Effects of the total replacement of fish-based diet with plant-based diet on the hepatic transcriptome of two European sea bass (Dicentrarchus labrax) half-sibfamilies showing different growth rates with the plant-based diet

Abstract

BackgroundEfforts towards utilisation of diets without fish meal (FM) or fish oil (FO) in finfish aquaculture have been being made for more than two decades. Metabolic responses to substitution of fishery products have been shown to impact growth performance and immune system of fish as well as their subsequent nutritional value, particularly in marine fish species, which exhibit low capacity for biosynthesis of long-chain poly-unsaturated fatty acids (LC-PUFA). The main objective of the present study was to analyse the effects of a plant-based diet on the hepatic transcriptome of European sea bass (Dicentrarchus labrax).ResultsWe report the first results obtained using a transcriptomic approach on the liver of two half-sibfamilies of the European sea bass that exhibit similar growth rates when fed a fish-based diet (FD), but significantly different growth rates when fed an all-plant diet (VD). Overall gene expression was analysed using oligo DNA microarrays (GPL9663). Statistical analysis identified 582 unique annotated genes differentially expressed between groups of fish fed the two diets, 199 genes regulated by genetic factors, and 72 genes that exhibited diet-family interactions. The expression of several genes involved in the LC-PUFA and cholesterol biosynthetic pathways was found to be up-regulated in fish fed VD, suggesting a stimulation of the lipogenic pathways. No significant diet-family interaction for the regulation of LC-PUFA biosynthesis pathways could be detected by microarray analysis. This result was in agreement with LC-PUFA profiles, which were found to be similar in the flesh of the two half-sibfamilies. In addition, the combination of our transcriptomic data with an analysis of plasmatic immune parameters revealed a stimulation of complement activity associated with an immunodeficiency in the fish fed VD, and different inflammatory status between the two half-sibfamilies. Biological processes related to protein catabolism, amino acid transaminations, RNA splicing and blood coagulation were also found to be regulated by diet, while the expression of genes involved in protein and ATP synthesis differed between the half-sibfamilies.ConclusionsOverall, the combined gene expression, compositional and biochemical studies demonstrated a large panel of metabolic and physiological effects induced by total substitution of both FM and FO in the diets of European sea bass and revealed physiological characteristics associated with the two half-sibfamilies.

Replacement of Marine Fish Oil with de novo Omega‐3 Oils from Transgenic Camelina sativa in Feeds for Gilthead Sea Bream (Sparus aurata L.)

“…Up-regulation in srebp1 expression in liver was observed in fish fed the three VO in agreement with studies carried out in elovl5 −/− mice that indicated low levels of EPA and DHA lead to activation of this transcription factor [55]. Similar results have been obtained in other fish species when fed low levels of n-3 LC-PUFA or VO [50, 56–58]. Up-regulation of srebp1 in VO-fed fish could lead to the regulation of srebp1 target genes such as fads2 , hl , lpl , cpt1a and cpt1b .…”

Effects of dietary concentrated mannan oligosaccharides supplementation on growth, gut mucosal immune system and liver lipid metabolism of European sea bass (Dicentrarchus labrax) juveniles

“…Indeed, a higher tissue percentage of this LC-PUFA could be related with the down-regulation of delta 6/5 desaturase gene (FADS2) found as a consequence of a feed back negative mechanism. However, implication of other mechanisms or even a post-transcriptional regulation of its expression as it occurs in European sea bass fed vegetable diets [49], should not be discarded.…”

“…For liver, 5 genes involved in lipid metabolic pathways (FADS2, LPL, FABP7, ANGPTL3, HMGRC) were analyzed by real-time PCR following the conditions described before by Ref. [49], using elongation factor-1 (ef-1) as housekeeping. Specific primers used and annealing temperatures for each gene assayed are indicated in Table 4.…”

The evolution of viviparity: molecular and genomic data from squamate reptiles advance understanding of live birth in amniotes

“…Gene functions may also be inferred using diet manipulations and subsequent effects on nutrient transporter and packaging genes (e.g. Geay et al (2011) and Hamill et al (2013)). …”