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The biosynthesis of docosahexaenoic acid [22:6(n‐3)] from linolenic acid in primary hepatocytes isolated from wild northern pike
Author(s) -
Buzzi M.,
Henderson R. J.,
Sargent J. R.
Publication year - 1997
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1997.tb01136.x
Subject(s) - biology , docosahexaenoic acid , pike , biosynthesis , linolenic acid , biochemistry , alpha linolenic acid , zoology , fatty acid , fishery , fish <actinopterygii> , polyunsaturated fatty acid , gene , linoleic acid
Primary hepatocytes from wild northern pike Esox lucius were incubated with radiolabelled linolenic acid ([l‐ 14 C]‐18:3(n‐3)) to assess their ability to synthesize docosahexaenoic acid [22:6(n‐3)]. The distribution of radioactivity in lipid classes and hepatocyte polyunsaturated fatty acids (PUFA) was measured over the time‐course of 24h. The majority of radioactivity from [l‐ 14 C]‐18:3(n‐3) was recovered in hepatocyte triacylglycerols (TAG) and phosphatidylcholine (PC). The levels of radioactivity in TAG and in most of phospholipids, including PC, increased significantly over the incubation period. Radioactivity from [1‐ 14 C]‐18:3(n‐3) was recovered in several hepatocyte PUFA, including 22:6(n‐3), and the Δ6 and Δ5‐desaturation products 18:4(n‐3) and 20:5(n‐3). The presence of radioactivity in C 24 (n‐3) PUFA may be evidence that the biosynthesis of 22:6(n‐3) in pike proceeds via a pathway independent of Δ4‐desaturation. Analysis by radio gas chromatography revealed that radiolabelled 24:6(n‐3) was present among the desaturation and elongation products of [l‐ 14 C]‐18:3(n‐3). The results establish that, under the in vitro conditions employed, pike hepatocytes are able to convert linolenic acid to 20:5(n‐3) and 22:6(n‐3).