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)

Small polydisperse circular DNA (spcDNA) isolated from the BSC-1 line of African Green monkey kidney cells was digested with the restriction endonuclease BamHI and cloned in bacteriophage lambda. The resulting library of 25,000 phage was then screened for the presence of the Alu family of short interspersed nucleotide sequences, and four of the 100 Alu-positive clones were characterized. In summary: (1) all four clones contained regions other than Alu that were homologous to the BSC-1 chromosome. Two contained Alu plus unique chromosomal DNA, one contained Alu plus an uncharacterized repetitive chromosomal DNA, and one contained Alu plus both unique and a specific tandemly repeated chromosomal DNA (alpha-satellite); (2) all four clones were derived from extrachromosomal circular DNAs and not from the accidental cloning of a very small amount of contaminating chromosomal material assumed to be present in spcDNA preparations; and (3) one clone represented an intact circular DNA with a restriction endonuclease cleavage map that was a circularly permuted version of its chromosomal homologue.
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PMID:Structure of extrachromosomal circular DNAs containing both the Alu family of dispersed repetitive sequences and other regions of chromosomal DNA. 632 8

A case of progressive multifocal leukoencephalopathy (PML) reported previously to be of simian virus (SV40) etiology was re-evaluated. The supernatant from a 10% homogenate of brain material was inoculated into African green monkey kidney cells and BSC-1 cells which are permissive for SV40. However no cytopathic effect (CPE) developed and no virus was isolated. The brain supernatant agglutinated human group O erythrocytes and contained 5120 units/mL. The Hirt supernatant from the brain contained three DNA bands corresponding to forms I, II and III of circular double-stranded viral DNA. Restriction endonuclease cleavage analysis revealed that this viral DNA was different from SV40 DNA, but similar to JC virus DNA. After cloning of this viral DNA into pBR322 at the BamHI site, DNA homology of this virus and of SV40 was investigated. Cloned DNA from the brain hybridized with all the HpaI/EcoRI fragments of the SV40 genome at the effective temperature of Tm -50 degrees C [corrected]. At Tm -28 degrees C, however, the cloned DNA hybridized with only HpaI/EcoRI fragment B of the SV40 genome. In contrast to this, JC virus DNA hybridized with all five EcoRI/BamHI/HindIII fragments of cloned DNA even at Tm -28 degrees C. Therefore, the causative agent of this PML case was not SV40 but JC virus.
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PMID:Re-evaluation of a case of progressive multifocal leukoencephalopathy previously diagnosed as simian virus 40 (SV40) etiology. 839 43

Archetype SV40, obtained directly from its natural host, is characterized by a single 72-bp enhancer element. In contrast, SV40 grown in cell culture almost invariably exhibits partial or complete duplication of the enhancer region. This distinction has been considered important in studies of human tumor material, since SV40-associated tumor isolates have been described having a single enhancer region, suggesting natural infection as opposed to possible contamination by laboratory strains of virus. However, the behavior of archetypal SV40 in cultured cells has never been methodically studied. In this study we reengineered nonarchetypal 776-SV40 to contain a single 72-bp enhancer region and used this reengineered archetypal DNA to transfect a number of simian and human cell lines. SV40 DNA recovered from these cells was analyzed by restriction endonuclease analysis, PCR, and DNA sequencing. Reengineered archetype SV40 propagated in green monkey TC-7 or BSC-1 kidney cells remained without enhancer region duplication even after extensive serial virus passage. Archetype SV40 grown in all but one of the rhesus or human cell lines initially appeared exclusively archetypal. However, when virus from these cell types was transferred to green monkey cells, variants with partial enhancer duplication appeared after as little as a single passage. These findings suggest (1) that virus with a single 72-bp enhancer may persist in cultured cells of simian and human origin; (2) that variants with partially duplicated enhancer regions may arise within cell lines in quantities below limits of detection; (3) that these variants may enjoy a selective advantage in cell types other than those from which they arose (e.g., green monkey kidney cells); and (4) that certain cell lines may support a selective growth advantage for the variants without supporting their formation. Our data indicate that enhancer duplication may also occur in human as well as rhesus kidney cells. Thus, detection of enhancer region duplication may not, a priori, indicate laboratory contamination, nor does detection of a single 72-bp enhancer exclude the possibility that contamination may have occurred. These findings may be of relevance to studies attempting to detect SV40 DNA in human tumors or other clinical specimens.
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PMID:The archetype enhancer of simian virus 40 DNA is duplicated during virus growth in human cells and rhesus monkey kidney cells but not in green monkey kidney cells. 1278 41


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