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Science 19 April 1985:
Vol. 228. no. 4697, pp. 349 - 351
DOI: 10.1126/science.228.4697.349
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Articles

Avian and Mammalian Mitochondrial Ammonia-Detoxifying Systems in Tortoise Liver

JAMES W. CAMPBELL 1, DARWIN D. SMITH JR. 1, and JEAN E. VORHABEN 1

1 Department of Biology, Rice University, Houston, Texas 77251

Liver mitochondria from the desert tortoise Gopherus agassizii and the Texas tortoise G. berlandieri contain glutamine synthetase, the enzyme used by birds and higher reptiles to detoxify ammonia generated intramitochondrially during amino acid catabolism. Tortoise mitochondria also contain carbamyl phosphate synthetase-I and ornithine transcarbamylase, the enzymes used by mammals for this purpose. Since chelonid reptiles have changed little since their divergence from the stem reptiles, this finding suggests that both systems were present in the latter before the emergence of the ruling reptile, avian, and mammalian lines of descent.

Submitted on November 15, 1984
Accepted on December 20, 1985


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Evolution of urea synthesis in vertebrates: the piscine connection.
T. Mommsen and P. Walsh (1989)
Science 243, 72-75
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Science. ISSN 0036-8075 (print), 1095-9203 (online)