Glycerol production in rainbow smelt (Osmerus mordax) may be triggered by low temperature alone and is associated with the activation of glycerol-3-phosphate dehydrogenase and glycerol-3-phosphatase

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DOIResolve DOI: http://doi.org/10.1242/jeb.02086
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TypeArticle
Journal titleJournal of Experimental Biology
ISSN0022-0949
1477-9145
Volume209
Issue6
Pages10161023; # of pages: 8
Subjectrainbow smelt; osmerus mordax; glycerol; glycerol-3-phosphate dehydrogenase; glycerol-3-phosphatase; low temperature; freeze resistance
AbstractRainbow smelt (Osmerus mordax) accumulate high levels of glycerol in winter that serves as an antifreeze. Fish were subjected to controlled decreases in water temperature and levels of plasma glycerol, liver metabolites and liver enzymes were determined in order to identify control mechanisms for the initiation of glycerol synthesis. In two separate experiments, decreases in temperature from 8°C to 0°C over a period of 10–11 days resulted in increases in plasma glycerol from levels of less than 4 mmol l⁻¹ to approximate mean levels of 40 (first experiment) and 150 mmol l⁻¹ (second experiment). In a third experiment, decreases in temperature to –1°C resulted in plasma glycerol levels approaching 500 mmol l⁻¹. The accumulation of glycerol could be driven in either December or March, thus eliminating decreasing photoperiod as a necessary cue for glycerol accumulation. Glycerol accumulation in plasma was associated with changes in metabolites in liver leading to increases in the mass action ratio across the reactions catalyzed by glycerol-3-phosphate dehydrogenase (GPDH) and glycerol-3-phosphatase (G3Pase). The maximal, in vitro activity of GPDH, increased twofold in association with a sharp increase in plasma glycerol level. The metabolite levels and enzyme activities provide complementary evidence that GPDH is a regulatory site in the low temperature triggered synthesis of glycerol. Indirect evidence, based on calculated rates of in vivo glycerol production by liver, suggests that G3Pase is a potential rate-limiting step. As well, transient increases in glyceraldehyde-3-phosphate dehydrogenase and alanine aminotransferase suggest that these sites are components of a suite of responses, in rainbow smelt liver, induced by low temperature.
PublisherThe Company of Biologists Ltd.
Copyright notice© The Company of Biologists Ltd 2006
LanguageEnglish
AffiliationNRC Institute for Marine Biosciences; National Research Council Canada
Peer reviewedYes
NRC number55837
1501
NPARC number3538292
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Record identifier9ac23adb-dee2-4026-b0d0-f7c24370a290
Record created2009-03-01
Record modified2016-05-09
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