抄録
Radiation exposure causes genetic instability in mammalian cells while the underlying mechanisms are not well understood. Although most of the animal studies used repeat sequences as the target for detection of the instability (e.g., minisatellites and pink eye-unstable locus), no pertinent assay systems are available in cultured cells. We therefore thought it useful to create cultured cells bearing partial, tandem duplication of a gene. We have chosen HPRT gene as a model since the duplication makes the cells HPRT(-) and hence selectable in the presence of 6TG, and HPRT(+) revertants due to intragenic recombination of the duplicated sequences in HAT medium. We constructed a Neo-tagged vector carrying 8.4kb genomic DNA that covers HPRT exons 2-3. Transfection of human fibrosarcoma cells (HT1080) with the vector yielded Neo-resistant and 6TG-resistant clones. These cells reverted spontaneously from HPRT(-) to HPRT(+) with relatively high frequencies as expected [i.e., 10(-5) to 10(-4)]. Preliminary results will be presented on the relation between the reversion and forward mutation frequencies at the HPRT gene of some clones. [J Radiat Res 44:442 (2003)]
