Borrowing thy neighbour's genetics: Neural induction and a Brachyury mutant in Xenopus

A recent article by Rao⁽¹⁾ exemplifies a number of new trends in developmental biology, both of technical strategy and approach to the problem of neural induction. Rao introduced into frog embryos a mutant form of a mesodermal gene, Brachyury, and caused ectopic neural differentiation. This essay traces the route from the original Brachyury mutation in mouse to the most likely conclusion of Rao's experiments — suggested previously⁽²⁾ — that neural fate is a default pathway.