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Structure and composition of Unio pictorum shell: arguments for the diversity of the nacroprismatic arrangement in molluscs

TitreStructure and composition of Unio pictorum shell: arguments for the diversity of the nacroprismatic arrangement in molluscs
Type de publicationJournal Article
Year of Publication2018
AuteursDauphin, Y, Luquet, G, Salomé, M, Bellot-Gurlet, L, Cuif, J-P
JournalJournal of Microscopy
Volume270
Ticket2
Pagination156-169
Date Published05/2018
Mots-clésbiomineralisation, composition, micro- and nanostructure, mollusc shells
Résumé

Mollusc shells are complex organomineral structures, the arrangement
and composition depending on the species. Most
studies are dedicated to shells composed of an aragonite nacreous
and a calcite prismatic layer, so the nacreous prismatic
model based on Pinctada and Atrina–Pinna. Here, we studied
the micro- and nanostructure, the mineralogy and composition
of a nacroprismatic bivalve species: Unio pictorum. The
prismatic layer of Unio is aragonite, and the inner structure
of the prismatic units strongly differs from those of the calcitic
layers. The shape of the prisms varies depending on their
growth stage. The first layers of nacre are similar to those of
gastropods (columnar nacre), then evolve towards the typical
bivalve arrangement (sheet nacre). Na, Sr, Mg, P and S are
present in both prisms and nacre. The organic prismatic envelopes
are rich in sulphur amino acids, whereas organic sulphate
is present within the prisms andthe nacreous tablets.Pis
present as phosphate, probably a mixture of organic andmineral
complex. Chemical distribution maps confirm the absence
of an organic membrane between the nacre and the prisms.
The comparison of the structure, mineralogy and composition
of Unio pictorum and different species show the diversity of
nacroprismatic shells, and that these features are taxonomically
dependent.

DOI10.1111/jmi.12669