Threonine Affects Intestinal Function, Protein Synthesis and Gene Expression of TOR in Jian Carp (Cyprinus carpio var. Jian)

Abstract

This study aimed to investigate the effects of threonine (Thr) on the digestive and absorptive ability, proliferation and differentiation of enterocytes, and gene expression of juvenile Jian carp (Cyprinus carpio var. Jian). First, seven isonitrogenous diets containing graded levels of Thr (7.4–25.2 g/kg diet) were fed to the fishes for 60 days. Second, enterocyte proliferation and differentiation were assayed by culturing enterocytes with graded levels of Thr (0–275 mg/l) in vitro. Finally, enterocytes were cultured with 0 and 205 mg/l Thr to determine protein synthesis. The percent weight gain (PWG), specific growth rate, feed intake, feed efficiency, protein retention value, activities of trypsin, lipase and amylase, weights and protein contents of hepatopancreas and intestine, folds heights, activities of alkaline phosphatase (AKP), γ- glutamyl transpeptidase and Na+/K+-ATPase in all intestinal segments, glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities in hepatopancreas, and 4E-BP2 gene expression in muscle, hepatopancreas and intestinal segments were significantly enhanced by Thr (p<0.05). However, the plasma ammonia concentration and TOR gene expression decreased (p<0.05). In vitro, Thr supplement significantly increased cell numbers, protein content, the activities of GOT, GPT, AKP and Na+/K+-ATPase, and protein synthesis rate of enterocytes, and decreased LDH activity and ammonia content in cell medium (p<0.05). In conclusion, Thr improved growth, digestive and absorptive capacity, enterocyte proliferation and differentiation, and protein synthesis and regulated TOR and 4E-BP2 gene expression in juvenile Jian carp. The dietary Thr requirement of juvenile Jian carp was 16.25 g/kg diet (51.3 g/kg protein) based on quadratic regression analysis of PWG.

Supplementation of enzyme-treated soy protein saves dietary protein and promotes digestive and absorptive ability referring to TOR signaling in juvenile fish

“…In this study, data firstly showed that optimal ETSP in the low-protein diet downregulated 4E-BP2 mRNA levels in PI, MI, and DI, which showed a contrary tendency to that of TOR. Previous studies from our laboratory showed that intestinal 4E-BP2 gene expression also showed a contrary tendency as that of TOR towards dietary threonine (Feng et al 2013) and isoleucine (Zhao et al 2012). However, the reasons for these changes are unknown, since there is no other information about the effect of ETSP on fish TOR and 4E-BP2 gene expressions.…”

Effects of dietary essential amino acid deficiencies on the growth performance and humoral immune response in silvery-black porgy (Sparidentex hasta) juveniles

“…In the present study, silvery‐black porgy juveniles fed the threonine‐deficient diet (1.12% DM) had the lowest survival rates, which may be attributed to some physiological and metabolic dysfunctions in this experimental group. In this context, it has been reported that threonine is involved in many physiological and biochemical processes, including somatic growth, feed efficiency, digestive and absorptive, gene expression regulation, antioxidant and immune functions in different fish species (Gao Feng et al., ; Habte‐Tsion, Ge, et al., , Habte‐Tsion, Liu, et al., , Habte‐Tsion, Ren, et al., , Habte‐Tsion, Ren, Liu, Xie, et al., , Habte‐Tsion et al., ). Moreover, along with arginine‐ (1.73% DM) and lysine (1.29% DM)‐deficient diets, all immunological parameters were lower in fish fed the threonine‐deficient diet than in the other groups, which indicated its significant role in fish health.…”

Dietary leucine improves flesh quality and alters mRNA expressions of Nrf2-mediated antioxidant enzymes in the muscle of grass carp ( Ctenopharyngodon idella )

“…In spite of this, information regarding the effect of leucine on TOR and S6K1 is limited in fish. Studies from our laboratory showed that arginine (Wang et al, 2015) and threonine (Feng et al, 2013a) regulated the gene transcription of TOR in the muscle of Jian carp. These data show that there may be a close relationship between leucine and TOR/S6K1 in fish muscle, which warrants investigation.…”