酪氨酸对固原乌鸡黑色素分布沉积及相关基因表达的影响

Effects of content of tyrosine in diet on distribution and deposition of melanin and expression of melanin-related gene in Guyuan silky fowls

为探究固原乌鸡黑色素分布沉积特征以及在不同日粮酪氨酸水平下黑色素相关基因表达量的变化,明确酪氨酸对固原乌鸡黑色素形成的影响,选取4周龄、体质量差异不显著的健康固原乌鸡150只,随机分为5组,每组3个重复,每个重复10只。日粮酪氨酸添加水平分别为0、0.2%、0.4%、0.6%、0.8%,饲养至12周龄末,利用电镜技术观察不同组织中黑色素的分布特征,利用免疫组织化学和荧光定量PCR方法检测不同组织中黑色素相关基因表达量的变化。试验结果显示:固原乌鸡皮肤、气管与小肠中存在黑色素细胞且大都已分化成熟。TYR在肺脏组织有阳性反应,TYRP1在肌肉与肝脏组织有阳性反应,MITF、CREB1在肺脏、肝脏、小肠、胸肌组织中均有阳性结果。在不同日粮酪氨酸水平下,MITF、TYR、TYRP1基因的表达量与黑色素含量成一定的线性相关。结果表明,固原乌鸡组织黑色素沉积特征与组织中黑色素颗粒合成量相关,而黑色素合成过程中TYR、MITF可能是其主要关键调控基因,日粮中添加酪氨酸能够促进其表达。

The effects of tyrosine on the formation of melanin in Guyuan silky fowls were studied to investigate the characteristics of the distribution and deposition of melanin in Guyuan silky fowls,and the changes in the expression of melanin-related gene under different content of tyrosine in diet.150 healthy Guyuan silky fowls at 4 weeks of age with no significant difference in body weight were randomly divided into 5 groups,with 3 replicates in each group and 10 chickens in each replicate.The content of tyrosine added in diet was 0,0.2%,0.4%,0.6%,and 0.8%,respectively,and the fowls were fed until the end of 12 weeks of age.The electron microscopy was used to observe the characteristics of the distribution of melanin in different tissues of Guyuan silky fowls.The immunohistochemistry and fluorescence quantitative PCR method were used to detect changes in the expression of melanin-related genes in different tissues of Guyuan silky fowls.The results showed that there were melanocytes in the skin,trachea,and small intes⁃tine of Guyuan silky fowls,and most of them were differentiated and matured.TYR had a positive reaction in lung tissue,TYRP1 had a positive reaction in muscle and liver tissue,and MITF and CREB1 had posi⁃tive results in lung,liver,small intestine,and breast muscle tissue.The expression level of MITF,TYR,and TYRP1 gene was linearly correlated with the content of melanin under different content of tyrosine in diet.It is indicated that the characteristics of melanin deposition in tissues of Guyuan silky fowls are related to the amount of melanin granules synthesized in the tissues,and TYR and MITF may be the main key regulatory genes during the synthesis of melanin.Adding tyrosine to the diet can promote the expression of melanin-related genes.