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Functional ureogenesis and adaptation to ammonia metabolism in Indian freshwater air-breathing catfishes

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Abstract

The Indian freshwater air-breathing catfishes Heteropneustes fossilis and Clarias batrachus are hardy and capable of living in derelict water bodies and tolerating temporary water deprivation. Several studies have been made on their ureogenic adaptations, ureogenic metabolic machinery, and regulation under different physiological and environmental conditions. Both species are potentially ureogenic teleosts expressing the complete repertoire of ornithine-urea cycle (OUC) enzymes, not only in hepatic tissue but also in certain non-hepatic tissues. This review compiles the information available on the peculiarities of their ureogenic machinery and the induction of ureogenesis during adaptation to various stressful conditions such as exposure to high environmental ammonia, water deprivation, highly alkaline environment, etc. The biochemical profile and pattern of physiological adaptations, suggesting an intermediary status of these fishes in the evolution of ureotely in vertebrates, is discussed.

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Acknowledgements

This study was partly supported by research grants awarded to the authors by the Department of Biotechnology and Department of Science & Technology, Govt. of India, New Delhi.

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  1. Biochemical Adaptation Laboratory, Department of Zoology, North-Eastern Hill University, Shillong, 793022, India

    N. Saha

  2. Biochemical Adaptation Laboratory, Department of Zoology, Banaras Hindu University, Varanasi, 221005, India

    B. K. Ratha

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Saha, N., Ratha, B.K. Functional ureogenesis and adaptation to ammonia metabolism in Indian freshwater air-breathing catfishes. Fish Physiol Biochem 33, 283–295 (2007). https://doi.org/10.1007/s10695-007-9172-3

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