优质肉鸡不同胫色皮肤组织形态学及黑色素生成相关基因的表达分析

Characteristic Histomorphology of Different Tibial Skin and Expression of Genes Related to Melanogenesis in Broiler

为阐明优质肉鸡胫皮肤发育的组织形态学特点,以及黑色素高度沉积的分子机制,选取2～10周龄S3系(黑色胫)和L系(黄色胫)肉鸡胫皮肤组织,进行组织形态学分析,并检测不同胫色的胫皮肤组织中Pax3、Mitf与Tyr基因的表达。结果显示:在优质肉鸡快速生长阶段,两品系间胫皮肤黑色素沉积差异明显,S3系胫皮肤黑色素数量呈波动性变化,2～6周龄时逐渐增加,而后逐渐减少,但同周龄之间S3系胫皮肤黑色素的数量极显著大于L系(P<0.01)。不同胫色鸡胫皮肤黑色素面积均随周龄的增加而增加,但L系胫皮肤黑色素随面积极显著小于S3系(P<0.01)。Pax3与Tyr在S3系胫皮肤中表达量显著高于L系(P<0.001),而Mitf则无明显差异(P>0.05)。结果表明:在胫皮肤发育分化过程中,S3系与L系胫皮肤黑色素细胞的迁移、黑色素细胞的分裂成熟、黑色素小体的形成、黑色素颗粒的转运路线可能存在差异;胫皮肤黑色素高度沉积与Pax3、Tyr的表达有关,Pax3下调可以促进Tyr的表达,进而使黑色素细胞黑色素的生成增加。

The objective of this study is to elucidate the characteristics in histomorpholog and the potential molecular mechanisms underlying melanin deposition of tibial skin in high quality broiler. Tibial skin between L line(yellow tibia)and S3 line(dark tibia) during 2, 4, 6, 8, 10 weeks were analyzed by the characteristics of histomorphology. The mRNA expression of Pax3, Mitf and Tyr in skin of two lines were examined using QRT-PCR method at the same time.The results show that the differences of melanin deposition in tibial skin between the two lines are obvious. The tibial skin melanin increased gradually during 2 to 6 weeks of age, then gradually decreased in S3 line. Tibial skin melanin of S3 was significantly greater than that of L line at the same week age(P<0.01). The area of melanin in different tibial skin was increased with the increase of age, but L line was significantly less than S3 line(P<0.01). The tibial skin mRNA levels of Pax3 and Tyr were significantly higher in S3 line than those in L line(P<0.001), whereas no difference was observed in Mitf expression in skins between tibial skin of two line(P>0.05). The migration routes of tibial skin melanocytes between S3 and L line might be diverse in the process of tibial skin differentiation. It was speculated that the expression of Pax3 and Tyr had certain correlation with the melanin deposition. Down regulation of Pax3 might promote the Tyr expression, then increased the melanin production of melanocytes.