title: A deficiency or an excess of dietary threonine level affects weight gain, enzyme activity, immune response and immune-related gene expression in juvenile blunt snout bream (Megalobrama amblycephala).
abstract: A feeding trial was conducted to investigate the impacts of deficient and excess dietary threonine levels on weight gain, plasma enzymes activities, immune responses and expressions of immune-related genes in the intestine of juvenile blunt snout bream. Triplicate groups of fish (initial weight 3.01 ± 0.01 g, 30 fish per tank) were fed with deficient (0.58%), optimum (1.58%) and excess (2.58%) threonine level diets to near satiation four times a day for 9 weeks. A mixture of l-amino acids was supplemented to simulate the whole body amino acid pattern of blunt snout bream, except for threonine. The results showed that both deficiency and excess threonine level diets significantly (P < 0.05) reduced the weight gain of blunt snout bream. Excess dietary threonine level triggered plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities (P < 0.05); whereas superoxide dismutase (SOD) activity was not significantly influenced by imbalanced-dietary threonine level (P > 0.05). Plasma complement component 3 (C3) and component 4 (C4) concentrations were significantly depressed by the deficiency of dietary threonine (P < 0.05). Dietary threonine regulated the target of rapamycin (TOR), eukaryotic translation initiation factor 4E-binding protein 2 (4E-BP2), tumour necrosis factor alpha (TNF-α) and copper-zinc superoxide dismutase (Cu/Zn-SOD) gene expressions in the intestine of blunt snout bream, which may go further to explain the adverse effects of a deficient and/or an excess dietary threonine level on growth, immunity and health of fish. Furthermore, the present study also suggests that an optimum dietary threonine could play an important role in improving growth, enhancing immune function and maintaining health of fish.
authors.affiliation: Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, Jiangsu 214081, PR China. Electronic address: mike2692011@gmail.com.
authors.forename: Habte-Michael
authors.initials: HM
authors.lastname: Habte-Tsion
authors.affiliation: Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, Jiangsu 214081, PR China; Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Shanshui East Road No. 9, Wuxi, Jiangsu 214081, PR China. Electronic address: gexp@ffrc.cn.
authors.forename: Xianping
authors.initials: X
authors.lastname: Ge
authors.affiliation: Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, Jiangsu 214081, PR China; Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Shanshui East Road No. 9, Wuxi, Jiangsu 214081, PR China. Electronic address: liub@ffrc.cn.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.affiliation: Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, Jiangsu 214081, PR China; Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Shanshui East Road No. 9, Wuxi, Jiangsu 214081, PR China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xie
authors.affiliation: Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, Jiangsu 214081, PR China; Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Shanshui East Road No. 9, Wuxi, Jiangsu 214081, PR China.
authors.forename: Mingchun
authors.initials: M
authors.lastname: Ren
authors.affiliation: Wuxi Fisheries College, Nanjing Agricultural University, Wuxi, Jiangsu 214081, PR China; Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Shanshui East Road No. 9, Wuxi, Jiangsu 214081, PR China.
authors.forename: Qunlan
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Shanshui East Road No. 9, Wuxi, Jiangsu 214081, PR China.
authors.forename: Linghong
authors.initials: L
authors.lastname: Miao
authors.affiliation: Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Shanshui East Road No. 9, Wuxi, Jiangsu 214081, PR China.
authors.forename: Liangkun
authors.initials: L
authors.lastname: Pan
authors.affiliation: Key Laboratory for Genetic Breeding of Aquatic Animals and Aquaculture Biology, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Shanshui East Road No. 9, Wuxi, Jiangsu 214081, PR China.
authors.forename: Ruli
authors.initials: R
authors.lastname: Chen
mesh_terms: D000818:Animals; D003530:Cyprinidae / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation / Q000276:immunology*; D007113:Immunity, Innate; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000276:immunology*; D010949:Plasma / Q000201:enzymology; D011897:Random Allocation; D013912:Threonine / Q000172:deficiency / Q000378:metabolism*; D015430:Weight Gain
chemical_list: D029941:Fish Proteins; D013912:Threonine
keywords: Blunt snout bream; Gene expression; Immune response; Threonine-Imbalance; Weight gain