Figure 5.—

Monopolar mitosis in APC/C mutants substantially increases M phase duration. Bars represent average M phase duration in one-cell–stage embryos of the indicated genotypes measured from the beginning of NEBD until NER in DIC time-lapse recordings. N = number of embryos. Error bars, standard error of mean. (A) such-1(t1668) class I and class II embryos with a bipolar spindle are delayed only slightly during M phase, while class III embryos are delayed sevenfold. (B) Monopolar mitosis in APC/C mutants substantially increases M phase duration. Note that all mutant embryos are delayed upon spd-5(RNAi). (C) Ubiquitination influences M phase duration in monopolar mitosis. Albeit partial RNAi of uba-1 [in addition to spd-5(or213)] provokes a modest increase in M phase duration, the difference with partial uba-1(RNAi) alone is statistically significant (paired Student's T-test; P = 1.9 × 10⁻⁵). (D) Partial reduction of FZY-1 function by partial RNAi or with fzy-1(h1983) provokes a modest but statistically significant increase in M phase duration in embryos with a monopolar spindle induced by SPD-5 depletion (paired Student's T-test compared to fzy-1(RNAi) P = 1.4 × 10⁻⁴; fzy-1(h1983) P = 3.7 × 10⁻⁵). fzy-1(av15) rescues M phase duration in conditions that normally cause a drastic delay (compare to B).