Sources partitioning in the diet of the shipworm Bankia carinata (J.E. Gray, 1827): An experimental study based on stable isotopes.

Adaptations that allow teredinids to maintain and thrive on wood, a nutritionally unbalanced food, make these marine bivalves remarkable. Capable of filter-feeding, shipworms house endosymbiotic bacteria synthesizing cellulolytic enzymes for digestion of wood carbohydrates and providing nitrogen to their host through nitrogen fixation. To what extent each of these nutrition modes contributes to the shipworm's metabolism remains an open question.

Genetic diversity and phenotypic plasticity of AHL-mediated Quorum sensing in environmental strains of Vibrio mediterranei.

N-Acyl homoserine lactone (AHL)-mediated Quorum sensing (QS) is one of the most studied social behavior among Proteobacteria. However, despite the current knowledge on QS-associated phenotypes such as bioluminescence, biofilm formation, or pathogenesis, the characterization of environmental factors driving QS in realistic ecological settings remains scarce. We investigated the dynamics of AHL and AHL-producing Vibrio among 840 isolates  collected fortnightly from the Salses-Leucate Mediterranean lagoon in spring and summer 2015 and 2016.

Characterization and sources of colored dissolved organic matter in a coral reef ecosystem subject to ultramafic erosion pressure (New Caledonia, Southwest Pacific).

The eastern lagoon of New Caledonia (NC, Southwest Pacific), listed as a UNESCO World Heritage site, hosts the world's second longest double-barrier coral reef. This lagoon receives river inputs, oceanic water arrivals, and erosion pressure from ultramafic rocks, enriched in nickel (Ni) and cobalt (Co). The aim of this study was to characterize colored dissolved organic matter (CDOM), as well as to determine its main sources and its possible relationships (through the use of Pearson correlation coefficients, r) with biogeochemical parameters, plankton communities and trace metals in the NC eastern lagoon.

Dynamics of phytoplankton communities in eutrophying tropical shrimp ponds affected by vibriosis.

Tropical shrimp aquaculture systems in New Caledonia regularly face major crises resulting from outbreaks of Vibrio infections. Ponds are highly dynamic and challenging environments and display a wide range of trophic conditions. In farms affected by vibriosis, phytoplankton biomass and composition are highly variable.

Impact of lower salinity waters on bacterial heterotrophic production and community structure in the offshore NW Mediterranean Sea.

We investigated the impact of water masses originating from freshwater input on bacterial heterotrophic metabolism and community structure at an offshore site in the oligotrophic NW Mediterranean Sea in 2007 and 2008. By combining 16S rRNA gene clone libraries and MICRO-CARD-FISH we determined the dominant operational taxonomic units (OTU) and their contribution to bulk abundance and activity in the presence of buoyant water masses characterized by lower salinity (LSW, < 37.9) and compared these with the winter and spring phytoplankton blooms.

Photodegradation of sulcotrione in various aquatic environments and toxicity of its photoproducts for some marine micro-organisms.

Photochemical behaviour of sulcotrione, a triketone herbicide, was studied in a variety of aqueous solutions including natural waters (sea and river) under laboratory conditions. Photodegradation experiments were carried out under two irradiation systems (UV-B and simulated solar radiation) in order to evaluate kinetics of active ingredient. The degradation kinetics, more rapid under UV-B radiation than solar simulator, followed a first-order reaction (photolysis half-lives ranged between 3 and 50 h) and appeared strongly dependent on water origin, pH value and molecular structure of the herbicide.

Electrochemical detection of nitric oxide production in human polymorphonuclear neutrophil leukocytes.

The detection of nitric oxide (NO) release by human polymorphonuclear neutrophil leukocytes (PMNs) presents several difficulties, mainly due to concomitant production of O2- and H2O2, which could interfere with the measurements. A Nafion and nickel porphyrin-coated microelectrode was used to measure NO production in PMNs in vitro. It allowed detection of 6.

Activation of nitric oxide release and oxidative metabolism by leukotrienes B4, C4, and D4 in human polymorphonuclear leukocytes.

Because arachidonate metabolites are potent mediators of inflammation, we have studied the effects of leukotriene B4 (LTB4) and the cysteinyl leukotrienes C4 and D4 (LTC4 and LTD4) on the release of nitric oxide (NO), in vitro, by human polymorphonuclear granulocytes (PMN). Two independent and highly sensitive real-time methods were used for these studies, ie, the NO-dependent oxidation of oxyhemoglobin (HbO2) to methemoglobin and a NO-sensitive microelectrode. When activated with LTB4, LTC4, or LTD4, but not with other lipoxygenase products such as 5S-HETE, 5-oxo-ETE or 5S, 12S-diHETE, PMN produced NO in a stimulus- and concentration-dependent manner.

Inhibition by cholesterol oxides of NO release from human vascular endothelial cells.

Recent studies have demonstrated that, unlike cholesterol, cholesterol oxidized at position 7 can reduce the maximal endothelium-dependent relaxation of isolated rabbit aortas (Circulation. 1997;95:723-731). The aim of the current study was to determine whether cholesterol oxides reduce the release of nitric oxide (NO) from human umbilical vein endothelial cells (HUVECs).

Nitric oxide production in human endothelial cells stimulated by histamine requires Ca2+ influx.

The causal relationships between cytosolic free-Ca2+ concentration ([Ca2+]i) increases and production of nitric oxide (NO) have been investigated mostly with indirect methods and remain unclear. Here we demonstrate, by direct real-time measurements of [NO] with a porphyrinic microsensor, that Ca2+ entry, but not an increase in [Ca2+]i, is required for triggering of NO production in human endothelial cells. Histamine, ranging from 0.

Nitric oxide production by endothelial cells: comparison of three methods of quantification.

Vascular endothelial cells have been found to produce a relaxant mediator, identified as nitric oxide (NO) and implicated in numerous physiological functions. Subsequently, there has been an intensive search for accurate and specific detection methods to measure biological NO production. In the present study, we compared three approaches to evaluate NO production, based respectively on the Griess reaction (that quantifies nitrites and nitrates after their reduction), on the hemoglobin reaction (that quantifies oxyhemoglobin to methemoglobin transformation by NO), and on the electrochemical NO detection with a porphyrinic micro-probe.

Elaboration and use of nickel planar macrocyclic complex-based sensors for the direct electrochemical measurement of nitric oxide in biological media.

We describe here the electrochemical detection of nitric oxide, NO, in biological systems by using chemically modified ultramicro carbon electrodes. In the first part of the paper, the different steps involved in the electrochemical preparation and characterization of the nickel-based sensor are described. This is illustrated by the use of nickel(II) tetrasulfonated phthalocyanine complex.

SK&F 96365 inhibits intracellular Ca2+ pumps and raises cytosolic Ca2+ concentration without production of nitric oxide and von Willebrand factor.

The effects of the imidazole compound SK&F 96365 on Ca2+ movements and production of nitric oxide (NO) and von Willebrand factor (vWF) have been investigated in human endothelial cells. Changes in cytosolic Ca2+ concentration ([Ca2+]i) were measured with Fura-2. Real-time production of NO was monitored with a porphyrinic microsensor and the release of vWF with an enzyme-linked immunosorbent assay.

Influence of authentic nitric oxide on basal cytosolic [Ca2+] and Ca2+ release from internal stores in human platelets.

1. Nitric oxide (NO) donors inhibit platelet function and Ca2+ mobilization evoked by different agonists. This led us to investigate the direct effects of authentic NO on basal cytosolic Ca2+ concentration ([Ca2+]i) and on Ca2+ mobilization induced by thrombin or by two inhibitors of intracellular Ca(2+)-ATPases, thapsigargin and 2,5-di-(t-butyl)-1,4-benzohydroquinone (t-BuBHQ).

Human immunoglobulins inhibit thrombin-induced Ca2+ movements and nitric oxide production in endothelial cells.

Binding of natural antibodies to endothelial cell plays an important role in hyperacute xenograft rejection between discordant species. Human intravenous immunoglobulins (IVIg) delay this hyperacute rejection, but their mechanisms of action on endothelial cells have to be defined. Here we demonstrate that IVIg dose-dependently prevent thrombin from eliciting cytosolic Ca2+ movements and nitric oxide (NO) production in aortic endothelial cells from guinea pig.

Nitric oxide inhibits ATP-dependent Ca2+ uptake into platelet membrane vesicles.

The reduction by nitric oxide donors of Ca2+ mobilization in stimulated platelets lead us to investigate the direct effect of authentic NO on ATP-dependent Ca2+ uptake into platelet membrane vesicles. The effects of NO were compared to those of thapsigargin and 2,5-di-(t-butyl)-1,4-benzohydroquinone, two specific inhibitors of the sarco/endoplasmic reticulum Ca2+-ATPases. All three compounds modulated the initial rate of ATP-dependent Ca2+ uptake.

Direct measurement of nitric oxide production in platelets: relationship with cytosolic Ca2+ concentration.

NO production in platelets has been followed by electrochemical detection. It was undetectable in unstimulated platelets and in thrombin or ADP-stimulated platelets, but dose-dependently stimulated by collagen. A production of 5 10(-19) mol/platelet was reached with 9 micrograms collagen.