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Componentes de fototransducción parietal-ojo y sus potenciales implicaciones evolutivas.
Chih-Ying Su1, Dong-Gen Luo, Akihisa Terakita
1Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. chih-ying.su@yale.edu
Science (New York, N.Y.)
|March 18, 2006
Resumen
El fotorreceptor del ojo parietal utiliza dos vías de luz: una sensible al azul y otra sensible al verde. Los investigadores identificaron los componentes moleculares, incluidas las opsinas nuevas, revelando información sobre la evolución del sistema visual.
Área de la Ciencia:
- Biología de los fotorreceptores.
- Evolución del sistema visual Evolución del sistema visual
- Biología celular molecular Biología celular molecular.
Sus antecedentes:
- El fotorreceptor del ojo parietal exhibe un sistema de señalización dual único dentro de una sola célula.
- Posee una vía hiperpolarizante sensible a la luz azul y una vía despolarizante sensible a la luz verde.
Objetivo del estudio:
- Identificar los componentes moleculares de las dos distintas vías de señalización lumínica en el fotorreceptor del ojo parietal.
- Para aclarar los roles de opsinas específicas y proteínas G en la mediación de estas respuestas.
Principales métodos:
- Identificación molecular de las opsinas y las subunidades alfa de la proteína G.
- Registros electrofisiológicos unicelulares para caracterizar las respuestas evocadas por la luz.
Principales resultados:
- Se identificaron dos opsinas: la pinopsina (sensible al azul) y la parietopsina (sensible al verde).
- La señalización involucró gustducina-alfa y Galphao, pero no varilla o cono transducina-alfa.
- La electrofisiología confirmó que Galphao media la respuesta despolarizante y gustducina-alfa media la respuesta hiperpolarizante.
Conclusiones:
- La vía de señalización parietopsina-Galphao es responsable de la respuesta despolarizadora a la luz verde.
- La gustducina-alfa probablemente media en la respuesta hiperpolarizante a la luz azul.
- Estos hallazgos ofrecen información sobre los orígenes evolutivos de la fototransducción de bastón y cono.
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