Search results for "EELS"
showing 10 items of 90 documents
Toxic and enzymatic activities of Vibrio vulnificus biotype 2 with respect to host specificity
1996
In this work, the enzymatic activities of selected strains of biotypes 1 and 2 of Vabrio vulnificus were analyzed by using conventional methods and the API ZYM system. The toxic activities of extracellular products (ECPs) were further evaluated by in vitro and in vivo experiments. The ECPs of both biotypes (i) showed high-level hydrolytic activities, (ii) displayed cytotoxicity for fish cell lines, and (iii) were lethal for eels. Exotoxins seem to be proteinaceous since heat treatment of ECP samples destroyed their toxicity. Only biotype 2 strains were virulent for cels, suggesting that host specificity must be related to differences in cell surface properties. Infectivity trials with other…
Fish tolerance to organophosphate-induced oxidative stress is dependent on the glutathione metabolism and enhanced by N-acetylcysteine
2003
Abstract Dichlorvos (2,2-dichlorovinyl dimethyl phosphate, DDVP) is an organophosphorus (OP) insecticide and acaricide extensively used to treat external parasitic infections of farmed fish. In previous studies we have demonstrated the importance of the glutathione (GSH) metabolism in the resistance of the European eel ( Anguilla anguilla L.) to thiocarbamate herbicides. The present work studied the effects of the antioxidant and glutathione pro-drug N -acetyl- l -cysteine (NAC) on the survival of a natural population of A. anguilla exposed to a lethal concentration of dichlorvos, focusing on the glutathione metabolism and the enzyme activities of acetylcholinesterase (AChE) and caspase-3 a…
Utilization of hemin and hemoglobin by Vibrio vulnificus biotype 2
1996
The eel pathogen Vibrio vulnificus biotype 2 is able to use hemoglobin (Hb) and hemin (Hm) to reverse iron limitation. In this stud, the adjuvant effect of both compounds on eel pathogenicity has been evaluated and confirmed. Further, we have studied the heme-iron acquisition mechanism displayed by this bacterium. Whole cells were capable of binding Hb and Hm, independently of (i) iron levels in growth medium and (ii) the presence of polysaccharide capsules on bacterial surface. The Hb- and Hm-binding capacity was retained by the outer membrane protein (OMP) fraction and was abolished after proteolytic digestion of OMP samples. Western blotting (immunoblotting) of denatured OMPs revealed th…
Vibrio vulnificus biotype 2 serovar E gne but not galE is essential for lipopolysaccharide biosynthesis and virulence
2008
ABSTRACT This work aimed to establish the role of gne (encoding UDP-GalNAc 4-epimerase activity) and galE (encoding UDP-Gal-4-epimerase activity) in the biosynthesis of surface polysaccharides, as well as in the virulence for eels and humans of the zoonotic serovar of Vibrio vulnificus biotype 2, serovar E. DNA sequence data revealed that gne and galE are quite homologous within this species (≥90% homology). Mutation in gne of strain CECT4999 increased the surface hydrophobicity, produced deep alterations in the outer membrane architecture, and resulted in noticeable increases in the sensitivity to microcidal peptides (MP), to eel and human sera, and to phagocytosis/opsonophagocytosis. Furt…
O-Serogrouping and surface components ofAeromonas hydrophilaandAeromonas jandaeipathogenic for eels
1994
The relationship between virulence, O-serogroup, and some cell-surface features (self-pelleting [SP] and precipitation after boiling [PAB], profile of lipopolysaccharides [LPSs] and outer membrane proteins [OMPs]) was investigated in strains of the pathogenic species Aeromonas hydrophila and A. jandaei isolated from eels. Virulent strains of A. hydrophila reacted mostly with O:19 antiserum, and those of A. jandaei reacted with O:4, O:11, O:15 and O:29 antisera (Guinée and Jansen system). Regarding the PAB and LPS profiles two groups could be distinguished; (i) five PAB+ strains of serotype O:19 that possessed a homogeneous O polysaccharide side chain and (ii) thirteen PAB- strains antigenic…
The lipopolysaccharide O side chain of Vibrio vulnificus serogroup E is a virulence determinant for eels
1997
Vibrio vulnificus is a gram-negative bacterium capable of producing septicemic infections in eels and immunocompromised humans. Two biotypes are classically recognized, with the virulence for eels being specific to strains belonging to biotype 2, which constitutes a homogeneous lipopolysaccharide (LPS)-based O serogroup (which we have designated serogroup E). In the present study we demonstrated that the O side chain of this LPS determines the selective virulence of biotype 2 for eels: (i) biotype 1 strains (which do not belong to serogroup E) are destroyed by the bactericidal action of nonimmune eel serum (NIS) through activation of the alternative pathway of complement, (ii) biotype 2 str…
Farnesoid X receptor activation increases cholesteryl ester transfer protein expression in humans and transgenic mice
2013
International audience; Cholesteryl ester transfer protein (CETP) activity results in a proatherogenic lipoprotein profile. In cholestatic conditions, farnesoid X receptor (FXR) signaling by bile acids (BA) is activated and plasma HDL cholesterol (HDL-C) levels are low. This study tested the hypothesis that FXR-mediated induction of CETP contributes to this phenotype. Patients with cholestasis and high plasma BA had lower HDL-C levels and higher plasma CETP activity and mass compared with matched controls with low plasma BA (each P < 0.01). BA feeding in APOE3*Leiden transgenic mice expressing the human CETP transgene controlled by its endogenous promoter increased cholesterol within apoB-c…
Nanoscale structural and electrical properties of graphene grown on AlGaN by catalyst-free chemical vapor deposition
2020
The integration of graphene (Gr) with nitride semiconductors is highly interesting for applications in high-power/high-frequency electronics and optoelectronics. In this work, we demonstrated the direct growth of Gr on Al0.5Ga0.5N/sapphire templates by propane (C3H8) chemical vapor deposition (CVD) at temperature of 1350{\deg}C. After optimization of the C3H8 flow rate, a uniform and conformal Gr coverage was achieved, which proved beneficial to prevent degradation of AlGaN morphology. X-ray photoemission spectroscopy (XPS) revealed Ga loss and partial oxidation of Al in the near-surface AlGaN region. Such chemical modification of a 2 nm thick AlGaN surface region was confirmed by cross-sec…
Passive Behavior and Passivity Breakdown of AISI 304 in LiBr Solutions through Scanning Electrochemical Microscopy
2014
The passive behavior and passivity breakdown of AISI 304 stainless steel in LiBr solutions has been investigated by means of scanning electrochemical microscopy (SECM). The sample generation - tip collection (SG-TC) mode was used to operate the SECM and the tip potential was biased to detect the electroactive species. The evolution of the current at the ultramicroelectrode tip with the applied potential within the passive range was followed at different LiBr concentrations. Results show that the absolute value of the current at the tip increases with the applied potential. Additionally, SECM was also used to detect stable pits formed on the stainless steel surface in a 0.2 M LiBr solution. …
Multiband light emission and nanoscale chemical analyses of carbonized fumed silica
2018
Fumed silica with a specific area of 295 m2/g was carbonized by successive phenyltrimethoxysilane treatments followed by annealing in inert atmosphere up to 650 °C. Emission, excitation, kinetics, and photo-induced bleaching effects were investigated by steady state and time-resolved photoluminescence spectroscopies. The local chemistry was also studied by infrared transmission spectroscopy. Strong ultraviolet and visible photoluminescence was observed in the samples after the chemical treatments/modifications and thermal annealing. It has been shown that ultraviolet photoluminescence in chemically modified fumed silica is associated with phenyl groups, while near ultraviolet and visible em…