... at different temperatures (26°C, 30°C and 34°C), before being placed in nutrient-replete or -depleted seawater for 24 h. The corals were then incubated with 13 C-labelled sodium bicarbonate and different 15 N-labelled nitrogen forms (ammonium, urea and dissolved free amino acids) to determine...

... of mammalian sodium/glucose cotransporter 1 ( SGLT1 ) – SGLT1-like – from the ctenidium of the fluted giant clam, Tridacna squamosa . SGLT1-like had a host origin and was expressed predominantly in the ctenidium. Molecular characterizations reveal that SGLT1-like of T. squamosa could transport urea...

...Chris M. Wood; Hon Jung Liew; Gudrun De Boeck; J. Lisa Hoogenboom; W. Gary Anderson ABSTRACT Ureotelic elasmobranchs require nitrogen for both protein growth and urea-based osmoregulation, and therefore are probably nitrogen-limited in nature. Mechanisms exist for retaining and/or scavenging...

...-phosphate, GABA, sugars and polyols). Under HD, signs of oxidative stress were noted but not confirmed at the transcriptional level. Finally, urea, a common metabolic waste, was found to accumulate substantially in food from MD and HD larvae. When supplemented in food, urea stimulated cold tolerance...

...Chris M. Wood; Marina Giacomin ABSTRACT Nitrogen (N) appears to be a limiting dietary resource for elasmobranchs, required not only for protein growth but also for urea-based osmoregulation. Building on recent evidence that the toxicant ammonia can be taken up actively at the gills of the shark...

.... Metabolic rate decreased 20–35% in both species, and gill Na + /K + -ATPase activity was maintained in gummy sharks but decreased 37% in school sharks. We measured plasma ions (Na + , K + , Cl − ) and osmolytes [urea and trimethylamine oxide (TMAO)], and observed a 33% increase in plasma Na + in gummy...

... in this ancient group. We cloned Rh cDNAs ( Rhag, Rhbg and Rhp2 ) and evaluated gill ammonia handling in Squalus acanthias . Control ammonia excretion was <5% of urea-N excretion. Sharks exposed to high environmental ammonia (HEA; 1 mmol −1 NH 4 HCO 3 ) for 48 h exhibited active ammonia uptake against partial...

... 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...

...Jesper Brahm SUMMARY This study extends permeability ( P ) data on chloride, urea and water in red blood cells (RBC), and concludes that the urea transporter (UT-B) does not transport water. P of chick, duck, Amphiuma means , dog and human RBC to 36 Cl − , 14 C-urea and 3 H 2 O was determined under...

...Tamara M. Rodela; M. Danielle McDonald; Patrick J. Walsh; Kathleen M. Gilmour SUMMARY In their native environment, gulf toadfish excrete equal quantities of ammonia and urea. However, upon exposure to stressful conditions in the laboratory (i.e. crowding, confinement or air exposure), toadfish...

... both the expression of Rh isoforms and urea synthesis pathways to tightly control and regulate nitrogen excretion. Although toadfish synthesize urea de novo , a previous study reported that a nitrogen load induced by feeding may exceed the capacity of the ammonia-trapping mechanism in the liver...

... WM by 48 h, and stabilized. Although urea excretion rates ( J Urea ) increased by 2–3-fold during HEA, the increases were insufficient to offset the inhibition of ammonia excretion that occurred, and increases in urea were not observed in the brain or muscle. There was a marked increase in brain...

... were inversely related to energy intake, but they were not related to N intake. By favoring ammonia production over urea, bats on the energy-poor diet may save up to 1% of their basal metabolic rate. Consumption of energy-dilute fruits by fruit bats might affect the way in which N wastes are excreted...

... and gill – including changes in amino acid and inositol (i.e. osmolyte) metabolism, energy metabolism and proteins related to transcription, translation and protein degradation. Overall, leopard sharks employ a strategy of maintaining plasma urea, ion concentrations and Na + /K + -ATPase activities...

...Y. K. Ip; A. M. Loong; B. Ching; G. H. Y. Tham; W. P. Wong; S. F. Chew SUMMARY This study aimed to examine whether the stenohaline freshwater stingray, Potamotrygon motoro , which lacks a functional ornithine—urea cycle, would up-regulate glutamine synthetase (GS) activity and protein abundance...

...Tammy Laberge; Patrick J. Walsh; M. Danielle McDonald SUMMARY The gulf toadfish ( Opsanus beta ) is a facultatively ureotelic fish that excretes primarily urea under conditions of crowding or confinement. To examine the relationship between ammonia production, urea production and the ornithine–urea...

... secretion during digestion). Plasma metabolites (glucose, urea and ammonia) were measured at various time points before and after voluntary feeding to satiation (approximately 5% body mass meal of dry commercial pellets), as was the net flux of ammonia and titratable alkalinity to the water from unfed...

... at all times after feeding. Much of the osmotic equilibration was because of the secretion of urea into the chyme,particularly in the intestine. After feeding, gastric fluid concentrations of Na + and Mg 2+ declined, K + and Ca 2+ increased, whereas Cl – exhibited little change, indicating...

... individual free AA concentrations as indicated by variable ratios among the simultaneous blood samples. Furthermore, the elevation of ammonium and urea in the HPV indicates intestinal catabolism of ingested free AA before release into the HPV. In conclusion, the dual HPV and DA cannulation shows promise...

... synthetase I or III activity was detected in its liver. It was ammonotelic in water, and did not detoxify ammonia through increased urea synthesis during the 4 days of emersion. Unlike many air-breathing fishes reported elsewhere, A. testudineus could uniquely excrete ammonia during emersion at a rate...