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El desarrollo de las aletas en un pez cartilaginoso y el origen de las extremidades de los vertebrados
Mikiko Tanaka1, Andrea Münsterberg, W Gary Anderson
1Division of Cell and Developmental Biology, Wellcome Trust Biocentre, University of Dundee, Dow Street, Dundee DD1 5EH, UK. mtanaka@dundee.ac.uk
Nature
|April 5, 2002
Resumen
La evolución de las extremidades de los tetrápodos a partir de las aletas se explora en los embriones de pez perro. La expresión génica sugiere que la identidad de las extremidades evolucionó temprano, pero el gen Shh.
Área de la Ciencia:
- Biología del desarrollo evolutivo Biología del desarrollo evolutivo
- Embriología comparada y comparativa.
- Paleontología Paleontología.
Sus antecedentes:
- La teoría del plegamiento de la aleta lateral propone que las extremidades de los tetrápodos evolucionaron a partir de aletas subdivididas.
- Comprender la evolución temprana de las extremidades requiere el estudio de los vertebrados primitivos.
Objetivo del estudio:
- Investigar el desarrollo de las aletas en embriones de pez perro (Scyliorhinus canicula).
- Examinar la expresión génica relacionada con el desarrollo de las extremidades en un pez cartilaginoso primitivo.
Principales métodos:
- Microscopía electrónica de barrido de embriones de pez perro.
- Análisis de la expresión génica de Engrailed-1, Tbx4, Tbx5 y dHand.
Principales resultados:
- No se detectaron pliegues de aleta lateral en los embriones de pez perro.
- La expresión Engrailed-1 indica la compartimentación del cuerpo.
- Los genes Tbx4 y Tbx5 especifican la identidad de las extremidades, similar a los vertebrados superiores.
- Las transcripciones de Shh estaban ausentes, pero dHand se expresó en aletas.
- El eje de la aleta del pez perro es paralelo al eje del cuerpo.
Conclusiones:
- Los genes de identidad de extremidades (Tbx4, Tbx5) se conservan temprano en la evolución de los vertebrados.
- La ausencia de Shh en el pez perro sugiere un papel crítico en la liberación de las aletas del eje del cuerpo durante la evolución de las extremidades de los tetrápodos.
- Shh probablemente jugó un papel clave en el establecimiento de un eje de extremidad separado.
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