Fig. 7. The effect of Exp mutations on the defecation cycle length in wild-type and clk-1 mutant backgrounds. The bars represent the mean of the mean cycle lengths of n animals that had each been scored for five consecutive defecation cycles; the error bars represent the standard deviation of the animal means (n>10 animals). (A) In a wild-type (N2) background, both dsc-1(qm133) and exp-1(sa6) significantly shorten the defecation cycle; unc-25(e156) and hlh-8(nr2061) significantly lengthen the cycle. All the Exp mutants show an oscillation in cycle length, with the cycles getting progressively shorter as the worm becomes increasingly constipated (Con), which eventually produces a forceful expulsion, and is then followed by one or two longer cycles. This phenotype is revealed by the variability of the cycle length in individual animals scored for five cycles. This can be expressed as a per animal standard deviation. The average per animal standard deviations are as follows: N2: 0.89, dsc-1: 1.90, exp-1: 3.43, unc-25: 3.92 and hlh-8: 11.68. (B) Of the four Exp mutants surveyed, only the dsc-1(qm133) mutation can significantly suppress the lengthened defecation cycle of clk-1(qm30) mutants. The asterisks indicate the data that are significantly different from N2 (A) or clk-1 (B). All significant differences detected were at a level of P<0.0001.