Thymidylate synthase-deficient Chinese hamster cells: a selection system for human chromosome 18 and experimental system for the study of thymidylate synthase regulation and fragile X expression. 1985

R L Nussbaum, and R M Walmsley, and J G Lesko, and S D Airhart, and D H Ledbetter

Chinese hamster lung (CHL) V79 cells already deficient in hypoxanthine phosphoribosyltransferase were exposed to uv light and selected for mutations causing deficiency of thymidylate synthase (TS) by their resistance to aminopterin in the presence of thymidine and limiting amounts of methyl tetrahydrofolate. Three of seven colonies chosen for initial study were shown to be thymidylate synthase deficient (TS-) by enzyme assay, thymidine auxotrophy, and their inability to incorporate labeled deoxyuridine into their DNA in vivo. Complementation analysis of human X TS- hamster hybrids revealed that TS activity segregated with human chromosome 18. Southern analysis of a panel of 14 human X hamster hybrids probed with complementary DNA from mouse TS confirmed the chromosome assignment of TS to human chromosome 18; quantitative Southern blotting using unbalanced human cell lines further localized the gene to 18q21.31----qter. Another hybrid was generated that contained a human X chromosome with the Xq28 folate-dependent fragile site as its only human chromosome in a hamster TS- background. The fragile site could be easily and reproducibly expressed in this hybrid without the use of antimetabolites simply by removing exogenous thymidine from the medium. These TS-deficient cells are useful for: somatic cell genetics as a unique selectable marker for human chromosome 18, studies on regulation of the TS gene, and analysis of the fragile (X) chromosome and other folate-dependent fragile sites.

UI MeSH Term Description Entries
D007621 Karyotyping Mapping of the KARYOTYPE of a cell. Karyotype Analysis Methods,Analysis Method, Karyotype,Analysis Methods, Karyotype,Karyotype Analysis Method,Karyotypings,Method, Karyotype Analysis,Methods, Karyotype Analysis
D008168 Lung Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood. Lungs
D009693 Nucleic Acid Hybridization Widely used technique which exploits the ability of complementary sequences in single-stranded DNAs or RNAs to pair with each other to form a double helix. Hybridization can take place between two complimentary DNA sequences, between a single-stranded DNA and a complementary RNA, or between two RNA sequences. The technique is used to detect and isolate specific sequences, measure homology, or define other characteristics of one or both strands. (Kendrew, Encyclopedia of Molecular Biology, 1994, p503) Genomic Hybridization,Acid Hybridization, Nucleic,Acid Hybridizations, Nucleic,Genomic Hybridizations,Hybridization, Genomic,Hybridization, Nucleic Acid,Hybridizations, Genomic,Hybridizations, Nucleic Acid,Nucleic Acid Hybridizations
D002460 Cell Line Established cell cultures that have the potential to propagate indefinitely. Cell Lines,Line, Cell,Lines, Cell
D002871 Chromosome Banding Staining of bands, or chromosome segments, allowing the precise identification of individual chromosomes or parts of chromosomes. Applications include the determination of chromosome rearrangements in malformation syndromes and cancer, the chemistry of chromosome segments, chromosome changes during evolution, and, in conjunction with cell hybridization studies, chromosome mapping. Banding, Chromosome,Bandings, Chromosome,Chromosome Bandings
D002874 Chromosome Mapping Any method used for determining the location of and relative distances between genes on a chromosome. Gene Mapping,Linkage Mapping,Genome Mapping,Chromosome Mappings,Gene Mappings,Genome Mappings,Linkage Mappings,Mapping, Chromosome,Mapping, Gene,Mapping, Genome,Mapping, Linkage,Mappings, Chromosome,Mappings, Gene,Mappings, Genome,Mappings, Linkage
D002902 Chromosomes, Human, 16-18 The short, submetacentric human chromosomes, called group E in the human chromosome classification. This group consists of chromosome pairs 16, 17, and 18. Chromosomes E,Group E Chromosomes,Chromosome, Group E,Chromosomes, Group E,E Chromosomes, Group,Group E Chromosome
D003412 Cricetulus A genus of the family Muridae consisting of eleven species. C. migratorius, the grey or Armenian hamster, and C. griseus, the Chinese hamster, are the two species used in biomedical research. Hamsters, Armenian,Hamsters, Chinese,Hamsters, Grey,Armenian Hamster,Armenian Hamsters,Chinese Hamster,Chinese Hamsters,Grey Hamster,Grey Hamsters,Hamster, Armenian,Hamster, Chinese,Hamster, Grey
D004262 DNA Restriction Enzymes Enzymes that are part of the restriction-modification systems. They catalyze the endonucleolytic cleavage of DNA sequences which lack the species-specific methylation pattern in the host cell's DNA. Cleavage yields random or specific double-stranded fragments with terminal 5'-phosphates. The function of restriction enzymes is to destroy any foreign DNA that invades the host cell. Most have been studied in bacterial systems, but a few have been found in eukaryotic organisms. They are also used as tools for the systematic dissection and mapping of chromosomes, in the determination of base sequences of DNAs, and have made it possible to splice and recombine genes from one organism into the genome of another. EC 3.21.1. Restriction Endonucleases,DNA Restriction Enzyme,Restriction Endonuclease,Endonuclease, Restriction,Endonucleases, Restriction,Enzymes, DNA Restriction,Restriction Enzyme, DNA,Restriction Enzymes, DNA
D005600 Fragile X Syndrome A condition characterized genotypically by mutation of the distal end of the long arm of the X chromosome (at gene loci FRAXA or FRAXE) and phenotypically by cognitive impairment, hyperactivity, SEIZURES, language delay, and enlargement of the ears, head, and testes. INTELLECTUAL DISABILITY occurs in nearly all males and roughly 50% of females with the full mutation of FRAXA. (From Menkes, Textbook of Child Neurology, 5th ed, p226) FRAXA Syndrome,FRAXE Syndrome,Martin-Bell Syndrome,Fra(X) Syndrome,Fragile X Mental Retardation Syndrome,Fragile X-F Mental Retardation Syndrome,Mar (X) Syndrome,Marker X Syndrome,Mental Retardation, X-Linked, Associated With Fragile Site Fraxe,Mental Retardation, X-Linked, Associated With Marxq28,X-Linked Mental Retardation and Macroorchidism,FRAXA Syndromes,FRAXE Syndromes,Fragile X Syndromes,Marker X Syndromes,Martin Bell Syndrome,Syndrome, FRAXA,Syndrome, FRAXE,Syndrome, Fragile X,Syndrome, Marker X,Syndrome, Martin-Bell,Syndromes, FRAXA,Syndromes, FRAXE,Syndromes, Fragile X,Syndromes, Marker X,X Linked Mental Retardation and Macroorchidism

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