities increased with pH in P. multiseries and S. stellaris, N. navis-varingica exhibited low eCA activities independent of pH. Half-saturation concentrations (K-1/2) for photosynthetic O-2 evolution, which were highest in S. stellaris and lowest in P. multiseries, generally decreased with increasing pH. In terms of carbon source, all species took up both CO2 and HCO3-. K-1/2 values for inorganic carbon uptake decreased with increasing pH in two species, while in N. navis-varingica apparent affinities did not change. While the contribution of HCO3- to net fixation was more than 85% in S. stellaris, it was about 55% in P. multiseries and only approximately 30% in N. navis-varingica. The intracellular content of DA increased in P. multiseries and N. navis-varingica with increasing pH. Based on our data, we propose a novel role for eCA acting as C-i-recycling mechanism. With regard to pH-dependence of growth, the ’HCO3- user’ S. stellaris was as sensitive as the ’CO2 user’ N. navis-varingica. The suggested relationship between DA and carbon acquisition/C-i limitation could not be confirmed. |
URL: | <Go to ISI>://000254811600011 |
Inorganic carbon acquisition in potentially toxic and non-toxic diatoms: the effect of pH-induced changes in seawater carbonate chemistry
Taxonomic name:
Pseudo-nitzschia multiseries (Hasle) Hasle (Taxonomy), Pseudo-nitzschia multiseries (Hasle) Hasle (Taxonomy), Pseudo-nitzschia multiseries (Hasle) Hasle (Taxonomy), Pseudo-nitzschia multiseries (Hasle) Hasle (Taxonomy), Nitzschia navis-varingica Lundholm & Moestrup (Taxonomy), Pseudo-nitzschia multiseries (Hasle) Hasle (Taxonomy), Pseudo-nitzschia (Taxonomy)