Utilization of yolk fatty acids by goldfish embryos and larvae

Abstract

In each of two separate experiments, eggs from a single female goldfish were fertilized, incubated at 22~ and sampled regularly up to day 6 when the larvae could be expected to commence feeding. Hatching normally occurred on Day 4. Lipids were extracted from the eggs and larvae and the neutral lipid and neutral phospholipids were isolated on aminopropyl columns. Fatty acid analysis of the eggs revealed the typical situation in fish where the phospholipids were rich in polyunsaturated fatty acids (PUFA) and the neutral lipids were rich in monounsaturated fatty acids (MUFA). Assay of lipid masses revealed that little depletion of lipid occurred until after hatch and that the neutral phospholipids were the principal fraction consumed. Although the neutral lipid mass did not change substantially during development, its fatty acid profile did. The proportions of several PUFA in the neutral lipids, especially 22:6(n-3), 20:5(n-3) and 20:4(n-6), increased substantially during development while proportions of MUFA and 18:2(n-6) declined. This appears to be a mechanism by which the larva can retain essential fatty acid released on hydrolysis of phospholipid while deriving the benefits of catabolism of phospholipid as fuel, namely the provision of phosphate and choline for intermediary metabolism and for the synthesis of macromolecules and neurotransmitter.

Metabolism and Functions of Lipids and Fatty Acids in Teleost Fish

“…Lipids were utilised as an energy source mainly after hatching in goldfish (Wiegand, 1996b), sturgeon (Gershanovich, 1991), red sea bream and winter flounder , whereas in pike (Desvilettes et al, 1997), striped bass (Chu and Ozkizilcik, 1995), Atlantic herring and cod, lipids were utilised during both embryogenesis and early larval development (Tocher et al, 1985a;Fraser et al, 1988). The specific classes utilised again depends largely on the type of eggs, with neutral lipid-rich eggs primarily utilising neutral lipids as in red sea bream, red drum, striped bass (Chu and Ozkizilcik, 1995) and sturgeon (Gershanovich, 1991), whereas phosphoglyceride-rich eggs such as those from herring, cod and African catfish primarily utilised PtdCho Verreth et al, 1994).…”

“…In contrast, in marine pelagic eggs that contain higher lipid levels, reflecting high levels of neutral lipid in oil globules or otherwise, such as from sea bream, sea bass, Senegal sole and dentex, lipids are utilised primarily after hatching and mainly as neutral lipid, whether from the oil globule or otherwise (Ronnestad et al, 1994(Ronnestad et al, , 1998Mourente and Vazquez, 1996;Mourente et al, 1999a). Phosphoglyceride was also the predominant lipid catabolised in goldfish (Wiegand, 1996b) but in pike, PtdCho, triacylglycerol and steryl esters were all catabolised (Desvilettes et al, 1997). In rainbow trout, phosphoglyceride was slowly and continuously metabolised, but triacylglycerol was not utilised until after hatching, whereas in Atlantic salmon, triacylglycerol was catabolised throughout development.…”

“…Similarly, in cod the fatty acids in PtdCho were catabolised non-selectively (Finn et al, 1995). However, in herring and goldfish, much of the PUFA liberated by the catabolism of PtdCho was selectively retained in the neutral lipid pool (Tocher et al, 1985b;Wiegand, 1996b). Although also utilised for energy, PUFA were relatively conserved in comparison with saturated and monounsaturated fatty acids during development of Senegal sole (Mourente and Vazquez, 1996) and in cod, monounsaturated fatty acids in triacylglycerol were selectively catabolised in comparison with PUFA (Finn et al, 1995).…”

Rétention Des Ovules Après Ovulation Dans La Cavité Ovarienne De La Carpe Herbivore : Composition Des Ovules Et Capacité De Développement Des Œufs Et Des Alevins.

“…Chez bon nombre de poissons, ces composés semblent être essentiels pour l'accomplissement de la fécondation et l'initiation de l'embryogenèse (SHIMMA et al, 1978 ;PARRISH et al, 1994 ;WIEGAND, 1996 ;TOCHER et al, 1996 ;NAVAS et al, 1997).…”

“…Une telle tolérance serait en rapport avec leur qualité et leur composition biochimique. La composition biochimique des ovules des poissons étant tributaire des statuts nutritionnel et héréditaire (LAVENS et SORGELOOS, 1991 ;CERDA et al, 1995 ;HARREL et WOODS, 1995 ;FERNANDEZ-PALACIOS et al, 1995 ;VERAKUNPIRIYA et al, 1996 ;BELL et al, 1997) et affectant considérablement la viabilité des oeufs et la survie de la progéniture (BLOM et DABROWSKI, 1995, 1996CERDA et al, 1994CERDA et al, , 1995FERNADEZ-PALACIOS et al, 1995RAINUZZO et al, 1997).…”