title: Study of the crystallographic architecture of corals at the nanoscale by scanning transmission X-ray microscopy and transmission electron microscopy.
abstract: We have investigated the nanotexture and crystallographic orientation of aragonite in a coral skeleton using synchrotron-based scanning transmission X-ray microscopy (STXM) and transmission electron microscopy (TEM). Polarization-dependent STXM imaging at 40-nm spatial resolution was used to obtain an orientation map of the c-axis of aragonite on a focused ion beam milled ultrathin section of a Porites coral. This imaging showed that one of the basic units of coral skeletons, referred to as the center of calcification (COC), consists of a cluster of 100-nm aragonite globules crystallographically aligned over several micrometers with a fan-like distribution and with the properties of single crystals at the mesoscale. The remainder of the skeleton consists of aragonite single-crystal fibers in crystallographic continuity with the nanoglobules comprising the COC. Our observation provides information on the nm-scale processes that led to biomineral formation in this sample. Importantly, the present study illustrates how the methodology described here, which combines HRTEM and polarization-dependent synchrotron-based STXM imaging, offers an interesting new approach for investigating biomineralizing systems at the nm-scale.
authors.affiliation: Institut de Minéralogie et de Physique des Milieux Condensés, UMR 7590, CNRS, Universités Paris 6 & IPGP. 4 Place Jussieu, 75005 Paris, France. karim.benzerara@impmc.jussieu.fr
authors.forename: Karim
authors.initials: K
authors.lastname: Benzerara
authors.forename: Nicolas
authors.initials: N
authors.lastname: Menguy
authors.forename: Martin
authors.initials: M
authors.lastname: Obst
authors.forename: Jarosław
authors.initials: J
authors.lastname: Stolarski
authors.forename: Maciej
authors.initials: M
authors.lastname: Mazur
authors.forename: Tolek
authors.initials: T
authors.lastname: Tylisczak
authors.forename: Gordon E
authors.initials: GE
authors.lastname: Brown
authors.forename: Anders
authors.initials: A
authors.lastname: Meibom
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000737:chemistry* / Q000648:ultrastructure*; D002119:Calcium Carbonate / Q000737:chemistry; D003461:Crystallography / Q000379:methods*; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D017348:Microscopy, Electron, Scanning Transmission / Q000379:methods; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008903:Minerals / Q000737:chemistry; D036103:Nanotechnology; D014965:X-Rays
chemical_list: D008903:Minerals; D002119:Calcium Carbonate