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Query: UMLS:C0009443 (cold)
 92,137 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Endogenous type C viruses have been detected in a wide variety of mammalian species. Multiple copies of related, but not identical, virogene sequences can be found in the DNA of these species. 2. The endogenous type C virogenes are subject to the pressures of natural selection, and closely related species possess related virogene sequences. These genes evolve as cellular entities diverging from one another in a manner which correlates well with taxonomic relatedness of the species. 3. The endogenous type C viruses of baboons and domestic cats are related, but they can be distinguished by biologic and immunologic criteria and by partial nucleic acid sequence homology. Virogene sequences in the DNA of Old World monkeys and domestic cats also show a degree of relatedness not shared by the unique sequence DNA of these species. The data suggest that progenitors of domestic cats were exogenously infected by a type C virus that also gave rise to present-day endogenous type C viruses of Old World monkeys. 4. The genomes of exogenously infectious viruses replicating in permissive host cells appear to evolve much more rapidly than endogenous virogenes which replicate as cellular genes. Laboratory strains of efficiently oncogenic type C viruses are presumed to be derived from activated endogenous viruses which have been selected for virulence and which, in certain cases, have acquired the capacity to replicate in the host's own cells. 5. The ubiquitous presence of endogenous type C viruses among vertegrates and their preservation throughout millions of years of evolution suggests that these genes express normal physiologic functions which provide a selective advantage to the species.
Cold Spring Harb Symp Quant Biol 1975
PMID:Endogenous primate and feline type C viruses. 5 Aug 95

We have investigated three aspects of RNA turmor virus replication and cell transformation: (1) the properties of the purified avian and mammalian viral RNA-directed DNA polumerase, (2) some characteristics of the viral 60-70S RNA genome, 30-40S RNA subunits and intracellular viral RNA species, and (3) the interaction of the viral DNA polymerase with its RNA template early during infection and cell transformation by the murine sarcoma-leukemia virus (MSV[MLV]). Avian myeloblastosis virus (AMV) contains two forms of RNA-directed DNA polymerase, alpha, consisting of a single polypeptide of molecular weight 65,000, and alphabeta, consisting of two polypeptides of molecular weights 65,000 and 105,000. The alpha and alphabeta forms of AMV DNA polymerase both possess RNase H activity that requires free end termini on the ribopolymer and can degrade the RNA of the RNA-DNA hybrid in the 3' to 5' and 5' to 3' directions. But, alpha and alphabeta possess a different mode of exoribonuclease activity. While alphabeta RNase H is a processive exoribonuclease that degrades the polynucleotide chain to a core residue before attacking a second chain, alpha RNase H is a random exoribonuclease that releases the polynucleotide after each scission. Highly purified Moloney-MSV(MLV) DNA polymerase has both RNase H activity and the ability to read viral 60-70S RNA. These activities comigrate through five different steps of purification and are present at levels comparable to those found in purified AMV DNA polymerase. The MSV(MLV) 60-70S RNA genome and 35S RNA subunits were shown by periodate oxidationtritiated borohydride reduction to contain adenosine as the major 3'-terminal nucleoside. Poly (A) segments were isolated from viral 60-70S and 35S RNA by treatment with RNase A or RNase T1 and purified by afinity chromatography and gel electrophoresis. Viral poly(A) was shown to be present at the 3' terminus as -G(C,U)A190AOH. The similar sequence reported for poly(A) present in mammalian mRNA suggests that similar mechanisma are involved in the transcription and processing of both cellular and viral DNA sequences. Within transformed cells replicating MSV(MLV), viral 35S and 20S RNA were found in membrane-bound polyribosomes, whereas only 35S RNA was detected in free polyribosomes. The origin and function of 20S RNA is unknown. The early events during rapid infection and cell transformation of mouse 3T6 cells by the Harvey strain of MSV(MLV) were studied. By both autoradiographic analysis and molecular hybridization, viral DNA synthesis was detected in the cytoplasm by 1 hour after infection, reached a maximum at 2 hours, and subsequently decreased. Cytological chase experiments produced evidence that cytoplasmic viral DNA was transported to the nucleus. In situ hybridization experiments using radioactive viral DNA product as a probe demonstrated the rapid association of viral DNA sequences with the chromocenters of interphase nuclei and with the centromeric heterochromatin regions of some chromosomes.
Cold Spring Harb Symp Quant Biol 1975
PMID:Properties of oncornavirus RNA-directed DNA polymerase, the RNA template, and the intracellular products formed early during infection and cell transformation. 5 Sep 2

We have reviewed our recent evidence for the following scheme for synthesis and integration of viral DAN after infection of permissive cells by ASV: Within the first 3 hours of infection, duplex, virus-specific DNA the length of a subunit of the viral genome (3 times 10(6) daltons) is synthesized in the cytoplasm of infected cells by a virion-associated DNA polymerase; viral DNA probably forms a covalently closed circular duplex prior to integration into host nuclear DNA. Integration and the usual consequences of viral infection can be inhibited by ethidium bromide. We have described a number of features of viral DNA prior to its integration and have indicated how these features can be exploited in the purification of viral DNA. Viral DNA has also been measured in nonpermissive (mammalian) cells in which the variable expression of viral genes is controlled by unknown mechanisms.
Cold Spring Harb Symp Quant Biol 1975
PMID:Synthesis, structure and function of avian sarcoma virus-specific DNA in permissive and nonpermissive cells. 5 Sep 3

This paper points out certain theoretical problems in DNA synthesis associated with antiprimer transcription and with circularization that could oblige RNA tumor viruses to rely on a polyploid genome. It is suggested that each completed act of reverse transcription may be coupled with an act of genetic recombination aimed at recovering the antiprimer information from an adjacent genome subunit in a polyploid train. A partially double-stranded DNA transcript could then be formed with sufficient terminal redundancy to permit circularization. The model provides satisfactory explanations for observed genetic interactions (particularly recombination and heterozygote formation), for inactivation data and for selective subunit transcription.
Cold Spring Harb Symp Quant Biol 1975
PMID:The genome of RNA tumor viruses: a functional requirement for a polyploid structure? 5 Sep 4

Metaphase chromosomes of the Chinese hamster differentially-condensed under the influence of a) 5-bromdeoxyuridine, b) colcemide, and c) cold, were stained with acridine-orange (AO) in concentrations of 1.5 X 10(-7) to 3 X 10(-5) g/ml at pH 4.1 to 8.5. It was found that stretched chromosomal segments fluoresced in the orange/red part of the spectrum, whereas normally condensed ones--were green. The colour distribution along the chromosome depended mainly on the AO concentration and the exposure in the UV-light, and was independent of pH and molarity of the buffer. Apparently this phenomenon cannot be attributed to the uneven denaturation of the chromosomal DNA, but rather depends on structural and/or chemical differences between euchromatin and heterochromatin.
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PMID:[2-colored fluorescence of differentially condensed chromosomes stained with acridine orange]. 5 76

A potent anti-idiotype serum produced in a rabbit immunized with the isolated heavy chains of an IgM cold agglutinin "Col" was rendered specific by solid-state adsorptions. The anit-Col idiotype was shown to bind specifically to both isolated Col heavy (mu) and light (kappa) chains as well as to intact Col IgM by three methods: (i) reversal of anti-idiotype inhibition of Col cold agglutinin in an automated hemagglutination-inhibition assay system; (ii) adsorption of the anti-idiotype by affinity gels consisting of Col IgM, mu, or kappa chains covalently coupled to Sepharose 2B; (iii) binding of Col IgM and its isolated chains by an anti-idiotype affinity gel. Fragments of Col light chain lacking constant region determinants but still capable of inhibiting anti-idiotype were produced by limited pepsin digestion of the light chains. The finding of shared idiotypic determinants on isolated heavy and light chains of a monoclonal antibody suggests that these chains share a common sequence in a hypervariable region. As an extension of the gene insertion theory of Wu and Kabat, we postulate that genes coding for hypervariable regions may be available for insertion into the DNA for both heavy and light chains.
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PMID:Demonstration of an idiotypic antigen on a monoclonal cold agglutinin and on its isolated heavy and light chains. 5 18

A combined Feulgen-alkaline fast green method is described for simultaneous demonstration of DNA and basic proteins in the cell nucleus. The method is based on preserving both types of substances in the tissue section and releasing in them reactive groups for the 2 kinds of staining. These conditions are best provided, as proved by staining tests on tissue hydrolysates, if formalin-containing mixtures (SERRA's or LILLIE's fluids) are employed for fixation, and cold 5 N HCl is used for FEULGEN hydrolysis. In this way, a good cytological picture is also achieved. Nuclear euchromatin stains with this method red, while heterochromatin, pycnotic nuclei and sperm heads exhibit a deep violet to blue-violet colour. Prominent nucleoli of metabolically active cells display a distinct blue-green staining thus manifesting their high content of basic proteins. Acetylation test reveals that these proteins are of lysine-rich type. The known negative reaction of the nucleoli with the routine alkaline fast green method according to ALFERT and GESCHWIND must be attributed to an extraction of the nucleolar basic proteins with the hot TCA used in this method. Certain analogy in the cytochemical behaviour between the nucleolous and the chromatin under various conditions of hydrolysis leads to the suggestion that the nucleolar basic proteins demonstrated should be in the form of a ribonucleoprotein complex, probably of the pre-ribosomal material of the nucleolus.
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PMID:On the cytochemical demonstration of basic proteins in the cell nucleus, including the nucleolus. 6 91

A cytochemical method is suggested for the simultaneous and differential staining of cellular nucleoproteids [ribonucleoproteids (RNP) and desoxyribonucleoproteids (DNP)], as well as for the simultaneous contrast staining of some basic (arginine- and lysin-containing) proteins. The staining technique is based on DNA-denaturation procedures and the application of mixtures of basic dye--methylene blue and acid dyes--eosin or fast green at low concentrations. The combination of methylene blue with eosin is used for the staining of ribonucleoproteids (RNP) whereas methylene blue-fast green for the simultaneous detection of ribonucleoproteids and desoxyribonucleoproteids (RNP and DNP), as well as for the differential staining of nuclear DNP (after cold hydrolysis with 5 N HCl). The acid dyes eosin and fast green stain in pink resp. in green some cathionic proteins in the lysosomal (specific) granules of the neutrophilic and eosinophilic leucocytes in the cytoplasm of erythrocytes, and after cold hydrolysis in the cytoplasm of lymphocytes. A fluorescent variant of the method with sulfaflavin is also suggested for the fluorochromation of cytoplasmic cathionic granules in the luecocytes. Acid mucopolysaccharide components in the granules of basophilic leucocytes, tissue mastocytes and thrombocyres are stained intensively pink-violet (gamma-metachromatic). The possibilities for the application of the method in the quantitative analysis of blood and exfoliated cells, as well as for purpose of haematology, immunology and exfoliative cytology are discussed.
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PMID:A cytological method for the simultaneous staining of nucleoproteids and some cathionic proteins. 6 3

Treatment of formalin-fixed mammalian tissues with concentrated or 50% phosphoric acid at 5 degrees C for 20 and 50 min. respectively reveals complete extraction of RNA as judged by methyl green followed by staining with pyronin. This procedure also causes depolymerisation of DNA as indicated by the red staining of the nuclei. Sections treated with concentrated phosphoric acid at 5 degrees C for 30 min. causes disruption of the double helical structure of DNA what results in the depression of the pyronin staining. Similarly treated sections show Feulgen positive nuclei. Treatment of sections in 25 % phosphoric acid at 60 degrees C for 15 min. followed by staining with methyl green and pyronin show red nuclei, nucleoli and the cytoplasm. This indicates that extraction of RNA is only possible in cold and not at elevated temperature.
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PMID:A new rapid method for selective extraction of RNA from fixed mammalian tissues. 7 98

An attempt was made to estimate the number of Escherichia coli K-12 cells rendered permeable to antibiotics under Ca2+ treatment. The effect of cold factor and Ca2+ alone as well as the cell age on the induction of permeability and the energy dependence of the latter were also investigated. About 70-75% and more exponentially growing cells as a result of Ca2+ treatment became sensitive to actinomycin, rubomycin and olivomycin. This number was somewhat lower (40-50%) in sationary phase culture. A fraction (20-30%) of stationary phase cells appeared to be sensitive to antibiotics even without Ca2+ pretreatment. Preincubation of the cells in cold in the absence of Ca2+ cations did not induce the cell permeability. The transport of antibiotics inside the cell was not prevented by an uncoupler of oxidative phosphorylation --carbonylcyanid-m-chlorophenylhydrazone (CCCP). It is suggested that the cells which are rendered permeable to tested antibiotics represent the "compentent" cells capable to uptake molecules of exogenous DNA as well.
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PMID:[Quantity of compentent cells in a population of Escherichia coli treated with Ca2+ cations]. 7 2


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