Volume 8 Issue 2
Evidence of a Biological Control over Origin, Growth and End of the Calcite Prisms in the Shells of Pinctada margaritifera (Pelecypod, Pterioidea)
Jean-Pierre Cuif, Manfred Burghammer, Virginie Chamard, Yannicke Dauphin, Pierre Godard, Gilles Le Moullac, Gernot Nehrke and Alberto Perez-Huerta
1Department of Earth Sciences, Paris-Sud University, Bt. 504, 91405 Orsay, France
2Department of Analytical Chemistry, Gent University, Krijgslaan 281 S12, 9000 Gent, Belgium
3Institut Fresnel UMR 7249, Aix-Marseille University, Centrale Marseille, 13013 Marseille, France
4Ecosystèmes insulaires océaniens UMR 241, Institut français de recherche pour l’exploitation de la mer (IFREMER) Centre du Pacifique, 98719 Taravao, Tahiti, French Polynesia
5Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany
6Department of Geological Sciences, The University of Alabama, 2018 Bevill Building, Tuscaloosa, AL 35487, USA
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Author to whom correspondence should be addressed.
Abstract
Consistently classified among the references for calcite simple prisms, the microstructural units that form the outer layer of the Pinctada margaritifera have been investigated through a series of morphological, crystallographical and biochemical characterizations. It is often said that the polygonal transverse shape of the prisms result from the competition for space between adjacent crystals. In contrast to this classical scheme the Pinctada prisms appear to be composed of four successive developmental stages from the concentrically growing disks on the internal side of the periostracum to the morphological, structural and compositional changes in both envelopes and mineral components at the end of the prisms. These latest structural and compositional changes predate nacre deposition, so that the end of prism growth is not caused by occurrence of nacre, but by metabolic changes in the secretory epithelium. This sequence makes obvious the permanent biological control exerted by the outer cell layer of the mantle in both organic envelopes and mineralizing organic phases.
Keywords:biomineralization; bivalve shell; microstructure; calcite prisms