Evolution of the back-to-belly axis

Early in our embryogenesis, the two main body axes (head-tail and back-to-belly axis) are established to provide positional cues through a coordinate system for the differentiating cells. In a new publication in the journal Cell Reports the team of developmental biologist Ulrich Technau from the University of Vienna has now found evidence for an ancient origin of the back-to-belly axis in a sea anemone. The signaling system that is responsible for the establishment of this axis was already present in the common ancestor of sea anemones and humans, at least 600 million years ago. However, the sea anemone does not use the system for specifying the dorso-ventral axis, but for their own specific axis and structures. Most animals have a dorso-ventral (back-to-belly) body axis, which determines for instance the localized position of the central nervous system, dorsal in humans, ventral in insects. Surprisingly, despite enormous morphological differences, the same signaling molecules of Bone morphogenetic protein (BMP) molecules establishes the dorso-ventral axis including the central nervous system in both insects and vertebrates, which led to the conclusion that this molecular mechanism was already present in the common ancestor. How deep can we trace the origin of the dorso-ventral axis? It turned out that sea anemones provides the answer: "By analysing the role of BMPs during embryogenesis of the sea anemone Nematostella vectensis, we could get insights into the evolution of animal body axes." says Ulrich Technau of the Department of Molecular Evolution and Development at the University of Vienna. Two body axes in the sea anemone