Lungfish Neoceratodus forsteri: Activities of Ornithine-Urea Cycle and Enzymes

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Science  21 Jul 1967:
Vol. 157, Issue 3786, pp. 316-317
DOI: 10.1126/science.157.3786.316


The level of activity of the ornithine-urea cycle is low in the liver of the permanently aquatic Australian lungfish. The rate of incorporation of 14C-bicarbonate into urea by liver slices was only 100th of that previously observed in the estivating African lungfish Protopterus dolloi. The activities of enzymes of the ornithine-urea cycle were similarly reduced. The low activity of this cycle in Neoceratodus is consistent with its exclusively aquatic nature.