Search results for "Shells"
showing 10 items of 66 documents
The shell of the invasive bivalve species Dreissena polymorpha: biochemical, elemental and textural Investigations.
2016
28 pages; International audience; The zebra mussel Dreissena polymorpha is a well-established invasive model organism. Although extensively used in environmental sciences, virtually nothing is known of the molecular process of its shell calcification. By describing the microstructure, geochemistry and biochemistry/proteomics of the shell, the present study aims at promoting this species as a model organism in biomineralization studies, in order to establish a bridge with ecotoxicology, while sketching evolutionary conclusions. The shell of D. polymorpha exhibits the classical crossed-lamellar/complex crossed lamellar combination found in several heterodont bivalves, in addition to an extern…
A Multilayered Plate Theory with Transverse Shear and Normal Warping Functions
2016
A multilayered plate theory which takes into account transverse shear and normal stretching is presented. The theory is based on a seven-unknowns kinematic field with five warping functions. Four warping functions are related to the transverse shear behaviour, the fifth is related to the normal stretching. The warping functions are issued from exact three-dimensional solutions. They are related to the variations of transverse shear and normal stresses computed at specific points for a simply supported bending problem. Reddy, Cho-Parmerter and (a modified version of) Beakou-Touratier theories have been retained for comparisons. Extended versions of these theories, able to manage the normal s…
Our Friend and Mathematician Karl Strambach
2020
This paper is dedicated to Karl Strambach on the occasion of his 80th birthday. Here we want to describe our work with Prof. Karl Strambach.
Evolution and biomineralization of pteropod shells
2021
12 pages; International audience; Shelled pteropods, known as sea butterflies, are a group of small gastropods that spend their entire lives swimming and drifting in the open ocean. They build thin shells of aragonite, a metastable polymorph of calcium carbonate. Pteropod shells have been shown to experience dissolution and reduced thickness with a decrease in pH and therefore represent valuable bioindicators to monitor the impacts of ocean acidification. Over the past decades, several studies have highlighted the striking diversity of shell microstructures in pteropods, with exceptional mechanical properties, but their evolution and future in acidified waters remains uncertain. Here, we re…
Temperature-induced microstructural changes in shells of laboratory-grown Arctica islandica (Bivalvia).
2021
Bivalve shells are increasingly used as archives for high-resolution paleoclimate analyses. However, there is still an urgent need for quantitative temperature proxies that work without knowledge of the water chemistry–as is required for δ18O-based paleothermometry–and can better withstand diagenetic overprint. Recently, microstructural properties have been identified as a potential candidate fulfilling these requirements. So far, only few different microstructure categories (nacreous, prismatic and crossed-lamellar) of some short-lived species have been studied in detail, and in all such studies, the size and/or shape of individual biomineral units was found to increase with water temperat…
Climate variation during the Holocene influenced the skeletal properties of Chamelea gallina shells in the North Adriatic Sea (Italy)
2021
Understanding how marine taxa will respond to near-future climate changes is one of the main challenges for management of coastal ecosystem services. Ecological studies that investigate relationships between the environment and shell properties of commercially important marine species are commonly restricted to latitudinal gradients or small-scale laboratory experiments. This paper aimed to explore the variations in shell features and growth of the edible bivalve Chamelea gallina from the Holocene sedimentary succession to present-day thanatocoenosis of the Po Plain-Adriatic Sea system (Italy). Comparing the Holocene sub-fossil record to modern thanatocoenoses allowed obtaining an insight o…
The shell organic matrix of the crossed lamellar queen conch shell (Strombus gigas)
2014
10 pages; International audience; In molluscs, the shell organic matrix comprises a large set of biomineral-occluded proteins, glycoproteins and polysaccharides that are secreted by the calcifying mantle epithelium, and are supposed to display several functions related to the synthesis of the shell. In the present paper, we have characterized biochemically the shell matrix associated to the crossed-lamellar structure of the giant queen conch Strombus gigas. The acid-soluble (ASM) and acid-insoluble (AIM) matrices represent an extremely minor fraction of the shell. Both are constituted of polydisperse and of few discrete proteins among which three fractions, obtained by preparative SDS-PAGE …
The shell matrix of the european thorny oyster, Spondylus gaederopus: microstructural and molecular characterization.
2020
17 pages; International audience; Molluscs, the largest marine phylum, display extraordinary shell diversity and sophisticated biomineral architectures. However, mineral-associated biomolecules involved in biomineralization are still poorly characterised.We report the first comprehensive structural and biomolecular study of Spondylus gaederopus, a pectinoid bivalve with a peculiar shell texture. Used since prehistoric times, this is the best-known shell of Europe’s cultural heritage. We find that Spondylus microstructure is very poor in mineral-bound organics, which are mostly intercrystalline and concentrated at the interface between structural layers.Using high-resolution liquid chromatog…
Shell proteome of rhynchonelliform brachiopods.
2015
7 pages; International audience; Brachiopods are a phylum of marine invertebrates that have an external bivalved shell to protect their living tissues. With few exceptions, this biomineralized structure is composed of calcite, mixed together with a minor organic fraction, comprising secreted proteins that become occluded in the shell structure, once formed. This organic matrix is thought to display several functions, in particular, to control mineral deposition and to regulate crystallite shapes. Thus, identifying the primary structure of matrix proteins is a prerequisite for generating bioinspired materials with tailored properties. In this study, we employed a proteomic approach to identi…
Multi-isotopic and trace element evidence against different formation pathways for oyster microstructures
2021
Geochimica et cosmochimica acta 308, 326-352 (2021). doi:10.1016/j.gca.2021.06.012