Functional ureogenesis in the gobiid fish Mugilogobius abei

2000 ◽  
Vol 203 (24) ◽  
pp. 3703-3715 ◽  
Author(s):  
K. Iwata ◽  
M. Kajimura ◽  
T. Sakamoto
Keyword(s):  
Loading Condition ◽  
Urea Cycle ◽  
Sea Water ◽  
Ammonia Solution ◽  
Nitrogen Excretion ◽  
Whole Body ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Gobiid Fish ◽  
N Enrichment

To examine the transition to ureogenesis, the gobiid fish Mugilogobius abei was immersed in 2 mmol l(−)(1) NH(4)HCO(3) or a (15)N-labelled ammonia solution [1 mmol l(−)(1) ((15)NH(4))(2)SO(4), pH 8.0] for 4–8 days. When exposed to 2 mmol l(−)(1) NH(4)HCO(3) or (15)N-labelled ammonia solution for 4 days, the rate of urea excretion increased to seven times that of the control (in 20 % synthetic sea water) and remained at this level for 4 days. The proportion of nitrogen excreted as urea reached 62 % of total nitrogen excretion (ammonia-N + urea-N). (15)N-enrichment of the amide-N in glutamine in the tissues of fish exposed to (15)N-labelled ammonia was virtually the same as that of ammonia-N: i.e. approximately twice that of urea-N in the excreta and the tissues. Glutamine contents and glutamine synthetase activities in the liver and muscle increased greatly following exposure to ammonia. Urea and citrulline contents in the muscle and whole body of the exposed fish increased significantly, whereas uric acid contents remained unchanged. Carbamoyl phosphate synthetase III (CPSase III) mRNA expression and CPSase III activity were detected 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 mainly via the O-UC operating in multiple non-hepatic tissues as a means for ammonia detoxification.

scholarly journals Altered Nitrogen Balance and Decreased Urea Excretion in Male Rats Fed Cafeteria Diet Are Related to Arginine Availability

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
David Sabater ◽  
Silvia Agnelli ◽  
Sofía Arriarán ◽  
José-Antonio Fernández-López ◽  
María del Mar Romero ◽  
...  
Keyword(s):  
Amino Acid ◽  
Urea Cycle ◽  
Cafeteria Diet ◽  
Nitrogen Excretion ◽  
Male Rats ◽  
Synthetase Activity ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Urea Excretion ◽  
Dietary Nitrogen

Hyperlipidic diets limit glucose oxidation and favor amino acid preservation, hampering the elimination of excess dietary nitrogen and the catabolic utilization of amino acids. We analyzed whether reduced urea excretion was a consequence of higherNOx; (nitrite, nitrate, and other derivatives) availability caused by increased nitric oxide production in metabolic syndrome. Rats fed a cafeteria diet for 30 days had a higher intake and accumulation of amino acid nitrogen and lower urea excretion. There were no differences in plasma nitrate or nitrite.NOxand creatinine excretion accounted for only a small part of total nitrogen excretion. Rats fed a cafeteria diet had higher plasma levels of glutamine, serine, threonine, glycine, and ornithine when compared with controls, whereas arginine was lower. Liver carbamoyl-phosphate synthetase I activity was higher in cafeteria diet-fed rats, but arginase I was lower. The high carbamoyl-phosphate synthetase activity and ornithine levels suggest activation of the urea cycle in cafeteria diet-fed rats, but low arginine levels point to a block in the urea cycle between ornithine and arginine, thereby preventing the elimination of excess nitrogen as urea. The ultimate consequence of this paradoxical block in the urea cycle seems to be the limitation of arginine production and/or availability.

scholarly journals Mice deficient in the urea-cycle enzyme, carbamoyl phosphate synthetase i, die during the early neonatal period from hyperammonemia

Hepatology ◽  
1999 ◽  
Vol 29 (1) ◽  
pp. 181-185 ◽  
Author(s):  
J. Paul Schofield ◽  
J. Paul Schofield ◽  
Timothy M. Cox ◽  
C. Thomas Caskey ◽  
Maki Wakamiya
Keyword(s):  
Urea Cycle ◽  
Neonatal Period ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Cycle Enzyme ◽  
Early Neonatal Period ◽  
Urea Cycle Enzyme

scholarly journals SIRT5 Deacetylates Carbamoyl Phosphate Synthetase 1 and Regulates the Urea Cycle

Cell ◽  
2009 ◽  
Vol 137 (3) ◽  
pp. 560-570 ◽  
Author(s):  
Takashi Nakagawa ◽  
David J. Lomb ◽  
Marcia C. Haigis ◽  
Leonard Guarente
Keyword(s):  
Urea Cycle ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Carbamoyl Phosphate Synthetase 1

scholarly journals Adaptation of the carbamoyl-phosphate synthetase enzyme in an extremophile fish

2020 ◽  
Vol 7 (10) ◽  
pp. 201200
Author(s):  
Lewis J. White ◽  
Gemma Sutton ◽  
Asilatu Shechonge ◽  
Julia J. Day ◽  
Kanchon K. Dasmahapatra ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Convergent Evolution ◽  
Urea Cycle ◽  
Substrate Affinity ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Terrestrial Vertebrates ◽  
Terrestrial Vertebrate ◽  
Myogenic Lineage ◽  
Mature Fish

Tetrapods and fish have adapted distinct carbamoyl-phosphate synthase (CPS) enzymes to initiate the ornithine urea cycle during the detoxification of nitrogenous wastes. We report evidence that in the ureotelic subgenus of extremophile fish Oreochromis Alcolapia , CPS III has undergone convergent evolution and adapted its substrate affinity to ammonia, which is typical of terrestrial vertebrate CPS I. Unusually, unlike in other vertebrates, the expression of CPS III in Alcolapia is localized to the skeletal muscle and is activated in the myogenic lineage during early embryonic development with expression remaining in mature fish. We propose that adaptation in Alcolapia included both convergent evolution of CPS function to that of terrestrial vertebrates, as well as changes in development mechanisms redirecting CPS III gene expression to the skeletal muscle.

scholarly journals Role of dexamethasone and insulin on the development of the five urea-cycle enzymes in cultured rat foetal hepatocytes

1985 ◽  
Vol 225 (1) ◽  
pp. 271-274 ◽  
Author(s):  
A Husson ◽  
M Bouazza ◽  
C Buquet ◽  
R Vaillant
Keyword(s):  
Urea Cycle ◽  
Carbamoyl Phosphate Synthetase ◽  
Argininosuccinate Synthetase ◽  
Carbamoyl Phosphate ◽  
Urea Cycle Enzymes

The activity changes of the urea-cycle enzymes were monitored in cultured foetal hepatocytes after dexamethasone and insulin treatments. Addition of dexamethasone induced the development of carbamoyl-phosphate synthetase, argininosuccinate synthetase, argininosuccinase and arginase activities as soon as day 16.5 of gestation. When insulin was added together with dexamethasone, it markedly inhibited the steroid-induced increase in carbamoyl-phosphate synthetase, argininosuccinate synthetase and argininosuccinase activities.

Nitrogen metabolism and excretion in the mangrove killifish Rivulus marmoratus II. Significant ammonia volatilization in a teleost during air-exposure

2002 ◽  
Vol 205 (1) ◽  
pp. 91-100 ◽  
Author(s):  
N. T. Frick ◽  
P. A. Wright
Keyword(s):  
Whole Body ◽  
Carbamoyl Phosphate Synthetase ◽  
Nh3 Volatilization ◽  
Carbamoyl Phosphate ◽  
Air Exposure ◽  
Exposed Fish ◽  
Rivulus Marmoratus ◽  
Body Tissues ◽  
Total Ammonia ◽  
Mangrove Killifish

SUMMARY The mangrove killifish Rivulus marmoratus can tolerate prolonged periods of air-exposure (>1 month). During these periods of emersion, we hypothesized that R. marmoratus would convert potentially toxic ammonia into urea and free amino acids (FAAs). In air-exposed fish, both ammonia (JAmm) and urea (JUrea) excretion continued at approximately 57 % and 39 %, respectively, of submerged rates. Remarkably, approximately 42 % of the total ammonia excreted during air-exposure was through NH3 volatilization. Ammonia did not accumulate in whole-body tissues of air-exposed fish, but levels of both urea and some FAAs (primarily alanine and glutamine) were up to twofold higher after 10 days. The activities of the ornithine–urea cycle enzymes carbamoyl phosphate synthetase III and ornithine transcarbamylase increased (by approximately 30 % and 36 %, respectively) in whole-body tissues of air-exposed fish, while levels of arginase remained unchanged. The activities of enzymes involved in amino acid and oxidative metabolism were not significantly different between control and air-exposed fish. Partitioning of the anterior and posterior ends of immersed fish revealed that just over half (57 %) of the total nitrogen (ammonia+urea) was excreted through the anterior end of the fish, presumably via the branchial tissues, while emersed fish increased excretion via the posterior end (kidney+skin). R. marmoratus do not undergo a shift towards ureotelism during air-exposure. Rather, we propose that R. marmoratus are able to survive on land for extended periods without significant ammonia accumulation because they continuously release ammonia, partially by NH3 volatilization.

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