FERTILIZATION OF XENOPUS EGGS IMPOSES A COMPLETE TRANSLATIONAL ARRESTOF MESSENGER-RNAS CONTAINING 3'UUAUUUAU ELEMENTS

The early embryonic development of Xenopus is mainly governed by post- transcriptional regulations until the mid-blastula transition. In this report, we present evidence demonstrating that fertilization of Xenop us eggs triggers a complete translational arrest of mRNAs containing U A-rich elements in their 3'-untranslated region. This control is maint ained at least until the mid-blastula transition. Neither maturation n or pseudo-fertilization of the egg is sufficient for triggering this c ontrol, suggesting that components originating from the male gamete ar e involved in the mechanism. Moreover, this control is exerted whether the mRNA is polyadenylated or not.