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cellular and chemical reduction products of misonidazole.misonidazole is readily reduced by zinc dust in aqueous solution in the presence of ammonium chloride. high pressure liquid chromatographic (hplc) separation of the reduction mixture revealed the presence of three products. these were identified as the hydroxylamine, amine and the hydrazo derivative of misonidazole. there is evidence that the azoxy derivative was an intermediate in the reduction process. when the reduction was carried out in dilute solution (0.1 mg/ml), the hydroxylamine was the ...19817273240
hybrid clones of rat liver and hamster ovary cells as targets for carcinogen screening.many short-term carcinogen-screening assays use transformed cells which require exogenous metabolizing systems to activate carcinogens. we have sought untransformed target cell-lines with a high mitotic index and the intrinsic ability to metabolize carcinogens. hybrid cell clones were established by fusing an untransformed rat liver cell-line (with a normal diploid karyotype, epithelial morphology and carcinogen-metabolizing capacity) and a chinese hamster ovary cell-line (with a high mitotic in ...19817273288
factors influencing the induction of sister chromatid exchanges in mammalian cells by 12-o-tetradecanoyl-phorbol-13-acetate.the induction of sister chromatid exchanges (sce) by 12-o-tetradecanoyl-phorbol-13-acetate (tpa) was measured in mouse 10t1/2 and 3t3 cells released from density; inhibition, and chinese hamster cho cells synchronized by mitotic selection. the induced frequency of sce was similar in each cell type, but depended upon the concentration of tpa employed, its source, and the particular lot from the same source. most sce occurred in the first two rounds of cell replication after addition of tpa. the i ...19817273339
[characteristics of an interspecies somatic hybrid (chinese hamster x mouse)].an interspecific somatic hybrid between the biochemically marked cell lines of chinese hamster (m-15-1) and mouse (b-82) was obtained. morphology of the hybrid, its karyotype characteristics in the 9-th and 22-nd passages, as well as kinetics of growth were studied. periods of doubling of the hybrid cells, the chinese hamster m-15-1 cells and the mouse b-82 cells proved to be 26, 18 and 21 h, respectively. it was revealed, that elimination of chromosomes took place in the course of the hybrid ce ...19817195857
induction of chromosomal aberrations and sister-chromatid exchanges in chinese hamster cells in vitro by some proximate and ultimate carcinogenic arylamide derivatives.the carcinogenic compounds n-hydroxy-n-acetyl-2-aminofluorene, n-acetoxy-n-acetyl-2-aminofluorene, n-hydroxy-n-acetyl-4-aminobiphenyl and n-acetoxy-n-acetyl-4-aminobiphenyl were studied for their ability to induce chromosomal aberrations and sister-chromatic exchanges in chinese hamster ovary cells in the presence and absence of a rat-liver microsomal system. the o-acetates of n-hydroxy-n-acetyl-2-aminofluorene and n-hydroxy-n-acetyl-4-aminobiphenyl induced chromosomal aberrations in a populatio ...19817195981
assignment of genes to the human x chromosome by the two-dimensional electrophoretic analysis of total cell proteins from rodent-human somatic cell hybrids.the technique of two-dimensional (2-d) gel electrophoresis was sued to identify five human x-linked gene products in crude cell extracts of mouse-human and chinese hamster-human somatic cell hybrids. the human origin of these five polypeptides was demonstrated by their comigration with human fibroblast proteins and their failure to comigrate with polypeptides in extracts from the mouse or hamster parental cells. all five polypeptides were present in extracts of rodent-human hybrids that containe ...19817196152
rates of incorporation of radioactive molecules during the cell cycle.we report measurements of the incorporation of radioactive molecules during short labeling periods, as a function of cell-cycle stage, using a cell-sorter-based technique that does not require cell synchronization. we have determined: (1) tritiated thymidine (3h-tdr) incorporation throughout s-phase in lewis lung tumor cells in vitro both before and after treatment with cytosine arabinoside; (2) 3h-tdr incorporation throughout s-phase in kht tumor cells in vitro and in vivo; (3) 3h-tdr incorpora ...19817196407
inhibition of clonogenic growth of melanoma cells by combination of melanocyte stimulating hormone and theophylline.the combination of msh and theophylline is synergistic in inhibiting the growth as well as stimulating the differentiation of pigmented melanoma cells. in order to determine if a permanent alteration in the proliferative potential of these cells was achieved, we examined the effect of msh and theophylline alone and in combination upon the plating efficiency and tumorigenicity of s-91 cloudman melanoma cells. following treatment with the combination of msh and theophylline, the cells became deepl ...19817196427
chinese hamster ovary chromosomes and antigens in tobacco/hamster heterokaryons.tobacco ggll/hamster cho hamster heterokaryon frequency following cell fusion has been raised to 4-10 percent with a modified peg procedure. in heterokaryons, ggll nuclei become activated, adhere to and appear to fuse with cho nucleo. metaphase cho chromosomes can be identified 24 hours after fusion and immunofluorescent cho cell surface antigens diffuse into the plant cell membrane. diffusion coefficients, d, are estimated to be between 0.6 x 10(-11) and 1.6 x 10(-11) cm2sec-1.19817196927
assignment of the gene coding for phosphoribosylglycineamide formyltransferase to human chromosome 14.purine-requiring chinese hamster ovary cell auxotrophs of the complementation class ade-e were hybridized with various human cells, and hybrids were isolated under selective conditions in which the retention of the complementing gene on the human chromosome is necessary for survival. synteny analysis in 72 primary and secondary hybrid clones using isozyme, karyotypic, and biochemical methods provides evidence for an assignment of the gene for phosphoribosylglycineamide formyltransferase (gart, e ...19817197058
oncogenic adenovirus as mutagen for chinese hamster cells in vitro.oncogenic bovine adenovirus (bav3) was shown to induce chromosome aberrations and gene mutations to 6-mercaptopurine (6mp) resistance in chinese hamster cells. bav3 showed the highest mutagenic effect at the chromosome level 12--24 h postinfection. after 48 h the yield of aberrations dropped to the control level, where it remained after 72 and 96 h. bav3 showed a highly significant induction of mutations to 6mp resistance 48 h postinfection. the effect of the combined treatment of cells with 5-b ...19817197400
constitutive behavior of methionyl-trna synthetase compared to repressible behavior of methionine adenosyltransferase in mammalian cells.methionine adenosyltransferase, one of the two major enzymes utilizing methionine, is regulated by the levels of methionine in the growth medium (jacobsen, s.j., hoffman, r.m. and erbe, r.w. (1980) j. natl. cancer inst. 65, 1237--1244, and caboche, m. and mulsant, p. (1978) somatic cell genet. 4, 407--421). we report here that methionyl-trna synthetase, unlike methionine adenosyltransferase, behaves in a constitutive manner with respect to the concentration of methionine in the culture medium. t ...19817197557
clastogenicity of furans found in food.cultured chinese hamster ovary (cho) cells were exposed for 3 h to furan and 6 furan derivatives (furfural, furfuryl alcohol, 5-methyl furfural, 2-methyl furan, 2,5-dimethyl furan and 2-furyl methyl ketone). each of the 6 furan derivatives induced a relatively high frequency of chromatid breaks and chromatid exchanges in the absence of a liver microsomal activation preparation. the response of the furans to the addition of an s9 mixture differed. the clastogenic activities of 5-methyl furfural, ...19817198003
[frequency of aberrations in uni- and biliary 5-bromodeoxyuridine-substituted chromatids].chinese hamster cells and human lymphocytes were incubated with brdurd during two cycles of replication and stained using the "harlequine" technique. the g2 cells were irradiated with 1 gy of gamma-rays from the 60 co source. the frequency of breaks in light (i.e. bifiliary substituted) chromatids was significantly lower, as compared with dark (i.e. unifiliary substituted) ones. the comparison of these data with the previously published suggests that the relative frequency of breaks in uni- and ...19817198600
role of concanavalin a as an endocytic modulator in chinese hamster ovary cells.the effect of the lectin, concanavalin a (con a), on pinocytic uptake and pinosome-lysosome fusion in chinese hamster ovary (cho) cells, a fibroblast line, was investigated. the glycosylated protein, horseradish peroxidase (hrpase), and the non-glycosylated protein, 125i-labelled bovine serum albumin ([125i]bsa), was used as endocytic tracers. con a at high concentrations (greater than or equal to 50 micrograms/ml) promoted the uptake of hrpase and inhibited the degradation of ingested hrpase. c ...19817198643
chromosomal damage induced by furocoumarins and uva in hamster and human cells including cells from patients with ataxia telangiectasia and xeroderma pigmentosum.the comparative photosensitizing effects to near-uv irradiation (uva) of several naturally occurring furocoumarins, 5-methoxypsoralen (5mop), psoralen, 8-methoxypsoralen (8mop) and angelicin in producing chromosome damage in vitro in cells derived from hamster, normal human, ataxia telangiectasia (at) and xeroderma pigmentosum (xp) patients were studied. in chinese hamster cells, lethality was greatest with psoralen and least with angelicin; 8mop and 5mop were intermediate. 8mop and 5mop produce ...19817199114
effect of calcium phosphate and alumina c gamma gels on the mutagenicity and cytotoxicity of dimethylnitrosamine as studied in the cho/hgprt system.when cacl2 was added in increasing concentrations to a rat liver metabolic activation system (s9) buffered with sodium phosphate, the mutagenic activity and cytotoxicity of dimethylnitrosamine (dmn) in the chinese hamster ovary cell/hypoxanthine-guanine phosphoribosyl transferase (cho/hgprt) system were greatly increased. this effect was not observed with an s9 mix buffered with n-2-hydroxyethylpiperazine-n'-2-ethanesulfonic acid (hepes). the calcium phosphate gel precipitate of the s9 mix posse ...19817199116
chromosome-damaging activity of ferritin and its relation to chelation and reduction of iron.ferritin from horse spleen was found to cause severe chromosome aberrations in cultured chinese hamster ovary cells. ferritin at 15 to 170 microgram/ml was clastogenic and at higher doses was cytotoxic. at comparable concentrations of protein or iron, neither apoferritin nor complexed iron was clastogenic. sulfhydryl compounds glutathione and cysteine reduced the cytotoxic and clastogenic activities of ferritin. physiological concentrations of glutathione may normally be sufficient to protect ce ...19817194142
role of deoxynucleoside triphosphate pools in the cytotoxic and mutagenic effects of dna alkylating agents.the objective of these studies was to define the role of deoxynucleoside triphosphate pools in the cytotoxic and mutagenic effects of dna alkylating agents. survival of chinese hamster ovary (cho) cells after treatment with dna alkylating agents was clearly related to the balance of the dctp and dttp pools--high dctp/dttp ratios increased the survival of cho cells 2- to 10-fold compared to treatment in low dctp/dttp. induction of mutations at three genetic loci by one agent, ethyl methane sulfon ...19817194519
microheterogeneity among carbohydrate structures at the cell surface may be important in recognition phenomena.independently derived mutants of chinese hamster ovary cells have been isolated and shown to exhibit a subtle glycosylation defect resulting in the premature termination of certain asparagine-linked carbohydrate moieties. this carbohydrate alteration is akin to the types of structural variation termed microheterogeneity and is thought not to affect the biological activities of glycoproteins that manifest the phenomenon. however, the carbohydrate change expressed by the mutants is stable and heri ...19817194740
growth factor requirements of chinese hamster lung fibroblasts in serum free media: high mitogenic action of thrombin.we have defined a chemical medium to grow an anchorage and highly serum-dependent chinese hamster lung fibroblast cell line (ccl 39) in the absence of serum. this serum-free medium referred to as dm4, contains transferrin (5 microgram/ml), insulin (10 microgram/ml), epidermal growth factor (10 ng/ml) and thrombin (0.05 u/ml). thrombin appeared to be a very potent mitogen for chinese hamster lung cells. dm4 allows exponential growth of ccl 39 cells plated in serum-coated dishes without any lag an ...19817194743
chinese hamster ovary cells replicate adenovirus deoxyribonucleic acid.chinese hamster ovary (cho) cells infected with adenovirus type 2 (ad2) produced amounts of viral deoxyribonucleic acid (dna) equal to that synthesized in permissively infected hela cells. however, there was 6,000-fold less virion produced in cho cells. since the structural viral polypeptides were not detected by pulse-labeling cho cells at various times postinfection, the block in virion formation is located between the synthesis of viral dna and late proteins. extracts of cho cells could also ...19816965097
permeabilization of ultraviolet-irradiated chinese hamster cells with polyethylene glycol and introduction of ultraviolet endonuclease from micrococcus luteus.chinese hamster v-79 cells were made permeable by treatment with polyethylene glycol and then incubated with a micrococcus luteus extract containing ultraviolet-specific endonuclease activity. this treatment introduced nicks in irradiated, but not in unirradiated, deoxyribonucleic acid. the nicks remained open for at least 3 h; there was no loss of endonuclease-sensitive sites, and no excision of dimers as measured by chromatography was detected. in addition, there was no increase in ultraviolet ...19816965098
enhancement of cytotoxicities of ricin and pseudomonas toxin in chinese hamster ovary cells by nigericin.nigericin and monensin, ionophores for na+ and k+, have been found to enhance the cytotoxicities of abrin, ricin, and pseudomonas aeruginosa exotoxin a in chinese hamster ovary (cho) cells. they do not affect the cytotoxicity of diphtheria toxin in the same cell line. maximal sensitization of the cho cells toward ricin and pseudomonas toxin requires preculture of cho cells in the presence of nigericin. inhibition of protein synthesis in cho cells by ricin or pseudomonas toxin is also enhanced by ...19816965108
modified elek test for detection of heat-labile enterotoxin of enterotoxigenic escherichia coli.the elek test was modified for detection of the heat-labile enterotoxin of enterotoxigenic escherichia coli. a total of 164 strains of e. coli were tested by the modified elek test, and the results correlated well with those of the chinese hamster ovary cell assay and passive immune hemolysis. it is concluded that the modified elek test is a simple and reproducible assay method for identification of e. coli which produce heat-labile enterotoxin, and is suitable for use in clinical laboratories.19816780599
facilitated transport of inosine and uridine in cultured mammalian cells is independent of nucleoside phosphorylases.the zero-trans uptake of uniformly and base-labeled inosine and uridine was measured a 25 degrees c in suspensions of novikoff rat hepatoma cells, chinese hamster ovary cells, mouse l cells, mouse s49 lymphoma cells and a purine-nucleoside phosphorylase-deficient subline thereof (nsu-1), and in monolayer culture of mouse 3t3 and l cells. the initial velocities of uptake of both nucleosides were about the same in all cell lines investigated, regardless of the position of the label or of the subst ...19816783140
comparative gene mapping of man and cebus capucinus: a study of 23 enzymatic markers.a total 23 enzymatic markers were analyzed in cell hybrids obtained between cebus capucinus (cca) fibroblasts and a chinese hamster cell line. the following markers, or syntenic groups, could be localized in cca chromosomes homologous to human chromosomes or chromosome segments: pgd-eno1-pgm1, mdh1, idh1, pgm2, pgm3-me1, ak3, tpi-ldhb-pepb, gpi, and sod1. the following syntenic groups were observed but could not be localized: guk1-fh and mpi-pkm2. the following loci could not be localized with f ...19816951675
influence of cultural conditions on mitomycin c-mediated bacteriophage induction and release of salmonella toxin.several isolates of salmonella were examined for the capacity to synthesize and release a cholera toxin-like toxin that exerted a biological effect on chinese hamster ovary cells. measurements of this salmonella toxin, which was contained in cell sonic extracts and culture filtrates, were expressed in cholera toxin equivalents (nanograms), since the chinese hamster ovary cell responses of the cholera toxin and the salmonella toxin were indistinguishable. comparative titrations of salmonella prep ...19817012028
bisulfite (sulfur dioxide) is a comutagen in e. coli and in chinese hamster cells.the mutagenic and comutagenic effects of bisulfite were investigated. under moderate exposure conditions (high survival) it was found that bisulfite is not mutagenic to either eukaryotic cells (chinese hamster v79), or prokaryotic cells (escherichia coli). however, bisulfite does act as a comutagen with uv irradiation. bisulfite approximately doubles the mutation frequency in uv-irradiated chinese hamster v79 cells, and it causes a greater than 8-fold increase in trp+ revertants in uv-irradiated ...19817012605
influence of cell crowding on toxicity of nitroheterocycles.cell density (no. of cells per unit area or volume) during drug treatment may play a role of considerable importance in the interpretation of drug toxicity experiments performed in vitro. chinese hamster v-79 and mouse l-929 cells exposed to nitroheterocycles under aerobic conditions are considerably more sensitive to the cytotoxic effects of these drugs when incubated at low cell density (10(2) cells/cm2 or 10(4) cells/ml) than at higher cell density (10(4) cells/cm2 or 10(6) cells/ml). this ma ...19817013996
enterotoxigenic bacteria in food and water from an ethiopian community.food and water samples from an ethiopian community were screened for the presence of enterotoxin-producing bacteria. using the chinese hamster ovary cell assay, 40 of 213 isolates (18.8%) produced heat-labile (lt) enterotoxin. these lt-producing isolates comprised 33 of 177 (18.6%) strains from 24 of 68 food samples (35.3%) and 7 of 36 (19.4%) isolates of 4 of 17 water samples (23.5%). one lt-producing strain each of salmonella emek and of shigella dysenteriae was found. three pseudomonads, all ...19817016032
mutagenic evaluation of 1,1,2,3-tetrachloro-2-propene, a contaminant in pulp mill effluents, using a battery of in vitro mammalian and microbial tests.the mutagenicity of 1,1,2,3-tetrachloro-2-propene (tcp), a component of chlorinated pulp mill effluents, was investigated with a battery of in vitro mammalian and microbial assays. in fluctuation tests, tcp showed potent mutagenic activity with salmonella typhimurium strain ta1535 but only very weak activity with escherichia coli wp2. in chinese hamster ovary (cho) cells, tcp without metabolic activation induced chromosome aberrations. this activity was enhanced by the addition of aroclor 1254-i ...19817016270
the enucleation of cells on plastic leighton coverslips.a simple enucleation technique that facilitates autoradiographic and electron microscopic examination of cytoplasms is described. cells were grown on commercially available plastic leighton coverslips and these were centrifuged in the presence of cytochalasin b. the centrifugation requires no special holders and only a high speed centrifuge. enucleation frequencies of greater than 90% were obtained for chinese hamster fibroblasts and mouse b-82 cells.19817018026
mutagenicity of the bay-region diol-epoxides and other benzo-ring derivatives of dibenzo(a,h)pyrene and dibenzo(a,i)pyrene.the mutagenic activities of dibenzo(a,h)(pyrene, dibenzo(a,i)pyrene, and a total of 11 of their benzo-ring derivatives were evaluated in bacterial and mammalian cells in the absence or presence of a mammalian metabolic activation system. trans-1,2-dihydroxy-1,2-dihydrodibenzo(a,h)pyrene and trans-3,4-dihydroxy-3,4-dihydrodibenzo(a,i)pyrene, the expected dihydrodiol precursors of bay-region diol-epoxides, were metabolized to products which were more mutagenic to strains ta98 and ta100 of salmonel ...19817018665
the synthesis of ribosomal 5 s rna in cultured hamster cells during the inhibition of protein synthesis.ribosomal 5 s rna synthesis in chinese hamster v79 cells treated with an inhibitory antibiotic of protein synthesis, cycloheximide, was quantitated by hybridization of rna preparations with plasmid cole1-psc101 dna carrying xenopus 5 s dna. in v79 cells, cycloheximide produced a notable decrease in the production of the higher molecular weight ribosomal rna (rrna) fraction, whereas the accumulation of both 5 s rna and polyadenylate-containing messenger rna was much less affected. when the cellul ...19817020763
mutagenic activity of diallate and triallate determined by a battery of in vitro mammalian and microbial tests.diallate and triallate are carbamate herbicides used mainly for the pre-emergence control of wild oats in various crops. the genetic activity of these compounds was studied using a battery of microbial and mammalian in vitro tests. in the salmonella/mammalian-microsome assay, diallate and triallate show dose-related increases without metabolic activation in strains ta1535, ta100 and ta98, indicating that these compounds cause both frameshift and base-substitution mutations. mutagenicity of both ...19817022182
mutagenicity of nitrosated cimetidines.dinitrosocimetidine and mononitrosocimetidine were tested in a series of short term assay systems. both compounds were mutagenic in the absence of rat liver microsomes. the dinitrosocimetidine produced higher mutagenic or clastogenic effects at concentrations that were 50 to 500 times lower than the concentrations at which the mononitrosocimetidine produces its maximum effects. the most sensitive short term assay system was the chinese hamster ovary cell culture system. dinitrosocimetidine cause ...19817023725
detection of extracellular toxin(s) produced by vibrio vulnificus.conditions are described for the production, in high titers, a heat-labile, antigenic, extracellular toxin(s) by vibrio vulnificus, a recently recognized human pathogen. bacteriologically sterile culture filtrate preparations obtained from mid-logarithmic-phase cultures of the bacterium possessed cytolytic activity against mammalian erythrocytes, cytotoxic activity for chinese hamster ovary cells, vascular permeability factor activity in guinea pig skin, and lethal activity for mice. the specifi ...19817024134
radiation induced dna double strand breaks are rejoined by ligation and recombination processes.using the method of filter elution of double stranded dna under neutral conditions we have shown that most of gamma-ray induced double strand breaks (dsb) are rejoined in both mammalian and bacterial cells. rejoining also occurs in the g1 phase in v79 chinese hamster cells and under different growth conditions. within 8 minutes at 37 c, half the breaks are rejoined. the rejoining in e. coli is equally fast and depends on the presence of dna ligase. some of the breaks in e. coli rejoin slowly, an ...19817024911
metabolic activation and mutagenicity of 4 vinylic monomers (vinyl chloride, styrene, acrylonitrile, butadiene).the mutagenic activity and the metabolism of four vinylic monomers; vinyl chloride, styrene, acrylonitrile and butadiene are reviewed. those chemicals are converted by the mixed function oxidases system of the endoplasmic reticulum into reactive intermediates which can interact with macromolecules within the cell. in order to examine the mutagenic activity of these compounds and their metabolites, different mutagenicity testing systems have been used: tests with s. typhimurium, e. coli, schizosa ...19817025348
dna-mediated transfer of the mouse gene for hypoxanthine phosphoribosyltransferase into cultured mouse cells: no integration of the transferred gene at its homologous site in the host genome.an established chinese hamster cell line was fused with microcells isolated from phenotypically stable transferent mouse cells which contained a mouse transgenome coding for an abnormal form of mouse hypoxanthine phosphoribosyltransferase (hprt, ec. no. 2.4.2.8) (willecke et al. 1979). two hybrids were isolated which expressed the abnormal form of mouse hprt but no mouse alpha-galactosidase (gala, ec. no. 3.2.1.22). in one of these microcell hybrids the abnormal hprt activity segregated under co ...19816943409
characterization of the philadelphia chromosome by gene mapping.chinese hamster x human and mouse x human somatic cell hybrid lines were obtained using circulating leucocytes from six chronic myeloid leukemia patients. all six patients carried the ph1 translocation, t(9q+;22q-), characteristic of chronic myeloid leukemia, in their dividing immature granulocytes. analysis of independent hybrid clones yielded the following results: 1. the chromosome 9 markers, soluble aconitase and adenylate kinase-1, segregated with the 9q+ derivative. the latter marker has p ...19816944169
characterization of a complex philadelphia translocation (1p-;9q+;22q-) by gene mapping.human-chinese hamster somatic cell hybrids were obtained using circulating leucocytes from a chronic myeloid leukaemia (cml) patients carrying a complex philadelphia ((ph1) translocation (1p-;9q+;22q-). hybrid clones which showed segregation of the translocation chromosomes were studied. the chromosome 22 markers aco2, arsa, and naga segregated with the 1p- derivative; and the chromosome 1 markers umpk, pgd, and eno1 segregated with the 9q+ derivative. hence, molecular evidence has been obtained ...19816945288
highly conserved glucose-regulated protein in hamster and chicken cells: preliminary characterization of its cdna clone.a temperature-sensitive mutant k12 derived from a chinese hamster fibroblast has been shown to overproduce three specific proteins of mr 94,000, 78,000, and 58,000 when incubated at the nonpermissive temperature (40.5 degrees c). we previously identified these proteins as glucose-regulated proteins similar to those observed in chicken embryo fibroblasts when the cells are starved of glucose. in this report, we show that the mr 78,000 proteins isolated from the hamster k12 cell line and from chic ...19816946438
mouse alpha-globin genes and alpha-globin-like pseudogenes are not syntenic.a genetic polymorphism for a bgl i endonuclease site near the alpha-globin-like pseudogene alpha-4 of c57bl/6 and c3h/hen mice was used to show that alpha-4 was not affected by three independent mutations in which the adult globin genes alpha-1 and alpha-2 were deleted. these results indicated that alpha-4 might not be located adjacent to the adult alpha-globin genes on chromosome 11. restriction endonuclease analysis of dna of a primary clone of a chinese hamster--mouse somatic cell hybrid that ...19816947235
in vitro translation of hypoxanthine/guanine phosphoribosyltransferase mrna: characterization of a mouse neuroblastoma cell line that has elevated levels of hypoxanthine/guanine phosphoribosyltransferase protein.antibody specific for the native form of chinese hamster hypoxanthine/guanine phosphoribosyltransferase (hprt; imp:pyrophosphate phosphoribosyltransferase, ec 2.4.2.8) was used to detect the synthesis of hprt protein in a rabbit reticulocyte lysate translation system primed with mrna from chinese hamster tissues and cultured cells. electrophoretic analysis of the immunopurified products from the translation of mrna from wild-type and a series of mutant chinese hamster cells indicated that hprt s ...19816947270
decreased tumorigenicity of rodent cells after fusion with leukocytes from normal and leukemic donors.interspecific hybrid cells, derived from fusion of normal and leukemic (cml) human leukocytes with tumorigenic p19 mouse or a3 chinese hamster cells, were tested for their tumor-forming capacity in congenitally athymic nude mice. partial suppression of tumorigenicity was observed in several hybrid clones derived from both normal and leukemic leukocytes. chromosome analysis of the hybrid cells before inoculation in nude mice and of the derived tumors did not reveal a human chromosome bearing fact ...19816948415
reverse mutation tests in salmonella typhimurium and chromosomal aberration tests in mammalian cells in culture on fluorinated pyrimidine derivatives.reverse mutation (ames) tests with salmonella typhimurium ta98, ta100 and ta1537, and chromosomal aberration tests in vitro with a chinese hamster fibroblast cell line (chl), were carried out on fluorinated pyrimidine derivatives, such as 5-fluorouracil (5-fu), 1-(2-tetrahydrofuryl)-5-fluorouracil (ft), 5-fluorodeoxyuridine (fudr), 1,3-bis(2-tetrahydrofuryl)-5-fluorouracil (fd-1) and a mixture of uracil and ft in the molar ratio 4 : 1 (uft) (fujii et al., 1978). for comparison, similar tests wer ...19816454840
assignment of the human gene for liver-type 6-phosphofructokinase isozyme (pfkl) to chromosome 21 by using somatic cell hybrids and monoclonal anti-l antibody.human 6-phosphofructokinase (pfk; atp:d-fructose-6-phosphate 1-phosphotransferase, ec 2.7.1.11) is under the control of structural loci that code for muscle (m), liver (l), and platelet (p) subunits, which are variably expressed in different tissues; human diploid fibroblasts and leukocytes express all three genes. random tetramerization of these subunits produces various isozymes, which can be distinguished from one another by ion exchange chromatography or by subunit-specific monoclonal antibo ...19816455664
conservation of the syntenic group enol - pgd - pgm in mammals: its assignment to chromosome 2 in the chinese hamster.hybrids between cells from mouse permanent lines and chinese hamster thymus cells explanted from animals maintained mouse chromosomes and lost most hamster chromosomes. in twenty-seven hybrids examined for expression of enolase 1. phosphogluconate dehydrogenase, and phosphoglucomutase, the chinese hamster forms of the three enzymes were either expressed together, or not expressed at all. thus, the three genes eno1, pgd, and pgm appear syntenic in chinese hamster as they are in man (chromosome 1p ...19816456685
folylpoly-gamma-glutamate synthesis by bacteria and mammalian cells.the purification and properties of folylpolyglutamate synthetase from corynebacterium sp, and some properties of partially purified enzyme from lactobacillus casei, streptococcus faecalis, neurospora crassa, pig liver, and chinese hamster ovary cells, are described. the corynebacterium enzyme catalyzes a mgatp-dependent addition of glutamate to a variety of reduced pteroate and pteroylmono-, di-, and triglutamate substrates, with the concomitant production of mgadp and phosphate. although glutam ...19816458762
photodynamic effects of haematoporphyrin derivative on synchronized and asynchronous cells of different origin.phototherapy in the presence of haematoporphyrin derivative has been shown to have a preferential effect on malignant tumours when compared to normal tissue. this communication presents a comparison of the sensitivity to photochemotherapy in vitro of different cell lines. asynchronous populations of cells were exposed to light in the presence of haematoporphyrin derivative, and found to be inactivated with a comparable efficiency. the lines were of human, chinese-hamster or mouse origin and had ...19816459112
mutagenicity studies on alcohol extracts from gamma-irradiated potatoes.the alcohol extracts freshly prepared from gamma-irradiated potatoes were examined for their mutagenic activity in bacterial and mammalian cell systems. negative results were obtained from all following test systems: mutation assays with salmonella typhimurium his- strains such as ta 100, ta 98, ta 1535, ta 1537, and streptomycin-dependent mutant (smd) strain, ta 100-10, inductests with escherichia coli strains, k 12 gy 5027 and k 12 c600, chromosomal aberration tests with chinese hamster cells ...19817038779
stability of activating systems for in vitro mutagenesis assays: enzyme activity and activating ability following long-term storage at - 85 degrees c.activating systems for in vitro mutagenesis assays are commonly prepared and stored at low temperature until required. the objective of the studies reported here was to determine the long-term stability of activating systems stored at - 85 degrees c. a broad range of microsomal enzymes in the postmitochondrial supernatant (pms) and the microsomal fraction of livers from aroclor 1254 treated rats were studied in conjunction with the ability of these fractions to catalyse the conversion of dimethy ...19816786867
characterization of salmonella toxin released by mitomycin c-treated cells.the enzyme-linked immunosorbent assay and the chinese hamster ovary floating cell assay for cholera toxin have proven to be sensitive and reliable tests for determining the antigenic and biological characteristics of salmonella toxin, respectively. the addition of mitomycin c to the culture media 3 h after inoculation resulted in increased amounts of salmonella toxin in culture filtrates but had the reverse effect on cell sonic extracts. our data suggested that the increased amounts of salmonell ...19816788702
synthesis and antitumor activity of cysteinyl-3,4-dihydroxyphenylalanines and related compounds.the natural catecholic amino acid 5-s-cysteinyl-3,4-dihydroxyphenylalanine (1) was selectively toxic to a variety of human tumor cell lines in culture and exhibited antitumor activity against l1210 leukemia and b-16 melanoma in mice at doses which were not toxic to the host. structural analogues of 5-s-cysteinyl-3,4-dihydroxyphenylalanine including several new compounds, were synthesized and tested for growth inhibition of cultured cells of human neuroblastoma yt-nu and chinese hamster fibroblas ...19816788955
sheep gene mapping by somatic cell hybridization. iii. synteny between pyruvate kinase m2 (pkm2) and nucleoside phosphorylase (np) in domestic sheep.twenty-five independent chinese hamster x sheep hybrids were analysed for ovine pyruvate kinase m2 (pkm2), nucleoside phosphorylase (np) and mannosephosphate isomerase (mpi). an independent segregation is observed between pkm2 and mpi, whereas the results show a synteny between pkm2 and np.19816792977
swainsonine: an inhibitor of glycoprotein processing.swainsonine, an indolizidine alkaloid, inhibits the processing of asparagine-linked glycoproteins in both cell-free extracts and animal cells in culture. thus, in a liver particulate enzyme preparation, swainsonine at 0.1-1.0 microm inhibited the mannosidase that releases [3h]mannose from a high mannose glycopeptide but only slightly inhibited the release of glucose from a glucose-labeled glycopeptide. mdck and chinese hamster ovary cells in culture incorporate [2-3h]mannose and [6-3h]glucosamin ...19816801650
cloning of a functional gene responsible for the expression of a cell surface antigen correlated with human chronic lymphocytic leukemia.a cell--cell hybrid of a chinese hamster ovary (cho) cell line and human peripheral blood lymphoblasts from a patient with b-cell chronic lymphocytic leukemia produces a surface antigen detectable by a monoclonal antibody. this surface antigen can be detected at significant levels on a fraction of chronic lymphocytic leukemia cells, but not on normal human lymphocytes from peripheral blood or bone marrow. two different clones capable of transforming mouse cells to produce the surface antigen wer ...19816459855
inefficient internalization of receptor-bound low density lipoprotein in human carcinoma a-431 cells.human epithelioid carcinoma a-431 cells are known to express unusually large numbers of receptors for the polypeptide hormone epidermal growth factor. the current studies demonstrate that this cell line also expresses 5- to 10-fold more low density lipoprotein (ldl) receptors per cell than either human fibroblasts or chinese hamster ovary (cho) cells. as visualized with an ldl-ferritin conjugate, the ldl receptors in a-431 cells appeared in clusters that were distributed uniformly over the cell ...19816259181
rat bladder cell-mediated mutagenesis od chinese hamster v79 cells and metabolism of benzo[a]pyrene.primary rat bladder epithelial cells were cocultivated with chinese hamster v79 cells in the presence of carcinogens, and the induction of 6-thioguanine resistance in the v79 cells was used as a marker of cell-mediated mutagenesis. the carcinogens dimethylnitrosamine, 7,12-dimethylbenz[a]anthracene, and benzo[a]pyrene (bp) were mutagenic to v79 cells in the presence of bladder cells but not in their absence. analysis of bp metabolites formed by bladder cells indicated that 7,8-dihydro-7,8-dihydr ...19816262559
passage of an integral membrane protein, the vesicular stomatitis virus glycoprotein, through the golgi apparatus en route to the plasma membrane.the intracellular pathway of biogenesis of the vesicular stomatitis virus transmembrane glycoprotein was investigated in situ by using indirect immunofluorescence of whole infected chinese hamster ovary cells and immunoelectron microscopy of ultrathin frozen sections of infected cells. transport of the glycoprotein was synchronized by using the temperature-sensitive virus mutant orsay-45 and a temperature shift-down protocol. sequential appearance of the glycoprotein in the rough endoplasmic ret ...19816262824
titration of integrated simian virus 40 dna sequences, using highly radioactive, single-stranded dna probes.nick-translated simian virus 40 (sv40) [32p]dna fragments (greater than 2 x 10(8) cpm/micrograms) were resolved into early- and late-strand nucleic acid sequences by hybridization with asymmetric sv40 complementary rna. both single-stranded dna fractions contained less than 0.5% self-complementary sequences; both included [32p]-dna sequences that derived from all regions of the sv40 genome. in contrast to asymmetric sv40 complementary rna, both single-stranded [32p]dnas annealed to viral [3h]dna ...19816264104
cytopathogenicity of entamoeba histolytica: trophozoite homogenates modulate dna synthesis in a mammalian cell line.we examined the effect of total trophozoite homogenates from four axenized strains of entamoeba histolytica (hk9, hm1, hm2, and hm3) on the dna synthesis of subconfluent cultures of chinese hamster ovary (cho) cells incubated at low (0.1%) serum concentration. hm1, hm2, and hm3 extracts increased [3h]thymidine incorporation to acid-insoluble material in cho cells up to a maximum of 2.5, 1.5, and 1.5 times respectively, at doses of amebal protein ranging from 16 to 125 micron/ml. hm1 and hm2 extr ...19816264701
chromosome aberrations in chinese hamster embryonal fibroblasts after exposure to rous sarcoma virus. 19816266887
surface changes in cell membranes of chinese hamster embryo fibroblasts, normal and transformed by rous sarcoma virus, infected with influenza virus a2-texas. 19816266888
gonadotropin stimulation of pregnenolone metabolism in chinese hamster ovary cells in culture.to determine if chinese hamster ovary (cho) cells in culture are able to metabolize steroids, cho cells were incubated in defined medium with [14c]pregnenolone. as shown, [14c]pregnenolone is metabolized to progesterone and other delta 53 beta steroids; this steroidogenic response is appreciably enhanced upon exposure of the cells to 50 nm gonadotropins (human chorionic gonadotropin and follicle-stimulation hormone). the primary metabolites that accumulate in the medium upon treatment with gonad ...19816267080
sensitive determination of pyrimidine dimers in dna of uv-irradiated mammalian cells. introduction of t4 endonuclease v into frozen and thawed cells.endonuclease v from e. coli infected with phage t4 was used to evaluate the frequency and the removal of pyrimidine dimers from dna in cultured mammalian cells. cellular membranes were made permeable to the enzyme by two cycles of rapid freezing and thawing. the number of endonuclease-sensitive sites in dna was assayed by sedimentation in alkaline sucrose gradients upon which the cells were lysed directly. comparison of the frequency of endonuclease-sensitive sites with the frequency of pyrimidi ...19816267456
the mannose 6-phosphate receptor of chinese hamster ovary cells. compartmentalization of acid hydrolases in mutants with altered receptors.the localization of acid hydrolases was examined in chinese hamster ovary cells with defective mannose 6-phosphate receptors; these mutants had been shown to exhibit reduced uptake and altered binding of exogenously added acid hydrolase (robbins, a. r., myerowitz, r., youle, r. j., murray, g. j., and neville, d. m., jr. (1981) j. biol. chem. 256, 10618-10622). cells were grown in the presence of [3h]mannose, alpha-l-iduronidase and beta-hexosaminidase were immunoprecipitated sequentially, electr ...19816270123
characterization of a membrane-associated receptor from bovine liver that binds phosphomannosyl residues of bovine testicular beta-galactosidase.a receptor that binds the phosphomannosyl recognition marker of bovine testicular beta-galactosidase (beta-d-galactoside galactohydrolase, ec 3.2.1.23) was isolated from bovine liver membranes. the receptor was extracted from crude plasma membrane preparations with triton x-100 and immunoprecipitated as a receptor--beta-galactosidase complex with anti-beta-galactosidase. the receptor was dissociated from the precipitate with mannose 6-phosphate, labeled with 125i, and purified on a beta-galactos ...19816270668
requirement of the human chromosome 11 long arm for replication of herpes simplex virus type 1 in nonpermissive chinese hamster x human diploid fibroblast hybrids.somatic cell hybrids between chinese hamster (ch) lung cells (v79/380-6), nonpermissive for productive infection by herpes simplex type 1 (hsv-1), and permissive human diploid cells support productive hsv-1 infection as long as they retain human chromosome 11. human chromosome 3 has been reported to complement nonpermissivity in (ch) don cells (1). intraspecies hybrids between don/a3 and v79/380-6 cells, however, did not support hsv-1 replication, indicating lack of complementation. the block in ...19816270835
lung and liver cell-mediated mutagenesis systems: specificities in the activation of chemical carcinogens.a liver and lung cell-mediated-v79 cell mutagenesis system using intact cells as metabolic activation systems was employed to study the relative ability of cells from these organs to activate chemical carcinogens. primary cultures of liver and lung cells from male sprague dawley rats were used to metabolically activate the chemicals and the mutation of chinese hamster v79 cells to ouabain resistance used to detect mutagenic intermediates. 7,12-dimethylbenz[a]anthracene and 3-methylcholanthrene, ...19816271413
monoclonal antibodies to the low density lipoprotein receptor as probes for study of receptor-mediated endocytosis and the genetics of familial hypercholesterolemia.monoclonal antibodies directed against the low density lipoprotein (ldl) receptor have been prepared by immunization of mice with a partially purified receptor from bovine adrenal cortex. spleen cells from the mice were fused with the sp2/0-ag14 line of mouse myeloma cells. the most extensively studied monoclonal antibody, designated immunoglobulin-c7, reacts with the human and bovine ldl receptor, but not with receptors from the mouse, rat, chinese hamster, rabbit, or dog. 125i-labeled monoclon ...19816271765
role of adherence in cytopathogenic mechanisms of entamoeba histolytica. study with mammalian tissue culture cells and human erythrocytes.the enteric pathogen, entamoeba histolytica, appears to cause disease by adhering to and then destroying mucosal barriers. using an in vitro method of studying the interaction of e. histolytica with target cells (chinese hamster ovary [cho] and human erythrocytes [rbc]), we examined the mechanism of amebic adherence and its role in lysis of target cells. killing and phagocytosis of target cells by amebas ceases at 4 degrees c, allowing observation of adherence. amebas adhere to cho cells at 4 de ...19816271810
targeted killing of cultured cells by receptor-dependent photosensitization.this paper describes a method, designated "receptor-dependent photosensitization," by which the receptor-mediated endocytosis of low density lipoprotein (ldl) can be used to deliver a photosensitizing agent, pyrene, to cultured human and animal cells. the hydrophobic core of ldl is extracted and replaced with pyrene covalently coupled to cholesteryl oleate. this reconstituted ldl enters cells in significant amounts only when the cells express ldl receptors, resulting in the accumulation of pyren ...19816272315
methotrexate-resistant chinese hamster ovary cells have amplified a 135-kilobase-pair region that includes the dihydrofolate reductase gene.for the eventual purpose of isolating and studying a single animal cell replicon, we have developed a methotrexate-resistant chinese hamster ovary cell line that has amplified an early-replicating dna sequence approximately 500 times; this sequence includes the gene coding for dihydrofolate reductase (dhfr; tetrahydrofolate dehydrogenase; 5,6,7,8-tetrahydrofolate:nadp+ oxidoreductase, ec 1.5.1.3). dhfr composes 30% of the cytoplasmic protein in this cell line, and dhfr mrna represents 25% of the ...19816273843
carcinogen-mediated amplification of viral dna sequences in simian virus 40-transformed chinese hamster embryo cells.exposure of simian virus 40 (sv40)-transformed chinese hamster embryo cells to various chemical and physical carcinogens induced sv40 dna synthesis. although the carcinogen-mediated amplification of sv40 dna is regulated by the viral a gene, the induction of viral dna synthesis does not result in the rescue of infectious virus or the formation of complete viral dna molecules. instead, a heterogeneous collection of dna molecules containing sv40 sequences was generated by treatment with 7,12-dimet ...19816273853
morphologic study of the internalization of a lysosomal enzyme by the mannose 6-phosphate receptor in cultured chinese hamster ovary cells.the binding and internalization of a model lysosomal enzyme, beta-galactosidase, was visualized by use of rabbit anti-beta-galactosidase and goat anti-rabbit igg; the second antibody was labeled with rhodamine or fluorescein (for detection by fluorescence) or with horseradish peroxidase (for electron microscopy). chinese hamster ovary cells were incubated with beta-galactosidase at 4 degrees c, and then were washed and sequentially incubated in the cold with the two antibodies. the beta-galactos ...19816273898
the cloning and reintroduction into animal cells of a functional cad gene, a dominant amplifiable genetic marker.rodent cells resistant to pala, a specific inhibitor of the aspartate transcarbamylase activity of the multifunctional cad protein, overproduce cad as a result of amplification of the cad gene. we cloned a functional cad gene from syrian hamster cells using a cosmid vector. two independently isolated cosmids containing cad genes have inserts 40 and 45 kb long. we introduced the cloned genes into cad-deficient chinese hamster ovary (cho) cell mutants by fusing them with protoplasts of escherichia ...19816277500
chromosomes involved in production of infectious sv40 particles in mouse/sv40-transformed chinese hamster cell hybrids.the clone 6d hybrid, capable of expressing the virus-specific t-antigen but unable to produce infectious virus particles after superinfection, presented a complete mouse (3t3-4e) chromosome complement and a significant loss of chinese hamster (chk/svlp ag) chromosomes. similar properties were displayed by a budr-resistant derivative of the cl 6d hybrid (cl 6d.6bu). three independent superhybrid clones (cl 10b, cl 10c, cl 11a) isolated after backcross of the cl 6d.6bu hybrid with a nontransformed ...19816258123
temporal regulation of the rate of vesicular stomatitis virus mrna translation during infection of chinese hamster ovary cells. 19816258290
co-expression and amplification of dihydrofolate reductase cdna and the escherichia coli xgprt gene in chinese hamster ovary cells.we have transformed chinese hamster ovary cells with a plasmid containing mouse dihydrofolate reductase (dhfr) cdna and the escherichia coli xanthine-guanine phosphoribosyl transferase (xgprt) gene under the control of the mouse mammary tumor virus and sv40 early promoters, respectively. selection for the expression of xgprt using the dominant selection scheme described by mulligan and berg yields clones that simultaneously express dhfr. growth of these cells in progressively increasing concentr ...19816180118
immunochemical identification of the chick hprt gene transferred from chick erythrocytes to mammalian somatic cells.immunochemical methods were used to identify the genetic origin of hypoxanthine phosphoribosyltransferase (hprt) expressed in heteroploid, hprt-deficient mouse (a9) cells and chinese hamster ovary (k627) cells, after these cells were fused with chick embryo erythrocytes and selected for resistance to hypoxanthine-aminopterin-thymidine (hat) medium. all of the hat-selected clones produced hprt activity which was immunoprecipitable by an antiserum specific for chick hprt, but not by an antiserum s ...19816162618
quantitative analysis of intercellular adhesive specificity in freshly explanted and cultured cells.a new method is presented for the quantitative analysis of intercellular adhesive specificity. in this assay, two cell types are mixed, one unlabeled and the other labeled with the fluorescent dye, fluorescamine [4-phenylspiro(feran-2[3h],1'-phthalan)-3,3'-dione]. the resulting aggregates are analyzed by fluorescence microscopy to determine the number of labeled and unlabeled cells per aggregate. random (nonspecific) aggregation was characterized by a binomial distribution, and adhesive specific ...19816166626
karyotyping chromosomes by electron microscopy. condensation-inhibition of g bands in human and chinese hamster chromosomes by a brdu-hoechst 33258 treatment.a brdu-hoechst 33258 treatment of living cells, which selectively induced condensation-inhibition of g-band chromatin in human and chinese hamster chromosomes, is presented. as a consequence mitotic chromosomes showed high resolution r-banding patterns when examined by light and electron microscopy. besides each whole chromosome identification, this procedure also permitted the electron microscopic study of specific structures, such as satellites, secondary constrictions, telomeres, centromeres, ...19816169427
eliminating mycoplasmas from contaminated cell cultures.mycoplasmas are bothersome contaminants in cell cultures. cells derived from various sources are subject to contamination and although many procedures have been suggested to eliminate the contaminating mycoplasmas, there is no simple, rapid and effective method for eliminating them. we have devised a method for the selective killing of mycoplasmas based on the differences between the nucleic acid metabolism of mycoplasmas and that of tissue culture cells. whereas the nutritional requirements of ...19816169683
comparative genetics of hamster amylases.syrian (mesocricetus auratus) and chinese (cricetulus griseus) hamsters were phenotyped by electrophoresis for salivary and pancreatic amylases. syrian hamsters possess two salivary amylase electromorphs, the more anodal (fast) being invariant in 250 outbred and 17 representatives of 5 highly inbred lines. the slow electromorph had activity equal to that of the fast amylase (heavy), or had distinctly less activity (light), or was absent (null). the slow electromorph is inherited as an autosomal ...19816170291
purification and characterization of hypoxanthine-guanine phosphoribosyltransferase from saccharomyces cerevisiae.hypoxanthine-guanine phosphoribosyltransferase (hprt) was purified 12 000-fold to homogeneity from yeast by a three-step procedure including acid precipitation, anion-exchange chromatography, and guanosine 5' -monophosphate affinity chromatography. the enzyme is a dimer consisting of two, probably identical, subunits of mr 29 500. the enzyme recognized hypoxanthine and guanine, but not adenine or xanthine, as substrates. an antiserum against both native and denatured enzyme has been raised and s ...19816170313
effects of the l isomer (+)-1,2-bis(3,5-dioxopiperazine-1-yl)propane on cell survival and cell cycle progression of cultured mammalian cells.the effects of the l isomer (+)-1,2-bis(3,5-dioxopiperazine-1-yl)propane (icrf 159; nsc 169780) on cell viability, growth, and progression through the cell cycle were investigated in suspension cultures of murine leukemia (friend leukemia and l1210) cells and normal human lymphocytes stimulated with phytohemagglutinin and in adherent cultures derived from human neuroblastoma and chinese hamster ovary (cho) cells. cho cell colony formation was inhibited by 50% following either an 8.5-hr exposure ...19816171341
isolation of special antibodies which react only with homologous enterotoxins from vibrio cholerae and enterotoxigenic escherichia coli.cholera enterotoxin (ct) and heat-labile enterotoxin (lt) produced by enterotoxigenic escherichia coli share a common antigenic determinant. in addition, ct and lt each have a unique antigenic determinant. antisera were prepared by immunoaffinity chromatography against these unique antigenic determinants, that is, antiserum that reacted with ct but not with lt and antiserum that reacted with lt but not with ct. antiserum against the common antigenic determinant to ct and lt was also prepared by ...19816171516
an autoradiographic method of detecting a. laidlawii and m. hyorhinis in cell cultures.the autoradiographic investigation of l cells and chinese hamster cells for the presence of mycoplasmas (a. laidlawii and m. hyorhinis) using uridine/uracil (udr/u) testing is a rapid and reliable method suitable for the serial checking of even a small number of cells. it depends on a reduced incorporation of [3h]uridine and an increased uptake of [3h]uracil into the rna of mycoplasma-infected cells, shown in autoradiograms by the density of the grains and their distribution. results obtained by ...19816173306
glucocorticoid responsiveness of hepatoma cell hybrids.the dominance or recessiveness of glucocorticoid responsiveness and albumin production of different hepatoma cell lines were investigated using somatic cell hybrids. the majority of the intraspecific, intraorgan hybrids between glucocorticoid sensitive, tyrosine aminotransferase (tat) non-inducible, albumin non-secreting parents and glucocorticoid resistant, tat-inducible, albumin secreting parents were glucocorticoid sensitive, tat non-inducible and albumin non-producing. the tat inducibility w ...19816127852
role of asparaginase synthetase and asparagyl-transfer rna synthetase in the cell-killing activity of asparaginase in chinese hamster ovary cell mutants.the cell-killing activity of asparaginase on three classes of chinese hamster ovary cell mutants was examined: a mutant which overproduces asparagine synthetase (ah5); mutants defective in asparagine synthetase (n3 and n4); and mutants conditionally defective in asparagyl-transfer rna synthetase (asn 3, asn 7, and asn 9). the overproducer was more resistant to the cell-killing activity of asparaginase than wild-type chinese hamster ovary cells, while mutants defective in asparagine synthetase we ...19816113889
elevated levels of asparagine synthetase activity in physiologically and genetically derepressed chinese hamster ovary cells are due to increased rates of enzyme synthesis.the activity of asparagine synthetase in chinese hamster ovary (cho) cells is increased in response to asparagine deprivation or decreased aminoacylation of several trnas (andrulis, i. l., hatfield, g. w., and arfin, s. m. (1979) j. biol. chem. 254, 10629-10633). cho cells resistant to beta-aspartylhydroxamate have up to 5-fold higher levels of asparagine synthetase than the parental line (gantt, j. s., chiang, c. s., hatfield, g. w., and arfin, s. m. (1980) j. biol. chem. 255, 4808-4813). we ha ...19816114097
regulation of proline biosynthesis: the inhibition of pyrroline-5-carboxylate synthase activity by ornithine.mammalian cells have the capacity for proline biosynthesis from ornithine or glutamic acid. using a radioisotopic assay, we have studied the regulation by ornithine of delta 1-pyrroline-5-carboxylate synthase, the enzyme that catalyzes the first step of proline biosynthesis from glutamic acid. in homogenates from chinese hamster ovary cells, ornithine was found to be a potent inhibitor of pyrroline-5-carboxylate synthase activity(50% inhibition at 0.37 mm). the effect was reversible and did not ...19816115302
a simple assay to detect escherichia coli producing heat labile enterotoxin: results of a field study of the biken tests in bangladesh.in the biken test a precipitin line forms in the agar between an escherichia coli colony producing heat-labile enterotoxin (lt) and anti-cholera-toxin or anti-lt sera placed in an adjacent well. e. coli isolates form 273 unselected patients with diarrhoea and 516 stock cultures of known toxin type were screened blindly for lt production by means of the biken tests and the standard chinese hamster ovary (cho) cell assay. the biken tests was 98% sensitive and 99% specific. all results of the biken ...19816116087
distinct high-affinity binding sites for benzomorphan drugs and enkephalin in a neuroblastoma--brain hybrid cell line.the high-affinity binding of benzomorphan drugs (ethylketocyclazocine and n-allylnorcyclazocine) and [dala2,dleu5] enkephalin was examined in a mouse neuroblastoma--chinese hamster brain clonal hybrid cell line (ncb-20). scatchard analysis of saturation binding isotherms indicated the presence of a single binding site for 3h-labeled [dala2,dleu5]enkephalin (kd = 3 nm) and multiple binding sites for [3h]ethylketocyclazocine (kd = 4 and 20 nm) and n-[3h]allylnorcyclazocine (kd = 0.5 and 15 nm). bo ...19816117074
isolation of a taxol-resistant chinese hamster ovary cell mutant that has an alteration in alpha-tubulin.taxol is a plant alkaloid that has antimitotic activity and appears to stabilize microtubules [schiff, p. b., fant, j. & horwitz, s. b. (1979) nature (london) 277, 665-667]. taxol-resistant cells were selected from a population of uv-mutagen-treated chinese hamster ovary cells by a single-step procedure. these mutants have normal morphologies and growth rates but are 2- to 3-fold more resistant to the toxic effects of the drug than the wild-type parent. one out of 20 mutants screened by two-dime ...19816117076
conserved autosomal syntenic group on mouse (mmu) chromosome 15 and human (hsa) chromosome 22: assignment of a gene for arylsulfatase a to mmu 15 and regional mapping of dia1, arsa, and aco2 on hsa 22.we have utilized a panel of chinese hamster x mouse somatic cell hybrids segregating mouse chromosomes to assign a gene for arylsulfatase a (arsa) to mouse chromosome 15. considering our previous assignment of a gene for diaphorase-1 (dia1) to the same mouse chromosome, we have evidence for another syntenic relationship that has been conserved, since the homologous loci for human arsa and dia1 are both located on human chromosome 22. because mmu 15 and hsa 22 are quite dissimilar in size and ban ...19816118238
assignment of adenosine deaminase complexing protein (adcp) gene(s) to human chromosome 2 in rodent-human somatic cell hybrids.the experiments reported in this paper indicate that the expression of human adenosine deaminase complexing protein (adcp) in the human-rodent somatic cell hybrids is influenced by the state of confluency of the cells and the background rodent genome. thus, the complement of the l-cell derived a9 or b82 mouse parent apparently prevents the expression of human adcp in the interspecific somatic cell hybrids. in the a3, e36, or rag hybrids the human adcp expression was not prevented by the rodent g ...19816120891
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