ABOVE: An image of dissected zebrafish pectoral fin bones demonstrates that fish with a gain-of-function mutation in waslb have two more long bones (right, arrowheads) than wildtype fish (left).
M.B. HAWKINS ET AL., CELL, 2021
While the differences in form and function between the fins of fish and the jointed forearms of those of us with four limbs are quite obvious, there’s a common link: both descend from the same appendage borne by our shared ancestor, a bony fish. In a study published today in Cell, researchers identify a gain-of-function mutant in the zebrafish (Danio rerio) that grows an extra set of bones at the ends of two long bones in the fin. The genetic program that makes the extra bones is similar to the instructions for forearm bones in tetrapods.
“There is this latent potential to build morphological structures in lineages where you think these structures have long been gone,” ...
