The Ty1 Retrotransposition Short-Term Test for Selective Detection of Carcinogenic Genotoxins

Long-term tests are bioassays for carcinogenicity using animals (mainly rats or mice) as testers. Targets of the carcinogenic action are either organs or the whole body of the tester animal studied by dissection and histochemical analysis. These bioassays are not suitable for the study of a large number of substances because they are time consuming, expensive, require special facilities and qualified personal. A full long-term assay is completed in an average period of two years which stimulated the development of medium-term bioassays (Ito et al. 1998). These assays determine formation of neoplasms in various tissues of rats or mice within a period of 12-18 months. However, the existence of thousands genotoxins with potential carcinogenic effect requires the application of much faster assays and short-term tests have been developed and widely used. According to the timeframe required to obtain results in an assay, the transgenic mouse systems are intermediate between long-term and short-term tests. Although designated as “short-term bioassays” (Tennant et al. 1995) results from these tests are obtained in 4-6 months. The modified genes of transgenic animals cause them to respond rapidly to carcinogens (Cannon et al. 1997). Transgenic mouse systems are statistically reliable in vivo assays and the positive results obtained in the tests are highly predictive of rodent carcinogenicity.