Expression of the head gene Lox22-Otx in the leech Helobdella and the origin of the bilaterian body plan.
Dev Biol
; 201(1): 101-12, 1998 Sep 01.
Article
en En
| MEDLINE
| ID: mdl-9733577
The orthodenticle orthologue Lox22-Otx was isolated from an annelid worm, the leech Helobdella triserialis. In situ hybridization reveals that embryonic expression of Lox22-Otx RNA is primarily restricted to an unsegmented head domain, including tissues in the foregut, surface ectoderm, and the head ganglion of the central nervous system. The patterns of head expression form concentric rings about the stomadeum and mark tissue domains that exhibit discrete behaviors during later morphogenesis and differentiation. Expression was also observed in one to two bilateral pairs of neurons in each segmental ganglion or neuromere of the body trunk. The largely head-specific expression of Lox22-Otx in this annelid species supports data from two other bilaterian phyla in suggesting the existence of a genetically defined head/trunk distinction. We suggest here that this head/trunk distinction is a synapomorphy of the Bilateria as a whole, and that it reflects the body plan of an early bilaterian ancestor. In addition, we discuss the possibility that the radial organization of gene expression and cell lineages in the leech's head domain may reflect the symmetry properties of a prebilaterian ancestor that had a radially symmetric body plan.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Proteínas de Homeodominio
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Regulación del Desarrollo de la Expresión Génica
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Tipificación del Cuerpo
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Embrión no Mamífero
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Sanguijuelas
Límite:
Animals
Idioma:
En
Revista:
Dev Biol
Año:
1998
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos