Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.7.1.2 (nitrate reductase)
 3,861 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rats, mice, and hamsters were fed iota-carrageenan incorporated in a fiber-free, purified diet for 30 days, and the activities of a number of cecal microbial enzymes were determined in vitro. Carrageenan treatment produced cecal enlargement in all species, yet significantly decreased the concentration of bacteria per gram of cecal content. Azoreductase, beta-glucosidase, beta-glucuronidase, nitrate reductase, and nitroreductase activities per gram of cecal content were significantly decreased in the rat, although less consistent effects were found in these enzymes in the mouse and hamster. beta-Glucuronidase and nitrate reductase functions were increased per gram of cecal contents in the hamster. The total activity per cecum of certain of these enzymes was modified by the concomitant cecal enlargement, yet total nitroreductase activity was significantly decreased in all three rodent species. iota-Carrageenan significantly decreased the concentration of enterobacteria, staphylococci, streptococci, lactobacilli, facultative anaerobes, and the total microscopic count in the rat cecum, but did not exert any effect on bacterial viability in vitro. Although having no effect on biliary IgA antibody concentration, iota- and kappa- carrageenan when present at 50 g/kg diet increased the agglutination response of the IgA specific for the hindgut microflora.
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PMID:Influence of dietary carrageenans on microbial biotransformation activities in the cecum of rodents and on gastrointestinal immune status in the rat. 404 88

Rats, mice, and hamsters were fed a fiber-free purified diet for 30 days and the activity of a number of cecal microbial enzymes was determined. Expressed per gram cecal content, azoreductase activity was greatest in preparations from the hamster and least from the mouse, and beta-glucosidase and beta-glucuronidase activities were least active from the rat. Nitroreductase was less active and nitrate reductase more active from the hamster in comparison to the other species. When expressed per kilogram body weight, bacterial activities were always greatest from the hamster. When the basal diet was supplemented with pectin (50 g/kg diet), nitrate reductase activity was increased six- to sevenfold per gram cecal content for rats and mice (tenfold when expressed per kilogram body weight), but there was no effect on the nitrate reductase activity of hamster microflora. Pectin also significantly increased beta-glucuronidase activity in rats, but significantly reduced the activities of the other enzymes in at least one of the three species.
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PMID:A comparison of the activity of five microbial enzymes in cecal content from rats, mice, and hamsters, and response to dietary pectin. 630 41

Alpha-cellulose, added to a purified diet at six levels [0%, 2.5%, 5%, 10%, 20%, and 40% (w/w)] and fed to weanling rats for 3 weeks, had no effect on body weight, but it increased the weight of caecal contents and decreased the numbers of bacteria per total caecal contents. Caecal microbial azoreductase, nitroreductase, beta-glucosidase and nitrate reductase activities per total caecal contents were also significantly decreased by 10% dietary cellulose and above, yet beta-glucuronidase activity was only affected significantly by 40% dietary cellulose. Azoreductase and nitroreductase activities were highly correlated with one another and showed a similar response to cellulose.
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PMID:Effect of dietary cellulose on the metabolic activity of the rat caecal microflora. 630 19

The enzyme activity of the rat hindgut microflora maintained in an anaerobic two-stage continuous culture was compared with that of rat cecal contents. A qualitative comparison (API ZYM) showed a high degree of similarity between the two populations. Quantitative determinations showed that azoreductase, beta-glucosidase, nitrate reductase, and nitroreductase activities were comparable, and that beta-glucuronidase activity was very low in the culture. beta-Glucuronidase, beta-glucosidase, and nitrate reductase activities were induced within the culture by their respective substrates. Bile acids influenced microbial activity in vitro, with cholic acid inducing beta-glucosidase, azoreductase, and beta-glucuronidase activities and decreasing nitrate reductase activity. Chenodeoxycholic acid increased beta-glucosidase and beta-glucuronidase activities and decreased azoreductase, nitrate reductase, and nitroreductase activities in vitro. These studies demonstrate that the rat hindgut microflora may be successfully cultured in vitro and suggest control mechanisms that regulate the metabolic activity of these organisms in vivo.
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PMID:Metabolic activity and enzyme induction in rat fecal microflora maintained in continuous culture. 641 66

Weanling or adult (9 wk old) rats were fed diets containing 0, 250 or 500 g lactose/kg for 10 days, after which the activities of six caecal microbial enzymes (azoreductase, beta-glucosidase, beta-glucuronidase, nitrate reductase, nitroreductase and urease) were determined. Adult controls had larger caeca than weanlings, but the numbers of bacteria were not significantly different. Expressed in relation to body weight, caecal microbial enzyme activities were significantly lower in adult controls, with the exceptions of beta-glucuronidase and urease. Lactose caused caecal enlargement; this was greatest in weanling animals, which also showed a decreased concentration of bacteria. Lactose increased total nitrate reductase and urease activities in both age groups, but decreased total azoreductase and nitroreductase activities in weanlings. Enzyme activities per 10(9) bacteria were decreased for azoreductase, beta-glucosidase, beta-glucuronidase and nitroreductase in both age groups, while urease activity increased. Azoreductase and nitroreductase activities were highly correlated but nitrate reductase and urease did not correlate significantly with any other enzyme activity.
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PMID:Dietary lactose and the metabolic activity of the caecal microfloras of weanling and adult rats. 642 83

Agar, carboxymethylcellulose, carrageenan, guar gum, gum acacia, locust-beam gum or pectin (50 g/kg diet), given to weanling rats for 4 wk, increased the weight of the caecal wall and the caecal contents. Feeding carboxymethylcellulose, guar gum or pectin significantly increased, and feeding carrageenan decreased, the total bacterial population of the caecum. Feeding carboxymethylcellulose significantly increased in vitro activity of bacterial azoreductase, beta-glucosidase, beta-glucuronidase, nitrate reductase, nitroreductase and urease. Guar gum, gum acacia and locust-bean gum each increased at least three of these activities. In contrast, feeding carrageenan greatly decreased all microbial enzyme activities, while agar decreased beta-glucosidase, beta-glucuronidase and nitroreductase activities.
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PMID:Hydrocolloid food additives and rat caecal microbial enzyme activities. 653 30

Weanling rats were fed low-fat (1% w/w safflower oil) or high-fat (1% w/w safflower oil plus 35% w/w beef fat or cocoa butter) diets for 30 days, and the activities of five cecal microbial enzymes were determined. When compared with the low-fat diet, beef fat significantly increased total cecal beta-glucuronidase activity, but cocoa butter, with a similar fatty acid composition, did not. Both high-fat diets significantly decreased total cecal azoreductase, beta-glucosidase, and nitrate reductase activities, but neither significantly affected urease activity. When expressed as specific activities (per 10(11) bacteria), cocoa butter decreased azoreductase, and beef fat caused increases of beta-glucuronidase and urease. Beef fat, but not cocoa butter, significantly reduced cecal bacterial numbers when compared to the low-fat diet. Both high-fat diets led to equivalent reductions in the proportion of aerobic bacteria.
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PMID:Dietary fat and cecal microbial activity in the rat. 654 72

Adult rats were fed diets containing 0, 25, 50, 100, 200, or 400 g lactalbumin/kg diet for 10 days, and the activities of six cecal microbial enzymes were determined. Total activity per cecum of azoreductase, beta-glucosidase, and urease increased significantly with increasing dietary protein, whereas the activities of beta-glucuronidase and nitroreductase were not significantly affected. Nitrate reductase activity decreased significantly. Total numbers of cecal bacteria were not significantly altered by the treatment.
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PMID:Dietary protein and cecal microbial metabolism in the rat. 687 47

The nitrate reductase (NR) gene niaA of the oomycete Phytophthora infestans was selected from a gene library by heterologous hybridization. NiaA occurs as a single-copy gene ant its expression is regulated by the nitrogen source. The nucleotide sequence of niaA was determined and comparison of the deduced amino-acid sequence of 902 residues with NRs of higher fungi and plants revealed a significant homology, particularly within the three cofactor-binding domains for molybdenum, heme and FAD. The P. infestans niaA gene was used as a model gene to test whether oomycete genes are functional in the ascomycete Aspergillus nidulans, a fungus which is highly accessible for molecular genetic studies. The complete niaA gene was stably integrated into the genome of a nia- deletion mutant of A. nidulans. However, transformants containing one or more copies of the niaA gene were not able to complement the nia- mutant. This suggests that there is no functional expression of the introduced niaA gene in A. nidulans. In addition, the activity of two other oomycete gene promoters was analyzed in a transient expression assay. Plasmids containing chimaeric genes with the promoter of the P. infestans ubiquitin gene ubi3R, or the Bremia lactucae ham34 gene, fused to the coding sequence of the Escherichia coli beta-glucuronidase (GUS) reporter gene, were transferred to A. nidulans protoplasts. No significant GUS activity was detectable indicating that the ubi3R and ham34 promoters are not active in A. nidulans. Apparently, the regulatory sequences which are sufficient for gene activation in oomycetes are not functional in the ascomycete A. nidulans.
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PMID:NiaA, the structural nitrate reductase gene of Phytophthora infestans: isolation, characterization and expression analysis in Aspergillus nidulans. 761 59

Vectors which possess a truncated niaD gene encoding nitrate reductase were developed to allow targeted gene integration during transformation of an niaD mutant Penicillium chrysogenum host. The Penicillium genes pcbC and penAB are immediately adjacent to each other and are divergently transcribed, with an intergenic control region serving as their promoters. Gene fusions were constructed with a reporter gene, uidA, which encodes beta-glucuronidase. The pcbC-penAB intergenic region was fused to the uidA gene in both orientations so that regulated expression of each structural gene could be investigated. These fusion genes were targeted to the chromosomal site of the niaD locus of P. chrysogenum, and their expression was examined under different growth conditions. The expression of each of these penicillin biosynthesis genes was found to be regulated by nitrogen repression, glucose repression, and growth stage control.
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PMID:A reporter gene analysis of penicillin biosynthesis gene expression in Penicillium chrysogenum and its regulation by nitrogen and glucose catabolite repression. 781 Oct 83


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