Fig. 1. Kinesin heavy chain (Khc) mutants block oskar mRNA localisation after the transcript has been released from the anterior cortex. Localisation of oskar mRNA (A-F) and Staufen protein (G,H) at stage 9 of oogenesis in wild-type and Khc mutant ovaries. In wild-type egg chambers, oskar mRNA (A,C,E) and Staufen protein (G) localise to the posterior pole of the oocyte and remain anchored there throughout oogenesis. This localisation is completely abolished in ovaries that are mutant for Khc, and both oskar mRNA and Staufen protein are detected at the anterior and throughout the anterior half of the oocyte (B,F,H). By contrast, oskar mRNA is found at the anterior cortex in barentsz (D). staufen and mago nashi mutants show an identical phenotype (I. M. P. and D. St J., unpublished). oskar mRNA in situ hybridisation was performed with an anti-DIG antibody coupled either to alkaline phosphatase (A-D) or to Cy3 (E,F). Anterior is towards the left, posterior towards the right.