Activation of two Cynops genes, fork head and sonic hedgehog, in animal cap explants

We have isolated cDNAs of sonic hedgehog (shh) and fork head from Cynops (Japanese newt) embryo. Their expression was investigated in relation to mesoderm induction by activin and basic fibroblast growth factor (bFGF). Different from these homologs in Xenopus, they are activated not only by activin but also by bFGF in animal cap explants, showing a difference of animal pole cells in responsiveness to bFGF between Cynops and Xenopus. We also investigated the involvement of fork head in shh activation. The expression of shh was activated in animal caps which overexpressed either of two Xenopus fork head homologs, pintallavis/XFD-1 or XFKH-1/XFD-1', indicating that fork head up-regulates the transcription of shh in Cynops embryo.