Fig 6. Panda plays a pivotal role during D/V axis formation.

(A) Morphological phenotypes resulting from injection into the egg of antisense morpholino oligonucleotide targeting the translation start site of the panda transcript. Down-regulation of panda completely radializes the embryos during the first 48 h, but a partial recovery of D/V polarity occurs afterwards, as evidenced by the formation of a short dorsal apex. This phenotype is similar to that caused by treatments with recombinant Nodal protein at 1 μg/ml. (B) In situ hybridization on control embryos and panda morphants at the blastula and gastrula stages with ventral, ciliary band, and dorsal marker genes. Note the dramatic ectopic expression of nodal, chordin, and foxA at the blastula stage in panda morphants. At the late gastrula stage, despite their radialized morphology, panda morphants are patterned along the D/V axis, as evidenced by the restricted expression of nodal, foxA, foxG, onecut, and hox7. Note, however, the extended expression of these ventral markers compared to control embryos. (C) A second morpholino oligonucleotide targeting the 5' UTR of the panda transcript produces similar phenotypes and radializes the expression of nodal and chordin. (D) Scheme describing the changes in fate maps caused by the single inactivation of panda or bmp2/4 or by the double inactivation of panda and bmp2/4. LV, lateral view; VV, vegetal pole view; AV, animal pole view; V, ventral; D, dorsal.