Metabolism of 2-deoxy-2-fluoro-D-[3H]glucose and 2-deoxy-2-fluoro-D-[3H]mannose in yeast and chick-embryo cells.

2-Deoxy-2-fluoro-D-[3H]glucose and 2-deoxy-2-fluoro-D-[3H]mannose have been prepared by tritiation of the corresponding unlabeled 2-fluoro sugars. The tritiated 2-fluoro sugars are phosphorylated and activated by UTP and by GTP to yield UDP-2-deoxy-2-fluoro-D-[3H]glucose, UDP-2-deoxy-2-fluoro-D-[3H]mannose, GDP-2-deoxy-2-fluoro-D-[3H]glucose and GDP-2-deoxy-2-fluoro-D-[3H]mannose in both cell types. The nucleotide derivatives could also be labeled in the nucleotide moiety by feeding the cells with [14C]uridine or [14C]guanosine in the presence of unlabeled 2-fluoro sugar. No evidence was obtained for metabolic steps in which the six-carbon chain of 2-fluoro sugars was not preserved. No epimerisation of the label to 2-deoxy-2-fluoro-D-[3H]galactose could be observed by radioactive gas-liquid chromatography of the enzymatic cleavage products of the different 2-fluoro sugar metabolites isolated from either cell type. Yeast and chick embryo cells both incorporate 2-deoxy-2-fluoro-D-[3H]glucose and 2-deoxy-2-fluoro-D-[3H]mannose specifically into glycoproteins, although this incorporation is very low when compared to the incorporation of 2-deoxy-D-[3H]glucose.     

Fluorosugars inhibit biological properties of different enveloped viruses.

Both 2-deoxy-2-fluoro-D-glucose and 2-deoxy-2-fluoro-D-mannose were found to be potent inhibitors of the synthesis of infectious Semliki forest and fowl plague virus in chicken embryo cells and also of pseudorabies virus grown in rabbit kidney cells. It was found that the pseudorabies virus-mediated cell fusion and the synthesis of functional hemagglutinin of fowl plague virus were blocked. In all cases the 2-deoxy-2-fluoro-D-mannose-caused inhibition was stronger than the 2-deoxy-2-fluoro-D-glucose- or 2-deoxy-D-glucose-mediated blocks. Studies on the virus-specified proteins from Semiliki forest virus-infected cells grown in the presence of the inhibitors show that the target of the fluorosugar action, parallel to the well-studied effects of 2-deoxy-D-glucose, is the glycoprotein biosynthesis.     

Some general aspects regarding the interpretation of binding data by means of a Scatchard plot

The question is quantitatively examined which general information can be obtained from experimental data of ligand binding to macromolecules if represented by a Scatchard plot. In particular, the curvature as well as the intercepts and slopes at both coordinate axes are analyzed assuming rather general conditions including cooperative behavior (with applications to some simplified cases of interest in practice). The results should provide a basis for attempts to elucidate the binding mechanism of a system encountered in experimental work.     

Studies on the interaction of cholesterol with diester- and dietherlecithin

The lamellar repeat distances of aqueous dispersions of rac-1,2-dioctadec-9′-cis-enyl-glycero-3-phosphorylcholine (dietherlecithin) and 1,2-dioctadec-9′-cis-enoyl-sn-glycero-3-phosphorylcholine (diesterlecithin) have been measured by X-ray diffraction as a function of water concentration. The point of maximum hydration was found to be 43% (w/w) and 40% (w/w) for dietherlecithin and diesterlecithin respectively; the corresponding lamellar repeat distances being 62.3 Å and 60.5 A. Incorporation of cholesterol above maximum hydration results in the initial increase in the lamellar repeat distance with a maximum around cholesterol concentrations of 25 and 33 mol % for dietherlecithin and die diesterlecithin respectively.The apparent partial specific volumes of the two lecithins and for lecithin-cholesterol mixtures in sonicated aqueous dispersions were measured. Values of 1.024 cm³ · g^?1 and 0.987 cm³ · g^?1 were obtained for diether- and diesterlecithin, respectively, at 20°C. Diesterlecithin-cholesterol mixtures showed a very small change in partial specific volume while mixtures of dietherlecithin-cholesterol showed a very marked decrease with increasing proportions of cholesterol.From these data a series of structure parameters are derived for the two lecithins and possible implications for the nature of the lecithin-cholesterol interaction are discussed.     

Heterotrophic Activity of Deep-Sea Sediment Bacteria

Sediment samples, containing mixed microbial populations that were decompressed during retrieval from 7,750 and 8,130 m in the Puerto Rican Trench, were recompressed and incubated at the approximate in situ temperature (3 C) and pressure (775 or 815 atm) in the presence of 14C-labeled amino acids. Heterotrophic activity (total uptake, CO2 respiration, and cellular assimilation) and cellular-associated "pool" concentrations were measured. Compared with atmospheric controls held at 3 C, the total uptake at elevated pressure at 3 C was reduced, on an average, 55 times, CO2 respiration was reduced 45 times, and cellular assimilation was reduced 69 times. Rate of total uptake at elevated pressure was found to range from 4.0 X 10(-11) mug/cell per h for leucine to 2.61 X 10(-10) mug/cell per h for an amino acid mixture. Also, the percentage of total uptake at elevated pressures, respired as CO2, increased at the expense of cellular assimilation (ca. 22% increase). Two cellular-associated amino acid pools were detected, a large, loosely bound, outer pool and a small, tightly bound internal pool. The loosely bound outer pool was removed by a change in the pH of the incubation medium. Even though heterotrophic uptake and the outer, cellular-associated pool were markedly reduced at an elevated pressure, the percentage of total uptake calculated for the unincorporated, tightly bound, intracellular pool was 2 to 19 times that obtained for cultures held at 1 atm. The results were interpreted as indicating that bacterial metabolism and biosynthesis in the deep sea are markedly reduced, with a greater proportion of metabolic activity devoted to cellular maintenance.     

Hinweis auf abnorme Kernverhältnisse im Endospermhäutchen vonFritillaria imperialis

Ohne Zusammenfassung     

Effects of pentachlorophenol and some of its known and possible metabolites on different species of bacteria.

The antibacterial activity of pentachlorophenol and 35 of its known or possible metabolites against 30 different species of bacteria was tested. In comparison with pentachlorophenol, no increase of inhibitory activity was found for any of the chlorinated anisoles tested (except for pentachloroanisole against Streptomyces spp.), 2-chlorophenol, 2,6-dichlorophenol, 2,3,6- and 2,4,6-trichlorophenol, 2,3,5,6-tetrachlorophenol, tetrachloro-1,4- and -1,3-benzenediol (except for the 1,3-isomer against Streptomyces spp.), tetrachloro-1,3-dimethoxybenzene, and tetrachloro-1,3-benzenediol diacetate. Two chlorophenols, five dichlorophenols, four trichlorophenols, two tetrachlorophenols, and tetrachloro-1,2-benzenediol were more active than pentachlorophenol against some, but not all, of the strains tested.