FIG 6.

Interactions of Vgs with Nasuia porins of different leafhopper species. (A) Localization of Vg and Nasuia in the epithelial plugs or the oocytes of the leafhopper N. nigropictus, N. virescens, or R. dorsalis. The female ovaries were stained with Nasuia-cy3 (red) and Vg2-FITC (green). Bars in the leftmost insect image panels,  1 mm. Bars in the rightmost immunofluorescence image panels, 50 μm. (B) Interactions between the second domains of Vgs and Nasuia porins of the three leafhopper species in the yeast two-hybrid system. DDO, SD-Trp-Leu; QDO, SD-Trp-Leu-His-Ade. (C) Proposed model for the two oocyte entry paths of Vg into insect oocytes. Vgs were synthesized in the fat body and then were processed and cleaved into two subunits, the small subunit (Vg-S, 35 kDa) and the large subunit (Vg-L, 178 kDa) in the hemolymph, and finally, Vg-L was able to enter the developing oocytes via the gemarium entry path or enter the posterior pole of the terminal oocyte via hitchhiking Nasuia. ET, egg tube; NC, nurse cell; TF, terminal filament; TC, trophic core; Fc, follicular cell; Gr, germarium; Ep, epithelial plug; Nc, nutritive cord; O, oocyte; Pd, pedicel; Sb, symbiont ball. All images are representative of at least three replicates.