Fig. 6

Sqt and Cyc in the YSL are required for endoderm and head mesoderm. Embryos were injected with sqt and cyc mismatch MOs (A, C, E, G, I, K) or sqt and cyc MOs (B, D, F, H, J, L) and processed for in situ hybridization for mesoderm and endoderm marker genes. Control MOs do not affect expression of gsc (A), flh (C), mezzo (E), sox17 (G), sqt (I) or cyc (K). (B) By contrast, gsc expression is eliminated when sqt and cyc MOs are co-injected into the YSL. (D) flh expression is reduced, but not eliminated in these embryos. (F) These embryos also completely lack mezzo expression. (H) sox17 expression is eliminated from the endoderm progenitors, but not from the dorsal forerunners. (J) Extremely low levels of sqt expression are apparent when Sqt and Cyc signals are depleted from the YSL. (L) cyc expression is greatly reduced, except for a small patch of expression in the presumed dorsal blastomeres. In panels A–D, E–F, I–L, dorsal is to the right, when apparent.