RIP-seq for Ddx3xb in zebrafish embryos

We show that liquid-liquid phase separation (LLPS)-mediated zebrafish Ddx3xb condensation facilitates MZT through promoting maternal mRNAs translation. Ddx3xb forms condensates via its N-terminal intrinsically disordered regions (IDRs), and the gradually increased ATP concentration after fertilization promotes its aggregation capability. Ddx3xb-deficiency decelerates the decay of maternal mRNAs and impedes zygotic genome activation, further leading to developmental defect. The phenotype in Ddx3xb-deficiency embryos can be efficiently rescued by condensed Ddx3xb, but not the Ddx3xb without LLPS ability. Mechanistically, the condensation of Ddx3xb is vital for its RNA helicase activity, which is critical for involved in promoting translation efficiency of maternal mRNAs through opening 5’ UTR structures during the MZT process. Our study demonstrates that the condensation of Ddx3xb promotes maternal mRNAs translation via its RNA unwinding activity and further facilitates MZT, highlighting the critical role of protein phase separation in translational control and animal early development. RIP-seq of 4 samples from Ddx3xb mRNA injected zebrafish embryos at 2 and 4 hpf including two biological replicates