Is it possible to influence European sea bass (Dicentrarchus labrax) juvenile metabolism by a nutritional conditioning during larval stage?

Abstract

The purpose of this study was to check if it is possible to influence sea bass juvenile metabolism by a conditioning of larvae from day 6 post hatching to day 45 to a low or a high HUFA compound diet (LH, 0.8% EPA + DHA and HH, 2.2% EPA + DHA) when reared at 16 or 22 °C. Following a 3-month intermediate period (at 19 °C using a commercial diet), the adaptability of the 4 initial larval groups to a HUFA experimental deprived diet (0.5% EPA + DHA) were tested at 19 °C in a 60 day-experiment (d-151-211). The four experimental duplicated conditions were ex-LH16 and ex-HH16 for the 2 groups previously reared at 16 °C (initial weight, 7.3 ± 0.5 g) and ex-LH22 and ex-HH22 for the 2 groups previously reared at 22 °C (initial weight, 11.1 ± 0.5 g). Survival was maximal and there was a 1.6-2 fold increase in mass during the experiment. Growth was similar in the 4 experimental groups: NS difference in growth curve slopes (P = 0.7). At the end of the experiment (d-211), whole body fat levels were in the same range in all groups (13-15% WW). The fatty acid (FA) composition in polar lipids (PL) and total lipids (TL) were significantly affected by initial weight related to larvae conditioning, which can be mainly attributed to a dilution effect (impact of initial FA content on final FA content versus relative mass increase during the course of the experiment). Conversely to this trend, DHA content in PL was higher in the ex-LH groups than in the ex-HH groups whatever thermal conditioning of larvae was. This indicated that ex-LH groups had a better capacity to adapt to a deficient HUFA diet than ex-HH fish. The relative expression of the delta-6 desaturase (Δ6D) was significantly higher in ex-LH than in ex-HH groups (P < 0.001) between d-151 and d-181, which suggested that Δ6D transcription in ex-LH groups was positively modulated by the HUFA-deprived diet. This stimulation of the first step of the desaturation/elongation pathway could allow synthesizing FA needed to compensate low dietary HUFA supply. This study shows for the first time that it seems possible to influence juvenile fish metabolism by a nutritional conditioning during the larval stage.

An early-life hypoxia event has a long-term impact on protein digestion and growth in European sea bass juvenile

“…Recent studies suggest that besides the initiation of a gene transcription programme via hypoxia-inducible factor (HIF), hypoxia can also modulate histone methylation via an epigenetic mechanism (Yang et al, 2009). Metabolic programming of digestive enzymes by carbohydrate or lipid conditioning has already been demonstrated in fish (Geurden et al, 2007;Vagner et al, 2007); however, the present study suggests for the first time that such nutritional programming could also occur for proteins, even though this effect was indirectly due to a hypoxia-induced diet restriction. Interestingly, similar longterm consequences have been reported in a higher vertebrate: differences in intestinal enzyme activities were induced by a nutritional protein deficit during the weaning period of rat pups (Egorova et al, 2008;Timofeeva et al, 2009).…”

Glucose overload in yolk has little effects on the long term modulation of carbohydrate metabolic genes in zebrafish (Danio rerio)

“…The opportunities to exert a nutritional stimulus during a stage of high metabolic plasticity, such as fish embryogenesis or early larval development, are limited to, e.g. maternal nutrient transfer (Fernández-Palacios et al, 1997;Fernández-Palacios et al, 1995) and the onset of exogenous feeding (Geurden et al, 2007;Vagner et al, 2007). A previous study by Geurden et al showed that a short hyperglucidic stimulus exerted at the onset of feeding, upregulated carbohydrate digestive enzymes in rainbow trout at a later juvenile stage, suggesting some long-term physiological changes (Geurden et al, 2007).…”

Appetite and Feed Intake

“…A short exposure to specific nutrients early in life would therefore seem to influence later processing of these nutrients (Geurden et al 2007). Similarly, European seabass exposed to a diet low in highly unsaturated fatty acids (HUFAs) as larvae are better able to adapt to a diet low in HUFAs than are conspecifics fed a high HUFA diet when young (Vagner et al 2007).…”