Sample records for 基因增殖 (gene amplification)

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Type 1 transforming growth factor beta: amplified expression and secretion of mature and precursor polypeptides in Chinese hamster ovary cells.

Purchio, A F; Brunner, A M; Gentry, L E; Lim, G J; Webb, N R; Ranchalis, J E; Marquardt, H; Twardzik, D R; Lioubin, M N

Recombinant type 1 transforming growth factor beta (TGF-beta) was expressed to high levels in CHO cells by using dihydrofolate reductase (dhfr) gene amplification. The expression plasmid was derived from the pSV2 vectors and contained, in tandem, the simian TGF-beta and mouse dhfr cDNAs. Transcripti...

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Transient hypoxia enhances the frequency of dihydrofolate reductase gene amplification in Chinese hamster ovary cells.

Rice, G C; Schimke, R T; Hoy, C

Exposure of Chinese hamster cells to reduced oxygen partial pressure results in a marked enhancement in the frequency of methotrexate resistance and dihydrofolate reductase gene amplification. The frequency of enhanced resistance is a function of the length of exposure to hypoxic conditions and the ...

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Transfer and amplification of a mutant beta-tubulin gene results in colcemid dependence: use of the transformant to demonstrate regulation of beta-tubulin subunit levels by protein degradation.

Gottesman, M M; Whitfield, C; Ascherman, D; Abraham, I

Total genomic DNA from a temperature-sensitive, colcemid-resistant Chinese hamster ovary (CHO) cell mutant expressing an electrophoretic variant beta-tubulin was used to transform wild-type CHO cells to colcemid-resistant cells at 37 degrees C. Southern blot analysis of the transformant demonstrated...

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Transcription of mouse rDNA and associated formation of the nucleolus organizer region after gene transfer and amplification in Chinese hamster cells.

Dhar, V N; Miller, O J; Miller, D A

Mouse rDNA can initiate transcription by using only Chinese hamster cell components, and this is associated with nucleolus organizer activity. To demonstrate this, we transferred a 3.2-kilobase segment of mouse rDNA containing the promoter, the transcription initiation site, and part of the external...

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The multicopy appearance of a large inverted duplication and the sequence at the inversion joint suggest a new model for gene amplification.

de Saint Vincent, B R; Hyrien, O; Buttin, G; Debatisse, M

The amplified DNA of HC50474, a Chinese hamster fibroblast cell line selected in three steps for high resistance to coformycin, consists chiefly of 150 copies of a large inverted duplication including the adenylate deaminase gene. Most if not all of these units are more than 2 x 120 kb long. The inv...

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Selective amplification of polymorphic dihydrofolate reductase gene loci in Chinese hamster lung cells.

Lewis, J A; Melera, P W; Davide, J P

A series of antifolate-resistant Chinese hamster lung sublines that overproduce either a Mr 20,000 or a Mr 21,000 class of dihydrofolate reductase (DHFR; tetrahydrofolate dehydrogenase; 5,6,7,8-tetrahydrofolate:NADP+ oxidoreductase, EC, known to contain amplified DHFR genes, has been analyz...

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Overproduction of dihydrofolate reductase and gene amplification in methotrexate-resistant Chinese hamster ovary cells.

Essani, A K; Flintoff, W F; Nagainis, C R; Weber, M K; Robertson, D; Salser, W

Stable isolates of Chinese hamster ovary cells that are highly resistant to methotrexate have been selected in a multistep selection process. Quantitative immunoprecipitations have indicated that these isolates synthesize dihydrofolate reductase at an elevated rate over its synthesis in sensitive ce...

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Multidrug-resistant phenotype cosegregates with an amplified gene in somatic cell hybrids of drug-resistant Chinese hamster ovary cells and drug-sensitive murine cells.

Stallings, R L; Teeter, L D; Sen, S; Sanford, J A; Siciliano, M J; Kuo, M T

Gene amplification has been associated with multidrug resistance (MDR) in several drug-resistant Chinese hamster ovary (CHO) cell lines which exhibit cross-resistance to other unrelated, cytotoxic drugs. In situ hybridization studies (Teeter et al., J. Cell Biol., in press) suggested the presence of...

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Molecular events in the processing of recombinant type 1 pre-pro-transforming growth factor beta to the mature polypeptide.

Marquardt, H; Gentry, L E; Purchio, A F; Lioubin, M N

Recently, the simian type 1 transforming growth factor beta (TGF-beta 1) cDNA was expressed at high levels in Chinese hamster ovary (CHO) cells by dihydrofolate reductase-induced gene amplification (L.E. Gentry, N.R. Webb, G.J. Lim, A.M. Brunner, J.E. Ranchalis, D.R. Twardzik, M.N. Lioubin, H. Marqu...

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Moderate-level gene amplification in methotrexate-resistant Chinese hamster ovary cells is accompanied by chromosomal translocations at or near the site of the amplified DHFR gene.

Worton, R G; Flintoff, W F; Duff, C; Livingston, E

In previous studies, we have described several classes of methotrexate-resistant Chinese hamster ovary cell lines. Although the RI class is resistant because of an altered target enzyme, dihydrofolate reductase, the RIII class derived from RI cells is somewhat more resistant because of a moderate am...

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Laser capture microdissection combined with RNA in vitro Linear amplification detecting the relevant genes of bladder cancer

Hao, Q; Xu, Y; Li, W; Zhao, X; Liu, W

Objective: Laser capture microdisection has become indispensable to the analysis of the difference of gene expression between human bladder transitional cell and bladder transitional cell carcinoma(BTCC). However, to obtain sufficient RNA from laser-capture microdissected cells is quite difficult. T...

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Laser capture microdissection combined with RNA in vitro Linear amplification detecting the relevant genes of bladder cancer

Hao, Q; Xu, Y; Li, W; Zhao, X; Liu, W

Objective: Laser capture microdisection has become indispensable to the analysis of the difference of gene expression between human bladder transitional cell and bladder transitional cell carcinoma(BTCC). However, to obtain sufficient RNA from laser-capture microdissected cells is quite difficult. T...

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Initiation of DNA replication at the Chinese hamster origin oriGNAI3 relies on local sequences and/or chromatin structures, but not on transcription of the nearby GNAI3 gene.

Debatisse, M; Toledo, F; Mayau, V; Lachagès, A M

We recently identified a region of preferential replication initiation, oriGNAI3, near the 3' end of the Chinese hamster GNAI3 gene. oriGNAI3 is co-amplified in mutants selected for AMPD2 amplification, a process generating chromosomal rearrangements. In this report we have taken advantage of cell l...

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Hairpin structures are the primary amplification products: a novel mechanism for generation of inverted repeats during gene amplification.

Lavi, S; Cohen, S; Karby, S; Hassin, D

Early events of DNA amplification which occur during perturbed replication were studied by using simian virus 40 (SV40)-transformed Chinese hamster cells (CO60) as a model system. The amplification is observed shortly after carcinogen treatment, and the amplified sequences contain molecules organize...

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Detection and characterisation of beta-globin gene cluster deletions in Chinese using multiplex ligation-dependent probe amplification

So, CC; So, ACY; Chan, AYY; Tsang, STY; Ma, ESK; Chan, LC

BACKGROUND: Deletions in the beta-globin cluster causing thalassaemia and hereditary persistence of fetal haemoglobin (HPFH) are uncommon and difficult to detect. Data in Chinese are very scarce. AIMS: To use a recently available technique to investigate the frequencies and nature of beta-globin clu...

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Deletion and amplification of the HGPRT locus in Chinese hamster cells.

Caskey, C T; Fuscoe, J C; Ledbetter, D H; Fenwick, R G

Somatic cell selective techniques and hybridization analyses with a cloned cDNA probe were used to isolate and identify Chinese hamster cell lines in which the X-linked gene for hypoxanthine-guanine phosphoribosyltransferase (HGPRT) has been altered. Two of 19 HGPRT-deficient mutants selected were f...

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

Tesmer, J G; Munk, A C; Griffith, J K; Crawford, B D; Walters, R A; Griffith, B B; Enger, M D; Hanners, J L; Stallings, R L

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 cor...

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Clinical and pathological characteristics of Chinese patients with BRCA related breast cancer

Kwong, Ava; Wong, P. L.; Wong, N. H.; Law, F. B. F.; Ng, O. K. E.; Tang, H. Y.; Chan, K. W.; Suen, K. T. D.; Choi, C.

Breast cancers related to BRCA mutations are associated with particular biological features. Here we report the clinical and pathological characteristics of breast cancer in Chinese women with and without BRCA mutations and of carriers of BRCA1 mutations compared to BRCA2 mutations. Two hundred and ...

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Chromosome-mediated gene transfer of hydroxyurea resistance and amplification of ribonucleotide reductase activity.

Lewis, W H; Srinivasan, P R

Metaphase chromosomes purified from a hydroxyurea-resistant Chinese hamster cell line were able to transform recipient wild-type cells to hydroxyurea resistance at a frequency of 10(-6). Approximately 60% of the resulting transformant clones gradually lost hydroxyurea resistance when cultivated for ...

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Chromosome breakage at a major fragile site associated with P-glycoprotein gene amplification in multidrug-resistant CHO cells.

Hittelman, W N; Kuo, M T; Jiang, L X; Vyas, R C

Recent studies of several drug-resistant Chinese hamster cell lines suggested that a breakage-fusion-bridge mechanism is frequently involved in the amplification of drug resistance genes. These observations underscore the importance of chromosome breakage in the initiation of DNA amplification in ma...

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Chromosomal localization of the murine RFC-1 gene encoding a folate transporter and its amplification in an antifolate resistant variant overproducing the transporter

Roy, K; Chiao, JH; Spengler, BA; Tolner, B; Yang, CH; Biedler, JL; Sirotnak, FM

\A variant of the L1210 cell (L1210/R83) selected in the presence of the lipophilic antifolate, metoprine, and a concentration of the natural diastereoisomer of 5-formyltetrahydrofolate, lLCHO-folateH(4), suboptimum for growth exhibited a 35-fold increase compared to parental L1210 cells in one-carb...

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Characterization and quantification of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in a nitrogen-removing reactor using T-RFLP and qPCR

Jin, Tao; Zhang, Tong; Yan, Qingmei

Using ammonia monooxygenase α-subunit (amoA) gene and 16S rRNA gene, the community structure and abundance of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in a nitrogen-removing reactor, which was operated for five phases, were characterized and quantified by cloning, termina...

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Assignment of genes encoding metallothioneins I and II to Chinese hamster chromosome 3: evidence for the role of chromosome rearrangement in gene amplification.

Hildebrand, C E; Stallings, R L; Longmire, J L; Munk, A C; Crawford, B D

Cadmium resistant (Cdr) variants with coordinately amplified metallothionein I and II (MTI and MTII) genes have been derived from both Chinese hamster ovary and near-euploid Chinese hamster cell lines. Cytogenetic analyses of Cdr variants consistently revealed breakage and rearrangement involving ch...

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An amplified chromosomal sequence that includes the gene for dihydrofolate reductase initiates replication within specific restriction fragments.

Heintz, N H; Hamlin, J L

We have developed a methotrexate-resistant Chinese hamster ovary cell line (CHOC 400) containing a 500-fold amplification of a 135-kilobase chromosomal DNA sequence. This sequence includes the gene for dihydrofolate reductase (tetrahydrofolate dehydrogenase, 5,6,7,8-tetrahydrofolate: NADP+ oxidoredu...

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Amplification of the human dihydrofolate reductase gene via double minutes is initiated by chromosome breaks

Trask, Barbara J.; Singer, Michael J.; Friedman, Cynthia L.; Mesner, Larry D.; Hamlin, Joyce L.

DNA sequence amplification is one of the most frequent manifestations of genomic instability in human tumors. We have shown previously that amplification of the dihydrofolate reductase (DHFR) gene in Chinese hamster cells is initiated by chromosome breaks, followed by bridge-breakage-fusion cycles t...

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Amplification of the gene for histidyl-tRNA synthetase in histidinol-resistant Chinese hamster ovary cells.

Siminovitch, L; Tsui, F W; Murialdo, H; Andrulis, I L

Histidinol-resistant (HisOHR) mutants with up to a 30-fold increase in histidyl-tRNA synthetase activity have been isolated by stepwise adaptation of wild-type Chinese hamster ovary (CHO) cells to increasing amounts of histidinol in the medium. Immunoprecipitation of [35S]methionine-labeled cell lys...

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Amplification of the IMP dehydrogenase gene in Chinese hamster cells resistant to mycophenolic acid.

Collart, F R; Huberman, E

The regulation of IMP dehydrogenase (IMPDH) was analyzed in Chinese hamster V79 cell variants that exhibit different degrees of resistance to the cytotoxic effect of mycophenolic acid, a specific inhibitor of IMPDH. Western blot (immunoblot) analysis with an IMPDH antiserum revealed a 14- to 27-fold...

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Amplification of a cloned Chinese hamster dihydrofolate reductase gene after transfer into a dihydrofolate reductase-deficient cell line.

Milbrandt, J D; Hamlin, J L; Azizkhan, J C

We have transformed a dihydrofolate reductase (DHFR)-deficient Chinese hamster ovary cell line to the DHFR+ phenotype with a recombinant cosmid (cH1) containing a functional Chinese hamster DHFR gene (J.D. Milbrandt et al., Mol. Cell. Biol. 3:1266-1273, 1983). After exposure of cells to successive i...

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Amplification and expression of human alpha-globin genes in Chinese hamster ovary cells.

Lau, Y F; Kan, Y W; Lin, C C

We studied the effects of gene amplification on human globin gene expression in Chinese hamster ovary cells. The normal human alpha-globin gene (N alpha 2) and a hybrid gene (M alpha G) containing the 5' promoter-regulator region of the mouse metallothionein gene and the human structural alpha 2-glo...

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Amplification and cloning of the Chinese hamster glutamine synthetase gene.

Sanders, P G; Wilson, R H

A Chinese hamster ovary cell line, KG1MS which is resistant to 5 mM methionine sulphoximine overproduces glutamine synthetase. Overproduction of this 42 000 mol. wt. polypeptide is not seen in either parental KG1 or revertant KG1MSC4-0 cell lines which are resistant to 3 microM and 8 microM methioni...

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Aberrante Methylierung des p16INK4a-Promotors als Tumormarker für die molekularzytologische Diagnostik des Lungenkarzinoms an Bronchialaspiraten

Krücken, Anne

In der vorliegenden Arbeit wurde der Methylierungsstatus des p16INK4a-Promotors an Material der pulmonalen Exfoliativzytologie untersucht und seine Eignung als Tumormarker für die molekularzytologische Diagnostik des Lungenkarzinoms überprüft. Der Nachweis der p16INK4a-Promotor-Methylierung erfolgte...

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