【作者】 韩建； 陈仕玺； 洪万树；

【Author】 Jian Han;Shi Xi Chen;Wan Shu Hong;College of Ocean and Earth Sciences, Xiaman University;

【机构】 厦门大学海洋与地球学院；

【摘要】 大黄鱼是我国一种重要的海水经济鱼类,肤色金黄,是其重要的经济性状。然而,经过长期驯养,养殖大黄鱼容易出现肤色白化现象,只有在夜晚才呈现金黄色。我们的研究表明,大黄鱼皮肤呈现金黄色时,其黄色素细胞内的色素颗粒(黄素体)呈扩散状态,而皮肤呈现白色时,黄素体则完全收缩。我们进而克隆了三个POMC基因亚型,三个亚型在大黄鱼垂体中都有表达,但唯独Lc POMC-C在皮肤中有表达。在大黄鱼腹部皮肤中存在黄色素细胞,并且只有一种黑皮质素受体-MC5R的表达。在体内和体外的实验中,经过MSH多肽处理后,黄素体的扩散程度增加,有趣的是,在避光的实验条件下,对照组的黄素体依然扩散。此外,腺苷酸环化酶(AC)激活剂(Forskolin)亦可诱导黄素体扩散,而蛋白激酶A(PKA)抑制剂(H892HCl)则抑制了黄素体的扩散。我们的研究首次表明,大黄鱼体色的黄度与黄色素细胞色素颗粒的扩散程度密切相关,皮肤表达的MSH可通过自分泌途径促进大黄鱼黄素体的扩散,暨,MSH多肽激活黄色素细胞的MC5R,并进一步触发细胞内AC-c AMP-PKA信号通路,引起黄素体扩散。由于MSH多肽具有高效诱发大黄鱼皮肤呈现金黄色的功能,我们将其命名为"黄金肽"。更多还原

【Abstract】 The Large yellow croaker Larimichthys crocea is a valuable economic mariculture fish in China, and its yellowness in skin is considered as one of the most important economic traits. However, after long-term domestication, farmed large yellow croaker is susceptible to lose its natural yellow color, presenting yellow only during the night-time. Our study revealed that the xanthosomes of xanthophores aggregated when the body color is white and dispersed when the body color is yellow. We further cloned three POMC genes in L. crocea. All these Lc POMC genes were expressed in the pituitary, but only Lc POMC-C transcripts were expressed in the skin. There were xanthophores in the ventral skin, where only one subtype of melanocortin receptor, i.e. Lc MC5 R, was expressed. After MSH peptides treatment, dispersion degree of the xanthosomes significantly increased. Interestingly, under complete dark condition, the xanthosomes of the control were still dispersed in vivo and in vitro. Forskolin, an Adenylyl cyclase(AC) activator, dispersed the xanthosomes. H 89 2 HCl, a specific inhibitor of protein kinase A(PKA) blocked α-MSH-induced xanthosome dispersion. Our study shows for the first time that the yellowness of L. crocea skin is mainly due to the dispersion degree of xanthosomes. The MSH, which was expressed in skin, could increase the dispersion degree of xanthosomes via autocrine pathway, i.e. MSH stimultes MC5 R, which further trigers AC-c AMP-PKA signal pathway to disperse xanthosomes. Since the high-efficiency function of MSH peptide in inducing the yellowness of the skin of large yellow croaker, we named it "golden peptide".更多还原