ANALYSIS OF RADIATION-INDUCED CHROMOSOME-ABERRATIONS IN CHINESE-HAMSTER CELLS BY FISH USING CHROMOSOME-SPECIFIC DNA LIBRARIES

The frequencies of chromosome aberrations induced by different doses o f X-rays were determined in both splenocytes and primary lung fibrobla sts of Chinese hamster by bi-colour FISH using a combination of four c hromosome-specific DNA libraries. The results indicate that the X-rays induced more translocations than dicentrics in Chinese hamster cells, in which the karyotype is comprised of both metacentric and acrocentr ic chromosomes. These results are similar to those reported in human l ymphocytes, in which the karyotype contains many metacentric chromosom es. On the contrary, in mouse, which is characterized by acrocentric c hromosomes only, the frequencies of translocations and dicentrics are induced in nearly equal proportions by X-rays. The ratio of translocat ions to dicentrics obtained in Chinese hamster cells was approximately 1.4-1.5, which supports the importance of the karyotypic features of a species in the relative induction of translocations to dicentrics. A n analysis was also made on the yield of translocations and dicentrics involving individual chromosomes and the results indicate a non-rando m involvement of these chromosomes in the formation of aberrations.