Application of a wheat seedling assay for detecting aneuploidy induced by N-ethyl-N-nitrosourea and 4-nitroquinoline-1-oxide

Loss of heterozygosity in Phytophthora capsici after N-ethyl-nitrosourea mutagenesis

Loss of heterozygosity (LOH) occurs in a variety of diploid organisms after chemical mutagenesis and was observed in the vegetable pathogen Phytophthora capsici after N-ethyl-nitrosourea (ENU) mutagenesis at three loci during reverse genetic screening. Our objectives were to determine (i) the frequency of LOH among mutants, (ii) the directionality of the LOH events and (iii) the length of the genomic tracts exhibiting LOH. Of the 1152 ENU mutants screened, LOH was most frequent at locus 3 (99 ENU mutants), with locus 1 (10 ENU mutants) and locus 2 (9 ENU mutants) undergoing LOH at similar frequencies. LOH was bidirectional for all three loci, with locus 3 mutants biased toward one haplotype. Analysis of upstream and downstream heterozygosity indicates that the LOH events spanned up to at least 4.6 kb. The implications of mitotic recombination and LOH for reverse genetics and natural variation in Phytophthora are discussed.

Epithelial and fibroblast cell lines cultured from the transgenic BigBlue rat: an in vitro mutagenesis assay

We have isolated, cultured, and immortalised three new BigBlue transgenic rat cell lines for the study of mutation induction in vitro. The two epithelial cell lines, from the mammary gland and oral cavity, were designated BBR/ME and BBR/OE, respectively, and the third is a mammary fibroblast line designated BBR/MFib. We have characterised these cell lines with respect to chromosome number and the expression of some cell-specific antigens. The clonogenic survival and cII transgene mutation induction responses of these three cell lines to N-ethyl-N-nitrosourea (ENU) treatment were determined. Both epithelial cell lines were much more sensitive to ENU toxicity than was the fibroblast cell line. However, all cell lines showed similar ENU dose-dependent increases in mutant frequency. We hope that cell lines such as these will extend the power of the BigBlue assay to in vitro studies.

Higher plant assays for the detection of chromosomal aberrations and gene mutations-a brief historical background on their use for screening and monitoring environmental chemicals

Higher plants are recognized as excellent indicators of cytogenetic and mutagenic effects of environmental chemicals and are applicable for the detection of environmental mutagens both indoor and outdoor. They are highly reliable bioassays with a high sensitivity for monitoring and testing for genotoxins. A brief review of major steps in the development of higher plant genotoxic assays is given.