Publications

TitleAbstractYear
Filter
PMID(sorted ascending)
Filter
use of a specific probe for ovalbumin messenger rna to quantitate estrogen-induced gene transcripts.dna complementary to purified ovalbumin messenger rna (cdna ov) was synthesized in vitro using rna-directed dna olymerase from avian myeloblastosis virus. this cdnaov was then employed in hybridization assays to determine the effect of estrogen on the number of ovalbumin mrna (mrnaov) molecules per tubular gland cell of the chick oviduct. the changes in mrnaov were measured in immature chicks during primary stimulation, after hormone withdrawal and again following secondary stimulation of the ch ...197550081
quantitation of rna tumor viruses by spectroscopy of density gradient gels.we have developed a system for virus particle quantitation based on the measurement of the optical absorbance of stained viruses which first have been banded at their buoyant density in an equilibrum 24 to 53% (wt/wt) sucrose density gradient, then fixed in position in the gradient by photopolymerizing an acrylamide-riboflavin mixture in the sucrose, and finally stained and destained. using plasma from mice infected with leukemia virus (rauscher) or chickens infected with avian myeloblastosis vi ...197551099
specific binding of tryptophan transfer rna to avian myeloblastosis virus rna-dependent dna polymerase (reverse transcriptase).the ability of tryptophan trna (trnatrp) to initiate reverse transcription of the 70s rna of avian rna tumor viruses suggested that the reverse transcriptase (rna-dependent dna polymerase; deoxynucleosidetriphosphate: dna deoxynucleotidyltransferase; ec 2.7.7.7) might have a specific binding site for the trna. a complex of trnatrp and the avian myeloblastosis virus reverse transcriptase has been demonstrated using chromatography on sephadex g-100 columns. of all the chicken trnas, only trnatrp a ...197552156
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
gene specific priming of complementary dna synthesis.dna, complementary to chicken globin mrna was synthesized using either avian myeloblastosis virus reverse transcriptase, or e. coli dna polymerase i. transcriptase cdna sediments at 9 s on sucrose gradients, and is 620 nucleotides in length, representing a complete copy of globin mrna template. in contrast, polymerase i cdna sediments at 4 s, is 100 to 200 nucleotides in length, and is a copy of a small region at the 3'(poly a) end of globin mrna. similarly, transcriptase cdna and polymerase i c ...197664922
[revertase in myeloblasts of chickens infected with avian myeloblastosis virus].revertase present in the myeloblasts of chickens infected with avian myeloblastosis virus failed to synthetise dna in vitro on the endogenous viral template. enzyme inhibitors were not blocking this synthesis. it was rather impaired by incompletness of viral rna in immature virus particles.197772475
purification and further characterization of an rna-dependent dna polymerase from the allantoic fluid of leukosis-virus-free chicken eggs.the purification of an rna-dependent dna polymerase from the allantoic fluid of uninfected, embryonated chicken eggs is described in detail. comparison to the polymerase of avian myeloblastosis virus shows that the two enzymes are different with respect to ion concentrations for optimal reaction, response to increasing concentrations of substrate, thermal stability and protection from thermal inactivation by viral rna. it is concluded that the enzymes compared to each other are different protein ...197772662
binding of trna to reverse transcriptase of rna tumor viruses.the interaction of trna with the reverse transcriptase (rna-dependent dna polymerase) of mammalian rna viruses, such as moloney murine leukemia virus and simian sarcoma virus, has been studied. whereas the purified reverse transcriptase of mammalian viruses sedimented in glycerol gradients as a globular protein with a molecular weight of 70,000, after interaction with trna the enzyme cosedimented with a protein of 150,000 molecular weight. the twofold increase in molecular weight could be a resu ...197877907
normal chicken cells (chf-) express a surface antigen which cross-reacts with determinants of the major envelope glycoprotein (gp85) of avian myeloblastosis virus. 197878565
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
isolation and characterization of a virus-specific ribonucleoprotein complex from reticuloendotheliosis virus-transformed chicken bone marrow cells.chicken bone marrow cells transformed by reticuloendotheliosis virus (rev) produce in the cytoplasm a ribonucleoprotein (rnp) complex which has a sedimentation value of approximately 80 to 100s and a density of 1.23 g/cm3. this rnp complex is not derived from the mature virion. an endogenous rna-directed dna polymerase activity is associated with the rnp complex. the enzyme activity was completely neutralized by anti-rev dna polymerase antibody but not by anti-avian myeloblastosis virus dna poly ...197881319
reverse transcriptase from avian myeloblastosis virus.from lots of 20 to 30 g of avian myeloblastosis virus rna-dependent dna polymerase was obtained in preparations of purity greater than 95% by using a two-step column chromatographic procedure employing deae (de 52) and carboxymethylcellulose (cm 52.). yields of rna-dependent dna polymerase varied from approximately 20,000 to 35,000 u/g of virus. specific activity of the enzyme was about 35,000 to 60,000 u/mg of protein. free of detectable rnase activity, the product exhibited a molecular weight ...197985721
immunochemical studies of beef pancreas tryptophanyl-trna synthetase and its fragments. determination of the number of antigenic determinants and a comparison with tryptophanyl- trna synthetases from other sources and with reverse transcriptase from avian myeloblastosis virus.the immunoglobulin g (igg) fraction of the antiserum from rabbits immunized with homogeneous beef pancreas tryptophanyl-trna synthetase inhibits the enzyme activity in the reactions of both trnatrp aminoacylation and tryptophan activation. fab fragments of igg act in a similar way. common antigenic determinants have been detected in tryptophanyl-trna synthetases from beef, pig, chicken and rat livers using pure antibodies against beef pancreas tryptophanyl-trna synthetase. this observation indic ...197989031
[separation of cellular and viral dna polymerase from oncornavirus infected chicken cells].rna-directed dna polymerase was isolated from the liver, spleen, and myeloblasts of chickens that had been infected with virus of avian myeloblastosis. the enzyme was chromatographically purified from the myeloblasts and brought to about 1,000-fold concentration. the method consisted in cell fractionation, lysis of the microsomal fraction, chromatography on sephadex g-200 and phosphocellulose, as well as ultracentrifugation in the glycerol gradient. the cellular dna polymerases alpha and beta we ...197993956
immunodiffusion study on group-specific antigen of mc-29 chicken hepatoma.rabbit serum against crude mc-29 hepatoma extract does not contain anti-avian gs antibodies detectable by gel diffusion methods. rabbit serum containing antibodies against purified gs 1, gs 2, gs 3 and gs 4 antigens of avian myeloblastosis virus reveals gs 1 antigen in mc-29 hepatoma extract.197995333
interspersion of sequences in avian myeloblastosis virus rna that rapidly hybridize with leukemic chicken cell dna.liquid hybridization of progressively smaller fragments (35s, 27s, 15.5s, 12.5s, and 8s) of poly(a)-selected avian myeloblastosis virus rna with excess dna from leukemic chicken myeloblasts revealed that all sizes of rna contained sequences complementary to both slowly and rapidly hybridizing cellular dna sequences. apparently, the rna sequences which hybridize rapidly with excesses of cellular dna are not restricted to any one region of the avian myeloblastosis virus 35s rna. instead, they appe ...1975163372
isolation of two subgroup-specific leukemogenic viruses from standard avian myeloblastosis virus.two populations of virus having subgroup-specific homogeneity (a and b) were isolated from standard avian myeloblastosis virus stocks by passage in vivo through genetically defined chickens. each possesses leukemogenic activity in vivo. other properties and potential usefulness of these agents are discussed.1975163925
two levels of genetic resistance to lymphoid leukosis.two levels of genetic resistance to lymphoid leukosis are recognized: 1) cellular resistance to virus infection; and 2) resistance to tumor development in leukosis-virus-infected birds. resistance to infection is simply inherited but is very specific for the subgroup of virus. inheritance of resistance to tumor development is more complex but appears to be less subgroup-specific. a breeder may wish to select for resistance to infection of virus eradication is the goal. if his goal is the reducti ...1975168849
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
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
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
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
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
comparison of an avian osteopetrosis virus with an avian lymphomatosis virus by rna-dna hybridization.myeloblastosis-associated virus (mav)-2(0), a virus which was derived from avian myeloblastosis virus and induced a high incidence of osteopetrosis, was compared with avian lymphomatosis virus 5938, a recent field isolate which induced a high incidence of lymphomatosis. the following information was obtained. (i) mav-2(0) induced osteopetrosis, nephroblastoma, and a very low incidence of hepatocellular carcinoma. no difference was seen in the oncogenic spectrum of end point and plaque-purified m ...1975173880
rate of virus-specific rna synthesis in synchronized chicken embryo fibroblasts infected with avian leukosis virus.the rate of avian leukosis virus (alv)-specific rna synthesis has been examined in bot- uninfected and alv-infected synchronized chicken embryo fibroblasts. rna from cells labeled for 2h with [3h]uridine was hybridized with avian myeloblastosis virus poly(dc)-dna, and the hybridized rna was analyzed with poly(i)-spephadex chromatography. approximately 0.5% of the rna synthesized in alv-infected cells was detected as virus specific, and no more than a twofold variation in the rate of synthesis wa ...1976176421
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
avian myeloblastosis virus-induced lymphosarcoma producing erythroblastic leucosis in chicks.acute myeloblastosis and several forms of tumor, including one case of lymphosarcoma occurred when avian myeloblastosis virus (bai-a strain) was inoculated into newly hatched chicks (spf). the homogenate of lymphosarcoma inoculated intraperitoneally into other newly hatched chicks induced a high incidence of erythroblastic leucosis. electron microscopy did not reveal the presence of c-type virus particles in the tumor tissue. the relationship between avian myeloblastosis virus, lymphosarcoma and ...1975179285
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
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
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
biological characterization of avian osteopetrosis.chicks infected as 12-day-old embryos with an end-point purified derivative of avian myeloblastosis virus developed a rapidly progressive osteopetrosis that manifested within 1 week of hatching. a detailed comparison of osteopetrotic chicks and normal hatchmates revealed the following. (i) osteopetrotic chicks exhibited a stunting syndrome, growing at a mean rate that was 26% of the control rats. (ii) at autopsy, the mass of the lymphoid organs was reduced, whereas the mass of the heart, pancrea ...1977197009
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
[cellular contaminants and structural proteins of rous sarcoma virus (rsv), studied by polyacrylamide gel electrophoresis].the number of polypeptides in highly purified preparations of rsv, of two different subgroups, produced in culture, has been compared to the polypeptides present in the supernatant of uninfected cultures and processed in identical manner. the analysis of page-sds shows that from 13 to 18 polypeptides present in viral preparations may be cellular contaminants. fewer contaminating polypeptides are found in the myeloblastosis virus purified from plasma of chicken.1977199367
measurement of proviral genes in uninfected and avian myeloblastosis virus-infected cells by hybridization with 3h-labeled complementary dna probe excess.viral rna (vrna) from avian myeloblastosis virus or dna from virus-infected and uninfected cells was hybridized with [3h]dna complementary to viral rna ([3h]cdna) under conditions of [3h]cdna excess. when [3h]cdna was used to drive the hybridization reaction with vrna, a rate constant of 33.2 liters/mol-s was obtained. the same rate constant was obtained when vrna excess was used as the driver. the specific activities of the [3h]dna probe, estimated from kinetic measurements of the hybridization ...1977199736
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
isolation of the proviral coding strand of avian myeloblastosis virus from leukemic chicken myeloblast by affinity chromatography. 1978210689
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
stimulation of sugar uptake and glycolysis in chicken embryo fibroblasts by the major glycoprotein from avian myeloblastosis virus.addition of purified major glycoprotein from avian myeloblastosis virus to growing or quiescent chicken embryo fibroblasts rapidly stimulates the rate of hexose transport and increases the lactic acid production. these stimulatory effects are dependent on the time of exposure and the dose of viral glycoprotein. in contrast, the glycoprotein only marginally affects hexose transport in chicken cells transformed by rous sarcoma virus. some effects of the glycoprotein on serum-starved quiescent cell ...1979223157
thymic dependence of cell-mediated immunity to avian sarcomas in chickens. immunological characterization of a nonvirion antigen in virus-infected cells. 1979223766
characterization of an adenosine triphosphatase from myeloblasts infected with the avian myeloblastosis virus.an adenosine triphosphatase (atpase ec 3.6.1.3) was partially purified from myeloblasts of chicken infected with the avian myeloblastosis virus and some of its molecular, catalytic and immunological properties were compared with that of the atpase purified from the virus. both the enzymes possessed almost same electrophoretic mobility, molecular weight, s20,w value, substrate specificity, metal-ion requirement, apparent km value and sensitivity to inhibitors and activator. evidence also indicate ...1979225174
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
synthesis of full length cdnas from four partially purified oviduct mrnas.total poly(a)-containing rna prepared from hen oviduct and centrifuged on an isokinetic sucrose gradient displays four peaks of optical absorbance. these have been identified by translation in vitro as lysozyme, ovomucoid, ovalbumin, and conalbumin mrnas. isolation and recentrifugation of the peaks results in partial purification of each mrna. molecular weights have been determined for the mrnas on agarose gels containing 20 mm methylmercury hydroxide. each mrna possesses a number of apparently ...1978632280
effect of estrogen on gene expression in the chick oviduct. effect of estrogen on the sequence and population complexity of chick oviduct poly(a)-containing rna.total cellular rna preparations were isolated from chicken oviducts at three different development stages: (a) immature chicks which were chronically stimulated with estrogen; (b) estrogen-stimulated chicks which were then withdrawn from hormone for 12 days; and (c) laying hens. total cellular rna containing 3'-poly(a) sequences (poly(a)-rna) were than isolated from these preparations using oligo(dt)-cellulose chromatography. the number average nucleotide length of the poly(a)-rna preparations i ...1976932004
reiteration frequency of the gene for tissue-specific histone h5 in the chicken genome.chicken erythroid cells contain a tissue specific histone known as h5 in addition to the five major histone species found in other organisms. the mrna coding for this histone has been isolated by indirect immunoprecipitation from immature, non-dividing reticulocytes in which this is the only histone synthesised. the mrna has been modified by the enzymatic addition of a 3' polyadenylic acid tract, and transcribed into complementary dna (cdna) using the rna-dependent dna-polymerase from avian myel ...19761250413
proviral rearrangements and overexpression of a new cellular gene (nov) in myeloblastosis-associated virus type 1-induced nephroblastomas.histological and anatomopathological studies performed on 152 independent myeloblastosis-associated virus type 1 (mav1)-induced nephroblastomas allowed us to precisely define the chronology of tumor development in chickens. three tumors representing increasing developmental stages were used to construct genomic libraries and to study both the state of proviral genomes and the sites of mav1 integration in genomic dna. we established that increasing levels of proviral rearrangement, eventually lea ...19921309586
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
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
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
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
1 alpha,25-dihydroxyvitamin d3 regulates the transcription of carbonic anhydrase ii mrna in avian myelomonocytes.carbonic anhydrase ii (caii) is highly expressed in the osteoclast, where it is involved in the process of extracellular acidification required for bone resorption. we have previously shown that 1 alpha,25-dihydroxyvitamin d3 [1,25(oh)2d3], a steroid hormone that regulates the differentiation of macrophages and osteoclasts, induces the expression of caii mrna and protein in avian bone marrow cells. to determine whether this regulation occurred at the gene level, we have studied the effects of 1, ...19921584805
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
production of v-myb and c-myb in insect cells infected with recombinant baculoviruses.recombinant baculoviruses expressing the v-myb and c-myb genes in infected insect cells were constructed. the electrophoretic mobilities of their immunoreactive products were the same as those of the authentic myb proteins from chicken cells. the system provides a convenient source of relatively large amounts of v-myb or c-myb for in vitro binding studies.19921639269
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
definition of functional domains in p135gag-myb-ets and p48v-myb proteins required to maintain the response of neuroretina cells to basic fibroblast growth factor.the v-myb- and v-ets-containing e26 retrovirus induces the proliferation of chicken neuroretina (cnr) cells in minimal medium. proliferation of e26 cnr cells is strongly stimulated by basic fibroblast growth factor (bfgf). the v-myb-containing avian myeloblastosis virus also induces the proliferation of infected cnr cells stimulated by bfgf. both e26 cnr and avian myeloblastosis virus cnr cells are able to form colonies in soft agar in the presence of bfgf. this suggests that the v-myb product, ...19921727478
proto-oncogene expression in avian hematopoietic tissues.previous findings from this laboratory (kim & baluda, 1988) have shown that the proto-oncogenes ets, fps, mht (raf), myc and rel are expressed in avian myeloblastosis virus (amv)-transformed cells, whereas the myb gene is repressed. in this study five different chicken hematopoietic tissues which contained varying concentrations of target cells for amv transformation were analyzed to determine whether the expression of these proto-oncogenes resulted from, or was altered by, v-myb-induced leukemo ...19911886713
v-myb transformation of xeroderma pigmentosum human fibroblasts: overexpression of the c-ha-ras oncogene in the transformed cells.human xeroderma pigmentosum "normal" fibroblasts as16 (xp4 vi) were transformed after transfection with a recombinant v-myb clone. in this clone (pkxa 3457) derived from avian myeloblastosis virus (amv), the expression of the oncogene sequences is driven by the amv u-5 ltr promoter. the transformed cells (askxa), which have integrated a rearranged v-myb oncogene, grow in agar, are not tumorigenic in nude mice, and express a 45-kda v-myb protein. the hmw dna of these cells transform chicken embry ...19911893942
protein truncation is required for the activation of the c-myb proto-oncogene.the protein product of the v-myb oncogene of avian myeloblastosis virus, v-myb, differs from its normal cellular counterpart, c-myb, by (i) expression under the control of a strong viral long terminal repeat, (ii) truncation of both its amino and carboxyl termini, (iii) replacement of these termini by virally encoded residues, and (iv) substitution of 11 amino acid residues. we had previously shown that neither the virally encoded termini nor the amino acid substitutions are required for transfo ...19912072904
heterogeneities in vertebrate trnas(trp) avian retroviruses package only as a primer the trna(trp) lacking modified m2g in position 7.bovine, rabbit and chicken trna(trp) species and trna(trp) packaged in avian myeloblastosis virus were separated and purified using two-dimensional gel electrophoresis and their primary structures were determined. two major trna(trp) species (1 and 2) were identified in beef and rabbit, two minor ones (3 and 4) in beef and only one minor in rabbit. their structures differ by 4 nucleotide substitutions located in the d, s and t loops (positions 16, 47, 57 and 59). species 3 and 4 differ from one ...19902156227
transformation by v-myb correlates with trans-activation of gene expression.the v-myb oncogene of avian myeloblastosis virus causes acute myelomonocytic leukemia in chickens and transforms avian myeloid cells in vitro. its protein product p48v-myb is a nuclear, sequence-specific, dna-binding protein which activates gene expression in transient dna transfection studies. to investigate the relationship between transformation and trans-activation by v-myb, we constructed 15 in-frame linker insertion mutants. the 12 mutants which transformed myeloid cells also trans-activat ...19902160580
binding properties of avian retroviral proteins. iii. binding of protein aslv ma(p19) to viral rna and proviral dna.the binding of the avian retroviral matrix protein aslv ma(p19) to homologous viral ssrna and proviral dsdna was analysed using electron microscopic methods combined with a special computer evaluation. no binding affinity of ma(p19) to homologous nondenatured or denatured viral rna was found. in contrast, aslv ma(p19) was shown to have one specific binding site on mav-1 proviral dsdna at position 6795 +/- 345 bp from the 5' end of the molecule. a second specific binding site was found in a cellu ...19902160895
developmental regulation of c-myb in normal myeloid progenitor cells.hematopoietic tissues and some leukemic cell lines express elevated levels of c-myb transcripts. we have separated a subpopulation of chicken embryo yolk sac cells that represents about 5% of the yolk sac hematopoietic cells and appears to contain all of the detectable c-myb transcripts. the level of myb expression in this cell population is higher than previously reported for any normal cell population and is in the range of that found in cells transformed by avian myeloblastosis virus and e26 ...19852413449
detection of antibodies to avian reverse transcriptase by indirect elisa.an improved indirect elisa test for detection of antibodies to the reverse transcriptase (revertase) is described. the sensitivity of the revertase elisa test was compared to that of the revertase inhibition test. serum samples of various origin and sera of specific pathogen free (spf) hens were examined for the revertase antibodies. the presence of these antibodies in the sera of spf chickens is discussed.19862425612
transforming potential of the v-myb oncogene from avian myeloblastosis virus: alterations in the oncogene product may reveal a new target specificity.transfection of brown leghorn chicken embryo fibroblasts by dna containing v-myb sequences cloned either in a complete amv proviral dna or in a retroviral derived vector has led to the isolation of two kinds of transformed cells. a characterization of the proviral sequences retained and expressed in these transformed cells revealed that they contained either new or altered v-myb-related rna species. the experiments presented in this paper also show that both types of transformants expressed trun ...19862427128
association of persistent synthesis of viral dna with macrophage accessory cell dysfunction induced by avian retrovirus myeloblastosis-associated virus of subgroup b inducing osteopetrosis in chickens.this investigation concentrates on a regenerative anemia and immunosuppression occurring in the absence of osteopetrosis. polyclonal activation of t-cells was used as an in vitro test system to study immunosuppression induced by the avian myeloblastosis-associated virus of subgroup b inducing osteopetrosis [mav-2(o)]. t-cell unresponsiveness in vitro was attributed to a defect in an accessory cell function of the macrophage. counterflow centrifugation fractionation followed by mixing experiments ...19872444336
mapping of a small phosphopeptide at the carboxyterminus of the viral myb protein by monoclonal antibodies.several myb-specific monoclonal antibodies were produced and their antigen recognition sites characterized using a series of bacterially expressed truncated myb proteins. the monoclonal antibodies were used for analysing the in vivo phosphorylation site of the oncogene protein from avian myeloblastosis virus (amv), p48v-myb. the p48v-myb protein labeled metabolically with [32p]orthophosphate was isolated from the amv-transformed chicken myeloblast cell line bm-2 by immunoaffinity chromatography. ...19892464784
the ets sequence is required for induction of erythroblastosis in chickens by avian retrovirus e26.e26 is a replication-defective avian retrovirus that causes an erythroblastic leukemia in vivo and transforms hematopoietic precursor cells of both the erythroid and the myeloid lineages in vitro. the e26 genome contains two sets of cell-derived sequences, ets and myb. myb sequences are also present in avian myeloblastosis virus, which transforms myeloblasts exclusively. to determine whether the ets sequence is responsible for the erythroid specificity of e26, we analyzed the transforming activi ...19892535740
the v-myb oncogene product binds to and activates the promyelocyte-specific mim-1 gene.the v-myb oncogene induces myeloid leukemias in chickens, transforms myeloid cells in vitro, and encodes a sequence-specific dna binding protein. we used differential hybridization to screen for v-myb-regulated genes in cells transformed by a temperature-sensitive mutant of the oncogene and identified a new gene, mim-1, which encodes a specifically expressed, secretable protein contained in the granules of both normal and v-myb-transformed promyelocytes. the promoter of the mim-1 gene contains t ...19892688896
avian retroviral long terminal repeats bind ccaat/enhancer-binding protein.dna-protein interactions involving enhancer and promoter sequences within the u3 regions of several avian retroviral long terminal repeats (ltrs) were studied by dnase i footprinting. the rat ccaat/enhancer-binding protein, c/ebp, bound to all four viral ltrs examined. the rous sarcoma virus binding site corresponded closely to the 5' limit of the ltr enhancer; nucleotides -225 to -188 were protected as a pair of adjacent binding domains. the fujinami sarcoma virus ltr bound c/ebp at a single si ...19892725492
[the effect of 3'-azido-2',3'-dideoxythymidine on experimental viral infections].3'-azido-2',3'-dideoxythymidine (az-t) inhibited effectively the reproduction of some retroviruses; among these viruses were the four serological subgroups of sarcoma raus virus in chicken embryo, avian myeloblastosis virus and erythroblastosis virus in chicken. this inhibition was specific towards retroviruses and practically was not observed in the case of infections dna- and rna-genome model viruses of vaccinia and influenza, at whose reproduction reverse transcriptase is not involved. three ...19872821379
[induction of tumors of the meningeal membranes in chicks by the avian myeloblastosis virus].the meningiomas could be easily produced by intracerebral injection of the avian myeloblastosis virus (0.01 ml of virus suspension with titer 10(9)-10(12) pfu/ml) into highly susceptible (white leghorn anya cross) or randomly bred newborn (24-48 hours) chicken. tumours were observed in 66.7% highly susceptible chickens and in 33.73% of randomly bred chickens. first clinical signs of disease appeared on the 7-9th days after infection. death occurred on the 3-4th days after beginning of the diseas ...19882832019
immunoblotting with polyclonal and monoclonal antibody to avian myeloblastosis protein p27: studies of liver proteins in chickens with erythroblastosis.an antigen detected by complement fixation with polyclonal antibody to avian myeloblastosis virus (amv) antigen p27, appears in the livers of chickens inoculated with avian erythroblastosis virus (aev). it can be demonstrated at the 30,000 dalton (30k) molecular weight level by western immunoblotting of electropherograms of aev infected liver extracts. the 30k protein reacted strongly with this polyclonal antibody but only weakly with a monoclonal antibody to the same viral antigen and possible ...19872836998
avian nephroblastomas induced by a retrovirus (mav-2) lacking oncogene. ii. search for common sites of proviral integration in tumour dna.to demonstrate the existence of a common site of integration in independent tumour clones, restriction mapping of the vicinity of integrated mav-2 proviruses in nephroblastoma dna was performed, using southern hybridization with an mav-2 specific probe u3(pat). the results have shown that (1) nephroblastomas are of semiclonal origin. (2) nephroblastoma cells contain an average of 5 clonally located integrated proviruses per diploid genome; they do not contain any detectable amount of non-integra ...19882849568
dna-binding activity is associated with purified myb proteins from amv and e26 viruses and is temperature-sensitive for e26 ts mutants.oncogene protein products from avian myeloblastosis virus, p48v-myb, and from avian leukemia virus e26, p135gag-myb-ets, are located predominantly in the nucleus of nonproducer bone marrow cell clones, as revealed by indirect immunofluorescence. both oncogene proteins were purified by immunoaffinity chromatography using monoclonal antibodies against p19 and immunoglobulins specific for myb, which was expressed in bacteria for antibody production. the purified proteins bind to dna in vitro. in co ...19852985272
transformation of brown leghorn chicken embryo fibroblasts by avian myeloblastosis virus proviral dna.brown leghorn chicken embryo fibroblasts were transfected with a mixture of avian myeloblastosis virus (amv) and myeloblastosis-associated virus type 1 (mav1) proviral dna purified from lambda-charon 4a recombinant clones. a transformed cell line (t1am) able to grow without anchorage in semisolid medium was obtained. the presence of both proviral amv and mav sequences was detected in t1am dna by hybridization with v-myb- and mav1-specific probes. altered amv and mav1 proviral genomes were found ...19852989555
sites of recombination between the transforming gene of avian myeloblastosis virus and its helper virus.the sites of recombination between the transforming gene of avian myeloblastosis virus (amv) and its natural helper myeloblastosis-associated virus (mav) have been determined. in amv, the cellular sequence substituting for the viral envelope (env) gene gives rise to a different carboxyl terminus of the dna polymerase. the 5'-recombination site coincides with the rna splice acceptor site for the production of env mrna in mav-infected cells. the 3'-recombination site reveals that the last 11 amino ...19852992154
biologically active proviral clone of myeloblastosis-associated virus type 1: implications for the genesis of avian myeloblastosis virus.a biologically active myeloblastosis-associated virus (mav) provirus was cloned from a bacteriophage recombinant library constructed from leukemic chicken myeloblast dna. the restriction endonuclease map of this clone was consistent with that of a type 1 mav (mav-1). interference assays of virus recovered from cultured chicken embryo fibroblasts after dna transfection established that the provirus was infectious and confirmed that it belonged to avian retrovirus subgroup a (type 1). antipeptide ...19852993653
nucleotide sequence of cdna clones of the murine myb proto-oncogene.we have isolated cdna clones of murine c-myb mrna which contain approximately 2.8 kb of the 3.9-kb mrna sequence. nucleotide sequencing has shown that these clones extend both 5' and 3' to sequences homologous to the v-myb oncogenes of avian myeloblastosis virus and avian leukemia virus e26. the sequence contains an open reading frame of 1944 nucleotides, and could encode a protein which is both highly homologous, and of similar size (71 kd), to the chicken c-myb protein. examination of the dedu ...19852998780
characterization of monoclonal antibodies to avian leukosis viruses.hybridoma cell lines secreting monoclonal antibody (mca) to avian leukosis virus (alv) structural proteins p27 and p19 have been established. in an indirect enzyme-linked immunosorbent assay (elisa), mca 6al20 (igg1 isotype) reacted with rpl-40 (alv subgroup a), avian myeloblastosis virus (amv) (a mixture of subgroups a and b), rous-associated virus (rav)-2 (subgroup b), and carr-zilber strain of rous sarcoma virus (cz-rsv) (subgroup d) but not with prague strain of rsv (prc-rsv) (subgroup c) or ...19863015099
the proto-oncogene c-ets is preferentially expressed in lymphoid cells.the transforming sequences of the avian acute leukemia virus, e26, contain two distinct oncogenes, v-mybe and v-ets, fused together. by using a probe containing v-ets sequences, polyadenylated transcripts of the c-ets proto-oncogene were detected in avian tissues; they included a major 7.0-kilobase and a minor 2.0-kilobase species. these c-ets mrnas were detected at high levels only in lymphoid organs and in avian t and b lymphoid cell lines. a similar pattern of c-ets transcription was observed ...19853018492
nuclear compartmentalization of the v-myb oncogene product.nuclei obtained from chicken leukemic myeloblasts transformed by avian myeloblastosis virus were fractionated into various subnuclear compartments, which were then analyzed by specific immunoprecipitation for the presence of the leukemogenic product, p48v-myb, of the viral oncogene. in cells labeled for 30 or 60 min with l-[35s]methionine and in unlabeled exponentially dividing leukemic cells analyzed by western blotting, p48v-myb was detected within the nucleoplasm (29 +/- 9% [standard deviatio ...19853018495
structure of the protein encoded by the chicken proto-oncogene c-myb.the retroviral oncogene v-myb arose by transduction of the chicken proto-oncogene c-myb. we isolated and sequenced cdna that represents the entire coding domain of chicken c-myb. by transcribing the cdna into mrna in vitro and then translating the rna, we were able to document the integrity of the cdna and to identify the codon responsible for initiation of translation from c-myb. two different alleles of v-myb are extant, one in the genome of avian myeloblastosis virus (amv) and the other in th ...19863025608
env-encoded residues are not required for transformation by p48v-myb.the v-myb oncogene of avian myeloblastosis virus induces acute myeloblastic leukemia in chickens and transforms avian myeloid cells in vitro. the protein product of this oncogene, p48v-myb, is partially encoded by the retroviral gag and env genes. we demonstrated that the env-encoded carboxyl terminus of p48v-myb is not required for transformation. our results showed, in addition, that a coding region of c-myb which is not essential for transformation was transduced by avian myeloblastosis virus ...19873027417
expression of a truncated v-myb product in transformed chicken embryo fibroblasts.transformed cells have been isolated after transfection of chicken embryo fibroblasts (cef) with the dna of a recombinant clone (kxa 3457) in which the v-myb sequences are flanked by the two amv-ltrs. abnormal myb-specific rna species and myb-related polypeptides were found to be expressed in these cells, suggesting that transformation of cef by v-myb might require alterations of the oncogene product.19873032682
two exons specific for the myb proto-oncogene found upstream from the avian myeloblastosis virus-transduced myb sequences.a partial restriction map of cloned 5.42-kb chicken dna (clone p542, perbal et al. 1983), covering a portion of the c-myb locus, is presented. the 5' end of the v-myb gene (approximately 0.5 kb) is located at the 3' end of p542 dna, the remainder are the cellular sequences not transduced by avian myeloblastosis virus. two non-contiguous dna segments were detected within these cellular sequences which code for the 5' end of c-myb mrna. these two exons, designated e1 and e2, are separated by a app ...19873032698
antibodies to the evolutionarily conserved amino-terminal region of the v-myb-encoded protein detect the c-myb protein in widely divergent metazoan species.antibodies directed against a bacterial fusion protein that contains the domain encoded by the highly evolutionarily conserved 5' one-third of the v-myb oncogene of avian myeloblastosis virus (amv) detect the protein products of various members of the myb gene family. immunoprecipitation or immunoblot analyses with these antibodies yielded the following information. first, the products of the v-myb oncogenes of amv (p48v-myb) and of e26 virus (p135gag-myb-ets) contain this highly conserved amino ...19863088565
sequential study of visceral lesions caused by isolates of an avian osteopetrosis virus (myeloblastosis-associated virus).ten-day-old chicken embryos were inoculated with isolates of myeloblastosis-associated virus that induced osteopetrosis of slow or rapid onset. bursa of fabricius, thymus, spleen, bone marrow, kidney, liver, and lung were examined at 15, 17, and 19 days in ovo and at 7 and 25 days after hatching by histologic and immunoperoxidase techniques. tissues from 19-day-old in ovo embryos also were examined by electron microscopy. the lymphoid organs of embryos inoculated with all isolates manifested cha ...19883223670
proto-oncogene expression in chicken leukemic cells induced by avian myeloblastosis virus.sixteen proto-oncogenes which have generated retroviral oncogenes were tested for their expression in chicken leukemic cells induced by avian myeloblastosis virus (amv) and five were found to be expressed (c-ets, c-fps, c-mht, c-myc, and c-rel). the size of the c-fps transcript (4.0 kb) was not in good agreement with the size (approximately 3.0 kb) previously reported but was uniform in the leukemic cells from 10 different chickens. the size of the other proto-oncogene transcripts appeared norma ...19883226723
a sequential study of bone lesions caused by isolates of an avian osteopetrosis virus, mav-2(0).the pathogenesis of avian osteopetrosis caused by rapid and slow-onset isolates of myeloblastosis associated virus, mav-2(0), was studied by inoculation of 10-day-old chick embryos with virus. femur and calvarium were examined at 15, 17 and 19 days in ovo and 7 and 25 days after hatching by histologic and immunoperoxidase techniques. femur and calvarium were also examined by electron microscopy at 17 and 19 days in ovo and at 7 days after hatching. avian osteopetrotic bone lesions were character ...19873446259
identification in chicken macrophages of a set of proteins related to, but distinct from, the chicken cellular c-ets-encoded protein p54c-ets.using an antiserum to a bacterially expressed polypeptide corresponding to 56 amino acids of v-ets, we previously identified in chicken tissues a protein of 54 kd (p54c-ets) which shares extensive sequence homology to the v-ets-encoded domain of the e26-transforming protein p135gag-myb-ets and is thus apparently encoded by the c-ets proto-oncogene. we report here that the anti-ets serum specifically identifies in chicken cells a second set of proteins of 60 kd (p60), 62 kd (p62) and 64 kd (p64) ...19863536486
[tumors of the brain vascular plexuses caused by the avian myeloblastosis virus].a series of experiments on the induction of tumours in the central nervous system with the help of avian myeloblastosis virus was carried out. 142 highly sensitive and inbred chickens, 1 or 2 days of age, were used. the intracerebral virus dose was 0.01-0.02 ml. the titer was 10(9)--10(12) pfu/ml. 25 tumours of choroid plexus were induced during the experiments, 3 tumours developed in the control after intravenous inoculation. out of 33 chickens highly sensitive to amv tumours of choroid plexus ...19873620686
nucleotide sequence of chicken c-myb complementary dna and implications for myb oncogene activation.avian myeloblastosis virus (amv), like other acute transforming viruses, arose by recombination between its helper virus and host cellular sequences. the latter sequences, termed v-myb, are responsible for the oncogenic properties of the virus. amv causes acute myeloblastic leukaemia in chickens and transforms a specific class of haematopoietic cells in vitro, but does not induce morphological transformation of cultured fibroblasts, suggesting that only a restricted target-cell population is res ...19863753748
avian monocytic leukemia cells release fibroblast growth factor: implications to associated myelofibrosis.the marrow of chicks with leukemia induced by avian 'myeloblastosis' virus (amv) exhibited a 5-10-fold increase in the number of fibroblast colony-forming cells (cfu-f). the increased cfu-f correlated with a mild fibrosis which can be seen in the marrow of these animals. fibroblast proliferation likely was not simply due to the presence of leukemic cells because addition of formaldehyde-fixed peripheral leukemic cells failed to initiate cfu-f growth. conditioned medium (cm) from day-4 cultures o ...19853866125
[involvement of bone tissue in chicken infected with the myeloblastic mav 2-0 virus. generalized cortical hyperostosis].an affection of osseous tissue appears in chicken have been injected at the embryonic state with retrovirus myeloblastic mav 2-0 in solution. the structural lesions are different from these examined in human or murine osteopetrosis, considered to be an general cortical hyperostosis.19853919885
induction of colony-stimulating factor from quiescent fibroblasts by avian macrophages and monocytic leukemic cells.confluent, quiescent chick embryo fibroblasts maintained in protein-free medium released csf(s) active on granulocyte and monocyte progenitors and on monocytic leukemia cells induced by avian 'myeloblastosis' virus (amv) when exposed to formaldehyde-fixed amv leukemic cells. the csf was assayed under serum-free conditions. of several normal cell types tested including populations enriched for blast cells, only macrophages exhibited this capacity.19853935882
serological analysis of the deoxyribonucleic acid polymerase of avian oncornaviruses. ii. comparison of avian deoxyribonucleic acid polymerases.monospecific antiserum prepared against the isolated deoxyribonucleic acid (dna) polymerase of avian myeloblastosis virus (amv) neutralized the endogenous ribonucleic acid-instructed dna polymerase activity of detergent-disrupted virus. the viral polymerase was serologically unrelated to the seven major structural polypeptides of amv. furthermore, the viral enzyme was distinguished from normal cellular dna polymerases by serological criteria; thus, antiserum against the viral enzyme neutralized ...19724117966
lack of serological relationship among dna polymerases of avian leukosis-sarcoma viruses, reticuloendotheliosis viruses, and chicken cells.antibodies against a large and a small dna polymerase isolated from chicken embryos and against avian myeloblastosis virus dna polymerase were used to study the serological relationships of the dna polymerase activities of three avian systems with rna and a dna polymerase-avian leukosis-sarcoma viruses, reticuloendotheliosis viruses, and a fraction from uninfected chicken cells. the dna polymerase activity of disrupted virions of all avian leukosis-sarcoma viruses tested was neutralized to the s ...19734127028
outer membrane of avian myeloblastosis virus.guinea pigs immunized intracerebrally with avian myeloblastosis virus (amv) produced antiserum which reacted with intact virus particles in complement fixation. the antigen in question appeared to be located on the surface of the virion and could be distinguished from the type-specific virus envelope and the group-specific internal antigens of chicken leukosis-sarcoma viruses (chilsv). the material could be isolated by sequential treatments of amv with bromelin, tween 20, and freeze-thawing, and ...19734128385
Displaying items 1 - 100 of 237