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50 millones de años de estancamiento genómico en bacterias endosimbióticas
Ivica Tamas1, Lisa Klasson, Björn Canbäck
1Department of Molecular Evolution, Evolutionary Biology Center, University of Uppsala, Uppsala, Sweden.
Science (New York, N.Y.)
|June 29, 2002
Resumen
Buchnera aphidicola, endosimbiontes de los áfidos, exhiben una extrema estabilidad del genoma durante 50-70 millones de años, a diferencia de sus parientes labiles. Esta estanqueidad genómica sugiere que Buchnera ya no es una fuente de innovación ecológica para los áfidos.
Área de la Ciencia:
- La genómica microbiana es la genómica microbiana.
- Biología evolutiva Biología evolutiva.
- Las relaciones simbióticas son relaciones simbióticas.
Sus antecedentes:
- Buchnera aphidicola son endosimbiontes obligados de los áfidos, esenciales para la supervivencia del huésped.
- La comprensión de la evolución del genoma en endosimbiontes proporciona información sobre las interacciones huésped-microbio.
- La genómica comparativa pone de relieve las trayectorias evolutivas de los genomas bacterianos.
Objetivo del estudio:
- Para comparar la estabilidad del genoma de Buchnera aphidicola con sus parientes de vida libre.
- Para investigar los mecanismos y las implicaciones de la estasis extrema del genoma en Buchnera aphidicola.
Principales métodos:
- Secuenciación del genoma completo de dos cepas de Buchnera aphidicola.
- Análisis genómico comparativo con bacterias relacionadas de vida libre (por ejemplo, Escherichia coli, Salmonella spp. En el caso de las personas que se encuentran en situación de exclusión social.
- Análisis de los reordenamientos cromosómicos, el contenido de los genes y la evolución de la secuencia.
Principales resultados:
- Los genomas de Buchnera aphidicola muestran una estabilidad sin precedentes, sin reordenamientos cromosómicos observados o adquisiciones de genes durante 50-70 millones de años.
- La evolución de la secuencia significativa, la inactivación de genes y la pérdida de genes se produjeron a pesar de la estasis genómica.
- Sus parientes cercanos como Escherichia coli y Salmonella spp. exhiben genomas más de 2000 veces más labiles en contenido y orden genético.
- El estancamiento genómico en Buchnera está relacionado con la pérdida de fagos, secuencias repetidas y el gen recA.
Conclusiones:
- Buchnera aphidicola posee el genoma más estable documentado hasta la fecha.
- Es probable que la pérdida de elementos genéticos clave (fagos, repeticiones, recA) sea la base de este estancamiento genómico extremo.
- Esta estabilidad genómica sugiere que Buchnera aphidicola ha perdido su capacidad de innovación ecológica, impactando la evolución de los áfidos.
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