Expression of Carbamoyl-phosphate Synthetase III mRNA during the Early Stages of Development and in Muscle of Adult Rainbow Trout (Oncorhynchus mykiss)

doi:10.1074/jbc.272.10.6270

Expression of Carbamoyl-phosphate Synthetase III mRNA during the Early Stages of Development and in Muscle of Adult Rainbow Trout (Oncorhynchus mykiss)*

From the ^‡ Department of Biochemistry and Molecular Biology, University of Minnesota-Duluth, Duluth, Minnesota 55812 and the
^∥ Department of Zoology, University of Guelph, Guelph, Ontario N1G 2W1, Canada

^§ To whom correspondence should be addressed. Tel.: 218-726-7921; Fax: 218-726-8014.

Abstract

It has been reported that the activities of the urea cycle-related enzymes ornithine carbamoyltransferase and carbamoyl-phosphate synthetase III (CPSase III) are induced during early life stages of ammonotelic rainbow trout (Oncorhynchus mykiss), suggesting that the urea cycle may play a physiological role in early development in teleost fish (Wright, P. A., Felskie, A., and Anderson, P. M. (1995) J. Exp. Biol. 198, 127-135). CPSase III cDNA prepared from embryo mRNA was sequenced, confirming the existence of the CPSase III gene in trout and its expression. The deduced amino acid sequence of the CPSase III is homologous to other CPSases. Supporting evidence for the expression of CPSase III activity in trout embryos was obtained by demonstrating expression of CPSase III mRNA as early as day 3 post-fertilization, reaching a maximum at 10-14 days, declining to a minimum at day 70, and then increasing to a relatively constant level from days 90 to 110 (relative to total RNA). Unexpectedly, in tissues of adult and fingerling trout, CPSase III mRNA was found to be present in muscle but not in other tissues, including liver. This finding was confirmed by assay of extracts, which showed CPSase III and ornithine carbamoyltransferase activity in muscle but not in other tissues. The pyrimidine nucleotide pathway-related CPSase II mRNA was expressed in all tissues.

Footnotes

↵^¶ On leave from the Department of Genetics, LaLaguna University, LaLaguna, Tenerife, Spain.
↵* This research was supported by National Science Foundation Grant DCB-9105797. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

CPSase

carbamoyl-phosphate synthetase

AGA

N-acetyl-L-glutamate

PCR

polymerase chain reaction

bp

base pair(s).
↵² P. M. Anderson, unpublished observations.
↵³ A. K. Felskie, P. M. Anderson, and P. A. Wright, unpublished observations.
↵⁴ W. L. Salo and P. M. Anderson, unpublished observations.
- Received August 15, 1996.
- Revision received December 9, 1996.