Search results for "Oyster"

Climatic fluctuations and seasonality during the Late Jurassic (Oxfordian–Early Kimmeridgian) inferred from delta18O of Paris Basin oyster shells.

2008

10 pages; International audience; Oxygen isotope data from biostratigraphically well-dated oyster shells from the Late Jurassic of the eastern Paris Basin are used to reconstruct the thermal evolution of western Tethyan surface waters during the Early Oxfordian–Early Kimmeridgian interval. Seventy eight oyster shells were carefully screened for potential diagenetic alteration using cathodoluminescence microscopy. Isotope analyses were performed on nonluminescent parts of shells (n=264). Intra-shell δ18O variability was estimated by microsampling along a transect perpendicular to the growth lines of the largest oyster shell. The sinusoidal distribution of the δ18O values along this transect …

Pearl grafting: tracking the biological origin of nuclei by straightforward immunological methods.

2018

9 pages; International audience; French Polynesia is renowned for the production of Tahitian black pearl. These gems are obtained by grafting a nucleus into the gonad of a receiving oyster together with a graft, i.e. a small section of mantle tissue of a donor oyster. This procedure initiates the formation of a pearl sack around the nucleus, and subsequently, the deposition of concentric layers of nacre. The nucleus plays a key-role in pearl formation and its characteristics influence markedly the quality of the final product. As it is manufactured from mollusc shells, it contains a small percentage of organics. In the present paper, we used a set of biochemical techniques to characterize a…

Forty questions of importance to the policy and practice of native oyster reef restoration in Europe

2020

© 2020 The Authors. Aquatic Conservation: Marine and Freshwater Ecosystems published by John Wiley & Sons Ltd Oyster reefs are among the most threatened marine habitats globally. In Europe, oyster reefs have been extirpated from most locations within their historical range. Active restoration of the native oyster (Ostrea edulis) in Europe has grown substantially in recent years. In sharing experiences between oyster restoration projects in Europe at the Native Oyster Restoration Alliance conference, NORA2, in Edinburgh in May 2019, it became apparent that a number of similar barriers are experienced. This study identified the top 40 questions, which, if answered, would have the greatest inf…

Shell repair process in the green ormer Haliotis tuberculata: a histological and microstructural study.

2008

In the present paper, juvenile and adult shells of the green ormer Haliotis tuberculata ('Oreille de Saint-Pierre') were perforated in a zone close to the shell edge and the shell repair process was followed at two levels: (1) by observing the histology of the calcifying mantle in the repair zone and (2) by analyzing with SEM the microstructure of the shell repair zone. Histological data clearly show the presence of calcium carbonate granules into the connective tissues, but not in the epithelial cells. This suggests that calcium carbonate granules are synthesized by sub-epithelial cells and actively transported through the epithelium to the repair zone, via a process which may be similar t…

Pleurotus opuntiae revisited e An insight to the phylogeny of dimitic Pleurotus species with emphasis on the P. djamor complex

2018

Abstract The name Pleurotus opuntiae is indiscriminately used for describing mushrooms with white to off-white to white-grey pilei with short or absent stipe and dimitic hyphal system, which grow on plants of the genera Opuntia, Yucca, Agave, Phytolacca etc. However, the outcome of the present study evidences that this name should be reserved for specimens deriving from the Mediterranean area only; an epitype originating from Italy on Opuntia ficus-indica is designated. Pertinent material was sequenced by using the internal transcribed spacer region (ITS) and found to be phylogenetically related to P. djamor from Kenya and Nigeria, while members of the P. djamor complex from other continent…

Experimental and natural cathodoluminescence in the shell of Crassostrea gigas from Thau lagoon (France): ecological and environmental implications.

2006

We present a cathodoluminescence (CL) study of growth layer deposition in the shell of the oyster Crassostrea gigas. CL is based on the physical properties of lattice-bound manganese (Mn2+), which is the main activator in calcium carbonate. Our study involved chemical marking by immersing individuals in seawater to which manganese chloride had been added, and subsequent reading of the shell with CL microscopy coupled with numeric treatment of microphotographs; CL emission was analyzed using a scanning electron microscope coupled to a spectrometer. Since the marking did not harm the oysters, repeated markings were possible, allowing validation of the inferences made from analysis of the shel…

The importance of thermal history: costs and benefits of heat exposure in a tropical, rocky shore oyster.

2015

Although thermal performance is widely recognized to be pivotal in determining species' distributions, assessment of this performance is often based on laboratory acclimated individuals, neglecting their proximate thermal history. The thermal history of a species sums the evolutionary history and, importantly, the thermal events recently experienced by individuals, including short-term acclimation to environmental variations. Thermal history is perhaps of greatest importance for species inhabiting thermally challenging environments and therefore assumed to be living close to their thermal limits, such as in the tropics. To test the importance of thermal history the responses of the tropical…

2017

The consequences of emerging marine diseases on the evolutionary trajectories of affected host populations in the marine realm are largely unexplored. Evolution in response to natural selection depends on the genetic variation of the traits under selection and the interaction of these traits with the environment (GxE). However, in the case of diseases, genotypes of pathogens add another dimension to this interaction. Therefore, the study of disease resistance needs to be extended to the interaction of host genotype, pathogen genotype and environment (GxGxE). In the present study we used a full-sib breeding design crossing two genetically differentiated populations of the Pacific oyster Cras…

Thermal stability of nacre proteins of the polynesian pearl oyster: a proteomic study.

2015

Mollusc shells are organic-inorganic composites that are often preserved in the fossil record. However, the way the organic fraction, also called shell matrix, gets fossilized remains an unsolved question, in spite of several old and more recent studies. In the present paper, we have tried to mimic a diagenetic process by constantly heating for ten days at 100°C fresh nacre powder samples of the Polynesian pearl oyster Pinctadamargaritifera. Each day, aliquots of nacre powder were sampled and the matrix was subsequently extracted. It was further analysed by direct weigh quantification, by immunological techniques and by proteomics. Our preliminary data suggest that nacre proteins, when heat…

Optimization of PMAxx pretreatment to distinguish between human norovirus with intact and altered capsids in shellfish and sewage samples

2018

Shellfish contamination by human noroviruses (HuNoVs) is a serious health and economic problem. Recently an ISO procedure based on RT-qPCR for the quantitative detection of HuNoVs in shellfish has been issued, but these procedures cannot discriminate between inactivated and potentially infectious viruses. The aim of the present study was to optimize a pretreatment using PMAxx to better discriminate between intact and heat-treated HuNoVs in shellfish and sewage. To this end, the optimal conditions (30 min incubation with 100 μM of PMAxx and 0.5% of Triton, and double photoactivation) were applied to mussels, oysters and cockles artificially inoculated with thermally-inactivated (99 °C for 5 …