INORGANIC CARBON TRANSPORT IN RELATION TO CULTURE AGE AND INORGANIC CARBON CONCENTRATION IN A HIGH-CALCIFYING STRAIN OF <em>EMILIANIA HUXLEYI</em> (PRYMNESIOPHYCEAE).

Nimer, Nabil A.; Merrett, Michael J.; Brownlee, Colin

The relationships among inorganic carbon transport, bicarbonate availability, pH, and culture age were investigated in high-calcifying cultures of Emiliania huxleyi (Lohmann) Hay & Mohler. Measurement of inorganic carbon transport by the silicone-oil centrifugation technique demonstrated that gadolinium, a potential Ca[sup2 ] channel inhibitor, blocked intracellular inorganic carbon uptake and photosynthetic 14CO[sub2] fixation in exponential-phase cells. In stationary-phase cells, the intracellular inorganic carbon concentration was unaffected by gadolinium. Gadolinium was also used to investigate the link between bicarbonate and Ca[sup2 ] transport in high-calcifying cells of E.huxleyi. Bicarbonate availability had significant and rapid effects on pH in exponential but not in stationary-phase cells, 4',4'-Diisothiocyanostilbene-2,2'-disulfonic acid did not block bicarbonate uptake from the external medium by exponential-phase cells. Inorganic carbon utilization by exponential-and stationary-phase cells of Emiliania huxleyi was investigated using a pH drift technique in a closed system. Light-dependent alkalization of the medium by stationary-phase cells resulted in a final pH of 10.1 and was inhibited by dextran-bound sulphonamide, an inhibitor of external carbonic anhydrase. Exponential-phase cells did not generate a pH drift. Overall, the results suggest that for high calcifying cultures of E.huxleyi the predominant pathway of inorganic carbon utilization differs in exponential and stationary phase cells of the same culture.

COCCOLITHUS huxleyi; PRYMNESIOPHYCEAE; COCCOLITHUS; ALGAE; CALCIFICATION; CARBON

Journal of Phycology, 1996, Vol 32, Issue 5, p813

0022-3646

Academic Journal

10.1111/j.0022-3646.1996.00813.x