Journal ArticleDOI
The dogfish shark (Squalus acanthias) increases both hepatic and extrahepatic ornithine urea cycle enzyme activities for nitrogen conservation after feeding.
Makiko Kajimura,Patrick J. Walsh,Patrick J. Walsh,Thomas P. Mommsen,Thomas P. Mommsen,Chris M. Wood,Chris M. Wood,Chris M. Wood +7 more
TLDR
It is suggested that N conservation is a high priority in this elasmobranch and that feeding promotes ureogenesis and growth.Abstract:
Urea not only is utilized as a major osmolyte in marine elasmobranchs but also constitutes their main nitrogenous waste. This study investigated the effect of feeding, and thus elevated nitrogen intake, on nitrogen metabolism in the Pacific spiny dogfish Squalus acanthias. We determined the activities of ornithine urea cycle (O‐UC) and related enzymes in liver and nonhepatic tissues. Carbamoyl phosphate synthetase III (the rate‐limiting enzyme of the O‐UC) activity in muscle is high compared with liver, and the activities in both tissues increased after feeding. The contribution of muscle to urea synthesis in the dogfish body appears to be much larger than that of liver when body mass is considered. Furthermore, enhanced activities of the O‐UC and related enzymes (glutamine synthetase, ornithine transcarbamoylase, arginase) were seen after feeding in both liver and muscle and were accompanied by delayed increases in plasma urea, trimethylamine oxide, total free amino acids, alanine, and chloride ...read more
Citations
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Journal ArticleDOI
Osmoregulation and excretion
Erik Larsen,Lewis E. Deaton,Horst Onken,Michael P. O'Donnell,Martin Grosell,William H. Dantzler,Dirk Weihrauch +6 more
TL;DR: How knowledge in these areas of comparative physiology has expanded considerably during the last two decades is demonstrated, bridging seminal classical works with studies based on new approaches at all levels of anatomical and functional organization.
Journal ArticleDOI
Osmoregulation, ionoregulation and acid-base regulation by the gastrointestinal tract after feeding in the elasmobranch (Squalus acanthias).
Chris M. Wood,Makiko Kajimura,Makiko Kajimura,Carol Bucking,Carol Bucking,Patrick J. Walsh,Patrick J. Walsh,Patrick J. Walsh +7 more
TL;DR: The results illustrate the complex integration of digestive and ionoregulatory function in the elasmobranch digestive tract, and marked differences from the teleost pattern.
Journal ArticleDOI
The physiology and evolution of urea transport in fishes
TL;DR: It is believed that the facilitated diffusion urea transporter (UT) gene family has undergone major evolutionary changes, likely in association with the role of urea transport in the evolution of terrestriality in the vertebrates.
Journal ArticleDOI
The influence of feeding and fasting on plasma metabolites in the dogfish shark (Squalus acanthias).
Chris M. Wood,Patrick J. Walsh,Patrick J. Walsh,Patrick J. Walsh,Makiko Kajimura,Makiko Kajimura,Makiko Kajimura,Grant B. McClelland,Grant B. McClelland,Shit F. Chew +9 more
TL;DR: These data are interpreted in light of companion studies showing elevations in aerobic metabolic rate, urea production, rectal gland function, metabolic base excretion, and activation of ornithine-urea cycle and aerobic enzymes after the meal, and muscle N-depletion but maintenance of osmolality and ureaproduction during long-term fasting.
Journal ArticleDOI
The alkaline tide goes out and the nitrogen stays in after feeding in the dogfish shark, Squalus acanthias
Chris M. Wood,Carol Bucking,Carol Bucking,John L. Fitzpatrick,Sunita R. Nadella,Sunita R. Nadella +5 more
TL;DR: Results, which differ greatly from those in teleost fish, are interpreted in terms of the fundamentally different ureotelic osmoregulatory strategy of elasmobranchs, and recent discoveries on base excretion and urea-retention mechanisms in elasmOBranch gills.
References
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A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding
TL;DR: This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr with little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose.
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Ammonia determination based on indophenol formation with sodium salicylate
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Standardized diet compositions and trophic levels of sharks
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Amino acid analysis: aqueous dimethyl sulfoxide as solvent for the ninhydrin reaction.
TL;DR: Dimethyl sulfoxide can replace the latter, volume for volume, in a ninhydrin reagent mixture that gives equal performance and has improved stability, and is recommended to replace methyl Cellosolve-containing reagents in the quantitative determination of amino acids by automatic analyzers and by the manual ninHydrin method.
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Improvements in the determination of urea using diacetyl monoxime; methods with and without deproteinisation
TL;DR: The sensitivity of the colorimetric reaction and stability of the colour are enhanced over existing related procedures and the serum blank diminished, enabling urea to be precisely measured in micro amounts (1--5 microliters) of serum.