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Sistemas de desintoxicación de amoníaco mitocondrial aviar y mamífero en el hígado de tortuga
Science (New York, N.Y.)
|April 19, 1985
Resumen
Las tortugas del desierto y de Texas poseen enzimas mitocondriales hepáticas únicas para la desintoxicación del amoníaco. Esto sugiere que los reptiles antiguos tenían sistemas duales de metabolismo de amoníaco antes de que los principales linajes de vertebrados divergieran.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- Biología evolutiva Biología evolutiva.
- La Fisiología Comparada.
Sus antecedentes:
- La desintoxicación del amoníaco es crucial para el metabolismo de los aminoácidos.
- Las aves y los reptiles superiores utilizan la glutamina sintetasa (GS) para la desintoxicación del amoníaco.
- Los mamíferos utilizan la carbamilfosfato sintetasa-I (CPS-I) y la ornitina transcarbamilasa (OTC) para la desintoxicación del amoníaco.
Objetivo del estudio:
- Para investigar las vías de desintoxicación del amoníaco presentes en las mitocondrias del hígado de las tortugas del desierto (Gopherus agassizii) y las tortugas de Texas (G. berlandieri).
- Comprender las implicaciones evolutivas de estas vías en los reptiles chelónidos.
Principales métodos:
- Aislamiento mitocondrial del tejido hepático de tortuga.
- Los ensayos de actividad enzimática para la glutamina sintetasa, la carbamilfosfato sintetasa-I y la ornitina transcarbamilasa.
Principales resultados:
- Las mitocondrias hepáticas de ambas especies de tortugas contenían glutamina sintetasa.
- Además, las mitocondrias del hígado de tortuga exhibieron actividades de carbamilfosfato sintetasa-I y ornitina transcarbamilasa.
- Estos hallazgos indican la presencia tanto de los sistemas de desintoxicación de amoníaco de aves/reptiles superiores como de mamíferos en los reptiles chelónidos.
Conclusiones:
- Los reptiles chelónidos poseen tanto la glutamina sintetasa como las vías de la carbamilfosfato sintetasa-I/ornitina transcarbamilasa para la desintoxicación del amoníaco.
- Este sistema dual sugiere que estas vías estaban presentes en los reptiles madre antes de la divergencia de los linajes de aves y mamíferos.
- Los hallazgos proporcionan información sobre la historia evolutiva del metabolismo del nitrógeno en los vertebrados.
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