Detection of a variable intracellular acid‐labile carbon pool in Thalassiosira weissflogii (Heterokontophyta) and Emiliania huxleyi (Haptophyta) in response to changes in the seawater carbon system. Issue 2 (7th October 2013)

• Record Type: Journal Article
• Authors: Isensee, Kirsten; Erez, Jonathan; Stoll, Heather M.
• Is Part Of: Physiologia plantarum. Volume 150:Issue 2(2014:Feb.)
• Page Start: 321
• Page End: 338
• Publication Date: 2013-10-07
• Subjects: Plant physiology -- Periodicals; 571.2
• DOI: 10.1111/ppl.12096
• Languages: English
• ISSNs: 0031-9317

Abstract

<abstract abstract-type="main" id="ppl12096-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p id="ppl12096-para-0001">Accumulation of an intracellular pool of carbon (C<sub>i</sub> pool) is one strategy by which marine algae overcome the low abundance of dissolved CO<sub>2</sub> (CO<sub>2</sub><sub>(aq)</sub>) in modern seawater. To identify the environmental conditions under which algae accumulate an acid‐labile C<sub>i</sub> pool, we applied a <sup>14</sup>C pulse‐chase method, used originally in dinoflagellates, to two new classes of algae, coccolithophorids and diatoms. This method measures the carbon accumulation inside the cells without altering the medium carbon chemistry or culture cell density. We found that the diatom <italic>Thalassiosira weissflogii</italic> [(Grunow) G. Fryxell & Hasle] and a calcifying strain of the coccolithophorid <italic>Emiliania huxleyi</italic> [(Lohmann) W. W. Hay & H. P. Mohler] develop significant acid‐labile C<sub>i</sub> pools. Ci pools are measureable in cells cultured in media with 2–30 µmol l<sup>−1</sup> CO<sub>2</sub><sub>(aq)</sub>, corresponding to a medium pH of 8.6–7.9. The absolute C<sub>i</sub> pool was greater for the larger celled diatoms. For both algal classes, the C<sub>i</sub> pool became a negligible contributor to photosynthesis once CO<sub>2</sub><sub>(aq)</sub> exceeded 30 µmol l<sup>−1</sup>. Combining the <sup>14</sup>C pulse‐chase method and <sup>14</sup>C disequilibrium method enabled us to assess whether <italic>E. huxleyi</italic> and <italic>T. weissflogii</italic> exhibited thresholds for foregoing accumulation of DIC or reduced the reliance on bicarbonate uptake with increasing CO<sub>2</sub><sub>(aq)</sub>. We showed that the C<sub>i</sub> pool decreases with higher CO<sub>2</sub>:HCO<sub>3</sub><sup>−</sup> uptake rates.</p> </abstract>