scholarly journals SITES OF NUCLEOLUS PRODUCTION IN CULTURED CHINESE HAMSTER CELLS

1969 ◽  
Vol 40 (1) ◽  
pp. 248-268 ◽  
Author(s):  
Stephanie Gordon Phillips ◽  
David M. Phillips
Keyword(s):  
Fine Structure ◽  
Ribosomal Rna ◽  
Rna Synthesis ◽  
Chinese Hamster ◽  
Cell Types ◽  
Chinese Hamster Cell ◽  
Chinese Hamster Cells ◽  
Cell Strains ◽  
Almost All ◽  
Nucleolar Components

Chinese hamster cell strains in the early passages in culture display wide variation in number of nucleolus-like bodies per cell, though such strains are characteristically euploid. A variety of criteria indicate that the nucleolus-like bodies are true nucleoli. Their Azure B- and fast green-staining properties indicate the presence of RNA and protein; they have typical nucleolar fine structure, including both fibrous and granular components; radioautography reveals that their patterns of uptake of uridine-3H into RNA are similar to those reported for nucleoli of other cell types; actinomycin D, at a level which selectively inhibits ribosomal RNA synthesis, greatly reduces their RNA synthesis and also causes segregation of fibrous and granular nucleolar components. Colchicine was used to experimentally fragment the nuclei of these cells into a number of separate karyomeres, each presumably containing some, or only one, of the chromosomes of the complement. Almost all the karyomeres contain nucleolus-like bodies which, by the same criteria applied to the multiple nucleolus-like bodies of uninuclear cells, appear to be true nucleoli. The nucleoli of individual karyomeres of the same cell often differ from each other in fine structure while the multiple nucleoli of a uninuclear cell generally resemble each other. The evidence presented in this study indicates that Chinese hamster cells contain many nucleolus-producing sites scattered through the genome.

scholarly journals NUCLEOLI OF DIPLOID CELL STRAINS

1971 ◽  
Vol 49 (3) ◽  
pp. 785-802 ◽  
Author(s):  
Stephanie G. Phillips ◽  
David M. Phillips
Keyword(s):  
Ribosomal Rna ◽  
Rna Synthesis ◽  
Actinomycin D ◽  
Chinese Hamster ◽  
Diploid Cell ◽  
Particulate Material ◽  
Gradual Disappearance ◽  
Mouse Cells ◽  
Cell Strains ◽  
Nucleolar Components

Nucleoli of cultured Chinese hamster or mouse cells in early passages had a loosely reticular substructure. Within the reticulum small, irregularly shaped, light fibrillar zones occurred which were contiguous with denser fibrillar zones. These denser zones appeared to be connected in some places to the particulate material which composed the mass of the nucleolus. Generally, electron-transparent spaces separated the particulate zones from the fibrillar areas. Treatment with toyocamycin, an agent which is reported to cause a blockage in the processing of ribosomal RNA, greatly inhibited the accumulation of newly synthesized RNA in the cytoplasm, as monitored by radioautography. Toyocamycin treatment caused the gradual disappearance of the granules from the particulate region of the nucleoli, and resulted ultimately in the nucleoli appearing homogeneously fibrillar. Actinomycin D treatment, which inhibited virtually all RNA synthesis, caused a segregation, and finally a disaggregation, of nucleolar components.

scholarly journals RNA SYNTHESIS IN CHINESE HAMSTER CELLS

1968 ◽  
Vol 36 (3) ◽  
pp. 583-593 ◽  
Author(s):  
M. D. Enger ◽  
R. A. Tobey ◽  
A. G. Saponara
Keyword(s):  
Ribosomal Rna ◽  
Rna Synthesis ◽  
Specific Activity ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Sedimentation Analysis ◽  
Ovary Cells ◽  
Chinese Hamster Cells ◽  
Mechanical Selection ◽  
Selection Of

The incorporation of methionine-methyl-14C into 18S ribosomal RNA of cultured Chinese hamster ovary cells in early and late interphase has been determined by zone-sedimentation analysis of phenol-extracted RNA preparations. Synchronized cell cultures were prepared for these studies by thymidine treatment and by mechanical selection of mitotic cells. The specific activity of 18S RNA labeled in late interphase was found to be 1.1–1.2 times that of 18S RNA labeled in early interphase. Upon correction for increase in RNA mass, the rate of methylation of 18S RNA in late interphase is about 1.9 times that in early interphase.

THE ESTABLISHMENT AND CHROMOSOME ANALYSIS OF A NEW CELL LINE OF CHINESE HAMSTER FROM SPONTANEOUS TRANSFORMATION IN VITRO

1971 ◽  
Vol 13 (1) ◽  
pp. 9-13 ◽  
Author(s):  
C. C. Lin ◽  
T. D. Chang ◽  
Virginia Niewczas-Late
Keyword(s):  
Cell Line ◽  
Chinese Hamster ◽  
Chromosome Analysis ◽  
Cell Types ◽  
Selective Advantage ◽  
Chinese Hamster Cell ◽  
Major Type ◽  
Spontaneous Transformation ◽  
Chinese Hamster Cell Line

A male Chinese hamster cell line has been established through spontaneous transformation in a skin culture. Chromosome studies at passage 13 revealed one major and one minor type of pseudodiploid cells (77.3 and 20%). At passage 42, only the major subline persisted (78%). The two sublines, especially the major one, had selective advantage over other cell types in this cell line probably because they were more nearly genetically balanced. Autoradiographic studies indicated no overall increase in late replicating chromosomal elements in the two sublines. Both cell types lacked the X chromosome and chromosome 6, but they were largely compensated for by the presence of new marker chromosomes. However, more chromosomal material was missing in the minor type than in the major type, and this may account for the lower adaptability of the former.

Coordinate amplification of metallothionein I and II genes in cadmium-resistant Chinese hamster cells: implications for mechanisms regulating metallothionein gene expression

1985 ◽  
Vol 5 (2) ◽  
pp. 320-329
Author(s):  
B D Crawford ◽  
M D Enger ◽  
B B Griffith ◽  
J K Griffith ◽  
J L Hanners ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
Chinese Hamster Cells ◽  
Future Studies ◽  
Noncoding Regions ◽  
Genes Encoding ◽  
Chinese Hamster Cell Line

We describe here the derivation, characterization, and use of clonal cadmium-resistant (Cdr) strains of the Chinese hamster cell line CHO which differ in their metallothionein (MT) induction capacity. By nondenaturing polyacrylamide gel electrophoresis, we showed that the stable Cdr phenotype is correlated with the augmented expression of both isometallothioneins (MTI and MTII). In cells resistant to concentrations of CdCl2 exceeding 20 microM, coordinate amplification of genes encoding both isometallothioneins was demonstrated by using cDNA MT-coding sequence probes and probes specific for 3'-noncoding regions of Chinese hamster MTI and MTII genes. Molecular and in situ hybridization analyses supported close linkage of Chinese hamster MTI and MTII genes, which we have mapped previously to Chinese hamster chromosome 3. This suggests the existence of a functionally related MT gene cluster in this species. Amplified Cdr variants expressing abundant MT and their corresponding Cds parental CHO cells should be useful for future studies directed toward elucidating the mechanisms that regulate expression of the isometallothioneins.

scholarly journals Inhibition by trioxalen (psoralen) plus near-ultraviolet light of the induction of ornithine decarboxylase in Chinese-hamster cells

1979 ◽  
Vol 183 (1) ◽  
pp. 179-180 ◽  
Author(s):  
Y M Heimer ◽  
E Riklis
Keyword(s):  
Ornithine Decarboxylase ◽  
Rna Synthesis ◽  
Potent Inhibitor ◽  
Chinese Hamster ◽  
Chinese Hamster Cells ◽  
Dna And Rna ◽  
Near Ultraviolet ◽  
Chemical Inhibitors ◽  
Dna And Rna Synthesis ◽  
High Degree

Trioxalen (trimethylpsoralen) plus near-u.v. light, a potent inhibitor of DNA and RNA synthesis, inhibits the induction of ornithine decarboxylase in stationary-phase V79 fibroblasts. It does not affect the translation of pre-existing mRNA. The method, in view of its high degree of specificity and precise timing, is a better choice for inhibiting RNA synthesis than the commonly used chemical inhibitors and precursor analogues.

scholarly journals Adhesion and detachment characteristics of Chinese hamster cell membrane mutants.

1978 ◽  
Vol 76 (1) ◽  
pp. 43-49 ◽  
Author(s):  
R L Juliano
Keyword(s):  
Initial Phase ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
Galactose Oxidase ◽  
Wild Type ◽  
Chinese Hamster Cells ◽  
Altered Cell ◽  
Morphological Differences ◽  
Glass Surfaces ◽  
Surface Glycoproteins

We have investigated the adhesion and detachment properties of wild-type Chinese hamster cells and of variant lines, which possess altered cell surface glycoproteins as detected by galactose oxidase-[3H]borohydride labeling. The wild-type and variant lines tested all adhered to protein-coated glass surfaces at the same rate; however, the variant cells differed from wild type and from each other in terms of the ease with which they were detached by trypsinization. Morphological differences between the various lines were also apparent. Our results suggest that the carbohydrate moieties of the terminal region of surface glycoproteins are not directly involved in the initial phase of cell-to-substratum attachment, but that they may modulate the proteolytic susceptibility of surface components which are involved in cell detachment.

Biochemical evidence for multiple independent emetine resistance genes in Chinese hamster cells

1983 ◽  
Vol 3 (2) ◽  
pp. 198-202
Author(s):  
K Nielsen-Smith ◽  
S McGill ◽  
M Frahm ◽  
D J Roufa
Keyword(s):  
Molecular Basis ◽  
Ribosomal Proteins ◽  
Chinese Hamster ◽  
Chinese Hamster Cell ◽  
Ovary Cell ◽  
Chinese Hamster Cells ◽  
Molecular Product ◽  
Translation Apparatus ◽  
Hybrid Clones

Hybridization-complementation studies indicated that mutations in multiple genes can render Chinese hamster cells resistant to the alkaloid translation inhibitor emetine. Two of the genes, emtA and emtB, recognized in Chinese hamster lung and ovary cell lines, respectively, are known to affect the ribosomes of the cells directly. Although mutations in a third gene, emtC, affect the translation apparatus of Chinese hamster peritoneal cells in vitro (Wasmuth et al., Mol. Cell. Biol. 1:58-65, 1981), the molecular product of the emtC locus remains to be determined. To study the molecular basis for genetic complementation among emetine-resistant Chinese hamster cell mutants, we analyzed ribosomal proteins elaborated by complementing, emetine-sensitive hybrid clones (EmtB X EmtA and EmtB X EmtC) and by emetine-resistant clones that segregated from the hybrids. The electrophoretic forms of ribosomal protein S14 (the emtB gene product) elaborated by these clones indicated that the EmtA and EmtC phenotypes are independent of the emtB locus and that the emtA and emtC loci are not chromosomally linked to emtB.

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