mRNA Poly(A)-tail Changes Specified by Deadenylation Broadly Reshape Translation in Drosophila Oocytes and Early Embryos

Because maturing oocytes and early embryos lack transcription, posttranscriptional regulatory processes must control their development. To better understand this control, we profiled translational efficiencies and poly(A)-tail lengths throughout Drosophila oocyte maturation and early embryonic development. The correspondence between translational-efficiency changes and tail-length changes indicated that tail-length changes broadly reshape translational activity until gastrulation, when this coupling disappears. Relative changes were largely retained in the absence of poly(A)-tail lengthening, which indicated that selective poly(A)-tail shortening primarily specifies the changes. Many translational changes depended on PAN GU and Smaug, and both acted primarily through tail-length changes. Our results also revealed tail-length–independent mechanisms of translational control that repressed translation regardless of tail-length changes during oocyte maturation, maintained translation despite tail-length shortening during oocyte maturation, and prevented detectable translation of bicoid and several other mRNAs before egg activation. In addition to these fundamental insights, our results provide valuable resources for future studies. 42 samples analyzed using RNA-seq, ribosome footprint profiling, and PAL-seq.