(A) In situ hybridizations of early zygotic genes in 16-cell Ciona embryos injected with either in vitro transcribed GFP:H2B control mRNA, Ccnb3 mRNA, Ccnb3 mRNA with mutations in the cdk binding domain (Ccnb3 AAA mRNA) or Ccnb1 mRNA. Ccnb3 overexpression resulted in the failure to detect any expression of early zygotic genes and a loss of cell adhesion.
(B) In situ hybridizations of 16 cell embryos for Foxa.a where one blastomere at the 2-cell stage was injected with Ccnb3 mRNA. Cells that have reduced staining are indicated with a green arrowhead. Embryos are mounted anterior up. For Foxa.a and Tfap2-r.b stainings, the embryo is oriented to show the animal hemisphere and for Foxd.b and Tbx6-r.b stainings, the embryo is oriented to show the vegetal hemisphere. Scale bar = 50 µm. See also Figure S3.