ZYG-9 is required to maintain spindle pole integrity.

(A) Movie stills from Metaphase I-arrested (emb-30(RNAi)) oocytes expressing mCherry::tubulin and degron::GFP::ZYG-9 acutely treated with either vehicle (left) or 100μM auxin (right). Following vehicle treatment, the oocyte spindle maintains ZYG-9 on the spindle and remains bipolar throughout the timecourse (n = 4). Auxin treatment causes a rapid loss of ZYG-9 signal and a concurrent loss of spindle pole stability highlighted by the unfocusing and fragmentation of the spindle poles (n = 4). Bars = 5 μm. Timestamp = min:sec. (B) Movie stills from Metaphase I-arrested (emb-30(RNAi)) oocytes expressing mCherry::tubulin, degron::GFP::ZYG-9, and GFP::ASPM-1 to track acentrosomal poles. Stable bipolar spindles have clear, focused ASPM-1 foci on either side of the spindle in control oocytes (n = 4). Acute 100μM auxin treatment to deplete ZYG-9 causes a rapid unfocusing and fragmentation of ASPM-1 foci, confirming loss of spindle bipolarity (n = 5). Splayed microtubule bundles can be seen in the midspindle region (white arrows) and fragments of ASPM-1 can be seen dissociating from poles (yellow arrowheads). Note that the spindle in rows 5 and 6 rotates to an end-on orientation by the end of the timelapse. Bars = 5 μm. Timestamp = min:sec.