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
transfer of the human genes coding for thymidine kinase and galactokinase to chinese hamster cells and human-chinese hamster cell hybrids.cotransfer of two linked human genes, coding for the enzymes thymidine kinase (tk) and galactokinase (gak) was demonstrated following incubation of chinese hamster tk-deficient cells with isolated human chromosomes. the 5 colonies which were isolated all expressed a stable tk-positive phenotype. cotransfer of the human genes coding for tk and gak has also been observed in experiments in which isolated human chromosomes were incubated with tk-deficient human-chinese hamster cell hybrids. these re ...1977204067
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
direct fluorescent assay of urokinase and plasminogen activators of normal and malignant cells: kinetics and inhibitor profiles.a direct rate assay for plasminogen activator has been developed using a synthetic fluorogenic peptide substrate, 7-(n-cbz-glycylglycylargininamido)-4-methylcoumarin trifluoroacetate. the assay correlates well with the standard 125i-labeled fibrin plate assay using highly purified urokinase, culture fluids from wi-38, chinese hamster vary or hela cells, or rous sarcoma virus-transformed chick fibroblasts as the source of plasminogen activator. the assay is sensitive, rapid, and linear throughout ...1978204931
cotransfer of thymidine kinase and galactokinase genes by chromosome-mediated gene transfer.the chinese hamster genes for thymidine kinase (atp:thymidine 5'-phosphotransferase, ec and galactokinase (atp:d-galactose 1-phosphotransferase, ec 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
mutagenesis of chinese hamster cells in vitro by combination treatments with methyl methanesulfonate and n-acetoxy-2-acetylaminofluorene.mutational synergism was examined in chinese hamster v79 cells exposed to methyl methanesulfonate followed by n-acetoxy-2-acetylaminofluorene (acaaf) at different time intervals. treatment with 500 micron methyl methanesulfonate resulted in 95% survival of cloning ability and induced approximately 4 azaguanine-resistant mutants/10(5) survivors. seven micron acaaf produced 10 times as many mutants, and the survival was 7%. lethal synergism was observed for methyl methanesulfonate treatments follo ...1978208770
localization of the binding site for cell attachment in the alpha1(i) chain of collagen.certain cells such as cho (chinese hamster ovary) and fibroblasts attach to a substrate of type i collagen via proteins that link the cell surface to collagen. serum contains a glycoprotein, c-cap (collagen cell attachment protein), that can mediate this adhesion. previously, we established that alpha1(i)-cb7 (cyanogen bromide peptide 7), which lies within residues 552 to 822 of collagen, contains a major binding site for c-cap(alpha1(i)-cb7 has been renumbered to account for an additional tripl ...1978209046
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 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, mckusick no. 17245), 6-phosphogluconate dehydrogenase [pgd; ec, 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. deficient chinese hamster cells with alpha-galactosidase a (e.c. deficient cells from a patient with fabry's disease yielded hybrids which contained both human and hamster hprt, g6pd (e.c., and aprt (e.c. 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
shedding of the glycoprotein from vesicular stomatitis virus-infected a culture of chinese hamster ovary cells infected with vesicular stomatitis virus, there is specific shedding of viral antigens into the medium. this shedding appears to be unrelated to progeny formation or to cell lysis. although all five of the virus-specific proteins are detected in the extracellular soluble fraction, the major antigen is the gs protein. this protein has a molecular weight of 54,000. indirect analysis of the content of sialic acid as well as peptide analysis of the gs and ...1978211264
assignment of the receptor for ecotropic murine leukemia virus to mouse chromosome 5.the gene for the receptor for ecotropic murine leukemia virus (rev) has been assigned to mouse chromosome 5. this determination was made possible by an analysis of somatic cell hybrids between mouse and chinese hamster cells. the parents of these hybrids were a/hej or mus poschiavinus peritoneal exudate cells or balb/c primary embryo fibroblasts and e36, a chinese hamster lung fibroblast deficient in hypoxanthine guanine phosphoribosyltransferase. segregation of mouse chromosomes in these hybrid ...1978212501
cytogenetic studies of a simian virus 40 temperature-sensitive mutant-transformed chinese hamster cell clone at the permissive and nonpermissive temperature.a clone of chinese hamster embryo cells transformed by tsa58, the temperature-sensitive mutant of simian virus 40, was analyzed for chromosome abnormalities at the permissive temperature (37 degrees c) and nonpermissive temperature (40.5 degrees c). trypsin-giemsa-banded metaphases were analyzed 1 week after the temperature shift. the metaphases from cells at both temperatures were pseudodiploid, with numerous chromosome changes primarily affecting chromosomes no. 1 and 2. other chromosomes (no. ...1978212571
simian virus 40 a gene function: dna content analysis of chinese hamster cells transformed by an early temperature-sensitive virus mutant.replication of two chinese hamster embryo cell lines transformed by an early temperature-sensitive mutant of simian virus 40, tsa58, was examined by flow microfluorometry and autoradiography of [3h]thymidine-labeled cells in order to determine whether transformed cell dna synthesis is initiated by the virus a gene. at the permissive temperature (37 degrees), cells transformed by the mutant were like the wild-type virus transformants in appearance, colony-forming ability, high saturation density, ...1978212747
a herpes simplex virus 1 integration site in the mouse genome defined by somatic cell genetic analysis.transfection experiments with hsv 1 in which one uses herpes simplex virus (hsv) thymidine kinase (tk) as a selectable prototrophic marker yield two classes of transformed cells: stable and unstable. in this report, we test the hypothesis that the stability phenotype can be explained by virus genome integration into a recipient cell chromosome. the method of analysis is by means of somatic cell genetics. we have isolated a series of microcell hybrids between a tk- chinese hamster cell line and a ...1978214240
localization of a gene for human alpha-galactosidase b (= n-acetyl-alpha-d-galactosaminidase) on chromosome 22.the localization of the structural gene for human alpha-galactosidase b (= n-acetyl-alpha-galactosaminidase) was investigated by means of man-chinese hamster and man-mouse somatic cell hybrids. the hybrid clones were analyzed for chromosomes and for a large number of known enzyme markers. the lysates of the hybrid cells were treated with sepharose-coupled antihuman alpha-galactosidase b and the activity of the adsorbed enzyme was measured on the sepharose beads as n-acetyl-alpha-galactosaminidas ...1978215508
lipid-saccharide intermediates and glycoprotein biosynthesis in a temperature-sensitive chinese hamster cell mutant.the characterization of a temperature-sensitive chinese hamster cell mutant has been continued with the aim of localizing the apparent defect in glycoprotein synthesis (tenner et al., '77). although the mutation is lethal, a demonstration of the ability of the mutant cells to support proliferation of mengo virus at the nonpermissive temperature indicates that the general metabolic processes of the cells remain intact at a time when glycoprotein synthesis is severely depressed. a quantitative stu ...1979217883
study on the mutagenicity of conjugated estrogens in human, animal and bacterial systems.conjugated estrogens were studied for mutagenicity (and implied carcinogenicity) in two strains of s. typhimurium, two normal and three neoplastic human lymphoid cell lines (the latter from burkitt's lymphoma patients) in cell culture and a chinese hamster cell line in diffusion chambers implanted into mice. no significant increase in mutation rate or chromosome aberrations were noticed after exposure to conjugated estrogens.1978217940
binding site on macrophages that mediates uptake and degradation of acetylated low density lipoprotein, producing massive cholesterol deposition.resident mouse peritoneal macrophages were shown to take up and degrade acetylated (125)i-labeled low density lipoprotein ((125)i-acetyl-ldl) in vitro at rates that were 20-fold greater than those for the uptake and degradation of (125)i-ldl. the uptake of (125)i-acetyl-ldl and its subsequent degradation in lysosomes were attributable to a high-affinity, trypsin-sensitive, surface binding site that recognized acetyl-ldl but not native ldl. when (125)i-acetyl-ldl was bound to this site at 4 degre ...1979218198
regional localization of the gene for human phosphoribosylpyrophosphate synthetase on the x chromosome.sixty-eight independent hybrid clones were isolated after irradiated normal human lymphocytes were fused with chinese hamster fibroblasts lacking hypoxanthine-guanine phosphoribosyltransferase activity. the cells were grown under selective conditions requiring retention of the x chromosome-linked locus for human hypoxanthine-guanine phosphoribosyltransferase. the frequency and patterns of cotransference of human phosphoribosylpyrophosphate synthetase with the selected marker and with additional ...1979218284
biosynthesis of lipid-linked oligosaccharides. isolation and structure of a second lipid-linked oligosaccharide in chinese hamster ovary cells.previous work has shown that vesicular stomatitis virus-infected chinese hamster ovary cells contain a major high molecular weight lipid-linked oligosaccharide which is transferred en bloc to protein during the formation of the asparagine-linked complex-type oligosaccharides of the vesicular stomatitis virus g protein (tabas, i., schlesinger, s., and kornfeld, s. (1978) j. biol. chem. 253, 716-722). we now report the characterization of a second, lower molecular weight lipid-linked oligosacchari ...1979218953
genes controlling receptors for ecotropic and xenotropic type c virus in mus cervicolor and mus musculus.gene loci controlling cell surface receptors for murine leukemia virus were studied by using murine x chinese hamster hybrid cells. hybrids which exclusively segregate murine chromosomes were made by fusing mus cervicolor and mus musculus lymphocytes to hamster fibroblasts. sensitivity to moloney murine leukemia virus infecotion and specific binding of the envelope glycoprotein of rauscher murine leukemia virus (gp70) cosegregate and isozyme analysis show an association with chromosome 5 in both ...1979219245
phosphorylation of t-antigen and control t-antigen expression in cells transformed by wild-type and tsa mutants of simian virus 40.chinese hamster lung (chl) cells transformed by wild-type simian virus 40 (cell line chlwt15) or transformed by the simian virus 40 mutants tsa30 (cell lines chla30l1 and chla30l2) or tsa239 (cell line chla239l1) were used to determine the rates of turnover and synthesis of the t-antigen protein and the rate of turnover of the phosphate group(s) attached to the t-antigen at both the permissive and restrictive temperatures. the phosphate group turned over several times within the lifetime of the ...1979219256
regional asssignments of the loci ak3, acons, and ass on human chromosome 9.experiments are described in which human cells carrying balanced reciprocal translocations involving four different regions of chromosome 9 were fused with a chinese hamster cell line and the resulting hybrids used to obtain subchromosomal assignments of the loci ass, ak3, and acons. ass was localized on the distal portion of the long arm of chromosome 9, in the region 9q34 leads to 9qter, and ak3 and acons on the short arm, in the region 9pter leads to 9p13.1979219990
coordinate overproduction of orotate phosphoribosyltransferase and orotidine-5'-phosphate decarboxylase in hamster cells resistant to pyrazofurin and 6-azauridine.cells resistant to pyrazofurin and 6-azauridine have been selected from a simian virus 40-transformed syrian hamster line and from a chinese hamster lung line. by increasing the concentrations of inhibitors in several steps, mutant cells from both lines have been obtained which resist high concentrations (1 to 5 mm) of the two inhibitors separately or together. orotidine-5'-phosphate decarboxylase (ec, the sixth and last enzyme in ump biosynthesis, is inhibited by the nucleoside monoph ...1979220255
karyology and tumorigenicity of a simian virus 40-transformed chinese hamster cell clone.a pseudodiploid clone of chinese hamster cells tranformed in vitro with simian virus 40 (sv40) was isolated from soft agar and injected into nude mice through three successive passages with a short in vitro cultivation between each animal inoculation. the original clone and the three subsequent tumor populations were characterized in regard to sv40 t antigen staining, modal chromosome number, and giemsa-banded karyotype. all tumor cell lines maintained the pseudodiploid mode, as well as the posi ...1979220269
gonadotropin stimulation of cyclic amp levels in chinese hamster ovary cells in culture.when chinese hamster ovary (cho) cells, incubated in serum-free medium, are exposed to gonadotropins a transient increase in the intracellular concentration of cyclic amp is observed. maximum accumulation of cyclic amp is noted 30 minutes after addition of either human chorionic gonadotropin (hcg) or follicle stimulating hormone (fsh). within one to two hours after hormone addition, the intracellular concentrations of cyclic amp have returned to basal levels. the enhancement of intracellular cyc ...1979222777
the roles of the simian virus 40 tumor antigens in transformation of chinese hamster lung cells.simian virus 40 mutants and deletions between 0.54 and 0.59 map units direct the synthesis of defective 20k t antigens (crawford et al., 1978). these deletion mutants transformed actively growing chl cells nearly as efficently as did wild-type virus, in either the focus formation assay or the growth in soft agar assay. in contrast, when chl cells were in a resting state during infection, the transformation frequency of the mutants relative to wild-type dropped approximately 50 fold. the presence ...1979225037
extension of branching processes from hybrids of brain and chinese hamster ovary cells. 1979225185
loss of epidermal growth factor requirement and malignant transformation.serum provides growth factors that regulate and limit the growth of normal cells in tissue culture. animal cells that are malignantly transformed usually exhibit diminished serum requirements for growth in culture. we have used a defined, serum-free medium to determine which of these growth factors becomes dispensable for the growth of transformed syrian and chinese hamster fibroblast cells. the medium's four growth factors-epidermal growth factor (egf), insulin, fibroblast growth factor, and tr ...1979226990
escherichia coli heat-labile enterotoxin: dna-directed in vitro synthesis and structure.escherichia coli heat-labile enterotoxin was synthesized in a cell-free system directed by dna of the plasmid p307. synthesis of the toxin, assayed by the elongation induced in chinese hamster ovary cells, was strongly stimulated by cyclic amp and occurred at physiological levels of mg2+ only when the polyamine spermidine was present. activity was abolished by heat and antisera prepared against the enterotoxins of both e. coli p263 and vibrio cholera. tritium-labeled enterotoxin was purified by ...1979228267
roles of the simian virus 40 tumor antigens in transformation of chinese hamster lung cells: studies with simian virus 40 double mutants.simian virus 40 mutants containing both a tsa mutation (rendering the 90,000 molecular weight [90k] t-antigen thermolabile) and a deletion between 0.54 and 0.59 map units (reducing the size and the amount of the 20k t-antigen) were used to transform chinese hamster lung cells. the frequencies of transformation by the double mutants were comparable to that of the tsa mutant alone by both the focus and agar assays except when the cells were serum depleted before infection. growth-arrested cells we ...1979229242
enhancement of oxygen toxicity by diethyldithiocarbamate on chinese hamster and mouse cells. 1979231599
expression of galactose-1-p-uridyltransferase in chinese hamster x human galactosemia somatic cell hybrids.lymphocytes from a patient with classic galactosemia (galt deficiency) were hybridized with a chinese hamster cell line. electrophoretic valuation of galt in 31 independently derived interspecific hybrid clones failed to demonstrate expression of the human galt gene even when human chromosome 9 was present. possible mechanisms for this lack of expression are presented.1979231967
quantitative electron microscopy of intracytoplasmic type a particles at kinetochores of metaphase chromosomes isolated from chinese hamster and murine cell lines.we have successfully isolated and spread individual chromosomes of cho-ki cells for electron microscopic karyotyping. controlled preparation permitted a quantitative evaluation of the association between endogenous intracytoplasmic type a virus precursor particles and the centromeric region (kinetochores) of isolated chromosomes at prophase and metaphase. our results suggest the transfer of type a particles from the cytoplasmic to the centromeric regions during early metaphase in conjunction wit ...1979232135
expression of simian virus 40 gene a affects tubulin stability.the stability of tubulins present in crude extracts of untransformed balb/c-3t3 mouse fibroblasts, chinese hamster lung cells, and various of their simian virus 40 transformants was assessed by measurement of their individual colchicine-binding decay rates. in all cases studied the decays followed the kinetics of first-order reactions, and rates were reduced at low temperatures and by vinblastine sulfate. under all assay conditions, including different temperatures and protein concentrations, t ...1979232186
in vitro transformation of primary chinese hamster cells by minichromosomes from simian virus 40.purified sv 40 dna and sv 40 minichromosomes, either isolated from sv 40 infected cells (nami) or reconstituted from viral dna and the h1 depleted calf thymus histone fraction (remi), were tested for their ability to transform primary chinese hamster lung (chl) cells. using the agar suspension technique as the transformation assay, an approximately 200 fold increase in transformation activity for nami in comparison with the sv 40 dna and an approximately 50 fold increased activity in comparison ...1979232409
increased mutation rates in doubly viral transformed chinese hamster untransformed parental chinese hamster cell line, one polyoma transformed clone, and two clones containing both sv40 and polyoma dna were tested for the appearance of variants resistant to 6-thioguanine or oubain. the frequency of such variants was found to be highest in doubly transformed cells. the mutation rate at these loci was correlated with the level of transformation. the mutants observed were stable and had low reversion frequencies with no gross cytogenetic changes. these results es ...1979232576
effects of asbestos on epithelioid cell lines.the in vitro effects of asbestos fibers on the growth and viability of cho cells, an epithelioid cell line derived from chinese hamster ovary, and on k-22 cells, an epithelial cell line derived from rat liver, have been studied. relatively low concentrations of asbestos (10 micrograms/ml) were quite cytotoxic to both cell types. a sample of chrysotile asbestos was more toxic than samples of crocidolite or amosite. the toxic factor could not be extracted from the asbestos and toxicity occurred on ...1978233816
immunochemical evidence for glutamine-mediated degradation of glutamine synthetase in cultured chinese hamster cells.the specific activity of glutamine synthetase in cultured chinese hamster cells is inversely related to the concentration of glutamine in the surrounding solution. enzyme specific activity increases 8- to 10-fold when glutamine is removed from serum-free f12 growth media. the induction of glutamine synthetase activity occurs only after glutamine removal and not after the removal of other amino acids (methionine, leucine, or isoleucine). the analysis of the glutamine-mediated decrease in glutamin ...1975234454
human gene mapping and cancer biology.the topics covered in this paper include: (i) a somatic cell genetics approach for measuring the individual variability in the susceptibility to dna damage/repair at the level of specific chromosomal sites; (ii) a rationale for a selective chemotherapy and/or immunotherapy of chromosomally unbalanced tumours; and (iii) studies on complementation for sister chromatid exchange (sce) in roden-human hybrids. preliminary studies indicate that the 'radiation co-transfer method' for gene mapping can be ...1979258171
microcell-mediated transfer of murine chromosomes into mouse, chinese hamster, and human somatic this report, we describe the production and characterization of proliferating hybrid cell populations generated by fusion of murine microcells with intact mouse, chinese hamster, and human recipient cells. the microcell hybrids so produced contained one to five intact murine chromosomes derived from the microcell donor. these transferred chromosomes were maintained as functioning genetic elements in the hybrid cells. our results firmly establish subnuclear particle-mediated chromosome transfe ...1977264685
assignment of the major histocompatibility complex to a region of the short arm of human chromosome 6.interspecific cell hybrids containing defined parts of human chromosome 6 were used for regional mapping of gene loci previously assigned to chromosome 6: the human leukocyte antigens (hla) region, phosphoglucomutase-3 (pgm3; alpha-d-glucose-1,6-bisphosphate:alpha-d-glucose-1-phosphate phosphotransferase, ec and malic enzyme-1 [malic dehydrogenase(decarboxylating) (nadp+), l-malate:nadp+ oxidoreductase (oxaloacetate-decarboxylating), ec]. human fibroblasts containing a balanced ...1977265561
serial transfer of a human gene to rodent cells by sequential chromosome-mediated gene transfer.the human hypoxanthine phosphoribosyl-transferase (imp:pyrophosphate phosphoribosyltransferase, ec gene (hprt) has been serially transferred to mouse cells and then to chinese hamster fibroblasts by two cycles of metaphase chromosome isolation and incubation with recipient cells. human metaphase chromosomes were incubated with mouse a9 cells deficient in hypoxanthine phosphoribosyltransferase, and independent colonies expressing the human species form of this gene were isolated in a sel ...1977268645
stable association of the human transgenome and host murine chromosomes demonstrated with trispecific microcell hybrids.trispecific microcell hybrids were prepared by transferring limited numbers of chromosomes from a human/mouse gene-transfer cell line to a chinese hamster recipient line. the donor cells employed were murine l-cells that stably expressed the human form of the enzyme hypoxanthine phosphoribosyltransferase. karyotypic, zymographic, and back-selection tests of the resulting human/mouse/chinese hamster microcell hybrids provided strong genetic evidence for a stable association of the human transgeno ...1977269444
assignment of the human gene for galactose-1-phosphate uridyltransferase to chromosome 9: studies with chinese hamster-human somatic cell hybrids.chinese hamster-human somatic cell hybrids were analyzed for the expression of human galactose-1-phosphate uridyltransferase (galt; udpglucose:alpha-d-galactose-1-phosphate uridyltransferase, ec by electrophoresis and for the presence of human chromosomes cytogenetically with the aid of q-banding. three of the 10 randomly chosen independently derived primary hybrid lines showed the presence of human galt. human chromosome 9 was consistently present in the hybrid lines expressing human ...1977271990
diphtheria toxin has the properties of a lectin.the inhibition of protein synthesis in chinese hamster v79 cells by diphtheria toxin is antagonized by the lectins concanavalin a, succinylated concanavalin a, and wheat germ agglutinin but not by proteus vulgaris phytohemagglutinin or abrus agglutinin. the effects of concanavalin a and wheat germ agglutinin are reversed by methyl alpha-mannoside and n-acetylglucosamine, respectively. the inhibition of diphtheria toxin as a function of concanavalin a concentration fits a model of competitive inh ...1978272642
tumorigenicity and its suppression in cybrids of mouse and chinese hamster cell lines.the effect of cytoplasm upon the expression of tumorigenicity was examined with a pair of mouse and a pair of chinese hamster cell lines, in intraspecies cybrids formed by reciprocal fusions between either tumorigenic or nontumorigenic cells and cytoplasms derived from them. with the mouse cells, 3t3 and the simian virus 40-transformed line svt2, the cybrid clones were tumorigenic when svt2 cells were fused with 3t3 cytoplasts, but not in the reciprocal fusion. with the hamster cells, chef/18 an ...1978276880
chimeric toxins: toxic, disulfide-linked conjugate of concanavalin a with fragment a from diphtheria toxin.a disulfide-linked conjugate of concanavalin a (con a) and fragment a from diphtheria toxin has been synthesized and shown to be toxic for hela (human), chinese hamster ovary (cho), and sv3t3 (murine) cells. the conjugate was constructed by first coupling cystamine to con a with a carbodiimide reagent and then reacting the modified con a with reduced fragment a under conditions promoting disulfide interchange. the desired conjugate, obtained in nearly 50% yield relative to input of fragment a, w ...1978281682
inducers of dna synthesis present during mitosis of mammalian cells lacking g1 and g2 phases.the cell cycle analysis of chinese hamster lung fibroblast v79-8 line by the premature chromosome condensation method has confirmed the absence of measurable g1 and g2 periods. sendai virus-mediated fusion of mitotic v79-8 cells with g1 phase hela cells resulted in the induction of both dna synthesis and premature chromosome condensation in the latter, indicating the presence of the inducers of dna synthesis above the critical level not only throughout s phase, as it is in hela, but also during ...1978283413
measurement of mutagenesis in mammalian cells.a method using mammalian cells in vitro for detection and quantitation of mutagenic actions that appears to be useful for screening for carcinogenesis and genetic damage by environmental agents is presented. the method involves use of stable human--chinese hamster ovary hybrid cells that have retained a single human chromosome not necessary for cell reproduction. forward mutations are detected in genes necessary for production of specific human cell surface antigens. such mutants form colonies i ...1979286318
dna-mediated transfer of the adenine phosphoribosyltransferase locus into mammalian this report, we demonstrate the feasibility of transforming mouse cells deficient in adenine phosphoribosyltransferase (aprt; amp:pyrophosphate phosphoribosyltransferase, ec to the aprt+ phenotype by means of dna-mediated gene transfer. transformation was effected by using unfractionated high molecular weight genomic dna from chinese hamster, human, and mouse cells and restriction endonuclease-digested dna from rabbit liver. the transformation frequency observed was between 1 and 10 ...1979286319
isolation of lysosomal alpha-mannosidase mutants of chinese hamster ovary cells.a method is presented for detection of lysosomal hydrolase activity in situ in colonies of chinese hamster ovary cells. this method was used to screen for mutants deficient in lysosomal alpha-mannosidase. mutagenized cells were replicated onto filter papers [esko, j. d. & raetz, c. r. h. (1978) proc. natl. acad. sci. usa 75, 1190-1193] and allowed to divide for 11-14 days; cells on the filter replicas were lysed, and the filters were incubated with 4-methylumbelliferyl-alpha-d-mannopyranoside at ...1979287030
germ line integration of moloney leukemia virus: identification of the chromosomal integration site.the chromosomal integration site of the structural gene of moloney murine leukemia virus (m-mulv) in the genome of balb/mo mice was mapped genetically. these mice transmit the exogenous m-mulv as an endogenous virus at a single mendelian locus. two independent experimental approaches were used: (i) non-virus-producing fibroblasts prepared from homozygous balb/mo embryos were fused to chinese hamster wg3-h-o cells. in an analysis of 30 independent mouse-chinese hamster cell hybrid clones, the seg ...1979287034
assignment of the gene for cytoplasmic superoxide dismutase (sod-1) to a region of chromosome 16 and of hprt to a region of the x chromosome in the the search for homologous chromosome regions in man and mouse, the locus for cytoplasmic superoxide dismutase (sod-1; superoxide:superoxide oxidoreductase, ec is of particular interest. in man, the sod-1 gene occupies the same subregion of chromosome 21 that causes down syndrome when present in triplicate. although not obviously implicated in the pathogenesis, sod-1 is considered to be a biochemical marker for this aneuploid condition. using a set of 29 mouse-chinese hamster somatic ...1979291939
regional localization of human gene loci on chromosome 9: studies of somatic cell hybrids containing human translocations.somatic cell hybrids were derived from the fusion of (1) chinese hamster cells deficient in hypoxanthine guanine phosphoribosyltransferase (hprt) and human cells carrying an x/9 translocation and (2) chinese hamster cells deficient in thymidine kinase (tk) and human cells carrying a 17/9 translocation. several independent primary hybrid clones from these two series of cell hybrids were analyzed cytogenitically for human chromosome content and electrophoretically for the expression of human marke ...1979292306
resistance against cycloheximide in cell lines from chinese hamster and human cells is conferred by the large subunit of cytoplasmic ribosomes.cell lines from chinese hamster ovary [cho-k1-d3] and human fibroblast cells [46, xx, 18p-] were mutagenized with n-nitrosomethylurea followed by a selection for cycloheximide resistance. two mutants resistant against the drug were selected from either wildtype. 80s ribosomes and their ribosomal subunits were isolated from all mutant and wildtype cells. 80s ribosomes reassociated from the isolated subunits were as active as isolated 80s couples in the poly (u) dependent poly (phe) synthesis. hyb ...1979292826
hybrid mammalian cells assemble hybrid ribosomes.hybrid cell lines formed by fusion of mouse 3t3 cells and chinese hamster ovary (cho) cells resistant to emetine, which have an altered 40s ribosomal protein, are generally sensitive to emetine. from most hybrid lines it was possible to select sublines resistant to emetine. the ribosomal components of three lines were studied: a34, an emetine-sensitive hybrid; a34/r3, an emetine-resistant derivative of a34; and a72, an emetine-sensitive hybrid that did not give rise to emetine-resistant sublines ...1979293661
amplified dihydrofolate reductase genes in unstably methotrexate-resistant cells are associated with double minute chromosomes.selection of mammalian cells in progressively increasing concentrations of methotrexate results in selective amplification of dna sequences coding for dihydrofolate reductase (tetrahydrofolate dehydrogenase, 5,6,7,8-tetrahydrofolate:nadp+ oxidoreductase, ec in some cell variants the amplified genes are stable with growth in the absence of methotrexate, whereas in other variants the amplified genes are lost from the population. we have previously reported that in a stably amplified vari ...1979293670
genetic and biochemical analysis of the a1 cell-surface antigen associated with human chromosome 11.a highly versatile system for genetic, biochemical, and immunological analysis of human cell surface components has been developed using a human-chinese hamster somatic cell hybrid containing chromosome 11 as its only human chromosome. this system lends itself to studies such as identification of human cell surface antigens and other genetic markers, regional gene mapping of these markers on chromosome 11, mutational analysis of these markers, and exploration of distribution of these antigens in ...1979293736
influence of crystallization habit of minerals on in vitro cytotoxicity.four samples of cummingtonite-grunerite series in various crystallization habits were tested in vitro. the cytotoxicity to chinese hamster ovary cells and hemolysis to sheep erythrocytes were inversely proportional to the structural faults and surface defects of the minerals. at a comparable surface area, asbestiform grunerite (uicc amosite), semi-asbestiform cummingtonite, acicular cummingtonite, and acicular grunerite were found to be cytotoxic and hemolytic in a decreasing order. the influenc ...1979294214
the effect of bromodeoxyuridine on the segregation of the chicken-specific hprt gene from chinese hamster-chick red blood cell somatic hybrids.the segregation of the chick-specific hprt gene was studied in three chinese hamster-chick red blood cell hybrid lines. the three lines showed individual segregation kinetics, the segregation taking place in an exponential-like fashion. bromodeoxyuridine becomes incorporated into the nuclear dna and increases the spontaneous segregation rate.1978299650
rescue of marker phenotypes mediated by somatic cell hybridization.the effect of irradiation prior to virus-induced cell fusion on the frequency of hybrid production has been measured as a function of radiation dose. the chinese hamster line wg3h (hgprt-) was crossed with the tk- mutants; chinese hamster a23 or mouse 3t34e, and hybrids were selected in hat medium. irradiation of one (marker rescue) or both (mutual rescue) partners before fusion yielded qualitatively different results. after x-irradiation marker rescue curves were of single-hit type, with d0 val ...1977300369
comparison of three mammalian cell-lines with respect to their sensitivities to hyperthermia, gamma-rays and u.v.-radiation.three types of cultured mammalian cells, from a rat ureter carcinoma (ruc-2), from a mouse mammary carcinoma (m8013), and from a chinese hamster lung cell-line (ch-v79), have been compared with respect to various treatments. using cloning assay, the sensitivity of these cell-lines was measured for ionizing radiation, u.v.-light and for temperatures of 41 degrees, 42 degrees, 43 degrees, 44 degrees and 45 degrees c. ruc-2 cells are the least sensitive to these treatments, except for 45 degrees c. ...1977301514
inactivation and mutation of cultured mammalian cells by aluminium characteristic ultrasoft x-rays. ii. dose-responses of chinese hamster and human diploid cells to aluminium x-rays and radiations of different let.the induction of inactivation and mutation to thioguanine-resistance of two types of cultured mammalian cells, v79 chinese hamster and hf19 human diploid, was studied after irradiation with aluminium k characteristic ultrasoft x-rays, helium ion track intersections of different let, 42 mev d-be neutrons, and hard x- or gamma-rays. the form of the dose-response curves was different for the two cell-types, and there was an overall difference in radiosensitivity, the human cells being the more sens ...1977301865
inactivation and mutation of cultured mammalian cells by aluminium characteristic ultrasoft x-rays. iii. implication for theory of dual radiation action.microdosimetric distributions for aluminium k characteristic ultrasoft x-rays and 4he ion tract intersections are calculated and used to analyse recent biological results obtained with these radiations. results on inactivation and mutation-induction to thioguanine resistance of both v79 chinese hamster cells and hf19 human diploid fibroblasts in vitro are analysed in terms of the kellerer-rossi "theory of dual radiation action". the small quantum energy of the aluminium x-ray photons and the ver ...1977301870
effect of salt solutions on radiosensitivity of mammalian cells. iii. treatment with hypertonic solutions.v79 chinese hamster cells were treated with hypertonic solutions of nacl or kcl and irradiated rat various times before, during, or after exposure to the solution. in solutions of molarities between 0-2 and 0-5 m, the cellular radiosensitivity increases with the molarity of the bathing solution. at these molarities, the hypertonic solution need not be present during irradiation to sensitize cells. furthermore, radiosensitivity of cells could be increased by exposing cells for longer times to the ...1977302244
thermal enhancement of the effectiveness of gamma radiation for induction of reproductive death in cultured mammalian cells.the induction by gamma radiation of reproductive death in cultured cells derived from a rat ureter carcinoma (ruc-2) and from chinese-hamster lung tissue (ch-v79) was shown to be enhanced by hyperthermic treatments at 41, 43 and 45 degrees c. the degree of enhancement was found to depend on the line of cells studied, the temperature employed and the level of damage considered. the influence of accumulating sublethal damage was decreased by hyperthermia, and the final slope of the radiation survi ...1978309451
host range restriction of vaccinia virus in chinese hamster ovary cells: relationship to shutoff of protein synthesis.chinese hamster ovary cells were found to be nonpermissive for vaccinia virus. although early virus-induced events occurred in these cells (rna and polypeptide synthesis), subsequent events appeared to be prevented by a very rapid and nonselective shutoff of protein synthesis. within less than 2 h after infection, both host and viral protein syntheses were arrested. at low multiplicities of infection, inhibition of rna synthesis with cordycepin resulted in failure of the virus to block protein s ...1978310474
effectiveness of 0.3 kev carbon ultrasoft x-rays for the inactivation and mutation of cultured mammalian cells.carbon k characteristic ultrasoft x-rays of energy 0.278 kev were found to be effective in inducing inactivation and mutation to thioguanine resistance in cultured v79 chinese hamster cells and human diploid fibroblasts. these x-rays act as a probe of the sensitive sites within the cells since they produce low-energy photoelectron tracks of range about 7 nm; this is an order of magnitude smaller than those produced by the 1.5 kev aluminium x-rays used in previous studies. a detailed interpretati ...1979315385
mutation and inactivation of cultured mammalian cells exposed to beams of accelerated heavy ions. i. irradiation facilities and methods.this paper, which is the first of four covering the inactivation of clonogenic capacity and induction of mutation in cultured mammalian cells, deals briefly with the general aims of the work and describes the irradiation techniques used. human diploid fibroblasts and v79 chinese hamster cells were irradiated as monolayers with ions of helium, boron or nitrogen at let's in the range 20 to 479 kev micrometer-1 in h2o. the physical aspects of the irradiation including measurement of ion energies, d ...1979315387
regional assignment of seven genes on chromosome 1 of man by use of man-chinese hamster somatic cell hybrids. ii. results obtained after induction of breaks in chromosome 1 by x-irradiation.the position of genes coding for pgd, pph1, ugpp, guk1, pgm1, pep-c, and fh on human chromosome 1 was investigated by analysis of karyotype and enzyme phenotypes in man-chinese hamster somatic cell hybrids carrying aberrations involving chromosome 1. suitable hybrid cell lines were obtained by x-irradiation of hybrid cells carrying an intact chromosome 1 and by fusion of human cells from a clonal population carrying a translocation involving chromosome 1 with chinese hamster cells. the latter hu ...1977318153
mannosidosis: assignment of the lysosomal alpha-mannosidase b gene to chromosome 19 in man.human alpha-mannosidase activity (alpha-d-mannoside mannohydrolase, ec from tissues and cultured skin fibroblasts was separated by gel electrophoresis into a neutral, cytoplasmic form (alpha-mannosidase a) and two closely related acidic, lysosomal components (alpha-mannosidase b). human mannosidosis, an inherited glycoprotein storage disorder, has been associated with severe deficiency of both lysosomal alpha-mannosidase b molecular forms. chromosome assignment of the gene coding for h ...1977318154
the effect of respiratory carcinogenesis on systemic humoral and cell-mediated immunity of syrian golden hamsters.the effect of intratracheal instillation of benzo(a)pyrene and its noncarcinogenic analog benzo(a)pyrene on the systemic humoral and cell-mediated immune response of syrian golden hamsters was evaluated. hamsters treated with the carcinogen had a transient suppression of the splenic plaque-forming cell response to sheep erythrocytes, compared with analog-treated controls. the numbers of direct (immunoglobulin m) and indirect (immunoglobulin g) plaque-forming cells were suppressed at the 9th week ...1977318605
enterotoxigenic escherichia coli isolated from patients at a hospital in dacca.enterotoxigenic strains of escherichia coli, a significant cause of acute, watery, cholera-like diarrhea, were isolated from 23 of 65 patients with diarrhea in whom no other enteric pathogens were found during one week (november 1974) at the cholera research hospital, dacca, bangladesh. diarrhea associated with enterotoxigenic strains of e. coli occurred primarily in adults but affected persons of all age groups and could not be distinguished from cholera or from other cholera-like diarrhea on c ...1977320276
microsome-mediated mutagenesis in v79 chinese hamster cells by various nitrosamines.a microsome-mediated mutagenesis system has been established with the v79 chinese hamster cell line. the cells, grown in monolayer, were treated with various nitrosamines in the presence of a postmitochondrial fraction ((s15) from rat liver and a reduced nicotinamide adenine dinucleotide-generating system for 1 hr, washed and incubated for 2 to 3 hr in fresh culture medium, and then plated for toxicity and mutagenicity assays. mutation was determined by resistance to 20mug 8-azaguanine per ml. i ...1977321116
diarrhea due to escherichia coli in the rabbit: a novel mechanism.a strain of escherichia coli o15 (rdec-1) isolated from several rabbits with diarrhea was examined to determine (1) whether the strain could produce diarrhea when administered by the orogastric route to other rabbits and (2) whether this strain was invasive or enterotoxigenic. strain rdec-1 produced diarrhea in 48 of 62 rabbits when given by the orogastric route in doses that ranged from 1.5 x 10(2) to 4 x 10(10) bacteria. the organism did not give a positive result in the 18-hr ileal loop or se ...1977321703
characterization of the chinese hamster ovary cell assay for the enterotoxins of vibrio cholerae and escherichia coli and for specific antisera, and toxoid.the morphologic change in chinese hamster ovary (cho) cells that is associated with increased intracellular concentrations of adenosine 3':5'-cyclic phosphate (cyclic amp) provided a highly sensitive assay for the heat-liable enterotoxins of vibrio cholerae and escherichia coli. the similarity between the responses of cho cells and those of intestinal mucosa to enterotoxins was demonstrated by the inhibition of these effects by the ganglioside galactosyl-n-acetylgalactosaminyl [sialosyl] lactosy ...1977323378
mutagenicity of polycyclic hydrocarbons. ii. monitoring genetical hazards of chrysene in vitro and vivo.mutagenicity tests were performed with chrysene in the salmonella/microsome test, nmri-mice oocytes, bone-marrow cells and spermatogonia of chinese hamsters. only in mice oocytes was a weak but significant increase of structural chromosome aberrations observed. correlations were found between weak carcinogenic and observed weak mutagenic activities of chrysene in vitro and in vivo.1977327309
mutagenicity and cytotoxicity of benz[alpha]anthracene diol epoxides and tetrahydro-epoxides: exceptional activity of the bay region 1,2-epoxides.three diastereomeric pairs of diol epoxides, two tetrahydro-epoxides, and the k-region oxide of the polycyclic aromatic hydrocarbon benz[a]anthracene were evaluated for mutagenic activity in strain ta 100 of salmonella typhimurium and in line v79-6 of chinese hamster lung cells. the two diastereomeric 1,2-epoxides of the trans-3,4-dihydrodiol of benz[a]anthracene are 15 to 35 times more mutagenic to the bacteria and 65 to 125 times more mutagenic to the mammalian cells than are the diastereomeri ...1977331315
mutagenicity of isomeric diol-epoxides of benzo[a]pyrene and benz[a]anthracene in s. typhimurium ta98 and ta100 and in v79 chinese hamster cells.pairs of isomeric vicinal diol-epoxides derived from benzo[a]pyrene 7,8- and 9,10-dihydrodiols and from benz[a]anthracene 8,9-dihydrodiol were tested for their abilities to revert salmonella typhimurium strains ta98 and ta100 to histidine prototrophy and to induce the formation of 8-azaguanine- or of ouabain-resistant v79 chinese hamster cells. all six diol-epoxides were active in both bacterial strains, but 7beta,8alpha-dihydroxy-9beta,10beta-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (the syn iso ...1977333280
zinc and manganese contents of micro-dissected pancreatic islets of some rodents. a microchemical study in adult and newborn guinea pigs, rats, chinese hamsters and spiny a flameless atomic absorption spectrophotometry procedure, using a graphite furnace, it was possible to assay the contents of zinc and managanese in micro-dissected pancreatic islets of several rodents. interest was focused upon the islets of guinea-pigs, due to the fact that guinea-pig insulin lacks a histidine residue in the b10 position of the molecule which normally binds zinc (or other heavy metals) in the hexamer formation, probably involved in the storage of insulin. both the zinc and ...1977335757
escherichia coli heat-labile enterotoxin: comparison of antitoxin assays and serum antitoxin levels.the mouse adrenal tumor cells (y-1 strain) and the chinese hamster ovary cells, two routinely used tissue culture assays for escherichia coli heat-labile enterotoxin (lt), were used to detect serum antitoxin responses in culture-positive patients from several well-defined sources. there was no correlation between a significant antitoxin response and isolation of lt-producing e. coli in two "domestic" diarrheal outbreaks. serum samples from a third group of individuals in a rural cholera-endemic ...1977336543
toxin from the culture filtrate of shigella dysenteriae that causes morphological changes in chinese hamster ovary cells and is distinct from the neurotoxin.a toxin that causes morphological changes in chinese hamster ovary cells was isolated from a culture filtrate of shigella dysenteriae 1. it was partially purified by successive column chromatography on diethylaminoethyl-cellulose, bio-gel a-5m, and hydroxylapatite. the toxin was separated from neurotoxin by diethylaminoethyl-cellulose column chromatography and was not lethal for mice.1977336549
inhibition of mammalian ribonucleotide reductase by a dinucleotide produced in eucaryotic cells.hs3, a highly phosphorylated dinucleoside originally purified from the fungus achlya, has been isolated from chinese hamster ovary cells undergoing glutamine starvation. the hs3 compounds obtained from the fungal and mammalian sources exhibited similar physical and chemical properties. this unusual dinucleotide may be an important regulator of eucaryotic ribonucleoside diphosphate reductase activity; for 50 micrometer hs3, isolated from either mammalian or fungal cells, significantly inhibited c ...1977338619
assignment of the structural genes for the alpha subunit of hexosaminidase a, mannosephosphate isomerase, and pyruvate kinase to the region q22-qter of human chromosome 15.concordant segregation of the expression of the alpha subunit of human hexosaminidase a, human mannosephosphate isomerase, and pyruvate kinase was observed in somatic cell hybrids between either thymidine kinase-deficient mouse cells or thymidine kinase-deficient chinese hamster cells and human white blood cells carrying a translocation of the distal half (q 22-qter) of the long arm of chromosome 15 to chromosome 17. a positive correlation was established between the expression of these human ph ...1977341373
replica plating and in situ enzymatic assay of animal cell colonies established on filter paper.we have developed a simple technique for the replica plating of chinese hamster ovary (cho) cells. in this procedure cells are allowed to divide for 8-16 days between the plastic surface of a petri dish and a disc of whatman no. 50 filter paper, weighted down with glass beads. the culture medium can be replaced when necessary without disturbing the growing colonies. cells from each developing colony grow into the fibers of the paper, while others remain attached to the plate. the cell colonies t ...1978349559
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