Cas9-mediated excision of disrupts endoderm development, pharynx formation and oral-aboral patterning.

The mesoderm is a key novelty in animal evolution, although we understand little of how the mesoderm arose. , the founding member of the T-box gene family, is a key gene in chordate mesoderm development. However, the gene was present in the common ancestor of fungi and animals long before mesoderm appeared.

Expression of a lung developmental cassette in the adult and developing zebrafish swimbladder.

The presence of an air-filled organ (AO), either lungs or a swimbladder, is a defining character of the Osteichthyes (bony vertebrates, including tetrapods). Despite the functional and structural diversity of AOs, it was not previously known whether the same group of developmental regulatory genes are involved in the early development of both lungs and swimbladders. This study demonstrates that a suite of genes (Nkx2.