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ANALYSIS OF X-RAY INDUCED HPRT MUTATIONS IN CHO CELLS: INSERTION AND DELETIONS
Citation:
Fuscoe, J.C., L. Zimmerman, A. Fekete, AND B. Rossiter. ANALYSIS OF X-RAY INDUCED HPRT MUTATIONS IN CHO CELLS: INSERTION AND DELETIONS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-92/437 (NTIS PB93141364), 1992.
Description:
Molecular alterations were examined in the hypoxanthine guanine phosphoribosyltransferase (hprt) gene of 41 independent X-ray-induced thioguanine-resistant (TGR) Chinese hamster ovary (CHO) cell clones. Rapid screening of the clones by multiplex polymerase chain reaction (PCR) for the presence or absence of exons revealed that the bases for the mutant phenotype were total gene deletion (26/41), partial gene deletion (4/41), and an insertion (1/41). o alterations of exon number or sites were apparent in 10 of the mutants. outhern blot analysis confirmed the deletion data and revealed an additional class of mutants that had a gene disruption but retained all hprt exons (2/41). Therefore, at least 80% of the ionizing radiation-induced mutations were due to mechanisms involving DNA breakage and rejoining. he distribution of deletion sized suggests that the two DNA breaks rehired for a deletion are not independent events. ossible mechanism is presented. n addition, the DNA sequence of the insertion mutation was determined. The insertion (229bp) is coupled with a deletion (31bp). n imperfect inverted repeat with flanking hprt DNA was identified and may be involved