Search results for "Mollusca"

Taxonomic clarification of three taxa of Iberian geomitrids, Helix montserratensis Hidalgo, 1870 and subspecies (Gastropoda, Pulmonata), based on mor…

2017

Revisión taxonómica de tres taxones de geomítridos ibéricos, Helix montserratensis Hidalgo, 1870, y subespecies (Gastropoda, Pulmonata), basada en datos morfo–anatómicos Helix montserratensis (actualmente Xerocrassa montserratensis) es un geomítrido ibérico descrito por Hidalgo en 1870 en Montserrat (Barcelona, España). Sobre la base de varios caracteres conquiológicos, se describieron dos taxones muy similares, como variedades de este taxón: Helix montserratensis betulonensis y otro menos nombrado, Helix montserratensis delicatula. Estas variedades, sobre todo betulonensis, se han considerado subespecies de X. montserratensis, aunque algunos autores las consideran especies diferentes, basá…

The ‘Shellome’ of the Crocus Clam Tridacna crocea Emphasizes Essential Components of Mollusk Shell Biomineralization

2021

Molluscan shells are among the most fascinating research objects because of their diverse morphologies and textures. The formation of these delicate biomineralized structures is a matrix-mediated process. A question that arises is what are the essential components required to build these exoskeletons. In order to understand the molecular mechanisms of molluscan shell formation, it is crucial to identify organic macromolecules in different shells from diverse taxa. In the case of bivalves, however, taxon sampling in previous shell proteomics studies are focused predominantly on representatives of the class Pteriomorphia such as pearl oysters, edible oysters and mussels. In this study, we hav…

Inducible ASABF-Type Antimicrobial Peptide from the Sponge Suberites domuncula: Microbicidal and Hemolytic Activity in Vitro and Toxic Effect on Moll…

2011

Since sponges, as typical filter-feeders, are exposed to a high load of attacking prokaryotic and eukaryotic organisms, they are armed with a wide arsenal of antimicrobial/cytostatic low-molecular-weight, non-proteinaceous bioactive compounds. Here we present the first sponge agent belonging to the group of ASABF-type antimicrobial peptides. The ASABF gene was identified and cloned from the demospongeSuberites domuncula. The mature peptide, with a length of 64 aa residues has a predicted pI of 9.24, and comprises the characteristic CSαβ structural motif. Consequently, the S. domuncula ASABF shares high similarity with the nematode ASABFs ; it is distantly related to the defensins. The recom…

Structural and Dynamic Properties of the Homodimeric Hemoglobin from Scapharca inaequivalvis Thr-72→Ile Mutant: Molecular Dynamics Simulation, Low Te…

1998

AbstractMolecular dynamics simulations, low temperature visible absorption spectroscopy, and resonance Raman spectroscopy have been performed on a mutant of the Scapharca inaequivalvis homodimeric hemoglobin, where residue threonine 72, at the subunit interface, has been substituted by isoleucine. Molecular dynamics simulation indicates that in the Thr-72→Ile mutant several residues that have been shown to play a role in ligand binding fluctuate around orientations and distances similar to those observed in the x-ray structure of the CO derivative of the native hemoglobin, although the overall structure remains in the T state. Visible absorption spectroscopy data indicate that in the deoxy …

Monitoring programme on cadmium, lead and mercury in fish and seafood from Valencia, Spain: levels and estimated weekly intake.

2008

The study was carried out to determine the current levels of mercury, cadmium, and lead in fish and seafood from the market of Comunitat Valenciana, Spain. Levels of total mercury ranged from 0.02 to 3.15 mg kg⁻¹ w.w. (average = 0.073 mg kg⁻¹ w.w.). Cadmium concentrations ranged from 0.003 to 0.66 mg kg⁻¹ w.w. (average = 0.27 mg kg⁻¹ w.w.) for seafood, and between 0.003 and 0.71 mg kg⁻¹ w.w. (average = 0.01 mg kg⁻¹ w.w.) for marine fish. Concerning lead, concentrations from 0.02 to 0.36 mg kg⁻¹ w.w (average = 0.04 mg kg⁻¹ w.w.) were found in fish, and from 0.02 to 1.02 mg kg⁻¹ w.w. in seafood (average = 0.147 mg kg⁻¹ w.w.). The levels found were, in general, lower than maximum levels propos…

Cercarial Production of the Trematode Rhipidocotyle fennica in Clams Kept in the Field

1998

The numbers of cercariae that trematodes produce have been previously investigated in the laboratory but not in the field. I studied cercarial production of the bucephalid trematode Rhipidocotyle fennica in the freshwater unionid clam Anodonta piscinalis kept under natural conditions. Naturally infected clams (n = 180) were collected and marked in early June 1996. Every 14 days, starting from the collection date and ending in October, these clams were taken to the laboratory where they were monitored for the emergence of trematode cercariae. Between monitoring dates, the clams were returned to the collection site. From a random subsample of infected clams (n = 12), the number of cercariae p…

Burrowing behaviour affects Paraergasilus rylovi abundance in Anodonta piscinalis.

2006

Burrowing depth may affect predation rate, feeding ability and reproduction in bivalve clams. We studied the effect of burrowing depth on the abundance of the ergasilid Paraergasilus rylovi in the freshwater bivalve clam Anodonta piscinalis. We transplanted uninfected clams to a lake where they were allowed to choose their preferred burrowing depth, and were exposed naturally to copepodids of the parasite. There was a significant positive correlation between proportionate burrowing depth (PBD) and the abundance of P. rylovi at the end of the 17-day experiment, the deeper-burrowed clams harbouring more P. rylovi. Original PBD (0%, 50%, 100%) did not influence the final PBD or parasite abunda…

Investigation of Li/Ca variations in aragonitic shells of the ocean quahogArctica islandica, northeast Iceland

2009

Interannual and intra-annual variations in lithium-to-calcium ratio were investigated with high temporal resolution in the aragonitic outer shell layer of juvenile Arctica islandica (Mollusca; Bivalvia) collected alive in 2006 off northeast Iceland. Li/Ca shell ranged between 7.00 and 11.12 µmol mol -1 and presented well-marked seasonal cycles with minimum values recorded at the annual growth lines; a general pattern was a progressive increase in Li/Ca shell from March to May, followed by a plateau in June and a decrease down to minimum values in July-August. Li/Ca shell was correlated with d 18 O shell -derived temperature, but the strength of this relationship was weak ( r 2 p shell in A.…

Evolution of molluscan hemocyanins as deduced from DNA sequencing

2004

Variability of shell repair in the Manila clam Ruditapes philippinarum affected by the Brown Ring Disease: A microstructural and biochemical study

2011

11 pages; International audience; For more than two decades, the Manila clam Ruditapes philippinarum has been regularly affected by Brown Ring Disease (BRD), an epizootic event caused by the bacterium Vibrio tapetis and characterized by the development of a brown deposit on the inner face of valves. Although BRD infection is often lethal, some clams recover by mineralizing a new repair shell layer, which covers the brown deposit and fully isolates it from living tissues. In order to understand this specific shell repair process, the microstructures of repaired zones were compared to those of shells unaffected by BRD. In addition, the organic matrix associated with unaffected shells and to r…