Mitochondrial citrulline synthesis from ammonia and glutamine in the liver of ureogenic air-breathing catfish, Clarias batrachus (Linnaeus).
Indian J Exp Biol
;
2007 Dec; 45(12): 1073-9
Artigo
em Inglês
| IMSEAR
| ID: sea-61028
ABSTRACT
The possible synthesis of citrulline, a rate limiting step for urea synthesis via the ornithine-urea cycle (OUC) in teleosts was tested both in the presence of ammonia and glutamine as nitrogen-donating substrates by the isolated liver mitochondria of ureogenic air-breathing walking catfish, C. batrachus. Both ammonia and glutamine could be used as nitrogen-donating substrates for the synthesis of citrulline by the isolated liver mitochondria, since the rate of citrulline synthesis was almost equal in presence of both the substrates. The citrulline synthesis by the isolated liver mitochondria requires succinate at a concentration of 0.1 mM as an energy source, and also requires the involvement of intramitochondrial carbonic anhydrase activity for supplying HCO3 as another substrate for citrulline synthesis. The rate of citrulline synthesis was further stimulated significantly by the isolated liver mitochondria of the fish after pre-exposure to 25 mM NH4Cl for 7 days. Due to possessing this biochemical adaptational strategy leading to the amelioration of ammonia toxicity mainly by channeling ammonia directly and/or via the formation of glutamine to the OUC, this air-breathing catfish could succeed in surviving in high external ammonia, which it faces in its natural habitat in certain seasons of the year.
Texto completo:
DisponíveL
Índice:
IMSEAR (Sudeste Asiático)
Assunto principal:
Ureia
/
Peixes-Gato
/
Citrulina
/
Anidrases Carbônicas
/
Ácido Succínico
/
Vias Biossintéticas
/
Glutamina
/
Amônia
/
Animais
/
Mitocôndrias
Idioma:
Inglês
Revista:
Indian J Exp Biol
Ano de publicação:
2007
Tipo de documento:
Artigo
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