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use of cross-linking in studying the structure of rna tumour viruses.treatment of intact avian myeloblastosis virus (amv) with dimethyl suberimidate dihydrochloride (dms), a cross-linking agent specific for amino groups, was found to result in progressive cross-linking among viral proteins, as revealed by polyacrylamide gel electrophoresis (page) in the presence of sodium dodecyl sulphate (sds). free viral proteins were not cross-linked. the cross-linked protein complex with an apparent molecular weight of 50,000 daltons was studied in detail.19769823
transmission of alfalfa mosaic virus through nicandra physaloides seeds and its localization in embryo cotyledons.alfalfa mosaic virus (amv) was found to be transmitted through seeds of nicandra physaloids l. the average seed transmission rate of the amv isolates t6, lmbg-4 and st amounted to 23, 4 and 0 per cent, repectively. in the cytoplasm of parenchyma cells of embryo cotyledons of seeds from plants infected with the t6 isolate, electron microscopy revealed amv aggregates of type 2a and aggregations of irregularly viral particles with a tendency to subparallel alignment, representing early stages of ty ...197720770
studies on reverse transcriptase of rna tumor viruses iii. properties of purified moloney murine leukemia virus dna polymerase and associated rnase h.dna polymerase was purified from a cloned isolate of moloney murine leukemia virus (m-mulv). purified m-mulv dna polymerase, upon analysis by polyacrylamide gel electrophoresis, showed one major polypeptide of mol wt 80,000. estimation of molecular weight from the sedimentation rate of the purifed enzyme in a glycerol gradient was consistent with a structure containing one polypeptide. m-mulv dna polymerase could transcribe ribopolymers, deoxyribopolymers, and heteropolymers as efficiently as di ...197546925
properties of oncornavirus rna-directed dna polymerase, the rna template, and the intracellular products formed early during infection and cell transformation.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) c ...197550902
sequences related to the rna tumor viruses in the rna and dna of human leukemias and lymphomas.dna-rna hybridization was used to explore whether human neoplasias contain rna molecules having sequence homologies to those of the rna tumor viruses known to cause similar diseases in animals. the pattern of specific rnas found in the human tumors showed a remarkable concordance with the predictions deducible from the animal systems. thus human breast cancer contains rna homologous only to that of the murine mammary tumor virus (mmtv). human leukemias, sarcomas, and lymphomas (including hodgkin ...197551626
mechanism of interaction of avian myeloblastosis virus reverse transcriptase with avian myeloblastosis virus rna.the synthesis of dna on avian myeloblastosis virus (amv) rna as the primer-template using amv reverse transcriptase in vitro has been examined as a function of the concentrations of these components, as well as a function of the ionic strenth of the assay medium. the results are consistent with the hypothesis that two types of sites exist on the amv rna: inactive "dead-end" sites that merely bind the enzyme, and active binding sites that lead to dna synthesis. velocity sedimentation studies of r ...197656463
evidence for circularization of the avian oncornavirus rna genome during proviral dna synthesis from studies of reverse transcription in vitro.the rna-directed dna polymerase (deoxynucleosidetriphosphate:dna deoxynucleotidyltransferase ec 2.7.7.7) of avian oncornavirus requires a tryptophan trna (trnatrp) primer molecule located close to the 5' end of the viral rna genome for the initiation of dna synthesis in vitro. in this communication we demonstrate that the dna product, transcribed from avian myeloblastosis virus (amv) 35s rna containing only trnatrp as primer, is located also at the 5' end of the rna genome. more importantly, we ...197657620
poly 2'-o-ethylcytidylate, an inhibitor and poor template for amv reverse transcriptase.poly(2'-o-ethylcytidylate) is a poor template-primer for purified avian myeloblastosis virus reverse transcriptase; the relative activities of the template-primers poly(c)-oligo(dg), poly(cm)-oligo(dg) and poly(ce)-oligo(dg) are 23:16:1. a mixture of poly(ce) and poly(di) is inactive as template-primer, in agreement with the observed inability of these to form a helical complex. by contrast the inactivity of poly(ce)-poly(i) is shown to be due to the influence of the 2'-o-ethyl residue. poly(ce) ...197660742
bovine leukemia virus: an exogenous rna oncogenic virus?short term cultures of bovine leukemic lymphocytes release virus particles with biochemical properties of rna oncogenic viruses. these particles, tentatively called bovine leukemia virus (blv) have a high molecular weight-reverse transcriptase complex and a density averaging 1.155 g/ml in sucrose solutions. molecular hybridizations between blv-3h cdna and several viral rnas show that blv is not related to mason-pfizer monkey virus (mpmv) simian sarcoma associated virus (ssv-1) feline leukemia vi ...197664382
[presence in immunostimulated cells of an rna molecule utilizable as template for reverse transcriptase of avian myeloblastosis virus (amv)].cytoplasmic rna extracted from antigen stimulated immunocompetant cells is transcribed in vitro into dna by the rna directed dna polymerase from avian myeloblastosis virus, in the absence of any added primer. cytoplasmic rna from other organs of the same animal, from non-stimulated immunocompetent cells, or from cells in tissue culture is not transcribed in the absence of exogenous primer.197765233
the effect of magnesium and manganese ions on the structure and template activity for reverse transcriptase of polyribocytidylate and its 2'-0-methyl derivative.the secondary structure of the hydrogen bonded hybrids polycytidylate-oligodeoxguanylate (poly(rc)-(dg)12-18 and poly (2'-ome) cytidylate-oligodeoxyguanylate (poly (rcm)-(dg)12-18 was studied at several magnesium and manganese ion concentrations. these hybrids are effective template-primer complexes for the synthesis of poly(dg) by avian myeloblastosis virus (amv) dna polymerase under disparate ionic conditions. circular dichroism spectra and thermal melting data were obtained as a function of i ...197773165
virus-coded origin of a 32,000-dalton protein from avian retrovirus cores: structural relatedness of p32 and the beta polypeptide of the avian retrovirus dna polymerase.a 32,000-dalton protein (p32) located in avian retrovirus cores was immunoprecipitated from [35s]methionine-labeled avian myeloblastosis virus (amv) propagated in cultured chicken embryo fibroblast cells by an antiserum preparation (sarc iii) derived from tumor-bearing hamsters injected with cloned and passaged cells from an avian sarcoma virus-induced primary hamster tumor. since sarc iii serum apparently contained antibodies only to virus-coded proteins and not to chicken cellular proteins, th ...197881316
[immunologic aspects of preparation of antiserum to the reverse transcriptase from avian myeloblastosis virus].after immunization of rabbits the antiserum was prepared against purified reverse transcriptase (revertase) from avian myeloblastosis virus (amv). the antiserum demonstrated enzymeneutralizing antibody activity that was associated with ummunoglobulin g fraction but not with igm. the high antigenicity of amv revertase for rabbits was shown. the active antiserum was obtained after 4 immunizations of rabbit with approximately 20 microgram of the enzyme. non-specific revertase inhibitors were found ...197688006
phosphonoformate inhibits reverse transcriptase.the new antiviral substance phosphonoformate (pfa) has been tested in a cell-free system for its effect on reverse transcriptases from an avian retrovirus (avian myeloblastosis virus, amv) and from mammalian retroviruses (rauscher leukaemia virus, rmulv; bovine leukaemia virus; baboon endogenous virus; simian sarcoma virus; visna virus). the observed inhibitory effect of pfa has been compared with that of a structurally related substance, phosphonoacetate (paa). phosphonoformate, at a concentrat ...197994344
hydrodynamic diameters of rna tumor viruses. studies by laser beat frequency light scattering spectroscopy of avian myeloblastosis and rauscher murine leukemia viruses.the diffusion constants of avian myeloblastosis virus (amv) and murine leukemia virus (mulv) (rauscher) suspensions in buffer and in 30% sucrose were determined by laser beat frequency light scattering spectroscopy at a series of temperatures ranging rom 5 to 25 degrees. by the use of the stokes-einstein equation, the following hydrodynamic diameters are calculated at 20 degrees: mulv, 154 plus or minus 3 nm in sucrose and 145 plus or minus 7 nm in buffer; amv, 144 plus or minus 3 nm in sucrose ...1975162827
inhibition of rna-dependent dna polymerase reaction by 6-(p-hydroxyphenylazo)-uracil: a result of drug induced dithiothreitol oxidation.6-(p-hydroxyphenylazo)-uracil (hpura) reduced by dithiothreitol inhibited amv or rlv virion associated exogenous rna-dependent dna polymerase reactions. however, the inhibition was variable from experiment to experiment and was not consistent with the base specificity of hpura seen for inhibition of gram positive dna-dependent dna polymerases. increasing the concentration of dithiothreitol reversed the inhibition. furthermore, at non-toxic concentrations, hpura did not influence the plating effi ...1975166420
amv rna transcription in cell-free systems and properties of in vitro chromatin-directed rna synthesis.in this report we have presented evidence that viral sequences in the genome of amv-infected myeloblasts can be transcribed in vitro. the rna products synthesized in either nuclei isolated from these cells or by eukaryotic rna polymerase b from the isolated chromatin contained approximately 1% virus-specific sequences. this result, which is in agreement with the fraction of viral rna in infected cells (garapin et al. 1971), is higher than expected from a random transcription of the genome, and t ...1975169005
quantitative and qualitative differences in dna complementary to avian myeloblastosis virus between normal and leukemic chicken cells.hybridization of avian myeloblastosis virus (amv) rna with dna immobilized on filters or in liquid with a vast dna excess was used to measure the viral specific dna sequences in chicken cells. newly synthesized viral dna (v-dna) appears within an hour after infection of chicken embryo fibroblasts (cef) with avian oncornaviruses. a fraction of newly synthesized v-dna becomes integrated into the cellular genome and the remainder gradually disappears. a covalent linkage between v-dna and cellular d ...1975169823
electrophoretic mobilities of rna tumor viruses. studies by doppler-shifted light scattering spectroscopy.we have used laser beat frequency light scattering spectroscopy to measure, at several ph values, the electrophoretic mobilities of purified avian myeloblastosis (amv), murine leukemia (mulv), murine mammary tumor (mumtv), and feline leukemia (felv) viruses. the mobilities of these viruses are similar at ph greater than or equal to7 (-2.7 to -3.2 x 10(-4) (cm/sec)/(v/cm). the isoelectric points of mulv and amv are apparently less than ph 3, whereas for felv the data could be interpreted to indic ...1975170961
homology between avian oncornavirus rnas and dna from several avian species.3h-labeled 35s rna from avian myeloblastosis virus (amv), rous associated virus (rav)-0, rav-60, rav-61, rav-2, or b-77(w) was hybridized with an excess of cellular dna from different avian species, i.e., normal or leukemic chickens, normal pheasants, turkeys, japanese quails, or ducks. approximately two to three copies of endogenous viral dna were estimated to be present per diploid of normal chicken cell genome. in leukemic chicken myeloblasts induced by amv, the number of viral sequences appe ...1975172655
trna's associated with the 70s rna of avian myeloblastosis virus.the distribtuion of various amino acid trna's in the 4s rna components of avian myeloblastosis virus (amv) and in 4s rna prepared from chicken cmbryo cells, chicken myeloblasts, and chicken livers was determined. this was done by aminoacylating the 4s rna samples with a mixture of 17 radioactive amino acids and subsequently identifying the trna-accepted amino acids on an amino acid analyzer after deacylation. in embryo cells, myeloblasts, and liver, trna's accepting all 1m amino acids were demon ...1975172660
evidence for tandem integration of avian myeloblastosis virus dna with endogenous provirus in leukemic chicken cells.the integration site of avian myeloblastosis virus (amv) proviral dna in dna from leukemia chicken myeloblasts has been studied by three sequential nucleic acid hybridizations that can localize the proviral dna according to the repetitiveness of the adjacent cellular dna regions. first, large denatured cellular dna fragments (2.1 x 10(6) daltons) were reassociated and fractionated according to sequence reiteration frequenct. next, dna remaining single-stranded in each fraction was immobilized on ...1976179099
ribonucleotide sequence homology among avian oncornaviruses.rna sequence relatedness among avian rna tumor virus genomes was analyzed by inhibition of dna-rna hybrid formation between 3h-labeled 35s viral rna and an excess of leukemic or normal chicken cell dna with increasing concentrations of unlabeled 35s viral rna. the avian viruses tested were rous associated virus (rav)-3, avian myeloblastosis virus (amv), rav-60, rav-61, and b-77 sarcoma virus. hybridization of 3h-labeled 35s amv rna with dna from normal chicken cells was inhibited by unlabeled 35 ...1975173876
acquisition of viral dna sequences in target organs of chickens infected with avian myeloblastosis virus.the distribution of oncornavirus dna sequences in various tissues of normal chickens and of chickens with leukemia or kidney tumors induced by avian myeloblastosis virus (amv) was analyzed by dna-rna hybridization using 35s amv rna as a probe. all the tissues from normal chickens which were tested contained the same average cellular concentration of endogenous oncornavirus dna. in contrast, different tissues from lekemic chickens and from chickens bearing kidney tumors contained different concen ...1975170415
restricted addition of proviral dna in target tissues of chickens infected with avian myeloblastosis virus.proviral dna is synthesized within an hour after infection of chicken cells with an avian oncornavirus and is integrated into nuclear cellular dna within a short time. the viral dna appears to be synthesized as double-stranded molecules of approximately 6 x 10(6) daltons some of which are converted into supercoiled cricles perhaps as a requisite for integration. the endogenous v-dna in normal chicken cells and both the endogenous and amv v-dna in leukemic chicken myeloblasts are covalently linke ...1976188728
the oncornavirus maturation process: quantitative correlation between morphological changes and conversion of genomic virion rna.avian myeloblastosis virus (amv) was harvested at different time intervals from chick leukemic myeloblasts, and the rate of the maturation process of amv was estimated on the basis of morphological changes in the virions and conversion of genomic viral rna. the change from immature virions characterized by the presence of an electronlucent center to the condensed mature form (with dense nucleoid) was accompanied by the conversion of 30-40s rna to 60s rna. both processes were quantitatively defin ...1976188781
polypeptides isolated from ribosome-like structures occluded in avian myeloblastosis virus (amv).the protein composititon of ribosome-like particles isolated from amv was determined by acrylamide gel electrophoresis and by immunological methods. it was established that the protein spectrum of ribosome-like particles differed significantly form the total protein spectrum of amv. the most characteristic protein components of ribosome-like particles had a molecular weight in the range of 70 000--110 000. apart from these proteins, the viral ribosomal particles contained a small amount of prot ...1975169489
studies on characterization of the integration sites of avian rna tumor virus-specific dna.a sequential hybridization procedure is described which allows the integration sites of viral-specific dna to be characterized according to their reassociation kinetics. in addition, this approach enables us to estimate the size of the integrated viral dna. endogenous virus sequences in normal cells appear to be associated with cell sequences reiterated 1200 times, and each integration unit is approximately equal to one 35s rna subunit. in amv-infected cells, the additional amv-specific dna sequ ...1975169002
homogeneity and complexity of avian oncornavirus proviral dna determined by molecular hybridization.the homogeneity of dna complementary to the 35s rna subunit of avian myeloblastosis virus (amv) has been demonstrated by single or multistep hybridization. for multistep hybridizations, 35s amv rna was preselected for its ability to hybridize either to unfractionated leukemic dna or to leukemic dna enriched for unique or for reiterated sequences. these experiments indicate that the viral genome is complementary to dna sequences with a low reiteration frequency. competition experiments confirm th ...1977191654
preparation of antisera to group-specific antigens of avian leukosis-sarcoma viruses: an alternate approach.immunization of rabbits with a pooled preparation of chromato-graphically purified avian myeloblastosis virus (amv) group-specific (gs) antigens produced relatively large volumes of antiserum that was as broadly reactive in complement-fixation (cf) tests as antiserum produced in hamsters with tumors induced by rous sarcoma virus. this alternate procedure should be of value for routine preparation of leukosis virus gs antiserum. other antisera prepared against disrupted amv had spurious reactivit ...1977194573
purification of viral proteins from avian sarcoma virus qv2.a procedure was established whereby most of the major viral proteins were isolated to apparent homogeneity in biologically and immunologically active forms from a single batch of avian sarcoma virus qv2. for the initial step of purification, gently disrupted virions were fractionated by cscl centrifugation into envelope proteins, rna-dependent dna polymerase, and viral core proteins. further purification of envelope glycoproteins and dna polymerase was performed by affinity chromatography on aga ...1979115857
formation of ribosome-rna initiation complexes with alfalfa mosaic virus rna 4 and rna 3.rna 4 of alfalfa mosaic virus (amv) is a monocistronic messenger for the coat protein. we have determined the sequence of the 40 +/- 2 nucleotides in rna 4 that were protected in the initiation complex formed with wheat germ 80 s ribosomes from digestion by t1 or pancreatic ribonucleases. the aug coat protein initiation codon was near the middle of this protected region. we have found two ribosome-binding sites in rna 3. the principal one, near the 5' end, is the initiation site for the major tr ...1979114984
single-stranded dna from oncornavirus-infected cells enriched in virus-specific dna sequences.we previously found that a minor fraction of single-stranded dna (ss-dna) isolated from native nuclear dna of normal chicken embryonic cells and cells of other species hybridized with bulk nuclear dna or cellular rna in great excess. at least one-third of ss-dna belonging to the nonrepetitious part of the cell genome could be hybridized to homologous rnas. in the present work, similar results were obtained with ss-dna from cells of chickens infected by avian myeloblastosis virus (amv). to invest ...1977198800
cyclophosphamide induced sensitivity against avian rna myeloblastosis virus in age-resistant hosts.the effect of cyclophosphamide administration on survival of 4- to 7-week-old chickens as well as on induction of leukemia after avian myeloblastosis virus (amv) injection was studied. the drug treatment alone did not cause any neoplastic effect in the birds during 4 months of observation. immediate application of amv to cyclophosphamide-pretreated age-resistant chickens induced acute myeloblastic leukemia in about 80 per cent of test animals. the sensitivity of chickens against amv, induced by ...1977201874
size and secondary structure of avian myeloblastosis virus associated ribosomal rna: comparison with cellular and precursor ribosomal rna.ribosomal rna isolated from ribosomes present inside avian myeloblastosis virus (amv) was characterized by electron microscopy using the formamide-urea spreading technique. the molecular weight and the secondary structures were compared with those of r-rna and precursor r-na isolated from host cells, the leukemic myeloblasts. the molecular weight of viral r-rna (1.62 +/- 0.18 x 10(6) and 0.69 +/- 0.10 x 10(6)) and the molecular weight of cellular r-rna (1.63 +/- 0.18 x 10(6) and 0.67 +/- 0.09 x ...1978205195
problems with particle-associated dna polymerase assays in the diagnosis of plasma-suspended viruses.the in vitro reaction results of virus-associated dna polymerases for the demonstration of plasma-suspended particles of avian leukemia virus (amv) and of hepatitis type b virus (hbv) were compared. amv particles could be identified by the transcription of the templates poly mc(dg)12-18, poly rat10, and poly d(at) using standardized reaction mixtures. with comparable test conditions, no dna polymerase activity was found in human plasma containing hbv. these findings and the results of a systemat ...197992114
translation of alfalfa-mosaic-virus rna 1 in the mrna-dependent translation system from rabbit reticulocyte lysates.translation of alfalfa mosaic virus (amv) rnas in the mrna-dependent rabbit reticulocyte cell-free system was examined using different rna concentrations. the pattern of products synthesized under the direction of amv rna 2, 3 and 4 was not or almost not influenced by their concentration. however, depending on the rna 1 concentration either a very large protein of mr 115,000 or a mixture of two smaller proteins, mr 58,000 and 62,000 respectively, was formed. these three proteins represent overla ...1979217681
a new method for the size estimation of the rna genome segments of influenza virus.previous estimates of the size of the rna genome segments of influenza virus have been unreliable because of a lack of suitable rna species as size markers. we have attempted to overcome this problem by utilising the ability of amv reverse transcriptase to synthesise full length dna copies of rna molecules in the presence of a suitable primer. by comparing such dna copies of the rna segments of the influenza virus genome with sequenced restriction fragments from the e. coli plasmid pbr322, we ha ...197988039
endonuclease activity of purified rna-directed dna polymerase from avian myeloblastosis virus.highly purified preparations of rna-directed dna polymerase from avian myeloblastosis virus (amv) contain a mn2+-activated endonuclease activity capable of nicking supercoiled dna. this endonuclease activity co-sediments in glycerol gradients with the alphabeta form of amv dna polymerase, and co-chromatographs with dna polymerase activity on deae-cellulose, phosphocellulose, and heparin-sepharose. it is also present in amv alphabeta-dna polymerase purified by electrophoresis through nondenaturin ...197983998
biochemical and immunological characterization of a reverse transcriptase from human melanoma tissue.an rna-direct dna polymerase was purified from human melanoma tissue by successive column chromatography on deae-cellulose (de-23 and de-52) and phosphocellulose. the purified reverse transcriptase has a mol. wt. of 68,000, a ph optimum of 8.0, a mn2+ optimum of 0.6 mm, and a kcl optimum of 60 mm. the purified enzyme transcribes (ra)n - (dt)12, (rc)n - (dg)18, (ome-rc)n - (dg)18 and a 70s rna from rauscher leukemia virus (rlv), but failed to transcribe (da)n - (dt)12. this enzyme has no terminal ...197883188
effects of benzo(a)pyrene adducts of dna synthesis in vitro.two diol epoxides of benzo(a)pyrene (bp), and benzo(a)pyrene 4,5-oxide, have been used to make adducts in the homopolymers polyribocytidylic acid, (rc); polyriboadenylic acid (ra), polydeoxycytidylic acid (dc) and polydeoxyadenylic acid (da). with appropriate oligomers as primers these modified and unmodified polynucleotides were used as templates for dna synthesis with avian myeloblastosis virus dna polymerase (amv) or e. coli pol i dna polymerase. we have found that: (1) the size of the dna pr ...197882490
reverse transcriptase of foamy virus. purification of the enzymes and immunological identification.reverse transcriptase from foamy virus, strain h4188 was estimated and purified. the enzyme has the following characteristics: 1. the reaction utilized preferentially oligo (dt) poly (ra) as a primer-template; however, the synthetic primer-template oligo (dt) poly (da) could also be used to some extent. 2. the reaction utilized oligo (dg) poly (rc) as a primer-template with very low efficiency. 3. the crude virus preparation had a detectable endogenous reaction using the four deoxyribonucleotide ...197774244
the primary structure of the coat protein of alfalfa mosaic virus strain vru. a hypothesis on the occurrence of two conformations in the assembly of the protein shell.the complete primary structure of the coat protein of strain vru of alfalfa mosaic virus (amv) is reported. the strain is morphologically different from all other amv strains as it contains large amounts of unusually long virus particles. this is caused by structural differences in the coat protein chain. the amino acid sequence has mainly been established by the characterization of peptides obtained after cleavage with cyanogen bromide and digestion with trypsin, chymotrypsin, thermolysin or st ...1979520317
immunological distinction between ribonuclease h activity of alpha and alph beta forms of avian myeloblastosis virus (amv) dna polymerase. 197765831
detection by immunofluorescence of avian myeloblastosis virus reverse transcriptase.peripheral blood cells of avian myeloblastosis virus (amv-(infected chickens were examined at various intervals post infection by immunofluorescence. amv revertase was identified in pro- and myeloblasts; it was localized mainly in the perinuclear zone or throughout the cytoplasm. no revertase was found in erythrocytes or granulocytes. blood cells from uninfected chickens of man contained no revertase.197661720
influence of phosphate on activity and stability of reverse transcriptase from avian myeloblastosis virus.activity of rna-dependent dna polymerase (rddp) from avian myeloblastosis virus (amv), either in purified form or in virus lysates, was increased by phosphorylation. stability of rddp in lysates buffered with phosphate was much greater (no loss of activity in 48 hours at 4 degrees) than that in lysates buffered with tris-cl (76% loss). activity lost in the tris-buffered extracts was completely restored by phosphorylation. the findings suggested that amv rddp activity is influenced by the degree ...197661581
rna-dependent dna polymerase activity of rna tumor virus. vi. processive mode of action of avian myeloblastosis virus polymerase.purified avian myeloblastosis virus (amv) polymerase consisting of alpha,beta subunits has been shown to act processively in catalyzing dna synthesis primed with 34s amv rna oligo(dt), poly(a)-poly(dt), and poly(i)-poly(dc). dna transcripts prepared with 34s amv rna-oligo(dt)14 and amv polymerase (alphabeta) have been shown to have a molecular weight of 1.05 x 10(6), or approximately one-third the size of the 34s rna genome. polymerase subunit alpha acts nonprocessively with the above templates.197661286
on the association of reverse transcriptase with polynucleotide templates during catalysis.the association of avian myeloblastosis virus (amv) dna polymerase with polynucleotide templates during catalysis has been studied. during the course of polymerization, different template-primer complexes were added and the ability of the enzyme to switch from one polynucleotide template to another was determined. at 37 degrees c as well as at 4 degrees c, the polymerase is able to switch from certain template-primer complexes to others. for example, the addition of poly(a)-oligo(dt) during the ...197660129
comparative ability of rna and dna to prime dna synthesis in vitro: role of sequence, sugar, and structure of template-primer.the priming efficiency of oligo(rna) vs. oligo(dna) in a homopolymer template-homooligomer primer system was compared using four dna polymerases. the templates included (dt)n, (da)n, (dc)n, and (di)n. primers were the oligomers of the complementary dna or rna with chain lengths of 6 to 23. the dna polymerases used were from micrococcus luteus, avian myeloblastosis virus (amv), and escherichia coli (polymerase i and polymerase iii). the polymerases demonstrated a preference for the dna primers wi ...19751092334
stepwise dissociation of high molecular weight avian myeloblastosis virus rna: 30-40s rna subunits--the best natural template-primer for viral reverse transcriptase.controlled disruption of 60s amv rna with formamide was used to prepare 50-55s and 30-40s rnas. when the activities of these rnas as templates for amv reverse transcriptase were compared it was found that 50-55s rna was 1-5 times and 30-40s rna 2 to 3 times more active than 60s rna. the 30-40s rna produced by heating, instead of formamide disruption, was inactive as a template but activity was restored by addition of oligo(dt). 40% of the 4s rna initially associated with the 60s rna remained ass ...197659791
analysis of the pancreatic-ribonuclease-digestion products of alfalfa-mosaic-virus ribonucleic acid. sequence homologies between the different rnas.alfalfa mosaic virus (amv) genome consists of three pieces of rna (24-s, 20-s and 17-s rna). for infectivity these three rnas and the coat protein are required. in the absence of coat protein, infectivity is obtained by adding the 12-s rna also normally present in the virus. this 12-s rna represents the message for coat protein. thus a redundancy of the gene for coat protein exists between 12-s rna and one of the other rnas. sequence analysis of the oligonucleotides resulting from pancreatic rib ...19751175651
temperature-dependent template switching during in vitro cdna synthesis by the amv-reverse transcriptase.reverse transcriptase template switching has been invoked to explain several aspects of retroviral replication and recombination, and has been reported in vitro for the moloney murine leukemia virus (m-mulv) reverse transcriptase. during in vitro cdna synthesis, the avian myeloblastosis virus (amv) reverse transcriptase can switch from one template to another in a homology-dependent and temperature-dependent manner. chimeric cdna molecules are generated within 30 min at high incubation temperatu ...19921279521
mechanism of release of active alpha subunit from dimeric alpha beta avian myeloblastosis virus dna polymerase.storage of the dimeric (alphabeta) form of avian myeloblastosis virus (amv) dna polymerase in glycerol resulted in the release of the smaller alpha subunit, as detected by glycerol gradient sedimentation. analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of enzyme stored in glycerol showed the concomitant appearance of several polypeptides and a lowering in the level of both beta and alpha components. this reduction appears to be the result of cleavages introduced by traces o ...197658080
a study of the states of aggregation of alfalfa mosaic virus protein.the states of aggregation of alfalfa mosaic virus (amv) protein have been characterized by sedimentation velocity experiments and electron microscopy. the main association product is a spherical particle with an s value of about 30s. it is highly likely that the assembly of this particle starts with dimers of the 25000 molecular mass unit resulting in an icosahedral particle made of 30 dimers. no intermediate aggregation products have been detected. the clustering pattern of the protein in the c ...197613424
v-src enhances phosphorylation at ser-282 of the rous sarcoma virus integrase.the rous sarcoma virus (rsv) integrase (in) and the beta polypeptide (beta) of the reverse transcriptase are posttranslationally modified by phosphorylation on ser at amino acid position 282 of in. when in was immunoprecipitated from rsv (prague a strain) virions, approximately 30 to 40% of the in molecules were phosphorylated. when in was immunoprecipitated from a v-src deletion mutant (delta mst-a) of rsv or from avian myeloblastosis virus (amv), the percentage of in molecules that were phosph ...19921312616
expression of viral proteins in mammalian cells transformed by avian sarcoma viruses.the expression of viral proteins in nine lines of hamster and rat cells transformed by avian sarcoma viruses (asv) was studied by indirect immunofluorescence with monospecific antisera to purified gp85 and p27 of amv-b and a polyvalent antiserum to all the p proteins of this same virus. the lines of asv-transformed cells were either low virus producers (vp) or inducible or non-inducible non producers (np). cytoplasmic expression of p proteins was observed in all the cell lines except the least i ...1976186419
stepwise transition of aggregate structure of high-molecular-weight avian myeloblastosis virus rna. mode of releasing of associated 4s rna.mode of releasing of associated 4s rna species was studied during a controlled transition of aggregate structure of high-molecular-weight amv-rna. it has been found that associated 4s rna constitutes 2.5% of 60s amv-rna complex. approximately 60% of associated 4s rna is successively released during treatment of viral rna with increasing formamide concentration, concomitantly with the transition of 60s rna aggregate through 50--55s rna intermediate into the final 30--40s rna subunits. 40% of 4s r ...1976180440
separation of time-defined avian myeloblastosis virus (amv) using column cultivation of leukaemic myeblasts.a new technique is described of column cultivation of cells immobilized on sial glass cullet. the technique ensures a controlled and continuous production of time-defined young virus. during the column cultivation the morphological characteristics of tho immobilized cells remain essentially unchanged.1976179904
reverse transcriptase inhibits taq polymerase activity.detection of viral rna by polymerase chain reaction (pcr) requires the prior reverse transcription of the viral rna. in order to minimise the number of manual manipulations required for processing large numbers of samples, we attempted to design a system whereby all the reagents required for both reverse transcription and amplification can be added to one tube and a single, non-interrupted thermal cycling program performed. whilst attempting to set up such a one-tube system with taq polymerase ( ...19921374554
identification of dna in the core component of avian myeloblastosis virus.avian myeloblastosis virus (amv) was found to contain dna associated with the virion. the viral envelope was removed by treating the virus with a nonionic detergent and the dna was found in the core fraction. these experiments indicate that the dna associated with tumor virus is not contaminant associated with the viral envelope and suggest that the dna is part of the internal core component. the dna from avian myeloblastosis virus has a density of 1.70 g/cm3.1976178377
exogenous primer-independent cdna synthesis with commercial reverse transcriptase preparations on plant virus rna templates.upon reverse transcription and cloning manipulations with virion rnas of several plant viruses, namely beet yellows virus, brome mosaic virus, and potato virus x, we came across a significant background synthesis of cdna on the virion rna template in vitro independent of exogenous primers added. when tested with beet yellow virus rna template, several commercial preparations of avian myeloblastosis virus (amv) reverse transcriptase showed the background activity monitored by the [alpha-32p]dntp ...19921381874
renal neoplastic response to leukosis virus strains bai a (avian myeloblastosis virus) and mc29.previous reports described the induction of avian renal neoplasms by leukosis virus strains bai a [avian myeloblastosis virus (amv)] and mc29, and illustrated morphological characteristics of the tumors. continued studies in this work confirm evidence of the origin of the tumors from embryonal cells residual in the posthatched chick. the work further emphasizes differences in histopathology of the neoplasms caused by the two viruses and reveals differences in the histopathogenesis of the respect ...1976177194
nonspecific immunosuppression and expression of avian myeloblastosis virus (bai strain a).chickens were treated with cyclophosphamide in order to induce nonspecific immunosuppression. treated and untreated animals were injected with avian myeloblastosis virus (amv) or myeloblasts at the age when a pronounced resistance to the disease is observed. chickens treated with cyclophosphamide and then challenged with amv developed acute myeloblastic leukemia in 70 percent. similarly treated chickens transplanted with fresh amv producing myeloblasts exhibited 30 percent incidence of myeloblas ...1976187971
inactivation of avian myeloblastosis virus dna polymerase by specific binding of pyridoxal 5'-phosphate to deoxynucleoside triphosphate binding site.avian myeloblastosis virus (amv) dna polymerase is inactivated by preincubation with pyridoxal 5'-phosphate. this inactivation is relatively specific since various pyridoxal-5'-p analogs cause no inactivation. this effect is reversible but can be made irreversible by reduction with sodium borohydride; the reduced pyridoxal-5'-p adduct exhibits a new absorbance maximum at 325 nm and a fluorescence emission at 392 nm when excited at 325 nm. the evidence presented suggests the formation of a schiff ...1977190232
characterization of tumour virus proteins. i. radioimmunoassay of the p27 protein of avian viruses.the major structural protein of avian oncornaviruses, a core component of about 27000 daltons, has been measured by radioimmunoassay. the purified protein was labelled with 125iodine by chloramine-t method. the immune serum titer was defined as the highest serum dilution able to precipitate 50% of the labelled antigen present in the system. standard competition curve was constructed in order to determine the equivalents of protein, in a system with limiting antibody concentration. in the experim ...1977190652
search for virus specific dna sequences and viral particles in mitochondria of avian leukemic myeloblasts.the intracellular localization of the avian myeloblastosis virus (amv) genome was studied. nuclear and mitochondrial dnas from myeloblasts were examined by hybridization with 32p labeled amv-rna of high molecular weight for the presence of virus specific dna sequences. nuclear dna (ndna) from myeloblasts specifically hybridized with viral rna, whereas purified closed circular mitochondrial dna (mtdna) did not hybridize with viral rna. it was therefore concluded that viral genome was present in n ...1977197796
avian myeloblastosis virus rna is terminally redundant: implications for the mechanism of retrovirus replication.we have determined the terminal heteropolymeric sequences of amv rna by the following procedures: first, rna sequence determination on the 5' terminal and the poly(a)-linked 3' terminal t1 oligonucleotides, and second, analysis by the maxam and gilbert (1977) method of amv strong stop dna and of dna complementary to the poly(a)-linked t1 oligonucleotide, synthesized with reverse transcriptase and (pdt)13 as primer. the structure deduced for the 5' terminal region is (5')7mgpppgmccauucuaccucucacc ...1977198142
specific effect of zinc ions on dna polymerase activity of avian myeloblastosis virus.the effect of selected cations on dna synthesis by dna-polymerase of avian myeloblastosis virus (amv) was studied. zinc ions at low concentration (0.2mm) in the assay system enhanced the activity about 2 x fold and at higher concentration (2.0 mm) inhibited the activity completely. in contrast, addition of lithium and potassium salts produced inhibitory effects in this ionic concentration range. replacement of k+ ion had an inhibitory effect on the activity.1978214695
response of hemopoietic cells to avian acute leukemia viruses: effects on the differentiation of the target cells.chicken bone marrow cells were infected with three avian acute leukemia viruses (alv)--avian myeloblastosis virus (amv), myelocytomatosis virus strain mc29 and mill hill 2 virus (mh2)--and then cultured in agar in the presence of conditioned medium. under these conditions, it was found that very few cells served as target cells for these three viruses. density gradient separation showed that alv target cells were found primarily in the light density fractions and might be represented by cells co ...1979222465
an enzyme-linked immunosorbent assay for detecting avian leukosis-sarcoma viruses.immunoglobulins from antiserum raised against chromatographically purified avian myeloblastosis virus (amv) group-specific (gs) antigens were used in enzyme-linked immunosorbent assay (elisa). readily discernible color was produced with 2--3 ng of amv protein in microplate wells coated with 4 micrograms of salt-precipitated immunoglobulins. when a biological assay, i.e., phenotypic mixing (pm), was the criterion for the infectious status of specimens, the elisa consistently identified a greater ...1979230808
purification and characterization of the dna polymerase of human breast cancer particles.previous studies have identified human breast tumor particles possessing many of the features characteristic of rna tumor viruses. in addition to the expected size (600 s) and density (1.16 g/ml) these include possession of an outer membrane and an inner one surrounding a "core" containing a dna polymerase and a large-molecular-weight (70s) rna possessing detectable homology to the rnas of the mouse mammary tumor virus (mmtv) and of the mason-pfizer monkey virus (mpmv). we report here the purifi ...1977265540
the nucleotide sequence of a satellite rna associated with arabis mosaic nepovirus.the nucleotide sequence of a satellite rna (satrna) associated with a lilac isolate of arabis mosaic virus (armv) was determined from cdna copies. the sequence was 1104 nucleotides in length excluding the poly(a) tail, contained a long open reading frame which encodes a polypeptide of 360 amino acids, with an mr of 39k. nucleotide sequence comparisons revealed that the armv-associated satrna shared 83% nucleotide identity with a satrna from grapevine fanleaf nepovirus, but no extensive sequence ...19901693660
cell surface labelling of mononuclear cells with antisera associated to turnip yellow mosaic virus of alphalpha mosaic virus particles. a freeze-etch study.turnip yellow mosaic virus (tymv) and alphalpha mosaic virus (amv) were used as immuno-electron microscopical markers to detect cell surface receptors on mononuclear cells in freeze-etch replicas. tymv particles were conjugated with vacuum-distilled glutaraldehyde to rabbit igg anti-mouse immunoglobulins (tymv-ramig conjugate) or to rabbit igg anti-mouse theta antigen (tymv-ramth conjugate). b-lymphocytes incubated with tymv-ramig conjugate showed either randomly distributed particles or patches ...1977301135
[comparative inhibitory analysis of dna biosynthesis catalyzed by retrovirus reverse transcriptase].comparative study of dna biosynthesis inhibition, catalyzed by avian myeloblastose virus (amv) reverse transcriptase (rt), human immunodeficiency virus (hiv) recombinant and native rt, has been performed. 3'-azido-2',3'-dideoxythymidine 5'-triphosphate (azttp); 3'-azido-2',3'-dideoxythymidine 5'-methylenephosphonate-diphosphate: 3'-azido-2',3'-dideoxythymidine 5'-phosphate-phosponoacetate; 3'-azido-2',3'-dideoxythymidine 5'-phosphate-dibromomethylenephosphonate; 2',3'-o-isopropylidenecytidine 5' ...19901695849
translation by escherichia coli ribosomes of alfalfa mosaic virus rna 4 can be initiated at two sites on the monocistronic message.substantial evidence is provided to corroborate our previous finding that escherichia coli ribosomes recognize two binding sites on the 5' end of alfalfa mosaic virus (amv) rna 4 [for a preliminary report see castel, a., kraal, b., kerklaan, p. r. m., klok, j., and bosch, l. (1977) proc. natl acad. sci. u.s.a. 74, 5509--5513]. translation can start at either site using acphe-trna or fmet-rna as initiator and takes place in the same reading frame along the monocistronic mrna. the size and composi ...1979389629
virus diseases of berry crops in the soviet far east i. identification of some mechanically transmitted viruses, detected in primorye territory.in primorye territory, ussr, cucumber mosaic virus (cmv-i), arabis mosaic virus (amv), raspberry, ringspot virus (rrsv), and tomato ringspot virus (trsv) were identified on berry crops (currant, raspberry, honeysuckel). with respect to indicator plants and physico-chemical and serological properties, the isolates obtained do not differ from other isolates of these viruses, reported on berry crops in europe and north america.1977610231
acyclic nucleotide analogues: synthesis, antiviral activity and inhibitory effects on some cellular and virus-encoded enzymes in vitro.several n-(s)-(3-hydroxy-2-phosphonylmethoxypropyl) (hpmp) and n-(2-phosphonylmethoxyethyl) (pme) derivatives of purine bases (adenine, guanine, 2-aminoadenine, 3-deazaadenine) and cytosine inhibit the growth of various dna viruses. pme-derivatives (pmea, pmeg and pmedap) are also active against retroviruses. both types of nucleotide analogues undergo phosphorylation by cellular nucleotide kinases to their mono- and diphosphates. the phosphorylation with crude extracts of l-1210 cells is potenti ...19901699493
alfalfa mosaic virus rna. determination of the sequence homology between the four rna species and a comparison with the four rna species of cucumber mosaic virus.the method of taylor et al. [taylor, j. m., illmensee, r & summers, j. (1976) biochim. biophys. acta, 442, 324--330 and gould and symons (1977) nucleic acids res. 4, 3787--3802] has been used to transcribe complementary dna probes from the four major rnas of alfalfa mosaic virus (amv). analysis of the kinetics of hybridization of these probes in homologous and heterologous complementary dna . rna hybridization reactions has shown that the sequence of the smallest rna (rna 4), which contains the ...1978720343
synthesis of dna complementary to the mrnas for milk proteins by e. coli dna polymerase i.e.coli dna polymerase i (klenow subfragment) was used for the synthesis of complementary dna with the mrnas for rabbit milk proteins as templates. the cdna formed, contained 200 nucleotides and represented about 20% of the mrna template. the cdna was hybridized specifically to the mrna templates. the klenow subfragment of the e.coli dna polymerase i was as efficient as the avian myeloblastosis virus reverse transcriptase in the synthesis of cdna. the mean size of the cdna fragments obtained with ...1976775441
polymerization and rnase h activities of the reverse transcriptases from avian myeloblastosis, human immunodeficiency, and moloney murine leukemia viruses are functionally uncoupled.the functional interaction between the rna-dependent dna polymerase and the rnase h activities of reverse transcriptases (rts) were examined using a 272 nucleotide long plasmid-derived rna transcript primed in a specific location. properties of the avian myeloblastosis virus (amv) rt, the human immunodeficiency virus rt and the moloney murine leukemia virus rt were examined. all three enzymes formed stable complexes with the primer-template with half-lives ranging from about 16 to 41 s. each enz ...19911708386
3'-c-branched 2'-deoxy-5-methyluridines: synthesis, enzyme inhibition, and antiviral properties.a synthesis scheme for 3'-c-methyl-2'-deoxynucleosides and 3'-c-methylidene-2',3'-dideoxy-5-methyluridine has been proposed with 2-deoxyribose as the starting material. methyl 5-o-benzoyl-2-deoxyribofuranose was oxidized and the mixture of the 3'-keto derivatives was separated into the alpha- and beta-anomers. the beta-keto derivative was converted by reaction with memgbr, and after reaction with thymine and subsequent deprotection 1-(3'-c-methyl-2'-alpha-deoxy-alpha-d-threo-pentofuranosyl)thymi ...19921281882
mechanism of inhibition of the retroviral protease by a rous sarcoma virus peptide substrate representing the cleavage site between the gag p2 and p10 proteins.the activity of the avian myeloblastosis virus (amv) or the human immunodeficiency virus type 1 (hiv-1) protease on peptide substrates which represent cleavage sites found in the gag and gag-pol polyproteins of rous sarcoma virus (rsv) and hiv-1 has been analyzed. each protease efficiently processed cleavage site substrates found in their cognate polyprotein precursors. additionally, in some instances heterologous activity was detected. the catalytic efficiency of the rsv protease on cognate sub ...19921331099
the development of virus-resistant alfalfa, medicago sativa l.we have generated more than 100 transgenic alfalfa plants, via agrobacterium-mediated gene transfer, from genotypes selected from five alfalfa cultivars. these plants express the genes for kanamycin resistance and for the coat protein of alfalfa mosaic virus (amv). the strongest expressers accumulated nearly 500 ng coat protein per mg soluble leaf protein. amv inoculation of protoplasts from these strong expressers indicated that they were resistant to infection by amv, while protoplasts from pl ...19911367011
comparison of hiv-1 and avian myeloblastosis virus reverse transcriptase fidelity on rna and dna templates.a comparison of the fidelity of reverse transcriptases (rt) from human immunodeficiency virus (hiv-1) and avian myeloblastosis virus (amv) is made using rna and dna primer-template molecules in vitro. selected template target sites containing either uracil or thymine are used to measure nucleotide insertion fidelities and to compare the efficiency of extending mismatched nucleotides at primer 3'-termini. hiv-1 reverse transcriptase is observed to incorporate as many as three consecutive mismatch ...19921375233
replication of grapevine fanleaf virus satellite rna transcripts in chenopodium quinoa protoplasts.a set of full-length cdna clones of the satellite rna of grapevine fanleaf nepovirus isolate f13 (gflv-f13) was constructed with a variable number of additional, non-viral nucleotides at the 5' and 3' ends. the biological activity of the rnas transcribed from these constructs was tested in chenopodium quinoa protoplasts using a helper virus. when inoculated with arabis mosaic virus s (armv-s) rna as helper, transcripts with 33 non-viral nucleotides at the 5' end (tr45p4) did not replicate, where ...19921383395
protein truncation is not required for c-myb proto-oncogene activity in neuroretina cells.the v-myb oncogene of avian myeloblastosis virus (amv) differs from its normal cellular counterpart by a truncation at both its amino and carboxyl termini and by a substitution of 11 amino acid residues. we had previously shown that v-myb-containing amv, in the presence of basic fibroblast growth factor, transformed chicken neuroretina (cnr) cells. to understand the mechanism of c-myb activation, we have tested whether avian retroviruses that express the full-length c-myb are also active on cnr ...19921404616
[the technology for isolating the avian myeloblastosis virus in high titers from leukosis-free chicks].in order to enhance the outcome of high-quality reverse transcriptase enzyme, an efficient biotechnology was developed of accumulating and isolating the avian myeloblastosis virus (amv) in high titres from blood plasma of leukosis-free chickens. when commercial chickens are infected in most sensitive one-day age, the virus titre does not exceed the value of 10(12) particles per 1 ml of plasma. we used 3-4-day old leukosis free chickens and achieved a stable average titre of the virus of 5.10(12) ...19921430580
identification of genes differentially expressed in two types of v-myb-transformed avian myelomonocytic cells.in an earlier study we found that different forms of the v-myb oncogene transform myeloid cells which resemble either monoblasts [when v-myb of avian myeloblastosis virus (amv) was used] or promyelocytes [when a point mutant in v-myb of amv was used; introna, m., golay, j., frampton j., nakano, t., ness, s.a. & graf, t. (1990). cell, 63, 1287-1297]. in the present study we have searched for genes expressed in amv mutant-transformed promyelocytes that are not expressed in amv-transformed monoblas ...19921549365
transforming potential of truncated v-myb and stimulation of replication by gag-myb fusion products.we have previously reported that truncated forms of the v-myb oncogene of avian myeloblastosis virus (amv) are expressed in transformed chicken embryo fibroblasts (cef). in this paper, we show that deletion mutants encoding v-myb products altered in either the dna-binding or the negative regulatory domains are able to induce cef transformation. in addition, we report that recombinant plasmids expressing gag-myb fusion proteins are maintained as extrachromosomal forms in transfected cells. this o ...19921549366
amino-acid sequence comparison of nepovirus coat proteins.the amino acid sequence of the coat proteins of several nepoviruses was determined by a combination of peptide and nucleic acid sequencing (grapevine fanleaf virus, arabis mosaic virus, tomato blackring virus, grapevine chrome mosaic virus). these sequences were compared and showed homologies ranging from 10% to 69%, and 96.7% for the two arabis mosaic virus strains. 10% homology does not reflect any relationship between viruses, and our results implicate, that nepoviruses, considering the homol ...19921589965
extension of the dna binding consensus of the chicken c-myb and v-myb proteins.the chicken c-myb gene and the v-myb oncogene transduced by avian myeloblastosis virus (amv) encode dna binding transcription activators. the dna binding domain of amv v-myb displays a number of amino acid changes relative to c-myb; v-myb proteins in which one or more of three crucial residues in the dna binding domain are mutated to resemble the c-myb sequence display altered transformation phenotypes. in order to establish whether the spectrum of dna binding sites which amv v-myb can recognise ...19921620600
cdna cloning of a homeobox-containing gene expressed in avian myeloblastic virus-transformed chicken monoblastic leukaemia cells.by combining the polymerase chain reaction and differential library screening, a cdna for an mrna expressed in chicken avian myeloblastosis virus (amv)-transformed monoblasts was isolated. this mrna is not expressed in erythroblast or t-lymphoblast cell lines. induced differentiation of the cells of the amv-transformed bm2 line was associated with reduced levels of this transcript. the predicted protein product of chox m was a homeodomain factor similar to murine hox-4.3.19911674560
relationship of 2',3'-cyclic nucleotide 3'-phosphohydrolase activity of large enveloped rna viruses to host cell activity.purified virions of the large rna viruses show 2',3'-cyclic nucleotide 3'-phosphohydrolase (3'-cnpase) activity. the 3'-cnpase activity is virion-associated and stimulated by their treatment with nonionic detergents. cytopathic viruses such as influenza a2 (singapore/57), ndv, and vsv showed the specific activity of a virion-associated 3'-cnpase equal to or lower than the specific activity of host cell enzyme. retroviruses are an example of extreme relationship of 3'-cnpase to virion. with the a ...19911688073
[rna-dependent dna-polymerase from avian myeloblastosis virus: effectiveness of interaction with oligothymidylate primers of various length].optimal conditions for the reaction of polymerization catalyzed by rna-dependent dna-polymerase from amv on poly(a)- and poly(da)-templates with d(pt)n-primers were established. optimal concentrations of the components and ph of the reaction mixtures were found out to differ significantly. dttp was shown to be both a nucleotide substrate and a minimal primer of the polymerization. the km values for d(pt)2-primer (km = 0.11 mm and 0.54 for poly(a) and poly(da)-templates, respectively) and longer ...19901694567
characterization of alfalfa-mosaic-virus protein polymerization in the presence of nucleic acid.the polymerization of alfalfa mosaic virus (amv) protein in the presence of homologous nucleic acids and a number of other natural and synthetic nucleic acids was studied. the conditions for optimal assembly were found to be ph 6.0 and low ionic strength (i = 0.1 m) at room temperature, irrespective of the type of nucleic acid. the resulting nucleoprotein particles exhibited the same structural characteristics as the virus. this information emerged from optical diffraction and computer filtering ...1978624280
effects of 5' and 3' truncations of the myb gene on the transforming ability of avian myeloblastosis virus (amv).proviruses based on the avian myeloblastosis virus (amv) have been constructed which code for variations of the c-myb and/or v-myb gene product. these proviruses have been used in a soft colony agar assay to assess the contributions of the 5' and 3' deletions of the v-myb oncogene in the cellular transforming activity of the virus. the results indicate that 3' truncations are an integral part of the gene's mechanism of activation and that the truncations on the 5' end of the gene are important e ...19902158185
monocistronic translation of alfalfa mosaic virus rnas.the four alfalfa mosaic virus rnas (respectively 24 s, 20 s, 17 s and 12 s) have been used separately as messengers in two in vitro protein synthesizing systems: wheat germ and rabbit reticulocyte lysate. in both systems a polypeptide corresponding to the translation of the entire length of the rna can be found for rnas 24 s, 20 s and 12 s, but not for 17 s rna, the translation product of which is only 35,000 daltons. the number of initiation sites has been determined for each rna by analyzing t ...1977866193
structural studies on the coat protein of alfalfa mosaic virus. isolation and characterization of the tryptic peptides and the alignment of the cyanogen-bromide fragments.the reduced and carboxymethylated coat protein of alfalfa mosaic virus (amv 425) was fragmented by means of cyanogen-bromide cleavage. the tryptic peptides from the protein and its four cyanogen-bromide fragments were isolated on a preparative scale by combinations of column and paper separation techniques. the tryptic digest of the carboxymethylated protein contained 24 peptides and two free amino acids. all peptides have been characterized by amino acid analyses and end-group determinations. t ...19751175586
on the early emergence of reverse transcription: theoretical basis and experimental evidence.reverse transcriptase (rt) was first discovered as an essential catalyst in the biological cycle of retroviruses. however, in the past years evidence has accumulated showing that rts are involved in a surprisingly large number of rna-mediated transpositional events that include both viral and nonviral genetic entities. although it is probable that some rt-bearing genetic elements like the different types of aids viruses and the mammalian line family have arisen in recent geological times, the po ...19921282161
transformation of chicken myelomonocytic cells by a retrovirus expressing the v-myb oncogene from the long terminal repeats of avian myeloblastosis virus but not rous sarcoma virus.to test the effect of long terminal repeat (ltr) regulatory sequences on the transforming capability of the v-myb oncogene from avian myeloblastosis virus (amv), we have constructed replication-competent avian retroviral vectors with nearly identical structural genes that express v-myb from either amv or rous sarcoma virus (rsv) ltrs. after transfection into chicken embryo fibroblasts, virus-containing cell supernatants were used to infect chicken myelomonocytic target cells from preparations of ...19921323701
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