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)

A nuclear polyhedrosis virus (MNPV) isolated from a lepidopteran (Noctuidae) insect, Autographa californica, was cloned by successive plaque purification using virions containing only one nucleocapsid per envelope as inoculum. The ability to clone the virus by this method was demonstrated by the isolation of nondefective, genotypic variants of the virus with similar but not identical restriction endonuclease fragment patterns. Five distinct variants were identified by genotypic analysis with HindIII, EcoRI, SalI, and Bam HI restriction endonucleases. The characteristic genotype of each variant was maintained upon passage in insect larvae. The isolation of these virus variants demonstrates (i) the heterogeneity of the uncloned virus preparation and (ii) the ability to clone MNPVs by plaque purification of media-derived nonoccluded virions. The A. californica MNPV is being considered for commercial use as a pesticide in the United States, and the cloning of the virus, in view of the heterogeneity detected, may be advisable. The cloning and genotype analyses are also significant with regard to understanding the genetic nature of multiply embedded NPVs (those NPVs containing more than one nucleocapsid per envelope in the occluded form of the virus) and indicate that further genetic analysis of these viruses is possible.
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PMID:Isolation of genotypic variants of Autographa californica nuclear polyhedrosis virus. 35 31

We have developed a simple method based on cotransfection of overlapping DNA restriction fragments for construction of recombinants of adenovirus type 2 (Ad2) and Ad5. When Ad2 DNA digested with restriction endonuclease EcoRI was cotransfected with Ad5 DNA digested with SalI, recombination occurred between Ad2 EcoRI-A (map position 0 to 59) and Ad5 SalI-A (map position 45 to 100). Analysis of the recombinant DNAs by digestion with EcoRI or BamHI restriction endonucleases indicated that, as expected, recombination had occurred in overlapping sequences (map position 45 to 59) between the Ad2 EcoRI-A fragment and the Ad5 SalI-A fragment. By using this method, several recombinants were constructed between a large-plaque (lp) mutant of Ad2 and wild-type Ad5. Cleavage of the recombinant genomes with restriction endonucleases BamHI, EcoRI, and HindIII revealed that the lp mutation is located within the left 41% of Ad2 genome.
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PMID:Physical mapping of a large-plaque mutation of adenovirus type 2. 50 3

Adenovirus type 5 DNA has low infectivity (Graham & van der Eb, 1973) which can be increased by various techniques, one of which is the dimethyl sulphoxide (DMSO) boost (Stow & Wilkie, 1976). In this report, it is shown that DMSO treatment of adenovirus 5 DNA-infected HeLa cells results in a 10-fold increase in plaque formation, and that this can be used to facilitate marker rescue experiments. Double DNA infections were performed by the calcium phosphate method, co-precipitating intact temperature-sensitive mutant DNA with purified wild-type DNA restriction endonuclease fragments. Analysis of the plaquing ability of these mixtures and any progeny virus has resulted in the assignment of six temperature-sensitive mutations to discrete physical locations on the adenovirus type 5 genome. These locations are discussed with respect to the mutant phenotypes and the transcription-translation products of the appropriate regions.
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PMID:Mapping of adenovirus type 5 temperature-sensitive mutations by marker rescue in enhanced double DNA infections. 74 9

The physical state of the viral genome in four lines of hamster cells transformed by adenovirus type 12 (Ad12) has been investigated. The four lines of transformed cells originated from hamster cells after infection with Ad12 at multiplicities ranging from 5-350 plaque-forming units per cell. The DNA from transformed cells has been restricted with the Sal I endonuclease from Streptomyces albus which cleaves adenovirus DNA more frequently than DNA from adenovirus-transformed hamster cells. Thus after cleavage by the Sal I enzyme, it is possible to separate free adenovirus DNA sequences from these which are covalently linked to cellular DNA in transformed hamster cells. The results of sequential hybridization experiments in which the Sal I-treated DNA from transformed cells is first annealed to Ad12 DNA on filters, then eluted, and finally hybridized to hamster cell DNA, support the model of Ad12 DNA integrated in multiple fragments into the host genome. Further experiments will be required to characterize the host sequences adjacent to adenovirus DNA and to compare these sequences in different lines of Ad12 transformed cells.
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PMID:Integrated viral sequences in adenovirus type 12-transformed hamster cells. 83 40

UV-endonuclease from Microcossuc luteus induces single-stranded breaks in UV-irradiated DNA of phage lambda and the average length of the fragments produced (after UV-doses to DNA of 135 and 675 erg/mm2) is equal to the average spacing between pyrimidine dimers. The plaque-forming ability of UV-irradiated lambda DNA used to infect Ca++-treated uvr A6, uvrB5 or uvrC34 recipient Escherichia coli cells (but not uve+ cells) may be significantly enhanced by treatment of lambda DNA with UV-endonuclease. This enzyme strongly decreases the reactivation of UV-irradiated lambda DNA caused by UV-irradiation of uvr+ or uvrA6 Ca++-treated cells and eliminates most clear-mutations especially if mutations are analysed using Ca++-treated uvr A6 recipient cells. It is concluded that UV-endonuclease switches a significant part of potentially mutagenic pyrimidine dimers from the UV-induced "error-prone" repair pathway to "error-free" excision repair pathway.
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PMID:Ultraviolet reactivation and ultraviolet mutagenesis of infectious lambda DNA: strong inhibition by treatment of DNA in vitro with UV-endonuclease from Micrococcus luteus. 109 9

The abundance of repetitive DNA in the haploid sea cucumber genome has been determined by screening a Holothuria genomic DNA library for clones containing repeated sequences using reverse genome hybridization. Analysis by in situ plaque hybridization of a set of 1132 clones has revealed the presence of repetitive DNA sequences in about 38.1% of the clones screened. The distribution of the reiterated DNA has been further analyzed by restriction endonuclease digestion of seven randomly selected repetitive clones. The repeated sequences have a fairly uniform distribution of lengths with an average length value of 7.3 kb. Analysis of the measurements suggests that the repetitive sequences are interspersed among longer single copy sequences with an average spacing interval of about 47.3 kb indicating that the repetitive and single copy DNA in the Holothuria genome are arranged in a long-period interspersion pattern.
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PMID:Organization of repetitive DNA sequences in the genome of the echinoderm Holothuria tubulosa. 129 14

Recombinant DNA techniques were used to insert foreign genes into bovine herpesvirus-1 [infectious bovine rhinotracheitis virus (IBRV)] vectors which were attenuated by deletion and/or insertion mutations in the IBRV thymidine kinase (tk) gene. In one recombinant, the regulatory and coding sequences of the late pseudorabies virus (PRV) glycoprotein gIII gene, were inserted into the early IBRV tk gene. This recombinant efficiently expressed the PRV gIII gene indicating that immediate early IBRV proteins were competent to transactivate the late PRV gIII gene. IBRV vector viruses were also prepared in which the coding sequences of the early PRV tk gene, the late PRV gIII gene, and the E. coli beta-galactosidase gene were ligated to the late IBRV gIII promoter. Genotypes and phenotypes of the recombinant viruses were verified by restriction endonuclease and molecular hybridization experiments, thymidine plaque autoradiography, beta-gal plaque assays, and by immunoprecipitation experiments on extracts from 3H-mannose-labelled cells. The recombinant IBRV expressing beta-gal from the IBRV gIII promoter has been useful as an intermediate in the construction of IBRV vectors harboring foreign DNA sequences. The infectivity of the IBRV recombinant that expressed PRV gIII from the IBRV gIII promoter, was neutralized by polyclonal PRV antisera and by monoclonal antibodies to PRV gIII. The PRV gIII glycoprotein synthesized by the preceding recombinant has been used to coat microtiter test plate wells in a PRV gIII differential diagnostic test kit.
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PMID:Expression of porcine pseudorabies virus genes by a bovine herpesvirus-1 (infectious bovine rhinotracheitis virus) vector. 131 33

Twenty four cloned isolates of Aujeszky's disease virus collected from outbreaks of Aujeszky's disease from 1981 through 1989 in Japan were characterized by their restriction endonuclease (RE) cleavage patterns, virulence for mice and thymidine kinase (TK) activity. All of the isolates belonged to Type II of the four types classified by Herrmann et al. (1984). Based on the number and migration rate of the restriction fragments, the isolates were divided into 7 groups with Bam HI, 9 groups with Kpn I, 3 groups with BstE II and 2 groups with Sal I. The results indicate that the RE analysis, especially with Bam HI and Kpn I, provides useful epidemiological information about field isolates of Aujeszky's disease virus. All of the isolates showed virulence for mice ranging from 6.9 to 63.0 (PFU/LD50). It was interesting that the Nagano S87 strain, which had the highest virulence for the mouse, showed unique RE cleavage patterns with four enzymes. On the other hand, ara-T-resistant, TK-negative strain, was avirulent for mice (greater than 10(6.4) PFU/LD50). All of the isolates investigated in this study showed TK activity by the thymidine plaque autoradiography.
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PMID:Characterization of Japanese isolates of Aujeszky's disease virus by restriction endonuclease cleavage patterns, virulence in mice and thymidine kinase activity. 132 16

In genotypic mutation analysis DNA sequence changes are determined without the in vivo or in vitro selection of phenotypically altered cells. We have studied the induction of base-pair changes by N-ethyl-N-nitrosourea in Taq I endonuclease recognition site 2508-2511 (TCGA) of the c-H-ras1 gene in human fibroblasts by the restriction fragment length polymorphism/polymerase chain reaction (RFLP/PCR) method. This site contains the four bases, and all 12 possible single base-pair changes can be monitored. The transition of guanine to adenine at position 2510 was the major mutation detected by lambda plaque oligonucleotide hybridization and quantitative sequence analysis of the RFLP/PCR products. It involves the G residue of the CpG sequence of the coding strand. Data calibration with an internal mutant standard indicates that absolute frequencies for this transition lie in the range of 4-12 x 10(-7). The present study documents the capacity of the RFLP/PCR approach to measure mutagen-induced base-pair changes in a specific gene sequence without the selection of a phenotypically altered cell.
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PMID:Genotypic analysis of N-ethyl-N-nitrosourea-induced mutations by Taq I restriction fragment length polymorphism/polymerase chain reaction in the c-H-ras1 gene. 135 80

The reactivities of methyl isocyanate (MIC) and phenyl isocyanate (PIC) with DNA, and the genotoxicity of MIC were investigated. MIC and PIC reacted with the exocyclic amino group of deoxycytidine, deoxyadenosine and deoxyguanosine to produce carbamoylated products. The reactions of both isocyanates with deoxycytidine were 2 and 4 orders of magnitude higher than with deoxyadenosine and deoxyguanosine, respectively. To explore the genotoxicity of MIC, M13mp9 RF DNA was modified with MIC and then introduced into E. coli. The plaque-forming efficiencies of DNA decreased with increasing dose levels, and the decreases were more pronounced in Uvr endonuclease-deficient strains (uvrA, uvrB and uvrC) than in the Uvr endonuclease-proficient strain, JM103. The differences in survival in JM103 and uvr- strains suggest that the methylcarbonyl adducts can be removed by the uvr excision-repair system. Modification of M13mp9 RF DNA with MIC induced MIC-dose-related, SOS-dependent mutations in the beta-galactosidase locus. These results demonstrate the genotoxic response of MIC-modified DNA in E. coli.
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PMID:Selective reactivities of isocyanates towards DNA bases and genotoxicity of methylcarbamoylation of DNA. 138 95


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