The objective of this proposal is to evaluate a new system for generating mutants in C. elegans , and to utilize this system to generate mutants for genetic studies of embryonic differentiation pathways. The mutagenesis system is based on light.catalyzed DNA crosslinking by trimethylpsolaren, and is thought to be biased toward modification of genes being actively transcribed. This hypothesis will be tested in experiments designed to generate lethal mutations in genes which are activated during early embryogenesis. Mutations generated in Linkage group II by this approach will be isolated, and characterized in comparison to known mutations generated by the action of ethylmethane sulfate. Studies on the phenotypes of the most promising mutants will also be initiated. Possible bias toward active genes will be analyzed by the effects of trimethylpsolaren applied at defined times during embryogenesis. This research, which is highly exploratory in nature, has the potential to provide a new, generally useful experimental system for the generation and analysis of developmental mutations.
