The movement of Staufen-SunTag in streaming oocytes. (A) A cartoon of SunTag labeling of Staufen. The Staufen-SunTag contains two components: (1) 24 copies of GCN4 epitope fused to the C terminus of Staufen and (2) an anti-GCN4 single-chain variable fragment (scFv) tagged with sfGFP and a nuclear localization signal (NLS). SunTagging attaches 24 copies of GFP to the Staufen C-terminal tail; free GFP-fused antibody is sequestered in the nucleus. (B–B’’) Staufen-SunTag labeling particles all contains osk mRNA. Staufen-SunTag and osk mRNA were colocalized both at the posterior crescent and in individual cytoplasmic particles (arrowheads). (C) Average velocities (mean ± 95% confidence intervals) of Staufen-SunTag particles in the cytoplasmic area, lateral cortex, and posterior cortex (outlined boxes). Unpaired t test with Welch's correction between the following groups: cytoplasmic area and lateral cortex, P < 0.0001; cytoplasmic area and posterior cortex, P < 0.0001; lateral cortex and posterior cortex, P < 0.0001. (D) Kymographs and velocities (mean ± 95% confidence intervals) of yolk granules at lateral cortex and posterior cortex of control oocytes. (E and F) Kymographs and average velocity (mean ± 95% confidence intervals) of Staufen-SunTag particles at different distances from the posterior cortex and the lateral cortex. Bars: 50 µm (main images); 10 µm (insets).