Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.25.1 (deoxyribonuclease)
 1,471 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The perichromatin granules were studied in hepatocytes of experimental rats injected with cycloheximide because the increased number of these nuclear components after such treatment facilitated their cytochemical investigation. Most perichromatin granules were sensitive to the digestion with pepsin and ribonuclease. In contrast, small population of perichromatin granules was resistent to such digestion under conditions which remove known RNA containing components such as ribosomes, nucleolar RNP components and interchromatin granules. The size of these resistent perichromatin granules was reduced and they consisted of filaments the width of which was similar to that of filaments in the chromatin. Moreover, a small population of perichromatin granules was sensitive to the digestion with pepsin and deoxyribonuclease. The size of these granules was only slightly reduced. All these observations indicate that most perichromatin granules contain the RNA and some the DNA. A possibility also exists that the perichromatin granules might contain both RNA and DNA but in various proportions. In addition, partial digestion with pepsin followed by a complete digestion with ribonuclease and deoxyribonuclease removed perichromatin granules as well as other nucleoprotein structures. On the other hand, such digestion facilitated the visualization of the nuclear and cytoplasmic skeleton (matrix) in situ.
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PMID:Further cytochemical studies on the perichromatin granules. 47 92

To establish the chemical composition of the arsenic inclusion, freshly isolated preparations of inclusions and epon-embedded thin sections of inclusions were subjected to ultrastructural cytochemical analysis. Intranuclear inclusions are composed of amorphous, arsenic-containing subunits aligned linearly to form a coiled complex. Lipase, ribonuclease, deoxyribonuclease, trypsin, pepsin, protease, amylase, or ethylenediaminetetraacetic acid (EDTA) was used to digest or chelate these inclusions. Following enzymatic digestion or chelation, the electron opacity of inclusions was compared with that of control sections exposed for equal times to equivalent solutions lacking the enzymes. Exposure to amylase caused a consistent reduction in the electron opacity of thin sections of inclusions and almost complete digestion of the freshly isolated preparations of inclusions. This was indicative of the presence of a carbohydrate moiety within arsenic inclusions. Incubation of inclusions with EDTA resulted in solubilization of freshly isolated and thin-sectioned embedded material. These data indicated that the intranuclear arsenic inclusion is composed of both metallic and carbohydrate moieties, confirming earlier studies which identified arsenic within inclusions using instrumental neutron activation analysis and X-ray microprobe analysis.
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PMID:Ultrastructural cytochemical analysis of intranuclear arsenic inclusions. 244 99

A protein was isolated from plasma of partially (70%) hepatectomized rats that, injected in mice, increases the uptake of [3H]thymidine by liver DNA by 200-300% over that by injected control saline. The purification procedure consists essentially of three chromatography steps, employing Sephadex G-75, DEAE-cellulose and hydroxyapatite. The hepatic promoter (HP) preparation shows a single band in SDS/polyacrylamide (15%)-gel electrophoresis (silver stained), with an Mr of 64 000; its activity is suppressed by trypsin or pepsin and is unaffected by deoxyribonuclease or ribonuclease. On injection into mice (150 ng/mouse), it increases the mitotic index of the liver. It shows organ-specificity, acting on liver but not on spleen, kidney, lung or brain. In primary liver cultures, it produces an increase in uptake of [3H]thymidine into DNA in the range 1-10 ng/ml. In this system in vitro, it increases the uptake of 22Na+ immediately after addition.
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PMID:Purification of a liver DNA-synthesis promoter from plasma of partially hepatectomized rats. 374 89

Cytological and cytochemical studies of green monkey kidney cells infected with SV40 virus indicated that the type of lesion produced was influenced by the multiplicity of infection and that the lesions appeared later and progressed more slowly when the inoculum was diluted. The earliest change consisted of enlargement of ribonucleoprotein-containing spherules in the nucleolus (nucleolini). This was followed by rarefaction, with or without condensation, of the chromatin and the appearance of one or more homogeneous masses of inclusion material containing DNA, RNA, and non-histone protein which eventually filled the nucleus. In some instances the chromatin appeared to be directly transformed into inclusion material. In the later stages of infection, the ribonucleoprotein of the nucleolini was no longer stainable and material resembling the nucleoprotein of the intranuclear inclusions was found in the nucleolar vacuoles and in the cytoplasm. The nucleic acids in the inclusions were stained by toluidine blue, toluidine blue-molybdate, the Feulgen stain, and by methyl green. The stainable material was extractable by nuclease digestion or by hot trichloroacetic acid. Green or yellowish green staining by acridine orange was apparently due to binding of dye by protein and not by nucleic acids since the staining reaction was not reduced by extraction of nucleic acids by hot trichloroacetic acid. Extraction with pepsin in combination with ribonuclease or deoxyribonuclease removed practically all the inclusions from the cells; consequently they could not be stained with acridine orange. The cytochemical studies suggest that the use of pepsin together with nuclease is not a meaningful technique.
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PMID:Cytological and cytochemical studies of green monkey kidney cells infected in vitro with simian virus 40. 428 71

The architecture of the nucleolus in Allium porum and Triticum vulgare meristematic cells has been investigated by means of digestions with various enzymes. After staining with azure B at pH4, plant nucleoli exhibit lighter regions which, under electron microscopy, correspond to the fibrillar zones characterizing these organelles. Evidence is presented indicating that these latter zones contain coarse convoluted filaments quite similar to the loops first demonstrated by La Cour (24) and which are assumed to originate from the nucleolar-organizing chromosomes. These coarse, 0.2micro wide filaments are remarkably resistant to the action of deoxyribonuclease, ribonuclease, pepsin, trypsin, or of various combinations of these enzymes and, moreover, they show insignificant incorporation of labeled thymidine even after long exposure to this DNA precursor. The clearing action of pepsin on different regions of the nucleolus lends support to the hypothesis that an amorphous material or matrix pervades the mass of this organelle. This effect is particularly striking within the particulate nucleolar zones themselves. Both ribonuclease and trypsin disorganize the RNP (ribonucleoprotein) nucleolar particles. The effect of the latter enzyme on the RNP particles is taken to indicate that they contain proteins particularly susceptible to trypsin which are essential for maintenance of their morphological integrity. Trypsin also interferes with azure B-staining of the nucleolar mass as a whole and, according to radioautographic data, extracts RNA throughout this organelle. Accordingly, the hypothesis is considered that RNA is complexed with proteins not only within the particulate nucleolar portions, as is already well known, but also in the fibrillar zones.
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PMID:The organization of the nucleolus in meristematic plant cells. A cytochemical study. 488 77

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

Compact nucleoli without the segregation of nucleolar components were produced in hepatocytes by the treatment of experimental rats with cycloheximide to facilitate a cytochemical study on the organization of nucleolar components in such nucleoli. The extraction of pepsin pretreated specimens with nucleases (deoxyribonuclease and ribonuclease) demonstrated that compact nucleoli are characterized by a relatively uniform distribution of RNP components which mask a microtrabecular intranucleolar network. This network apparently consists of proteins and contains fine DNA filaments.
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PMID:Cytochemistry of the microtrabecular network in compact nucleoli of hepatocytes treated with cycloheximide. 676

During purification of fungal deoxyribonuclease (DNase) from Syncephalastrum racemosum, a protein which was functionally unknown and persistently existed in the DNase-containing fractions through chromatography over DEAE-cellulose, hydroxylapatite, and phenyl-Sepharose was identified. The protein was finally separated from DNase after affinity chromatography on a cibacron blue-Sepharose column and purified to apparent homogeneity after gel chromatography on a Superdex 200 HR column. Ten tryptic peptides of this protein were isolated and sequenced. Searching in the sequence data bank with the aid of the computer program PC/Gene, we found that this protein was highly homologous to aspartic proteinases, such as pepsin and rhizopuspepsin. Because of its fungal origin and because the protein indeed showed catalytic cleavage on peptide bonds of bovine serum albumin, RNase, and carbonic anhydrase, we termed this protein syncephapepsin. The molecular weight of syncephapepsin is 38,000 daltons, based on gel filtration and sodium dodecyl sulfate-polyacrylamide electrophoresis.
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PMID:Identification of a fungal protein of Syncephalastrum racemosum as aspartic proteinase. 883 44

A method for the isolation of metaphase chromosomes from mouse L1210 leukemia cells has been developed. Cells, arrested at metaphase with colchicine, were exposed to hypotonic solution and the pH was then adjusted to 5.6 to stabilize the chromosomes. The metaphase figures were subsequently disrupted and the chromosomes isolated by a series of differential centrifugations in sucrose. The isolated chromosomes were well preserved, as judged by morphological criteria. The effect of various enzymes and chemical agents on the isolated chromosomes was studied. Chymotrypsin, trypsin, and deoxyribonuclease caused a marked disintegration of the chromosomes, whereas treatment with pepsin and ribonuclease induced no significant morphological alterations.
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PMID:STUDIES ON THE ISOLATION OF METAPHASE CHROMOSOMES. 1406 2

The effects of proteolytic enzymes, ribonuclease, and deoxyribonuclease upon a fibrous component of chick embryo mitochondria, which was previously shown to have many fixation and staining properties characteristic of the bacterial nucleoplasm, are reported. Pepsin digestion of formaldehyde-fixed tissues removed the membranes and matrices of mitochondria, but a pepsin-resistant fibrous material remained which was heavily stained by uranyl and lead ions. Experiments on a DNA "model system" showed that DNA treated with osmium tetroxide can be depolymerized by deoxyribonuclease. Zinc ions strongly inhibited the depolymerization of DNA. Digestion of osmium tetroxide-fixed tissues (fixed only briefly) with deoxyribonuclease for 1 hour greatly reduced the Feulgen staining of the nuclei, and after 4 hours the Feulgen reaction was completely abolished. The reduction and the disappearance of the Feulgen reaction in nuclei was paralleled by partial to complete digestion of the mitochondrial fibers in the regions studied (after 1 and 4 hours, respectively), without any other obvious changes in cellular structures. When deoxyribonuclease was inhibited by the addition of zinc ions, the nuclear Feulgen reaction was not diminished, nor were the mitochondrial fibers removed. Buffer control incubations for deoxyribonuclease and ribonuclease did not alter the structure or staining properties of the mitochondrial fibers, nor did incubation with ribonuclease. The latter reaction digested the cytoplasmic and nucleolar ribosomes after a 4-hour incubation period, in parallel with the abolishment of toluidine blue staining. The results contribute further evidence that these mitochondria contain deoxyribonucleic acid.
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PMID:INTRAMITOCHONDRIAL FIBERS WITH DNA CHARACTERISTICS. II. ENZYMATIC AND OTHER HYDROLYTIC TREATMENTS. 1408 39


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