MOLECULAR SPECIATION OF FISH SPERM PHOSPHOLIPIDS - LARGE AMOUNTS OF DIPOLYUNSATURATED PHOSPHATIDYLSERINE

The molecular species compositions of the main diacyl phosphoglyceride classes and ether-linked subclasses from sperm of three species of fi sh, sea bass Dicentrarchus labrax, Atlantic salmon Salmo salar and Chi nook salmon Onchorhynchus tsawytscha, were determined. The phospholipi ds from sperm were highly unsaturated, dipolyunsaturated fatty acid (d iPUFA) molecular species comprised 64.6 to 71.8% of phosphatidylserine (PS), 10.1 to 17.4% of phosphatidylethanolamine (PE), and 3.3 to 10.1 % of phosphatidylcholine (PC). In sea bass sperm, di22:6n-3 phospholip id was the predominant diPUFA molecular species, but in both salmon sp ecies 22:5n-3/22:6n-3 was also a major constituent of PS. Phospholipid s containing 22:6n-3 dominated in sea bass sperm with 16:0/22:6n-3 as a major component of PC and PE, and 18:0/22:6n-3 of PE and PS in addit ion to di22:6n-3 in the latter two classes. In contrast, both salmon s pecies contained much more 20:5n-3 and less 22:6n-3 so that saturated/ 20:5n-3 and monounsaturated/20:5n-3 molecular species were more abunda nt than the corresponding molecules containing 22:6n-3. Ether-linked l ipids comprised 11.3-36.3% of choline and ethanolamine phosphoglycerid es in each fish species. Molecular species containing 22:6n-3 were the major components of 1-O-alkyl-2-acyl-glycerophosphocholine, especiall y 16:0a/22:6n-3 in sea bass and 18:1a/22:6n-3 in the two salmon specie s, while in 1-O-alk-1'-enyl-2-acyl-glycerophosphoethanolamine, 1:6:0a/ 22:6n-3 was the major component in both salmon and 18:0a/22:6n-3 in se a bass with 18:1a/22:6n-3 abundant in all three species. In Atlantic s almon 1-O-alkyl-2-acylglycerophosphoethanolamine comprised 24.6% of et hanolamine glycerophospholipids which were predominantly 16:0a/22:6n-3 and 18:1a/22:6n-3. Phosphatidylinositol from sperm was dominated by s tearoyl/C-20 PUFA molecular species, in sea bass overwhelmingly 18:0/2 0:4n-6, while in both salmon species 18:0/20:4n-6 and 18:0/20:5n-3 wer e equally abundant.