Amphioxus as a model to study the evolution of development in chordates

Abstract

Cephalochordates and tunicates represent the only two groups of invertebrate chordates, and extant cephalochordates – commonly known as amphioxus or lancelets – are considered the best proxy for the chordate ancestor, from which they split around 520 million years ago. Amphioxus has been an important organism in the fields of zoology and embryology since the 18th century, and the morphological and genomic simplicity of cephalochordates (compared to vertebrates) makes amphioxus an attractive model for studying chordate biology at the cellular and molecular levels. Here we describe the life cycle of amphioxus, and discuss the natural histories and habitats of the different species of amphioxus. We also describe their use as laboratory animal models, and discuss the techniques that have been developed to study different aspects of amphioxus.

Characterization of a putative orexin receptor in Ciona intestinalis sheds light on the evolution of the orexin/hypocretin system in chordates

“…Model species within invertebrate deuterostomes from the (sub)phyla of tunicates (e.g., the marine vase tunicate Ciona intestinalis), cephalochordates (e.g., lancelets) and echinoderms (e.g., sea urchin) can be used to bridge the gap between vertebrates and invertebrates [7][8][9] . Various neuropeptides and neuropeptide receptors have been identified in invertebrates with primitive nervous system, e.g., in tunicates 10,11 , cephalochordates 13,14 , echinoderms 8,12 and non-bilaterian cnidarians 13 .…”