Ascidians and the Plasticity of the Chordate Developmental Program

Little is known about the ancient chordates that gave rise to the first vertebrates, but the descendants of other invertebrate chordates extant at the time still flourish in the ocean. These invertebrates include the cephalochordates and tunicates, whose larvae share with vertebrate embryos a common...

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Published inCurrent biology Vol. 18; no. 14; pp. R620 - R631
Main Authors Lemaire, Patrick, Smith, William C., Nishida, Hiroki
Format Journal Article
LanguageEnglish
Published England Elsevier Inc 22.07.2008
Elsevier
Subjects
Animals
Body Patterning
Cellular Biology
Cephalochordata
Chordata
Female
Gastrula - cytology
Larva - growth & development
Life Sciences
Male
Marine
Metamorphosis, Biological
Models, Biological
Reproduction
Urochordata - growth & development
Urochordata - physiology
Xenopus - growth & development
Xenopus - physiology
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Summary:Little is known about the ancient chordates that gave rise to the first vertebrates, but the descendants of other invertebrate chordates extant at the time still flourish in the ocean. These invertebrates include the cephalochordates and tunicates, whose larvae share with vertebrate embryos a common body plan with a central notochord and a dorsal nerve cord. Tunicates are now thought to be the sister group of vertebrates. However, research based on several species of ascidians, a diverse and wide-spread class of tunicates, revealed that the molecular strategies underlying their development appear to diverge greatly from those found in vertebrates. Furthermore, the adult body plan of most tunicates, which arises following an extensive post-larval metamorphosis, shows little resemblance to the body plan of any other chordate. In this review, we compare the developmental strategies of ascidians and vertebrates and argue that the very divergence of these strategies reveals the surprising level of plasticity of the chordate developmental program and is a rich resource to identify core regulatory mechanisms that are evolutionarily conserved in chordates. Further, we propose that the comparative analysis of the architecture of ascidian and vertebrate gene regulatory networks may provide critical insight into the origin of the chordate body plan.
Bibliography:ObjectType-Article-2
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ISSN:0960-9822
1879-0445
DOI:10.1016/j.cub.2008.05.039