Practice question

Dishevelled protein required for vegetal beta-catenin stabilization shows precise temporal localization pattern. Maternal Dishevelled protein and mRNA are deposited and anchored to vegetal cortex during oogenesis, well before fertilization occurs, through actin and microtubule dependent transport mechanisms. In full-grown oocytes, in situ hybridization and immunostaining reveal vegetal cortical enrichment. Fertilization does not induce this localization; it is inherited from oogenesis. This pre-fertilization placement ensures that by fourth cleavage, micromeres inherit high Dishevelled and therefore high nuclear beta-catenin, permitting autonomous specification. Relocalization after fertilization cannot fully rescue patterning, indicating temporal requirement.