饲料不同锌源对草鱼幼鱼肌肉锌转运和发育的影响

DIFFERENT DIETARY ZINC SOURCES ON MUSCLE ZINC TRANSPORT ANDDEVELOPMENT OF JUVENILE GRASS CARP(CTENOPHARYNGODON IDELLA)

为了探究饲料中添加不同锌源对草鱼幼鱼肌肉发育的影响,实验以草鱼(Ctenopharyngodon idella)幼鱼为研究对象,共设置5组饲料,分别为对照组(Control,不添加任何锌源)、硫酸锌组(ZnSO_(4))、纳米氧化锌组(ZnO NPs)、乳酸锌组(Zn-Lac)和甘氨酸锌组(Zn-Gly),养殖实验共持续8周。结果表明,饲喂4种锌源饲料的草鱼肌肉肌纤维直径相较于对照组增加,其中以甘氨酸锌组草鱼肌肉直径>50μm的肌纤维频率最高。锌转运相关基因测定结果显示,硫酸锌组、纳米氧化锌组、乳酸锌组和甘氨酸锌组相较于对照组显著影响了部分锌转运相关基因mRNA的表达(P<0.05),同时硫酸锌相较于其他锌源对于锌转运相关基因表达的调控有更显著的影响(P<0.05);与对照组相比,硫酸锌组、纳米氧化锌组、乳酸锌组和甘氨酸锌组mef2d、myod和myog的mRNA表达量显著增加(P<0.05),在不同锌源组之间比较时,甘氨酸锌组myod的mRNA表达量显著高于其他组。根据MAPK/JNK信号通路关键因子基因测定结果,硫酸锌组、纳米氧化锌组、乳酸锌组和甘氨酸锌组会显著增加map2k7、map3k2和jnk基因mRNA的表达(P<0.05),其中,甘氨酸锌组map2k7基因mRNA表达显著高于其他锌源组。研究表明,以甘氨酸锌作为锌源添加到饲料中更有利于草鱼的肌肉发育,MAPK/JNK信号通路可能介导这一重要的生物学过程。研究为深入探讨甘氨酸锌对鱼类肌肉发育的作用提供了理论依据,为甘氨酸锌在鱼类饲料中的应用奠定基础。

In this study,juvenile grass carp(Ctenopharyngodon idella)was utilized as the object to explore the effect of different dietary zinc sources on muscle zinc transport and development.Five experimental diets were formulated,including a reference diet without any added zinc sources(Control),a diet supplemented with Zn sulfate(ZnSO_(4)),Zn dioxide nanoparticles(ZnO NPs),Zn lactate(Zn-Lac),and Zn glycine chelate(Zn-Gly),respectively.Grass carp with an initial body weight of 3.54 g/fish were fed one of these five experimental diets for 8 weeks.The myofiber diameters of grass carp fed diets containing the four zinc sources showed increases compared to those in reference diet group,with the Zn-Gly group exhibiting the highest frequency of myofibers with diameter>50μm.The mRNA expression levels of Zn transport-related genes significantly changed in all experimental groups(ZnSO_(4),ZnO NPs,Zn-Lac,and Zn-Gly),compared to the reference diet group,particularly in the Zn sulfate group(P<0.05).Furthermore,the addition of the four zinc sources up-regulated the mRNA abundance of muscle development-relevant genes(mef2d,myog,and myod)compared to the reference diet group(P<0.05).Notably,the myod mRNA level was significantly higher in the Zn-Gly group than those in the other three dietary groups(ZnSO_(4),ZnO NPs,and Zn-Lac)(P<0.05).Moreover,the mRNA expression levels of map3k2,map2k7,and jnk genes were significantly higher in grass carp fed with ZnSO_(4),ZnO NPs,Zn-Lac,and Zn-Gly groups than those in the reference diet group(P<0.05).Importantly,the mRNA expression level of map2k7 was significantly up-regulated in the Zn-Gly group than those in the ZnSO_(4),ZnO NPs,and Zn-Lac groups(P<0.05).This study suggests that Zn-Gly is beneficial for muscle development and that the MAPK/JNK signaling pathway potentially mediates this crucial biological process.The present study provide the good basis for further understanding into the effect of Zn-Gly on muscle development in fish and offer implications for its application in the aquafeeds.