tailieunhanh - Báo cáo khoa học: Mechanisms of accumulation of arachidonate in phosphatidylinositol in yellowtail A comparative study of acylation systems of phospholipids in rat and the fish species Seriola quinqueradiata

It is known that phosphatidylinositol (PtdIns) contains abundant arachidonate and is composed mainly of 1-stea-royl-2-arachidonoyl species in mammals. We investigated if this characteristic of PtdIns applies to the PtdIns from yellowtail (Seriolaquinqueradiata),amarinefish. Incommon with phosphatidylcholine (PtdCho),phosphatidylethanol-amine (PtdEtn) andphosphatidylserine (PtdSer) frombrain, heart,liver,spleen,kidney and ovary,the predominant polyunsaturated fatty acid was docosahexaenoic acid,and levels of arachidonic acid were less than (PtdCho), (PtdEtn) (PtdSer) in these tissues | Eur. J. Biochem. 270 1466-1473 2003 FEBS 2003 doi Mechanisms of accumulation of arachidonate in phosphatidylinositol in yellowtail A comparative study of acylation systems of phospholipids in rat and the fish species Seriola quinqueradiata Tamotsu Tanaka Dai Iwawaki Masahiro Sakamoto Yoshimichi Takai Jun-ichi Morishige Kaoru Murakami and Kiyoshi Satouchi Department of Applied Biological Science Fukuyama University Japan It is known that phosphatidylinositol PtdIns contains abundant arachidonate and is composed mainly of 1-stea-royl-2-arachidonoyl species in mammals. We investigated if this characteristic of PtdIns applies to the PtdIns from yellowtail Seriola quinqueradiata a marine fish. In common with phosphatidylcholine PtdCho hhoshhaddylethnnol-amine PtdEtn and phosphatidylserine PtdSer from brain heart liver spleen kidney and ovary the predominant polyunsaturated fatty acid was docosahexaenoic acid and levels of arachidonic acid were less than PtdCho PtdEtn and PtdSer in these tissues. In striking contrast anu lidoniK. acid made up and of the fatty acid compoiiiion of PtdIns from brain heart liver spleen kidney and ovary respectively. The most abundant molecular species of PtdIns in all these tissues was 1-stearoyl-2-arachidonoyl. Assay of acyltransferase in liver microsomes of yellowtail showed that arachidonic acid was incorporated into PtdIns more effectively than docosahexaenoic acid and that the latter inhibited incorporation of arachidonic acid into PtdCho without inhibiting the utilization of arachidonic acid for PtdIns. This effect of docosahexaenoic acid was not observed in similar experiments using rat liver microsomes and is thought to contribute to the exclusive utilization of arachidonic acid for acylation to PtdIns in yellowtail. Inositolphospholipids and their hydrolysates are known to act as signaling molecules in cells. The conserved hydrophobic structure of PtdIns the