El desarrollo de Acoel indica la evolución independiente de la boca y el ano bilaterales
Andreas Hejnol1, Mark Q Martindale
1Kewalo Marine Laboratory, PBRC, University of Hawaii, 41 Ahui Street, Honolulu, Hawaii 96813, USA. hejnol@hawaii.edu
Nature
|September 23, 2008
Resumen
Los gusanos planos Acoel, el grupo hermano de todos los Bilateria, poseen una única abertura digestiva. La expresión génica sugiere que esta abertura es homóloga a la boca bilateral, lo que desafía la evolución simultánea de la boca a través del intestino.
Área de la Ciencia:
- Biología del desarrollo Biología del desarrollo.
- Biología evolutiva Biología evolutiva.
- Evolución de los animales Evolución de los animales.
Sus antecedentes:
- La mayoría de los animales bilaterales tienen un intestino a través con boca y ano separados.
- Se hipotetiza que la evolución de la vía intestinal implica el desarrollo simultáneo de ambas aberturas a partir de una sola ranura blastoporal.
- Los gusanos planos Acoel, hermanos de todos los demás Bilateria, poseen una única abertura digestiva.
Objetivo del estudio:
- Para investigar el origen evolutivo del bilateriano a través del intestino.
- Para determinar la homología del acoel única apertura a la boca y el ano de otros bilaterians.
- Para estudiar los patrones de expresión génica relacionados con el desarrollo intestinal en el acoel Convolutriloba longifissura.
Principales métodos:
- Estudió patrones de expresión génica durante el desarrollo de Convolutriloba longifissura.
- Examinó la expresión de genes clave involucrados en el patrón bilateral del intestino delantero y posterior, incluidos el braquio, el ganso, el caudal y la ortopedia.
- Se analizó la expresión de bmp2/4 en regiones ectodérmicas.
Principales resultados:
- La boca de acoel muestra expresión de braquiuria y goosecoid, lo que sugiere homología con la boca bilateral.
- Los genes asociados con el trasero bilateral (caudal, ortopedia, braquiuria) se expresan en una región posterior distinta.
- Un dominio dorsal de expresión bmp2/4 separa la región oral anterior de la región posterior asociada al intestino posterior.
Conclusiones:
- Los hallazgos contradicen la hipótesis de la evolución simultánea de la boca y el ano desde una abertura blastoporal común.
- La única abertura en acoels es probablemente homólogo a la boca bilateral.
- A través del intestino puede haber evolucionado independientemente en diferentes linajes de animales, en lugar de surgir una vez en el antepasado bilateral común.
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