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:3.1.21.1 (DNase)
7,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The chromatin structure of a diploid precursor B-cell line (REH), in vitro-stimulated normal B-lymphocytes, and reactive and malignant lymph node B-lymphocytes was studied by staining formaldehyde-fixed, permeabilized cells with the DNA-specific fluorophore 7-aminoactinomycin D (7-AMD) and measuring single-cell fluorescence by flow cytometry. Resting peripheral blood B- and T-lymphocytes (G0 cells) bound low amounts of 7-AMD (7-AMD- phenotype), while G1 REH cells and purified B-cells stimulated with anti-mu + B-cell growth factor bound nearly twice as much 7-AMD (7-AMD+ phenotype). 7-AMD binding increased up to threefold and the differences in binding between G0 and G1 cells were nearly abolished when nuclei were isolated prior to fixation or when fixed whole cells were treated with DNase 1. 7-AMD binding increased in parallel with autofluorescence and approximately linearly with time during the G0-G1 transition of in vitro stimulated B-cells, as was determined by simultaneous measurements of 7-AMD fluorescence and autofluorescence or fluorescence of fluorescein isothiocyanate-labeled antibodies to the early activation antigen 4F2 and to the transferrin receptor. In cell suspensions from lymph node biopsies, the 7-AMD+ phenotype was a property of tumor cells in patients with high grade non-Hodgkin's lymphoma (H-NHL, Kiel classification, 5/5); cells with this phenotype were only found in one of nine low grade non-Hodgkin's lymphoma samples (L-NHL, 1/9). The other (8/9) L-NHL samples and the reactive lymph node contained only 7-AMD- cells. All tumors were diploid. The correlation observed between 7-AMD binding and DNase 1 susceptibility of DNA in chromatin (P less than 0.001) suggests that 7-AMD binding is a marker of general transcriptional activity. Surprisingly, the percentage of tumor cells in S phase did not correlate significantly with 7-AMD stainability (P = 0.07), while the light scattering (cell size) of G0/G1 cells was highly correlated to 7-AMD binding (P less than 0.001).
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PMID:In vitro and in vivo activation of B-lymphocytes: a flow cytometric study of chromatin structure employing 7-aminoactinomycin D. 326 91

Membrane vesicles isolated from competent cultures of Bacillus subtilis 168 bound up to 20 mug of double-stranded deoxyribonucleic acid (DNA) per mg of membrane protein in the presence of ethylenediaminetetraacetate. The formation of the DNA-membrane complex was time, temperature, and pH dependent. Eighty per cent of the DNA could be removed from the complex by treatment with deoxyribonuclease I. Nevertheless, the DNA that remained attached to the vesicles appeared to have been attacked by the enzyme, suggesting that all the complexed DNA is located at the outer surface of the vesicles. Pretreatment of DNA with deoxyribonuclease I destroyed its affinity for the vesicles. The extent of binding decreased by the addition of Mg(2+) ions, especially at high DNA concentrations (more than 2 mug/ml). This effect was partially due to membrane-associated Mg(2+)-dependent endonucleolytic activity, which caused double-strand breaks in addition to single-strand nicks, and to exonuclease activity. The endonucleolytic activity was enhanced by heating the membranes at 80 C. DNA-membrane association was not markedly affected by sulfhydryl reagents, but was largely inhibited by formaldehyde. Endogenous competence-stimulating activity did not alter the DNA-binding capacity of the vesicles.
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PMID:Interactions between exogenous deoxyribonucleic acid and membrane vesicles isolated from Bacillus subtilis 168. 421

Aldehyde-fixed rat tissues were variously dehydrated and impregnated in water-miscible 2-hydroxypropyl methacrylate (HPMA) containing 3 to 20 per cent water and 0.1 per cent alpha,alpha-azobisisobutyronitrile as catalyst for subsequent polymerization with ultraviolet light. Heat polymerization was also effective. Blocks of embedded tissue readily gave ultrathin sections, which required staining by uranyl acetate and/or lead stains to give adequate contrast for electron microscopy. The ultrastructure of pancreas, kidney, muscle, and intestine was well preserved by aldehyde fixation alone. Use of postfixation in osmium tetroxide or direct osmium tetroxide fixation was unsatisfactory. The fine structure of aldehyde-fixed liver from fasted rats was well preserved, whereas that from normal rats showed considerable disorganization and collapse, apparently because of extraction of glycogen during the embedding procedure. Enzymatic extraction of proteins by pepsin and of ribonucleic acid by ribonuclease after either formaldehyde or glutaraldehyde fixation was rapidly effected by direct treatment of ultrathin sections with solutions of the enzymes. In contrast, no digestion of chromatin by deoxyribonuclease could be detected. In spite of this present limitation, HPMA appears to have several advantages over earlier water-miscible embedding media for electron microscopy and to be particularly suitable for ultrastructural cytochemistry.
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PMID:Hydroxypropyl methacrylate, a new water-miscible embedding medium for electron microscopy. 585 16

Randall, Charles C. (University of Mississippi, Jackson), Lanelle G. Gafford, Richard L. Soehner, and James M. Hyde. Physicochemical properties of fowlpox virus deoxyribonucleic acid and its anomalous infectious behavior. J. Bacteriol. 91:95-100. 1966.-Deoxyribonucleic acid (DNA) was extracted from fowlpox virus-infected tissue, purified inclusions, and purified virus by five variations of detergent and phenol methods. Phenol methods gave a poor yield, whereas detergent techniques extracted up to 78% of the DNA. The buoyant density was 1.695 g/ml, and the melting temperature in 7.2 m NaClO(4) was 39 C, both approximately equivalent to a guanine plus cytosine content of 35 moles per cent. Further proof of the double-stranded nature of the DNA was shown by the characteristic behavior toward deoxyribonuclease, formaldehyde, and heat. Infectious DNA was obtained by the various methods described, but this manifestation of biological activity was capricious and for unknown reasons was often not evident. The infectivity could not be related quantitatively to the amount of DNA employed. Furthermore, the infectious nature of fowlpox virus DNA was demonstrable only when the route of infection was the chorioallantoic membrane. In contrast, whole virus infected both membrane and chick skin with equal efficiency.
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PMID:Physicochemical properties of fowlpox virus deoxyribonucleic acid and its anomalous infectious behavior. 590 15

The interphase nucleolus in Allium porrum, as in many of the plant species studied so far, is highly heterogeneous in ultrastructure owing to the presence of coarse, contorted, thread-like structures, or nucleolonemata. Each nucleolonema appears to be sharply twisted and to give rise to a skein within the nucleolar mass. In order to characterize further these nucleolar components, a variety of cytochemical techniques were exploited. For that purpose, specimens were mostly fixed in 4% formaldehyde and stained in the block according to procedures known to reveal the presence of nucleic acids or proteins. Certain specimens were also digested with deoxyribonuclease, ribonuclease or proteinase K before staining. By staining with phosphotungstic acid or bismuth oxynitrate, the presence of a high concentration of proteins can be demonstrated within thin (0.15 micrometer), filamentous structures which are believed to correspond to the outer region of the nucleolonema. Such convoluted formations disappear upon sufficiently long extraction with proteinase K. Using Bernhard's regressive staining technique for chromatin, the distribution of this substance throughout the nucleolar mass was found to match closely that of the nucleolonemata as revealed by several other procedures. As a last test for investigating the cytochemical make-up of the nucleolus, blocks of tissues were stained with 3,3'-diaminobenzidine, a substance known to react specifically with nucleic acids. When such specimens are digested with ribonuclease for 1 h, there persist within the nucleolus, fibrillogranular zones the localization of which is highly reminiscent of that of the nucleolonemata. Combination of ribonuclease hydrolysis with subsequent treatment with proteinase K (30 min) induces the extraction of a large proportion of the nucleolar material, the persisting loose and rather evenly distributed fibrils exhibiting a diamter of 3-5 nm. The possibility is considered that these units may correspond to chromatin fibrils although they have most likely been displaced from their original localization during the extraction procedures. Our cytochemical data suggest that, in Allium porrum, the nucleolonema is approximately 0.3 micrometer in diameter and may consist of a central axis from which chromatin loops project radially. A possible interpretation for the presence of protein-rich, 0.1 micrometer-thick, annular structures throughout the nucleolonemal skein is that the newly synthesized RNP products are accumulated transiently at the extremities of these loops before migrating to the immediately adjacent granular nucleolar zones.
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PMID:An ultracytochemical study of nucleolar organization in meristematic plant cells (Allium porrum). 615 22

Rat liver and hepatoma cells fixed with formaldehyde, embedded into Epon and treated on sections with 5 n HCl and then with aqueous uranylacetate show preferential DNase-sensitive reaction. The reaction is highly dependent upon proper fixation, hydrolysis improves its specificity. The binding of the contrast with DNA is of ionic nature. Because of its simplicity, sufficient contrast and resolution the suggested technique is recommended for ultrastructural studies of DNA-containing substrates.
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PMID:Staining of DNA with uranylacetate in hydrolysed ultrathin sections. 616 27

Linear simian virus 40 DNA has been transcribed in vitro with wheat germ RNA polymerase II. Transcription products have been fractionated on polyacrylamide gels and several discrete sized RNA bands are seen. The RNA band pattern is affected dramatically by deoxyribonuclease treatment during RNA isolation. This is because most of the RNA synthesized is covalently linked to DNA. This linkage has been demonstrated by density analysis in formaldehyde-CsCl gradients and by incorporation of alkali-stable ribonucleotides into DNA. The linear DNA templates transcribed were generated by treatment of circular DNA with restriction enzymes which, in addition to cutting once at a single primary site, were found also to produce single strand nicks at specific secondary sites. The discrete sized RNA bands observed result from initiation at these nicks and terminated at DNA ends. There are two modes of nick-dependent initiation. In one mode the 3'-hydroxyl terminus of the DNA at a single strand nick serves as a primer for the extension of an RNA chain. In a second mode de novo initiation of an RNA chain is promoted at the nick. RNAs which are not primed initiate predominantly with GTP. The catalytic action of wheat germ RNA polymerase II is similar to that of Escherichia coli core RNA polymerase which has also been shown to synthesize primarily RNA which is covalently linked to DNA.
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PMID:Transcription of simian virus 40 DNA by wheat germ RNA polymerase II. Priming of RNA synthesis by the 3'-hydroxyl of DNA at single strand nicks. 624 89

An outbreak of horizontally transmitted malignant lymphoma in an experimental hamster holding facility was previously reported. Retroviridae (oncornavirus) or other conventional oncogenic viruses (oncodnaviruses) could not be detected in these lymphomas by immunological methods, direct isolation procedures or electron microscopy but an infectious agents was clearly involved. The incidence of lymphomas during five recurrent epidemics ranged from 50 to 90% in young, inbred and random-bred Syrian golden hamster exposed. The agent seemed to be resistant to UV inactivation, formaldehyde vapour and other viricidal agents (chlorine and iodine), and stable for long periods in the absence of hamster hosts in the contaminated facility. Associated disease syndromes in exposed hamster included severe enteritis, pyelonephritis, the occasional appearance of warts, poor breeding efficiency and intussusception. We now report the successful, cell-free isolation of an unusual, filterable agent prepared in protamine sulphate buffer from primary and animal-passaged lymphomas, which produces lymphomas with good efficiency when injected subcutaneously (s.c.) into newborn Syrian inbred (LSH) and random-bred (LVG) hamster. The agent could be reisolated from these induced lymphomas and injected into other hamsters to reproduce the neoplastic condition. It showed characteristics suggested for a mammalian viroid (a non-encapsidated, DNase-sensitive low-molecular-weight, disease-causing, self-replicating, naturally infectious nucleic acid).
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PMID:Unusual filterable oncogenic agent isolated from horizontally transmitted Syrian hamster lymphomas. 720 28

To evaluate reliable methods for detection of hepatitis C virus (HCV) infection in routinely processed liver biopsies we analyzed formaldehyde-fixed and paraffin-embedded liver specimens of 10 patients with serological confirmed HCV infection. We compared (1) conventional histology; (2) indirect immunofluorescence using the mAb TORDJI-22 (Clonatec, Paris, France); (3) RT-PCR using total RNA and Southern blotting with chemiluminescent detection; (4) non-radioactive in-situ hybridization (ISH) with digoxigenin-labeled oligo- and cRNA probes; (5) direct in-situ RT-PCR with incorporation of labeled nucleotides into PCR-products, and (6) indirect in-situ RT-PCR using subsequent ISH for the visualization of intracellular PCR-products. Our results indicate that: (1) using the histological criteria described by Lefkowitch et al. [Gastroenerology 1993;104:595] together with clinical data, most chronic HCV infections can be diagnosed by conventional histology, if liver biopsies specimens are adequate; (2) the commercially available mAb TORDJI-22 appears to crossreact with non-HCV epitopes, resulting in false positives; (3) molecular methods performed on routinely fixed and processed liver biopsies frequently yield false negative results due to sampling problems, low viral copy number and RNA degradation in infected cells; (4) analysis of HCV-RNA by RT-PCR of extracted total RNA is more sensitive than indirect in-situ RT-PCR or ISH; and (5) direct in-situ RT-PCR is not reliable despite the use of modifications such as DNase pretreatment and hot-start procedures. It is concluded, that several molecular methods for HCV detection must await further improvements of protocols to be suitable for routine diagnostics on paraffin-embedded liver biopsies.
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PMID:Evaluation of methods for hepatitis C virus detection in archival liver biopsies. Comparison of histology, immunohistochemistry, in-situ hybridization, reverse transcriptase polymerase chain reaction (RT-PCR) and in-situ RT-PCR. 753 15

With the availability of direct genomic footprinting techniques the study of native genomes has been greatly facilitated. This review provides an overview of the techniques involved and gives also a description of the mode of action of different DNA modifying agents which can be used for such methods. These include exonuclease III, deoxyribonuclease, DNase I, micrococcal nuclease, dimethyl sulfate, diethyl sulfate, ethyl methanesulphonate, ethylnitrosourea, diethylpyrocarbonate, bromoacetaldehyde, potassium permanganate, osmium tetroxide, methidiumpropyl-EDTA-iron(II), formaldehyde, psoralen, 1,10 phenanthroline-copper and UV light. We also describe the limitations of the currently existing techniques and give some potential developments.
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PMID:Approaches to characterize protein-DNA interactions in vivo. 843 8


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