Low temperature reduces the energetic requirement for the CO2 concentrating mechanism in diatoms. Issue 1 (13th October 2014)

• Record Type: Journal Article
• Authors: Kranz, Sven A.; Young, Jodi N.; Hopkinson, Brian M.; Goldman, Johanna A. L.; Tortell, Philippe D.; Morel, François M. M.
• Is Part Of: New phytologist. Volume 205:Issue 1(2015)
• Page Start: 192
• Page End: 201
• Publication Date: 2014-10-13
• Subjects: Botany -- Periodicals; 580
• DOI: 10.1111/nph.12976
• Languages: English
• ISSNs: 0028-646X

Abstract

<abstract abstract-type="main" id="nph12976-abs-0001"> <title>Summary</title> <p> <list id="nph12976-list-0001" list-type="bullet"> <list-item> <p>The goal of this study is to investigate the CO<sub>2</sub> concentrating mechanism (CCM) of the dominant phytoplankton species during the growing season at Palmer station in the Western Antarctic Peninsula.</p> </list-item> <list-item> <p>Key CCM parameters (cellular half‐saturation constants for CO<sub>2</sub> fixation, carbonic anhydrase activity, CO<sub>2</sub>/HCO<sub>3</sub><sup>−</sup> uptake, δ<sup>13</sup>C<sub>org</sub>) in natural phytoplankton assemblages were determined. Those results, together with additional measurements on CO<sub>2</sub> membrane permeability from <italic>Fragilariopsis cylindrus</italic> laboratory cultures, were used to develop a numerical model of the CCM of cold water diatoms.</p> </list-item> <list-item> <p>The field data demonstrate that the dominant species throughout the season possess an effective CCM, which achieves near saturation of CO<sub>2</sub> for fixation. The model provides a means to examine the role of eCA activity and HCO<sub>3</sub><sup>−</sup>/CO<sub>2</sub> uptake in the functioning of the CCM. According to the model, the increase in δ<sup>13</sup>C<sub>org</sub> during the bloom results chiefly from decreasing ambient CO<sub>2</sub> concentration (which reduces the gross diffusive flux across the membrane) rather than a shift in inorganic carbon uptake from CO<sub>2</sub> to HCO<sub>3</sub><sup>−</sup>.</p> </list-item> <list-item> <p>The CCM of diatoms in the Western Antarctic Peninsula functions with a relatively small expenditure of energy, resulting chiefly from the low half‐saturation constant for Rubisco at cold temperatures.</p> </list-item> </list> </p> </abstract>