Figure 1. Differential association of bcd and grk with P bodies.

(a-d) mRNA detection at the dorsoanterior corner (for orientation, see Fig. 2a) by ISH-IEM on wild-type (WT) ultra-thin frozen sections of stage 9 oocytes. (a) bcd mRNA (5nm, green circles) is present both inside and at the edge of electron dense P bodies (dashed black line). Gold particles here cluster due to the use of a bridging antibody. (b) grk mRNA (15nm, red circles) is enriched at the edge of P bodies (dashed black line). (c) bcd mRNA (5nm, green circles) and grk mRNA (15nm, red circles) can associate with the same P body but bcd is enriched inside. (d) grk mRNA (15nm, red circles) docks at the edge of the P body (black dashed box magnified, inset bottom right), just outside of the Me31B dense core region (5nm gold), while grk transport particles, as described in Delanoue et. al., 2007⁽⁷⁾, are detected in the cytoplasm at a short distance from the P body (15nm, red dashed circles). (e) mRNA density (gold/um²) in the P body sub-regions when compared to the surrounding cytoplasm. For comparison, randomized particles were analyzed in an identical way to RNAs. Error bars show SEM of gold density per scan (grk n=13, bcd n=11). (f,g) Fixed Me31B::GFP stage 8/9 expressing oocytes imaged using the OMX structured illumination super-resolution mode (3D-SIM) with double labeling of either (f) grk*mCherry, that mainly interdigitates with Me31B (green) while showing some colocalization at the edge (yellow) or (g) bcd*RFP grk mRNA (red), that shows significant colocalization (yellow) with Me31B (green). Scale bars, 200nm (a-d); 0.5μm (f, g).