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modified 5'-nucleotides resistant to 5'-nucleotidase: isolation of 3-(3-amino-3-carboxypropyl) uridine 5'-phosphate and n2, n2-dimethylguanosine 5'-phosphate from snake venom hydrolysates of transfer rna.a procedure for the quantitative measurement of the o2'-methylnucleoside constitutents of rna has recently been developed in this laboratory (gray, m.w. can. j. biochem. 53, 735-746 (1975)). this assay method is based on the resistance of o2'-methylnucleoside 5'-phosphates (pnm) (generated by phosphodiesterase hydrolysis of rna) to subsequent dephosphorylation by venom 5'-nucleotidase (ec 3.1.3.5). in the present investigation, two base-modified 5'-nucleotides, each displaying an unusual resista ...19766133
the production of chinese hamster interferon. 197611678
expression of differentiated functions in hepatoma cell hybrids: ix extinction and reexpression of liver-specific enzymes in rat hepatoma-chinese hamster fibroblast hybrids.most of the hybrid clones derived from a cross of chinese hamster fibroblasts (don) with rat hepatoma cells (faza 967) showed preferential loss of rat chromosomes. two of the hybrid clones retained the rat chromosomes, and both showed extinction of 4 liver-specific enzymes: aldolase b, liver alcohol dehydrogenase, and the inducible enzymes tyrosine aminotransferase and alanine aminotransferase. subcloning of 1 of these hybrids, which contained 2 sets of hepatoma chromosomes and 1 set of hamster ...197517164
folate-dependent enzymes in cultured chinese hamster cells: folypolyglutamate synthetase and its absence in mutants auxotrophic for glycine + adenosine + thymidine. 197718110
regional assignment of seven genes on chromosome 1 of man by use of man-chinese hamster somatic cell hybrids. i. results obtained after hybridization of human cells carrying reciprocal translocations involving chromosome 1.regional localization studies of genes coding for human pgd, pph1, pgm1, ugpp, guk1, pep-c, and fh, which have been assigned to chromosome 1, were performed with man-chinese hamster somatic cell hybrids, informative hybrids that retained fragments of the human chromosome 1 were produced by fusion of hamster cells with human cells carrying reciprocal translocations involving chromosome 1. analysis of the hybrids that retained one of the translocation chromosomes or de novo rearrangements involvin ...197718324
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 ...197721348
gamma-glutamyltransferase in human diploid fibroblasts and other mammalian cells.gamma-glutamyltransferase was determined in wi-38 human diploid fibroblasts and compared to enzyme levels determined in several other mammalian cell lines including: fibroblast-like cells from human skin, tibia and foreskin; epithelial-like cells from human, bovine and monkey kidney; and transformed cells (chinese hamster ovary, hela s3 and sv-40 transformed wi-38). transformed cells had the lowest activity found followed in increasing order by fibroblasts, human and bovine epithelial cells and ...197827446
interspecies interactions of arboviruses. iii. competition for virus envelope antigens in mixed getah and sindbis virus populations.interactions of getah and sindbis virus populations in mixed infections of 5 tissue systems were competitive or neutral. the type of interaction is regulated by the host cell and virus population density. on reproduction in mouse brains and spev cell cultures the mixed population exhibited antigenic markers of getah virus; in syrian hamster kidney and chick embryo cell cultures those of sindbis virus; and in chinese hamster kidney cell cultures the antigenic markers of both viruses. mixed popula ...197829465
growth of infective forms of trypanosoma (t.) brucei on buffalo lung and chinese hamster lung tissue culture cells.infective cultures of trypanosoma (t.) brucei (strain 427) have been initiated and maintained on chinese hamster lung tissue culture cells and buffalo lung tissue culture cells. by changing daily one-third of the rpmi-1640 plus 20% fetal bovine serum medium, the cell numbers can be maintained at 2--4 x 10(6) cells/ml. the cultured trypanosomes on these two tissue culture cell types were infective to mice and morphologically similar to bloodstream slender trypomastigotes in having a subterminal k ...197831773
purification and chemical characterization of the heat-labile enterotoxin produced by enterotoxigenic escherichia coli.heat-labile enterotoxin (lt) produced by a human strain of enterotoxigenic escherichia coli (286c(2)) was purified to homogeneity from ph extracts of fermentor-grown cells by ultrafiltration, (nh(4))(2)so(4) fractionation, hydrophobic chromatography on norleucine-sepharose 4b, hydroxylapatite chromatography, and bio-gel p-150 filtration. purified lt preparations exhibited biological activity comparable to that of cholera toxin in four bioassays specific for the two enterotoxins (y-1 adrenal tumo ...197939893
mechanism of action of yersinia enterocolitica enterotoxin.enterotoxin derived from three clinical isolates of yersinia enterocolitica was compared with the heat-stable enterotoxin of escherichia coli. both toxins were biologically active in infant mice examined at 2 h and in ligated rabbit ileal loops at 6 h. neither substance, however, produced changes in ligated ileal loops at 18 h or in chinese hamster ovary or y1 adrenal tissue cultures. in addition, both y. enterocolitica enterotoxin concentrated approximately 20 times by ammonium sulfate precipit ...197939894
visualization of nucleolar organizer regions im mammalian chromosomes using silver staining.a simple ammoniacal silver staining procedure, designated ag-as, differentially stains the chromosomal locations of ribosomal dna in certain mammalian species. this was critically demonstrated by ag-as staining of the nucleolus organizer regions in karyotypes of the same species and cell lines used for locating the ribosomal cistrons by dna/rna in situ hybridization. with ag-as, silver stained nors (ag-nors) are visualized as black spherical bodies on yellow-brown chromosome arms. ag-nors were v ...197553131
enterotoxigenic escherichia coli and idiopathic diarrhoea in bangladesh.faecal escherichia coli from bangalee patients with idiopathic diarrhoea were tested in the chinese hamster ovary cell (c.h.o.) assay to detect production of thermolabile enterotoxin (l.t.). c.h.o-positive e. coli produce both l.t. and a thermostable toxin (s.t.). c.h.o.-positive strains were found in 19.2% of all cases and in 70% of the most severely ill patients with non-vibrio cholera. e. coli which produce s.t. alone were identified in a third of the c.h.o.-negative cases. enterotoxigenic e. ...197553601
enterotoxin testing of escherichia coli causing epidemic infantile enteritis in the u.k.three test systems were used to study enterotoxin production by epidemic strains of escherichia coli from cases of infantile enteritis in well-documented outbreaks in the u.k. the tests used were the y1-mouse-adrenal-cell test and the chinese-hamster-ovary-cell (c.h.o.) test for the detection of heat-labile enterotoxin and the infant-mouse test for the detection of heat-stable enterotoxin. all 6 outbreaks had been studied using full serotyping techniques and the results had been published. in ea ...197655904
streptozotocin and renal amyloidosis in the syrian hamster.in the syrian hamster, administration of the drug streptozotocin was associated with an increased incidence and severity of renal amyloidosis. some of the more severely affected animals showed a frankly nephrotic picture. although some of the diseased animals showed decreased levels of serum albumin, no other definite changes in serum proteins were noted, nor was there any evidence of glomerular immunoglobulin or immune complex deposition. none of the lesions previously found after administratio ...197659551
cell surface antigens. iv. immunological coorespondence between glycophorin and the a1 human cell surface antigen.a stable human-chinese hamster ovary cell hybrid has been produced which, in addition to the complement of chinese hamster ovary (cho-k1) chromosomes, contains only one human chromosome, no. 11. the human cell-surface antigens whose expression is controlled by human chromosome 11, and are expressed by this hybrid, have been defined as the al immunogenetic complex. although one component of this immunogenetic complex (a1) is also expressed by human red blood cells, a second component (a2) is not. ...197661843
ten model mutagens evaluated by the micronucleus test.the following ten mutagenic compounds were subjected to the micronucleus bone marrow test (mnt) in the mouse: cyclophosphamide (ctx), thiotepa (tt), vincristin (vcr), colcemid (colc), adriamycin (am), bleomycin (bm), cytosin arabinoside (ara c), 6-mercaptopurine (6-mp), methotrexate (mtx) and 5-fluorouracil (5-fu). dose-effect curves were established for all compounds. with the exception of ctx, colc and am, the drugs also were subjected to chromosome analyses on chinese hamster fibroblasts in v ...197664925
neutralization of salmonella toxin-induced elongation of chinese hamster ovary cells by cholera antitoxin.a partially purified preparation of the delayed skin permeability factor from salmonella typhimurium caused chinese hamster ovary cells to elongate. the elongation effect and the skin test activity were blocked by monospecific rabbit antisera against cholera toxin and against the b fragment of cholera toxin,197767084
pretreatment of hamster cells with phenethyl alcohol alters cell surface glycoproteins and inhibits vesicular stomatitis virus growth.chinese hamster ovary cells cultured in the presence of phenethyl alcohol exhibit obvious changes in cell surface galactose and galactosamine glycoproteins as determined by the galactose-oxidase[3h]borohydride technique and sds gel electrophoresis. cells pretreated with phenethyl alcohol (drug was removed before infection) were not as effective as hosts for vesicular stomatitis virus as untreated cultures. a minimum pretreatment time with 0.1% phenethyl alcohol of about 8 h was required before a ...197768807
further studies on hybrid cell-surface antigens associated with human chromosome 11.a new human immunogenetic cell-surface activity associated with human chromosome 11 in the al human-chinese hamster ovary cell hybrid is described. like a1, but not a2, it is present on the human erythrocyte. by mutagenesis and selection, specific, stable, variants of the al hybrid have been prepared exhibiting various combinations of a1, a2, a3, and lactic dehydrogenase a activities. the antigens of the al system can be demonstrated by the horseradish peroxidase system which offers a promising ...197774861
purine mutants of mammalian cell lines: iii. control of purine biosynthesis in adenine phosphoribosyl transferase mutants of cho cells.spontaneous and mutagen-induced 2,6-diaminopurine-resistant mutants of chinese hamster ovary (cho-k1) cells were isolated. such mutants fell into two classes: spontaneous and ethylmethane-sulfonate-induced mutants had approximately 5% wild-type adenine phosphoribosyl transferase (aprt) activity, whereas icr-170g-induced mutants had barely detectable aprt activity. since it has been reported that human hypoxanthine-guanine phosphoribosyl transferase (hgprt) (lesch-nyhan syndrome) and aprt mutants ...197775575
[modified method of differential staining of sister chromatids].a modified method of obtaining differential staining of sister chromatids is described. it is simple, rapid, and effective, and at the same time inexpensive and accessible, since it allows one to use available reagents. when 5-bromdeoxyuridine was administered 24 hours before fixation into the chinese hamster cell culture the percentage of metaphases with a differential chromatid staining constituted 95--98, and when this substance was administered 28 hours before fixation into the human lymphoc ...197875748
molecular mechanisms involved in the production of chromosomal aberrations. i. utilization of neurospora endonuclease for the study of aberration production in g2 stage of the cell cycle.chinese hamster ovary cells (cho) were x-irradiated in g2 stage of the cell cycle and immediately treated, in the presence of inactivated sendai virus, with neurospora endonuclease (e.c. 3.1.4.), an enzyme which is specific for cleaving single-stranded dna. with this treatment, the frequencies of all types of chromosome aberrations increased when compared to x-irradiated controls. these results are interpreted as due to the conversion of some of the x-ray induced single-stranded dna breaks into ...197883535
fibroblast interferon in man is coded by two loci on separate chromosomes.we have examined viral and poly(rl):poly(rc) induction of interferon synthesis in several human, mouse and chinese hamster cell lines, and in hybrids derived from the fusion of such cells. we observed species and cell-type differences in inducer effectiveness and in the kinetics of interferon production. in some cases, parental characteristics are preserved in somatic cell hybrids, and in other cases, the expression of the donor phenotype is modulated by the epigenetic state of the recipient cel ...197984714
pattern of condensation of mouse and chinese hamster chromosomes in g2 and mitosis of 33258-hoechst-treated cells. 197989960
the relation between chemically induced sister-chromatid exchanges and chromatid breakage.studies of classical chromosome aberrations and sister-chromatid exchanges (sces) suggest independent mechanisms for the two events despite some common features. examination of chromosome breakage caused by x-rays, visible light, and viruses has shown that few chromatid breaks are accompanied by sces at the sites of breaks. no similar observations were available for chemically induced breaks, but it has been reported that rat chromosomes exposed to dimethylbenzanthracene (dmba) contained a prepo ...197990339
somatic cell genetics of human interferon production in human-rodent cell hybrids.forty-two primary human-mouse cell hybrids, derived in two separate experiments, were treated with newcastle disease virus (ndv): eight hybrids were found to produce human interferon and this was shown in every case to be predominantly of the fibroblast type. an extensive analysis was made in terms of karyotype and marker enzymes on all the eight hybrids producing interferon and also on five hybrids which did not produce interferon, five randomly selected hybrids and eleven subclones resistant t ...197994346
absence of mutagenicity of praziquantel, a new, effective, anti-schistosomal drug, in bacteria, yeasts, insects and mammalian cells.praziquantel (embay 8440, droncit) a new, effective anti-schistosomal drug, was tested in various short-term assays that have shown a predictive value for the detection of potential carcinogens. indicator organisms s. typhimurium strains, s. pombe, s. cerevisiae, cultured v79 chinese hamster cells or human heteroploid cells and drosophila melanogaster were treated with praziquantel. the induction of reverse and forward mutations, mitotic gene conversions, x-linked recessive lethals, sister-chrom ...1978106268
identification of 7,12-dimethylbenz[a]anthracene metabolites that lead to mutagenesis in mammalian cells.the mutagenicity of 7,12-dimethylbenz[a]-anthracene (dmba) and 11 of its enzymatically derived metabolites was tested with chinese hamster v79 cells for identification of mutagenic metabolites. the metabolites consisted of 7-hydroxymethyl-12-methylbenz[a]anthracene, 7-methyl-12-hydroxymethylbenz[a]anthracene, 7,12-dihydroxymethylbenz[a]anthracene, three trans-3,4-diols, two trans-5,6-diols, and three trans-8,9-diols, all of which derived from dmba or from the hydroxymethyl derivatives. mutations ...1979106395
selective growth of some rodent epithelial cells in a medium containing citrulline.we have defined a medium (called sun's modified waymouth medium) that selectively cultures some rodent epithelial cells that are capable of using citrulline in place of arginine. a growth-response study of the ability of 47 different mammalian cell cultures (of mouse, rat, syrian hamster, chinese hamster, guinea pig, rabbit, monkey, and human origin) to use arginine or its biosynthetic precursors, ornithine, citrulline, or argininosuccinate, showed that all epithelial cells and some fibroblasts ...1979109834
comparison of mutagenesis and malignant transformation by dihydrodiols from benz[a]anthracene and 7,12-dimethylbenz[a]anthracene.five dihydrodiols derived from benz[a]anthracene (ba) and 4 dihydrodiols derived from 7,12-dimethylbenz[a]anthracene (dmba) have been tested, together with the parent hydrocarbons, for their abilities to induce mutations to 8-azaguanine resistance in v79 (chinese hamster cells and malignant transformation in m2 mouse fibroblasts. the syn- and anti-isomers of benz[a]anthracene 8,9-diol 10,11-oxide were also tested for biological activity in these two systems. the non-k-region 1,2- and 3,4-dihydro ...1979114201
assignment of structural beta-galactosidase loci to human chromosomes 3 and 22.hybrid cell lines isolated after fusions between chinese hamster e36 cells and normal human white blood cells were analyzed for human beta-galactosidase isoenzymes and for human chromosomes, especially 3, 12, and 22, the candidates for bearing a beta-galactosidase locus. results of neuraminidase treatment of the cell lysates and immunological studies showed that in man two structural beta-galactosidase loci are present and can be assigned to chromosomes 3 and 22. no correlation was found between ...1979116956
diabetogenic effects of n-nitrosomethylurea in the chinese hamster.to evaluate the role of the glucose residue of the diabetogenic substance streptozotocin, the effect of its aglucone derivate n-nitrosomethylurea was tested in chinese hamsters. at a dose of 50 mg/kg body weight of n-nitrosomethylurea a triphasic blood glucose curve was recorded with an initial hyperglycaemic peak after 3 hours followed by a decrease at 6 hours. after 24 hours and during the following days the values were moderately elevated. there was a high mortality in the diabetic animals, a ...1975125026
rate and time of dna synthesis of individual chinese hamster cells.the duration of dna synthesis of a diploid cell line of chinese hamster fibroblasts was determined in a comparative study by the flm technique, and also by a new technique for measuring the rate of dna synthesis of individual cells. these methods produced comparable results when applied during exponential growth of the cells. the rate of dna synthesis was measured by means of quantitative autoradiography following a short-term incubation of the cells with 5 x 10(-6) m fudr and 10(-5) m 14c-tdr. ...1975126804
mutation induction by the antischistosomal drug f30066 in various test systems.the genetic activity of furapromidium (f30066), an antischistosomal drug, was studied in salmonella typhimurium, saccharomyces cerevisiae, neurospora crassa and cultured chinese hamster cells. the results show that f30066 induces gene mutations in s. typhimurium, n. crassa and chinese hamster cells. this compound also causes gene conversions in s. cerevisiae.1977138086
human bronchus-mediated mutagenesis of mammalian cells by carcinogenic polynuclear aromatic hydrocarbons.cultured human bronchial explants activated benzo[alpha]pyrene (bzap) into electrophilic metabolites that bind to dna in bronchial epithelial cells. promutagenic and mutagenic metabolites of bzap were also released into the culture medium. an increase in mutation frequency for ouabain resistance was found in chinese hamster v-79 cells when they were cocultivated with bronchial explants in the presence of bzap. the proximate carcinogenic form of bzap, the 7,8-diol [(+/-)-r7,t8-dihyroxy-7,8-dihydr ...1978148049
liver cell-mediated mutagenesis of mammalian cells by liver carcinogens.a cell-mediated mutagenesis assay using primary cultures of rat liver cells and v79 chinese hamster cells has been developed. liver carcinogens and their structural analogues were studied. mutations in the v79 cells were characterized by resistance to ouabain. cocultivation of the liver cells and v79 cells in the presence of the carcinogens n-nitrosodimethylamine, n-nitrosodiethylamine, and aflatoxin b1 caused the induction of ouabain-resistant mutants of v79 cells. in the absence of liver cells ...1978149308
induction of sister chromatid exchanges by nicotinamide in chinese hamster lung fibroblasts and human lymphoblastoid cells. 1979160224
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 ...1975163374
detection by means of cell fusion of macromolecular synthesis involved in the reconstruction of the nuclear envelope in mitosis.using the cultured chinese hamster cell line don, g1 or s or a mixture of late-s/g2 cells were prepared by release from metaphase arrest. metaphase (m) cells were also obtained by mitotic arrest of log-phase cultures with colcemid and held in metaphase; such m cells remained untreated with any other compound and were termed standard m cells. when interphase (i) cells were fused at ph 8.0 and 37 degrees c with standard cells in the presence of colcemid by means of uv-inactivated sendai virus, bin ...1975163831
the effects of several croton oil constituents on two types of dna repair and cyclic nucleotide levels in mammalian cells in vitro.the purpose of the present study was to determine the effects of two potent tumor-promoting agents on two dna repair mechanisms and cyclic nucleotide levels in mammalian cells. human amnion (av3) cells were treated with low dose levels of either uv of n-acetoxy-acetylaminofluorene. subsequently, dna excision repair as measured by unscheduled dna synthesis was followed in the absence or presence of non-toxic levels of either 12-o-tetradecanoylphorbol-13-acetate (tpa), phorbol-12,13-dibenzoate (pd ...1975168978
site of synthesis of membrane and nonmembrane proteins of vesicular stomatitis virus.upon infection of chinese hamster ovary cells (cho), vesicular stomatitis (vsv) virus synthesizes two membrane proteins (the vsv glycoprotein and the vsv matrix or membrane (m) protein) and three nonmembrane proteins (the vsv nucleocapsid, the viral transcriptase, and an ns protein). we have used the vsv-infected cell as a model system for the study of the site of synthesis of these membrane and nonmembrane proteins. we have isolated vsv mrna from free polyribosomes, membrane-bound polyribosomes ...1975169263
a rapid electrophoretic technique for human and chinese hamster galactokinase. 1975170194
induction of gene mutations and chromosomal aberrations by simian virus 40 in cultured mammalian cells.induction of gene mutations by sv40 was studied in aneuploid human and chinese hamster cells. in chinese hamster cells sv40-induced chromosome aberrations were also studied. sv40 penetrated into the cells of both lines and induced synthesis of the t antigen. the efficiency of infection in chinese hamster cells was tested additionally by their ability to form colonies in medium lacking the serum growth factor. the maximal number of cells with serum growth factor independence was observed on the f ...1975172787
growth of enveloped rna viruses in a line of chinese hamster ovary cells with deficient n-acetylglucosaminyltransferase activity.sindbis and vesicular stomatitis viruses were grown in a line (termed 15b) of chinese hamster ovary (cho) cells that is deficient in a specific udp-n-acetyl-glucosamine:glycoprotein n-acetylglucosaminyltransferase. both viruses replicated normally in the cell line, but the glycoproteins of the released virus migrated faster on sodium didecyl sulfate-polyacrylamide gels than did glycoproteins of virus grown in parent cho cells. digestion of the viral glycoproteins with pronase followed by gel fil ...1975173886
the effects of serum concentration on the level of integration of simian virus (sv40) genome and the transformation frequency in sv40-infected chinese hamster cells. 1976174291
simian virus 40-chinese hamster kidney cell interaction. i. relationship of chromosome changes to transformation.after approximately 20 in vitro passages, chinese hamster kidney (chk) cell cultures transformed upon exposure to different strains of sv 40 can show a diploid modal chromosome number of 22 with chromosome counts exclusively or essentially in the diploid range (20-25). in primary culture and at the 5th-7th subculture, tumors produced in nude mice by such cells can display a diploid modal value of 22 chromosomes. numerical chromosome variations and karyotype abnormalities observed in chk cells tr ...1975174521
[stimulation of sv40 virus replication in chinese hamster kidney cells by treatment of the cells with mitomycin c].the production of virions by chinese hamster kidney cells infected with sv 40 dna is increased 10 to 100 fold by mitomycin c treatment. this observation has been confirmed for different cell clones. the optimum concentration of mitomycin c has been determined.1975174828
persistent reovirus infection of cho cells resulting in virus resistance.we obtained a persistently infected line of chinese hamster ovary cells by selection for resistance to reovirus infection. the cells were persistently infected by a population of viruses that were (i) cytopathic for parental chinese hamster ovary cells and (ii) similar to wild-type reovirus in molecular characteristics. the growth rate, plating efficiency, and morphology of the cells were altered. a large majority of the cells in the population were infected. there was no detectable interferon p ...1976176428
chromosomally depleted interspecific hybrid cell clones selected with cytotoxic antisera: utilization in the study of control of murine leukemia virus host-range.a chromosomally stable mouse-chinese hamster hybrid cell line was subjected to five rounds of selection with cytotoxic antisera raised in rabbits against either the parental mouse 3t3 cells or the parental chinese hamster wg-1 cells. routine karyological analysis of clones isolated at each stage of serum selection revealed that treatment with either serum resulted in a limited loss of chromosomes (compared to the untreated hybrid cell cultured in parallel) and that the pattern of chromosome loss ...1976176536
assignment of the ak1:np:abo linkage group to human chromosome 9.in man-chinese hamster somatic cell hybrids the segregation patterns of the loci for 25 human enzyme markers and human chromosomes were studied. the results provide evidence for the localization of the gene for adenylate kinase-1 (ak1) on chromosome 9. since the loci for the abo blood group (abo), nail-patella syndrome (np), and ak1 are known to be linked in man, the abo:np:ak1 linkage group may be assigned to chromosome 9.1976176661
simian virus 40-chinese hamster kidney cell interaction. ii. the semipermissivity of the cell system.throughout in vitro passages, chinese hamster kidney (chk) cells progressively lost susceptibility to sv 40 virus infection while remaining continuously susceptible to viral dna infection. upon infection with sv 40 virus or viral dna, the chk cell line supported viral dna and virus replication at a low level. sv 40 transformed chk cell lines spontaneously produced small amounts of viral dna and virions. the percentage of virus-producing cells was low. various clones derived from each of these li ...1976176967
enhanced sv 40-virus replication in chinese hamster kidney cells pretreated with 5-iodo-2'-deoxyuridine.sv40 virion production was enhanced when semipermissive chinese hamster kidney cells were treated with 5-iodo-2'-deoxyuridine (iudr), prior to infection either with virus or viral-dna. pretreatment did not increase sv40 replication in fully permissive monkey kidney and nonpermissive syrian hamster or mouse embryo cells.1976176975
[mutagenesis under the influence of simian vacuolating virus 40 (sv40). i. induction of chromosome aberrations in chinese hamster cells during the first days following infection].chromosome aberrations were studied in cultured chinese hamster cells on the 1--4th days after infection with simian virus 40. in the first and second mitoses after infection a statistically significant increase of the percentage of aberrant metaphases was observed (up to 22% as compared to 8--10% in intact cells). already after 3 days following treatment the percentage of aberrant metaphases decreased sharply, reaching the control level. the virus induced a significant increase of the frequency ...1975178571
[mutagenesis under the influence of simian virus 40 (sv40). ii. induct?ion of mutations resulting in resistance to purine base analogs in human and chinese hamster cells].induction of gene mutations by sv40 was studied in aneuploid human and chinese hamster cell lines. it is shown that sv40 penetrates into the cells studied and induces the t-antigen synthesis. the efficiency of the infection in chinese hamster cells was tested additionally by the ability of infected cells to form colonies in the medium lacking serum growth factor. the maximal number of colony-forming cells was detected 24 hours after the infection. by culturing cells in factor-free medium a chine ...1975178572
the induction of sv40-transformed chinese hamster and mouse kidney cells by mitomycin c.the induction by mitomycin c (mc) of sv40 production in three lines of semi- or nonpermissive sv40-transformed cells is described. the production of virions by a line of semipermissive, virus-shedding chinese hamster kidney cells is increased 1,000-fold by mc treatment; the proportion of infectious centers and v-antigen-containing cells is increased to a lesser degree, suggesting that both the burst per cell and the number of virus-producing cells are increased. mc treatment induces the producti ...1975178625
resting state in normal and simian virus 40 transformed chinese hamster lung cells.normal cell deprived of amino acids or serum factors enter a resting state, whereas cells transformed by wild-type simian virus 40 do not. the ability to enter a resting state is temperature-sensitive (ts) in cells transformed by a tsa mutant of simian virus 40. we shown further: (i) that when complete medium is added to resting cells, the length of time until the onset of dna synthesis often exceeds the length of g1 in growing cells; (ii) that the length of this interval depends upon the condit ...1976179093
[protective effect of thymidine in relation to the cytostatic action of cyclic adenosine-3', 5'-monophosphate in mammalian cell cultures].under the action of lmm of cyclic adenosine-3',5'-monophosphate (camp) the survival and the rate of reproduction of the cells of chinese hamster in the culture decreased in comparison with control to 27 and 42%, respectively. addition of 0.02 mm thymidine together with camp almost completely eliminated the cytostatic action of the latter. thymidine also prevented the cytostatic effect of noncyclic 5'-amr, but failed to influence the death of the cells with the action of dibutyril camp and theoph ...1975179557
laboratory investigation of diarrhea in travelers to mexico: evaluation of methods for detecting enterotoxigenic echerichia coli.a laboratory investigation was conducted on cultures collected from travelers before, during, and after a trip to mexico to characterize the etiology of traveler's diarrhea. four laboratory methods for detecting enterotoxigenicity of escherichia coli were evaluated: the infant mouse assay, the chinese hamster ovary (cho) cell assay, the y1 adrenal cell assay, and the rabbit ileal loop. although a number of common enteric pathogens were identified as a cause of traveler's diarrhea, including six ...1976180047
the selection of virus-resistant chinese hamster ovary cells.we have selected chinese hamster ovary (cho) cells resistant to infection by encephalomycarditis (emc) virus. thus far, we have obtained five lines resistant to emc, all of which manifest different phenotypes. three of the five are not persistently infected with virus, while two lines produce infectious virus and grow in its presence. the nonpersistently infected lines exhibit different resistance profiles to the other viruses we have tested, and they are stable in nonselective growth conditions ...1976182382
[mutagenesis under the influence of simian virus 40 (sv40). ii. induction of mutations for resistance to analogs of purine bases in human and chinese hamster cells].induction of gene mutations by sv40 was studied in aneuploid human and chinese hamster cell lines. it is shown that sv40 penetrates into the cells studied and induces the t-antigen synthesis. the efficiency of the infection in chinese hamster cells was tested additionally by the ability of infected cells to form colonies in the medium lacking serum growth factor. the maximal number of colony-forming cells was detected 24 hours after the infection. by culturing cells in factor-free medium a chine ...1975182615
mutagenesis by simian virus 40. i. detection of mutations in chinese hamster cell lines using different resistance markers.the mutagenic action of sv40 in permanent lines of chinese hamster cells (cho-k1 and v79) was investigated with the aid of different resistance markers. the markers studied had resistance to 8-azaguanine (25 and 30 mug/ml), aminopterin (3.3--5.5x10(-3) mug/ml), colchicine (6.5 and 7.0x10(-2) mug/ml) and 5-bromodeoxyuridine (50--120 mug/ml), respectively. after virus infection the mutation frequencies were increased by one (azaguanine, aminopterin) and two (colchicine) orders of magnitude as comp ...1976184380
confirmation of the assignment of the locus determining ada to chromosome 20 in man: data on possible synteny of ada and itp in human-chinese hamster somatic cell hybrids. 1976185012
chromosomal assignment of the gene for human red cell adenylate kinase (ak1) in man-chinese hamster somatic cell hybrids. 1976185020
simian virus 40 mutants carrying two temperature-sensitive mutations.five temperature-sensitive mutants of simian virus 40 containing two temperature-sensitive mutations were isolated. the double mutant of the a and d complementation groups, like the d mutants, failed to complement by conventional complementation analysis and did not induce host dna synthesis at 40 degrees c. however, under conditions that suppressed the d defect, the a:d double mutant expressed only the a defect. thus, viral dna replication dropped rapidly after this mutant was shifted from perm ...1976185417
evolutionary trends in 18s ribosomal rna nucleotide sequences of rat, mouse, hamster and man.the large t1 ribonuclease fragments of 18s ribosomal rna from four mammalian species, rat, mouse, hamster and man, were compared by two-dimensional homochromatography fingerprinting. the nucleotide sequences of the large t1 ribonuclease fragments, polypyrimidines and polypurines which were different among the four mammalian species were determined and compared. the method used for determining nucleotide sequences utilizes 32p-labeling of oligonucleotides at their 5'-termini by polynucleotide kin ...1976188015
assembly of viral membranes. i. association of vesicular stomatitis virus membrane proteins and membranes in a cell-free system.we report here an in vitro system designed to study the interactions of vesicular stomatitis virus (vsv) proteins with cellular membranes. we have synthesized the vsv nucleocapsid (n) protein, nonstructural (ns) protein, glycoprotein (g protein), and membrane (m) protein in a wheat germ, cell-free, protein-synthesizing system directed by vsv 12 to 18s rna. when incubated at low salt concentrations with purified cytoplasmic membranes derived from chinese hamster ovary cells, the vsv m andg protei ...1977189082
assignment of the integration site for simian virus 40 to chromosome 17 in gm54va, a human cell line transformed by simian virus 40.gm54va human cells transformed by simian virus 40 (sv40) were fused with peritoneal macrophages obtained from three different mouse strains. all 27 hybrid clones studied were positive for sv40 tumor antigen in 100% of their cells and contained human chromosome 17. human chromosome 17 was the only human chromosome present in five of the hybrid clones. fusion of gm54va cells and either thymidine kinase (ec 2.7.1.75)-deficient mouse or chinese hamster fibroblasts resulted in the growth in hypoxanth ...1977189310
variation in enterotoxigenicity of escherichia coli.the possibility that the variable severity of diarrheal disease due to enterotoxigenic escherichia coli might be explained by quantitative differences in the activity of heat-labile enterotoxin was examined. the amount of toxin secreted by 13 enteropathogenic strains of e. coli was quantitated by measurements of the toxin-dependent increase in adenosine 3':5'-cyclic phosphate (cyclic amp) in chinese hamster ovary cells. the activity ranged from 150 pmol of cyclic amp/ml per mg of protein to 4,04 ...1977190329
chromosomal assignment of the gene for human red cell adenylate kinase (ak1) in man-chinese hamster somatic cell hybrids. 1976192371
heterogeneity of karyotype and growth potential in simian virus 40-transformed chinese hamster cell clones.five clones of chinese hamster cells transformed with simian virus 40 (sv40) were isolated from methylcellulose and characterized as to giemsa-banded karyotype, dna content, saturation density, agglutination with concanavalin a, and tumorigenicity. chromosome analysis and dna content studies at early passage revealed that the genetic complement for all clones was predominantly near tetraploid. all cultures examined contained a proportion of hypertetraploid cells. nonrandom chromosome changes inc ...1977192902
effects of temperature and antibody on the cyclid growth of vesicular stomatitis virus.to see the effects of temperature on the interrelated cyclic production of standard and defective interfering (di) particles of vesicular stomatitis virus, a temperature-sensitive (ts) g114 mutant was passaged successively at different temperatures and the production of the two types of viral particles as well as the ability of chinese hamster ovary cells to survive each passage was continuously monitored. when the temperature was nonpermissive for standard virus, the synthesis of both standard ...1977189064
simian virus 40-chinese hamster kidney cell interaction. iii. characteristics of chemical induction in a clone of virogenic transformed cells.a number of chemical and physical agents were screened to determine their effectiveness in inducing simian virus (sv40) production in a virogenic clone of sv40-transformed chinese hamster cells. mitomycin c (mc) was the most effective inducing agent, and mc induction was further characterized. it was found that levels of infectious sv40 dna were increased above control levels as early as 6 h after addition of mc to the culture medium and reached maximum levels by 48 h. virus capsid (v) antigen a ...1977196036
simian virus 40-chinese hamster kidney cell interaction. iv. enhanced virus replication in infected cells upon treatment with mitomycin c.chinese hamster kidney cells are semi-permissive to simian virus 40 (sv40). exposure to mitomycin c (mc) of chinese hamster kidney cells infected with sv40 dna enhanced the yield of infectious virus 10- to 100-fold. this stimulation occurred whether the treatment was performed before or after infection. a simultaneous increase in the number of v antigen-synthesizing cells and virus-producing cells, as well as the virus burst size, was observed upon mc pretreatment, whereas the proportion of t an ...1977196038
correlation between changes in intracellular level of cyclic amp, activation of cyclic amp-dependent protein kinase, and the morphology of chinese hamster ovary cells in culture. 1977196552
initiation points for dna replication in nontransformed and simian virus 40-transformed chinese hamster lung cells.randomly growing chinese hamster lung cells were pulse-labeled with 3h-thymidine, and the replicating forks of individual dna fibers were visualized by autoradiography. when grown in complete medium, wild-type sv40-transformed cells had more forks per unit length of dna than nontransformed cells. in isoleucine-depleted medium, wild-type sv40-transformed cells had fewer forks per unit length than those few nontransformed cells (1-3% of the population) which continued dna replication. cells transf ...1977196764
synteny of the genes for thymidine kinase and galactokinase in the mouse and their assignment to mouse chromosome 11.we have studied the expression of mouse galactokinase in human-mouse somatic cell hybrids segregating mouse chromosomes. since concordant segregation of the expression of mouse galactokinase and the presence of mouse chromosome 11 were observed in the hybrid clones, we conclude that the gene for mouse galactokinase is located on mouse chromosome 11. we have also investigated the expression of mouse galactokinase in somatic cell hybrids between thymidine kinase-deficient chinese hamster cells and ...1977196814
effect of staphylococcus aureus delta toxin on chinese hamster ovary cell morphology and y-1 adrenal cell morphology and steroidogenesis.since staphylococcus aureus delta toxin previously had been shown to increase the cyclic adenosine 3',5'-monophosphate (camp) content of guinea pig ileum, the effect of delta toxin on such camp-mediated responses as morphogenesis and steroidogenesis in cultured tissue cells was examined. in contrast to cholera toxin, delta toxin did not cause spindling of chinese hamster ovary cells. unlike adrenocorticotropin or cholera toxin, delta toxin was unable to cause rounding of y-1 adrenal cells or to ...1977197006
gene mapping in mus musculus by interspecific cell hybridization: assignment of the genes for tripeptidase-1 to chromosome 10, dipeptidase-2 to chromosome 18, acid phosphatase-1 to chromosome 12, and adenylate kinase-1 to chromosome 2.chinese hamster x mouse somatic cell hybrids segregating mouse chromosomes were examined for their mouse chromosome content using trypsin-giemsa (gtg) banding and hoechst 33258 staining techniques. simultaneously, they were scored for the presence of 24 mouse enzymes. the results confirm the assignments of 11 genes previously mapped by sexual genetics: dip-1 and id-1 to chromosome 1; pgm-2 and pgd to 4; pgm-1 to 5; gpi-1 to 7; gr-1 to 8; mpi-1 and mod-1 to 9; np-1 and es-10 to 14. they also conf ...1977198184
chromosomal alterations in a chinese hamster cell line transformed in vitro by sv40 virus. 1977200554
a comparison of camp phosphodiesterases in normal, malignant, and somatic cell hybrids.hybrids (pcm) between a malignant mouse lymphoma suspension cell line (p388f-36) and a normal chinese hamster fibroblastic cell line (ch23) have already been isolated in this laboratory. investigations were carried out on the camp phospodiesterases of the parents and two of these hybrids--pcm2 and pcm3. pcm3 shows a rather unusual growth characteristic in that a considerable proportion of the cells exist at any one time either in suspension or only loosely attached to the substratum, the remaini ...1977201244
an investigation of the homology of guanylate kinase isozymes in mammals and further evidence for multiple guk gene loci.guanylate kinase in the red cells of 63 different mammalian species was studied by electrophoresis and multiple molecular forms of the enzyme were found in all species. two species were investigated in more detail. using molecular weight estimates as a criterion of homology, the fallow deer and the chinese hamster were found to have isozymes that corresponded to isozyme e, f, and g of man. variation in the guanylate kinase isozymes was detected in a small population of orangutans. results sugges ...1977201245
virus production with a newly developed microcarrier system.primary cell cultures as well as established lines have been grown on a recently developed microcarrier configuration that overcomes the problem of toxicity attendant on earlier developments in this technology. virus yields from these cells propagated on the new microcarriers have been measured. microcarrier-grown cells, when compared to roller-bottle-grown cells, gave virus yields on a per-cell basis that varied from slightly greater with the sindbis virus-chinese hamster ovary cells and polio- ...1977202193
assignment of the genes for thymidine kinase and galactokinase to mus musculus chromosome 11 and the preferential segregation of this chromosome in chinese hamster/mouse somatic cell hybrids. 1977204065
transformation of chinese hamster embryo cells with an avian sarcoma virus ts mutant.chinese hamster embryo cells were transformed with temperature-sensitive mutant of the schmidt-ruppin strain of rous sarcoma virus-subgroup a (ts ny68s ra-a). the developed cell line elicited the morphological transformation at a permissive temperature of 35 degrees c, whereas after a shift to a non-permissive temperature of 40 degrees c the cells reverted to a normal phenotype. tests for the presence of avian sarcoma group-specific antigen showed that the antigen was not expressed both at permi ...1976186335
expression of "early" and "late" viral functions in a somatic cell hybrid between a mouse cell and a spontaneous yielder sv 40-transformed chinese hamster cell.a somatic cell hybrid (cl. 6d) was originated from the fusion of mouse 3t3-4e) and spontaneous yielder sv 40-transformed chinese hamster (chk/svlp ag) cells. during the early stages of its history, the c1. 6d hybrid underwent a rapid chromosome loss, preferentially loosing hamster chromosomes. this was not a constant tendency of the hybrid cells. as the parental chk)svlp ag cells, the hybrid cells were always found 100 per cent sv40 t-antigen positive. while chk/svlp ag cells infectious sv 40 dn ...1978204268
[transmission and expression of malignancy in somatic hybrid cell lines (hamster/hamster, mouse/mouse, hamster/mouse)].various characteristics of transformation were studied in subclones isolated from a hybrid cell line obtained by fusion of two chinese hamster sub-lines having the same origin but presenting different properties, particularly in respect to heterotransplantability. different subclones were obtained by cloning on semisoft agar. transplantability, plating efficiency, agglutinability by concanavalin a and actinomycin d resistance were studied in parallel with the evolution of the karyotype to try to ...1976186142
cotransfer of thymidine kinase and galactokinase genes by chromosome-mediated gene transfer.the chinese hamster genes for thymidine kinase (atp:thymidine 5'-phosphotransferase, ec 2.7.1.75) and galactokinase (atp:d-galactose 1-phosphotransferase, ec 2.7.1.6) have been cotransferred to mouse cells by chromosome-mediated gene transfer. hamster metaphase chromosomes were incubated with mouse b82 cells and 22 independent colonies were isolated in a selective medium. all of the 12 colonies analyzed expressed the donor form of thymidine kinase; the hamster form of galactokinase was also expr ...1978204939
assignment of the gene for adenosine kinase to chromosome 14 in mus musculus by somatic cell hybridization.evidence is presented for the assignment of the gene for adenosine kinase to mus musculus chromosome 14 by synteny testing and karyotypic analysis of mouse x chinese hamster somatic cell hybrid clones. adok and two enzymes previously mapped to mouse chromosome 14, np and es-10, were expressed concordantly in 29 hybrid clones. chromosome analysis confirmed this assignment. syntenic evidence is also presented using several clones of a gene transfer system in which the gene for human hprt had integ ...1978206412
a host range difference between herpes simplex virus types 1 and 2.the infectivities of several strains of herpes simplex virus type 1 and type 2 were measured by plating on established human and chinese hamster cell lines. whereas all the type 1 strains reproducibly showed a 10(4)-fold lower titre on the chinese hamster cells, the type 2 strains showed only a 10- to 100-fold lower titre. this host range difference has been used in the analysis of recombinants between type 1 and type 2 viruses.1978206659
specific changes in the oligosaccharide moieties of vsv grown in different lectin-resistnat cho cells.the carbohydrate moieties of the g glycoprotein of vesicular stomatitis virus (vsv) grown in three distinct lectin-resistant (lecr) chinese hamster ovary (cho) cell lines have been compared by fine structural analysis of radiolabeled glycopeptides. the mutant wgariii, selected for resistance to wheat germ agglutinin (wga), produces vsv containing g glycoprotein specifically lacking in sialic acid. the mutant phari, selected for resistance to phytohemagglutinin (pha) and previously shown to lack ...1978207434
ultrastructural study of the adenohypophysis of the chinese hamster.the adenohypophysis of normal chinese hamsters of both sexes was examined ultrastructurally. organs were fixed by intravascular perfusion with s-collidine-buffered glutaraldehyde solution. seven types of cells were differentiated and, according to morphological characteristics, classified as (1) mammotropes, with very large (400-800 nm) polymorphous secretory granules; (2) somatotropes, either in the storage phase with numerous large, dense granules (average 300 nm), or in the hormone synthesis ...1976184639
induction by short-chain fatty acids of alkaline phosphatase activity in cultured mammalian cells.short-chain fatty acids, such as propionic, n-butyric, n-butyric, n-valeric, isovaleric, n-caproic, and n-caprylic acids, induce alkaline phosphatase activity in cultured mammalian cells. long-chain fatty acids have no similar effects. with b-6 cells (mouse x chinese hamster cell hybrids), n-butyrate at 2 to 5 mm exhibits the greatest activity. induction begins exponentially about 24 hours after addition of the fatty acid and continues over 48 hours. studies on the inducing activity-structure r ...1976177433
aanlysis of dcmp deaminase and cdp reductase levels in hamster cells infected by herpes simplex virus.several enzymatic activities involved in the biosynthetic pathways of nucleotides, including thymidine kinase, which has been used as a biochemical marker in studies of gene transfer, are induced by herpes simplex virus (hsv). the utility of additional markers prompted us to reanalyze the effects of hsv infection on the activities of two other enzymes for which direct selective methods can be devised: dcmp deaminase and cdp reductase. for this purpose, mutant chinese hamster (la1) cells devoid o ...1978209209
molecular dosimetry of the chemical mutagen ethyl methanesulfonate in escherichia coli and in v-79 chinese hamster cells. 1978209321
homologous genes for enolase, phosphogluconate dehydrogenase, phosphoglucomutase, and adenylate kinase are syntenic on mouse chromosome 4 and human chromosome 1p.it is possible to generate interspecific somatic cell hybrids that preferentially segregate mouse chromosomes, thus making possible mapping of mouse genes. therefore, comparison of the linkage relationships of homologous genes in man and mouse is now possible. chinese hamster x mouse somatic cell hybrids segregating mouse chromosomes were tested for the expression of mouse enolase (eno-1; ec 4.2.1.11, mckusick no. 17245), 6-phosphogluconate dehydrogenase [pgd; ec 1.1.1.44, mckusick no. 17220], p ...1978209463
new region of the simian virus 40 genome required for efficient viral transformation.viable mutants of simian virus 40 with deletions in three regions of the virus genome (map coordinates 0.21-0.17, 0.59-0.54, and 0.67-0.74) have been tested for their ability to transform rat fibroblasts to anchorage independence. only those mutants whose deletions occur between 0.59 and 0.55 in the proximal part of the early region are defective in transforming ability. the most severely defective of these transform with less than one-hundredth the efficiency of wild type. they retain their def ...1978209467
reexpression of hprt activity following cell fusion with polyethylene glycol.polyethylene glycol-1000 (peg-1000) induced fusion of hprt (e.c. 2.4.2.8) deficient chinese hamster cells with alpha-galactosidase a (e.c. 2.3.1.22) deficient cells from a patient with fabry's disease yielded hybrids which contained both human and hamster hprt, g6pd (e.c. 1.1.1.49), and aprt (e.c. 2.4.2.7) and chinese hamster alpha-galactosidase b. thus peg-1000 mediated somatic cell fusion led to reexpression of chinese hamster hprt. it did not restore the expression of human alpha-galactosidas ...1978209782
cyclic amp and insulin release.the role of cyclic adenosine-3',5'-monophosphate (camp) for insulin secretion has been investigated. in isolated islets of langerhans from the rat, glucose increases camp concomitant with insulin secretion. stimulation of these two parameters is likewise reversible in parallel. the minimal and maximal concentrations of glucose eliciting camp and insulin responses are similar. isomers and epimers of glucose influence insulin and camp in a parallel fashion as do sulfonylurea compounds (tolbutamide ...1977210617
thermolabile t (tumor) antigen from cells transformed by a temperature-sensitive mutant of simian virus 40.partially purified tumor (t) antigen from a strain of chinese hamster lung cells transformed by wild-type simian virus 40 (sv 40) and either of two temperature-sensitive sv 40 mutants has been studied as a dna binding protein. the dna binding activity present in the t-antigen-containing fractions is inhibited by purified hamster anti-t igg but not by equivalent amounts of nonimmune hamster igg. t from either wild-type- or tsc219-transformed cells is relatively stable during heating at 44 degrees ...1975172906
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