Key-notes on Neural Induction

1.2. Genetic redundancy

The BMP patterning system that underlies neural induction in vertebrates is notable for extensive redundancy in gene function that has made a loss-of-function approach problematic: mutations that eliminate only one of these inhibitors tend to have relatively mild phenotypes on their own. For example, a loss-of-function mutation in Zebrafish chordin (the chordino mutant) causes only a reduction in the size of the neural plate while mouse embryos that lack just one the BMP antagonists, chordin or noggin, by knockout mutations have a relatively normal nervous system. However, the full potential of these antagonists became apparent when several of them are removed at the same time. A complete loss of neural tissue is observed when all three BMP antagonists, chordin, follistatin and noggin, are simultaneously targeted using morpholinos, both in Xenopus and in Zebrafish.