[
Methods Mol Biol,
2013]
The principle of commonly used methods to create mutations in the nematode Caenorhabditis elegans (C. elegans) is straightforward. In general, worms are exposed to a dose of mutagen resulting in DNA damages and mutations. Screening the progeny of the mutagenized animals for a certain phenotype is the regular forward genetic approach in C. elegans. A mutant selected from such a population is stabilized to recover a pure homozygous strain. In this chapter, we categorize the protocol into mutagenesis, phenotype screen, and outcross and provide time-tested procedures for their implementation to create long-lived worm mutants.
[
1987]
Work in our laboratory over the past several years has focused on the nature of early determinative decisions in embryos of the free-living nematode Caenorhabditis elegans. Two of these decisions regard determination of sex and determination of the level of X-chromosome expression. C. elegans has two sexes, self-fertilizing hermaphrodites and males. Hermaphrodites normally have two X chromosomes, and males have only one (there is no Y chromosome). Genetic and molecular evidence suggest that C. elegans compensates for this difference in X dosage, not by X inactivation as in mammals, but rather by global regulation of the X chromosome as in Drosophila; that is, X-linked genes are expressed at a higher level per chromosome in 1X than 2X animals, so that levels of X expression are similar in the two sexes. Also as in Drosophila, the primary signal that dictates both sex determination and level of X expression in C. elegans is the ration of the number of X chromosomes to the number of sets of autosomes (X/A ratio) rather than the absolute number of X chromosomes.|