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Figure S1. CV2 mRNA Is Expressed in Regions of High BMP and Its Depletion Ventralizes Xenopus Embryos. The expression pattern of CV2 in Xenopus embryos has not been previously reported. CV2 was expressed in all three embryonic layers, ectoderm, mesoderm, and endoderm in domains overlapping with those of BMP4 expression [Fainsod, A, Steinbeisser, H., and De Robertis, E.M. (1994). EMBO J. 13, 5015-5025]. At later stages, CV2 expression was detected in other regions of high BMP signaling such as the dorsal region of the eye and the cement gland, the roof plate, the hypochord, and blood islands. Before gastrulation, CV2 transcripts were undetectable by in situ hybridization or RT-PCR. (A) In a hemisected mid-gastrula stage embryo, CV2 is expressed in broadly in ventral regions. Bracket marks the blastopore. (B) At late gastrula, CV2 expression concentrates around the ventral blastopore. (C) In a neurula stage hemisected embryo, CV2 expression is seen in the ventral endoderm around the blastopore marked by bracket. (D) CV2 expression is turned on in the dorsal eye, the cement gland and is still present in the ventral endoderm in hemisected tadpoles. (E) CV2 is expressed in high BMP regions both in the ventral and the dorsal side of transversely sectioned embryos. Inset shows CV2 expressed in the roof plate of the spinal cord and in the hypochord. (F) RT-PCR analysis indicates CV2 expression is zygotic, starts at gastrula, and reaches its maximum at neurula stage. (G) Stage 32 uninjected embryo (inset shows stage 40). (H) The CV2MO injected embryo shows a reduced head and dorsal (white arrow) and ventral fins and a strikingly smaller eye (inset). (I) Uninjected embryo stained with eye marker Six3 and the ventral BMP signaling marker Sizzled. (J) CV2 depletion reduces the eye marker Six3 and increases ventral BMP signaling marked by Sizzled. bc, blastocoele; vb, ventral blastopore; ve, ventral endoderm; ar, archenteron; ey, eye; cg, cement gland; bi, blood island; rp, roof plate; sc, spinal cord; no, notochord; hy, hypochord |
