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Science 21 July 1967:
Vol. 157. no. 3786, pp. 316 - 317
DOI: 10.1126/science.157.3786.316
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Articles

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

Leon Goldstein 1, Peter A. Janssens 2, and Roy P. Forster 3

1 Department of Physiology, Harvard Medical School, Boston, Massachusetts
2 Department of Physiological Chemistry, University of Wisconsin, Madison
3 Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire

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.

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Science. ISSN 0036-8075 (print), 1095-9203 (online)