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Los genomas de las algas revelan el mosaicismo evolutivo y el destino de los nucleomorfos
Bruce A Curtis1, Goro Tanifuji, Fabien Burki
1Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada.
Nature
|December 4, 2012
Resumen
Las algas criptofitas y cloraracniófitas retienen nucleomorfos, núcleos remanentes de eventos endosimbióticos. La secuenciación del genoma revela el mosaicismo genético y explica por qué los genes esenciales permanecen encerrados dentro de estas estructuras únicas.
Área de la Ciencia:
- Biología celular de las células eucariotas.
- Investigación de la endosimbiosis en la investigación de la endosimbiosis.
- Genómica de las algas.
Sus antecedentes:
- Las algas criptofitas y cloraracniófitas son modelos para la endosimbiosis secundaria.
- Estas algas únicamente retienen nucleomorfos, núcleos remanentes de endosimbiontes de algas engullidas.
- La comprensión de la persistencia de los nucleomorfos es clave para la endosimbiosis eucariota-eucariota.
Objetivo del estudio:
- Secuenciar y analizar los genomas nucleares de Guillardia theta (criptofito) y Bigelowiella natans (cloracniofito).
- Investigar la base genética y las implicaciones evolutivas de la persistencia de los nucleomorfos.
- Elucida la dinámica de transferencia génica y la distribución funcional de genes en estas células complejas.
Principales métodos:
- Secuenciación del genoma completo de Guillardia theta y Bigelowiella natans.
- Análisis filogenómicos para reconstruir las relaciones evolutivas.
- Predicciones de orientación subcelular para determinar la localización y la función de los genes.
Principales resultados:
- Ambos genomas superan los 21.000 genes de proteínas y son ricos en intrones.
- Bigelowiella natans muestra un extenso empalme alternativo.
- Se observó un extenso mosaicismo genético y bioquímico, con genes de huésped y endosimbiontes sirviendo a múltiples compartimentos celulares.
- Transferencia de genes en curso de mitocondria al núcleo, pero no hay transferencia de plástido al núcleo o de nucleomorfo al núcleo.
Conclusiones:
- La falta de plastido y la transferencia de genes de nucleomorfo a núcleo explica la retención de genes esenciales dentro de los nucleomorfos.
- El mosaicismo genético y bioquímico es un sello distintivo de estos sistemas endosimbióticos secundarios.
- Estos hallazgos proporcionan información fundamental sobre la evolución y el mantenimiento de complejos genomas eucarióticos.
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