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Los círculos de un solo gen en los genomas de los cloroplastos dinoflagelados
Z Zhang1, B R Green, T Cavalier-Smith
1Canadian Institute for Advanced Research Evolutionary Biology Programme, Department of Botany, University of British Columbia, Vancouver.
Nature
|July 17, 1999
Resumen
Los cloroplastos dinoflagelados tienen una estructura genómica única con genes individuales en minicírculos separados. Este descubrimiento revela información sobre la evolución de estos productores primarios acuáticos cruciales.
Área de la Ciencia:
- Biología marina Biología marina.
- Evolución molecular de la evolución molecular.
- La fisiología de la fisiología.
Sus antecedentes:
- Los dinoflagelados fotosintéticos son los principales productores primarios acuáticos y causan floraciones de algas dañinas.
- Los cloroplastos dinoflagelados poseen características únicas, que incluyen tres membranas de envoltura y pigmentos específicos de recolección de luz.
- Investigaciones anteriores enfrentaron desafíos en la secuenciación de genes de cloroplastos dinoflagelados debido a su inusual organización genómica.
Objetivo del estudio:
- Para dilucidar la estructura única del genoma del ADN de los cloroplastos de los dinoflagelados.
- Obtener y analizar secuencias completas de ARN ribosómico de cloroplasto y genes de proteínas.
- Para investigar los orígenes evolutivos de los cloroplastos dinoflagelados.
Principales métodos:
- Secuenciación del ARN ribosomal del cloroplasto y de siete genes de proteínas del cloroplasto de Heterocapsa triquetra.
- Análisis de la organización genómica, incluyendo cromosomas minicirculares y regiones no codificantes.
- Análisis filogenético para determinar las relaciones evolutivas.
Principales resultados:
- Los cloroplastos dinoflagelados exhiben una organización única de "un gen-un círculo" en los cromosomas minicirculares.
- Los genes secuenciados son muy divergentes en comparación con otros genomas de cloroplastos conocidos.
- Se identificó una región no codificante tripartita conservada en cada círculo, lo que sugiere un papel en la replicación y se conserva a través de la conversión génica.
- La evidencia sugiere que esta organización genómica puede ser ancestral en los dinoflagelados peridineos.
Conclusiones:
- Los cloroplastos dinoflagelados poseen una estructura genómica distintiva y previamente no caracterizada.
- Los análisis filogenéticos apoyan el origen de los cloroplastos dinoflagelados a través de la endosimbiosis secundaria, con vínculos con el cromistán y los cloroplastos de algas rojas.
- Las características genómicas únicas proporcionan información sobre la evolución y la biología de estos microorganismos ecológicamente significativos.
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