Figure 1.

The CPC is mislocalized in polo mutant meiosis I. In wild-type spermatocytes the CPC concentrates at the centromeres in prometaphase I (a) and metaphase I (b). In all polo mutant combinations, we observe differences in the CPC localization in spermatocytes. The different phenotypic categories observed are shown in (c–f). These phenotypes range from normal localization (c), slight dispersion to surrounding heterochromatin (d), diffuse localization all over the chromatin (e) or reduction/absence of CPC signal (f). Green, α-tubulin; red, INCENP; blue, DNA; scale bars, 1 µm. (g) Predicted effect of the polo¹ mutation on kinase function. Left, structure of human Plk1 kinase domain (PDB code 2OWB). Arrowhead points to the T-loop; arrow points to the residue mutated in polo¹ (valine 242). Right, surface view of the kinase domain. Long arrow points to substrate-binding groove, formed by subdomains VIII and IX. (h) Quantification of the percentages of each phenotypic category (as shown in c–f) in the different polo mutant allelic combinations studied.