Cloning of glycerol-3-phosphate dehydrogenase cDNAs from two fish species and effect of temperature on enzyme expression in rainbow smelt (Osmerus mordax).
Rainbow smelt (Osmerus mordax) can accumulate extreme levels of glycerol in their blood during winter. Low temperatures are required for glycerol accumulation in smelt blood and the enzyme glycerol-3-phosphate dehydrogenase (GPDH) has been suggested to play a role in glycerol production/concentration in this species. In the present study, cDNA sequences encoding glycerol-3-phosphate dehydrogenase (GPDH) from rainbow smelt and Atlantic salmon (Salmo salar) were cloned. The encoded GPDH protein sequences were very similar to one another (88% identity). Using RT-PCR, GPDH mRNA was detected in skin, gill, heart, head kidney, brain and liver from both salmon and smelt obtained in December. However, GPDH was not detected in salmon intestine and spleen or in smelt intestine. Examination of GPDH expression in smelt liver during February by Northern blotting revealed temperature regulation. Elevation of the temperature resulted in a significant decrease in liver GPDH transcript level. Serum glycerol levels decreased concomitantly. These findings suggest a role for GPDH in the accumulation of glycerol in smelt at low temperatures.
NRC Institute for Marine Biosciences, 1411 Oxford St., Halifax, NS Canada B3H 3Z1. vanya.ewart@nrc.ca
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Ewart
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Richards
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Driedzic
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D003001:Cloning, Molecular; D003080:Cold Temperature; D017931:DNA Primers / Q000737:chemistry; D018076:DNA, Complementary / Q000235:genetics; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000235:genetics* / Q000378:metabolism*; D005990:Glycerol / Q000097:blood; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020317:Salmo salar / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D020080:Tandem Repeat Sequences; D014018:Tissue Distribution
D017931:DNA Primers; D018076:DNA, Complementary; D012333:RNA, Messenger; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D005990:Glycerol