<i>hox</i> gene expression predicts tetrapod-like axial regionalization in the skate, <i>Leucoraja erinacea</i>
Katharine E. Criswell, Lucy E. Roberts, Eve T. Koo, Jason J. Head, J. Andrew Gillis
Abstract
Significance The tetrapod vertebral skeleton is subdivided into distinct regions that are determined by spatial expression of Hox genes in the early embryo. Fishes are thought to lack comparable regionalization, but the relationship between anatomy and hox expression has not been tested beyond tetrapods. By comparing vertebral morphology with embryonic hox expression in a cartilaginous fish, the skate ( Leucoraja erinacea ), we found that the skate vertebral column is regionalized, with regional transitions predicted by embryonic hox gene expression patterns. This discovery points to an origin of nested hox gene expression and hox -based vertebral regionalization at the common ancestor of jawed vertebrates.