Mutations in the Caenohabditis elegans maternal-effect gene
clk-1 affect cellular, developmental, and behavioral timing. They result in a slowing of the cell cycle, embryonic and postembryonic development, reproduction, and aging, as well as of the defecation, swimming, and pharyngeal pumping cycles. Here, we analyze the defecation behavior in
clk-1 mutants, phenotypically and genetically. When wild-type worms are grown at 20 degrees and shifted to a new temperature, the defecation cycle length is significantly affected by that new temperature. In contrast. we find that when
clk-1 mutants are shifted, the defecation cycle length is unaffected by that new temperature. We carried out a screen for mutations that Suppress the slow defecation phenotype at 20 degrees and identified two distinct classes of genes, which we call dsc for defecation suppressor of
elk-1. Mutations in one class also restore the ability to react normally to changes in temperature, while mutations in the other class do not. Together. these results suggest that dk-1 is necessary for readjusting the defecation cycle length in response to changes in temperature. On the other hand, in the absence of
clk-1 activity, we observe temperature compensation, a mechanism that maintains a constant defecation period iii the face of changes in temperature.