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rnase h-mediated release of the retrovirus rna polyadenylate tail during reverse transcription.by examining enzymatic reactions in vitro, we found that an early event during reverse transcription of the avian myeloblastosis virus rna genome is the release of the 3' polyadenylate tail from the viral rna template. by using specially constructed molecules containing minus-strand, strong-stop dna and the 3' end of the viral rna genome, we found that the reverse transcriptase-associated rnase h is responsible for the endonucleolytic release of polyadenylate.19852578196
inhibition of rna-directed dna polymerase from avian myeloblastosis virus by a 5-benzyl-6-aminouracil.5-(p-chlorobenzyl)-6-aminouracil (5-clau) inhibited rna-dependent dna polymerase (reverse transcriptase) from avian myeloblastosis virus. inhibition was expressed only in the presence of a polyribonucleotide template such as mrna or poly(ra), and kinetic analysis suggested that the action of 5-clau is competitive with template:primer. 5-clau did not inhibit hela dna polymerase gamma, an enzyme that efficiently copies polyribonucleotide templates. a mechanism is proposed in which a 5-clau:templat ...19852578788
2'-fluoro-2'-deoxycytidine triphosphate as a substrate for rna- and dna-dependent dna polymerases.the ability of the analog 2'-fluoro-2'-deoxycytidine triphosphate (dcfltp) to be used as a substrate in the reactions catalyzed by xenopus laevis oocytes dna polymerase alpha and amv reverse transcriptase has been studied. the apparent km values for dctp and dcfltp, using activated dna as templates, were 0.6 microm and 7 mm with dna polymerase alpha and 0.14 microm and 7 microm with amv reverse transcriptase, respectively. as observed with dctp, aphidicolin was a noncompetitive inhibitor in the ...19852578819
2'-fluoro-2'-deoxypolynucleotides as templates and inhibitors for rna- and dna-dependent dna polymerases.poly(2'-fluoro-2'-deoxyadenylic acid) (poly(dafl)) and poly(2'-deoxycytidylic acid) (poly(dcfl)) were tested as templates in dna synthesis reactions catalyzed by xenopus laevis oocytes dna polymerase alpha, mouse cell dna polymerase gamma and avian myeloblastis virus (amv) reverse transcriptase. poly(dafl).(dt)12 can fully substitute for poly(ra).(dt)12 as template with dna polymerase gamma, to 50% with reverse transcriptase, but was poorly recognized by dna polymerase alpha. dna synthesis by re ...19852578820
effect of avian osteopetrosis virus infection on cells and their collagen synthesis in vitro.primary avian tendon fibroblasts and calvarial osteoblasts were infected with the avian osteopetrosis virus mav.2-o, in vitro. the infected tendon cells could be cloned in soft agar and kept in culture for at least 25 passages, a number not reached by uncloned infected cells. in contrast to many other virus-transformed fibroblasts, these cells continued making collagen and fibronectin, and there were no gross morphological changes as observed in the light microscope. changes were seen in their c ...19852579813
serum-free conditions for the growth of avian granulocyte and monocyte clones and primary leukemic cells induced by amv, and the apparent conversion of granulocytic progenitors into monocytic cells by a factor in chicken serum.the supportive activity of chicken serum for the soft-agar growth of chicken granulocyte and monocyte clones could be replaced with defined ingredients [bovine serum albumin (bsa), conalbumin, selenium, linoleic acid and for routine work, a liquid soy lecithin preparation (59% phospholipids, 39% linoleic acid, and less than 2% of inositol and choline)]. the lecithin preparation could be replaced with l-alpha-phosphatidylcholine. the source of colony-stimulating factor was medium conditioned by f ...19852984219
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
cellular transformation by avian viruses. 19852987984
structural characterization of the avian retrovirus reverse transcriptase and endonuclease domains.the enzymatic domains of the avian retrovirus polymerase (pol) gene have been mapped by the use of peptide antibodies and cooh-terminal amino acid analysis. the processed pol beta polypeptide is cleaved in vivo to yield alpha and pp32. rabbit antibodies were directed against synthetic peptides whose sequence was deduced from the known pol sequence of rous sarcoma virus, prague c (schwartz, d.e., tizard, r., and gilbert, w. (1983) cell 32, 853-869). the rnase h active site of pol was located in t ...19852989284
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
developmental and molecular aspects of nephroblastomas induced by avian myeloblastosis-associated virus 2-o.avian myeloblastosis-associated virus-induced nephroblastomas are tumors consisting mainly of mesenchymal and epithelial renal elements with variable degrees of differentiation. the spatial distribution of developmental stages reflects a gradient of differentiation from less differential structures in the periphery towards more differentiated structures in the center of the lobules formed in the nephroblastomas. these heterogenic tumors contain discrete virus-cell dna junction fragments and are ...19852989556
retroviral oncogenes and human neoplasia. 19852990442
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
oncogenes of avian acute leukemia viruses are subsets of normal cellular genes. 19852993114
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
structural organization of the mouse proto-myb gene.proto-myb is a highly conserved cellular gene that is closely related to v-myb, the transforming gene of the avian myeloblastosis virus. we have isolated lambda clones encompassing 21 kbp of mouse dna that contains portions of the proto-myb gene. also, we have isolated a cdna clone containing a 2.5 kbp insert corresponding to mouse proto-myb mrna. by analyzing both the cloned dnas and mouse genome dna, we have constructed a restriction map for mouse proto-myb that extends over 50 kbp.19852998378
poly(dg-dc) in the z-form inhibits e. coli dna polymerase i and amv dna polymerase activity.the effect of z-conformation of dna on its template activity in dna synthesis reactions in vitro has been studied. normal poly(dg-dc) in the b-form, brominated and unbrominated in the z-form have been compared for their template activity in dna synthesis reactions mediated by amv dna polymerase and e. coli dna polymerase i. the results indicate that poly(dg-dc) in the z-form is totally inactive as a template for dna synthesis and further that it is a strong competitive inhibitor of copying of th ...19852998388
enhanced viral inhibition of lymphocyte mitogenesis in patients with advanced breast cancer.virus particles are frequently able to non-specifically inhibit the capacity of human peripheral blood lymphocytes to respond to mitogenic or antigenic stimuli. in the case of breast cancer patients with advanced disease, the quantity of virus required to abrogate responsiveness to phytohaemagglutinin (pha) was approximately four-fold less than that found when cells from healthy donors were employed. the results show that such virus co-incubated cultures are deficient with regard to their abilit ...19852998661
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
detection and localization of the v-myb(amv) gene products of avian myeloblastosis virus by a synthetic peptide antiserum.an antiserum made against a synthetic peptide from an internal region of the predicted amino acid sequence of the avian myeloblastosis virus (amv) transforming v-myb(amv) gene identified two products, p46v-myb(amv) and p32v-myb(amv), which were localized in the nucleus of amv-transformed myeloblasts. we propose that these proteins are the in vivo products of the v-myb(amv) gene and thus the transforming protein(s) of amv.19852999319
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
transformation-defective mutant of avian myeloblastosis virus that is temperature sensitive for production of transforming protein p45v-myb.we have characterized a mutant of avian myeloblastosis virus (strain ga907/7) that shows a reduced capacity to transform myelomonocytic cells at the nonpermissive temperature. myeloblasts transformed by this mutant suffer a substantial decrease in the amount of the transforming protein p45v-myb when shifted from the permissive to the nonpermissive temperature. we presume that the 5- to 10-fold decrease in the amount of p45v-myb causes the loss of the transformed phenotype. the decrease is due to ...19853018515
expression of alfalfa mosaic virus rna 4 cdna transcripts in vitro and in vivo.copies of alfalfa mosaic virus (amv) rna 4 synthesized by transcription in vitro were shown to be biologically active in protoplasts when inoculated together with a mixture of amv rnas 1, 2, and 3. a 5' cap was essential for activity, whereas 15 nonviral nucleotides at the 5' end of the rna transcripts did not detectably affect activity. transcripts that terminated 65 nucleotides from the 3' end of the coding region and transcripts that lacked all or part of the 3'-noncoding region were effectiv ...198518640556
application of monoclonal antibodies in the avian leukosis virus gs-antigen elisa.five hybridoma cell lines which secrete antibodies to avian leukosis/ sarcoma (alv) group-specific (gs) antigens (gag gene products) have been established. the hybrid cells resulted from fusion of p3/x63-ag8.653 myeloma cells with splenocytes of balb/c mice which had been immunised with purified avian myeloblastosis virus (amv). screening of supernatant fluids was performed by an indirect double antibody sandwich enzyme-linked immunosorbent assay (idas-elisa) and the immunoelectroblotting techni ...198518766897
synthesis of double-stranded complementary dna from poly(a)(+)mrna.the use of avian myeloblastosis virus reverse transcriptase (amv rtase) to produce dna copies of mrna templates is a common and well-documented method (1-3). briefly, the method involves synthesis of a complementary dna strand to the mrna from a short double-stranded region, usually provided by using an oligo(dt) primer on poly(a)(+)rna. the enzyme does not always produce full length transcripts, but all the complementary strands are finished off with a short hairpin loop. this provides a ready- ...198521374188
on the fidelity of dna synthesis. pyrophosphate-induced misincorporation allows detection of two proofreading mechanisms.the effect of pyrophosphate on the fidelity of in vitro dna synthesis has been examined. pyrophosphate enhances misincorporation by escherichia coli dna polymerase i in copying phi x174 dna. the increased misincorporation is directly proportional to the extent of inhibition of the rate of polymerization. in contrast, pyrophosphate is not detectably mutagenic with avian myeloblastosis virus dna polymerase or dna polymerases alpha and beta from animal cells, which lack associated proofreading acti ...19863020037
covalently linked sequencing primer linkers (splinkers) for sequence analysis of restriction fragments.a new method for direct sequence analysis of dna restriction fragments uses synthetic covalently linked complementary oligodeoxynucleotides, as universal sequencing primer linkers (splinkers). these splinkers were designed to contain an inverted repeat sequence which forms a double-stranded hairpin structure with a known restriction site. the splinkers were characterized by their ability to be self-ligating (dimerized) and by their restriction digest product analysis of both the monomer and dime ...19863023188
subnuclear localization of proteins encoded by the oncogene v-myb and its cellular homolog c-myb.the retroviral transforming gene v-myb encodes a 45,000-mr nuclear transforming protein (p45v-myb). p45v-myb is a truncated and mutated version of a 75,000-mr protein encoded by the chicken c-myb gene (p75c-myb). like its viral counterpart, p75c-myb is located in the cell nucleus. as a first step in identifying nuclear targets involved in cellular transformation by v-myb and in c-myb function, we determined the subnuclear locations of p45v-myb and p75c-myb. approximately 80 to 90% of the total p ...19863023837
coordinate regulation of myelomonocytic phenotype by v-myb and v-myc.both avian myeloblastosis virus (by the action of v-myb) and avian myelocytomatosis virus mc29 (by the action of v-myc) transform cells of the myelomonocytic lineage. whereas avian myeloblastosis virus elicits a relatively immature phenotype, cells transformed by mc29 resemble mature macrophages. when cells previously transformed by v-myb were superinfected with mc29, their phenotype was rapidly altered to that of a more mature cell. these superinfected cells expressed both v-myb (at a level sim ...19863023905
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
structure and processing of the p2 region of avian sarcoma and leukemia virus gag precursor polyproteins.we have purified two low-molecular-weight polypeptides from the prague c strain of rous sarcoma virus and have identified these as products of the gag precursor pr76 by protein sequencing and by amino acid analysis. both polypeptides are derived from a stretch of 22 amino acids within pr76 that separates p19 and p10. we refer to this region as p2. together the two cleavage products form the entire p2 region. the junctions of p19 with the amino-terminal fragment of p2 and of p10 with the carboxy- ...19863005658
a cryptic transcription promoter in the myb oncogene of avian myeloblastosis virus.the potential regulatory signals contained in the v-myb oncogene of avian myeloblastosis virus have been inserted upstream to the herpes simplex type 1 thymidine kinase gene in order to test their promoter activity. the isolation of tk+ transformants after transfection of clone 1d(tk-) mouse cells with the resulting recombinant dnas indicated that the expression of the tk gene was made possible by the myb-derived sequences. analysis of the tk specific rna expressed in different tk+ transformants ...19863006338
nuclease mechanism of the avian retrovirus pp32 endonuclease.in vivo, the inferred circular retrovirus dna precursor to the provirus contains two long terminal repeats (ltrs) in tandem. we studied the site-specific nicking of supercoiled dna that contains tandem copies of avian retrovirus ltr dna in vitro by using purified avian myeloblastosis virus pp32 endonuclease, mg2+, and viral dna substrates containing different ltr circle junction sequences. the results confirmed our previous observation that the pp32 protein generates two nicks, one in either vir ...19863009900
identification of a provirally activated c-ha-ras oncogene in an avian nephroblastoma via a novel procedure: cdna cloning of a chimaeric viral-host transcript.retrovirus without oncogenes often exert their neoplastic potential as insertional mutagens of cellular proto-oncogenes. this may be associated with the production of chimaeric viral-host transcripts; in these cases; activated cellular genes can be identified by obtaining cdna clones of bipartite rnas. this approach was used in the analysis of chicken nephroblastomas induced by myeloblastosis-associated virus (mav). one tumor contained a novel mrna species initiated within a mav ltr. cdna clonin ...19863011401
studies of the human c-myb gene and its product in human acute leukemias.the myb gene is the transforming oncogene of the avian myeloblastosis virus (amv); its normal cellular homolog, c-myb, is conserved across a broad span of evolution. in humans, c-myb is expressed in malignant hematopoietic cell lines and in primary hematopoietic tumors. partial complementary dna clones were generated from blast cells of patients with acute myelogenous leukemia. the sequences of the clones were compared to the c-myb of other species, as well as the v-myb of amv. in addition, the ...19863014652
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
expression of molecular clones of v-myb in avian and mammalian cells independently of transformation.we demonstrated that molecular clones of the v-myb oncogene of avian myeloblastosis virus (amv) can direct the synthesis of p48v-myb both in avian and mammalian cells which are not targets for transformation by amv. to accomplish this, we constructed dominantly selectable avian leukosis virus derivatives which efficiently coexpress the protein products of the tn5 neo gene and the v-myb oncogene. the use of chemically transformed qt6 quail cells for proviral dna transfection or retroviral infecti ...19863016296
structural organization and nucleotide sequence of mouse c-myb oncogene: activation in abpl tumors is due to viral integration in an intron which results in the deletion of the 5' coding sequences.bacteriophage libraries of mouse dna were screened for sequences homologous to the v-myb oncogene and two overlapping clones containing the v-myb related region were isolated. restriction enzyme mapping, heteroduplex analysis and nucleotide sequence analysis revealed the presence of nine exons. six of these exons are homologous to the v-myb region while the other three exons are derived from the 5' region which is deleted in the viral oncogene. the sequences downstream to the sixth v-myb exon ar ...19863016644
functional studies on the egf receptor with an antibody that recognizes the intracellular portion of the receptor.an antibody against the human epidermal growth factor receptor (egf), capable of activating its tyrosine kinase has been produced. antibody 2913 recognizes only the cytoplasmic portion of the egf receptor in a431 carcinoma cells, in normal human fibroblasts, and in a variety of other human tumor cell lines (xu, y.-a., richert, n., ito, s., merlino, g. t., and pastan, i. (1984) proc. natl. acad. sci. u. s. a. 81, 7308-7313). indirect immunofluorescence and electron microscopy show that the antibo ...19862418017
biological properties of streptonigrin derivatives. ii. inhibition of reverse transcriptase activity. 19862420775
inhibition by sakyomicin a of avian myeloblastosis virus reverse transcriptase and proliferation of aids-associated virus (htlv-iii/lav).in the course of screening for inhibitors of reverse transcriptase, we have isolated an inhibitor from a strain of nocardia and identified it as sakyomicin a. the antibiotic blocks avian myeloblastosis virus reverse transcriptase reaction: ic50 was ca. 30 micrograms/ml by the method employed. the drug affects proliferation of htlv-iii/lav in htlv-i-carrying mt-4 cells: ca. 60% inhibition was observed at an antibiotic concentration of 1.0 microgram/ml and ca. 20% inhibition at 0.1 microgram/ml, a ...19862422146
role of the naphthoquinone moiety in the biological activities of sakyomicin a.the naphthoquinone moiety was proven to be essential to the biological activities of sakyomicin a using various naphthoquinone derivatives. among the naphthoquinones tested, juglone (5-hydroxy-1,4-naphthoquinone) which resembles the partial structure of sakyomicin a was the most active in cytotoxicity against murine lymphosarcoma l5178y cells, electron acceptor function in the oxidation of nadh by clostridium kluyveri diaphorase or rat liver mitochondria and inhibition against avian myeloblastos ...19862423491
differential effects of captan on dna polymerase and ribonuclease h activities of avian myeloblastosis virus reverse transcriptase.captan was used as an inhibitor of avian myeloblastosis virus reverse transcriptase to study the polymerase and rnase h catalytic activities. with purified enzyme, rnase h activity was 10-fold more sensitive to captan than was either the dna-dependent or rna-dependent dna polymerase activity. inhibition of the rna-dependent polymerase activity could be prevented by dttp. conversely, inhibition of this polymerase activity was enhanced by template/primer. the calculated kdttp of the uninhibited re ...19862424494
mapping of the displacement loop within the nucleotide sequence of xenopus laevis mitochondrial dna.the mtdna of the african frog, xenopus laevis, has a triple-stranded displacement loop (d-loop) structure at the origin of heavy strand dna replication. the major species of displacing strands has a length of 1670 nucleotides, approximately 3 times the length of mouse or human d-loop mtdna strands. we report experiments that precisely map the termini of the d-loop strand within a revised sequence of the origin region. analysis of d-loop mtdna strands labeled in vitro at the 5' end using polynucl ...19862424898
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
ppi analogs as inhibitors of human t-lymphotropic virus type iii reverse transcriptase.twenty-six ppi analogs were tested for inhibitory effects on human t-lymphotropic virus type iii reverse transcriptase. the structural requirements for inhibition and mechanism of action of the most active inhibitors have been investigated. foscarnet (phosphonoformic acid) was the most potent inhibitor of human t-lymphotropic virus type iii reverse transcriptase with 50% inhibition at 0.5 microm. the mechanism was a noncompetitive type of inhibition of a (riboadenylic acid)n . (deoxythymidylic a ...19862425731
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
characterization, sequence, and expression of the cloned human neuropeptide y gene.the human neuropeptide y (npy) gene was isolated from a human genomic dna library. the transcription unit spans approximately 8 kilobase pairs and is interrupted by three intervening sequences. the first exon contains only nontranslated dna. the site where transcription initiates was determined by primer extension analysis using a primer derived from a human cdna, pheochromocytoma rna and avian myeloblastosis virus reverse transcriptase. a tata-like sequence and a caat-like sequence occur 25 and ...19862427515
misincorporation by amv reverse transcriptase shows strong dependence on the combination of template and substrate nucleotides.we have carried out a systematic investigation of the efficiency of misincorporation by avian myeloblastosis virus reverse transcriptase with all possible combinations of dntp substrate, template nucleotide, and the nucleotide at the 3' terminus of the primer. a series of synthetic oligonucleotide primers were annealed to single stranded m13 dna templates, and a single dntp was misincorporated at the primer 3' end using amv reverse transcriptase. the proportion and pattern of misincorporation an ...19862429257
nucleoside 5'-triphosphates modified at sugar residues as substrates for calf thymus terminal deoxynucleotidyl transferase and for amv reverse transcriptase.terminal deoxynucleotidyl transferase from calf thymus and rna-directed dna polymerase (reverse transcriptase) from the avian myeloblastosis virus catalyze the incorporation of 3'-amino-2',3'-dideoxynucleoside 5'-triphosphates, as well as some of their 3'-derivatives, 3'-amino-3'-deoxyarabinonucleoside 5'-triphosphates and some other nucleoside 5'-triphosphates modified at sugar residues. after incorporation of the appropriate 5'-mononucleotide residue into the dna, further chain elongation is b ...19862429703
direct identification of small sequence changes in chromosomal dna.dideoxynucleotide chain termination sequencing has been applied directly to genomic dna templates by annealing radiolabeled oligodeoxynucleotide primers to unique sites in total yeast dna and extending with avian myoblastosis virus (amv) reverse transcriptase. the technique is used here to confirm the introduction of selectively altered trna genes into the saccharomyces cerevisiae genome by gene replacement.19862429900
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
fluorescence studies on the coat protein of alfalfa mosaic virus.the intrinsic luminescence of different forms of the alfalfa mosaic virus (amv) strain 425 coat protein has been studied, both statically and time resolved. it was found that the emission of the protein (mr 24,250), which contains two tryptophans at positions 54 and 190 and four tyrosines, is completely dominated by tryptophan fluorescence. the high fluorescence quantum yield indicates that both tryptophans are emitting. surprisingly, the fluorescence decay is found to be strictly exponential, w ...19863271050
the myb oncogene.the highly conserved, single copy c-myb gene has been independently transduced by two avian acute leukemia viruses, amv and e26. this gene has also undergone insertional mutagenesis by non-acutely transforming murine leukemia viruses in a number of hematopoietic tumors. the common denominator of these retroviral activations of c-myb appears to be truncation of the normal coding region at either or both ends. the role of point mutations in myb-induced leukemogenesis is currently unknown. the prod ...19863333362
structure and mechanism of activation of the myb oncogene.the results summarized in this review show that the normal chicken myb gene codes for a protein of 77 kd which appears to play an important role in the control and/or differentiation of hematopoietic cells of myeloid and t lymphoid series. the activation of this gene has been observed in chicken and murine systems. in the avian system, this has been achieved by transduction of the myb oncogene into a retrovirus. such a transduction resulted in the deletion of coding sequences from both the 5' an ...19863333363
identification of c-myb (chicken), c-myb (mouse) and v-myb (amv) protein products by immunoprecipitation with antibodies directed against a synthetic peptide.a synthetic nonadecapeptide (il 19) derived from a sequence of v-myb was covalently bound to haemocyanin and used for immunization. anti-il 19 serum immunoprecipitated a 75 kda protein in the lysate of metabolically labelled chicken and murine thymus cells. presaturation of the serum with il 19 abolished this immunoprecipitation, thus indicating that the product of c-myb in both chicken and murine thymuses is the 75 kda protein (p75c-myb). anti il 19 serum also precipitated p48v-myb in the lysat ...19863527747
identification and characterization of the protein encoded by the human c-myb proto-oncogene.we have identified the product of the human c-myb proto-oncogene as a 80,000-mr protein, p80c-myb, by using polyclonal and monoclonal antibodies raised against a bacterially synthesized polypeptide from the amino terminus of the viral myb protein. p80c-myb shares at least two distinct antigenic sites with the amino terminal region of the v-myb protein. p80c-myb is found only in hematopoietic cells or in cells that contain amplified c-myb genes. like the chicken myb proteins, p80c-myb is a nuclea ...19863530745
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
protein product of proto-oncogene c-mil.using antipeptide antibodies with specificity for the carboxyl termini of v-raf and v-mil protein products, two proteins with apparent molecular weights of approximately 71,000/73,000 and 215,000 were detected in immunoprecipitates from normal uninfected chicken cells. the 71,000/73,000-molecular-weight protein was identified as the product of the c-mil proto-oncogene by the close structural relationship of its 42,000-molecular-weight carboxyl-terminal domain to the v-mil-encoded domain of the h ...19863537695
sequence-specific dna-binding proteins which interact with (g + c)-rich sequences flanking the chicken c-myc gene.the interaction of nuclear sequence-specific dna-binding proteins from definitive chicken erythrocytes, thymus and proliferating transformed erythroid precursor (hd3) cells with the 700-base-pair (700-bp) dna 5'-flanking region of the chicken c-myc gene was investigated by in vitro footprint analysis. the major hd3 protein-binding activity binds to a site (site v) 200 bp upstream from the 'cap' site but, after further fractionation, a second distinct binding activity is detected to a site (site ...19863743569
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
template-selective stimulation of diverse dna polymerases by the murine dna-binding protein factor d.factor d, a template-selective dna polymerase-alpha stimulatory protein from mouse liver (fry, m., lapidot, j., and weisman-shomer, p. (1985) biochemistry 24, 7549-7556) is shown here to enhance the activities of diverse dna polymerases with a cognate template specificity. dna synthesis catalyzed by escherichia coli dna polymerase i, avian myeloblastosis virus polymerase, and some mammalian alpha- and gamma-polymerases was increased by factor d. with every enhanced polymerase, factor d increased ...19873597397
[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
subnuclear associations of the v-myb oncogene product and actin are dependent on ionic strength during nuclear isolation.the method used to isolate nuclei has a direct effect on the subnuclear association of the v-myb product, p48v-myb, and nuclear actin. analysis of nuclei subjected to various isolation procedures showed that disruption of native nuclear structure during hypotonic treatment resulted in dissociation of p48v-myb from the nuclear matrix.19873670313
insulin-like growth factor i induces c-fos messenger ribonucleic acid in l6 rat skeletal muscle cells.insulin-like growth factor i (igf-i) mediates growth promotion of gh on specific target cells. as other growth factor action has been associated with oncogene induction, we examined whether igf-i activated cellular oncogenes in l6 rat muscle cells, known target cells of igf-i stimulatory action. quiescent cells were incubated in serum-free defined medium with igf-i (amgen recombinant analog, thr59) from 5 min to 4 h. 32p-labeled dna was first prepared from igf-i-treated cell poly(a) rna using av ...19873536454
[a new terminator of dna biosynthesis--possible conformation analog of the substrate in a dna-synthesizing complex].2',3'-dideoxy-2',3'-dehydrothymidine 5'-triphosphate (dddttp) reveals the termination substrate properties in the dna synthesis catalyzed by e. coli polymerase i (klenow fragment), rat liver dna polymerase beta, calf thymus terminal deoxynucleotidyl transferase, and reverse transcriptase of avian myeloblastosis virus but does not affect calf thymus dna polymerase alpha. for dna polymerase i, dddttp by an order of magnitude is more effective than any known termination substrate. it is supposed th ...19873435558
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
enhanced translation of chimaeric messenger rnas containing a plant viral untranslated leader sequence.eukaryotic messenger rnas are translated with unequal efficiencies in vivo and in vitro and the molecular basis of this phenomenon is not understood. as an approach to understanding the role of the 5' untranslated leader sequence in regulating mrna translational efficiency, chimaeric mrnas have been generated by joining a heterologous leader to complementary dna (cdna) sequences, followed by in vitro transcription using sp6 rna polymerase and in vitro protein synthesis. we used the untranslated ...19873492677
some aspects of dna polymerase functioning.the group of dna polymerases was studied using some new nucleoside 5'-triphosphate analogs with termination substrate properties. among dna polymerases tested the least specific appeared reverse transcriptases of retroviruses and the most specific were dna polymerases alpha type from high eucaryotes including mammalians.19873320974
mechanism of activation of the myb oncogene in myeloid leukemias. 19873326465
rna-dependent dna polymerase activity in paramecium tetraurelia: what for?protein extracts from the protozoan ciliate paramecium tetraurelia revealed high levels of rna-dependent dna polymerase activity (reverse transcriptase). stable and constant during the somatic phase of the cell cycle, the reverse transcriptase activity quickly diminished following the completion of the sexual phases of the cell cycle: conjugation and autogamy. the paramecium reverse transcriptase presented a number of common features with retroviral polymerases: ability to copy synthetic templat ...19872435548
screening for inhibitors of avian myeloblastosis virus reverse transcriptase and effect on the replication of aids-virus. 19872435692
inhibition by doxorubicin of human immuno-deficiency virus (hiv) infection and replication in vitro. 19872437093
inhibition of viral reverse transcriptase by 2',5'-oligoadenylates.viral reverse transcriptase activity was inhibited in a concentration dependent manner by 2',5'-oligoadenylate. kinetically this inhibition was of a mixed type where 2',5'-oligoadenylate was not strictly competitive with dttp. the potency of inhibition was more marked in the absence than in the presence of sulfhydryl agents. 2',5'-oligoadenylate had no effect on dna-dependent e. coli dna polymerase and was much less active against mammalian dna polymerases. this is the first report of reverse tr ...19872439079
properties of 2',3'-dideoxy-2',3'-dehydrothymidine 5'-triphosphate in terminating dna synthesis catalyzed by several different dna polymerases.2',3'-dideoxy-2',3'-dehydrothymidine 5'-triphosphate (dddttp) shows termination substrate properties in the dna synthesis catalyzed by e. coli dna polymerase i kf, rat liver dna polymerase beta, reverse transcriptases of avian myeloblastosis virus and raus sarcoma virus and calf thymus terminal deoxynucleotidyl transferase. this implies that the mononucleotide residue of dddttp incorporates into 3'-termini of newly synthesized dna chains. however, dddttp has no influence on the dna synthesis cat ...19872439382
monoclonal antibodies against rna-dependent dna polymerase from myeloblastosis-associated viruses.two lines of hybridomas, rt-12 and rt-14, secreting monoclonal antibodies against the reverse transcriptase from myeloblastosis-associated viruses have been prepared. the monoclonal antibodies rt-12 and rt-14 specifically react with reverse transcriptase, as has been shown by radioimmunoassay and enzyme-linked immunoassay techniques after sds-page and blotting to nitrocellulose membranes. it has been shown that antigenic determinants for rt-12 and rt-14 are stable to sds denaturation, hence they ...19872439388
different patterns of inhibition of avian myeloblastosis virus reverse transcriptase activity by 3'-azido-3'-deoxythymidine 5'-triphosphate and its threo isomer.the two isomers 3'-azido-3'-deoxythymidine 5'-triphosphate (erythro-azt-tp) and 1-(3'-azido-2',3'-dideoxy-beta-d-xylofuranosyl)thymine 5'-triphosphate (threo-azt-tp) were studied as inhibitors of the reverse transcriptase activity of avian myelobastosis virus. kinetic analysis of the (ra)n x (dt)12-18 (a standard template primer complex of polyriboadenylate and oligodeoxythymidylate of indicated length)-directed reaction revealed that erythro-azt-tp was a competitive inhibitor with respect to dt ...19872440379
comparative study on biological activities of heterocyclic quinones and streptonigrin.thirteen heterocyclic quinones (5 quinoline quinones, 7 isoquinoline quinones, 1 indole quinone) were tested for their effects on avian myeloblastosis virus reverse transcriptase, growth of murine lymphoblastoma l5178y cells, respiration of rat liver mitochondria and oxidation of nadh by clostridium kluyveri diaphorase in comparison with those of streptonigrin, in which the quinoline quinone moiety is considered to play a crucial role. most of the quinoline quinones and isoquinoline quinones inh ...19872440840
role of single-electron reduction potential in inhibition of reverse transcriptase by streptonigrin and sakyomicin a. 19872440841
oligodeoxynucleotides containing synthetic abasic sites. model substrates for dna polymerases and apurinic/apyrimidinic endonucleases.a synthetic procedure has been developed by which stable abasic sites are introduced into oligodeoxynucleotides at any desired position in the sequence. a modified tetrahydrofuran moiety, isosteric with 2'-deoxyribofuranose, serves as a structural analog of the natural apurinic/apyrimidinic site. we have also prepared oligodeoxynucleotides that lack cyclic structure at the abasic site but retain the carbon atoms of the phosphodiester backbone. these synthetic oligodeoxynucleotides are cleaved on ...19872440861
dna damage at thymine n-3 abolishes base-pairing capacity during dna synthesis.3-methylthymine was synthesized into dna copolymers and deoxynucleoside triphosphate to study its effect on dna synthesis by the klenow fragment of escherichia coli polymerase i and avian myeloblastosis virus reverse transcriptase. both polymerases were greatly inhibited by template 3-methylthymine. in response to 3-methylthymine, misincorporation of dttp increased slightly, but occurred only at low levels consistent with spontaneous misincorporation in vitro. surprisingly, template 3-methylthym ...19872442169
antiretroviral activity in a marine red alga: reverse transcriptase inhibition by an aqueous extract of schizymenia pacifica.an aqueous extract from the marine red alga, schizymenia pacifica has been tested in a cell free system for its effect on reverse transcriptase from avian retrovirus (avian myeloblastosis virus), and mammalian retrovirus (rauscher murine leukemia virus). the extract inhibited reverse transcriptase from both these retroviruses but showed almost no effect, if any, on the activity of cellular dna polymerase alpha and rna polymerase ii in vitro. consequently it is unlikely to have an adverse effect ...19872442171
synthesis and application of derivatizable oligonucleotides.to investigate protein-dna interactions, we have synthesized a versatile phthalimide-protected 5-(3-aminopropyl)-2'-deoxyuridine nucleoside probe. the modified residue was incorporated into deoxyoligonucleotides by automated synthesis. the standard oligonucleotide workup also exposed the pendent amino group, which was found to react with either fluorescent labelling agents or, as detailed below, a photoactivatable cross-linking agent. in the dark, a strand with a photolabile group adjacent to th ...19872442728
a system for rapid dna sequencing with fluorescent chain-terminating dideoxynucleotides.a dna sequencing system based on the use of a novel set of four chain-terminating dideoxynucleotides, each carrying a different chemically tuned succinylfluorescein dye distinguished by its fluorescent emission is described. avian myeloblastosis virus reverse transcriptase is used in a modified dideoxy dna sequencing protocol to produce a complete set of fluorescence-tagged fragments in one reaction mixture. these dna fragments are resolved by polyacrylamide gel electrophoresis in one sequencing ...19872443975
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
[ability of 3'-substituted nucleoside phosphothioates to terminate dna synthesis catalyzed by various dna-polymerases].ability of some new substrates containing the 5'-alpha-thiotriphosphate residue to terminate the dna synthesis catalyzed by several dna polymerases has been investigated. the cell-free test system contained the m13mp10 phage single-stranded dna and a synthetic oligonucleotide primer. reverse transcriptase from avian myeloblastosis virus catalyzed termination of dna synthesis by 3'-azido-3'-fluoro- and 3'-amino-2',3'-dideoxythymidine-5'-(alpha-thio)triphosphates, whereas rat liver dna polymerase ...19872445356
sulfation of polysaccharides generates potent and selective inhibitors of human immunodeficiency virus infection and replication in vitro.the inhibitory effects of several polysaccharides, dextran, xylofuranan, and ribofuranan, and their sulfated counterparts on the infectivity and replication of human immunodeficiency virus (hiv) were examined by using an htlv-i-carrying cell line, mt-4, in vitro. dextran sulfate (mw 34 x 10(3], xylofuranan sulfate, and ribofuranan sulfate completely prevented hiv-induced cytopathic effects (cpe) at concentrations greater than 10 micrograms/ml and dextran sulfate (mw 7 x 10(3] at concentrations g ...19872447045
hemin inhibits virion-associated reverse transcriptase of murine leukemia virus.the virion-associated reverse transcriptase activity of rauscher murine leukemia virus was inhibited by freshly prepared hemin at a concentration of 10(-4) m. when the hemin solution was aged at room temperature for 5 days, the concentration of 50% inhibition decreased to as low as 10(-7) m. removal of o2 from the solution partially prevented the aging. the hemin inhibition was reversible and appears to be directed against the enzyme rather than the template. hemin did not inhibit the activity o ...19872447881
purification and characterization of an avian myeloblastosis and human immunodeficiency virus reverse transcriptase inhibitor, sulfated polysaccharides extracted from sea algae.a new reverse transcriptase (rt) inhibitor was extracted and purified from the red alga schizymenia pacifica. the chromatographic behavior and chemical properties of this sea algal extract (sae) suggest that it is a sulfated polysaccharide having a molecular weight of approximately 2,000,000. sae is composed of galactose (73%), sulfonate (20%), and 3,6-anhydrogalactose (0.65%). sae is a member of the lambda-carrageenan family, based on its infrared spectrum and products of hydrolysis. sae select ...19872449120
inhibition of avian myeloblastosis virus reverse transcriptase and its associated activities by daunomycin and adriamycin. 19872452786
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
characterization of a virus-specific proteolytic activity processing the gag precursor of the simian sarcoma-associated virus.the proteolytic processing of the gag precursor polypeptide pr65gag of simian sarcoma-associated virus (ssav) has been studied in vivo and in vitro. in ssav-infected cells (i.e., in vivo) proteins of 52 and 38 kda and the viral protein p30 could be immunoprecipitated with anti-p30 serum. this cleavage pattern is only in part imitated by in vitro cleavage of the isolated pr65gag with avian myeloblastosis virus (amv) protease p15. however, in vitro incubation of isolated pr65gag with detergent-dis ...19873027976
myb-specific probes. 19873029704
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
v-myb does not prevent the expression of c-myb in avian erythroblasts.the v-myb oncogene of avian myeloblastosis virus transforms myeloid cells exclusively, both in vivo and in vitro. the c-myb proto-oncogene from which v-myb arose is expressed at relatively high levels in immature hematopoietic cells of the lymphoid, erythroid, and myeloid lineages but not in myeloblasts transformed by v-myb. this finding suggested that the nuclear v-myb gene product p48v-myb might act directly to inhibit the normal expression of the c-myb gene. i have therefore used a selectable ...19873041047
human monoclonal antibodies derived from lymph nodes of a patient with breast carcinoma react with mumtv polypeptides.nine human hybridoma cell lines were established from a fusion of axillary lymph node lymphocytes of a patient with breast ductal carcinoma with a human lymphoblastoid cell line. the human hybridoma nature of the fusion products was confirmed by chromosomal analysis and hla typing. the hybridomas are stable over a year of growth, and can be frozen, thawed and regrown. the carcinoma cells of the patient harbor mouse mammary tumor virus (mumtv) cross-reacting antigens. the patient's serum and the ...19873024800
[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
inhibition of retroviral protease activity by an aspartyl proteinase inhibitor.retrovirus protease is an enzyme that cleaves gag and gag-pol precursor polyproteins into the functional proteins of mature virus particles. the correct processing of precursor polyproteins is necessary for the infectivity of virus particles: in vitro mutagenesis which introduces deletions into the murine leukaemia virus genome produces a protease-defective virus of immature core form and lacking infectivity. a therapeutic drug effective against disease caused by retrovirus proliferation could l ...19872821409
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