Foraminifera promote calcification by elevating their intracellular pH
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- Lennart Jan de Nooijer
- Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
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- Takashi Toyofuku
- Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
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- Hiroshi Kitazato
- Institute of Biogeosciences, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
書誌事項
- 公開日
- 2009-09-08
- DOI
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- 10.1073/pnas.0904306106
- 公開者
- Proceedings of the National Academy of Sciences
この論文をさがす
説明
<jats:p> Surface seawaters are supersaturated with respect to calcite, but high concentrations of magnesium prevent spontaneous nucleation and growth of crystals. Foraminifera are the most widespread group of calcifying organisms and generally produce calcite with a low Mg content, indicating that they actively remove Mg <jats:sup>2+</jats:sup> from vacuolized seawater before calcite precipitation. However, one order of foraminifera has evolved a calcification pathway, by which it produces calcite with a very high Mg content, suggesting that these species do not alter the Mg/Ca ratio of vacuolized seawater considerably. The cellular mechanism that makes it possible to precipitate calcite at high Mg concentrations, however, has remained unknown. Here we demonstrate that they are able to elevate the pH at the site of calcification by at least one unit above seawater pH and, thereby, overcome precipitation-inhibition at ambient Mg concentrations. A similar result was obtained for species that precipitate calcite with a low Mg concentration, suggesting that elevating the pH at the site of calcification is a widespread strategy among foraminifera to promote calcite precipitation. Since the common ancestor of these two groups dates back to the Cambrian, our results would imply that this physiological mechanism has evolved over half a billion years ago. Since foraminifera rely on elevating the intracellular pH for their calcification, our results show that ongoing ocean acidification can result in a decrease of calcite production by these abundant calcifyers. </jats:p>
収録刊行物
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- Proceedings of the National Academy of Sciences
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Proceedings of the National Academy of Sciences 106 (36), 15374-15378, 2009-09-08
Proceedings of the National Academy of Sciences
