Search results for " bivalvi"

I limiti della nicchia fondamentale e le temperature di Arrhenius dei bivalvi Brachidontes pharaonis e Mytilaster minimus

2012

Anisotropic lattice distortions in biogenic calcite induced by intra-crystalline organic molecules.

2006

9 pages; International audience; We have performed precise structural measurements on five different calcitic seashells by high-resolution X-ray powder diffraction on a synchrotron beam line and by laboratory single crystal X-ray diffraction. The unit cell parameters a and c of biogenic calcite were found to be systematically larger than those measured in the non-biogenic calcite. The maximum lattice distortion (about 2.10(-3)) was detected along the c-axis. Under heat treatment above 200 degrees C, a pronounced lattice relaxation was observed, which allowed us to conclude that anisotropic lattice swelling in biogenic calcite is induced by organic macromolecules incorporated within the sing…

The degradation of intracrystalline mollusc shell proteins: a proteomics study of Spondylus gaederopus.

2021

Mollusc shells represent excellent systems for the preservation and retrieval of genuine biomolecules from archaeological or palaeontological samples. As a consequence, the post-mortem breakdown of intracrystalline mollusc shell proteins has been extensively investigated, particularly with regard to its potential use as a "molecular clock" for geochronological applications. But despite seventy years of ancient protein research, the fundamental aspects of diagenesis-induced changes to protein structures and sequences remain elusive. In this study we investigate the degradation of intracrystalline proteins by performing artificial degradation experiments on the shell of the thorny oyster, Spo…

Caspartin and calprismin, two proteins of the shell calcitic prisms of the Mediterranean fan mussel Pinna nobilis.

2005

We used the combination of preparative electrophoresis and immunological detection to isolate two new proteins from the shell calcitic prisms of Pinna nobilis, the Mediterranean fan mussel. The amino acid composition of these proteins was determined. Both proteins are soluble, intracrystalline, and acidic. The 38-kDa protein is glycosylated; the 17-kDa one is not. Ala, Asx, Thr, and Pro represent the dominant residues of the 38-kDa protein, named calprismin. An N-terminal sequence was obtained from calprismin. This sequence, which comprises a pattern of 4 cysteine residues, is not related to any known protein. The second protein, named caspartin, exhibits an unusual amino acid composition, …

Modelli meccanicistici biofisici e bioenergetici DEB per la predizione della nicchia ecologica dei sospensivori bentonici in Mediterraneo in un conte…

2014

I modelli meccanicistici basati sull’analisi dei tratti funzionali comportamentali (e.g. preferenze alimentari), fisiologici (e.g. vulnerabilità alla temperatura) e morfologici (e.g. forma e colore) che concorrono nell’ottimizzazione dell’incoming energetico del singolo organismo sono una soluzione pratica per fornire previsioni accurate sull’abbondanza degli organismi di una specie in un mondo in continuo cambiamento (Araujo & Rahbek 2006). Tale approccio è definito come ecomeccanica e ha rappresentato la base sulla quale costruire questo progetto di tesi. L’integrazione dei più recenti modelli biofisici e bioenergetici ha permesso di evidenziare tanto le strategie di gestione ed allocazio…

The effect of lowered pH on shelled organisms of shallow waters: the case of Brachidontes pharaonis (Mollusca, Bivalvia).

2010

The shell matrix of the freshwater mussel Unio pictorum (Paleoheterodonta, Unionoida). Involvement of acidic polysaccharides from glycoproteins in na…

2007

13 pages; International audience; Among molluscs, the shell biomineralization process is controlled by a set of extracellular macromolecular components secreted by the calcifying mantle. In spite of several studies, these components are mainly known in bivalves from only few members of pteriomorph groups. In the present case, we investigated the biochemical properties of the aragonitic shell of the freshwater bivalve Unio pictorum (Paleoheterodonta, Unionoida). Analysis of the amino acid composition reveals a high amount of glycine, aspartate and alanine in the acid-soluble extract, whereas the acid-insoluble one is rich in alanine and glycine. Monosaccharidic analysis indicates that the in…

Caratterizzazione molecolare di norovirus GIV ed altri virus enterici in molluschi bivalvi : uno studio preliminare

2011

I virus enterici si replicano nell’intestino umano e possono essere eliminati dagli individui infetti ad elevate concentrazioni; pertanto i reflui urbani possono trasportare una grande quantità di patogeni responsabili di infezioni oro-fecali e contaminare le acque superficiali, incluse quelle marine. I molluschi bivalvi eduli sono spesso implicati nella trasmissione di malattie gastroenteriche di origine virale in quanto, essendo organismi filtratori, rappresentano un potenziale serbatoio di agenti patogeni e sostanze tossiche. Nonostante i miglioramenti delle tecniche per il trattamento delle acque reflue e la classificazione delle aree di allevamento e raccolta dei molluschi, il rischio …