In Drosophila, the establishment of the anteroposterior (AP) axis occurs during oogenesis and is determined by the localisation of bicoid and oskar mRNA to the anterior and posterior of the oocyte, respectively, via microtubule cytoskeleton polarisation. To uncover additional genes involved in this process, Martin et al. performed an elegant genetic screen that, unlike previous genetic screens of AP axis determination,permits the recovery of lethal mutations (see ). By identifying, in living oocytes, chemical-induced mutations that disrupt the localisation of GFPStaufen in germline clones (because Staufen binds to both bicoid and oskar mRNA, GFP-Staufen is a marker for both poles of the oocyte at different developmental times), Martin et al. discovered 23 new complementation groups on chromosome 3R that disrupt AP axis formation. As a forerunner of what their results could eventually reveal about AP axis formation, the authors' characterisation of several mutations reported here indicate their involvement in microtubule organisation.
