Posterior pole of dermapteran oocytes houses a single aggregate of organelles reminiscent of endolysosomal vesicular assemblies described in mouse oocytes

Abstract

Oocytes of derived dermapterans (the Eudermaptera), in addition to “conventional” organelles, i.e. mitochondria, elements of endoplasmic reticulum, Golgi complexes, lysosome-like bodies and reserve materials (yolk spheres, lipid droplets), contain unexpectedly rich set of noncanonical organelles. It includes assemblies of endoplasmic reticulum and fine granular “nuage” material, ribosome-associated vesicles, and extensive arrays of parallel arranged endoplasmic reticulum cisternae. During vitellogenesis (yolk formation), all lysosome-like bodies are gradually translocated towards the posterior oocyte pole, where they form relatively large, morphologically distinct compartment that we termed the posterior pole lysosomal compartment. This compartment is not surrounded by a limiting membrane and stains positively with Proteostat, a dye used to detect proteins implicated in the formation of biomolecular condensates. In the light of these results, we hypothesize that posterior pole lysosomal compartment is reminiscent of endolysosomal vesicular assembly/ies participating in the sequestration/degradation of aggregated proteins in mammalian oocytes.