Linked Life Data

16788033

Source:http://linkedlifedata.com/resource/pubmed/id/16788033

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
Pt 13
pubmed:dateCreated
2006-6-21
pubmed:abstractText
To test the hypothesis that the preference for ketone bodies rather than lipids as oxidative fuel in elasmobranchs evolved in response to the appearance of urea-based osmoregulation, we measured total non-esterified fatty acids (NEFA) in plasma as well as maximal activities of enzymes of intermediary metabolism in tissues from marine and freshwater elasmobranchs, including: the river stingray Potamotrygon motoro (<1 mmol l(-1) plasma urea); the marine stingray Taeniura lymma, and the marine shark Chiloscyllium punctatum (>300 mmol l(-1) plasma urea); and the euryhaline freshwater stingray Himantura signifer, which possesses intermediate levels of urea. H. signifer also were acclimated to half-strength seawater (15 per thousand) for 2 weeks to ascertain the metabolic effects of the higher urea level that results from salinity acclimation. Our results do not support the urea hypothesis. Enzyme activities and plasma NEFA in salinity-challenged H. signifer were largely unchanged from the freshwater controls, and the freshwater elasmobranchs did not show an enhanced capacity for extrahepatic lipid oxidation relative to the marine species. Importantly, and contrary to previous studies, extrahepatic lipid oxidation does occur in elasmobranchs, based on high carnitine palmitoyl transferase (CPT) activities in kidney and rectal gland. Heart CPT in the stingrays was detectable but low, indicating some capacity for lipid oxidation. CPT was undetectable in red muscle, and almost undetectable in heart, from C. punctatum as well as in white muscle from T. lymma. We propose a revised model of tissue-specific lipid oxidation in elasmobranchs, with high levels in liver, kidney and rectal gland, low or undetectable levels in heart, and none in red or white muscle. Plasma NEFA levels were low in all species, as previously noted in elasmobranchs. D-beta-hydroxybutyrate dehydrogenase (d-beta-HBDH) was high in most tissues confirming the importance of ketone bodies in elasmobranchs. However, very low d-beta-HBDH in kidney from T. lymma indicates that interspecific variability in ketone body utilization occurs. A negative relationship was observed across species between liver glutamate dehydrogenase activity and tissue or plasma urea levels, suggesting that glutamate is preferentially deaminated in freshwater elasmobranchs because it does not need to be shunted to urea production as in marine elasmobranchs.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0022-0949
pubmed:author
pubmed:issnType
Print
pubmed:volume
209
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2495-508
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed-meshheading:16788033-Acclimatization, pubmed-meshheading:16788033-Animals, pubmed-meshheading:16788033-Biological Evolution, pubmed-meshheading:16788033-Carnitine O-Palmitoyltransferase, pubmed-meshheading:16788033-Elasmobranchii, pubmed-meshheading:16788033-Energy Metabolism, pubmed-meshheading:16788033-Fatty Acids, Nonesterified, pubmed-meshheading:16788033-Fish Proteins, pubmed-meshheading:16788033-Fresh Water, pubmed-meshheading:16788033-Ketone Bodies, pubmed-meshheading:16788033-Kidney, pubmed-meshheading:16788033-Lipid Metabolism, pubmed-meshheading:16788033-Liver, pubmed-meshheading:16788033-Oceans and Seas, pubmed-meshheading:16788033-Salt Gland, pubmed-meshheading:16788033-Sharks, pubmed-meshheading:16788033-Skates (Fish), pubmed-meshheading:16788033-Sodium Chloride, pubmed-meshheading:16788033-Urea
pubmed:year
2006
pubmed:articleTitle
Metabolic organization of freshwater, euryhaline, and marine elasmobranchs: implications for the evolution of energy metabolism in sharks and rays.
pubmed:affiliation
Department of Integrative Biology, University of Guelph, Guelph, Ontario, NIG 2W1, Canada.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, Non-U.S. Gov't