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)

Salmonella ordonez (BM 2000) codes for kanamycin (Km, aphA), ampicillin (Ap), streptomycin (SmSp:aadA and Sm:aphC), chloramphenicol (Cm), tetracycline (Tc) and sulfonamide (Su) resistances and for production of colicin Ib (Cib). Genetical analysis by incompatibility testing, conjugation, transformation and physical studies using electron microscopy, agarose gel electrophoresis, led us to associate the Km and Cib characters to a 98.7 kilobase (kb) IncI1 plasmid (pIP565), and the Sm (aphC) and Su determinants to a 8.3 kb plasmid (pIP605). The ApCmSmSp(aadA)SuTc determinants were not associated in BM2000 S. ordonez with a plasmid structure. Following conjugation of S. ordonez to E. coli, the ApCmSmSpSuTc determinants were found stably associated with a single plasmid structure (pIP173, 127.5 kb) belonging to IncI1 group. Agarose gel electrophoresis of plasmid DNA restriction endonuclease digests and electron microscopy heteroduplex analysis showed that the acquisition of the ApCmSmSpSuTc determinants resulted from the insertion into pIP565 of a 28.8 kb DNA sequence. This sequence coding for ApCmSmSpSuTu resistances in S. ordonez could be translocated either to pIP565 plasmid or to several IncI1 plasmids but never to plasmids belonging to IncW, IncP or IncFII, suggesting the existence of specific sequences on the IncI1 receptor plasmids. Moreover, R-determinants were translocated back "en bloc" from pIP173 to the chromosome of a susceptible S. ordanez. The results were consistent with the presence in BM2000 S. ordonez chromosomal DNA of an integrated translocatable sequence encoding ApCmSmSpSuTc resistances. Such a structural association could account for the stability of these resistances in the Salmonella ordonez serotype.
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PMID:Reversible translocation of antibiotic resistance determinants in Salmonella ordonez. 15 72

Comparative analysis of UV-sensitivity was carried out on plasmids of various molecular weight. Recombinant plasmids containing fragments of prokaryotic DNA (E. coli, phage lambda) are repaired in E. coli cells more effectively than those containing eukaryotic DNA fragments. It was also shown that UV-sensitivity of recombinant plasmids is independent of their molecular weight provided that the active repair process in fact occurs. UV-sensitivity was strongly proporational to DNA size only when E. coli double mutant strain was used as host. The survival of plasmids strongly increased after M. luteus UV-endonuclease treatment when E. coli mutant strain uvr- was used as host, but remained practically constant in case of wild type strain. Agarose gel electrophoresis data provide evidence that DNA double-stranded breaks appear un UV-irradiated as well as in UV-endonuclease treated plasmids. One can suggest that UV-inactivation of plasmids results from DNA breaking as a consequence of repair gaps overlap when wild type strain is used as host. Mathematical analysis was carried out assuming this possibility. Experimental data are shown to fit theoretical values calculated assuming that the repair gap size in one DNA strand is equal to 2000-3000 bases.
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PMID:[Repair of recombinant plasmids]. 39

Mitochondria were isolated and purified from paired lines of safflower (Carthamus tinctorius L.) restorer and cytoplasmic male sterile plants using isopycnic gradient centrifugation in isoosmotic Percoll. Agarose gel electrophoresis of restriction endonuclease digested DNAs showed characteristic polymorphism. Restriction fragments representing about 75% of the mitochondrial genome were common to both the fertile and CMS plants, but differed significantly in stoichiometric amounts. The remaining 25% could be accounted for by unique restriction fragments observed in only one or the other plant types.
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PMID:The mitochondrial genome of safflower: isolation and restriction fragment analysis of DNA from CMS and restorer lines. 167 56

Mitochondrial DNA (mt DNA) from a patulin producer, Penicillium urticae (synonym P. griseofulvum), was 27.8 kb +/- 0.6 kb in size by electron microscopy and 27.2 kb by agarose gel electrophoresis. Restriction endonuclease maps for nine restriction enzymes were constructed, and eleven fragments which covered the total range of the mt DNA were cloned into the Escherichia coli plasmid vector pUC19. Southern analysis of the native genomes of P. urticae and P. chrysogenum with six of the cloned fragments as probes indicated similar genome arrangements as well as similar restriction maps. Both the large and small rRNA genes of P. urticae and P. chrysogenum were located on these restriction maps using Southern hybridization, and the result also supported the similar arrangement. Agarose/formaldehyde gel electrophoresis indicated that the small rRNA was 1.5 kb in size in both species; but, surprisingly, the large rRNA was 4.2 kb in size for P. urticae and 3.5 kb for P. chrysogenum. These sizes were, respectively, 1.1 kb and 0.4 kb larger than those from the very closely related Aspergillus nidulans.
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PMID:Characterization and comparison of mitochondrial DNAs and rRNAs from Penicillium urticae and P. chrysogenum. 169 25

Hepatotoxic doses of acetaminophen cause widespread alkylation of liver and early loss of cytosolic Ca2+ regulation. Although the precise location and target of lethal alkylation are not known, Ca2+ accumulation is viewed as a possible link between cell alkylation and cell death. We have recently shown that Ca2+ accumulates in the nucleus and that DNA fragments in vivo before the development of acetaminophen-induced necrosis in mice. The present study examined cultured hepatocytes for nuclear damage and its association with cell death in vitro. Positive results would argue for two key points. (1) Nonparenchymal cell damage does not explain DNA fragmentation induced by acetaminophen in vivo. (2) A chemical that causes necrosis can produce DNA damage considered characteristic of apoptosis. Hepatocytes from NIH Swiss mice were isolated by collagenase perfusion, cultured in Williams' E medium for 24 hr, and exposed to acetaminophen. Cytotoxicity was assessed by lactate dehydrogenase leakage and release of [3H]adenine from a prelabeled nucleotide pool. Genomic DNA fragmentation was assessed quantitatively by colorimetric analysis and qualitatively by agarose gel electrophoresis. Acetaminophen caused DNA damage from 1-4 hr onward and produced significant release of lactate dehydrogenase and [3H]adenine nucleotides at later times. Agarose gel electrophoresis revealed a "ladder" of DNA fragments characteristic of Ca(2+)-mediated endonuclease activation. Cytotoxicity correlated with nuclear Ca2+ accumulation (r greater than 0.895, p less than 0.05) and with percentage DNA fragmentation (r greater than 0.835, p less than 0.05). Nuclear changes in vitro generally reproduced those observed in vivo. Collectively, these findings demonstrate that nuclear Ca2+ accumulation and DNA fragmentation appear as early events that correlate directly with later cytotoxicity. These changes may contribute to acetaminophen-induced injury leading to cell death in vitro and necrosis in vivo.
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PMID:Acetaminophen-induced cytotoxicity in cultured mouse hepatocytes: correlation of nuclear Ca2+ accumulation and early DNA fragmentation with cell death. 195 10

A rapid method for simultaneously banding preparative amounts of RNA and DNA from Trichinella spiralis muscle larvae by isopycnic centrifugation in cesium trifluoroacetate (CsTFA) is described. Larvae were homogenized in guanidinium isothiocyanate and the DNA, RNA, glycogen, and denatured protein components were isopycnically separated without prior purification. This procedure resulted in the isolation of nucleic acids suitable for molecular biological application. Agarose gel electrophoresis of gradient fractions indicated the separation of undegraded RNA and DNA where total RNA was of sufficient purity to efficiently direct in vitro translation of parasite protein and total DNA was greater than 20 kb in size and sensitive to restriction endonuclease digestion. Oligo (dT)-purified poly(A)+ mRNA was 3.6% of total RNA with greater than 18% conversion to cDNA.
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PMID:Simultaneous isolation of preparative amounts of RNA and DNA from Trichinella spiralis by cesium trifluoroacetate isopycnic centrifugation. 244 Mar 49

Two types of (CNBr-activated) Agarose-staphylococcal endonuclease derivatives have been prepared, one with the enzyme uniformly distributed in the support, and the other with the enzyme preferentially bound in the most external part of the support particles; the latter were obtained using agarose of very small pores and a high degree of activation. Quantitative enzyme distribution has been determined by scanning fluorescence microscopy. With these insoluble enzyme derivatives, a kinetic study for the hydrolysis of a mononucleotide has been carried out. A simple theoretical model for nonuniformly distributed insoluble enzyme derivatives, which considers only the case of mixed enzymic reaction-internal diffusion kinetics, is proposed. The experimental data agree very well with the predictions of the model.
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PMID:Mixed enzymic reaction--internal diffusion kinetics of nonuniformly distributed immobilized enzymes. The system agarose-micrococcal endonuclease. 303

The phage insensitivity of Streptococcus lactis KR5 was evaluated for its possible linkage to plasmid DNA. This strain possessed plasmids of 40, 29, 26, 21, 16.5, 10.5, 7.8, and 1.5 Mdal. Plasmid curing using novobiocin resulted in derivatives with increased sensitivity to prolate-headed phage, suggesting the involvement of plasmid DNA in phage insensitivity. Transformation of S. lactis LM0230 protoplasts with the KR5 plasmid DNA pool produced transformants containing a plasmid of about 27 Mdal. These erythromycin-resistant transformants were lactose-positive phage-sensitive or were lactose-negative and exhibited a reduced sensitivity to phage. Agarose gel electrophoresis and restriction endonuclease digestion analysis showed the 27-Mdal plasmid band to be composed of two distinct plasmids of 26 Mdal (pBF61) and 29 Mdal (pBF62), which coded for reduced phage sensitivity and lactose-positive phenotypes, respectively. The mechanisms of reduced phage sensitivity encoded by pBF61 included a restriction/modification system and a mechanism that resulted in reduced plaque size independent of incubation temperature. These results further support the involvement of plasmid DNA in the mechanisms for reduced phage sensitivity in dairy streptococci.
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PMID:Plasmid-mediated reduced phage sensitivity in Streptococcus lactis KR5. 313 85

The non-nitrogen-fixing (Nif-) strain UW10 of Azotobacter vinelandii OP (UW) was naturally induced to competence and transformed with broad host range plasmid pKT210 containing the cloned wild-type nif-10 locus from A. vinelandii UW (Nif+); this marker was unable to complement the nif-10 mutation in trans, but could through recombination with the chromosome. The most frequent type of transformation event observed was recombination between the homologous regions of the plasmid and chromosome (producing Nif+ transformants) with loss of the plasmid vector. At a substantially lower frequency, transformants expressing the plasmid-encoded antibiotic resistance determinants were isolated which were phenotypically Nif-. Agarose gel electrophoresis showed that these transformants contained a plasmid migrating with the same mobility as the original donor plasmid. During culture these transformants acquired a Nif+ phenotype without the loss of the plasmid, as judged by the use of a hybridization probe specific for the cloned nif-DNA fragment. These data indicate that plasmids carrying sequences homologous to chromosomal sequences could be maintained in recombination-proficient A. vinelandii UW. The introduction of plasmids containing sequences homologous to chromosomal sequences was facilitated by prelinearization of the plasmid using a restriction endonuclease generating cohesive ends. Because the site of linearization could be chosen outside the region of shared homology, it was unlikely that the route of plasmid establishment occurred via a homology-facilitated transformation mechanism. The data also indicated that A. vinelandii UW could harbor broad host range cloning vectors based on plasmid RSF1010 without significant impairment of its nitrogen-fixation ability.
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PMID:Transformation of Azotobacter vinelandii OP with a broad host range plasmid containing a cloned chromosomal nif-DNA marker. 323 89

Infection control teams rely on microbiology laboratories for accurate, reproducible data to trace the spread of microorganisms in the hospital. Since few problems are recognized immediately, laboratories should save important nosocomial pathogens so that outbreak strains will be available for analysis by more sophisticated techniques, particularly since automation has reduced the amount of epidemiologically useful data generated by routine procedures. Traditional supplemental reference procedures include phage typing, biotyping, serotyping and bacteriocin typing. Recently, analysis of antibiotic resistance determinants has provided the hospital epidemiologist with additional tools. Resistant strains have been characterized by their production of specific antibiotic inactivating enzymes. Agarose gel electrophoresis and restriction endonuclease analysis of plasmid DNA have permitted precise characterization of nosocomial strains, and the spread of antibiotic resistance genes can now be followed by sensitive and specific DNA probes. DNA probes also show promise for distinguishing nosocomial strains bearing known virulence factors from strains with less pathogenic potential. Molecular genetics techniques have found an additional role in elucidating the epidemiology of nosocomial viruses, especially the herpesviruses.
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PMID:New microbiological techniques for hospital epidemiology. 330 10


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