摘要
本研究旨在探讨饲料蛋白质水平对三倍体虹鳟肌肉组织特性、蛋白质周转和肌肉生长相关基因表达的影响。配制3种等脂等能饲料,蛋白质水平分别为35.4%(低蛋白质组)、45.8%(中蛋白质组)和52.4%(高蛋白质组)。将1 200尾初始体重为(232.8±0.1) g的三倍体虹鳟随机分为3组,每组4个重复,每个重复放养100尾鱼,进行80 d的养殖试验。结果表明:1)低蛋白质组的肌纤维密度和肌纤维数显著高于中、高蛋白质组(P<0.05);各组间肌纤维直径(D)≤20μm的肌纤维比例无显著差异(P>0.05);120μm160μm的肌纤维比例在低蛋白质组最低,显著低于其他2组(P<0.05)。2)随着饲料蛋白质水平的升高,生长激素受体(GHR)、胰岛素样生长因子Ⅰ(IGFⅠ)和胰岛素样生长因子受体Ⅰ(IGFRⅠ)基因相对表达量呈现先上升后下降的趋势,组间差异显著(P<0.05),在中蛋白质组达到最大值;肌分化因子(Myod)、生肌因子5(Myf5)、肌原调节因子4(Mrf4)和肌细胞生成素(Myog)基因相对表达量显著增加(P<0.05)。3)蛋白质合成途径中,中、高蛋白质组蛋白激酶B(AKT)磷酸化与非磷酸化蛋白比值(p-AKT/AKT)显著高于低蛋白质组(P<0.05)。随着饲料蛋白质水平的升高,雷帕霉素靶蛋白(TOR)和真核翻译起始因子4E结合蛋白1(4Ebp1)磷酸化与非磷酸化蛋白比值(pTOR/TOR、p-4Ebp1/4Ebp1)呈现先上升后下降的趋势,各组间差异显著(P<0.05),在中蛋白质组达到最大值;对蛋白质降解途径而言,自噬相关蛋白12l(Atg12l)基因相对表达量随着饲料蛋白质水平的升高逐渐增加(P<0.05)。钙依赖性蛋白酶2(Capn2)基因相对表达量在高蛋白质组显著高于其他2组(P<0.05),同时钙蛋白酶抑制蛋白短亚型(Cast-s)和钙蛋白酶抑制蛋白长亚型(Cast-l)基因相对表达量呈现先上升后下降的趋势,组间差异显著(P<0.05),其中在中蛋白质组达到最大值。肌肉萎缩F-box蛋白25(Fbx25)基因相对表达量呈现先下降后上升的趋势,其中中蛋白质组显著低于低蛋白质组(P <0.05)。综上所述,当饲料蛋白质水平增加到45.8%时,能促进肌纤维的增大,但对肌纤维增生无显著影响;饲料蛋白质水平通过调控肌源性调节因子和生长激素-胰岛素样生长因子通路进而调控肌纤维增大;当饲料蛋白质水平增加到45.8%时,可促进肌肉蛋白质合成代谢;肌肉蛋白质各分解途径在不同饲料蛋白质水平组存在差异。
The study was aimed to explore the effects of dietary protein levels on muscle tissue characteristics,protein turnover and muscle growth-related genes expressions in triploid rainbow trout. Three isolipid and isoenergetic diets were formulated to contain 35.4%(low protein group),45.8%(medium protein group)and 52.4%(high protein group)protein levels. A total of 1 200 triploid rainbow trout with an initial body weight of(232.8±0.1)g were randomly divided into 3 groups with 4 replicates per group and 100 fish per replicate. The experiment lasted for 80 days. The results showed as follows:1)compared to the medium and high-protein groups,the muscle fiber density and number were significantly increased in the low protein group(P<0.05). No difference was observed in the proportion of muscle fibers with a muscle fiber diameter(D)≤20μm among all groups(P>0.05). The proportion of muscle fibers with 120μm 160μm was the lowest in the low protein group(P<0.05). 2)With the increase of dietary protein levels,the growth hormone receptor(GHR),insulin-like growth factorⅠ (IGFⅠ)and insulin-like growth factor receptorⅠ (IGFRⅠ)gene relative expression levels increased and decreased thereafter,there were significantly different among groups(P<0.05),and reached the maximum in medium protein group. The myogenic differentiation antigen(Myod),myogenic regulatory factor 4(Mrf4),myodifferentiation factor 5(Myf5)and myogenin(Myog)gene relative expression levels of muscle increased with the increase of dietary protein levels(P<0.05). 3)In the protein synthesis pathway,the ratio of phosphorylated to total protein(p-AKT/AKT)of protein kinase B(AKT)in medium and high protein groups was significantly higher than that in low protein group(P<0.05). With the dietary protein levels increasing,the ratio of phosphorylated to total protein(p-TOR/TOR and p-4Ebp1/4Ebp1)of target rapamycin(TOR)and eukaryotic translation initiation factor 4E-binding protein 1(4Ebp1)increased firstly and then decreased,there were significantly difference among groups(P<0.05),and reached the maximum in medium protein group. For the protein degradation pathway,with the dietary protein levels increasing,the autophagy related protein 12l(Atg12l)gene relative expression levels of muscle increased with the increase of dietary protein levels(P<0.05). The calpains 2(Capn2)gene relative expression level in the high protein group was significantly higher than that in the low and medium protein groups(P<0.05);at the same time,the short isoforms of calpastatin(Cast-s)and long isoforms of calpastatin(Cast-l)gene relative expression levels of muscle increased then decreased thereafter with the increase of dietary protein levels(P<0.05). The muscle atrophy F-box protein 25(Fbx25)gene relative expression level was firstly decreased and then increased,and medium protein group was significantly lower than low protein group(P<0.05). In summary,when the dietary protein level increase to 45.8%,it can promote the increase of muscle fiber,but has no effect on the proliferation of muscle fiber. Dietary protein level regulates muscle fiber enlargement by regulating myogenic regulatory factor and growth hormone-insulin-like growth factor pathways. When dietary protein level increases to 45.8%,muscle protein metabolism can be promoted. The decomposing pathways of muscle protein are different in different dietary protein level groups.[Chinese Journal of Animal Nutrition,2022,34(5):3194-3207]
作者
李小花
田海宁
李长忠
马睿
孟玉琼
LI Xiaohua;TIAN Haining;LI Changzhong;MA Rui;MENG Yuqiong(Provincial and Ministry Jointly Build the State Key Laboratory of Sanjiangyuan Ecology and Plateau Agriculture,Qinghai University,Xining 810016,China;College of Ecological Environmental Engineering,Qinghai University,Xining 810016,China)
出处
《动物营养学报》
CAS
CSCD
北大核心
2022年第5期3194-3207,共14页
CHINESE JOURNAL OF ANIMAL NUTRITION
基金
国家自然科学基金(31560722)
青海省科技项目(2019-NK-104)。
关键词
蛋白质
三倍体虹鳟
肌肉组织特性
蛋白质周转
肌肉生长
protein
triploid rainbow trout
muscle tissue characteristics
protein turnover
muscle growth
