| electrophoretic properties of temperature-sensitive mutant particles of simian virus 40. | forty-five temperature-sensitive strains of simian virus 40 (sv40) particles belonging to four complementation groups were analyzed by agarose gel electrophoresis. five strains (b204, b218, b233, and bc226), which are members of the b and bc complementation groups, yielded virions with aberrant mobilities. genetic mapping by lai and nathans suggested that b and bc mutantions are in a single gene. the mutant virions possessing altered mobilities have greater positive charges than wild-type partic ... | 1975 | 12128 |
| stable mutants of mammalian cells that overproduce the first three enzymes of pyrimidine nucleotide biosynthesis. | upon exposure to 0.1 mm n-phosphonacetyl-l-aspartate (pala), a transition state analog inhibitor of aspartate transcarbamylase, most cells of a simian virus 40 (sv40)-transformed syrian hamster line are killed within a few days, but resistant mutants form spontaneously with frequency 2-5 x 10(-5) in a stochastic process not dependent upon the presence of the inhibitor. the resistant phenotype is stable for many months in the absence of pala. other cell lines also give resistant mutants, but with ... | 1976 | 12870 |
| isolation and properties of a thermostable restriction endonuclease (endo r-bst1503). | a restriction endonuclease was isolated from bacillus stearothermophilus1503-4r (bst1503) and purified to homogeneity. the enzyme required mg2+ ion as a cofactor. bst1503 exhibited maximal activity between ph 7.5 and 8.0, between 60 and 65 degrees c, and with about 0.2 mm mg2+. bst1503 was not inactivated after exposure at 55 or 65 degrees c for up to 10 h. after 2 h of incubation at 70 degrees c, bst1503 was inactivated by 65%. bst1503 was rapidly inactivated at 75 degrees c. a single protein-s ... | 1977 | 14105 |
| characterization of components released by alkali disruption of simian virus 40. | treatment of simian virus 40 (sv40) particles at ph 9.8 in the presence of 1 mm dithiothreitol for 5 min at 37 degrees c disrupted the virions into a 60s dna-protein complex and dna-free 7s protein particles. the dna-protein complex contained approximately equal amounts of dna and protein, and appeared by electron microscopy to be relaxed circular structures with an average of 21 beads joined by short, thin bridges. the major protein components in the complex were host cell histones, but sv40-sp ... | 1977 | 15134 |
| catecholamine hormone receptor differences identified on 3t3 and simian virus-transformed 3t3 cells. | identification and characterization of hormone receptors on the cell surface is an effective tool for studying the plasma membrane. using the direct binding of a radiolabeled antagonist, (-)3halprenolol, to crude membrane preparations, and a physiological response (cellular cyclic amp levels), i demonstrated a catecholamine (beta-adrenergic) hormone receptor site coupled to a catecholamine responsive adenylate cyclase atp pyrophosphate-lyase (cyclizing), ec 4.6.1.1 on 3t3 and simian virus 40 (sv ... | 1977 | 15252 |
| mutagenesis by simian virus 40. ii. changes in substrate affinities in mutant hypoxanthine-guanine phosphoribosyl transferase enzymes at different ph values. | a number of 8-azaguanine-resistant clones selected from chinese hamster cells infected with sv 40, and supposed to originate by virus infection was investigated to demonstrate and analyze genetic alterations occurring in the cells after infection. all resistant clones tested showed reduced but detectable activity levels of the enzyme hypoxanthine-guanine phosphoribosyltransferase. the extent of reduction in the activity was not identical for different substrates. in all the clones tested, sponta ... | 1977 | 21348 |
| the structure of sv 40 chromatin. | simian virus 40 (sv40) nucleoprotein complexes were studied with the electron microscope. depending on the isolation procedure, sv40 chromatin has two different conformations: complexes isolated in the presence of 0.15 m nacl appeared as very compact globular structures, while those isolated in the presence of 0.6 m nacl had the typical 'beads-on-a-string' appearance of the primary nucleofilament. concomitant with this structural change was a variation in the histone pattern and sedimentation be ... | 1978 | 26073 |
| mobility of histones on the chromosome of simian virus 40. | linear simian virus 40 (sv40) chromosomes were prepared by eco r1 nuclease cleavage of the circular sv40 chromosomes released from virions with dithiothreitol at ph 9,8. chromatin-dna hybrids were constructed with segments of 3h-labeled, naked sv40 dna covalently joined via the eco r1-generated cohesive ends to segments of linear sv40 chromosome. upon incubation of chromatin-dna hybrids at 37 degrees c and moderate ionic strength, histones migrated onto the labeled dna while retaining the nucleo ... | 1978 | 31980 |
| decrease of sensitivity to cell-growth inhibitory effect of interferon in human embryo cells after infection with sv40. | no changes in sensitivity of human embryo cells (hec) to the antiviral action of interferon early (i.e. up to 17 days) after infection with simian virus 40 (sv40) could be detected. at the same time the sensitivity of cells to the cell-growth inhibitory effect of interferon decreased considerably. the changes in sensitivity of hec to interferon action occurred during 5 successive passages following the infection with sv40 and remained on a similar level thereafter. during this period, no morphol ... | 1979 | 40423 |
| comparison of the serology, transforming ability, and polypeptide composition of human papovaviruses isolated from urine. | four isolates of human papovaviruses (rf, gs, dw, and mg viruses) obtained from the urine specimens of renal allograft recipients in widely separated locations were compared with bk virus. hemagglutination inhibition tests and plaque neutralization assays showed that all were antigenically related to bk virus. all isolates transformed baby hamster kidney cells, transformation being determined by the ability of the cells to plate in soft agar. purified preparations of each isolate were iodinated ... | 1976 | 56460 |
| identification of the stumptailed macaque virus as a new papovavirus. | a new viral agent, stumptailed macaque virus (stmv), isolated from uninoculated stumptailed macaque kidney cultures was identified. the virions had the size and morphology of papovaviruses of the simian virus 40 (sv40)-polyoma subgroup, but many of them appeared to have an additional outer envelope. the deoxyribonucleic acid of stmv was a superhelical circular molecule, with a mean length 91% of that of sv40. the antigenic relationship of this virus with other members of the group was examined b ... | 1976 | 59705 |
| effect of passage in culture on a clone of balb/c 3t3 cells transformed by simian virus 40. | most simian virus 40 (sv40)-transformed balb/c 3t3 clones employed for biochemical studies have been used without regard to passage level. to determine whether virus-induced properties are stable as a function of passage, we have extensively characterized one transformed clone, fne, which was isolated after sv40 infection balb/c 3t3 cells in factor-free medium. from the initial testing at passage 5 and for at least 50 subsequent subcultures, the cells stably maintained many transformed growth pr ... | 1976 | 59815 |
| immunological properties of murine thymus-dependent lymphocyte surface glycoproteins. | the immunological properties of two murine thymus-dependent (t) lymphocyte surface glycoproteins, t200 and t25, were investigated. t200 is a lymphocyte-specific antigen with a high degree of species specificity. it shares antigenic determinants with molecules present on thymus-independent (b) lymphocytes. t25 has antigenic determinants which cross-react with antigens on mouse brain, rat thymocytes and rat brain. an antiserum against a purified rat brain glycoprotein which carries thy-1.1 reacts ... | 1976 | 61878 |
| primary in vitro sensitization of murine lymphocytes against isogeneic and allogeneic cells transformed by simian virus 40. | primary in vitro sensitization of murine lymphocytes to isogeneic and allogeneic cells transformed by simian virus 40 (sv40) is described. the results of specificity studies utilizing cytotoxic effector lymphocytes obtained by in vitro immunization indicate that sv40 transformation results in the expression of tumor-specific antigens which are recognized by cytotoxic effector cells. moreover, the studies demonstrate that expression of tumor-specific antigens on transformed cells is associated wi ... | 1976 | 62000 |
| membrane-associated antigen from the sv40-induced hamster fibrosarcoma, para-7. i. role in immune complex formation and effector cell blockade. | para-7 membrane-associated antigen was prepared by treatment of the tumor cells with ph 9.4 glycine buffer, or by concentration of spent cell culture medium. when admixed with sensitized effector cells, both preparations could specifically block cellular cytotoxicity for para-7 target cells. pretreatment of target cells with antigen did not result in blocking. incubation of antigen extract with simian virus 40 (sv40) anti-serum caused neutralization of antibody-dependent cellular cytotoxicity (a ... | 1976 | 62726 |
| induction of tumors in syrian hamsters by a human renal papovavirus, rf strain. | injection of rf virus (rfv), a papovavirus isolated from human urine, into newborn syrian hamsters induced subcutaneous sarcomas in 50% of the recipients with 18- to 48-week latent periods. transplantation of 2 x 10(6) primary rfv-induced tumor cells into weaning hamsters caused tumors in 100% of the recipients within 1-2 weeks. continuous tissue culture cell lines were established from two primary tumors; one of these was transplantable. an in vitro-transformed continuous cell line (rf-194) obt ... | 1976 | 63561 |
| effect of ethidium bromide on transplanted virus-induced tumor cells. | ethidium bromide (2,3-diamino-5-ethyl-6-phenylphenanthridinium bromide) significantly inhibited the rna-dependent dna polymerase of types a and c particles isolated from transplanted adenovirus 12-induced tumors of cba mice. it was also cytotoxic for an established in vitro line of adenovirus 12-induced tumor cells of cba mice and caused cell death, inhibition of [3h]thymidine uptake, and a significant reduction of cells in metaphase. ethidium bromide significantly inhibited the in vivo growth o ... | 1976 | 63562 |
| potentiation of cytotoxic t-cell function by virus. | inoculation of c57bl/6j mice with allogeneic p815 mastocytoma cells in the presence of simian virus 40 (sv40), a dna tumor virus, led to an enhanced cytolytic t-cell response to p815 in vivo. cytotoxic function was also augmented if sv40 was given subsequent to a primary immunization, even when mice were given a suboptimal dose of immunizing cells. although sv40 increased the cell-mediated immune response to allogeneic cells, it did not enhance the antibody response to the soluble antigen dinitr ... | 1976 | 63565 |
| the b/c gene of simian virus 40. | | 1976 | 64014 |
| active amino acid transport in plasma membrane vesicles from simian virus 40-transformed mouse fibroblasts. characteristics of electrochemical na+ gradient-stimulated uptake. | selectively permeable membrane vesicles isolated from simian virus 40-transformed mouse fibroblasts catalyzed na+ gradient-coupled active transport of several neutral amino acids dissociated from intracellular metabolism. na+-stimulated alanine transport activity accompanied plasma membrane material during centrifugation in discontinuous dextran 110 gradients. carrier-mediated transport into the vesicle was demonstrated. when na+ was equilibrated across the membrane, countertransport stimulation ... | 1977 | 66232 |
| simian virus 40 tumor-specific proteins: subcellular distribution and metabolic stability in hela cells infected with nondefective adenovirus type 2-simian virus 40 hybrid viruses. | hela cells infected with adenovirus type 2 (ad2)-simian virus 40 (sv40) hybrid viruses produce several sv40-specific proteins. these include the previously reported 28,000-dalton protein of ad2+nd1, and 42,000- and 56,000-dalton proteins of ad2+nd2, the 56,000-dalton protein of ad2+nd4, and the 42,000-dalton protein of ad2+nd5. in this report, we extend the list of sv40-specific proteins induced by ad2+nd4 to include proteins of apparent molecular weights of 28,000 42,000, 60,000, 64,000, 72,000 ... | 1977 | 66327 |
| identification of simian virus 40 tumor and u antigens. | the synthesis and identity of the tumor and u antigens of simian virus 40 (sv 40) have been examined during productive infection in monkey cells, abortive infection in mouse cells, and in sv40-transformed mouse cells by using sodium dodecyl sulfate/polyacrylamide slab gel electrophoresis to analyze [35s]methionine-labeled radioimmune precipitates. the following observations were made: (i) the tumor and u antigenic sites are on the same 94,000, 89,000, and 84,000 molecular weight species detected ... | 1977 | 66677 |
| antigenic distinctions of glycoproteins in plasma and mitochondrial membranes of lymphoid cells neoplastically transformed by simian virus 40. | highly purified plasma membranes from hamster lymphocytes transformed by simian virus 40 (gd 248) were compared with the membranes of normal cells by crossed immune electrophoresis, crossed-line immune electrophoresis, and bidimensional isoelectric focusing-immune electrophoresis. antiserum raised by inoculation of guinea pigs with gd 248 membranes was used as serologic reagent, either directly or after absorption with membranes from normal cells. bidimensional immune electrophoresis reveals the ... | 1977 | 66678 |
| characterization of immune responses to spontaneous hamster lymphomas. | tumor resistance could be induced against the transplantation of cell lines derived from spontaneous lymphomas that occurred in the third of three lymphoma epizootics in a hamster colony. immunization of normal hamsters with irradiated lymphoma cells promoted resistance to homologous lymphoma challenge and prevented the development of spontaneous lymphomas when immunized hamsters were exposed to the contaminated colony. this immunity could be transferred in an adoptive transfer assay. resistance ... | 1977 | 67210 |
| immunofluorescence study of the adenovirus type 2 single-stranded dna binding protein in infected and transformed cells. | high-titer monospecific antiserum against highly purified adenovirus 2 (ad2) single-stranded dna binding protein (dbp) was used to study, by indirect immunofluorescence (if), the synthesis of dbp in ad2-infected human cells and adenovirus-transformed rat, hamster, and human cell lines. in infected cells the synthesis of dbp was first detected in the cytoplasm at 2 to 4 h postinfection and reached a maximum intensity at 6 h postinfection. at this time dbp began to accumulate in the nucleus, where ... | 1977 | 68127 |
| morphological phenotype of temperature-sensitive mutants of simian virus 40 in productive infection. | | 1977 | 68621 |
| dna polymerase activities in growing cells infected with simian virus 40. | growing cv1 cells were infected with simian virus 40 (sv40), and the levels of dna polymerases-alpha, -beta, and -gamma were analyzed in the cytoplasm, nuclear triton wash, and nucleus. in the cytoplasmic fraction, the amount of alpha-, beta-, or gamma-polymerase remained unaltered after sv40 infection. the activity of dna polymerase-alpha increased five- to sixfold in the nuclear triton wash and threefold in the nuclei and then remained enhanced only inside the nuclei. that of dna polymerases-b ... | 1977 | 69720 |
| lack of expression of type c hamster virus after neoplastic transformation of hamster embryo fibroblasts by benzo(a)pyrene. | syrian hamster embryo fibroblasts transformed in vitro with benzo(a)pyrene were analyzed for the presence of type c viral components, including extra- and intracellular reverse transcriptase activity, intracellular type c hamster virus-related rna, and cellular hamster virus group-specific antigen. no evidence could be obtained for the presence of any of these components, although they were easily detectable in hamster fibroblasts producing either b-34 virus (a hamster virus pseudotype of harvey ... | 1977 | 71196 |
| interspecies-, species- and type-specific t antigenic determinants of human papovaviruses (jc and bk) and of simian virus 40. | immunofluorescence tests, absorption studies and quantitative analysis by a very sensitive 51cr microcomplement fixation (cf) technique were used to define the degree of relatedness between the tumor (t) antigens induced by human papovaviruses, strain jc and bk, with simian virus 40(sv40) and mouse polyoma virus (pyv). antisera against jcv, bkv, sv40 and pyv t were raised in tumor-bearing hamsters. the data obtained indicate that t antigens of jcv, bkv and sv40 possess various subspecificities w ... | 1977 | 72046 |
| identification of a chromosome that controls malignancy in chinese hamster cells. | a chromosome that controls malignancy in chinese hamster cells has been identified by analysis of the giemsa banding pattern of a malignant cell line transformed by simian virus 40 (sv40), non-malignant revertants from this line, segregants from the revertants that were again malignant and a cell line transformed by methylcholanthrene. the malignant cell line transformed by sv40 was near diploid and had gained additional material of chromosome 3. revertants with a suppression of malignancy and m ... | 1977 | 73545 |
| simian virus 40 (sv40)-specific proteins associated with the nuclear matrix isolated from adenovirus type 2-sv40 hybrid virus-infected hela cells carry sv40 u-antigen determinants. | the distribution of simian virus 40 (sv40)-specific proteins in nuclear subfractions of pulse-chase-labeled hela cells infected with nondefective adenovirus type 2 (ad2)-sv40 hybrid viruses was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. the sv40-specific proteins of ad2+nd1, ad2+nd2, and ad2+nd5 specifically associate with the nuclear matrix and are virtually absent from the high-salt nuclear extract. in ad2+nd4-infected hela cells, the sv40-specific proteins with mol ... | 1978 | 77334 |
| an immunochemical investigation of sv40 t antigens. 1. production properties and specificity of rabbit antibody to purified simian virus 40 large-t antigen. | | 1978 | 78572 |
| comparative behavior of simian virus 40 t-antigen and of tumor-specific surface and transplantation antigens during partial purification. | the simian virus 40-specific t-antigen has been extracted from sv al/n mouse embryo tissue culture cells by treatment with triton x-100 detergent. the extracts contained tumor-specific transplantation antigen (tsta) and tumor-specific surface antigen. these extracts were purified by ammonium sulfate precipitation and diethyl-aminoethyl cellulose and phosphocellulose column chromatography and were assayed for the three antigens. we found that t-antigen, tsta, and much of the tumor-specific surfac ... | 1978 | 78758 |
| somatic cell hybrids producing antibodies specific for the tumor antigen of simian virus 40. | we have produced somatic cell hybrids between mouse myeloma cells deficient in hypoxanthine phosphoribosyltransferase imp: pyrophosphate phosphoribosyltransferase; ec 2.4.2.8) and spleen cells derived from mice primed with either syngeneic or allogeneic cells transformed by simian virus 40. such hybrids produced antibodies specific for simian virus 40 tumor (t) antigen. only four of twelve independent hybrid cell cultures produced antibodies against simian virus 40 t antigen that crossreacted wi ... | 1978 | 79181 |
| role of na+ in alpha-aminoisobutyric acid uptake by membrane vesicles from mouse fibroblasts transformed by simian virus 40. | the uptake of alpha-amino[(3)h]isobutyric acid (aib) was studied in membrane vesicles from mouse fibroblasts transformed by simian virus 40 to examine the features of the na(+)-stimulated and na(+)-dependent aib transport process. the simultaneous addition of nacl and aib to these vesicles produced a transient accumulation, or "overshoot," of amino acid 3-4 times the equilibrium value. both the initial rate of uptake and the rate of fall of intravesicular aib after maximal accumulation were sens ... | 1978 | 79182 |
| membrane proteins of cells neoplastically transformed by simian virus 40. | | 1978 | 79190 |
| tumor-specific transplantation antigen: use of the ad2+nd1 hybrid virus to identify the protein responsible for simian virus 40 tumor rejection and its genetic origin. | cells transformed by simian virus 40 (sv40) possess a tumor-specific transplantation antigen (tsta) that has the property of immunizing animals against syngeneic tumor challenge. we find that the early sv40 dna segment present in the human adenovirus 2 (ad2)-sv40 hybrid, ad2+nd1, is sufficient to induce this sv40-specific tsta in balb/c mice. moreover, studies on the intracellular distribution of tsta activity in ad2+nd1-infected cells, as determined by the ability of various subcellular fractio ... | 1978 | 80009 |
| characterization of k virus and its comparison with polyoma virus. | the antigenic relationship between the two murine papovaviruses, k virus and polyoma virus, was examined by serological techniques to determine whether they shared any antigenic components. no cross-reactivity was found associated with the viral (v) antigens by the indirect immunofluorescence, neutralization, or hemagglutination-inhibition tests. the tumor (t) antigens expressed in transformed cells or cells productively infected by either k or polyoma virus did not cross-react by indirect immun ... | 1978 | 81318 |
| recognition sequence of restriction endonuclease kpni from klebsiella pneumoniae. | we have determined the recognition sequence of the restriction endonuclease kpni, previously isolated from klebsiella pneumoniae. the enzyme cleaves the twofold rotationally symmetric sequence (see book for formula) at the positions indicated by the arrows, producing 3' protruding cohesive ends, four nucleotides in length. the specific cleavage site was unambiguously deduced using both 3' and 5' end analyses of kpni generated restriction fragments of simian-virus 40 (sv40) dna (1 site), adenovir ... | 1978 | 82935 |
| immunogenic properties of a soluble tumor rejection antigen (tsta) from a simian virus 40-induced sarcoma. | | 1979 | 83307 |
| simian virus 40 specific proteins on surface of hela cells infected with adenovirus 2--sv40 hybrid virus ad2+nd2. | | 1979 | 84340 |
| isolation of single-stranded dna sequences coding for cellular and viral rna in mouse cells transformed by simian virus 40 [proceedings]. | | 1978 | 84624 |
| rapid sequence determination of late simian virus 40 16s mrna leader by using inhibitors of reverse transcriptase. | a method for the determination of the primary structure of spliced mrna junction and leader sequences is described. by analogy to the dna sequencing procedure of sanger et al. [sanger, f., nicklen, s. & coulson, a. r. (1977) proc. natl. acad. sci usa 74, 5463--5467], we use 2",3'-dideoxynucleoside triphosphates as chain-terminating inhibitors of the reverse transcriptase (rna-dependent dna polymerase) reaction. by using specific dna restriction fragments as primers in combination with this techn ... | 1979 | 85304 |
| effect of azacytidine in sv40-infected bsc-1 cells. | 5-azacytidine (5-azacr) reduced significantly the levels of ribosomal 28s and 18s rnas in the cytoplasm of uninfected and simian virus 40 (sv40)-infected bsc-1 cells. the percent inhibition of ribosomal rnas was correlated to both the dose of azacr and the time of exposure. in sv40-infected cultures treated with 200 microgram/ml azacr, a portion of the total cytoplasmic radioactivity was observed to sediment as 19s and 16s by sucrose gradient analysis. the 19s and 16s peaks represented in part t ... | 1979 | 85613 |
| simian virus 40 t- and u-antigens: immunological characterization and localization in different nuclear subfractions of simian virus 40-transformed cells. | simian virus 40 (sv40)-transformed cells and cells infected by the nondefective adenovirus 2(ad2)-sv40 hybrid viruses ad2+nd1 and ad2+nd2 were analyzed for sv40 t- and u-antigens, respectively, using individual hamster sv40 tumor sera or serum for which u-antibodies were removd by absorption. these studies showed that (i) t- and u-antigens can be defined by separate classes of antigenic determinants and (ii) the u-antigenic determinants in sv40-transformed cells and in hybrid virus-infected cell ... | 1979 | 85723 |
| t antigen banding on chromosomes of simian virus 40 infected muntjac cells. | chromosomes were prepared from mitotic munjac cells 48 to 72 h after infection with sv40 virus. when stained for sv40 t antigen by indirect immunofluorescence, all chromosomes within an infected cell were fluorescent, indicating the presence of t antigen. furthermore, the chromosomes were not uniformly stained but appeared to have regions of high and low fluorescence intensity. a variety of controls showed that the banding patterns are specific and highly reproducible and may indeed reflect the ... | 1979 | 88306 |
| simian virus 40 early mrna's. i. genomic localization of 3' and 5' termini and two major splices in mrna from transformed and lytically infected cells. | we have studied the structure of polyadenylated virus-specific cytoplasmic mrna's in mouse and human cells transformed by simian virus 40 and in monkey cells infected with simian virus 40 in the presence of cytosine arabinoside by means of reverse transcriptase-catalyzed complementary dna synthesis and complementary dna sequencing. abundant mrna species containing splices from residues 4490 to 4557 (0.533 to 0.546 map units [m.u.]) and 4490 to 4837 (0.533 to 0.600 m.u.) were identified in both t ... | 1979 | 90157 |
| characterization of the 5'-terminal structure of simian virus 40 early mrna's. | rpc-5 reverse-phase chromatography has been used to isolate fragments of simian virus 40 dna generated by appropriate digestions with restriction endonucleases. ten specific dna fragments, mapping successively in a counterclock-wise direction from 0.67 to 0.515 on the simian virus 40 genome, were each hybridized to cytoplasmic mrna obtained during the early phase of simian virus 40 infection. primer extension methods with reverse transcriptase were used to characterize the 5' ends of two species ... | 1979 | 90173 |
| cell surface location of simian virus 40-specific proteins on hela cells infected with adenovirus type 2-simian virus 40 hybrid viruses ad2+nd1 and ad2+nd2. | hela cells infected with the nondefective adenovirus type 2-simian virus 40 hybrid viruses ad2+nd1 or ad2+nd2 were analyzed for cell surface location of the sv40-specific hybrid virus proteins by indirect immunofluorescence microscopy. two different batches of sera from sv40 tumor-bearing hamsters, serum from sv40 tumor-bearing mice, or two different antisera prepared against purified sodium dodecyl sulfate-denatured sv40 t-antigen, respectively, were used. all sera were shown to exhibit compara ... | 1979 | 90174 |
| transfer of proteins from gels to diazobenzyloxymethyl-paper and detection with antisera: a method for studying antibody specificity and antigen structure. | we describe a rapid and very sensitive method for detecting proteins as antigens after their separation in polyacrylamide/agarose composite gels, with or without sodium dodecyl sulfate. the polyacrylamide matrix is crosslinked with a reagent that can be cleaved with periodate or alkali to facilitate transfer of the protein bands to diazobenzyloxymethyl-paper, where they are coupled covalently. specific proteins are detected by autoradiography after sequential incubation with unfractionated, unla ... | 1979 | 91164 |
| lysosome stability during lytic infection by simian virus 40. | by 48 h postinfection, 40--80% of sv40-infected cv-1 cells have undergone irreversible injury as indicated by trypan blue staining. nevertheless, at this time the lysosomes of these cells appear as discrete structures after vital staining with either acridine orange or neutral red. lysosomes, vitally stained with neutral red at 24 h postinfection, were still intact in cells stained with trypan blue at 48 h. acid phosphatase activity is localized in discrete cytoplasmic particles at 48 h, as indi ... | 1979 | 91590 |
| purification and molecular characterization of adenovirus type 2 dna-binding protein. | an adenovirus type 2 (ad2) dna-binding protein was purified by sequential dna-cellulose, sephadex g-200, and deae-sephadex chromatography, with a yield of 120 mug of binding protein (95 to 99% homogeneity) starting with 2 x 10(9) infected cells. by omitting the sephadex g-200 step, 400 to 600 mug of 95% pure binding protein was obtained. to obtain high yields of highly purified binding protein, it was necessary to include deoxycholate and nonidet p-40 at selected stages during the preparation. t ... | 1977 | 64628 |
| common structural antigen of papovaviruses of the simian virus 40-polyoma subgroup. | an antigenic determinant common to the major capsid polypeptide (vp1) of simian virus 40 (sv40) and polyoma virus is described. antisera prepared against intact viral particles reacted only with cells infected with the homologous virus by immunofluorescence tests (if). however, antisera prepared against disrupted sv40 particles reacted in if with both polyoma- and sv40-infected permissive cells. the cross-reaction with polyoma was localized to vp1 by the following evidence. (i) the if cross-reac ... | 1977 | 64625 |
| antigenic similarity between simian virus 40-induced surface and fetal antigens in hamster. | the tumor-associated cell-surface antigen (tssa) on simian virus 40 (sv40)-transformed hamster cells was studied serologically by a complement-dependent cytotoxicity test. an antiserum was obtained from guinea pigs inoculated with sv40-transformed hamster cells. the serum was cytotoxic to sv40-transformed hamster cells after absorption with 15-day hamster embryo cells, hamster cells transformed either by polyoma virus or adenovirus 12, various tissues of hamster origin (brainliver, spleen, and k ... | 1977 | 64617 |
| effect of azacytidine on simian virus 40 nucleoprotein complexes. | simian virus 40 nucleoprotein complexes synthesized in the presence of 5-azacytidine showed small differences in sedimentation rate on neutral sucrose and buoyant density in metrizamide and cesium chloride. simian virus 40 deoxyribonucleic acid (dna) i, isolated from the nucleoprotein complexes of drug-treated cultures, was found to band at a higher buoyant density and therefore had a decreased ability to bind ethidium bromide. the data indicated that these molecules were deficient in superhelic ... | 1979 | 93427 |
| fanconi's anemia: the preanemic phase. | anticipation of franconi's anemia prior to the development of overt marrow aplasia may prevent some morbidity and mortality from infectious and hemorrhagic complications. a presumptive diagnosis was made in a firstborn child and radial anomalies, small size, elevated fetal hemoglobin, intermittent excessive chromosome breakage and elevated t-antigen expression in fibroblasts infected with simian virus 40. serial studies may help identify infants and young children at risk to develop this type of ... | 1979 | 94509 |
| characterization of a variant of human adenovirus type 2 which multiples efficiently in simian cells. | in a previous report (klessig, j. virol. 21:1243--1246, 1977), the isolation of a variant (h2hr400) of adenovirus serotype 2 (ad2) that overcomes the block to multiplication of wild-type ad2 in simian cells was described. h2hr400 replicates efficiently on both human and simian cells, resulting in virus yields that are comparable to those found when wild-type ad2 infects permissive, human cells. an extensive comparison of the genome of h2hr400 with that of its parent by restriction endonuclease, ... | 1978 | 104054 |
| some sequence similarities among cloned mouse dna segments that code for lambda and kappa light chains of immunoglobulins. | a comparison between the cloned mouse dna segments that were found to code for the lambda and kappa light chains of immunoglobulins established that there were seven short nucleotide sequences, two of which matched 6 out of 7, two 7 out of 8, two 8 out of 9, and one 9 out of 10 bases; these sequences were located either at homologous amino acid positions or at positions displaced by four amino acids or less. they all occurred in the framework regions (frs), five next to the complementarity-deter ... | 1979 | 116235 |
| purification and characterization of dna-dependent atpase ii from escherichia coli. | a new dna-dependent atpase was isolated and purified from soluble extracts of escherichia coli. this enzyme, called atpase ii, has a molecular weight of 86,000 and exists in a monomeric state. it degrades atp (or datp) to adp (or dadp) and pi in the presence of magnesium and requires a double-stranded polynucleotide as cofactor. a correlation between the efficiency as cofactor and the melting point of the polynucleotide has been found; the lower the melting temperature, the higher the stimulatio ... | 1978 | 151684 |
| the interaction of histones with simian virus 40 supercoiled circular deoxyribonucleic acid in vitro. | the interaction of supercoiled, circular sv40 dna with calf thymus histone fractions has been studied. five- to ten-fold less f1 histone is required to complex a given amount of dna compared to the other histones. when the supercoiled dna is converted to either the relaxed circular form, or full length linear molecules, or gragmented linear or denatured stands, the efficiency of complex formation with f1 histone markedly decreases. we conclude that f1 histone has a special ability to interact wi ... | 1975 | 163237 |
| biochemical properties of simian virus 40-transformed 3t3 cell mitochondria. | mitrochondria isolated from simian virus 40-transformed 3t3 and nontransformed 3t3 cells were compared by various biochemical criteria. transformed and nontransformed cell mitochondria had identical densities in linear sucrose and discontinuous bovine serum albumin gradients. the activities of several mitochondria-specific enzymes including cytochrome oxidase, adenylate kinase, nicotinamide adenine dinucleotide (nadh)-cytochrome c reductase, and nadh oxidase were similar in both cell types. howe ... | 1975 | 163320 |
| b-cell origin of hamster lymphoid tumors induced by simian virus 40. | two lymphoid neoplasms induced by simian virus 40 (sv40) in syrian hamsters were analyzed for lymphocyte characteristics. the hymphocytes from both tumors contained membrane-bound ig that was exclusively of 7sgamma2 class. furthermore, neither lymphoid tumor had a complement receptor. thus both tumors oringinated from a particular b-cell population, which suggests that this b-cell type is associated with an sv40 receptor. | 1975 | 163322 |
| effect of simian virus 40 subcutaneous tumors on circulating lipids and lipoproteins in the syrian hamster. | circulating lipid levels and lipoprotein patterns in the syrian hamster were determined at various times after subcutaneous inoculation with simian virus 40 (sv40) strain f, strain a-2895, or fortner melanoma tumor cells. sv40 f tumors induced a rapid triphasic elevation of serum total lipids through inhibition of prebeta lipoprotein catabolism. alpha lipoprotein levels declined in proportion to tumor mass. liver wet weight and total lipid content increased significantly, but a normal rate of 3h ... | 1975 | 163332 |
| inhibition of the cellular immune response to simian virus 40 tumor cells in tumor-bearing and tumor-immune mice by concanavalin a. | the effects of in vivo-administered concanavalin a (con a) on the kinetics of the primary and secondary cellular immune responses to simian virus 40-transformed tumor cells were investigated in balb/c mice. either a single initial dose of 400 mug con a or daily doses of 50 mug depressed the cell-mediated immune response to tumor cells during the progressive growth of tumors, as determined by a radioisotopic foot-pad assay. the immune depression correlated with an increase in ultimate tumor weigh ... | 1975 | 163333 |
| products of complementation between temperature-sensitive mutants of simian virus 40. | temperature-sensitive mutants of the d complementation group of simian virus 40 exhibit delayed complementation. analysis of the thermal stability, kinetic profiles in temperature shift experiments, and progeny of complementation have led to the hypothesis that delayed complementation is not true complementation, but the result of a very low level of leakiness, followed by phenotypic mixing of the progeny d mutants. this hypothesis is consistent with the proposal that d mutants are defective in ... | 1975 | 163338 |
| dna infectivity and the induction of host dna synthesis with temperature-sensitive mutants of simian virus 40. | host dna synthesis is induced when cv-1 (monkey kidney) cell cultures are infected at 40 c with wild-type virions or with temperature-sensitive simian virus 40 mutants of the "early" complementation group a. host dna synthesis is not induced when cultures are infected with mutants of the late complementation group d. the simplest explanation for these observations, that induction depends not upon the expression of some early gene function but rather on the presence of an active d protein in the ... | 1975 | 163339 |
| electron microscope localization of a protein bound near the origin of simian virus 40 dna replication. | a salt-stable complex of protein and viral dna obtained from simian virus 40 (sv40)-infected monkey cells or mature sv40 virions has a novel structure. when viewed by high resolution electron microscopy, the circular sv40 dna molecule has bound to it one to three globular protein "knobs". using ecori and hpaii restriction endonucleases, each of which can cleave sv40 dna once at a known location (10, 11, 12, 14), the bound protein can be localized at 0.7 plus or minis 0.05 on the sv40 dna physica ... | 1975 | 163341 |
| characterization of human papovavirus bk dna. | the dna of the bk virus (bkv) human papovavirus was found to be heterogeneous, consisting of at least four discrete species of dna. only the largest of these four species, bkv dna (i), which has a molecular weight calculated to be 96% that of simian virus 40 (sv40) dna, was infectious. homogeneous preparations of bkv dna were obtained, however, from virions purified after low multiplicity infections of human embryonic kidney cells. bkv dna (i) was shown to contain a single r-eco ri and four r-hi ... | 1975 | 163342 |
| stimulation of adenovirus replication in simian cells in the absence of a helper virus by pretreatment of the cells with iododeoxyuridine. | pretreatment of african green monkey kidney cells with 50 mu g of 5'-iododeoxyruidine (iudr) per ml can modify their susceptibility to the replication of human adenovirus type 7 in the absence of simian virus 40 (sv40) although this enhancement of adenovirus replication is not as efficient as that of the helper sv40 virus. since the number of infectious centers remains unchanged after iudr pretreatment whereas the burst size of virus from each infected cell increases, the iudr appears to allow e ... | 1975 | 163353 |
| structural proteins of simian virus 40. i. histone characteristics of low-molecular-weight polypeptides. | the dna-associated polypeptides of simian virus 40 (sv40), vp4 (mol wt 14,000), vp5 (mol wt 12,000), and vp6 (mol wt 11,000), have several properties characteristic of cell histones. after extraction from purified sv40 with dilute acids, these three polypeptides co-electrophoresed on low ph polyacrylamide gels with monkey-kidney cell histones f3, f2b, and f2a1. no virus polypeptide co-electrophoresed with histone f1. polypeptides vp4, 5, and 6 lacked tryptophan, and only vp4 contained cysteine, ... | 1975 | 163362 |
| posttranscriptional selection of simian virus 40-specific rna. | analysis of the viral-specific rna in simian virus 40(sv40)-infected monkey kidney cells indicated the extensive transcription of both dna strands. these symmetrically transcribed sequences were localized in the nucleus of infected cells, whereas only the "true" early and late sv40 transcripts were found in the cytoplasm. these results suggest that selective posttranscriptional degradation and/or transport occurs after transcription of the viral dna. on the basis of hybridization experiments wit ... | 1975 | 163366 |
| proteins in intracellular simian virus 40 nucleoportein complexes: comparison with simian virus 40 core proteins. | intracellular nucleoprotein complexes containing sv40 supercoiled dna were purified from cell lysates by chromatography on hydroxyapatite columns followed by velocity sedimentation through sucrose gradients. the major protein components from purified complexes were identified as histone-like proteins. when analyzed by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels, complex proteins comigrated with viral core polypeptides vp4, vp5, vp6, and vp7. (3h) tryptophan was not detected in ... | 1975 | 163367 |
| stimulation of non-histone chromosomal protein synthesis in simian virus 40-infected simian cells. | the pattern of synthesis of non-histone chromosomal proteins in simian virus (sv) 40-infected african green monkey kidney cells was analyzed by polyacryl-amide gel electrophoresis to see whether the changes in chromosomal protein metabolism are involved in the viral-induced synthesis of cellular dna and mrna. during the prereplicative phase of infection, the rate of histone synthesis was decreased until 15 h postinfection, whereas that of non-histone protein synthesis was increased after 5 h pos ... | 1975 | 163368 |
| simian virus 40 functions required for the establishment and maintenance of malignant transformation. | members of the five classes of temperature-sensitive simian virus 40 mutants were tested for their ability to transform chinese hamster lung cells. two criteria for transformation were used: the ability to form clones in medium with low serum concentrations and the ability to overgrow a monolayer. only a mutants failed to transform at the restrictive temperature when subconfluent chinese hamster lung monolayers were used. however, both a and d mutants failed to transform at the restrictive tempe ... | 1975 | 163374 |
| function of simian virus 40 gene a in transforming infection. | in productive infection by simian virus 40, the a gene is known to regulate the initiation of viral dna replication and to control the synthesis of late viral rna. the function of the a gene in transforming infection was investigated by the infection of a variety of cell species with six independently isolated temperature-sensitive mutants belonging to the a complementation group. the a mutants failed to initiate the stable transformation of cells during continuous infection at the restrictive t ... | 1975 | 163375 |
| role of simian virus 40 gene a function in maintenance of transformation. | mouse, hamster, and human cells were transformed at the permissive temperature by mutants from simian virus 40 (sv40) complementation group a in order to ascertain the role of the gene a function in transformation. the following parameters of transformation were monitored with the transformed cells under permissive and nonpermissive conditions: morphology; saturation density; colony formation on plastic, on cell monolayers, and in soft agar; uptake of hexose; and the expression of sv40 tumor (t) ... | 1975 | 163376 |
| simian virus 40 gene a function and maintenance of transformation. | transformants have been isolated after infection of rat embryo cells at 33 c with either wild-type simian virus 40 or with the temperature-sensitive gene a mutants, tsa7 and tsa28. examination of properties usually associated with transformation such as growth in 1% serum, growth rate, saturation density, and morphology show that these properties are temperature dependent in the tsa transformants characterized, but are not temperature dependent in the wild-type transformants that have been exami ... | 1975 | 163377 |
| structural proteins of a human papovavirus (bk virus): a comparison with the structural proteins of simian virus 40. | | 1975 | 163541 |
| virion polypeptide composition of the human papovavirus bk: comparison with simian virus 40 and polyoma virus. | the polypeptide composition of labeled bk virus was compared with that of simian virus 40 (sv40) and polyoma virus by co-electrophoresis of disrupted virions in polyacrylamide gels containing approximately 73% of the capsid protein and had a molecular weight of 39,000. it was smaller than vp1 of sv40 and polyoma virus. the other polypeptides of bk virus were similar in molecular weight to those of sv40. a comparison of the proteins of bk virus and sv40 iodinated with chloramine t before and aft ... | 1975 | 163921 |
| chromosome analysis of a simian virus 40-transformed mouse cell line and two variant sublines that are resistant to cytochalasin b1. | the chromosomes of an sv40-transformed mouse cell line, svt2, were analyzed by the acetic-saline-giemsa banding technique. by contrast to most established mouse lines, svt2 cells possess a remarkably homogeneous chromosome complement and contain two copies of most chromosomes. however, trisomy for chromosome 3 is a distinct feature of this cell line. chromosomes 1, 3, 14, and 19 have given rise to biarmed markers. two cytochalasin b-resistant sublines derived from svt2 are also essentially diplo ... | 1975 | 164282 |
| neoplastic differentiation: interaction of simian virus 40 and polyoma virus with murine teratocarcinoma cells in vitro. | the host-virus interactions of simian virus 40 (sv40) and polyoma virus (py) with cell lines established from a teratocarcinoma were studied. the cells utilized in this study were the multipotential stem cell of the teratocarcinoma, embryonal carcinoma, and differentiated cells derived from embryonal carcinoma. several lines of differentiated cells were established in vitro which included parietal yolk sac, epithelial, and spindle cell types. embryonal carcinoma cells are not susceptible to infe ... | 1975 | 164473 |
| distribution of membrane particles and gap junctions in normal and transformed 3t3 cells studied in situ, in suspension, and treated with concanavalin a. | freeze-fracture techniques were used to study the ultrastructural distribution of plasma membrane particles in cultures of normal balb/c and swiss 3t3 and simian virus 40- or murine sarcoma virus-transformed fibroblasts. no apparent differences were observed. cultures fixed in situ show a seemingly random distribution of membrane particles both in normal or in transformed cells. treatment of cell cultures in situ with concanavalin a does not result in an altered pattern of particle distribution. ... | 1975 | 164659 |
| simian virus 40-related antigens in three human meningiomas with defined chromosome loss. | two out of seven meningiomas tested in early cell cultures by indirect immunofluorescence staining showed simian virus 40 (sv40)-related tumor (t) antigen. in one tumor 90% of the cells were positive. an additional sv40-related antigen (u) was found in 10% of cells of a third tumor. these findings indicate that the meningioma cells showing a positive reaction are transformed by a papova virus that has at least partly the same antigenic properties as sv40 virus. sv40-related viral capsid (v) anti ... | 1975 | 164660 |
| initiation and maintenance of cell transformation by simian virus 40: a viral genetic property. | the transforming ability in 10% serum medium of the temperature-sensitive mutants of simian virus 40 in the complementation group iii (ts640 type mutants) was greatly reduced when the infected rat 3y1 cells were incubated at the restrictive temperature of 40 degrees or incubated first at 40 degrees for 3 days and then shifted to the permissive temperature of 33 degrees. transformation did occur efficiently after incubation at 33 degrees or after an initial incubation at 33 degrees for 5 days fol ... | 1975 | 164665 |
| synthesis of superhelical simian virus 40 deoxyribonucleic acid in cell lysates*. | in vivo-labeled sv40 replicating dna molecules can be converted into covalently closed superhelical sv40 dna (sv40(i) using a lysate of sv40-infected monkey cells containing intact nuclei. replication in vitro occurred at one-third the in vivo rate for 30 min at 30 degrees. after 1 hour of incubation, about 54% of the replicating molecules had been converted to sv40(i), 5% to nicked, circular molecules (sv40(ii), 5% to covalently closed dimers; the remainder failed to complete replication altho ... | 1975 | 165197 |
| sarcoma in a hamster inoculated with bk virus, a human papovavirus. | an undifferentiated sarcoma occurred in 1 of 52 hamsters inoculated when newborn with bk virus (bkv), a simian virus 40 (sv40)-related human papovavirus. it was transplantable and grew in tissue culture. sera of tumor-bearing hamsters were without antibodies reactive to bkv virion antigens in hemagglutination-inhibition and neutralizationtexts, but contained antibodies reactive in immunofluorescence (if) tests to sv40 t antigen in sv40-transformed cells and to antigens in cells acutely infected ... | 1975 | 165302 |
| inhibition of embryonic cell aggregation by neoplastic cells. | the effects of normal and malignant cells on the aggregation of embryonic cells in gyratory shaker cultures were compared. the addition of 1 times 10-5 simian virus 40 (sv40)-transformed balb/3t3 (sv40-3t3) cells to 6 times 10-6 embryonic neural retina cells caused a highly significant greater reduct on (22.7 percent) in aggregate diameter than the addition of untransformed balb/3t3 (3t3) cells. the ratio of the number of single cells to the number of aggregates was significantly higher for cult ... | 1975 | 165304 |
| immunization with a lipid-conjugated membrane antigen to suppress growth of a fibrosarcoma induced by simian virus 40. | the covalent conjugation of fatty acid to a tumor cell membrane preparation transformed it from an antigen that enhanced tumor growth to one that suppressed it. a crude cell membrane preparation was made by sequential hypertonic and hypotonic salt extraction of tumor cells from a fibrosarcoma induced in hamsters by simian virus 40. the membranes were chemically conjugated with dodecanoic anhydride in 0.5 m carbonate buffer (ph 9.0). injection of unmodified membranes 10 days before transplantatio ... | 1975 | 165307 |
| cyclic amp and cyclic gmp concentrations in serum- and density-restricted fibroblast cultures. | mouse fibroblasts transformed by simian virus 40 (sv3t3 cells) are characterized by cyclic amp and cyclic gmp levels, respectively, about half and twice those found in growing untransformed 3t3 cells. density-dependent inhibition of growth is correlated with reduced cyclic gmp concentrations in 3t3 and four different density-restricted revertant lines derived from sv3t3. the levels of cyclic amp are not increased at confluence. upon serum restriction, serum-dependent cell lines show a greater in ... | 1975 | 165482 |
| biochemical method for mapping mutational alterations in dna with s1 nuclease: the location of deletions and temperature-sensitive mutations in simian virus 40. | s1 nuclease (ec 3.1.4.x), a single-strand-specific nuclease, can be used to accurately map the location of mutational alterations in simian virus 40 (sv40) dna. deletions of between 32 and 190 base pairs, which are at or below the limit of detectability by conventional electron microscopic analysis of heteroduplex dnas, have been located in this way. to map a deletion, a mixture of unit length, linear dna, prepared from the sv40 deletion mutant and its wild-type parent, are denatured and reannea ... | 1975 | 165498 |
| patterns of organization of actin and myosin in normal and transformed cultured cells. | the patterns of distribution of intracellular actin and myosin were examined by specific immunofluorescence in a series of normal, simian-virus-40-transformed, and revertant cell lines of rat and mouse origin. a consistent correlation was found between sensitivity to anchorage-dependent growth control and the presence of large, thick sheaths of actin-containing material. the presence of these sheaths was temperature-dependent in a rat line transformed by a temperature-sensitive mutant in the com ... | 1975 | 165499 |
| biochemical procedure for production of small deletions in simian virus 40 dna. | a simple biochemical procedure for producing small deletions (15 to 50 base pairs) at virtually any location in simian virus 40 dna has been developed. the steps involved are: cleavage of the closed-circular dna to produce a linear structure followed by 5'-exonuclease digestion to expose a short single-stranded segment at each 3' end of the molecule. mutants containing deletions at the site of the cleavage are obtained by infecting permissive monkey kidney cells with the exonuclease-treated dna ... | 1975 | 165505 |
| somatic cell hybrids between mouse peritoneal macrophages and simian-virus-40-transformed human cells: ii. presence of human chromosome 7 carrying simin virus 40 genome in cells of tumors induced by hybrid cells. | cells derived from tumors induced in "nude" mice after injection of cells that were hybrids between mouse peritoneal macrophages and simian virus 40 (sv40)-transformed human cells were found to retain the human chromosome 7 carrying the sv40 genome, and indicate that the presence of human chromosome 7 carrying the sv40 genome is responsible for the expression of the tumorigenic phenotype in the hybrid cells. | 1975 | 165506 |
| t antigen binds to simian virus 40 dna at the origin of replication. | a technique employing ferritin-conjugated antibody has been developed to visualize specific protein-dna complexes in the electron microscope and has been used to demonstrate the preferential binding of simian virus 40 (sv40) t antigen at or near the origin of replication of sv40 dna, 0.67 fractional length clockwise from the ecori restriction endonuclease cleavage site. urified covalently closed supercoiled circles of sv40dna were treated with partially purified t antigen and the complex was sta ... | 1975 | 165517 |
| biologic and antigenic similarity of virus-induced migration inhibition factor to conventional, lymphocyte-derived migration inhibition factor. | macrophage migration inhibition factor (mif) is one of a class of lymphocyte-derived mediator substances (lymphokines) which plays a role in the mechanism of cellular immunity. a variety of other soluble factors produced by non-lymphoid cells have been shown to have effects on macrophage mobility similar to that of mif. in the present study we demonstrate that one such factor, (mifv) derived from simian virus 40-infected kidney cells in culture, has several other properties in common with lympho ... | 1975 | 165520 |
| enhancement of the replication of human adenovirus in simian cells by a series of temperature-sensitive mutants of simian virus 40. | | 1975 | 165626 |
| regulation mechanism of simian virus 40 late gene expression in primary kidney cells and simian virus 40 transformed 3t3 cells. | | 1975 | 165627 |
| amino acid and sugar transport incells permissively infected with simian virus 40. | transport of alpha-aminoisobutyric acid and 2-deoxy-d-glucose in african green monkey kidney cells was measured 8 to 100 hr following permissive simian virus 40 infection. no differences in transport were detected during the time-period studies, and no significant differences were seen between the apparent michaelis-menten constants of normal and virally infected cells. the absence of transport enhancement in permissive simian virus 40 infection suggests that the augmented transport of viral-tra ... | 1975 | 165886 |
| regulation of tumor antigen synthesis by simain virus 40 gene a. | simian virus 40 gene a has previously been shown to promote the replication of viral dna and the transcription of late viral rna in productive infection and to maintain the growth characteristics of some transformed cells. the present study examines the effect of the a function on proteins synthesized during productive and transforming infections. under restrictive conditions, temperature-sensitive a mutants induce the overproduction of a 100,000-dalton protein both in productively infected monk ... | 1975 | 166203 |
| in vitro transformation of rat and mouse cells by dna from simian virus 40. | primary rat kidney cells and mouse 3t3 cells can be transformed by dna of simian virus 40 when use is made of the calcium technique (graham and van der eb, 1973). the transformation assay in primary rat cells is reproducible, but the dose response is not linear. | 1975 | 166204 |