Net minus end–directed transport of apically localizing transcripts requires Lis1. (A) Fluorescent immunoblot showing equivalent levels of Egl, BicD, and Dhc between WT and lis1 mutant ovaries. Comparison of the fluorescence intensity in Lis1 blots reveals that Lis1 levels in the heterozygous and trans-heterozygous genotype are ∼65% and ∼25% of WT, respectively (for quantification see Fig. S2 A). (B) Immunostaining of MTs (α-tubulin, red) and centrosomes (α-centrosomin, green) in cycle 14 blastoderm embryos from WT and lis1^E415/lis1^k11702 mutant mothers, revealing that centrosome position and MT organization and length are not perturbed by reduced Lis1 levels. Nuclei, blue (DAPI). Ap, apical; Ba, basal. (C) Still images from time-lapse movies of injected Alexa Fluor 488–labeled h RNA, revealing a strong defect in apical transport in embryos from lis1^E415/lis1^k11702 mothers compared with WT (see corresponding Video 4). Red and yellow arrows mark injection site and apically localized RNA, respectively. Time after injection is shown. (D–I) Motile properties of h (D–F) and asK10 (G–I) RNA particles after injection into the stated maternal genotypes. In D–F, +TG indicates the presence of two copies of a weakly expressed lis1 transgene. See Table S2 for full details of motile properties and number of particle tracks analyzed. *, P < 0.05; **, P < 0.01; ***, P < 0.001 (ANOVA test). Error bars represent SEM. Bars: (B and C) 10 µm.