Bcat overexpression - Axis duplication - Wnt activity - dorsal lip of blastoporus - gastrulation - symmetry - two spots for wnt - two heads - fish not mammals - mouse - anterior - low bcat signaling - posterior - high - ventral side : NODE - "organizer" - -> mammal axis duplication: caudal duplication- two bottoms - axin= axis inhibitor - Axis1 mutation in homozyg twins - only one with duplication phenotype . Role of methylation Teeth - wnt signaling GOF/LOF have different effects at different times during development