title: Aragonite precipitation by "proto-polyps" in coral cell cultures.
abstract: The mechanisms of coral calcification at the molecular, cellular and tissue levels are poorly understood. In this study, we examine calcium carbonate precipitation using novel coral tissue cultures that aggregate to form "proto-polyps". Our goal is to establish an experimental system in which calcification is facilitated at the cellular level, while simultaneously allowing in vitro manipulations of the calcifying fluid. This novel coral culturing technique enables us to study the mechanisms of biomineralization and their implications for geochemical proxies. Viable cell cultures of the hermatypic, zooxanthellate coral, Stylophora pistillata, have been maintained for 6 to 8 weeks. Using an enriched seawater medium with aragonite saturation state similar to open ocean surface waters (Ω(arag)~4), the primary cell cultures assemble into "proto-polyps" which form an extracellular organic matrix (ECM) and precipitate aragonite crystals. These extracellular aragonite crystals, about 10 µm in length, are formed on the external face of the proto-polyps and are identified by their distinctive elongated crystallography and X-ray diffraction pattern. The precipitation of aragonite is independent of photosynthesis by the zooxanthellae, and does not occur in control experiments lacking coral cells or when the coral cells are poisoned with sodium azide. Our results demonstrate that proto-polyps, aggregated from primary coral tissue culture, function (from a biomineralization perspective) similarly to whole corals. This approach provides a novel tool for investigating the biophysical mechanism of calcification in these organisms.
authors.affiliation: Institute of Marine and Coastal Sciences, Rutgers, State University of New Jersey, New Brunswick, New Jersey, United States of America.
authors.forename: Tali
authors.initials: T
authors.lastname: Mass
authors.forename: Jeana L
authors.initials: JL
authors.lastname: Drake
authors.forename: Liti
authors.initials: L
authors.lastname: Haramaty
authors.forename: Yair
authors.initials: Y
authors.lastname: Rosenthal
authors.forename: Oscar M E
authors.initials: OM
authors.lastname: Schofield
authors.forename: Robert M
authors.initials: RM
authors.lastname: Sherrell
authors.forename: Paul G
authors.initials: PG
authors.lastname: Falkowski
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D002113:Calcification, Physiologic / Q000502:physiology*; D002119:Calcium Carbonate / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D008853:Microscopy; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D016133:Polymerase Chain Reaction; D061251:Primary Cell Culture
chemical_list: D002119:Calcium Carbonate