mei-41 is required for precocious anaphase in Drosophila females

This paper reports on a new role for mei-41 in cell cycle control during me iosis. This function is revealed by the requirement of mei-41 for the preco cious anaphase observed in crossover-defective mutants. Normally in Drosoph ila oocytes, tension on the meiotic spindle causes a metaphase I arrest. Th is tension results because crossovers, and the resulting chiasmata, hold ho mologs together that are being pulled by kinetochore microtobules toward op posite spindle poles. In the absence of tension, such as in a recombination -defective mutant, metaphase arrest is not observed and meiosis proceeds th rough the two divisions. Here we show that in some recombination-defective mutants, the precocious anaphase requires the mei-41 gene product, For exam ple, metaphase arrest is not observed in mei-218 mutants because of the sev ere reduction in crossing over. In mei-41 mei-218 double mutants, however, metaphase arrest was restored. The effect of mei-41 is dependent on double- strand break formation. Thus, in mutants that fail to initiate meiotic reco mbination the absence of mei-41 has no effect.