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Biomedical subjects

C Madhosingh

Publications and source records attributed to C Madhosingh.

At least 19 recordsLinked to original sources
PubMed1989

Extraction and purification of DNA from phytopathogenic soil-inhabiting Fusarium species.

Working quantities of good quality DNA was obtained from three pathogenic forms of the soil-inhabiting fungus, Fusarium oxysporum (FO), which causes economically significant diseases in tomato crops. The mitochondrial, nuclear and ribosomal fractions from each of the DNAs were separated by cesium chloride gradient centrifugations. The data suggest a decrease in nuclear DNA and an increase in mitochondrial DNA correlated with increasing pathogenicity among the three pathogens examined. Ribosomal DNA was detected only in FO, the least pathogenic form.

Cell Nucleus↗
PubMed1985

Halofenate and clofibrate inhibition of pyruvate dehydrogenase from Fusarium culmorum.

Pyruvate dehydrogenase (E1, E.C. 1.2.4.1) was obtained from Fusarium culmorum by ammonium sulfate precipitation. An eight-fold purification was obtained with a specific activity of 13 K units/mg protein. Both halofenate and clofibrate inhibited the enzyme complex non-competitively. The inhibitory effect of halofenate was greater than that of clofibrate being 42% higher at 20 mM concentration compared to the inhibition by clofibrate at 40 mM concentration. Both compounds disorganized the normal cytoplasmic lipids including the emptying of cells in the mycelium suggesting membrane disruption.

Clofibrate↗
PubMed1981

Sterol ester hydrolase in Fusarium oxysporum.

Two electrophoretically different forms of sterol ester hydrolase (EC 3.1.1.13) were obtained from the cytoplasmic extract of the mycelia of Fusarium oxysporum. The entities, estimated at 60,000 (I) and 15,000 (II) molecular weights, were obtained in Sephadex G100 column chromatography of the ammonium sulfate precipitate from the cytoplasmic extract. A third form III, 75,000 MW, was obtained from the culture filtrate. The activity of the enzyme was increased by Triton X-100 and was not inhibited by p-chloromercuribenzoate (PCMB), a sulfhydryl reagent. The enzymes I and II were inhibited differentially by NaCl. The optimal activities of forms I, II and III occurred at pH 4.8, pH 8.0 and pH 7.0, respectively. The apparent Km values of 7.7 X 10(-5), 8.3 X 10(-5) and 10.5 X 10(-5), respectively, indicate a similar order of affinity for cholesteryl oleate at pH 7.1. The rate of hydrolysis of cholesteryl esters were in the order: linoleate greater than oleate greater than valerate greater than butyrate greater than acetate. Cholesteryl benzoate and palmitate were not hydrolyzed. The properties of the microbial enzyme are discussed in relation.

Carboxylic Ester Hydrolases↗
PubMed1981

Antimicrobial effects of clofibrate on the wheat pathogen Fusarium culmorum.

The biological effects of clofibrate (ethyl p-chlorophenoxy-isobutyric acid) on the growth and metabolism of the soil-borne wheat pathogen Fusarium culmorum, were examined. In mid log phase (16 hr) cultures both phenylalanine uptake and secondary spore production were stimulated at 0.1 microM concentration; the net sterol content was reduced 50% at 0.35 microM; oxygen uptake was stimulated at 0.1 mM; growth was inhibited 50% at 0.1 mM concentration. Both phenylalanine and oxygen uptake were inhibited at 1.0 mM and pyruvate dehydrogenase activity was reduced 50% at 50 mM concentration of clofibrate. The data indicate that clofibrate affects a number of biological and enzyme systems. The inhibitory effect on the growth of the pathogen suggest a potential use of hypolipidemic agents like clofibrate as an antifungal agent for seed protection.

Biological Transport, Active↗
PubMed1978

Hydroxymethylglutaryl-coenzyme A reductase. Purification and properties of the enzyme from Fusarium oxysporum.

The hydroxymethylglutaryl-coenzyme A reductase (mevalonate:NADP+ oxidoreductase, EC 1.1.1.34) system in Fusarium oxysporum, a soil inhabiting plant pathogen, has been examined. Two forms of the enzyme catalyzing the conversion of hydroxymethylglutaryl-coenzyme A were obtained in the supernatant after precipitation at 75% (NH4)2SO4 saturation of the soluble culture extract which was previously separated from cell wall, mitochondria and microsomes. The two forms of the enzyme were separated electrophoretically. A third form, contained in the precipitate obtained at 35--75% (NH4)2SO4 saturation of the same extract, was further purified by Sephadex G-50 column chromatography. This purified form moved as a single band in sodium dodecyl sulphate electrophoresis and in immunological tests and has a molecular weight of 11 000. The apparent Michaelis constant for the substrate hydroxymethylglutaryl-coenzyme A is 21 micron at 2 micron NADP. NADPH is a more efficient reductant on a molar basis than NADH for the deacylation of the hydroxymethylglutaryl-coenzyme A substrate. Optimum activity of the enzyme was obtained at pH 7.4 and 37 degrees C. The enzyme demonstrated no cold sensitivity but rather was more stable at 4 degrees C than at 25 degrees C. The protection with dithiothreitol, though minimal compared to other systems, was more effective at the higher temperature.

Fusarium↗
PubMed1975

Cell wall of Fusarium sulphureum; I. Chemical composition of the hyphal wall.

The hyphae wall of Fusarium sulphureum Schlect. (Isolate 1) was isolated and purified. Electron microscopy studies showed that the isolated cell wall consisted of two distinct layers, an outer electron dense layer and a broader electron transparent inner layer. Chemical analysis revealed that the cell wall contained 66% carbohydrate, 7.3% protein, 5.5% lipid and 1.8% ash. The major cell wall component N-acetylglucosamine (39%) was shown by X-ray diffraction analysis to be present as chitin. Glucose constituted 14% of the cell wall, while mannose, galactose, and glucuronic acid, accounted for 15% of the cell wall. Glucuronic acid appears to be predominantly linked to galactose in the intact wall.

Acetylglucosamine↗
PubMed1975

Mushroom inhibitors of dopa oxidation.

Two low molecular weight (about 1000) peptide inhibitors of dopa oxidation, purified by Sephadex chromatography, have been demonstrated electrophoretically in a preparation from the field mushroom, Agaricus hortensis.

Basidiomycota↗