Mercury methylation and demethylation rates were measured in periphyton biofilms growing on submerged plants from a shallow fluvial lake located along the St. Lawrence River (Quebec, Canada). Incubations were performed in situ within macrophytes beds using low-level spikes of (199)HgO and Me(200)Hg stable isotopes as tracers. To determine which microbial guilds are playing a role in these proce...

Molybdenum is absolutely required for the nitrate-reducing activity of the nicotinamide adenine dinucleotide nitrate reductase complex isolated from Chlorella fusca. The whole enzyme nicotinamide adenine dinucleotide nitrate reductase is formed by cells grown in the absence of added molybdate, but only its first activity (nicotinamide adenine dinucleotide diaphorase) is functional. The second a...

The fates and the rates of metabolism of acetate, trimethylamine, methylamine, and methanol were examined to determine the significance of these compounds as in situ methane precursors in surface sediments of an intertidal zone in Maine. Concentrations of these potential methane precursors were generally <3 muM, with the exception of sediments containing fragments of the seaweed Ascophyllum nod...

Two years ago, a modification (1) of the Bell-Doisy phosphate method was published and at that time technique ‘was given for its application to inorganic phosphorus in blood and urine. Since then its use has been extended to a variety of analytical procedures, some of which are given below. In principle the method consists of the formation of phosphomolybdic acid and its subsequent reduction by...

The modABC gene products constitute the molybdate-specific transport system in Escherichia coli. Another operon coding for two proteins which diverges from the modABCD operon has been identified. The first gene of this operon codes for a 262-amino-acid protein, designated ModE (28 kDa), and the second genes codes for a 490-amino-acid protein. ModF (54 kDa). The role of ModF has not yet been det...

Cicer Arietinum (Leguminosae) is an annual herb, known as local Indian name ‘Kala Chana’. Its root was extracted using solvents of different polarities and explored for invitro free radical scavenging activity. Preliminary assays of three different extracts of Cicer Arietinum root, scavenges 1, 1-diphenyl-2-picrylhydrazyl stable free radicals in concentration dependent manner. All studied extra...

Experiments were conducted to study the ability of surfactant-modified clinoptilolite for molybdate adsorption from aqueous solutions. Clinoptilolite was treated with some cationic surfactants. Adsorption of surfactants on zeolite surface was confirmed by chemical analysis, IR (Infra-Red Spectroscopy), DTG (Derivative Thermogravimetry) and SEM (Scanning Electron Microscopy) techniques. The modi...

Laser Raman spectra, UV-visible spectra, and photo-catalytic activity measurements are described which show that supported MoO,iTiOr catalysts prepared by impregnation possess a layer of surface molybdate species coordinated to the titania support. The saturation coverage of this surface molybdate monolayer corresponds to a surface density of ca. 4 x lOI MO atoms per cm2 of TiO*. The properties...

Two years ago, a modification (1) of the Bell-Doisy phosphate method was published and at that time technique ‘was given for its application to inorganic phosphorus in blood and urine. Since then its use has been extended to a variety of analytical procedures, some of which are given below. In principle the method consists of the formation of phosphomolybdic acid and its subsequent reduction by...