低蛋白饲料补充必需氨基酸对异育银鲫生长、氨基酸转运和mTOR信号通路相关基因的影响

LOW-PROTEIN DIETS SUPPLEMENTED WITH ESSENTIAL AMINO ACIDS ON GROWTH,AMINO ACID TRANSPORTERS AND GENE EXPRESSION OF THE MTOR SIGNALING PATHWAY IN GIBEL CARP(CARASSIUS GIBELIO)

实验以初重为(12.71±0.11)g的异育银鲫“中科5号”(Carassius gibelio var.CAS V)为研究对象,基于异育银鲫必需氨基酸需求量,探究在低蛋白饲料中补充必需氨基酸对异育银鲫生长、消化、氨基酸转运和mTOR信号通路相关基因表达的影响。实验设计3组等能饲料:CON组(35%粗蛋白)、LP组(28%粗蛋白)和LP+EAA组(28%粗蛋白+晶体氨基酸),养殖周期为50d。实验结果显示:低蛋白饲料中补充必需氨基酸显著提高异育银鲫生长性能(P<0.05),并与CON组无显著差异(P>0.05);LP+EAA组的肝脏谷草转氨酶活性显著高于LP组(P<0.05),而谷丙转氨酶活性各组间无显著差异(P>0.05);补充必需氨基酸对肠道中胰蛋白酶和淀粉酶活性有显著影响(P<0.05),而对糜蛋白酶和脂肪酶无显著影响(P>0.05)。肠道中cat2、asct2和b0at1三种氨基酸转运蛋白显著上调(P<0.05),LP组的b0,+at的相对表达量显著下调(P<0.05),而pept1的表达各组间无显著差异(P>0.05);肝脏中LP组tor相对表达量显著降低(P<0.05),LP+EAA组的s6k1表达水平显著上调(P<0.05),而4ebp2和eif4e的相对表达量在各组间无显著差异(P>0.05);背肌中LP+EAA组的tor表达水平显著上调(P<0.05),LP组的eif4e表达水平显著下调(P<0.05),而s6k1和4ebp2的相对表达量在各组间无显著差异(P>0.05)。综上所述,向异育银鲫“中科5号”幼鱼饲料中补充必需氨基酸至需求量可以将饲料蛋白水平由35%降至28%,而不会对生长、氨基酸转运和mTOR信号通路相关基因表达等产生负面影响。

In this experiment,gibel carp(Carassius gibelio var.CASⅤ)with initial weight of(12.71±0.11)g was selected as the research object.Based on the essential amino acids requirements of gibel carp,we investigated the effects of supplemented with essential amino acids in low protein diet on the growth,digestion and protein synthesis of gibel carp.Three isoenergetic diets were designed:CON group(35%crude protein),LP group(28%crude protein)and LP+EAA group(28%crude protein+crystalline amino acids).The results showed that supplementing the low protein diet with essential amino acids significantly improved the growth performance of gibel carp(P<0.05),and there was no significant difference compared with the CON group(P>0.05).The activity of aspartate transaminase(AST)in liver of LP+EAA group was significantly higher than that of LP group(P<0.05),but there was no significant difference in alanine transaminase(ALT)activity among all groups(P>0.05).Supplementation with essential amino acids had significant effects on the activities of trypsin and amylase in the intestinal(P<0.05),but had no significant effects on chymotrypsin and lipase(P>0.05).The relative expression levels of three amino acids transporters cat2,asct2 and b0at1 in intestinal were significantly up-regulated(P<0.05),while the relative expressions of b0,+at in LP group were significantly down-regulated(P<0.05),and there was no significant difference in the relative expression of pept1 among all groups(P>0.05).The relative expression level of tor in liver of LP group was significantly decreased(P<0.05),while the relative expression level of s6k1 in LP+EAA group was significantly up-regulated(P<0.05),however,the relative expression levels of 4ebp2 and eif4e showed no significant difference among all groups(P>0.05).In dorsal muscle,the relative expression of tor in LP+EAA group was significantly up-regulated(P<0.05),and eif4e expression in LP group was significantly down-regulated(P<0.05),but there were no significant differences in the relative expression levels of s6k1 and 4ebp2 among all groups(P>0.05).In conclusion,reducing the diet protein level from 35%to 28%of juvenile gibel carp(Carassius gibelio var.CASⅤ)is possible without negative effects on growth,through supplemented with essential amino acids.