Seasonal dynamics of fatty acid composition in female northern pike (Esox lucius L.)

Abstract

Abstract. Seasonal changes in the fatty acid composition of neutral and polar lipids were measured in the ovary, liver, white muscle, and adipopancreatic tissue of northern pike. The role of environmental and physiological factors underlying these changes was evaluated. From late summer (August-September) to winter (JanuaryMarch), the weight percentage of n-3 polyunsaturated fatty acids (especially 22: 6n3) declined significantly in the neutral lipids of all somatic tissues examined. However, large quantities of n-3 polyunsaturated fatty acids accumulated in the recrudescing ovaries during fall and the weight percentage of n-3 polyunsaturated fatty acids in ovary polar lipids also increased significantly. Additionally, the n-3 polyunsaturated fatty acid content of somatic polar lipids increased significantly during fall due to increases in the total polar lipid content of the somatic tissues. This suggests that during fall n-3 polyunsaturated fatty acid, are diverted away from somatic neutral lipids and thereby conserved for use in ovary construction and for incorporation into tissue polar lipids. The percentage of n-3 polyunsaturated fatty acid in ovary neutral lipids also declined during fall and early winter, perhaps as an adaptation to conserve these fatty acids for storage in oocyte polar lipids and later incorporation into cellular membranes of the developing embryo. Reductions in the n-3 polyunsaturated fatty acids content of somatic and ovarian neutral lipids during fall were compensated for specifically by increases in the percentage of monounsaturated fatty acids rather than saturated fatty acids. This suggests that the ratio of saturated to unsaturated fatty acids in pike neutral lipid, is regulated physiologically, and hence may influence the physiological functioning of these lipids. During fall and early winter the percentage of saturated fatty acids declined significantly in the polar Abbreviations: AP, adipopancreatic; BHT, butylated hydroxytoluene; CI, confidence interval; EFA, essential fatty acids; MUFA, monounsaturated fatty acids; NL, neutral lipids; PL, polar lipids; PUFA, polyunsaturated fatty acids; SFA, saturated fatty acids Correspondence to: K. Schwalme, Alberta Environmental Centre, Bag 4000, Vegreville, Alberta, Canada, TOB-4L0 lipids of all tissues examined. This change was consistent with the known effects of cold acclimation on the fatty acid composition of cellular membranes. As the ovaries were recrudescing from September to January, liver polar lipids exhibited significant decreases in the percentage of total polyunsaturated fatty acids and n-3 polyunsaturated fatty acids and increases in monounsaturated fatty acids, and acquired a fatty acid composition very similar to that of ovary polar lipids. Therefore, seasonal changes in the percentage of polyunsaturated and monounsaturated fatty acids in liver polar lipids probably reflect the liver's role in vitellogenesis rather than the effects of temperature on membrane fatty acid composition. At all times of year, the fatty acid com...

Composition, accumulation and utilization of yolk lipids in teleost fish

“…For example, in rainbow trout, 2 the relative abundance of ovarian phospholipids increases compared with that of TAGs during ovarian development (Kaitaranta and Ackman, 1981;Wiegand and Idler, 1982;Riazi and Fremont, 1988;Nassour and L6ger, 1989). Steady changes in proportions of individual fatty acids have been observed by repeated sampling throughout ovarian development in Baltic herring (Kaitaranta and Linko, 1984), landlocked Atlantic salmon (Wiegand and Idler, 1985) and northern pike (Schwalme et al, 1993).…”

“…Proportions of (n-6) fatty acids were higher in lipoprotein yolk or polar lipids of wild freshwater species (Table 3), for example walleye and northern pike, but still much less than those of (n-3) PUFA. A more significant structural role for (n-6) PUFA in freshwater fish embryos is suggested by the higher (n-6) proportions in both the eggs and the tissue phospholipids of these fish compared with marine species (Ackman and Takeuchi, 1986;Schwalme et al, 1993). In addition to any structural function, a prominent role of AA in vertebrates is as a precursor for a variety of intracellular and extracellular messengers collectively known as eicosanoids.…”

The desaturation and elongation of 14C-labelled polyunsaturated fatty acids by pike (Esox lucius L.) in vivo

“…In terms of the distribution of lipid within the body, previous studies have established that the pike belongs to the group of fish which have a very lean flesh but contain substantial deposits of lipid in visceral adipose tissue and have a liver with a relatively high lipid content (Schwalme and Mackay 1992;Schwalme et al 1993). As well as confirming this fact, the present study shows that the kidney and heart have a lipid content intermediate between the flesh and the liver and that the lipid content of the pike brain is similar to that reported elsewhere for the rainbow trout and cod (Tocher and Harvie 1988).…”

“…At the same time a detailed analysis of the lipid classes of pike was carried out since, although some information is available for this species in North America (Schwalme et al 1993), very little data has been published on the lipid composition of pike from European waters.…”

Réponses Physiologiques De Sept Espèces De Poissons Lacustres À Un Stress De Capture (Filet Maillant Et Épuisette).

“…L'utilisation de filets maillants, engins de pêche passifs, a été préconisée par l' EIFAC (1975) et citée par BARBIER (1985) pour certaines investigations dans les lacs, réservoirs et milieux potamiques. Ce moyen de capture, ou plus récemment celui des filets maillants verticaux, a montré sa valeur pour les études de recensement (DEGIORGI et ai, 1993 ;FLESCH et al, 1995 ;HANSSON et RUDSTAM, 1995) mais s'est avéré également satisfaisant pour une récupération en lacs et rivières d'un grand nombre de poissons dans un état sanitaire correct pour des recherches sur leurs compositions corporelle et tissulaire (NEWSOME et LEDUC, 1975 ;MEDFORD et MACKAY, 1978 ;CAMINADE, 1986 ;SCHWALME et al, 1993 ;FERRONI, 1996 ;ESCORIHUELA et PARENT, 1997).…”