... and 8–10 h) within each treatment, presumably reflecting the time delay necessary for the ornithine–urea cycle to convert the ammonia-N taken up into urea-N ( Wood et al., 1995 ; Nawata et al., 2015a , b ).When these mean 4–10 h urea-N excretion rates were plotted against the same measured seawater...

...), and ammonia transporter Rhcg1 in zebrafish ionocytes responsible for Na + uptake . Front. Physiol.   4 , 59 . Kajimura   M. , Walsh   P. J. , Mommsen   T. P. , Wood   C. M. ( 2006 ). The dogfish shark (Squalus acanthias) increases both hepatic and extrahepatic ornithine urea cycle...

... to significant decreases in the activity of some ornithine–urea cycle enzymes (argininosuccinate synthetase/argininosuccinate lyase and arginase) from the liver of P. sinensis . As a decrease in urea synthesis occurred without the accumulation of ammonia and total free amino acids, it can be deduced that ammonia...

.... Depeche, J., Gilles, R., Daufresne, S. and Chapello, H. ( 1979 ). Urea content and urea production via the ornithine-urea cycle pathway during the ontogenic development of two teleost fishes. Comp. Biochem. Physiol. 63A , 51 -56. Dosdat, F. A. S., Meteailler, R., Huelvan, C. and Desbruyeres,E...

...: Ecosystem Science and Management Program, University of Northern British Columbia, Prince George, BC, Canada V2N 4Z9 23 2 2004 © The Company of Biologists Limited 2004 2004 ornithine–urea cycle arginine urea nitrogen metabolism mitochondrial targeting Oncorhynchus mykiss...

... was excreted in pulsatile events that accounted for 62.0±5.9% of total urea-N excreted. Excretion rates of urea-N and ammonia-N were 1.018±0.084 μmol N h –1 g –1 and 0.235±0.095 μmol N h –1 g –1 ,respectively. Field-collected eggs, larvae and juveniles expressed significant levels of the ornithine–urea cycle...

...Yuen K. Ip; Wai L. Tam; Wai P. Wong; Ai M. Loong; Kum C. Hiong; James S. Ballantyne; Shit F. Chew SUMMARY The white-edge whip tail ray Himantura signifer inhabits a freshwater environment but has retained the capability to synthesize urea de novo through the arginine-ornithine-urea cycle (OUC...

... endogenous ammonia production. Simultaneously, there were significant increases in urea levels in the muscle (8-fold), liver (10.5-fold) and plasma (12.6-fold) of specimens exposed to air for 6 days. Furthermore, there was an increase in the hepatic ornithine-urea cycle (OUC) capacity, with significant...

... the South American freshwater stingray Potamotrygon motoro, H. signifer has a functional ornithine-urea cycle (OUC) in the liver, with hepatic carbamoylphosphate synthetase III (CPS III) and glutamine synthetase (GS) activities lower than those of the marine blue-spotted fan tail ray Taeniura lymma . More...

... mechanism in the gill of the toadfish. * Author for correspondence (e-mail: [email protected] ) 21 1 2003 © The Company of Biologists Limited 2003 2003 glutamine synthetase toadfish ureotely ornithine–urea cycle ammonia detoxification Opsanus beta ammonia excretion...

... of this teleost; uricolysis, argininolysis and the ornithine–urea cycle (OUC). Uricase, allantoinase, allantoicase and ureidoglycollate lyase of the uricolytic pathway were expressed in all early life stages and in adult liver of C. gariepinus . Uricase activity increased in starved larvae compared with yolk-sac...

... in the muscle, skin and gill, but levels were negligible in the liver. Furthermore, all other ornithine–urea cycle (O-UC) enzymes were also detected in muscle, skin and gill. Thus, M. abei clearly shows the transition from ammoniotely to ureotely under ammonia-loading condition and is able to produce urea...

... of Kentucky, Lexington, KY 40506, USA. 28 04 1995 © The Company of Biologists Limited 1995 urea ammonia Opsanus beta ureotelism gills skin urine rectal fluid regurgitation ornithine–urea cycle stress Most teleost fish are obligate ammonioteles excreting the bulk...

... © The Company of Biologists Limited 1995 ammonia urea elasmobranch dogfish Squalus acanthias ornithine–urea cycle gill permeability kidney function nitrogenous waste excretion acid–base balance Since the classic work of Homer Smith (1929 , 1936 ), it has been recognized...

... in normal acid–base regulation. 01 12 1993 © 1994 by Company of Biologists 1994 Lake Magadi urea acid–base balance high pH liver ornithine–urea cycle ammonia glutamine Oreochromis alcalicus grahami The tilapia Oreochromis alcalicus grahami lives in the highly alkaline...

...-to-water ammonia partial pressure diffusion gradient and NH 4 + electrochemical gradient. Urea excretion ( J urea ) almost doubled at 24–48h of pH10 exposure. Activities of ornithine–urea cycle enzymes in the liver were very low and there was no induction at pH10. However, all three enzymes...