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)

A new class of linear duplex DNA structures that contain simian virus 40 (SV40) DNA sequences and that are replicated during productive infection of cells with SV40 is described. These structures comprise up to 35% of the radioactively labeled DNA molecules that can be isolated by selective extraction. These molecules represent a unique size class corresponding to the length of an open SV40 DNA molecule (FO III), and they contain a heterogeneous population of DNA sequences either of host or of viral origin, as shown by restriction endonuclease analysis and nucleic acid hybridization. Part of the FO III DNA molecules contain viral-host DNA sequences covalently linked with each other. They start to replicate with the onset of SV40 superhelix replication 1 day after infection. Their rate of synthesis is most pronounced 3 days after infection when superhelix replication is already declining. Furthermore, they cannot be chased into other structures. At least a fraction of these molecules is infectious when administered together with DEAE-dextran to permissive cells. After intracellular circularization, superhelical DNA FO I with an aberrant cleavage pattern accumulates. In addition, tumor and viral capsid antigen are induced, and infectious viral progeny is obtained. Infection of cells with purified SV40 FO I DNA does not result in FO III DNA molecules in the infected cells or in the viral progeny. It is suggested, therefore, that these FO III DNA molecules are perpetuated within SV40 virus pools by encapsidation into pseudovirions.
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PMID:Infectious linear DNA sequences replicating in simian virus 40-infected cells. 18 87

A plaque-forming lambdapolA phage was isolated from a population of transducing phage made in vitro from Escherichia coli DNA and a phage vector digested with restriction endonuclease HindIII. Amber mutations, in genes whose products are necessary for late protein synthesis (Q) and cell lysis (S), were crossed into the lambdapolA phage. Infection of either polA+ or polA- bacteria with this phage, under conditions permitting DNA replication but preventing phage production and lysis, elevated the levels of DNA polymerase I to between 75- and 100-fold that detected in a wild-type strain. The kinetics of enzyme production suggest that the polA gene is transcribed from its own promoter rather than from any of the well-characterized phage promoters. The fragment of E. coli DNA within the lambdapolA phage comprises approximately 5000 base pairs, sufficient to accommodate the polA gene and one, or two, coding sequences for smaller proteins.
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PMID:Isolation and characterization of a lambdapolA transducing phage. 34 Nov 64

The nonrestricting/nonmodifying strain Bacillus subtilis 222 (r-m-) can be induced to synthesize a DNA-modifying activity upon treatment with either mitomycin C (MC) or UV light. This is shown by the following facts. (i) Infection of MC-pretreated 222 cells with unmodified SPP1 phage yields about 3% modified phage that are resistant to restriction in B. subtilis R (r+m+). The induced modifying activity causes the production of a small fraction of fully modified phage in a minority class of MC-treated host cells. (ii) The MC-pretreated host cells contain a DNA cytosine methylating activity: both bacterial and phage DNAs have elevated levels of 5-methylcytosine. (iii) The MC-induced methylation of SPP1 DNA takes place at the recognition nucleotide sequences of restriction endonuclease R from B. subtilis R. (iv) Crude extracts of MC-pretreated 222 cells have enhanced DNA methyltransferase activities, with a substrate specificity similar to that found in modification enzymes present in (constitutively) modifying strains.
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PMID:Restriction and modification in Bacillus subtilis: inducibility of a DNA methylating activity in nonmodifying cells. 82 59

Infections with Yersinia pseudotuberculosis serotype III and Y. enterocolitica serotype O2,3 were found to be common in Australian sheep flocks. Transmission of Y. pseudotuberculosis occurred in late winter and early spring, while Y. enterocolitica transmission occurred from midwinter to early summer. Excretion of Y. pseudotuberculosis was limited to the winter and spring period and was particularly common in 1- and 2-year-old sheep. Infection persisted for up to 14 weeks. Y. pseudotuberculosis infection did not confer immunity to natural infection with Y. enterocolitica. Y. enterocolitica excretion occurred year-round, with the greatest prevalence being in summer and autumn. Infection persisted for up to 29 weeks. Sheep less than 1 year old were most commonly infected with Y. enterocolitica. Infection with either Y. pseudotuberculosis or Y. enterocolitica was rare in aged sheep. Restriction endonuclease analysis of Y. pseudotuberculosis serotype III from sheep, cattle, deer, and pigs showed that the bacterial isolates were genetically indistinguishable. Similarly, Y. enterocolitica isolates from sheep were indistinguishable from those isolated from goats and cattle.
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PMID:Epidemiology of Yersinia pseudotuberculosis and Y. enterocolitica infections in sheep in Australia. 131 49

Human herpesvirus type 6 (HHV-6), a newly recognized human herpesvirus first described in 1986, is morphologically similar to other herpesviruses but is distinguishable from all of them by some unique in vitro biological effects, specific antigenic analysis, and patterns of endonuclease restriction digests of DNA. In vitro HHV-6 exhibits tropism mainly for T lymphocytes, but it also infects other cells, including B lymphocytes, monocytes-macrophages, glial cells, and fibroblasts. Because HHV-6 causes frequent infection in infants and children, a seroprevalence rate of antibody to this virus of up to 80% has been reported in the United States. Infection in infancy develops as levels of maternal antibody wane, thus resulting in either subclinical infection or an acute febrile illness termed exanthema subitum. Primary infection acquired later in life causes a disease resembling acute infectious mononucleosis. Since HHV-6 shares the capacity to establish latent infection with other herpesviruses, frequent viral reactivation is probably the explanation for the high incidence of serologically proven active HHV-6 infection found simultaneously with active infection due to other herpesviruses as well as in the presence of various immune deficiency conditions.
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PMID:Human herpesvirus type 6: review. 131 2

The major histocompatibility complex and prolactin (PRL) genes are syntenic in humans and cattle but the genetic distance between these loci has not been determined for either species. In this study, the sperm typing technique was used to measure the recombination frequency between the bovine lymphocyte antigen (BoLA)-DRB3 and PRL loci. A total of 300 sperm were typed from one doubly heterozygous bull for segregation of DRB3 and PRL alleles. Sperm typing was performed using the polymerase chain reaction (PCR) and restriction enzyme cleavage of the PCR products, followed by resolution of the restriction fragments in polyacrylamide gels. Digestion with the restriction endonuclease RsaI allowed the unambiguous discrimination of alleles for both loci. The maximum likelihood estimation of the recombination fraction theta = 0.04, with a 95% confidence interval of 0.01 to 0.07. Close linkage between PRL and DRB3 has important implications for marker-assisted selection in animal breeding since PRL has been shown to be closely linked to a locus that affects milk yield, and BoLA loci influence susceptibility to a number of infectious diseases. Our results demonstrate the general applicability of the sperm typing procedure for gene mapping in species other than humans and provide an example of how parallel efforts to map the genomes of agriculturally important species of animals can have a positive impact on the development of a primary human linkage map.
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PMID:Close linkage between bovine prolactin and BoLA-DRB3 genes: genetic mapping in cattle by single sperm typing. 157 92

To account for the wide variations in the prevalence of cytomegalovirus infections among day-care centers we serially tested 309 children at three day-care centers for 3 years. Based on the DNA restriction endonuclease pattern of each isolate, the rate of infection for children differed significantly (P less than 0.001) among centers: at Center 1, 50% (46 of 93) of children acquired cytomegalovirus in day care; at Center 2, 62% (64 of 104); and at Center 3, 25% (21 of 84). Infection rates were associated with the number of infants enrolled, and half or more of infected children were younger than 24 months of age. Six of 7 new isolates were introduced by children 18 months of age. Based on DNA patterns the prevalent isolates at Centers 1 and 2, although different, were shed for an average of 22 and 23 months, respectively, compared with an average of 15 months for other isolates (P less than 0.001). Reinfections with the prevalent isolates were observed for 2 of 34 children tested. The most important factors affecting day-care center transmission are the number of infants enrolled and prolonged viral shedding, possibly enhanced by reinfection.
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PMID:Molecular epidemiology of cytomegalovirus: a study of factors affecting transmission among children at three day-care centers. 165 38

The Oka varicella vaccine strain can be differentiated from wild-type strains by its unique restriction endonuclease fingerprinting (REFP: HpaI-K and EcoRI-P) pattern of the gpV-coding region of the varicella-zoster virus (VZV) genome. VZV-DNAs from patients with complicated clinical courses related to vaccination were examined to determine whether they were vaccine-derived or wild-type. A virus was isolated from a one year-old boy with acute lymphocytic leukemia (ALL) who developed typical varicella 28 days after vaccination (case A). Another virus was isolated from a four-year-old boy without clinical symptoms following household contact with varicella patients at the age of two months, and he developed zoster 14 months after vaccination (case B). Also, two strains (OK1 and OK2) were isolated from household contacts (mother and sister) with a vaccine with ALL in Oklahoma who developed varicella 18 days after vaccination (case C). In case C, BgII-REFP did not determine conclusively whether the two strains (OK1 and OK2) were vaccine-derived or wild-type because the patterns obtained were different from both the Oka varicella vaccine strain and American wild-type strains [Gelb et al., Journal of Infectious Diseases, 155:633-640, 1987]. All VZV strains examined in the present study were identified as wild-type by our method using HpaI-K and EcoRI-P fragments as marker fragments. Thus it is becoming evident that REFP using HpaI and EcoRI endonucleases is a convenient and reliable means of distinguishing between the Oka vaccine virus strain and wild-type viruses isolated from individuals developing vesicular rashes shortly and long after varicella vaccination.
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PMID:Differentiation of oka varicella vaccine strain from wild varicella-zoster virus strains isolated from vaccinees and household contact. 167 58

The denV gene from bacteriophage T4 encodes a pyrimidine dimer-specific endonuclease that has the capacity to initiate excision repair of DNA. Cells from excision repair-deficient xeroderma pigmentosum (XP) patients are able to carry out excision repair initiated by the denV gene product and introduction of the denV gene into XP cells results in the partial restoration of colony-forming ability after irradiation with UV light. In this work we have constructed a helper-independent recombinant human adenovirus, Ad5denV, which contains the denV gene. A 1.9 kb cartridge consisting of the denV gene flanked by the long terminal repeat (LTR) promoter from Rous sarcoma virus (RSV) and the simian virus 40 (SV40) polyadenylation (poly A) splice signals, was inserted into the E3 region of an E3 deletion mutant (Ad5d1E3) of adenovirus type 5. Infection of human fibroblasts and other permissive human cells with Ad5denV resulted in lytic infection and expression of the denV gene was confirmed by primer extension of infected cell RNA. The ability of the denV gene to restore the DNA repair deficiency in XP fibroblasts was examined using host cell reactivation of viral structural antigen formation for UV-irradiated adenovirus. The control virus, Ad5VSV, was also a recombinant which contained the gene for vesicular stomatitis virus glycoprotein G inserted into the E3 region of Ad5d1E3. UV survival of Ad5denV was similar to that of Ad5VSV following infection of two normal fibroblast strains and a Cockayne syndrome fibroblast strain, CS7SE, from complementation group B. In contrast, UV survival of Ad5denV was significantly greater than that for Ad5VSV after infection of three unrelated XP fibroblast strains from complementation groups A, C and E. However, UV survival of Ad5denV in the XP fibroblasts did not reach levels obtained in normal fibroblasts, indicating that restoration of the XP defect was partial.
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PMID:Construction of a recombinant adenovirus containing the denV gene from bacteriophage T4 which can partially restore the DNA repair deficiency in xeroderma pigmentosum fibroblasts. 170 21

The temperate bacteriophage phiLC3, isolated from Lactococcus lactis subsp. cremoris, has an isometric head and a flexible tail containing 1 major protein and 8 minor proteins. Infection of a permissive L. lactis host strain yields a burst of about 50 phages per infected cell with a latent period of 60 min. A detailed restriction map of the phage chromosome was constructed by using 12 different restriction enzymes. The phage chromosome is a 33-kb linear double-stranded DNA molecule with unique cohesive ends and with a G + C content of 36.5%. Chemical sequencing of the DNA ends revealed 13-base 3' extended complementary single strands with a relatively high percentage of G + C. Pulsed-field gel electrophoretic analysis of DNA from a strain lysogenized with phiLC3 was used to localize the prophage to a 320-kb BamHI restriction endonuclease fragment from the host chromosomal DNA. This result indicates that lysogeny involves integration of the phage into the host chromosome. A spontaneous phiLC3 clear plaque mutant that was unable to give rise to lysogens was isolated.
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PMID:Characterization of phiLC3, a Lactococcus lactis subsp. cremoris temperature bacteriophage with cohesive single-stranded DNA ends. 184 Apr 80


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