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R S Athwal

Publications and source records attributed to R S Athwal.

43 records · Page 3Linked to original sources
PubMed1984

Transfer of Chinese hamster chromosome 1 to mouse cells and regional assignment of 7 genes: a combination of gene transfer and microcell fusion.

We have used a combination of chromosome-mediated gene transfer and microcell fusion techniques to transfer Chinese hamster chromosome 1 to mouse cells. Microcell hybrids containing a single hamster chromosome were analyzed to map genes on this chromosome. We have confirmed the assignment of seven markers (GSR, NP, EST-D, ADK, PEP-S, PGM2, and PEP-B) to hamster chromosome 1. Segregation among the linked markers was induced by X irradiation followed by selection for the retention or loss of human hprt. Cosegregation of markers in independent subclones made it possible to determine the gene order for the seven loci. The gene order proposed for these loci is as follows: pter-GSR-NP-EST-D-ADK-(PEP-S, PGM2)-PEP-B-qter. In addition GSR, NP, EST-D, and ADK have been assigned to pter-1q12; PEP-S and PGM2 to 1q12-1q21, and PEP-B to 1q32-1qter. These regional assignments and gene order on chromosome 1 have provided the information relevant to the linkages conserved between Chinese hamster, mouse, and man.

Adenosine Kinase↗
PubMed1982

Measurement of transcribed human X-chromosomal DNA sequences transferred to rodent cells by chromosome-mediated gene transfer.

Transfer of genetic information can be effected by incubation of cultured eucaryotic cells with isolated metaphase chromosomes. In most cases, a resulting transformed cell contains only a fragment of a donor chromosome. The amount of transferred donor DNA has been quantified in 11 independent mouse A9 transformants by nucleic acid hybridization analysis. Each transformant had been selected for hprt (hypoxanthine phosphoribosyltransferase; EC 2.4.2.8) transfer and contained part of the human X chromosome. A labeled probe of transcribed human X-chromosomal DNA was prepared by hybridization of nick-translated unique-sequence human DNA with whole cellular RNA from a human-mouse hybrid cell line, A9/HRBC2-A, containing a single human chromosome., X. The amount of human X-chromosomal DNA in the transformants was quantitated by comparing the hybridization of this probe with transformant and A9/HRBC2-A DNAs. Two unstable transformants which had a microscopically detectable donor chromosome fragment contained 15% of the human X-chromosomal single-copy DNA. Four other unstable transformants contained 4 to 7% of human X-chromosomal DNA sequences. The transferred DNA was below the level of detection in three other unstable and in all three stable transformants. We conclude that the initial transfer event can introduce a substantial amount of genetic information but only smaller amounts of DNA are stably incorporated by integration.

Animals↗
PubMed1977

Serial transfer of a human gene to rodent cells by sequential chromosome-mediated gene transfer.

The human hypoxanthine phosphoribosyl-transferase (IMP:pyrophosphate phosphoribosyltransferase, EC 2.4.2.8) 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 selective medium. Metaphase chromosomes isolated from two of these clonal lines were incubated with Chinese hamster fibroblasts deficient in hypoxanthine phosphoribosyltransferase; five resulting independent colonies again expressed the human species of this gene. The transfer frequencies in the two cycles of chromosome-mediated gene transfer were similar (about 10(-7)). These results indicate that the transferred human chromosome fragment is closely associated with the chromosomes of the mouse A9 cells and it is probably integrated into the chromosomal DNA of the recipient cell.

Animals↗
PubMed1976

Genetic analysis by chromosome-mediated gene transfer.

A general method is presented for stable transfer of genetic information to eukaryotic cells, utilizing metaphase chromosomes as the vehicle. Recent progress, current problems and large areas of uncertainty in this field are reviewed; particular consideration is given to frequency of transfer, size of the transgenome, evidence of cotransfer of linked genes and serial chromosome transfer. A reasonable model for chromosome transfer is considered with respect to the available information, and various descrepancies are noted. The utility of this method for fine structural mapping, cloning small regions of the eukaryotic genome and other potential applications are discussed.

Animals↗
PubMed1972

A reassessment of the course of evolution of wheat.

Chromosome pairing in hybrids involving Triticum aestivum and new accessions of T. speltoides, and in an amphiploid of these species, indicates that T. speltoides can no longer be considered to be the donor of the B genome of the polyploid wheats. This necessitates a reconsideration of the genome relationships and evolutionary processes that gave rise to cultivated wheats.

Journal Article↗
PubMedDate not supplied

Diphtheria toxin sensitivity in a monochromosomal hybrid containing human chromosome 5.

Among the mouse-human hybrids prepared in our laboratory one clone was found to contain only human chromosome 5 with an integrated selectable marker. This monochromosomal hybrid was used to investigate different aspects related to the toxicity of diphtheria toxin (DT). The hybrid was as sensitive to diphtheria toxin as the human donor cells. The protective effect of NH4Cl against diphtheria toxin could be demonstrated in the hybrid and also in the mouse and human cell lines. The reversal of the protective NH4Cl effect at acid pH also could be demonstrated in all three cell types. Incubation of cells with 125I-diphtheria toxin at 37 degrees C in the presence of methylamine showed a time-dependent increase in specific association in the human and the hybrid but not in the mouse cell line. The results obtained for the first time on a stable monochromosomal hybrid suggest that chromosome 5 is both necessary and sufficient for the expression of DT sensitivity.

Ammonium Chloride↗