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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cultures of murine Friend erythroleukemia (FL) cells, which are chronically infected with leukemia virus, were inoculated with vaccinia virus. The yield of vaccinia virus was determined by assaying plaque-forming units in mouse L2 cells, and the yield of leukemia virus was determined by measuring reverse transcriptase (RNA-dependent DNA nucleotidyltransferase) activity released into the culture fluid. Although no facilitation of one virus by the other was detected, persistently infected cultures were established. Electron microscopic examination revealed the presence of vaccinia and leukemia viruses in the same cell. The permanent lines of cells persistently infected with vaccinia were designated FLvac. Their morphology, growth rate, cloning efficiency, and ability to respond to the induction of erythrodifferentiation by treatment with dimethyl sulfoxide were not appreciably altered as compared to the parental FL cells. However, the persistently infected cells showed a marked decrease in tumorigenicity when assayed in DBA/2 mice. The infectious virus produced by FLvac cells and by L2 cells were indistinguishable as judged by restriction endonuclease patterns of virion DNA, structural proteins, and the activities of two virion-associated DNases. The yield of infectious vaccinia virus from FLvac cells generally declined after about 60 serial passages. Although some cell lines no longer yield infectious virus, they are resistant to challenge with vaccinia at concentrations that are cytolytic for L2 cells. The mechanism responsible for the establishment of the persistent infection remains unclear because defective particles, interferon production, and temperature-sensitive mutants have not been detected.
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PMID:Persistent infection of Friend erythroleukemia cells with vaccinia virus. 695 93

Meningo-encephalitis in feedlot cattle sporadically occurred in the Tokachi area in northern Japan. The calves had been vaccinated intranasally with a mixed live-vaccine (infectious bovine rhinotracheitis virus, bovine viral diarrhea-mucosal disease virus, and parainfluenza 3 virus) for which intramuscular inoculation was indicated. Two additional live vaccines, bovine adenovirus type 7 and bovine respiratory syncytical virus, had been inoculated simultaneously. Eleven isolates of bovine herpesvirus type 1 were plaque-purified from two brains with fatal encephalitis; their viral DNAs were examined by restriction endonuclease analysis (REA) using PstI and HindIII. The REA patterns of the virus clones were almost identical to those of the vaccine strains 758-43, suggesting that the isolates from this outbreak of fatal encephalitis originated in the abnormally administered vaccine.
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PMID:Restriction endonuclease analysis of bovine herpesvirus type 1 isolates from calves with fatal encephalitis: comparison with vaccine virus. 754 27

To evaluate the possible route of transmission of Helicobacter pylori, stomach biopsies and dental plaques were cultured from patients with dyspeptic symptoms who underwent endoscopy. A total of 31 patients were examined. Twenty patients out of thirty one (64%) were H. pylori positive in gastric biopsy. Among the microorganisms isolated in dental plaque only one sample (corresponding to a patients with duodenal ulcer H. pylori positive) showed colonies morphologically and biochemically compatible with H. pylori. Proteic patterns of whole cells and restriction endonuclease analysis with Hind III and Hae III endonucleases of DNA extracted from the strain subcultured from a stomach biopsy and from dental plaque of the same patient indicated that both sites were infected with the same strain of H. pylori.
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PMID:Microbiological evidence of Helicobacter pylori from dental plaque in dyspeptic patients. 760 46

In most cases somatic mutations in disease-related genes do not give rise to a functional change of the mutated cell which would allow its isolation or expansion in vitro. Therefore, selection of mutated cells on the basis of an altered phenotype has to be replaced by biochemical separation and detection of the altered sequence of the gene of interest. In the RFLP/PCR (RFLP, restriction fragment length polymorphism) approach of 'genotypic' mutation analysis base pair changes, small deletions and insertions are measured which are located in a restriction enzyme recognition sequence and render this site resistant to cleavage by the corresponding endonuclease. The resistant DNA sequence containing the mutated site is amplified by PCR only after wild-type DNA has been eliminated by restriction digestion. Amplified DNA is directly sequenced or cloned into lambda gt10 and mutants are quantitated by oligonucleotide plaque hybridization. Absolute mutation frequencies are estimated relative to an internal 'mutant standard'. The RFLP/PCR protocol has been developed with mixtures of plasmid constructs containing wild-type inserts of the human c-H-ras1 protooncogene or inserts with base pair changes in an MspI site, a PvuII site and a TaqI site of this gene. As few as 1-5 mutated copies could be rescued from 10(7)-10(9) copies of the corresponding wild-type sequence. The RFLP/PCR protocol was successfully applied to the determination of N-ethyl-N-nitrosourea-induced mutations in codon 12 of c-H-ras1 (MspI site 1695-1698) and codon 248 of the p53 tumor suppressor gene (MspI site 14067-14070) in human skin fibroblasts. The RFLP/PCR approach holds promise for molecular toxicology and epidemiology.
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PMID:Genotypic mutation analysis by RFLP/PCR. 768 55

The gram-negative anaerobic bacterium, Fusobacterium nucleatum, is a predominant member of the human oral flora. As a major component of subgingival plaque, this bacterium has a significant impact on the ecology of the oral cavity due to its ability to adhere to many different microbial species. The objective of this study was to identify and characterize plasmids and transposons that may have the potential to be developed into tools for cloning, genetic transformation, and mutagenesis of oral isolates of F. nucleatum. Analysis of a collection of laboratory strains resulted in the identification of a homologous family of small cryptic plasmids. Plasmids within this family ranged in size from 6.0 to 6.6 kb. Eighteen percent of all strains examined (n = 74) contained DNA sequences related to the plasmids. Homologous plasmid sequences were found in strains belonging to 2 of the 3 subspecies of the bacterium. The 2 smallest plasmid species were cloned in Escherichia coli to facilitate endonuclease restriction mapping. Among the strains examined for plasmids, 5 exhibited resistance to at least 10 micrograms/ml of tetracycline. These strains, all members of the subsp. polymorphum, contained a tetracycline resistance determinant (TetM) as part of a Tn916-like integrated transposon sequence. The Tn916-like element and 1 of the plasmid species co-resided in a single strain of the bacterium. Hybridization patterns of the Tn916-like sequences were identical in all 5 tetracycline-resistant strains. However, these strains appeared to be clonally distinct based on genomic fingerprinting.
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PMID:Mobile genetic elements of Fusobacterium nucleatum. 775 5

The susceptibility of three avian cell lines (IQ1A, LMH, and QT-35) to infection by three strains of infectious laryngotracheitis virus (ILTV) was assessed both visually and by hybridization using an ILTV glycoprotein B gene probe. In the chicken liver tumor cell line (LMH), cytopathogenicity was observed at the second passage, and plaque formation was observed at the third passage. The identity of the infectious agent was verified to be ILTV by restriction endonuclease analysis of the virus genome and subsequent Southern hybridization. In contrast to LMH cells, which were a suitable host for ILTV, the quail cell line (IQ1A) was refractory to infection by this virus. Moreover, although LMH cell-adapted ILTV could initially replicate to a limited extent in the other quail cell line (QT-35), this ability was not sustained upon continual passaging.
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PMID:Propagation of infectious laryngotracheitis virus in an avian liver cell line. 798 Feb 66

The DNA of Plasmodium falciparum has been purified and fragmented with restriction endonuclease BamHI. The fragments have been incorporated in vitro into derivatives of bacteriophage lambda EMBL4 digested with BamHI and Sal I. The recombinant mixture has been ligated and packaged in vitro. The recombinant phages have been identified in E. coli L95 host cell and the libraries have been established in which most of the parasite DNA is represented. The ligation proportion of vector to insert is 3:1. The recombinant phages of 4 x 10(5) have been obtained. By plaque hybridization, we have been able to recover from these libraries specific clones containing repetitive DNA sequences.
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PMID:[The establishment of genomic DNA libraries for the human malaria parasite Plasmodium falciparum]. 817 13

Screening of a lambda gt11 genomic library has been used as an approach for molecular cloning of the Mycobacterium tuberculosis repetitive DNA shown to be present on a previously described 5.6-kb Alu I genomic fragment. The recombinant clone R18.8.2, which strongly hybridized with the radiolabeled 5.7-kb Alu fragment, carried two Eco RI inserts of 2 kb and 1.4 kb in size. Southern hybridization of each of these fragments to restriction endonuclease-cleaved M. tuberculosis DNA clearly demonstrated the 2 kb to contain the repetitive DNA sequence, while the 1.4 kb is represented in a single copy. When replica plaque lifts from the genomic library were probed, the 5.6-kb genomic fragment and the cloned 2-kb repetitive insert hybridized to an identical number of plaques, indicating the similarity and the high copy number of the repeating unit shared by the two fragments. Restriction mapping and Southern hybridization patterns indicated that the 2-kb repetitive and the 1.4-kb single-copy DNA sequences originated from a contiguous piece of genomic DNA. Both fragments were found to be unique to members of the M. tuberculosis complex, except that the 2-kb insert exhibited a weak hybridization with M. kansasii DNA. Finally, a 169-bp region from one end of the single-copy sequence has been amplified by polymerase chain reaction (PCR) in a manner specific to members of the M. tuberculosis complex. The sensitivity of the PCR was such that as few as 9-10 bacilli could be detected.
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PMID:Molecular cloning and characterization of contiguously located repetitive and single copy DNA sequences of Mycobacterium tuberculosis: development of PCR-based diagnostic assay. 837 Oct 32

Herpes simplex virus type 1 (HSV1) and type 2 (HSV2) were differentiated on the basis of different plaque appearance on semicontinuous rabbit lens epithelial (RLE) cells. Plaques produced by HSV1 strains were small; the mean diameter was 1.29 +/- 0.37 mm 3 days after inoculation. HSV2 strains produced large and small plaques, with the ratio of large to small about 20:1. The mean diameters of the large and the small plaques of HSV2 were 3.34 +/- 0.56 mm and 0.97 +/- 0.31 mm respectively 3 days after inoculation. The clones from the large plaques consistently produced large and small plaques and the small-plaque clones produced only small plaques. Round cells plus heterokaryotes were characteristic of the CPE of HSV1. Large plaques of HSV2 were produced by a large membranous syncytium that was liable to lyse. Small round cells were characteristic of the CPE of the small-plaque clones of HSV2. Glycoprotein C-negative (gC-) strains produced intermediate-sized plaques and a few pin point ones that consisted of membranous syncytia and round cells, respectively. Except for the HF strain (a reference strain of HSV1 producing a membranous syncytium on RLE cells), the result of the differentiation of HSV1 (179 strains) and HSV2 (40 strains) with the RLE plaque assay system was consistent with that of Syva's monoclonal antibody assay system and the restriction endonuclease digestion method.
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PMID:Differentiation of herpes simplex virus types 1 and 2 by plaque appearances on semicontinuous rabbit lens epithelial cells in the clinical laboratory. 839 61

The first isolation of Lactobacillus plantarum bacteriophages from ruminal fluid is reported. Three bacteriophages were characterized on the basis of plaque morphology, host ranges, stability, electron microscopic morphology and DNA restriction endonuclease digestion patterns. They formed clear plaques and are placed in group A of Bradley's scheme and have identical host ranges. Bacteriophages were stable to urea and chloroform. They were relatively thermostable but partially inactivated by rumen fluid and by acetate. DNA restriction analysis showed that phage L20 had different numbers of cleavage sites in comparison with the next two phages.
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PMID:Isolation and partial characterization of three rumen Lactobacillus plantarum bacteriophages. 851 May 72


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