Generation and Study of Zebrafish Genomic Instability Mutants

9604923 Cheng Genomic instability causes genetic changes including chromosome loss, translocation, recombination and point mutations and plays an important role in genetic diversity and evolution. The long-term goal of the proposed work is to elucidate the molecular mechanisms that control genomic stability in vertebrates. A unique screen, developed in this laboratory, creates an opportunity to render heterozygous mutations homozygous in one step using parthenogenesis in the zebrafish. A screen for genetic instability mutants (gin) is based upon the detection of abnormally high rates of somatic loss of heterozygosity (LOH). The screen allows frequencies of LOH as low as 10-5 to be detected. Mutagenesis of male zebrafish with ethylnitrosourea has resulted in 1-2 mutations per average gene per 1000 haploid genomes. One gin mutant has been identified and will be characterized, as will other such mutants as they are isolated, by Mendelian inheritance, complementation testing, quantitation of the effect of mutations and genetic mapping. Genomic instability mutants in unicellular organisms gave the first significant insights into the mechanisms of mutation. However, until now, such studies have not been possible in vertebrates. It is now possible to identify new genes that may be specific to vertebrates. The information to be gained from this study may enhance our understanding of the fundamental mechanisms involved in genetic mechanisms operative in vertebrates and also contribute to an understanding of some genetic diseases.