Fig. 3.

Knockdown of fam3b expands anterior tissues, and the phenotype is rescued by low amounts of rhFAM3B protein. Embryos were first injected with control MO (120 ng) or fam3b MOs (60 ng fam3b.l MO and 60 ng fam3b.s MO) at the one-cell stage and subsequently BSA or rhFAM3B protein (40 nL at 3 μM) were injected into the blastocoele cavity at blastula stage, as indicated in the panels. Embryos were cultured until tailbud stage for phenotypic analysis or neurula stage for WISH with the indicated neural markers. (A–D) fam3b knockdown leads to enlarged heads and shorter A–P axis, which was rescued by injection of rhFAM3B protein. Arrowhead in B indicates enlarged cement gland. (E–P) fam3b knockdown expands forebrain markers bf1 (E–H), forebrain–midbrain marker otx2 (I–L), and eye marker rx2a (M–P), a phenotype that was rescued by injection of rhFAM3B protein at low doses. Numbers of embryos analyzed were as follows: A, n = 85, 100%; B, n = 96, 92% with enlarged cement glands; C, n = 90, 100%; D, n = 113, 86%; E, n = 53, 100%; F, n = 55, 96%; G, n = 49, 95%; H, n = 60, 88%; I, n = 38, 100%; J, n = 43, 95%; K, n = 50, 96%; L, n = 46, 91%; M, n = 37, 100%; N, n = 47, 93%; O, n = 39, 94%; P, n = 43, 86%. (Scale bars for A–D and E–P indicate 500 μm.)