Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.31 (beta-glucuronidase)
7,680 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of the study was to compare the physiological consequences of two dietary fibre sources on the faecal microflora and colonic mucosal growth in rats. The studied sources, a moderately well-soluble fibre (rice bran, RB) and a less well-soluble fibre (wheat bran, WB), were included in diets of rats at a level of 10% for 3 weeks and compared with a totally fibre-deprived diet. RB significantly increased faecal water compared to the control diet (p < 0.05). Faecal nitrogen content and bacterial mass, as estimated from the 2,6-diaminopimelic acid (DAPA) output, were greatly and significantly increased by RB, and to a lesser extent by WB, compared to the control diet. Total bile acid excretion was significantly higher by rats fed RB than by those fed WB. Faecal bacterial enzyme activities tested (beta-glucuronidase, mucinase and nitroreductase) were significantly reduced by the two different fibre sources, but RB was more effective than WB, except for nitroreductase activity which was reduced at the same level for each fibre source. Although measurements of mucosal colonic weight and RNA content were significantly different between groups fed RB and WB (p < 0.05), DNA content and the ratio RNA/DNA did not significantly differ between these groups. Our results indicate that the differential changes observed in beta-glucuronidase and mucinase activities and DAPA and bile acid excretion may depend on the nature of the fibre consumed. They also suggest that RB, which had similar effects, sometimes more marked than WB, on the studied parameters, may be a new valuable fibre source.
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PMID:Comparative evaluation of the effects of two different forms of dietary fibre (rice bran vs. wheat bran) on rat colonic mucosa and faecal microflora. 753 89

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

All ribosomal protein (rp) gene promoters from Saccharomyces cerevisiae studied so far contain either (usually two) binding sites for the global gene regulator Rap1p or one binding site for another global factor, Abf1p. Previous analysis of the rpS33 and rpL45 gene promoters suggested that apart from the Abf1 binding site, additional cis-acting elements play a part in transcription activation of these genes. We designed a promoter reconstruction system based on the beta-glucuronidase reporter gene to examine the role of the Abf1 binding site and other putative cis-acting elements in promoting transcription. An isolated Abf1 binding site turned out to be a weak activating element. A T-rich sequence derived from the rpS33 proximal promoter was found to be stronger, but full transcription activation was only achieved by a combination of these elements. Both in the natural rpL45 promoter and in the reconstituted promoter, a Rap1 binding site could functionally replace the Abf1 binding site. Characteristic rp gene nutritional control of transcription, evoked by a carbon source upshift or by nitrogen re-feeding to nitrogen starved cells, could only be mediated by the combined Abf1 (or Rap1) binding site and T-rich element and not by the individual elements. These results demonstrate that Abf1p and Rap1p do not activate rp genes in a prototypical fashion, but rather may serve to potentiate transcription activation through the T-rich element.
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PMID:Transcription activation of yeast ribosomal protein genes requires additional elements apart from binding sites for Abf1p or Rap1p. 778 99

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

Extracellular lipo-oligosaccharides of Rhizobium, known as Nod factors, play a key role in the molecular signal exchange which leads to the specific nitrogen-fixing symbiotic association between the soil microbe and its host legume. The biological activity of Nod factors and their perception by the host plant during the earliest stages of the Rhizobium/legume interaction have been studied using transgenic alfalfa carrying a fusion between the promoter of the early nodulin gene MtENOD12 and the beta-glucuronidase (GUS) reporter gene. Histochemical staining has shown that GUS accumulates specifically in the differentiating root epidermis, prior to and during root hair emergence, within 2-3 h following the addition of purified Rhizobium meliloti Nod factors. This precocious transcriptional activation of the MtENOD12 gene, reminiscent of that observed after inoculation with intact Rhizobium, implies that the Nod factor signal can be perceived at a developmental stage preceding root hair formation. GUS activity can be detected following treatment with a wide range of R. meliloti Nod factor concentrations down to 10(-13) M, and furthermore, this rapid response to the bacterial elicitor appears to be non-systemic. Significantly, MtENOD12-GUS expression is not observed after inoculation with a R. meliloti nodH mutant which synthesizes exclusively non-sulphated Nod factors. Indeed purified Nod factors which lack the sulphate substituent are approximately 1000-fold less active than their sulphated counterparts. Thus, the triggering of ENOD12 transcription in the alfalfa root epidermis is a rapid molecular response which is subject to the same host-specificity determinant (Nod factor sulphation) that governs the interaction between alfalfa and its bacterial symbiont.
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PMID:Rhizobium meliloti Nod factors elicit cell-specific transcription of the ENOD12 gene in transgenic alfalfa. 792 Jul 14

The glucuronidation of the food-borne heterocyclic amine 2-amino-1-methyl-6-phenylimidazo-[4,5-b]pyridine (PhIP) was investigated using hepatic microsomes from several species. PhIP-glucuronic acid conjugates were formed in an NADPH-free system using microsomes from rabbit, dog, guinea pig, and human. Rat, hamster, and mouse microsomes were incapable of directly producing PhIP-glucuronides. The PhIP-glucuronide generated with human microsomes could be resolved by reverse-phase HPLC from that produced with rabbit microsomes. In addition, the human PhIP-glucuronide was susceptible to enzymatic hydrolysis by beta-glucuronidase, whereas the rabbit PhIP-glucuronide did not undergo beta-glucuronidase catalyzed hydrolysis. Fast atom bombardment mass spectrometry of both glucuronides revealed the presence of ions with m/z 401 (M+H+). Rabbit PhIP-glucuronide had a lambda max of 316 nm, similar to that of the parent PhIP. By contrast, a spectral shift in UV absorbance was observed for the human PhIP-glucuronide, which had a lambda max of 305 nm. 1H-NMR spectroscopy and nuclear Overhauser enhancements established that rabbit PhIP-glucuronide was conjugated at the exocyclic amine nitrogen, whereas human PhIP-glucuronide was conjugated at the N3 imidazole ring nitrogen. Km values for PhIP were 0.2-0.3 mM in both species; however, rabbit microsomes exhibited a 22-fold higher Vmax. Collectively, these studies indicate that human and rabbit liver microsomes form structurally different glucuronides of PhIP and suggest the involvement of multiple isoforms of UDP-glucuronosyltransferase. Further, these data suggest that in certain species, including humans, the direct conjugation of PhIP with glucuronic acid may represent a primary route of PhIP metabolism and detoxication.
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PMID:The direct glucuronidation of 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine (PhIP) by human and rabbit liver microsomes. 811 24

The nature of the compartmentalization of catalase in human myeloid cells is an unresolved issue. Using a rabbit polyclonal antibody specific for catalase, indirect immunocytofluorescence of immature leukemic promyelocytes (HL-60 cells) showed a pattern of small, sharp, punctate staining in the cytoplasm of all cells, while mature neutrophils showed a larger diffuse, flocculent pattern of cytoplasmic staining. Differential centrifugation of nitrogen cavitates of HL-60 cells indicated that the putative catalase-containing compartment was relatively fragile compared with the compartment(s) that contained myeloperoxidase (MPO), beta-hexosaminidase, beta-glucuronidase, and lysosomal alpha-mannosidase activities. Parallel studies using dimethylsulfoxide (DMSO)-induced HL-60 cells and mature neutrophils showed that, in the course of differentiation, there was an apparent shift in the localization of catalase from the granule fraction to the cytosolic fraction. Percoll-sucrose density gradient centrifugation of HL-60 cell cavitates showed a catalase-containing compartment with a mean peak density (1.05 g/mL) significantly lower than that of the major myeloperoxidase-containing compartment (1.08 g/mL); in mature neutrophils, catalase activity comigrated with lactate dehydrogenase (LDH) activity. Catalase in isolated fractions was protected from proteolysis in the absence, but not in the presence, of 0.1% Triton X-100. Digitonin titration experiments confirmed the compartmentalized nature of catalase in immature HL-60 cells and were consistent with a cytosolic localization in mature neutrophils. Ultrastructural localization of catalase by Protein A-gold immunocytochemistry demonstrated four to six catalase-containing compartments in all HL-60 cell profiles. In mature neutrophils, catalase was localized primarily in the cytoplasmic matrix, although in fewer than 2% of the cell profiles, one to two catalase-containing compartments were observed. The changes in catalase localization that occur during myeloid differentiation appear to be similar to the changes that occur during erythroid and megakaryocytic differentiation, and may have potential clinical significance in the classification of acute leukemia and in the development of drug resistance.
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PMID:Changes in the localization of catalase during differentiation of neutrophilic granulocytes. 816 45

The avirulence gene avr9 of the fungal tomato pathogen Cladosporium fulvum encodes a race-specific peptide elicitor that induces the hypersensitive response in tomato plants carrying the complementary resistance gene Cf9. The avr9 gene is not expressed under optimal growth conditions in vitro, but is highly expressed when the fungus grows inside the tomato leaf. In this paper we present evidence for the induction of avr9 gene expression in C. fulvum grown in vitro under conditions of nitrogen limitation. Only growth medium with very low amounts of nitrogen (nitrate, ammonium, glutamate or glutamine) induced the expression of avr9. Limitation of other macronutrients or the addition of plant factors did not induce the expression of avr9. The induced expression of avr9 is possibly mediated by a positive-acting nitrogen regulatory protein, homologous to the Neurospora crassa NIT2 protein, which induces the expression of many genes under conditions of nitrogen limitation. The avr9 promoter contains several putative NIT2 binding sites. The expression of avr9 during the infection process was explored cytologically using transformants of C. fulvum carrying an avr9 promoter-beta-glucuronidase reporter gene fusion. The possibility that expression of avr9 in C. fulvum growing in planta is caused by nitrogen limitation in the apoplast of the tomato leaf is discussed.
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PMID:Nitrogen limitation induces expression of the avirulence gene avr9 in the tomato pathogen Cladosporium fulvum. 819 81

Nitrate (NR) and nitrite reductase (NiR) catalyse the reduction of nitrate to ammonium. The regulation of NR and NiR gene expression by carbohydrates (C) and nitrogen (N) metabolites was studied using detached leaves. In the dark, glucose fructose and sucrose supplied to detached green leaves of dark-adapted Nicotiana plumbaginifolia plants resulted in NR mRNA and protein accumulation and the loss of circadian rhythmicity in the size of the transcript pool. The characterization of transgenic plants expressing either a NR cDNA controlled by the 35S CaMV promoter or a transcriptional fusion between the tobacco nia1 (NR structural gene) promoter and the beta-glucuronidase reporter gene, led us to conclude that C metabolite control is taking place at the transcriptional level. Under low light conditions (limiting photosynthetic conditions), the supply of glutamine or glutamate resulted in a drop in the level of NR mRNA. Exogenously supplied carbohydrates partially antagonized this inhibitory effect suggesting that the availability of N and C metabolites affects the expression of the NR gene. The effects of carbohydrates and glutamine on NiR expression were also studied. NiR mRNA levels in the dark were relatively insensitive to feeding with glucose. Glutamate and glutamine were less efficient at decreasing NiR mRNA than NR mRNA levels. In contrast to NR, NiR mRNA levels were significantly increased by light treatments, indicating that NiR display regulatory characteristics reminiscent of photosynthetic genes such as the small subunit of ribulose bisphosphate carboxylase than to NR.
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PMID:Regulation of nitrate and nitrite reductase expression in Nicotiana plumbaginifolia leaves by nitrogen and carbon metabolites. 822 Apr 46

The beta-glucuronidase (GUS) activity expressed from the soybean early nodulin ENOD2(B) gene promoter was localized histochemically in nodules of Lotus corniculatus and Trifolium repens. In both the determinate Lotus nodules and the indeterminate Trifolium nodules, activity was found in the parenchyma cells and especially in cells close to the vascular tissue of nodules. The characteristic cell-specific expression of the soybean ENOD2 gene was therefore maintained by the ENOD2(B) promoter in the two developmentally different nodule types. Important DNA elements recognized in transgenic nodules were identified by deletion and hybrid promoter analysis in Lotus corniculatus. An indispensable positive element (PE) and a possible tissue specific element was defined between positions -1792 and -1582 from the transcription start site. Another qualitative control element located between -380 and -53 conferred the ENOD2 characteristic cell type expression on hybrid promoters. This element contains the conserved nodulin gene sequences CTCTT and AAAGAT. In contrast to the ENOD2(B) promoter a chimeric leghemoglobin Ibc3-GUS gene was expressed in the infected cells of both types of nodules. In the indeterminate nodules expression was restricted to the interzone II-III and the active nitrogen-fixing zone III. Interchange of the distal strong positive element (SPE) of Ibc3 and the ENOD2 positive element resulted in an expression pattern different from that observed for the Ibc3 and ENOD2 genes, indicating that different interactions of trans-acting factors are required for regulation of early as well as late nodulin genes.
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PMID:Conserved regulation of the soybean early nodulin ENOD2 gene promoter in determine and indeterminate transgenic root nodules. 822 Apr 55


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