MUTATIONS IN THE CLK-1 GENE OF CAENORHABDITIS-ELEGANS AFFECT DEVELOPMENTAL AND BEHAVIORAL TIMING

We have identified three allelic, maternal-effect mutations that affec t developmental and behavioral timing in Caenorhabditis elegans. They result in a mean lengthening of embryonic and postembryonic developmen t, the cell cycle period and life span, as well as the periods of the defecation, swimming and pumping cycles. These mutants also display a number of additional phenotypes related to timing. For example, the va riability in the length of embryonic development is several times larg er in the mutants than in the wild type, resulting in the occasional p roduction of mutant embryos developing more rapidly than the most rapi dly developing wild-type embryos. In addition, the duration of embryon ic development of the mutants, but not of the wild type, depends on th e temperature at which their parents were raised. Finally, individual variations in the severity of distinct mutant phenotypes are correlate d in a counterintuitive way. For example, the animals with the shortes t embryonic development have the longest defecation cycle and those wi th the longest embryonic development have the shortest defecation cycl e. Most of the features affected by these mutations are believed to be controlled by biological clocks, and we therefore call the gene defin ed by these mutations clk-1, for ''abnormal function of biological clo cks.''