title: Amphioxus AmphiDelta: evolution of Delta protein structure, segmentation, and neurogenesis.
abstract: The amphioxus genome has a single Delta gene (AmphiDelta) encoding a protein 766 amino acids long. Comparison of Delta proteins of amphioxus and other animals indicates that AmphiDelta retains features of a basal bilaterian Delta protein--in having nine epidermal growth factor (EGF) repeats and also in having characteristic numbers of amino acids separating successive cysteines between and within EGF repeats. During development, AmphiDelta is expressed in the forming somites, in some regions of pharyngeal endoderm, and in cells (presumably differentiating neurons) scattered in both the neural plate and ectoderm. Expression is strongly associated with cells initiating movements to separate themselves from parent epithelia, either en masse by evagination (endoderm and mesoderm) or by delamination as isolated cells (ectoderm). The AmphiDelta-expressing cells delaminating from the ectoderm apparently migrate beneath it as they begin differentiating into probable sensory neurons, suggesting a scenario for the evolutionary origin of the placode-derived neurons of vertebrate cranial ganglia.
authors.affiliation: Division of Marine Biology Research, Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093-0202, USA.
authors.forename: Stacy L K
authors.initials: SL
authors.lastname: Rasmussen
authors.forename: Linda Z
authors.initials: LZ
authors.lastname: Holland
authors.forename: Michael
authors.initials: M
authors.lastname: Schubert
authors.forename: Laura
authors.initials: L
authors.lastname: Beaster-Jones
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Holland
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002816:Chordata, Nonvertebrate / Q000196:embryology / Q000378:metabolism*; D002970:Cleavage Stage, Ovum / Q000378:metabolism* / Q000502:physiology; D019143:Evolution, Molecular; D018507:Gene Expression Regulation, Developmental; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D009420:Nervous System / Q000378:metabolism*; D038081:Organogenesis; D051880:Receptors, Notch / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051880:Receptors, Notch; C064045:delta protein