基于组织形态学和基因表达差异探究影响雪峰乌骨鸡胸肌黑色素沉积的因素

Factors Affecting Melanin Deposition in Breast Muscle of Xuefeng Black-bone Chicken Based on Differences of Histomorphology and Gene Expression

为探究乌骨鸡胸肌乌色差异的原因,研究选取24日龄胸肌高乌(高乌组)和低乌(低乌组)的雪峰乌骨鸡各3只,对其胸肌中的黑素小体面积、比例和数量密度进行组间比较,同时检测胸肌中DCT、GPNMB、TYR、TYRP1、MLANA、PMEL、TUBB3和EDNRB2等8个黑色素沉积相关基因的mRNA相对表达水平,并分析其与胸肌L值及黑素小体面积、比例和数量密度的相关性。结果显示:①胸肌中的黑色素细胞以不规则形态分布于肌束膜中,并且黑色素细胞的分布在高乌组中更密集;黑素小体近似椭圆形,并且具备各时期的典型特征,此外在两组中均发现黑素小体的降解现象;黑色素细胞内部的黑素小体排布紧密,而外部的黑素小体主要以成团的方式存在于肌内膜和肌束膜中;②高乌组中的总黑素小体面积以及成熟黑素小体面积和比例显著大于低乌组(P<0.05),而未成熟黑素小体面积和数量密度显著小于低乌组(P<0.05);同组中的成熟黑素小体面积显著大于未成熟黑素小体面积(P<0.05);③DCT、GPNMB、TYR、TYRP1、MLANA、PMEL、TUBB3和EDNRB2在高乌组中的mRNA表达水平显著高于低乌组(P<0.05);④DCT、GPNMB、TYR、TYRP1、MLANA、PMEL、TUBB3和EDNRB2的mRNA相对表达水平与胸肌L值以及未成熟黑素小体面积和数量密度存在显著负相关(P<0.05),与总黑素小体面积以及成熟黑素小体面积和比例存在显著正相关(P<0.05);DCT、TYRP1和MLANA的mRNA相对表达水平与成熟黑素小体数量密度存在显著正相关(P<0.05)。以上结果提示黑色素沉积相关基因的调控作用所导致的黑色素细胞和黑素小体的差异是造成雪峰乌骨鸡胸肌不同乌色的重要原因。

In order to investigate the causes leading to variation in blackness of breast muscle,three individuals of highblackness pectoral muscle(HB)and three individuals of low-blackness pectoral muscle(LB)were selected in this study.The ar⁃ea,proportion and quantitative density of melanosomes in breast muscle were compared between the two groups.The mRNA rela⁃tive expression levels of eight genes involving in melanin deposition,including DCT,GPNMB,TYR,TYRP1,MLANA,PMEL,TUBB3 and EDNRB2 were detected,and the correlation to L-value of breast muscle,the area,proportion and quantitative density of melanosomes in breast muscle were analyzed.The results showed that:①The melanocytes in breast muscle were irregular in shape and distributed in the perimysium,and the number of melanocytes of HB was higher than that of LB.The melanosomes in the pectoral muscle were approximately elliptic in shape and had typical characteristics of each period,and the degradation of me⁃lanosomes was found in both groups.The melanosomes inside the melanocytes were closely arranged,while the melanosomes out⁃side the melanocytes mainly existed in the endomysium and perimysium in the form of clusters.②The area of total melanosomes,the area and proportion of mature melanosomes in HB were significantly larger than those in LB(P<0.05),while the area and num⁃ber density of immature melanosomes in HB were significantly smaller than those in LB(P<0.05).The area of mature melano⁃somes in the same group was significantly larger than that of immature melanosomes(P<0.05).③The mRNA expression levels of DCT,GPNMB,TYR,TYRP1,MLANA,PMEL,TUBB3 and EDNRB2 in HB were significantly higher than those in LB(P<0.05).④The mRNA relative expression levels of DCT,GPNMB,TYR,TYRP1,MLANA,PMEL,TUBB3 and EDNRB2 were significantly negatively correlated with L-value of breast muscle,the area and number density of immature melanosomes(P<0.05),and signifi⁃cantly positively correlated with the area of total melanosomes,the area and proportion of mature melanosomes(P<0.05).The mRNA relative expression levels of DCT,TYRP1 and MLANA were significantly positively correlated with the number density of mature melanosomes(P<0.05).The above results suggested that the difference of melanocytes and melanosomes caused by the regulation of genes related to melanin deposition was an important reason for breast muscle of different blackness in Xuefeng black-bone chicken.