title: Proton pumping accompanies calcification in foraminifera.
abstract: Ongoing ocean acidification is widely reported to reduce the ability of calcifying marine organisms to produce their shells and skeletons. Whereas increased dissolution due to acidification is a largely inorganic process, strong organismal control over biomineralization influences calcification and hence complicates predicting the response of marine calcifyers. Here we show that calcification is driven by rapid transformation of bicarbonate into carbonate inside the cytoplasm, achieved by active outward proton pumping. Moreover, this proton flux is maintained over a wide range of pCO2levels. We furthermore show that a V-type H+ATPase is responsible for the proton flux and thereby calcification. External transformation of bicarbonate into CO2due to the proton pumping implies that biomineralization does not rely on availability of carbonate ions, but total dissolved CO2may not reduce calcification, thereby potentially maintaining the current global marine carbonate production.
authors.affiliation: Department of Marine Biodiversity Research (B-DIVE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Natsushima-cho 2-15, Yokosuka 237-0061, Japan.
authors.forename: Takashi
authors.identifier: 0000-0001-8095-6077
authors.initials: T
authors.lastname: Toyofuku
authors.affiliation: Department of Mathematical Science and Advanced Technology (MAT), Yokohama Institute for Earth Sciences (YES), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 3173-25, Showa-machi, Kanazawa-ku, Yokohama-City, Kanagawa 236-0001, Japan.
authors.forename: Miki Y
authors.initials: MY
authors.lastname: Matsuo
authors.affiliation: Department of Ocean Systems, NIOZ-Royal Netherlands Institute for Sea Research and Utrecht University, Landsdiep 4, 1797 SZ 't Horntje, The Netherlands.
authors.forename: Lennart Jan
authors.initials: LJ
authors.lastname: de Nooijer
authors.affiliation: Department of Marine Biodiversity Research (B-DIVE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Natsushima-cho 2-15, Yokosuka 237-0061, Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Nagai
authors.affiliation: Department of Marine Biodiversity Research (B-DIVE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Natsushima-cho 2-15, Yokosuka 237-0061, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Kawada
authors.affiliation: Department of Physics and Earth Sciences, Faculty of Science and Tropical Biosphere Research Center, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Fujita
authors.affiliation: Department of Ocean Systems, NIOZ-Royal Netherlands Institute for Sea Research and Utrecht University, Landsdiep 4, 1797 SZ 't Horntje, The Netherlands.|Department of Earth Sciences - Geochemistry, Faculty of Geosciences, Utrecht University, P.O. Box 80.021, 3508 TA Utrecht, The Netherlands.
authors.forename: Gert-Jan
authors.initials: GJ
authors.lastname: Reichart
authors.affiliation: Department of Biogeochemistry, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Natsushima-cho 2-15, Yokosuka 237-0061, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Nomaki
authors.affiliation: Department of Marine Biodiversity Research (B-DIVE), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Natsushima-cho 2-15, Yokosuka 237-0061, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Tsuchiya
authors.affiliation: Department of Mathematical Science and Advanced Technology (MAT), Yokohama Institute for Earth Sciences (YES), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 3173-25, Showa-machi, Kanazawa-ku, Yokohama-City, Kanagawa 236-0001, Japan.
authors.forename: Hide
authors.initials: H
authors.lastname: Sakaguchi
authors.affiliation: Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato-ku, Tokyo 108-8477, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitazato
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000378:metabolism*; D002113:Calcification, Physiologic; D057486:Carbon Cycle / Q000502:physiology; D002245:Carbon Dioxide / Q000378:metabolism; D002254:Carbonates / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D056908:Foraminifera / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009792:Oceans and Seas; D017494:Proton Pumps / Q000378:metabolism; D011522:Protons; D012623:Seawater / Q000737:chemistry*
chemical_list: D002254:Carbonates; D017494:Proton Pumps; D011522:Protons; D002245:Carbon Dioxide