Effects of partial dietary supplementation of fish meal with soymeal on the stress and apoptosis response in the digestive system of common dentex (Dentex dentex)

Efthimia Antonopoulou,Stavros Chatzifotis,Konstantinos Feidantsis,Eleni Chouri,Antigone Lazou

doi:10.1186/s40709-017-0071-1

Abstract

BackgroundSoybean is a common alternative protein source of plant origin in aquafeeds as it has a reasonably balanced amino acid profile and is widely available. This study aimed to investigate the influence of partial substitution of fish meal with soy meal on cytoprotective pathways and apoptosis in the digestive system of common dentex (Dentex dentex), using the activation of Hsp70, p38 MAPK, Bcl-2 and caspase-3. The experimental approach involved feeding of common dentex with three isoprotein and isoenergetic diets that contained fish meal as a protein source (FM), partial replacement of fish meal by soy meal 25% (SM25) and 40% (SM40) for 3 months.ResultsThe SM40 diet induced Hsp70 activation only in the middle part of intestine. On the other hand, both SM25 and SM40 diets diminished the phosphorylation of p38 MAPK in the anterior and the middle part of intestine, whereas only SM25 induced p38 MAPK phosphorylation in the stomach. Moreover, a decrease in the levels of caspase-3 activity was observed in the middle and posterior intestine, as well as in the stomach after feeding with SM25 diets. Furthermore, Bcl-2 levels were increased by SM40 in the anterior and by SM25 in the middle part of intestine.ConclusionsSM25 and SM40 diets elicited a tissue and soy concentration specific cellular and cell protective response in the different parts of the digestive tract in common dentex.

Highlights

Soybean is a common alternative protein source of plant origin in aquafeeds as it has a reasonably balanced amino acid profile and is widely available
SM40 diet resulted in elevated Hsp70 in the middle part of the intestine in common dentex compared to the control fish meal (FM) group (p < 0.05)
No changes (p > 0.05) were observed in the other examined tissues, including the stomach, the anterior and posterior intestine of fish fed with the soy meal 25% (SM25) and SM40 compared to the FM diet (Fig. 1)

Summary

Introduction

Soybean is a common alternative protein source of plant origin in aquafeeds as it has a reasonably balanced amino acid profile and is widely available. The experimental approach involved feeding of common dentex with three isoprotein and isoenergetic diets that contained fish meal as a protein source (FM), partial replacement of fish meal by soy meal 25% (SM25) and 40% (SM40) for 3 months. Soybean is considered the most interesting substitute of fish meal [5] due to its availability in global markets [6] and its’ reasonably balanced amino acid profile [2]. In common dentex (Dentex dentex), partial substitution of fish meal is possible with 25% of soy protein concentrate without affecting growth, which can be improved further by dietary taurine supplementation of 2 g kg−1 diet [7]. In marine organisms including fish, a common metric to assess the cellular response to stress is the evaluation of certain bio-indicators such as the expression of several proteins (e.g. heat shock proteins-Hsps), the enzymatic activity levels, or DNA and protein damage [12,13,14,15]

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