Consulta: creatorFacets:"Delbarre Ladrat, Christine"
Registros recuperados: 19
Data/hora: 01/06/2024 02:34:47

Characterization of biofilm extracts from two marine bacteria
Provedor de dados: 5
Autores: Passerini, Delphine; Fecamp, Florian; Marchand, Laetitia; Kolypczuk, Laetitia; Bonnetot, Sandrine; Sinquin, Corinne; Verrez-bagnis, Veronique; Hervio Heath, Dominique; Colliec Jouault, Sylvia; Delbarre Ladrat, Christine.
In the marine environment, biofilm formation is an important lifestyle for microorganisms. A biofilm is comprised of cells embedded in an extracellular matrix that holds them close together and keeps the biofilm attached to the colonized surface. This predominant lifestyle and its main regulation pathway, namely quorum-sensing (QS), have been shown to induce specific bioactive metabolites. In this study, we investigated the biofilm formation by two marine bacteria belonging to the Vibrio species to discover potentially innovative bioactive compounds. We proposed a protocol to isolate biofilm extracts, to analyze their biochemical composition, and to compare them to planktonic cell extracts. Cells were grown attached to a plastic surface; extracts were...
Tipo: Text
Palavras-chave: Vibrio; Biofilm; Polysaccharide; Quorum-sensing; Activity.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00592/70381/68461.pdf

Assessment of biochemical methods to detect enzymatic depolymerization of polysaccharides
Provedor de dados: 5
Autores: Rigouin, Coraline; Delbarre Ladrat, Christine; Sinquin, Corinne; Colliec-jouault, Sylvia; Dion, M.
To find biocatalyst allowing depolymerization of new polysaccharides, one needs to get a sensitive and well adapted method to a screening program. This led us to compare biochemical methods of detection of the depolymerization. Currently used methods such as reducing sugars assays, double bond monitoring or molecular weight determination were tested to follow the kinetic of depolymerization with different enzyme / polysaccharide couples. The range of concentrations of assorted enzymes allowed us to identify the most sensitive and appropriate method to detect polysaccharide degradation. Reducing sugars assays are quantitative, sensitive and almost usable with all kind of polysaccharide but some compounds may interfere with them. When polysaccharide is...
Tipo: Text
Palavras-chave: Detection; Enzyme; Depolymerization; Carbohydrate.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2008/publication-4723.pdf

Calpain and cathepsin activities in post mortem fish and meat muscles
Provedor de dados: 5
Autores: Cheret, Romuald; Delbarre Ladrat, Christine; De Lamballerie Anton, Marie; Verrez-bagnis, Veronique.
Post mortem tenderization is one of the most unfavourable quality changes in fish muscle and this contrasts with muscle of mammalian meats. The tenderization can be partly attributed to the acid lysosomal cathepsins and cytosolic neutral calcium-activated calpains. In this study, these proteases from fish and bovine muscles were quantified and compared. The cathepsin B and L activities were in more important amounts in sea bass white muscle than in bovine muscle. On the other hand, cathepsin D activity was 1.4 times higher in meat that in fish muscle, while cathepsin H was negligible in both muscles. Calpain activities were similar in both types of muscle. Moreover, calpastatin (calpain endogenous inhibitor) level is 3.9 times higher in sea bass white...
Tipo: Text
Palavras-chave: Meat; Fish; Protease; Cathepsin; Calpain.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-3646.pdf

Mining of the biosynthetic mechanisms of Vibrio spp. polysaccharides and potential role in biofilm formation
Provedor de dados: 5
Autores: Verrez-bagnis, Veronique; Soree, Marion; Passerini, Delphine; Kolypczuk, Laetitia; Marchand, Laetitia; Bonnetot, Sandrine; Fecamp, Florian; Lozach, Solen; Hervio Heath, Dominique; Delbarre Ladrat, Christine.
Vibrio spp. are ubiquitous marine bacteria that are ecologically and metabolically diverse members of planktonic and animal associated microbial communities. They encompass the ancient and well-studied human pathogen, Vibrio cholerae, and two other human pathogens, V. vulnificus and V. parahaemolyticus, as well as some less thoroughly characterized animal pathogens. Virulence is based on a wide diversity of mechanisms involved in motility and host colonization, in ability to persist and develop, and in damage generation. Polysaccharides may play major roles in virulence and are major components of extracellular polymeric matrix synthesized upon biofilm growth. They may also exhibit biological features, especially those similar to animal-derived...
Tipo: Text
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00514/62605/66965.pdf

Effects of high pressure on texture and microstructure of sea bass (Dicentrarchus labrax L.) fillets
Provedor de dados: 5
Autores: Cheret, Romuald; Chapleau, Nicolas; Delbarre Ladrat, Christine; Verrez-bagnis, Veronique; De Lamballerie, Marie.
High pressure is an innovative non-thermal food-preservation technology. We studied the effect of high-pressure treatment up-to 500 MPa for 5 min on physical characteristics of sea bass fillets after 0, 7, and 14 d of refrigerated storage.. Color results exhibited an increase of lightness and a slight change of hue, which might be imperceptible in cooked fish. High-pressure treatment induced a decrease of exudation and water-holding capacity Pressure treatment above 300 MPa provoked higher fish hardness after storage than in untreated sample, proving the ability of high pressure to improve textural, quality of chilled, stored fish fillet. These assessments were corroborated with microstructure observations. We showed that high-pressure treatment at 500 MPa...
Tipo: Text
Palavras-chave: Preservation; Microstructure; Texture profile analysis; High pressure; Fish.
Ano: 2005
URL: http://archimer.ifremer.fr/doc/2005/publication-734.pdf

Adhésion et substances polymériques extracellulaires d’une nouvelle espèce bactérienne marine
Provedor de dados: 5
Autores: Leroy, Celine; Compere, Chantal; Delbarre Ladrat, Christine; Raguenes, Gerard; Ghillebaert, François; Combes, Didier.
Une nouvelle bactérie marine du genre Pseudoalteromonas sp., D41, formant rapidement des biofilms sur tout type de matériau (verre, acier inoxydable, Téflon) a été isolée en Baie de Brest. L’objectif de ce présent travail est de caractériser et décrire cette bactérie capable de produire des exopolymères constitués en majorité de protéines. Le rôle des protéines sécrétées, dans les mécanismes d’adhésion, est discuté.
Tipo: Text
Ano: 2005
URL: http://archimer.ifremer.fr/doc/00088/19950/17617.pdf

Proteolytic potential in white muscle of sea bass (Dicentrarchus labrax L.) during post mortem storage on ice: time-dependent changes in the activity of the components of the calpain system
Provedor de dados: 5
Autores: Delbarre Ladrat, Christine; Verrez-bagnis, Veronique; Noel, Joelle; Fleurence, Joel.
The variations in the amounts of milli-calpain and its specific inhibitor in the white muscle of sea bass (Dicentrarchus labrax) during storage at 4 degreesC for up to 7 days were determined after separation by hydrophobic chromatography on a Phenyl Sepharose vel. There was a significant decline in post-slaughter m-calpain activity with an important inter-individual variability in the rate of decrease of the total activity. In contrast with the calpastatin of mammalian post mortem muscles, calpastatin remained constant within fish muscles after death. The initial levels of protease and inhibitor activities, and their behaviour through post mortem storage. are discussed and implications for the mechanism of tenderisation of fish muscle are suggested. (C)...
Tipo: Text
Palavras-chave: Proteolysis; Post mortem; Fish muscle; Calpain; Calpastatin; Neutral calcium dependent protease.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-1683.pdf

Proteins and proteolytic activity changes during refrigerated storage in sea bass (Dicentrarchus labrax L.) muscle after high-pressure treatment
Provedor de dados: 5
Autores: Cheret, Romuald; Hernandez Andres, Aránzazu; Delbarre Ladrat, Christine; De Lamballerie, Marie; Verrez-bagnis, Veronique.
Contrary to other preservation methods like thermal treatments, high pressure can destroy microorganisms without affecting the nutritional quality, color, or food texture. The firm texture of fish flesh is an important quality parameter. During the refrigerated storage, the tissue becomes softer and the muscle is deteriorated by different proteases. The aim of this study was to study the modification of the fish muscle proteins after high-pressure treatment during the refrigerated storage and to evaluate the effect of high-pressure treatment level on the post-mortem protein changes and enzyme activities. The calpain activity decreased with the high-pressure treatment and evolved differently during the refrigerated storage, depending on the level of...
Tipo: Text
Palavras-chave: Cathepsins; Calpains; Sarcoplasmic proteins; Myofibrillar proteins; Post mortem denaturation; High pressure; Fish.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1708.pdf

Effects of commercial enzymes on the adhesion of a marine biofilm-forming bacterium
Provedor de dados: 5
Autores: Leroy, C.; Delbarre Ladrat, Christine; Ghillebaert, F.; Compere, Chantal; Combes, D.
The antifouling potential of commercial hydrolases, four proteases, seven glycosidases and one lipase was evaluated on the adhesion of marine Pseudoalteromonas sp. D41. The experimental method, adapted to screen antifouling agents, was based on bacterial adhesion in natural sterile sea water in a microtiter plate and on total biomass quantification by the fluorescent dye DAPI (4[prime]6-diamidino-2-phenylindole). Savinase (subtilisin) was the most effective hydrolase in both the prevention of bacterial adhesion and the removal of adhered bacteria. However, some enzymatic preparations tested such as Amano protease were not only ineffective but also increased the number of adhered bacterial cells. Enumeration using epifluorescence microscopy of CTC...
Tipo: Text
Palavras-chave: Marine biofilm; Antifouling; Pseudoalteromonas; Enzymes; Adhesion.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-6140.pdf

Relative contribution of calpain and cathepsins to protein degradation in muscle of sea bass (Dicentrarchus labrax L.)
Provedor de dados: 5
Autores: Delbarre Ladrat, Christine; Verrez-bagnis, Veronique; Noel, Joelle; Fleurence, Joel.
The effects of a milli(m)-calpain isolated from the white muscle of sea bass (Dicentrarchus labrax L) and commercial cathepsins B, D and L, used in combination on the myofibrillar and sarcoplasmic proteins were examined. Protein digestion was first performed by the endogenous m-calpain, (luring 2 h before the addition of a mixture of cathepsins B, D and L and a further incubation up to 22 h. Calpain degraded a 27 kDa sarcoplasmic component as well as myosin heavy chain, a-actinin, desmin and a 32 kDa component from the myofibrillar fraction. A 97 kDa component and the assumed creatine kinase-aldolase doublet were degraded during the incubation of sarcoplasmic proteins with the cathepsin mixture while, among the myofibrillar proteins, myosin, actin,...
Tipo: Text
Palavras-chave: Postmortem aging; Fish muscle; Proteolysis; Cathepsins; Neutral calcium dependent protease.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-1682.pdf

In vitro proteolysis of myofibrillar and sarcoplasmic proteins of white muscle of sea bass (Dicentrarchus labrax L.): effects of cathepsins B, D and L
Provedor de dados: 5
Autores: Delbarre Ladrat, Christine; Verrez-bagnis, Veronique; Noel, Joelle; Fleurence, Joel.
The purpose of this study was to obtain additional information regarding proteolysis mechanisms and disorganization of fish myofibrils resulting in a loss of flesh quality. The ability of cathepsins to degrade in vitro myofibrillar and sarcoplasmic proteins from fish muscle was investigated in order to explain their role in post mortem softening. This led to the identification of substrates of the enzymes. Cathepsins degraded myosin heavy chain and a-actinin. Tropomyosin and actin were only susceptible to the action of cathepsin L. Troponin T (assumed 32 kDa component) was resistant only to the action of cathepsin D. Desmin was degraded by cathepsins B and L. Slight changes of some other myofibrillar or cytosolic proteins were also observed (creatine...
Tipo: Text
Palavras-chave: Post mortem degradation; Fish muscle proteins; Cathepsins; In vitro proteolysis.
Ano: 2003
URL: http://archimer.ifremer.fr/doc/2003/publication-1684.pdf

Effect of high pressure on the calpain-calpastatin system in fish muscle
Provedor de dados: 5
Autores: Cheret, Romuald; Delbarre Ladrat, Christine; Verrez-bagnis, Veronique; De Lamballerie, Marie.
Calpains (calcium-activated neutral proteases) of sea bass (Dicentrarchus labrax L.) muscle may participate in the degradation of muscle tissue during postmortem storage. These enzymes are regulated by calpastatin, their endogenous specific inhibitor. The objective of this study was to evaluate the changes encountered by the calpain system during the postmortem storage of fish muscle after high-pressure treatment. From 100 MPa, high-pressure treatment of purified calpains results in a loss of their activity as well as in the dissociation of the heterodimeric form. In muscle, the high-pressure processing decreases the initial activity of calpain. This loss in activity may be due to an inactivation by a change of structure. Initial calpastatin activity is...
Tipo: Text
Palavras-chave: Postmortem denaturation; High pressure; Fish; Calpain system.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2786.pdf

In vitro proteolysis of myofibrillar and sarcoplasmic proteins of European sea bass (Dicentrarchus Labrax L) by an endogenous m-calpain
Provedor de dados: 5
Autores: Verrez-bagnis, Veronique; Delbarre Ladrat, Christine; Noel, Joelle; Fleurence, Joel.
The effects of m-calpain isolated from the skeletal muscle of sea bass on sarcoplasmic and myofibrillar proteins isolated from the same tissue were examined in vitro. Incubation of sarcoplasmic proteins with m-calpain resulted in only a slight decrease (0.7 kDa) in the molecular weight (MW) of a 26.5 kDa protein. Degradation of myofibrils, monitored by quantification of TCA-soluble peptides generated, resulted in the maximum amount of peptides being generated after 1 h of incubation at 25degreesC. Noticeable modifications in the SDS-PAGE profile of digested myofibrils were observed, including partial denaturation of myosin heavy chain and the release of tropomyosin, similar to69 and similar to27 kDa doublet bands and a few polypeptides of MW lower than 20...
Tipo: Text
Palavras-chave: Dicentrarchus labrax L; Proteolysis; Sarcoplasmic protein; Calpain; Myofibrillar protein.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/2002/publication-1108.pdf

A biofilm-forming marine bacterium producing proteins as extracellular polymeric substances
Provedor de dados: 5
Autores: Leroy, Celine; Delbarre Ladrat, Christine; Ghillebaert, François; Compere, Chantal; Combes, Didier.
EPS biochemical characterization and observation by epifluorescencemicroscopy. Development of a marine biofilmformation model onto a polystyrene microtiterplate using the “O’Tooleand Koltermethod”[1] adapted with the well known fluorescent DNA staining DAPI
Tipo: Text
Ano: 2005
URL: http://archimer.ifremer.fr/doc/00089/19998/17661.pdf

Trends in postmortem aging in fish: Understanding of proteolysis and disorganization of the myofibrillar structure
Provedor de dados: 5
Autores: Delbarre Ladrat, Christine; Cheret, Romuald; Taylor, Romuald; Verrez-bagnis, Veronique.
Introduction :  Quality attributes of fish flesh, including food safety, organoleptic features, nutritional quality and aptitude to industrial transformation, influence consumption and acceptability of fish as food. Fish sensorial changes and texture properties are closely linked to freshness. Along with ante mortem muscle biochemistry, postmortem biochemical processes are directly linked to final quality attributes. The understanding of postmortem mechanisms is a prerequisite for an accurate control of the quality of commercialized fish by the identification of objective markers or indicators. Postmortem tenderization is one of the most important quality attributes of fish muscle. Loss of freshness is due to a complex combination of biochemical, chemical...
Tipo: Text
Palavras-chave: Indicator; Quality; Proteolysis; Postmortem; Fish muscle.
Ano: 2006
URL: http://archimer.ifremer.fr/doc/2006/publication-1810.pdf

A marine bacterial adhesion microplate test using the DAPI fluorescent dye: a new method to screen antifouling agents
Provedor de dados: 5
Autores: Leroy, Celine; Delbarre Ladrat, Christine; Ghillebaert, F; Rochet, Marie-joelle; Compere, Chantal; Combes, D.
Aims: To develop a method to screen antifouling agents against marine bacterial adhesion as a sensitive, rapid, quantitative microplate fluorescent test.  Methods and Results: Our experimental method is based on a natural biofilm formed by mono-incubation of the marine bacterium Pseudoalteromonas sp. D41 in sterile natural sea water in a 96 wells polystyrene microplate. The 4'6-diamidino-2-phenylindole (DAPI) dye was used to quantify adhered bacteria in each well. Total measured fluorescence in wells was correlated with the amount of bacteria showing a detection limit of one bacterium per 5 µm2 and quantifying 2 x 107 to 2 x 108 bacteria adhered per cm2. The antifouling properties of three commercial surface active agents and chlorine were tested by this...
Tipo: Text
Palavras-chave: Antifouling; Pseudoalteromonas; Screening; Microtiter plate; Adhesion; DAPI; Marine biofilm.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2006/publication-2017.pdf

Characterization of New Oligosaccharides Obtained by An Enzymatic Cleavage of the Exopolysaccharide Produced by the Deep-Sea Bacterium Alteromonas infernus Using its Cell Extract
Provedor de dados: 5
Autores: Akoumany, Katy; Zykwinska, Agata; Sinquin, Corinne; Marchand, Laetitia; Fanuel, Mathieu; Ropartz, David; Rogniaux, Hélène; Pipelier, Muriel; Delbarre Ladrat, Christine; Colliec Jouault, Sylvia.
Bacteria from deep-sea hydrothermal vents constitute an attractive source of bioactive molecules. In particular, exopolysaccharides (EPS) produced by these bacteria become a renewable source of both biocompatible and biodegradable molecules. The low molecular weight (LMW) derivatives of the GY785 EPS produced by the deep-sea hydrothermal vent strain Alteromonas infernus have previously displayed some biological properties, similar to those of glycosaminoglycans (GAG), explored in cancer and tissue engineering. These GAG-mimetic derivatives are obtained through a free radical depolymerization process, which could, however, affect their structural integrity. In a previous study, we have shown that A. infernus produces depolymerizing enzymes active on its own...
Tipo: Text
Palavras-chave: Deep-sea bacterium; Alteromonas infernus; Wild-type strain; Exopolysaccharides; Glycosaminoglycan-mimetic; Enzymatic depolymerization; Structural analysis; Mass spectrometry.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00515/62644/67021.pdf

Influence of subtilisin on the adhesion of a marine bacterium which produces mainly proteins as extracellular polymers
Provedor de dados: 5
Autores: Leroy, Celine; Delbarre Ladrat, Christine; Ghillebaert, F; Compere, Chantal; Combes, D.
Aims: The nature of exopolymers involved in the adhesion of a marine biofilm-forming bacterium Pseudoalteromonas sp. D41 was investigated to evaluate and understand the antifouling potential of subtilisin.   Methods and Results: The exopolymers of D41 produced by fermentation were analysed by FTIR and SDS-PAGE showing the presence of polysaccharides, glycoproteins and proteins. A high content of proteins was detected both in soluble and capsular fractions. The microscopic observations of fluorescamine and calcofluor stained adhered D41 indicated mainly the presence of proteins in exopolymers produced during adhesion. Subtilisin, the broad spectrum protease, tested in natural sea water and in polystyrene microplates showed that antifouling activity was...
Tipo: Text
Palavras-chave: Subtilisin; Pseudoalteromonas; Exopolymer; Capsular protein; Biofilm; Antifouling.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-4624.pdf

Comparative genomics reveals a widespread distribution of an exopolysaccharide biosynthesis gene cluster among Vibrionaceae
Provedor de dados: 5
Autores: Lebellenger, Lou; Verrez-bagnis, Veronique; Passerini, Delphine; Delbarre Ladrat, Christine.
Objectives The eps locus in Vibrio diabolicus is involved in the production of the biotechnologically valuable HE800 EPS. In this study, the distribution and diversity of similar eps gene clusters across Vibrionaceae and its variability in relation to phylogenetic relationship were investigated. The aim was to provide a better knowledge of the eps gene cluster importance and to facilitate discovery of new EPS with potent interesting bioactivities. Results Seventy percent of the 103 genome sequences examined display such an eps locus with a high level of synteny. However, genetic divergence was found inside some monophyletic clades or even between some strains of the same species. It includes gene insertions, truncations, and deletions. Comparative analysis...
Tipo: Text
Palavras-chave: Vibrionaceae; Exopolysaccharide; Genetic biodiversity; Biosynthesis; Vibrio diabolicus; HE800 EPS.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00424/53536/54392.pdf