Movie 1.

Incubation with VitelloTag:Cas9 RNPs produce zygotic loss-of-function phenotypes in S. kowalevskii. In comparison to control oocytes treated with VitelloTag:Cas9 alone (left), oocytes treated with VitelloTag:Cas9 and gRNAs against beta-catenin (right) have an anteriorized phenotype, but gastrulate successfully and have a small posterior domain (evident by the small ciliary band), which is consistent with zygotic loss of function. For reference, embryos injected with siRNAs against beta-catenin to deplete maternal transcripts (Darras et al., 2011) are fully animalized and do not gastrulate or produce endomesoderm or posterior ectoderm. For both embryos shown, anterior is at left, and dorsal is at top.