Respiration in the muscle mitochondria of the mudskipper, Boleophthalmus boddaerti

Abstract

1. 1. Morphologically and biochemically intact muscle mitochondria were isolated from Boleophthalmus boddaerti. 2. 2. The optimal osmolality was observed to be 300 mOsm which is higher than osmolality (250–270 mOsm) normally used for other organisms. 3. 3. Oxidative phosphorylation in the muscle mitochondria of B. boddaerti was stimulated by glutamate, glutamine, α-ketoglutarate, malate and succinate, while citrate, isocitrate and fumarate were not effective substrates. 4. 4. Phosphorylation in the muscle mitochondria was inhibited by 1 mM 2,4-dinitrophenol, 0.2 μM antimycin A and 1 mM KCN. 5. 5. Rotenone inhibited phosphorylation in all substrates tested except succinate. 6. 6. Oxygen consumption in the presence of a substrate and ADP was stimulated by the uncoupling agent FCCP. 7. 7. The presence of the three sites of coupling in the electron transport system of B. boddaerti was confirmed but coupling in Sites 2 and 3 was not as efficient as in Site 1. 8. 8. It can be concluded that the metabolism of the muscle mitochondria of B. boddaerti, apart from some minor differences, is similar to that of other organisms studied.