Optimization of ENU mutagenesis of Caenorhabditis elegans

Chemical mutagenesis of Caenorhabditis elegans has relied primarily on EMS to produce missense mutations. The drawback of EMS mutagenesis is that the molecular lesions are primarily G/C --> A/T transitions. ENU has been shown to produce a different spectrum of mutations, but its greater toxicity to C. elegans makes it a difficult mutagen to use. We describe here methods fo r minimizing ENU toxicity in C. elegans. Methods include preparing ENU stoc ks in absolute ethanol and storing stock solutions for not more than 2 week s at -20 degreesC. To maintain reasonable brood sizes of mutagenized animal s, mutagenic solutions should not exceed 1.0 mM ENU. We provide data which suggest ENU is degraded or altered to more toxic products in aqueous soluti on, but less so in solvents such as absolute ethanol. (C) 2001 Published by Elsevier Science B.V.