Freeze resistance in rainbow smelt (Osmerus mordax): Seasonal pattern of glycerol and antifreeze protein levels and liver enzyme activity associated with glycerol production

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DOIResolve DOI: http://doi.org/10.1086/383509
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TypeArticle
Journal titlePhysiological and Biochemical Zoology
Volume77
Issue3
Pages415422; # of pages: 8
Subjectrainbow smelt; Osmerus mordax; antifreeze proteins
AbstractRainbow smelt (Osmerus mordax) inhabit inshore waters along the North American Atlantic coast. During the winter, these waters are frequently ice covered and can reach temperatures as low as -1.9°C. To prevent freezing, smelt accumulate high levels of glycerol, which lower the freezing point via colligative means, and antifreeze proteins (AFP). The up-regulation of the antifreeze response (both glycerol and AFP) occurs in early fall, when water temperatures are 5°6°C. The accumulation of glycerol appears to be the main mechanism of freeze resistance in smelt because it contributes more to the lowering of the body's freezing point than the activity of the AFP (0.5°C vs. 0.25°C for glycerol and AFP, respectively) at a water temperature of -1.5°C. Moreover, AFP in smelt appears to be a safeguard mechanism to prevent freezing when glycerol levels are low. Significant increases in activities of the liver enzymes glycerol 3-phosphate dehydrogenase (GPDH), alanine aminotransferase (AlaAT), and phosphoenolpyruvate carboxykinase (PEPCK) during the initiation of glycerol production and significant correlations between enzyme activities and plasma glycerol levels suggest that these enzymes are closely associated with the synthesis and maintenance of elevated glycerol levels for use as an antifreeze. These findings add further support to the concept that carbon for glycerol is derived from amino acids.
Publication date
PublisherUniversity of Chicago Press
Copyright noticeCopyright 2004 by the Uiversity of Chicago Press
LanguageEnglish
AffiliationNRC Institute for Marine Biosciences; National Research Council Canada; Aquatic and Crop Resource Development
Peer reviewedYes
NRC number1688
NPARC number3538208
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Record identifier7efa735e-28eb-47ec-b221-1c7c5009d314
Record created2009-03-01
Record modified2016-05-09
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