BACKGROUND Classic embryological studies showed that diffusible factors (morphogens)
influence cell fate during dorsal-ventral (DV) axis patterning. Subsequently, mathematical …

Molluscs are extremely diverse invertebrate animals with a rich fossil record, highly
divergent life cycles, and considerable economical and ecological importance. Key …

This article proposes that biologically plausible theories of behavior can be constructed by
following a method of “phylogenetic refinement,” whereby they are progressively elaborated …

Acorn worms, also known as enteropneust (literally,'gut-breathing') hemichordates, are
marine invertebrates that share features with echinoderms and chordates. Together, these …

The origin of the pentaradial body plan of echinoderms from a bilateral ancestor is one of the
most enduring zoological puzzles,. Because echinoderms are defined by morphological …

It has been hypothesized that a condensed nervous system with a medial ventral nerve cord
is an ancestral character of Bilateria. The presence of similar dorsoventral molecular …

To elucidate the evolutionary origin of nervous system centralization, we investigated the
molecular architecture of the trunk nervous system in the annelid Platynereis dumerilii …

The regulation of body axis specification in the common ancestor of bilaterians remains
controversial. BMP signaling appears to be an ancient program for patterning the secondary …

Most animals evolved from a common ancestor, Urbilateria, which already had in place the
developmental genetic networks for shaping body plans. Comparative genomics has …

Neuroectodermal signalling centres induce and pattern many novel vertebrate brain
structures but are absent, or divergent, in invertebrate chordates. This has led to the idea …