Publications

purification and characterization of the dna polymerase and rnase h activities in moloney murine sarcoma-leukemia virus.	two rnase h (rna-dna hybrid ribonucleotidohydrolase, ec 3.1.4.34) activities separable by sephadex g-100 gel filtration were identified in lysates of moloney murine sarcoma-leukemia virus (msv). the larger enzyme, which we have called rnase h-i, represented about 10% of the rnase h activity in the virion. rnase h-i (i) copurified with rna-directed dna polymerase from the virus, (ii) had a sedimentation coefficient of 4.4s (corresponds to an apparent mol wt of 70,000), (iii) required mn-2+ (2 mm ...	1975	46924
studies on reverse transcriptase of rna tumor viruses iii. properties of purified moloney murine leukemia virus dna polymerase and associated rnase h.	dna polymerase was purified from a cloned isolate of moloney murine leukemia virus (m-mulv). purified m-mulv dna polymerase, upon analysis by polyacrylamide gel electrophoresis, showed one major polypeptide of mol wt 80,000. estimation of molecular weight from the sedimentation rate of the purifed enzyme in a glycerol gradient was consistent with a structure containing one polypeptide. m-mulv dna polymerase could transcribe ribopolymers, deoxyribopolymers, and heteropolymers as efficiently as di ...	1975	46925
full length and discrete partial reverse transcripts of globin and chorion mrnas.	rabbit globin mrna was copied by amv reverse transcriptase in the presence of various concentrations of deoxyribonucleotides (dntps). the cdnas were analyzed by electrophoresis under denaturing conditions in formamide-polyacrylamide gels. discrete size products were detected, ranging from 65 to 650 nucleotides-that is, up to the full length of the mrna template. increasing the concentrations of all four dntps stimulated formation of full-length transcripts and made the incomplete copies less abu ...	1975	47272
inhibition of rna-dependent dna polymerase of oncorna viruses by carbopol 934.		1975	47299
control of transcription of the globin gene.	this report provides a more rigorous proof of previous findings that the rna transcribed in vitro from the chromatins of different organs shows different sequence specificities. here the particular case of the globin gene is considered for a comparison of embryonic mouse liver chromatin and mouse brain chromatin using the reverse transcriptase cdna copy of globin 9s m rna as a definitive probe. it can be shown that globin sequences are transcribed in vitro from embryonic liver chromatin and not ...	1975	47332
complexity of cytoplasmic rna in different mouse tissues measured by hybridization of polyadenylated rna to complementary dna.	the kinetics of hybridization of polyadenylated rna from mouse l-cells with complementary dna (cdna) synthesized with reverse transcriptase revealed three classes of differing abundance. the simplest interpretation requires three frequency classes representing polyadenylated rna; 5, 45, and 50 percent of the total polyadenylated rna and about 3, 300, and 7600 different rna sequences of 6 times 10-5 daltons, respectively. the complementary dna synthesized with l-cell polyadenylated rna as templat ...	1975	47757
unique and repetitive sequences in multiple genes for feather keratin.	embryonic chick feather keratins are a family of homologous polypeptide chains. the mrna coding for these has been obtained in a pure state and transcribed into complementary dna (cdna) using the reverse transcriptase from avian myeloblastosis virus. studies on the kinetics of hybridisation and reannealing of cdna indicate that there are 25-35 different keratin mrna species in the embryonic chick feather, and a total of 100-240 keratin genes in the chick genome. each keratin gene contains both a ...	1975	48196
synthesis of dna complementary to separated human alpha and beta globin messenger rnas.	human globulin messenger rna, purified by oligo(dt)-cellulose column chromatography, is reproducibly separated into two bands by polyacrylamide gel electrophoresis in the presence of 99% formamide. the more rapidly migrating (fast) band is somewhat more abundant than the slow band in normal (nonthalassemic) total reticulocyte globin messenger rna. in alpha-thalassemic (hb h disease) messenger rna, the slow band is 6.5 times more abundant than the fast band, whereas in beta-thalassemic messenger ...	1975	48254
the binding of polynucleotides to the dna polymerase of avian myeloblastosis virus.		1975	48357
inhibition of reverse transcriptase activity of rna-tumor viruses by fagaronine+.		1975	48379
quantitation of avian rna tumor virus reverse transcriptase by radioimmunoassay.	a radioimmunoassay was developed that can detect and quantitate 3 ng or more of the avian rna tumor virus reverse transcriptase. the assay detected no antigenic sites in rous sarcoma virus alpha virions or in virions of a murine rna tumor virus. about 70 molecules of reverse transcriptase were found per virion of avian myleloblastosis virus with this assay or with an assay based on antibody inhibition of enzymatic activity. the assay detected about 270 ng of enzyme per mg of cell protein in viru ...	1975	48558
analysis of antigenic determinants of structural polypeptides of avian type c tumor viruses.	radioimmunoassays were developed for the 19,000, 15,000, and 12,000 molecular weight polypeptides of avian myeloblastosis virus and for the 19,000 and 12,000 polypeptides of rav-0, a subgroup e avian tumor virus. each polypeptide was shown to possess both group- and type-specific antigenic determinants, in contrast to the 27,000 mol wt polypeptide, which contained only group-specific determinants. the corresponding low-molecular-weight polypeptides of subgroup a, b, and e viruses were shown to b ...	1975	48560
ability of tryptophan trna to hybridize with 35s rna of avian myeloblastosis virus and to prime reverse transcription in vitro.	selected species of 4s rna of chick embryo cells will hybridize in vitro with 35s rna of avian myeloblastosis virus. a major trna component of the hybridizable 4s rna is tryptophan trna. a hybrid prepared from purified tryptophan tran and 35s rna of avian myeloblastosis virus in vitro is an efficient templateprimer for dna synthesis catalyzed by reverse transcriptase (rna-dependent dna polymerase).	1975	49054
human globin gene analysis for a patient with beta-o/delta beta-thalassemia.	complementary dna (cdna) was prepared with rna-dependent dna polymerase from human globin messenger rna (mrna). annealing and translation experimenta with total mrna from circulating cells from a patient with heterozygous beta/heterozygous beta-delta-o thalassemia (beta-o/delta beta-o-thalassemia) demonstrated no detectable mrna for beta-globin. cdna enriched in sequences homologous to beta-globin mrna was prepared by hydroxylapatite fractionation of hybrids formed between beta-o/delta beta-o-th ...	1975	49057
immunological properties of avian oncornavirus polypeptides.		1975	49120
the initial nucleotide sequence of dna transcribed from avian myeloblastosis virus 70 s rna by rna-dependent dna polymerase.		1975	49976
microwave excitation emission spectrometry. determination of picogram quantities of metals in metalloenzymes.		1975	50024
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 ...	1975	50081
sequence relatedness between the subunits of avian myeloblastosis virus reverse transcriptase.	one- and two-diminsional tryptic and chymotryptic peptide maps of 125-i-labeled alpha and alphabeta avian myeloblastosis virus dna polymerase demonstrate that the alpha polypeptide of the one and two subunit enzymes are structurally similar, if not identical. furthermore, the beta subunit contains the same major 125i-labeled peptides as alpha, plus several additional peptides. these relationships and the fact that aging of purified alphabeta avian myeloblastosis virus dna polymerase increases th ...	1975	50321
hybridization of pigeon globin messenger rna with complementary dna synthesized in vitro by reverse transcription: influence of the homopolymeric regions.	the kinetics of hybridization of pigeon globin messenger rna with complementary cdna synthesized by means of amv reverse transcriptase is complex. addition of poly a or poly u in excess to the reaction mixture normalized the kinetics. it is concluded that association of the complementary homopolymeric regions of mrna and cdna accelerates the complex formation between heteropolymeric sequences in a fraction of the molecules.	1975	50588
effect of bleomycin on an rna-dna hybrid.		1975	50843
role of the subunits of the avian rna tumor virus reverse transcriptase.		1975	50898
reverse transcriptase and rnase h: present in a murine virus and in both subunits of an avian virus.		1975	50901
properties of oncornavirus rna-directed dna polymerase, the rna template, and the intracellular products formed early during infection and cell transformation.	we have investigated three aspects of rna turmor virus replication and cell transformation: (1) the properties of the purified avian and mammalian viral rna-directed dna polumerase, (2) some characteristics of the viral 60-70s rna genome, 30-40s rna subunits and intracellular viral rna species, and (3) the interaction of the viral dna polymerase with its rna template early during infection and cell transformation by the murine sarcoma-leukemia virus (msv[mlv]). avian myeloblastosis virus (amv) c ...	1975	50902
inhibition of purified dna polymerase of rna tumor viruses by fluoranthene derivatives and analogues of tilorone hydrochloride.	at concentrations of 7 times 10(-6) to 7 times 10(-5) m, derivatives consisting of the polycylic ring structures fluoranthene, fluorenone, fluorene, anthraquinone, xanthenone, and dibenzofuran with appropriate amine side chains inhibited by over 90% the purified rna-directed dna polymerase of avian myeloblastosis virus acting on poly(deoxyadenylate-deoxythymidylate) [poly(da-dt)]. of these, only the fluoranthene derivatives were strong inhibitors of the viral dna polymerase directed by polyadeny ...	1975	51087
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 ...	1975	51099
group-specific antigenic determinants of the large envelope glycoprotein of avian oncornaviruses.		1975	51537
sequences related to the rna tumor viruses in the rna and dna of human leukemias and lymphomas.	dna-rna hybridization was used to explore whether human neoplasias contain rna molecules having sequence homologies to those of the rna tumor viruses known to cause similar diseases in animals. the pattern of specific rnas found in the human tumors showed a remarkable concordance with the predictions deducible from the animal systems. thus human breast cancer contains rna homologous only to that of the murine mammary tumor virus (mmtv). human leukemias, sarcomas, and lymphomas (including hodgkin ...	1975	51626
region of immunoglobulin light-chain mrna transcribed into complementary dna by rna-dependent dna polymerase of avian myeloblastosis virus.	the mrna coding for a kappa-type immunoglobulin light (l)-chain and its complementary dna (cdna) hybridize with a crt1/2 of 2.6 x 10(-4) moles of ribonucleotide x liter-1 x sec, forming well-matched duplexes (melting temperature tm equals 89 degrees). the molecular weight of the cdna is about 280,000 (840 nucleotides) as determined by alkaline sucrose gradient centrifugation and from the extent of protection of the mrna by the cdna from ribonuclease digestion. the cdna anneals with kappa-type mr ...	1975	52155
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 ...	1975	52156
essential arginyl residues in reverse transcriptase.		1975	52361
transcription of 70s rna by dna polymerases from mammalian rna viruses.	dna polymerases purified by the same procedure from four mammalian rna viruses, simian sarcoma virus type 1, gibbon ape lymphoma virus, mason-pfizer monkey virus, and rauscher murine leukemia virus are capable of transcribing heteropolymeric regions of viral 70s rna without any other primer. in this reconstituted system the enzymes from simian sarcoma virus type 1, mason-pfizer monkey virus, and rauscher murine leukemia virus transcribe viral 70s rna almost as efficiently as the dna polymerase f ...	1975	53295
dna-synthesis on giant nuclear rna by amv dna polymerase.	the reverse transcription of pre-mrna isolated from rat liver or mouse ehrlich ascites carcinoma cells with the aid of hot phenol fractionation technique is described. pre-mrna isolated at 85 degrees c is a more active template than the 65 degree c fraction. the addition of oligo(dt) as a primer strongly stimulated the template activity of the 65 degree c fraction. the size of product corresponds to a sedimentation value of 7 s as measured in alkaline sucrose gradient and is essentially less tha ...	1975	53784
elimination of residual rnase activity from purified preparations of rna-directed dna polymerase.		1975	54167
[study of the reproduction conditions of the avian myeloblastosis virus for separation of the "reverse transcriptase" enzyme].	sensitivity of eight chick lines to the avian myeloblastosis virus as the main source for rna-dependent dna-polymerase recovery was studied in the course of the "revertase" project. the virus (0.1 ml) was inoculated intracardially or intraperitoneally to one-day chicks, and then the virus titer was determined according to the atp-activity. c and d-lines of the enya-cross were shown to be most sensitive (sensitivity 75%) among the lines studied.	1975	56958
comparison between an avian and a murine viral reverse transcriptase-rnase h complex.		1975	60996
[dna synthesis on the heterogeneous nuclear rna template catalysed by dna polymerase of avian myeloblastosis virus].	template activity of nuclear pre-mrna has been investigated in dna-polymerase reaction. active synthesis of dna was demonstrated on pre-mrna as a template in the absence of primer. a part of synthetic activity may be attributed to the traces of dna present in the pre-mrna preparation. addition of oligo(dt)10 to the template stimulated the synthesis of dna product due to transcription of heteropolymeric regions near the poly(a). the rate of dna synthesis was different depending on the fraction of ...	1975	55956
e. coli trnas as inhibitors of viral reverse transcription in vitro.	reverse transcription of 70s amv rna by amv reverse transcriptase has been studied in the presence of e. coli trnas. we have shown that inhibition of dna synthesis occurs and that the trnas bind to the enzyme and not to the 70s rna. the results have implications for the control of reverse transcription in vivo.	1975	79997
hydrodynamic diameters of rna tumor viruses. studies by laser beat frequency light scattering spectroscopy of avian myeloblastosis and rauscher murine leukemia viruses.	the diffusion constants of avian myeloblastosis virus (amv) and murine leukemia virus (mulv) (rauscher) suspensions in buffer and in 30% sucrose were determined by laser beat frequency light scattering spectroscopy at a series of temperatures ranging rom 5 to 25 degrees. by the use of the stokes-einstein equation, the following hydrodynamic diameters are calculated at 20 degrees: mulv, 154 plus or minus 3 nm in sucrose and 145 plus or minus 7 nm in buffer; amv, 144 plus or minus 3 nm in sucrose ...	1975	162827
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 ...	1975	163372
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.	1975	163925
purification and chemical characterization of the major glycoprotein of avian myeloblastosis virus.		1975	164824
affinity chromatography of viral dna polymerases on pyran-sepharose.	pyran covalently linked to cyanogen bromide-activated sepharose has been shown to be an effective affinity matrix for several viral dna polymerases. differential salt elution of viral compared with cellular polymerases, as well as substrate elution, suggests the affinity nature for the matrix. unlike some other affinity systems described, pyran-sepharose is totally resistant to nuclease digestion and is stable at 4 degrees for several months. dna polymerases isolated from several viruses by dete ...	1975	165485
biochemical properties and replication of murine intracisternal a particles during early embryogenesis.		1975	165937
inhibition of rna-dependent dna polymerase reaction by 6-(p-hydroxyphenylazo)-uracil: a result of drug induced dithiothreitol oxidation.	6-(p-hydroxyphenylazo)-uracil (hpura) reduced by dithiothreitol inhibited amv or rlv virion associated exogenous rna-dependent dna polymerase reactions. however, the inhibition was variable from experiment to experiment and was not consistent with the base specificity of hpura seen for inhibition of gram positive dna-dependent dna polymerases. increasing the concentration of dithiothreitol reversed the inhibition. furthermore, at non-toxic concentrations, hpura did not influence the plating effi ...	1975	166420
comparative chemical properties of avian oncornavirus polypeptides.		1975	166483
on the fidelity of dna replication. characterization of polynucleotides with errors in base-pairing synthesized by avian myeloblastosis virus deoxyribonucleic acid polymerase.	polynucleotide templates were copied by avian myeloblastosis virus dna polymerase ("reverse transcriptase") and the frequency and distribution of errors were determined. the error rate with [r(pa)2500-d(pt)12-18] template-initiator under a variety of conditions was approximately 1/600, i.e. one incorrect dcmp incorporated for 600 correct dtmp polymerized. addition of the metal chelator o-phenanthroline to the reaction inhibited the incorporation of correct and incorrect nucleotides proportionate ...	1975	166992
a cell-free mammalian protein-synthesizing system stimulated by rna from avian myeloblastosis virus.	carcinoma cells, oncornavirus-infected cells and fetal bovine tissue provide salt wash ribosomal factors capable of responding to avian myeloblastosis virus (am virus)-rna and stimulating the incorporation of amino acids into proteins as well as catalyzing the binding of n-acetylated (35s) methionyl-trna. the exogenously dependent amino acid incorporation system is stimulated by the high molecular weight species of am virus-rna only, particularly the fraction containing polyadenylate (poly(a)) r ...	1975	167845
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 ...	1975	168849
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 ...	1975	169002
amv rna transcription in cell-free systems and properties of in vitro chromatin-directed rna synthesis.	in this report we have presented evidence that viral sequences in the genome of amv-infected myeloblasts can be transcribed in vitro. the rna products synthesized in either nuclei isolated from these cells or by eukaryotic rna polymerase b from the isolated chromatin contained approximately 1% virus-specific sequences. this result, which is in agreement with the fraction of viral rna in infected cells (garapin et al. 1971), is higher than expected from a random transcription of the genome, and t ...	1975	169005
synthesis of avian rna tumor virus structural proteins.		1975	169008
base sequence complexity of 35s avian myeloblastosis virus rna determined by molecular hybridization kinetics.		1975	169041
polypeptides isolated from ribosome-like structures occluded in avian myeloblastosis virus (amv).	the protein composititon of ribosome-like particles isolated from amv was determined by acrylamide gel electrophoresis and by immunological methods. it was established that the protein spectrum of ribosome-like particles differed significantly form the total protein spectrum of amv. the most characteristic protein components of ribosome-like particles had a molecular weight in the range of 70 000--110 000. apart from these proteins, the viral ribosomal particles contained a small amount of prot ...	1975	169489
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 ...	1975	169823
generation of avian myeloblastosis virus structural proteins by proteolytic cleavage of a precursor polypeptide.		1975	170408
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 ...	1975	170415
human serum lyses rna tumour viruses.		1975	170540
relationship of the first step in protein synthesis to ppgpp: formation of a(5')ppp(5')gpp.	in the presence of purified escherichia coli lysyl-trna synthetase [l-lysine:trnalys ligase (amp-forming) ec 6.1.1.6], l-lysine, and atp, addition of the nucleotide ppgpp results in formation of a unique product-a(5')ppp(5') gpp. the same compound is also formed very rapidly in a cell-free protein-synthesizing system when ppgpp is added. the possible significance of this reaction in the rapid turnover of ppgpp and as a more general mechanism by which an amp residue is activated and introduced on ...	1975	170611
electrophoretic mobilities of rna tumor viruses. studies by doppler-shifted light scattering spectroscopy.	we have used laser beat frequency light scattering spectroscopy to measure, at several ph values, the electrophoretic mobilities of purified avian myeloblastosis (amv), murine leukemia (mulv), murine mammary tumor (mumtv), and feline leukemia (felv) viruses. the mobilities of these viruses are similar at ph greater than or equal to7 (-2.7 to -3.2 x 10(-4) (cm/sec)/(v/cm). the isoelectric points of mulv and amv are apparently less than ph 3, whereas for felv the data could be interpreted to indic ...	1975	170961
partial purification and characterization of dna polymerases from a rous sarcoma virus-transformed rat cell line.	a new dna polymerase was partially purified from cell-free extracts of a continuous rat cell-line (xc). the xc cells had been transformed by the prague strain of rous sarcoma virus but did not produce infectious virus. the molecular weight of the dna polymerase is 70,000, as estimated by glycerol gradient centrifugation and by sephadex gel filtration. this enzyme can be distinguished from the other cellular dna polymerases by its elution pattern on dna-cellulose column chromatography, its molecu ...	1975	170987
synthesis of viral proteins by the avian myeloblastosis viral core component.	avian myeloblastosis viral (amv) core component was isolated and shown to synthesize amv proteins in vitro. this reaction was linearly dependent on viral core concentration, proceeded linearly with time, and was inhibited by puromycin and aurintricarboxylic acid. the proteins synthesized in vitro co-electrophoresed and co-chromatographed with known proteins, and were immunoprecipitated by total and monospecific antibodies to known amv proteins.	1975	170991
analysis of oncornavirus rna subunits by electron microscopy.	subunits of oncornavirus (avian myeloblastosis virus) rna were isolated from purified 60--70s viral rna by heat dissociation. molecules sedimenting at 35 s, assumed to be the major component of the viral genome, were visualized in the electron microscope and their lengths were statistically analyzed. the results indicate a rather heterogeneous population of molecules with five distinct, reproducible size groups, an observation that excludes the assumption of random degradation of the genome. in ...	1975	171673
susceptibility and resistance of chicken macrophages to avian rna tumor viruses.		1975	171840
focus assay and defectiveness of avian myeloblastosis virus.		1975	171844
leukemic transformation with avian myeloblastosis virus: present status.		1975	172289
avian myeloblastosis virus dna polymerase. kinetic studies on the incorporation of noncomplementary nucleotides.	the high error rate characteristic of dna polymerases from rna tumor viruses has permitted measurements on the simultaneous incorporation of complementary and noncomplementary nucleotides during dna synthesis. for example, avian myeloblastosis virus dna polymerase incorporates 1 molecule of dcmp for approximately 500 molecules of dtmp polymerized using polyriboadenylic acid as a template. the parallel incorporation of complementary and noncomplementary nucleotides afer gel filtration of avian my ...	1975	172498
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 ...	1975	172655
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 ...	1975	172660
manganese as a mutagenic agent during in vitro dna synthesis.		1975	173332
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 ...	1975	173876
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 ...	1975	173880
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 ...	1975	179285
[rna-directed dna synthesis in vitro: detection of polydeoxyadenylate in dna, complementary to antimessenger-dna].		1975	55338
absence of polyadenylate segment in globin messenger rna accelerates its degradation in xenopus oocytes.	rabbit globin poly(a)-free and native mrna preparations were microinjected into xenopus oocytes. the amount of globin message remaining after incubation of injected oocytes was determined by molecular hybridization with a radioactive complementary dna probe, synthesized by copying globin mrna with purified rna-dependent dna polymerase (reverse transcriptase) from avian myeloblastosis virus. the results show that 56 hr after injection about 85% of the poly(a)-free mrna molecules are degraded, whi ...	1975	1059092
chromatin as a template for rna synthesis in vitro.	rna transcribed in vitro from myeloblast chromatin by exogenously added rna polymerase b predominantly consists of short chains that remain in hybrid structure with the template; the remainder of the product is free rna of heterogeneous size. addition of polyanions during synthesis caused an increase in the size and amount of free rna with a concomitant decrease in the proportion of small rna. the large molecular weight rna is derived from the short rna chains, which are synthesized de novo duri ...	1975	1090933
a new chemical procedure for 32p-labeling of ribonucleic acids at their 5'-ends after isolation.	a new technique, which utilizes the chemical reaction between [32p]diimidazolidate of orthophosphate and the cetyltrimethylammonium salt of high-molecular-weight rna in nonaqueous dimethyl formamide, has been developed for the 32p-labeling of rnas after isolation. the radioactive label of high specific activity is introduced onto a phosphorylated 5'-end of the rna and renders it suitable for 5'-terminal group analysis. when the labeling reaction was applied to the 70s rna of avian myeloblastosis ...	1975	1090934
comparative ability of rna and dna to prime dna synthesis in vitro: role of sequence, sugar, and structure of template-primer.	the priming efficiency of oligo(rna) vs. oligo(dna) in a homopolymer template-homooligomer primer system was compared using four dna polymerases. the templates included (dt)n, (da)n, (dc)n, and (di)n. primers were the oligomers of the complementary dna or rna with chain lengths of 6 to 23. the dna polymerases used were from micrococcus luteus, avian myeloblastosis virus (amv), and escherichia coli (polymerase i and polymerase iii). the polymerases demonstrated a preference for the dna primers wi ...	1975	1092334
steroid hormone regulation of specific messenger rna and protein synthesis in eucaryotic cells.	evidence is presented that the induction of specific proteins in the chick oviduct by the steroid hormones estrogen and progesterone, involves a primary effect at the level of gene transcription. the intracellular levels of mrna's which code for the synthesis of the egg-white proteins, ovalbumin and avidin, have been quantitated in a heterologous protein synthesizing system. it is demonstrated that these levels are directly dependent upon the inducing steroid, estrogen or progesterone, respectiv ...	1975	1123409
microanalytical and preparative peptide separations with a modified technicon autoanalyzer.		1975	1130666
structural studies on the coat protein of alfalfa mosaic virus. isolation and characterization of the tryptic peptides and the alignment of the cyanogen-bromide fragments.	the reduced and carboxymethylated coat protein of alfalfa mosaic virus (amv 425) was fragmented by means of cyanogen-bromide cleavage. the tryptic peptides from the protein and its four cyanogen-bromide fragments were isolated on a preparative scale by combinations of column and paper separation techniques. the tryptic digest of the carboxymethylated protein contained 24 peptides and two free amino acids. all peptides have been characterized by amino acid analyses and end-group determinations. t ...	1975	1175586
analysis of the pancreatic-ribonuclease-digestion products of alfalfa-mosaic-virus ribonucleic acid. sequence homologies between the different rnas.	alfalfa mosaic virus (amv) genome consists of three pieces of rna (24-s, 20-s and 17-s rna). for infectivity these three rnas and the coat protein are required. in the absence of coat protein, infectivity is obtained by adding the 12-s rna also normally present in the virus. this 12-s rna represents the message for coat protein. thus a redundancy of the gene for coat protein exists between 12-s rna and one of the other rnas. sequence analysis of the oligonucleotides resulting from pancreatic rib ...	1975	1175651
translation of avian myeloblastosis virus rna in a reticulocyte cell-free system.		1976	1247460
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 ...	1976	1250413
restriction of carcinogen-induced error incorporation during in vitro dna synthesis.	the in vitro accuracy of dna replication has been investigated through the measurement of the frequency with which noncomplementary nucleotides were incorporated during polynucleotide replication. the effect of beta-propiolactone treatment of deoxynucleotide templates, ribopolynucleotide templates, and the dna polymerase from avian myeloblastosis virus was determined. treatment of the deoxynucleotide template, poly(da) (see article) oligo(dt) 12-18, by beta-propiolactone resulted in an increased ...	1976	1260750
metal-induced infidelity during dna synthesis.	the effect of several divalent cations on the accuracy of dna replication in vitro has been examined. only be2+ altered the accuracy of dna synthesis using purified dna polymerase (dna nucleotidyltransferase; deoxynucleosidetriphosphate:dna deoxynucleotidyltransferase; ec 2.7.7.7) from avian myeloblastosis virus. the be2+-induced base substitutions occurred with all templates and with all nucleotides tested. analysis of the product by equilibrium density centrifugation and processive hydrolysis ...	1976	1065882
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 ...	1976	932004
mason-pfizer virus rna genome: relationship to the rna of morphologically similar isolates and other oncornaviruses.	the 60-70s rna of mason-pfizer virus (mpv) was iodinated in vitro and used in both direct and competitive molecular hybridization studies. mpv proviral sequences are present at a frequency of approximately one to two copies per haploid genome in the dna of experimentally infected human cells. by nucleic acid competition hybridization, mpv rna was found to be indistinguishable from the rna of a virus (x381) isolated from a rhesus mammary gland and from rna isolated from the cytoplasm of ao cells ...	1976	943573
control of feather keratin synthesis by the availability of keratin mrna.		1976	944576
chromosomal subunits in active genes have an altered conformation.	ten percent digestion of isolated nuclei by pancreatic deoxyribonuclease i preferentially removes globin dna sequences from nuclei obtained from chick red blood cells but not from nuclei obtained from fibroblasts, from brain, or from a population of red blood cell precursors. moreover, the nontranscribed ovalbumin sequences in nuclei isolated from red blood cells and fibroblasts are retained after mild deoxyribonuclease i digestion. this suggests that active genes are preferentially digested by ...	1976	948749
hela cell dna polymerase gamma: further purification and properties of the enzyme.	dna polymerase gamma has been purified over 60 000-fold from hela cells which contain no detectable type c viral particles. this purified enzyme shows a specific activity of 25 000 units/mg of protein which is comparable to the known specific activity of homogeneous preparations of human alpha and beta polymerases. the isolated enzyme shows apparent molecular weights ranging from 160 000 to 330 000 according to the method of analysis. the enzyme exhibits optimal activity for copying poly(a) in t ...	1976	974075
formation of a protein initiation complex on e. coli ribosomes directed by a eukaryotic virus rna.		1976	765152
synthesis of dna complementary to the mrnas for milk proteins by e. coli dna polymerase i.	e.coli dna polymerase i (klenow subfragment) was used for the synthesis of complementary dna with the mrnas for rabbit milk proteins as templates. the cdna formed, contained 200 nucleotides and represented about 20% of the mrna template. the cdna was hybridized specifically to the mrna templates. the klenow subfragment of the e.coli dna polymerase i was as efficient as the avian myeloblastosis virus reverse transcriptase in the synthesis of cdna. the mean size of the cdna fragments obtained with ...	1976	775441
metal activation of dna synthesis.		1976	779784
synthesis of dnas complementary to human ribosomal rnas polyadenylated in vitro.	conditions are described under which poly(a) polymerase from escherichia coli ribosomes will catalyse the addition of amp residues onto the 3'-ends of human 18 s and 28 s ribosomal rnas at an average rate of 40 amp residues per 1000 nucleotides in 20 min. single-stranded complementary dnas (cdnas) can then be transcribed from the polyadenylated rnas with rna-directed dna polymerase from avian myeloblastosis virus. all of the sequences in the rnas are represented in the cdnas; measurements of the ...	1976	782537
sequences related to immunoglobulin kappa chain messenger rna in t cells.	we investigated by molecular hybridization whether t cells contain rna sequences homologous to rna which codes for immunoglobulin kappa-chain (k-chain). a radioactive probe of complementary dna (cdna) was prepared by transcription of purified k-chain mrna from mouse myeloma mopc-41 with reverse transcriptase (rna-dependent-dna nucleotidyltransferase) from avian myeloblastosis virus. the cdna probably corresponded only to the constant region and 3'-terminus of k-chain mrna. kappa-chain cdna was f ...	1976	821055
on the fidelity of dna replication. enzyme activities associated with dna polymerases from rna tumor viruses.	dna polymerase from rna tumor viruses ("reverse transcriptase") has been analyzed for activities which have been associated with other dna polymerases. homogeneous dna polymerase from avian myeoblastosis virus catalyzes pyrophosphate exchange and pyrophosphorolysis. pyrophosphate exchange is dependent on a template and is base-specific. with avian myeloblastosis virus dna polymerase, ribonucleotide templates are more efficient for synthesis while deoxyribonucleotide templates are more effective ...	1976	55414
on the fidelity of dna replication. lack of exodeoxyribonuclease activity and error-correcting function in avian myeloblastosis virus dna polymerase.	homogeneous dna polymerase ("reverse transcriptase") from avian myeoblastosis virus was assayed for exodeoxyribonuclease activity. the substrates were defined template-initiator complexes in which different radioactive nucleotides were present at the 3'-oh termini of the initiator. even when the number of molecules of enzyme was equal to the number of initiator termini there was no significant release of radioactivity with any of the template-initiator combinations tested. under similar conditio ...	1976	55415
use of cross-linking in studying the structure of rna tumour viruses.	treatment of intact avian myeloblastosis virus (amv) with dimethyl suberimidate dihydrochloride (dms), a cross-linking agent specific for amino groups, was found to result in progressive cross-linking among viral proteins, as revealed by polyacrylamide gel electrophoresis (page) in the presence of sodium dodecyl sulphate (sds). free viral proteins were not cross-linked. the cross-linked protein complex with an apparent molecular weight of 50,000 daltons was studied in detail.	1976	9823
a study of the states of aggregation of alfalfa mosaic virus protein.	the states of aggregation of alfalfa mosaic virus (amv) protein have been characterized by sedimentation velocity experiments and electron microscopy. the main association product is a spherical particle with an s value of about 30s. it is highly likely that the assembly of this particle starts with dimers of the 25000 molecular mass unit resulting in an icosahedral particle made of 30 dimers. no intermediate aggregation products have been detected. the clustering pattern of the protein in the c ...	1976	13424