Control of glycerol production by rainbow smelt (Osmerus mordax) to provide freeze resistance and allow foraging at low winter temperatures

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DOIResolve DOI: http://doi.org/10.1016/j.cbpc.2004.04.007
AuthorSearch for: ; Search for:
TypeArticle
Journal titleComparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology
Volume139
Issue3
Pages347357; # of pages: 11
Subjectrainbow smelt; Osmerus mordax; glycerol; Glycerol-3-phosphate dehydrogenase; Low temperature; freeze resistance; antifreeze protein; amino; acid metabolism; chemical chaperone
AbstractThe rainbow smelt (Osmerus mordax) is a small anadromous fish that actively feeds under the ice at temperatures as low as the freeze point of seawater. Freezing is avoided through the production of both non-colligative antifreeze protein (AFP) and glycerol that acts in a colligative manner. Glycerol is constantly lost across the gills and skin, thus glycerol production must continue on a sustained basis at low winter temperatures. AFP begins to accumulate in early fall while water temperatures are still high. Glycerol production is triggered when water temperatures decrease to about 5 °C. Glycerol levels rapidly increase with carbon flow from dihydroxyacetone phosphate (DHAP) to glycerol 3-phosphate (G3P) to glycerol. Glucose/glycogen serves as the initial carbon source for glycerol accumulation with amino acids contributing thereafter. The period of glycerol accumulation is associated with increases in GPDH mRNA and PEPCK mRNA followed by elevations in protein synthesis and enzyme activities. Plasma glycerol levels may reach in excess of 500 mM in winter. The high freeze resistance allows rainbow smelt to invade water of low temperature and forage for food. The lower the temperature, the higher the glycerol must be, and the higher the glycerol the greater the loss to the environment through diffusion. During the winter, rainbow smelt feed upon protein rich invertebrates with glycerol production being fueled in part by dietary amino acids via the gluconeogenic pathway. At winter temperatures, glycerol is quantitatively more important than AFP in providing freeze resistance of blood; however, the importance of AFPs to other tissues is yet to be assessed. Glycerol levels rapidly plummet in the spring when water temperature is still close to 0 °C. During this period, freeze resistance must be provided by AFP alone. Overall, the phenomenon of glycerol production by rainbow smelt reveals an elegant connection of biochemistry to ecology that allows this species to exploit an otherwise unavailable food resource.
Publication date
Copyright noticeCopyright 2004 Elsevier Inc. All rights reserved.
LanguageEnglish
AffiliationNRC Institute for Marine Biosciences; National Research Council Canada; Aquatic and Crop Resource Development
Peer reviewedYes
NRC number42410
1338
NPARC number3538279
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Record identifierc4abe058-8625-448e-95c2-3e496f46bd6c
Record created2009-03-01
Record modified2016-05-09
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