{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,30]],"date-time":"2025-07-30T14:05:26Z","timestamp":1753884326644,"version":"3.41.2"},"reference-count":38,"publisher":"The Company of Biologists","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:title>Summary<\/jats:title>\n               <jats:p>The objective of this study was to examine the effects of 6 days of emersion on nitrogen metabolism and excretion in the Chinese soft-shelled turtle, Pelodiscus sinensis. Despite having a soft shell with a cutaneous surface which is known to be water permeable, P. sinensis lost only ~2% of body mass and was able to maintain its hematocrit and plasma osmolality, [Na+] and [Cl-] during 6 days of emersion. During emersion, it ameliorated water loss by reducing urine output, which led to a reduction (by 29-76%) in ammonia excretion. In comparison, there was a more prominent reduction (by 82-99%) in urea excretion during emersion due to a lack of water to flush the buccopharyngeal epithelium, which is known to be the major route of urea excretion. Consequently, emersion resulted in an apparent shift from ureotely to ammonotely in P. sinensis. Although urea concentration increased in several tissues, the excess urea accumulated could only account for 13-22% of the deficit in urea excretion. Hence, it can be concluded that a decrease (~80%) in urea synthesis occurred in P. sinensis during 6 days of emersion. Indeed, emersion led to significant decreases in activities of some ornithine-urea cycle enzymes (argininosuccinate synthetase + argininosuccinate lyase and arginase) from the liver of P. sinensis. Since a decrease in urea synthesis occurred without accumulations of ammonia and total free amino acids, it can be deduced that ammonia production through amino acid catabolism was suppressed with a proportional reduction in proteolysis in P. sinensis during emersion. Indeed, calculated results revealed that there could be a prominent decrease(~88%) in ammonia production in turtles after 6 days of emersion. In summary, despite being ureogenic and ureotelic in water, P. sinensis adopted reduction in ammonia production, instead of increased urea synthesis, as the major strategy to ameliorate ammonia toxicity and problems associated with dehydration during terrestrial exposure.<\/jats:p>","DOI":"10.1242\/jeb.078972","type":"journal-article","created":{"date-parts":[[2013,1,25]],"date-time":"2013-01-25T03:09:10Z","timestamp":1359083350000},"source":"Crossref","is-referenced-by-count":6,"title":["The Chinese soft-shelled turtle, <i>Pelodiscus sinensis<\/i>, decreases nitrogenous excretion, reduces urea synthesis and suppresses ammonia production during emersion"],"prefix":"10.1242","author":[{"given":"Alex Y. K.","family":"Ip","sequence":"first","affiliation":[{"name":"National University of Singapore;"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Serene M. L.","family":"Lee","sequence":"additional","affiliation":[{"name":"National University of Singapore;"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wai P.","family":"Wong","sequence":"additional","affiliation":[{"name":"National University of Singapore;"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Shit F.","family":"Chew","sequence":"additional","affiliation":[{"name":"National Institute of Education, Nanyang Technological University, Singapore"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"237","published-online":{"date-parts":[[2013,1,1]]},"reference":[{"key":"2021042507224370500_R1","doi-asserted-by":"crossref","first-page":"363","DOI":"10.1016\/0010-406X(70)90949-7","article-title":"Comparison of water exchange in two aquatic turtles, Trionyx spinifer and Pseudemys scripta","volume":"32","author":"Bentley","year":"1970","journal-title":"Comp. Biochem. Physiol."},{"key":"2021042507224370500_R2","first-page":"454","article-title":"Ammonia","volume-title":"Methods of Enzymatic Analysis","author":"Bergmeyer","year":"1985"},{"key":"2021042507224370500_R3","first-page":"279","article-title":"Nitrogen excretion","volume-title":"Comparative Animal Physiology","author":"Campbell","year":"1973","edition":"3rd edn"},{"key":"2021042507224370500_R4","first-page":"277","article-title":"Excretory nitrogen metabolism","volume-title":"Comparative Animal Physiology, Environmental and Metabolic Physiology","author":"Campbell","year":"1991"},{"key":"2021042507224370500_R5","first-page":"147","article-title":"Excretory nitrogen metabolism in reptiles and birds","volume-title":"Nitrogen Metabolism and Excretion","author":"Campbell","year":"1995"},{"key":"2021042507224370500_R6","doi-asserted-by":"crossref","first-page":"226","DOI":"10.1086\/319663","article-title":"The loach Misgurnus anguillicaudatus reduces amino acid catabolism and accumulates alanine and glutamine during aerial exposure","volume":"74","author":"Chew","year":"2001","journal-title":"Physiol. Biochem. Zool."},{"key":"2021042507224370500_R7","doi-asserted-by":"crossref","first-page":"693","DOI":"10.1242\/jeb.00140","article-title":"The snakehead Channa asiatica accumulates alanine during aerial exposure, but is incapable of sustaining locomotory activities on land through partial amino acid catabolism","volume":"206","author":"Chew","year":"2003","journal-title":"J. Exp. Biol."},{"key":"2021042507224370500_R8","doi-asserted-by":"crossref","first-page":"3615","DOI":"10.1242\/jeb.00619","article-title":"Urea synthesis in the African lungfish Protopterus dolloi \u2013 hepatic carbamoyl phosphate synthetase III and glutamine synthetase are upregulated by 6 days of aerial exposure","volume":"206","author":"Chew","year":"2003","journal-title":"J. Exp. Biol."},{"key":"2021042507224370500_R9","doi-asserted-by":"crossref","first-page":"777","DOI":"10.1242\/jeb.00813","article-title":"Nitrogen metabolism in the African lungfish (Protopterus dolloi) aestivating in a mucus cocoon on land","volume":"207","author":"Chew","year":"2004","journal-title":"J. Exp. Biol."},{"key":"2021042507224370500_R10","first-page":"307","article-title":"Nitrogen excretion and defense against ammonia toxicity","volume-title":"Fish Physiology","author":"Chew","year":"2005"},{"key":"2021042507224370500_R11","doi-asserted-by":"crossref","first-page":"440","DOI":"10.1152\/physrev.1987.67.2.440","article-title":"Biochemistry and physiology of brain ammonia","volume":"67","author":"Cooper","year":"1987","journal-title":"Physiol. Rev."},{"key":"2021042507224370500_R12","doi-asserted-by":"crossref","first-page":"198","DOI":"10.1152\/ajplegacy.1966.210.1.198","article-title":"Excretion in fresh-water turtle (Pseudemys scripta) and desert tortoise (Gopherus agassizii)","volume":"210","author":"Dantzler","year":"1966","journal-title":"Am. J. Physiol."},{"key":"2021042507224370500_R13","doi-asserted-by":"crossref","first-page":"509","DOI":"10.1016\/0003-9861(72)90170-1","article-title":"The problem of tissue sampling from experimental animals with respect to freezing technique, anoxia, stress and narcosis. A new method for sampling rat liver tissue and the physiological values of glycolytic intermediates and related compounds","volume":"148","author":"Faupel","year":"1972","journal-title":"Arch. Biochem. Biophys."},{"key":"2021042507224370500_R14","doi-asserted-by":"crossref","first-page":"206","DOI":"10.1016\/0010-406X(61)90056-1","article-title":"Aquatic respiration in the common Nile turtle, Trionyx triunguis (Forskal)","volume":"3","author":"Girgis","year":"1961","journal-title":"Comp. Biochem. Physiol."},{"key":"2021042507224370500_R15","first-page":"511","article-title":"Differences in the responses of two mudskippers to terrestrial exposure","volume":"10","author":"Ip","year":"1993","journal-title":"Zoolog. Sci."},{"key":"2021042507224370500_R16","first-page":"109","article-title":"Ammonia toxicity, tolerance and excretion","volume-title":"Fish Physiology","author":"Ip","year":"2001"},{"key":"2021042507224370500_R17","doi-asserted-by":"crossref","first-page":"357","DOI":"10.1007\/s003600100184","article-title":"The sleeper Bostrichthys sinensis (family Eleotridae) stores glutamine and reduces ammonia production during aerial exposure","volume":"171","author":"Ip","year":"2001","journal-title":"J. Comp. Physiol. B"},{"key":"2021042507224370500_R18","doi-asserted-by":"crossref","first-page":"1615","DOI":"10.1242\/jeb.204.9.1615","article-title":"Partial amino acid catabolism leading to the formation of alanine in Periophthalmodon schlosseri (mudskipper): a strategy that facilitates the use of amino acids as an energy source during locomotory activity on land","volume":"204","author":"Ip","year":"2001","journal-title":"J. Exp. Biol."},{"key":"2021042507224370500_R19","doi-asserted-by":"crossref","first-page":"768","DOI":"10.1086\/422057","article-title":"Five tropical air-breathing fishes, six different strategies to defend against ammonia toxicity on land","volume":"77","author":"Ip","year":"2004","journal-title":"Physiol. Biochem. Zool."},{"key":"2021042507224370500_R20","doi-asserted-by":"crossref","first-page":"1993","DOI":"10.1242\/jeb.01586","article-title":"Chronic and acute ammonia toxicity in mudskippers, Periophthalmodon schlosseri and Boleopthalmus boddaerti: brain ammonia and glutamine contents, and effects of methionine sulfoximine and MK801","volume":"208","author":"Ip","year":"2005","journal-title":"J. Exp. Biol."},{"key":"2021042507224370500_R21","doi-asserted-by":"crossref","first-page":"456","DOI":"10.1002\/jez.a.160","article-title":"Changes in salinity and ionic compositions can act as environmental signals to induce a reduction in ammonia production in the African lungfish Protopterus dolloi","volume":"303","author":"Ip","year":"2005","journal-title":"J. Exp. Zool. A"},{"key":"2021042507224370500_R22","doi-asserted-by":"crossref","first-page":"1054","DOI":"10.1002\/jez.a.237","article-title":"The interplay of increased urea synthesis and reduced ammonia production in the African lungfish Protopterus aethiopicus during 46 days of aestivation in a mucus cocoon","volume":"303","author":"Ip","year":"2005","journal-title":"J. Exp. Zool. A."},{"key":"2021042507224370500_R23","doi-asserted-by":"crossref","first-page":"3723","DOI":"10.1242\/jeb.068916","article-title":"The Chinese soft-shelled turtle, Pelodiscus sinensis, excretes urea mainly through the mouth instead of the kidney","volume":"215","author":"Ip","year":"2012","journal-title":"J. Exp. Biol."},{"key":"2021042507224370500_R24","doi-asserted-by":"crossref","first-page":"237","DOI":"10.1242\/jeb.202.3.237","article-title":"The marble goby Oxyeleotris marmoratus activates hepatic glutamine synthetase and detoxifies ammonia to glutamine during air exposure","volume":"202","author":"Jow","year":"1999","journal-title":"J. Exp. Biol."},{"key":"2021042507224370500_R25","first-page":"169","article-title":"Rapid-determination of nitrogen in milk and dairy-products by colorimetric estimation of ammonia following an accelerated digestion procedure","volume":"29","author":"Koops","year":"1975","journal-title":"Neth. Milk Dairy J."},{"key":"2021042507224370500_R26","doi-asserted-by":"crossref","first-page":"995","DOI":"10.1002\/jez.a.350","article-title":"Nitrogen metabolism and excretion in the aquatic chinese soft-shelled turtle, Pelodiscus sinensis, exposed to a progressive increase in ambient salinity","volume":"305","author":"Lee","year":"2006","journal-title":"J. Exp. Zool. A"},{"key":"2021042507224370500_R27","doi-asserted-by":"crossref","first-page":"19","DOI":"10.1007\/s00360-006-0105-8","article-title":"Postprandial increases in nitrogenous excretion and urea synthesis in the Chinese soft-shelled turtle, Pelodiscus sinensis","volume":"177","author":"Lee","year":"2007","journal-title":"J. Comp. Physiol. B"},{"key":"2021042507224370500_R28","doi-asserted-by":"crossref","first-page":"1605","DOI":"10.1242\/jeb.204.9.1605","article-title":"Reduction in the rates of protein and amino acid catabolism to slow down the accumulation of endogenous ammonia: a strategy potentially adopted by mudskippers (Periophthalmodon schlosseri and Boleophthalmus boddaerti) during aerial exposure in constant darkness","volume":"204","author":"Lim","year":"2001","journal-title":"J. Exp. Biol."},{"key":"2021042507224370500_R29","doi-asserted-by":"crossref","first-page":"354","DOI":"10.1002\/jez.a.147","article-title":"Ornithine-urea cycle and urea synthesis in African lungfishes, Protopterus aethiopicus and Protopterus annectens, exposed to terrestrial conditions for 6 days","volume":"303","author":"Loong","year":"2005","journal-title":"J. Exp. Zool. A."},{"key":"2021042507224370500_R30","first-page":"391","article-title":"Reptiles","volume-title":"Comparative Physiology of Osmoregulation in Animals","author":"Minnich","year":"1979"},{"key":"2021042507224370500_R31","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1023\/A:1007745003948","article-title":"The mudskipper Periophthalmodon schlosseri and Boleophthalmus boddaerti can tolerate 446 and 36 \u03bcM of environmental NH3, respectively","volume":"19","author":"Peng","year":"1998","journal-title":"Fish Physiol. Biochem."},{"key":"2021042507224370500_R32","doi-asserted-by":"crossref","first-page":"247","DOI":"10.1002\/jez.1055","article-title":"Negative test for cloacal drinking in a semi-aquatic turtle (Trachemys scripta), with comments on the functions of claocal bursae","volume":"290","author":"Peterson","year":"2001","journal-title":"J. Exp. Zool."},{"key":"2021042507224370500_R33","doi-asserted-by":"crossref","first-page":"1853","DOI":"10.1242\/jeb.205.13.1853","article-title":"Salt and water regulation by the leatherback sea turtle Dermochelys coriacea","volume":"205","author":"Reina","year":"2002","journal-title":"J. Exp. Biol."},{"key":"2021042507224370500_R34","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1016\/0010-406X(66)90184-8","article-title":"The nitrogen excretion of Chelodina longicollis under conditions of hydration and dehydration","volume":"18","author":"Rogers","year":"1966","journal-title":"Comp. Biochem. Physiol."},{"key":"2021042507224370500_R35","doi-asserted-by":"crossref","first-page":"449","DOI":"10.1146\/annurev.ph.39.030177.002313","article-title":"Osmoregulation in amphibians and reptiles","volume":"39","author":"Shoemaker","year":"1977","journal-title":"Annu. Rev. Physiol."},{"key":"2021042507224370500_R36","doi-asserted-by":"crossref","first-page":"2473","DOI":"10.1242\/jeb.00464","article-title":"The swamp eel Monopterus albus reduces endogenous ammonia production and detoxifies ammonia to glutamine during 144 h of aerial exposure","volume":"206","author":"Tay","year":"2003","journal-title":"J. Exp. Biol."},{"key":"2021042507224370500_R37","doi-asserted-by":"crossref","first-page":"1392","DOI":"10.1111\/j.0022-1112.2004.00538.x","article-title":"Nitrogen metabolism and excretion in Allenbatrachus grunniens (L): effects of variable salinity, confinement, high pH and ammonia loading","volume":"65","author":"Walsh","year":"2004","journal-title":"J. Fish Biol."},{"key":"2021042507224370500_R38","doi-asserted-by":"crossref","first-page":"593","DOI":"10.1016\/0300-9629(89)90371-X","article-title":"Aquatic respiration in soft-shelled turtles, Trionyx sinensis","volume":"92A","author":"Wang","year":"1989","journal-title":"Comp. Biochem. Physiol."}],"container-title":["Journal of Experimental Biology"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/journals.biologists.com\/jeb\/article-pdf\/216\/9\/1650\/1874631\/1650.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"http:\/\/journals.biologists.com\/jeb\/article-pdf\/doi\/10.1242\/jeb.078972\/2036107\/jeb_078972.pdf","content-type":"application\/pdf","content-version":"am","intended-application":"syndication"},{"URL":"http:\/\/journals.biologists.com\/jeb\/article-pdf\/doi\/10.1242\/jeb.078972\/2036107\/jeb_078972.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2021,5,18]],"date-time":"2021-05-18T20:29:03Z","timestamp":1621369743000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.biologists.com\/jeb\/article\/doi\/10.1242\/jeb.078972\/257912\/The-Chinese-soft-shelled-turtle-Pelodiscus"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2013,1,1]]},"references-count":38,"URL":"https:\/\/doi.org\/10.1242\/jeb.078972","relation":{},"ISSN":["1477-9145","0022-0949"],"issn-type":[{"type":"electronic","value":"1477-9145"},{"type":"print","value":"0022-0949"}],"subject":[],"published":{"date-parts":[[2013,1,1]]},"article-number":"jeb.078972"}}