Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.5 (RNase)
 17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A novel replicating agent (IFDO) was isolated from ileal fluid. Growth occurred in vitro under aerobic and anaerobic conditions, and was faster at 37 degrees C than at room temperature. The doubling time was 15.8 min. Colonies were dark brown in colour and occurred beneath the surface of agar after conventional surface inoculation. Provisional data indicate that the agent may be a normal intestinal commensal. The agent was remarkably resistant to inactivation by steam at 134 degrees C, formaldehyde and glutaraldehyde; it was relatively resistant to ionising radiation, and it was filterable through membranes with a nominal pore diameter of 10 nm. Such properties, with the exception of growth in cell-free medium, are shared by "unconventional agents" such as those of Creutzfeldt-Jakob disease and scrapie. Further comparison of the properties of the intestinal agent and of slow viruses revealed additional shared characteristics, including resistance to proteinase K and trypsin, and inactivation by guanidine thiocyanate, diethyl pyrocarbonate, phenol and sodium hydroxide. The agent differs from that of scrapie in being inactivated by ethidium bromide, zinc nitrate, EDTA, hydroxylamine in the presence Sarkosyl, and, under certain circumstances, by ribonuclease. Broth cultures of the agent contained particles possessing considerable size heterogeneity. The smaller filterable particles were generally more susceptible to inactivation, did not survive autoclaving, and were inactivated by papaya protease and lipase. It is possible that the replicating agent may be formed by crystallisation from constituents of the medium, and not by a biological process. This does not exclude the postulated relationship to slow viruses.
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PMID:A novel replicating agent isolated from the human intestinal tract having characteristics shared with Creutzfeldt-Jakob and related agents. 265 97

Examination of the intestinal contents of free-living Oryzomys nigripes rats by PAGE revealed two sharply defined bands that could be stained by ethidium bromide or by silver nitrate with comparable intensities. The molecules forming these bands were susceptible to digestion by pancreatic RNase A but not by RNase T1 or by DNase I. Their lengths were estimated to be about 2.6 and 1.5 kbp, respectively, by comparison with rotavirus SA11 genome segments. They cosedimented in CsCl gradients at a density of 1.39 to 1.40 g/ml, together with uniform particles approximately 35 nm in diameter with indistinct surface structure. It is suggested that these particles represent an as yet undescribed virus with a bisegmented double-stranded RNA genome, for which the name 'picobirnavirus' is proposed.
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PMID:A virus with a bisegmented double-stranded RNA genome in rat (Oryzomys nigripes) intestines. 305 86

An optimized assay is described for the catalytic activity determination of serum ribonuclease, using polycytidylic acid as substrate and measuring the released acid-soluble ultra-violet absorbing products. Recommended final reaction concentrations are 0.3 mmol/l polycytidylic acid, 200 mmol/l imidazole/HCl buffer, pH 7.0, and 50 mmol/l NaCl. Optimal concentrations for the precipitation procedure, guaranteeing sufficient precipitation and minimal decomposition of unreacted substrate, are 160 mmol/l perchloric acid and 4 mmol/l lanthanum nitrate. Coefficients of variation for the method (within series and between days) ranged from 2.2 to 7.9%. No sex-related differences of catalytic activity were observed. In 63 blood donors with normal values of serum creatinine, the upper limit of the reference intervals (99th percentile) was 33.7 kU/l.
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PMID:An optimized micromethod for determining the catalytic activity of serum ribonuclease. 370 Dec 75

Increased message levels of testosterone-repressed prostate message-2 (TRPM-2) have been associated with programmed cell death in many tissues. To study its involvement in the apoptotic elimination of hepatocytes during liver involution and regeneration, levels of TRPM-2 message were evaluated in situ and by the ribonuclease protection assay. Although significant increases in apoptotic bodies were observed in rats 96 h following treatment with lead nitrate and ethylene dibromide, an increase in TRPM-2 message was not detected. Therefore, the expression of TRPM-2 mRNA may be a poor indicator of the extent to which apoptosis occurs during liver involution.
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PMID:Expression of TRPM-2 during involution and regeneration of the rat liver. 768 26

We have isolated the Penicillium chrysogenum nre gene which is homologous to the major nitrogen regulatory genes areA from Aspergillus nidulans and nit-2 from Neurospora crassa. Overall, nre shows 60% identity to areA and 30% identity to nit-2 at the amino-acid level. The gene encodes a protein of 835 amino-acid residues and contains a single Cys2/Cys2-type zinc finger with an adjacent basic region and a putative acidic activation region. In the DNA-binding domain, 98% of the amino-acid residues are identical in nre, areA and nit-2. The nre gene has been shown to be functional in N. crassa by heterologous complementation of a nit-2 mutant. Growth tests indicated that transformants could utilize nitrate, amino-acids, purines and amides as sole nitrogen sources. Nitrate reductase activity assays performed with transformants demonstrated that nitrogen control was completely normal. Complementation of N. crassa nit-2 mutants with 5'-deletion clones of nre suggests the possible presence of an internal promoter within the coding region. Northern analysis and ribonuclease protection assays of total cellular RNA indicated that nre encodes a 3.2-kb transcript which is reduced in content under conditions of nitrogen repression.
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PMID:Molecular cloning and analysis of nre, the major nitrogen regulatory gene of Penicillium chrysogenum. 778 18

Methylprednisolone stimulates rabbit ileal neutral NaCl absorption; and aminoglutethimide, which decreases glucocorticoid levels, decreases NaCl absorption. Studies were carried out to determine the mechanism of these effects and to determine which members of the gene family of mammalian Na+/H+ exchangers were involved. Rabbits were treated subcutaneously with methylprednisolone (40 mg daily for 24 or 72 h), aminoglutethimide (100 mg twice daily for 72 h), or saline as a control. Ileal brush border membranes were prepared by magnesium precipitation, and brush border Na+/H+ exchange was determined by 22Na+ uptake over 3-8 s. The 22Na+ uptake experiments were performed in the presence of a voltage clamp using either valinomycin/potassium or tetramethylammonium/nitrate to eliminate potential contributions by other electrogenic transport processes. Methylprednisolone treatment approximately doubled ileal brush border Na+/H+ exchange, whereas aminoglutethimide led to a 50% decrease in Na+/H+ exchange. These effects were specifically on Na+ uptake with an acid inside pH gradient, whereas diffusive Na+ uptake (no pH gradient), glucose-dependent Na+ uptake, and glucose and Na+ equilibrium volumes were not affected. To determine if the increase in Na+/H+ exchange was associated with an increase in message expression, mRNA levels were measured by ribonuclease protection assay. Methylprednisolone stimulated the NHE-3 mRNA level by 4-6-fold at 24 h, which remained increased at 72 h. In contrast, messages for NHE-1 and NHE-2 were not affected by methylprednisolone. In summary, 1) methylprednisolone stimulation of rabbit ileal Na+ absorption is due to stimulation of ileal villus cell brush border Na+/H+ exchange; 2) basal ileal brush border Na+/H+ exchange is dependent on glucocorticoid levels; and 3) an increase in NHE-3 message, but not in NHE-1 or NHE-2 message, correlates with the stimulation of ileal brush border Na+/H+ exchange. It is likely that NHE-3 is an Na+/H+ exchanger that is involved in ileal Na+ absorption.
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PMID:Glucocorticoid stimulation of ileal Na+ absorptive cell brush border Na+/H+ exchange and association with an increase in message for NHE-3, an epithelial Na+/H+ exchanger isoform. 838 Jan 55

1 The role of nitric oxide (NO) derived from constitutive and inducible nitric oxide synthase (cNOS and iNOS) and its relationship to oxygen-derived free radicals and prostaglandins (PG) was investigated in a carrageenan-induced model of acute hindpaw inflammation. 2 The intraplantar injection of carrageenan elicited an inflammatory response that was characterized by a time-dependent increase in paw oedema, neutrophil infiltration, and increased levels of nitrite/nitrate (NO2-/NO3-) and prostaglandin E2(PGE2) in the paw exudate. 3 Paw oedema was maximal by 6 h and remained elevated for 10 h following carrageenan administration. The non-selective cNOS/iNOS inhibitors, NG-monomethyl-L-arginine (L-NMMA) and NG-nitro-L-arginine methyl ester (L-NAME) given intravenously (30-300 mg kg-1) 1 h before or after carrageenan administration, inhibited paw oedema at all time points. 4 The selective iNOS inhibitors, N-iminoethyl-L-lysine (L-NIL) or aminoguanidine (AG), failed to inhibit carrageenan-induced paw oedema during the first 4 h following carrageenan administration, but inhibited paw oedema at subsequent time points (from 5-10 h). iNOS mRNA was detected between 3 to 10 h following carrageenan administration using ribonuclease protection assays. iNOS protein was first detected 6 h and was maximal 10 h following carrageenan administration as shown by Western blot analysis. Administration of the iNOS inhibitors 5 h after carrageenan (a time point where iNOS was expressed) inhibited paw oedema at all subsequent time points. Infiltrating neutrophils were not the source of iNOS since pretreatment with colchicine (2 mg kg-1) suppressed neutrophil infiltration, but did not inhibit the iNOS mRNA expression or the elevated NO2-/NO3- levels in the paw exudate. 5 Inhibition of paw oedema by the NOS inhibitors was associated with attenuation of both the NO2-/NO3- and PGE2 levels in the paw exudate. These inhibitors also reduced the neutrophil infiltration at the site of inflammation. 6 Recombinant human Cu/Zn superoxide dismutase coupled to polyethyleneglycol (PEGrhSOD; 12 x 10(3) u kg-1), administered intravenously either 30 min prior to or 1 h after carrageenan injection, inhibited paw oedema and neutrophil infiltration, but had no effect on NO2-/NO3- or PGE2 production in the paw exudate. The administration of catalase (40 x 10(3) u kg-1), given intraperitoneally 30 min before carrageenan administration, had no effect on paw oedema. Treatment with desferrioxamine (300 mg kg-1), given subcutaneously 1 h before carrageenan, inhibited paw oedema during the first 2 h after carrageenan administration, but not at later times. 7 These results suggest that the NO produced by cNOS is involved in the development of inflammation at early time points following carrageenan administration and that NO produced by iNOS is involved in the maintenance of the inflammatory response at later time points. The potential interactions of NO with superoxide anion and PG is discussed.
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PMID:Nitric oxide: a key mediator in the early and late phase of carrageenan-induced rat paw inflammation. 879 51

Because the ferric uptake regulator (fur) appears to be an essential gene in Pseudomonas aeruginosa, resistance to manganese was used as an enrichment to isolate strains carrying point mutations in the fur gene in order to assess its role in the co-ordinate expression of siderophores and exotoxin A (ETA). This report describes a detailed molecular and phenotypic characterization of four mutants and one revertant, which carry point mutations in the fur gene. Two parental strains were used in this study. Three mutants were isolated from the widely used strain, PAO1. One of these, CS (cold sensitive), has a mutation in the 5' non-coding region of the fur gene while the two other mutants derived from this parent have mutations resulting in the following deduced changes in Fur: mutant A2, H86-->R; mutant A4, H86-->Y. The other mutant (C6) and its revertant (C6Rv) were derived from PAO6261, a mutant of PAO1 with a deletion in the anr gene (anaerobic regulation of arginine deiminase and nitrate reduction) that controls anaerobic respiration in P. aeruginosa. Fur from the C6 mutant has an A10-->G mutation while in the C6Rv spontaneous revertant the mutant Gly residue has been changed to Ser at this position. All mutants were examined for alterations in the iron-regulated expression of siderophores and ETA. The A2 and A4 mutants expressed higher levels of siderophores in iron-deficient media and in iron-replete media. The CS mutant constitutively expressed siderophores at 25 degrees C. At 42 degrees C siderophore biosynthesis was iron repressed as in the parental strain PAO1. The deletion of anr in PAO6261 had no apparent effect on the iron-mediated regulation of siderophore synthesis, but the C6 mutant derived from this strain produces siderophores constitutively. The iron-regulated production of siderophores by C6Rv was similar to the parental strain PAO6261 and PAO1. Because one of the parental strains used in this study is an Anr mutant, regulation of ETA production was assessed under aerobic and microaerobic conditions. Iron-dependent repression of ETA synthesis in both parental strains and A2 and A4 mutants was found to be 50-100-fold under aerobic and microaerobic conditions, as assayed by quantitative Western dot-blot assays. By contrast in the CS and C6 mutants, while iron-dependent repression os ETA synthesis was similar to both parental strains under aerobic conditions, ETA production in these mutants was constitutive in a microaerobic environment. RNase protection analysis of toxA and regAB transcription in PAO1, PAO6261 and the C6 mutant corroborated the results of quantitative dot-blot assays of ETA. The mutant Fur proteins were purified and examined for their ability to bind to the promoter of a gene (pvdS) that positively regulates the expression of siderophores and ETA. Fur from the A2 and A4 mutants and from the C6Rv revertant was able to bind to the target DNA, but with reduced affinity by comparison to wild-type Fur. Fur from the C6 mutant in DNase I footprint experiments failed to protect the promoter region of the pvdS gene, but it retained some weak binding activity in gel mobility shift assays. The data presented in this study not only furnish some additional insights into the structure-function relationships of Fur, but also afford novel perspectives of virulence factors in P. aeruginosa under environmental conditions that have not previously been considered.
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PMID:Ferric uptake regulator mutants of Pseudomonas aeruginosa with distinct alterations in the iron-dependent repression of exotoxin A and siderophores in aerobic and microaerobic environments. 888 70

Unicellular green algae, like Chlorella, offer a potentially useful system for the expression of heterologous proteins. However, the development of Chlorella as a bioreactor has been delayed owing to the lack of a stable transformation technique. Here we report on the use of micro-projectile bombardment to introduce the nitrate reductase (NR) gene from Chlorella vulgaris into NR-deficient Chlorella sorokiniana mutants, resulting in stable transformants. The stable transformants were able to grow on nitrate medium after repeated passages between selective and nonselective medium and exhibited inducible nitrate reductase activity comparable to that of wild-type cells. Southern analysis suggests homologous recombination occurs with insertion of the wild type gene into the mutated gene and that the genes of the two Chlorellaspecies used are very similar. Specific RNase protection assays, selecting for a poorly conserved region of the gene, identified the presence of the C. vulgaris NR transcript only in the transformed C. sorkiniana mutant and not in the mutant.
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PMID:Stable Transformation of Chlorella: Rescue of Nitrate Reductase-Deficient Mutants with the Nitrate Reductase Gene 935 20

By its inability to grow on sulfate as the sole sulfur source, a mutant strain (CTNUX8) of Rhizobium etli carrying Tn5 was isolated and characterized. Sequence analysis showed that Tn5 is inserted into a cysG (siroheme synthetase)-homologous gene. By RNase protection assays, it was established that the cysG-like gene had a basal level of expression in thiosulfate- or cysteine-grown cells, which was induced when sulfate or methionine was used. Unlike its wild-type parent (strain CE3), the mutant strain, CTNUX8, was also unable to grow on nitrate as the sole nitrogen source and was unable to induce a high level of nitrite reductase. Despite its pleiotropic phenotype, strain CTNUX8 was able to induce pink, effective (N2-fixing) nodules on the roots of Phaseolus vulgaris plants. However, mixed inoculation experiments showed that strain CTNUX8 is significantly different from the wild type in its ability to nodulate. Our data support the notion that sulfate (or sulfite) is the sulfur source of R. etli in the rhizosphere, while cysteine, methionine, or glutathione is supplied by the root cells to bacteria growing inside the plant.
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PMID:A cysG mutant strain of Rhizobium etli pleiotropically defective in sulfate and nitrate assimilation. 939 98


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