Remnants of the Balbiani body are required for formation of RNA transport granules inXenopusoocytes

Fragmentation of the Balbiani body in Xenopus oocytes engenders a region extending from the germinal vesicle (GV) towards the vegetal pole that is enriched in mitochondria. This area is later transversed by RNA that is being localized to the vegetal cortex. Inhibition of mitochondrial ATP synthesis prevents the perinuclear formation of these RNA transport granules that can be reversed by the nonhydrolyzable ATP analog, adenosine 5’-(βγ-imido) triphosphate. The protein composition and sensitivity of the transport granules to hexanediol indicate that they are liquid phase condensates. Mitochondria in the remnants of the Balbiani body produce a region of elevated ATP that appears to act as a hydrotrope to support the perinuclear phase transition leading to granule formation. Summary Mitochondria in the remnants of the Balbiani body produce elevated levels of ATP required for the formation of liquid phase condensates containing RNA transport granules.