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Bucking C, LeMoine CMR, Craig PM, Walsh PJ. Nitrogen metabolism of the intestine during digestion in a teleost fish, the plainfin midshipman (Porichthys notatus). ACTA ACUST UNITED AC 2013; 216:2821-32. [PMID: 23619402 DOI: 10.1242/jeb.081562] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Digestion affects nitrogen metabolism in fish, as both exogenous and endogenous proteins and amino acids are catabolized, liberating ammonia in the process. Here we present a model of local detoxification of ammonia by the intestinal tissue of the plainfin midshipman (Porichthys notatus) during digestion, resulting in an increase in urea excretion of gastrointestinal origin. Corroborating evidence indicated whole-animal ammonia and urea excretion increased following feeding, and ammonia levels within the lumen of the midshipman intestine increased to high levels (1.8±0.4 μmol N g(-1)). We propose that this ammonia entered the enterocytes and was detoxified to urea via the ornithine-urea cycle (O-UC) enzymes, as evidenced by a 1.5- to 2.9-fold post-prandial increase in glutamine synthetase activity (0.14±0.05 and 0.28±0.02 μmol min(-1) g(-1) versus 0.41±0.03 μmol min(-1) g(-1)) and an 8.7-fold increase in carbamoyl phosphate synthetase III activity (0.3±1.2 versus 2.6±0.4 nmol min(-1) g(-1)). Furthermore, digestion increased urea production by isolated gastrointestinal tissue 1.7-fold, supporting our hypothesis that intestinal tissue synthesizes urea in response to feeding. We further propose that the intestinal urea may have been excreted into the intestinal lumen via an apical urea transporter as visualized using immunohistochemistry. A portion of the urea was then excreted to the environment along with the feces, resulting in the observed increase in urea excretion, while another portion may have been used by intestinal ureolytic bacteria. Overall, we propose that P. notatus produces urea within the enterocytes via a functional O-UC, which is then excreted into the intestinal lumen. Our model of intestinal nitrogen metabolism does not appear to be universal as we were unab le to activate the O-UC in the intestine of fed rainbow trout. However, literature values suggest that multiple fish species could follow this model.
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Affiliation(s)
- Carol Bucking
- Department of Biology, University of Ottawa, ON, Canada and Bamfield Marine Science Center, Bamfield, BC, Canada.
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Andersen Ø, Aas TS, Skugor S, Takle H, van Nes S, Grisdale-Helland B, Helland SJ, Terjesen BF. Purine-induced expression of urate oxidase and enzyme activity in Atlantic salmon (Salmo salar). Cloning of urate oxidase liver cDNA from three teleost species and the African lungfish Protopterus annectens. FEBS J 2006; 273:2839-50. [PMID: 16759232 DOI: 10.1111/j.1742-4658.2006.05288.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The peroxisomal enzyme urate oxidase plays a pivotal role in the degradation of purines in both prokaryotes and eukaryotes. However, knowledge about the purine-induced expression of the encoding gene is lacking in vertebrates. These are the first published sequences of fish urate oxidase, which were predicted from PCR amplified liver cDNAs of Atlantic salmon (Salmo salar), Atlantic cod (Gadus morhua), Atlantic halibut (Hippoglossus hippoglossus) and African lungfish (Protopterus annectens). Sequence alignment of different vertebrate urate oxidases revealed amino acid substitutions of putative functional importance in the enzyme of chicken and lungfish. In the adult salmon, expression of urate oxidase mRNA predominated in liver, but was also identified in several nonhepatic organs including brain, but not in skeletal muscle and kidney. Juvenile salmon fed diets containing bacterial protein meal (BPM) rich in nucleic acids showed a significant increase in liver urate oxidase enzyme activity, and urea concentrations in plasma, muscle and liver were elevated. Whereas salmon fed the 18% BPM diet showed a nonsignificant increase in liver mRNA levels of urate oxidase compared with the 0% BPM-fed fish, no further increase in mRNA levels was found in fish receiving 36% BPM. The discrepancy between urate oxidase mRNA and enzyme activity was explained by rapid mRNA degradation or alternatively, post-translational control of the activity. Although variable plasma and liver levels of urate were detected, the substrate increased only slightly in 36% BPM-fed fish, indicating that the uricolytic pathway of Atlantic salmon is intimately regulated to handle high dietary purine levels.
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Affiliation(s)
- Øivind Andersen
- AKVAFORSK, Institute of Aquaculture Research AS, As, Norway.
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Terjesen BF, Chadwick TD, Verreth JA, Rønnestad I, Wright PA. Pathways for urea production during early life of an air-breathing teleost, the African catfish Clarias gariepinus Burchell. J Exp Biol 2001; 204:2155-65. [PMID: 11441057 DOI: 10.1242/jeb.204.12.2155] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Embryos and larvae of the African catfish Clarias gariepinus excrete significant quantities of urea. The present study focused on the potential urea-generating pathways during early development 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 larvae. The key regulatory enzyme of the teleost OUC, carbamoyl phosphate synthetase III (CPSase III), was expressed predominantly in muscle of developing C. gariepinus larvae and showed negligible activity in the absence of its allosteric effector N-acetyl-l-glutamate. CPSase III and ornithine carbamoyl transferase activities increased in fed larvae compared with starved larvae. In contrast to the early developmental stages, adult C. gariepinus expressed only low and variable levels of CPSase III, suggesting that, under the experimental conditions employed, OUC expression is influenced by developmental stage in this species. The data indicate that early C. gariepinus life stages express the enzymes necessary for urea production by uricolysis, argininolysis and the OUC, and this may explain why urea tissue levels and urea excretion rates are substantial during the early development of this air-breathing teleost.
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Affiliation(s)
- B F Terjesen
- Department of Zoology, University of Bergen, Allègaten, 41, N-5007 Bergen, Norway.
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Anderson PM. Urea and glutamine synthesis: Environmental influences on nitrogen excretion. FISH PHYSIOLOGY 2001. [DOI: 10.1016/s1546-5098(01)20008-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Abstract
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.
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Affiliation(s)
- K Iwata
- Biological Laboratory, Faculty of Education, Wakayama University, Wakayama 640-8510, Japan.
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Abstract
Teleosts appear to have retained the genes for the urea cycle enzymes. A few species express the full complement of enzymes and are ureotelic (e.g., Lake Magadi tilapia) or ammoniotelic (e.g., largemouth bass), whereas most species have low or non-detectable enzyme activities in liver tissue and excrete little urea (e.g., adult rainbow trout). It was surprising, therefore, to find the expression of four urea cycle enzymes during early life stages of rainbow trout. The urea cycle may play a role in ammonia detoxification during a critical time of development. Exposure to alkaline water (pH 9.0-9.5) or NH4Cl (0.2 mmol/l) increased urea excretion by several-fold in trout embryos, free embryos and alevin. Urea transport is either by passive simple diffusion or via carried-mediated transport proteins. Molecular studies have revealed that a specialised urea transport protein is present in kidney tissue of elasmobranchs, similar to the facilitated urea transporter found in the mammalian inner medulla of the kidney.
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Affiliation(s)
- P A Wright
- Department of Zoology, University of Guelph, Ontario, Canada.
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Wright PM, Wright PA. Nitrogen Metabolism and Excretion in Bullfrog (Rana catesbelana) Tadpoles and Adults Exposed to Elevated Environmental Ammonia Levels. ACTA ACUST UNITED AC 1996. [DOI: 10.1086/physzool.69.5.30164246] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Chapter 18 Estivation: Mechanisms and control of metabolic suppression. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s1873-0140(06)80044-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Randall DJ, Wood CM, Perry SF, Bergman H, Maloiy GM, Mommsen TP, Wright PA. Urea excretion as a strategy for survival in a fish living in a very alkaline environment. Nature 1989; 337:165-6. [PMID: 2911349 DOI: 10.1038/337165a0] [Citation(s) in RCA: 178] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Ammonia is toxic to all vertebrates. It can be converted to the less toxic urea, but this is a metabolically expensive process found only in terrestrial vertebrates that cannot readily excrete ammonia and marine fish that use urea as an osmotic filler. Freshwater fish mostly excrete ammonia with only a small quantity of urea. It seems the ornithine cycle for urea production has been suppressed in all freshwater teleosts except for some airbreathers which, when exposed to air, increase urea synthesis via the cycle. Here we show that the tilapia fish Oreochromis alcalicus grahami, the only fish living in Lake Magadi, an alkaline soda lake (pH = 9.6-10) in the Kenyan Rift Valley, excretes exclusively urea and has ornithine-urea cycle enzymes in its liver. A closely related species that lives in water at pH 7.1 lacks these enzymes and excretes mainly ammonia with small amounts of urea produced via uricolysis. It dies within 60 min when placed in water from Lake Magadi. We suggest that urea production via the ornithine-urea cycle permits O. a. grahami to survive the very alkaline conditions in Lake Magadi.
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Affiliation(s)
- D J Randall
- Department of Animal Physiology, Veterinary College, University of Nairobi, Kenya
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Saha N, Ratha BK. Active ureogenesis in a freshwater air-breathing teleost,Heteropneustes fossilis. ACTA ACUST UNITED AC 1987. [DOI: 10.1002/jez.1402410117] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Goldenberg H. Organization of purpine degradation in the liver of a teleost (carp; Cyprinus carpio L.). A study of its subcellular distribution. Mol Cell Biochem 1977; 16:17-21. [PMID: 18664 DOI: 10.1007/bf01769834] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Carp liver was fractionated by differential and density gradient centrifugation and assayed for enzymes of purine catabolism. While urate oxidase is an exclusively peroxisomal enzyme, only a very small percentage of the enzymes xanthine oxidase, allantoinase and allantoicase is associated with subcellular or ganelle fractions. There is no general purine catabolizing subcellular compartment. There is some but not yet conclusive evidence for the assumption that urate oxidase is a membrane bound enzyme.
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Gregory R. Synthesis and total excretion of waste nitrogen by fish of the periophthalmus (mudskipper) and scartelaos families. ACTA ACUST UNITED AC 1977. [DOI: 10.1016/0300-9629(77)90344-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Vogels GD, Van der Drift C. Degradation of purines and pyrimidines by microorganisms. BACTERIOLOGICAL REVIEWS 1976; 40:403-68. [PMID: 786256 PMCID: PMC413962 DOI: 10.1128/br.40.2.403-468.1976] [Citation(s) in RCA: 255] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Andrews TR, Reid RG. Ornithine cycle and uricolytic enzymes in four bivalve molluscs. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1972; 42:475-91. [PMID: 4644218 DOI: 10.1016/0305-0491(72)90263-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Scott PJ, Visentin LP, Allen JM. The enzymatic characteristics of peroxisomes of amphibian and avian liver and kidney. Ann N Y Acad Sci 1969; 168:244-64. [PMID: 4393703 DOI: 10.1111/j.1749-6632.1969.tb43113.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Nitrogneous waste products and excretory enzymes in the marine polychaete Cirriformia spirabrancha (Moore, 1904). ACTA ACUST UNITED AC 1969. [DOI: 10.1016/0010-406x(69)92164-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Cvancara VA. Distribution of liver allantoinase and allantoicase activity in fresh-water teleosts. ACTA ACUST UNITED AC 1969. [DOI: 10.1016/0010-406x(69)91614-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Lockwood GF, Garrison RG. The possibel role of uric acid in the ecology of Histoplasma capsulatum. MYCOPATHOLOGIA ET MYCOLOGIA APPLICATA 1968; 35:377-88. [PMID: 5696730 DOI: 10.1007/bf02050753] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Mounib MS, Eisan JS. Carbon dioxide fixation by spermatozoa of cod. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY 1968; 25:703-9. [PMID: 5653723 DOI: 10.1016/0010-406x(68)90380-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Janssens PA, Cohen PP. Biosynthesis of urea in the estivating African lungfish and in Xenopus laevis under conditions of water-shortage. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY 1968; 24:887-98. [PMID: 5650496 DOI: 10.1016/0010-406x(68)90800-1] [Citation(s) in RCA: 90] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Watts DC. Variation in enzyme structure and function: the guidelines of evolution. ADVANCES IN COMPARATIVE PHYSIOLOGY AND BIOCHEMISTRY 1968; 3:1-114. [PMID: 4874872 DOI: 10.1016/b978-0-12-395512-8.50007-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Abstract
Urea occurs in liver of the coelacanth Latimeria chalumnae to the extent of about 1.7 percent by weight. It was determined quantitatively by reaction with 1-phenyl-1,2-propanedione-2-oxime (Archibald reagent) and by measurement of ammonia released upon treatment with urease. Arginase and ornithine carbamoyltransferase, enzymes instrumental in the formation of urea in typical ureotelic vertebrates, occur in homogenates of coelacanth liver. Formed in part by the ornithine-urea cycle, urea may have an osmoregulatory function in the coelacanth as it has in elasmobranchs.
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Pickford GE, Grant FB. Serum osmolality in the coelacanth, Latimeria chalumnae: urea retention and ion regulation. Science 1967; 155:568-70. [PMID: 6015871 DOI: 10.1126/science.155.3762.568] [Citation(s) in RCA: 51] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Samples of blood (hemolyzed) were obtained from the renal vein, the hepatic portal vein, and the heart of a freshly thawed specimen of Latimeria chalumnae. The coelacanth uses high concentrations of urea to maintain its serum osmolality at approximately that of sea water. The mean value for the total osmolality was 1181 milliosmoles per liter. The mean values (milliequivalents per liter) were: for sodium, 181; for potassium, 51.3; for calcium, 6.9; for magnesium, 28.7; for chloride, 199; and for bicarbonate, 4.7. The mean urea concentration was 355 millimoles per liter, and the mean nonprotein nitrogen was 1343 milligrams percent. Heart blood showed significantly lower values for osmolality (921 milliosmoles per liter) and nonprotein nitrogen (1030 mg percent) and was probably less severely contaminated with products of protein breakdown. Fluid from the anterior chamber of the eye showed values of 952 milliosmole/liter; the urea value for this fluid was 303 mmole/liter, and the magnesium was 7.3 meq/liter. The magnesium value for the aqueous humor was used to correct the abnormally high concentrations in the hemolyzed serum. The high level of serum potassium also was attributed to hemolysis.
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