QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

This Article Full Text (PDF) References Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Walsh, P. Search for Related Content PubMed PubMed Citation Articles by Walsh, P. Social Bookmarking                         What's this?

Journal of Experimental Biology, Vol 198, Issue 3 755-766, Copyright © 1995 by Company of Biologists

JOURNAL ARTICLES

Subcellular localization and biochemical properties of the enzymes of carbamoyl phosphate and urea synthesis in the batrachoidid fishes Opsanus beta, Opsanus tau and Porichthys notatus

P Walsh

The subcellular localization and biochemical properties of the enzymes of carbamoyl phosphate and urea synthesis were examined in three representatives of fishes of the family Batrachoididae, the gulf toadfish (Opsanus beta), the oyster toadfish (Opsanus tau) and the plainfin midshipman (Porichthys notatus). The primary objective of the study was to compare the biochemical characteristics of these fishes, which represent a range between ammoniotelism and ureotelism (O. beta being facultatively ureotelic), with previous patterns observed for an ammoniotelic teleost (Micropterus salmoides, the largemouth bass) and an obligate ureogenic elasmobranch (Squalus acanthias, the dogfish shark). The present study documents the expression of mitochondrial carbamoyl phosphate synthetase (CPSase) III and cytosolic CPSase II (and its associated enzymes of pyrimidine synthesis, dihydro-orotase and aspartate carbamoyltransferase) in the livers of all three batrachoidid species. Both mitochondrial and cytosolic activities of arginase were present in the livers of all three species, as were cytosolic glutamine synthetase and argininosuccinate synthetase and lyase. However, O. beta also showed mitochondrial glutamine synthetase activity and higher total hepatic levels of glutamine synthetase than either O. tau or P. notatus. Taken together, these observations confirm that the arrangement of these enzymes in the batrachoidid fishes has greater similarity to that of M. salmoides than to that of S. acanthias. However, differences within the family appear to coincide with the different nitrogen excretion strategies. O. tau and P. notatus are primarily ammoniotelic and most closely resemble the ammoniotelic M. salmoides, whereas ureotelism in O. beta is correlated with the presence of a mitochondrial glutamine synthetase and the ability to induce higher total glutamine synthetase activities than O. tau or P. notatus. Additionally, isolated mitochondria from O. beta were able to generate citrulline from glutamine, whereas those from O. tau were not. Also in contrast to S. acanthias, glutamine synthetase activities in the mitochondria of O. beta are consistently lower than those of CPSase III. This and other kinetic observations lend support to the hypothesis that glutamine synthetase may be an important regulatory control point in determining rates of ureogenesis in O. beta.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?

This article has been cited by other articles:

				S. F. Chew, M. Y. Wong, W. L. Tam, and Y. K. Ip The snakehead Channa asiatica accumulates alanine during aerial exposure, but is incapable of sustaining locomotory activities on land through partial amino acid catabolism J. Exp. Biol., February 15, 2003; 206(4): 693 - 704. [Abstract] [Full Text] [PDF]

				P. M. Anderson, M. A. Broderius, K. C. Fong, K. N. T. Tsui, S. F. Chew, and Y. K. Ip Glutamine synthetase expression in liver, muscle, stomach and intestine of Bostrichthys sinensis in response to exposure to a high exogenous ammonia concentration J. Exp. Biol., July 15, 2002; 205(14): 2053 - 2065. [Abstract] [Full Text] [PDF]

				B. F. Terjesen, T. D. Chadwick, J. A. J. Verreth, I. Ronnestad, and P. A. Wright Pathways for urea production during early life of an air-breathing teleost, the African catfish Clarias gariepinus Burchell J. Exp. Biol., March 8, 2002; 204(12): 2155 - 2165. [Abstract] [Full Text] [PDF]

				K Iwata, M Kajimura, and T Sakamoto Functional ureogenesis in the gobiid fish Mugilogobius abei J. Exp. Biol., January 12, 2000; 203(24): 3703 - 3715. [Abstract] [PDF]

				T. E. Lindley, C. L. Scheiderer, P. J. Walsh, C. M. Wood, H. L. Bergman, A. L. Bergman, P. Laurent, P. Wilson, and P. M. Anderson Muscle as the Primary Site of Urea Cycle Enzyme Activity in an Alkaline Lake-adapted Tilapia, Oreochromis alcalicus grahami J. Biol. Chem., October 15, 1999; 274(42): 29858 - 29861. [Abstract] [Full Text] [PDF]

				T. Chadwick and P. Wright Nitrogen excretion and expression of urea cycle enzymes in the atlantic cod (Gadus morhua l.): a comparison of early life stages with adults J. Exp. Biol., January 10, 1999; 202(19): 2653 - 2662. [Abstract] [PDF]

				J. J. Korte, W. L. Salo, V. M. Cabrera, P. A. Wright, A. K. Felskie, and P. M. Anderson Expression of Carbamoyl-phosphate Synthetase III mRNA during the Early Stages of Development and in Muscle of Adult Rainbow Trout (Oncorhynchus mykiss) J. Biol. Chem., March 7, 1997; 272(10): 6270 - 6277. [Abstract] [Full Text] [PDF]

				J. Hong, W. L. Salo, and P. M. Anderson Nucleotide Sequence and Tissue-specific Expression of the Multifunctional Protein Carbamoyl-phosphate Synthetase-Aspartate Transcarbamoylase-Dihydroorotase (CAD) mRNA in Squalus acanthias J. Biol. Chem., June 9, 1995; 270(23): 14130 - 14139. [Abstract] [Full Text] [PDF]