Top left: Slbo in the outer border cell non- cell autonomously regulates JNK signaling to maintain the proper apical–basal polarity of the migrating border cell cluster. The proper polarity of the border cell cluster facilitates the formation of the polar cell protrusion at stage 13. Bottom left: After formation of the polar cell protrusion, JNK signaling in the polar cell regulates the movement of lysosomal components towards the oocyte through the nanotube. is deposited at the tip of the protrusion which aids to open the vitelline envelope for sperm entry during fertilization. Right: High-resolution 2D STED imaging (30 nm XY resolution) of a Stage 13 Drosophila egg chamber reveals lysosomal dynamics within a polar-cell nanotube. The polar-cell protrusion is labelled with Fas III (Magenta), nuclei are stained with DAPI (Blue), and lysosomal compartments are visualized using LAMP1-eGFP (Green), which are enriched at the apical side of the polar cell and are also present within the protrusion, indicating active trafficking through the nanotube. Images were acquired with a 60× objective on an ABBERIOR 3D-STED Facility Line microscope.
Membrane #nanotubes are cytoskeletal structures that facilitate intercellular communication. This study shows that polar cell-derived #microtubule nanotubes play a role in #Drosophila #fertilization, creating a channel in the eggshell that facilitates #sperm entry @plosbiology.org 🧪 plos.io/3XwOlvS