Biological control of aragonite formation in stony corals

• Published in: Science (American Association for the Advancement of Science) Vol. 356; no. 6341; pp. 933 - 938
• Main Authors: Von Euw, Stanislas, Zhang, Qihong, Manichev, Viacheslav, Murali, Nagarajan, Gross, Juliane, Feldman, Leonard C., Gustafsson, Torgny, Flach, Carol, Mendelsohn, Richard, Falkowski, Paul G.
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 02-06-2017; The American Association for the Advancement of Science
• Subjects: Acidification; Amorphous materials; Animals; Anthozoa - growth & development; Anthozoa - physiology; Anthozoa - ultrastructure; Aragonite; Attachment; Biological control; Calcification; Calcification, Physiologic - physiology; Calcium Carbonate - metabolism; Carbon dioxide; Carbonates - analysis; Cellular Microenvironment - physiology; Chemical precipitation; Construction; Corals; Crystal growth; Crystal structure; Crystallization; Deposition; Enrichment; Hypotheses; Imaging; Magnetic Resonance Spectroscopy; Microenvironments; Microscopy, Electron, Scanning; Minerals; Nanoparticles; NMR; Nonlinear Optical Microscopy; Nuclear magnetic resonance; Nucleation; Ocean acidification; Organic chemistry; Proteins; Resonance; Spectroscopic analysis; Spectroscopy; Spectrum analysis
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.aam6371

Little is known about how stony corals build their calcareous skeletons. There are two prevailing hypotheses: that it is a physicochemically dominated process and that it is a biologically mediated one. Using a combination of ultrahigh-resolution three-dimensional imaging and two-dimensional solid-state nuclear magnetic resonance (NMR) spectroscopy, we show that mineral deposition is biologically driven. Randomly arranged, amorphous nanoparticles are initially deposited in microenvironments enriched in organic material; they then aggregate and form ordered aragonitic structures through crystal growth by particle attachment. Our NMR results are consistent with heterogeneous nucleation of the solid mineral phase driven by coral acid-rich proteins. Such a mechanism suggests that stony corals may be able to sustain calcification even under lower pH conditions that do not favor the inorganic precipitation of aragonite.