团头鲂黏蛋白基因Muc5b克隆及表达分析

摘要：黏液（mucus）在鱼体防御外界病原侵袭、信息传递、调节渗透压等方面具有重要作用。黏蛋白（mucin）作为黏液的基础骨架组分，与其相关的研究正受到广泛的关注。在本研究中，作者克隆获得团头鲂（Megalobrama amblycephala）Muc5b mRNA 的部分序列3895 bp，并通过qRT-PCR分析了Muc5b在团头鲂不同组织的表达分布及其在捕捞应激后在鳃和表皮中的表达变化。序列分析结果显示，团头鲂Muc5b与鲤等脊椎动物的Muc5b有较高的同源性，其N端含有黏液蛋白特异性结构域：三个VWD区域，三个C8区域，二个TIL区。组织表达分析结果表明，Muc5b在鳃和表皮表达量相对较高，在脑、脾、肾中表达水平较低，在肝、肠道几乎不表达。捕捞应激后1 h时鳃中Muc5b显著降低（P < 0.05），24 h时恢复初始水平；表皮中4 h时Muc5b显著上升（P < 0.05），24 h时恢复到初始水平。

Cloning and Expression of Muc5b in Megalobrama amblycephala and Muc5b Expression Alteration after Catching Stress

Abstract : Mucus plays an important role in protecting fish against pathogen invasion, signaling events, regulating osmotic pressure and so on. As mucins are the important skeleton components of the mucus, the researches on fish mucins have catch wide attention. However, few studies have been reported on fish mucin gene characteristic and expression pattern. In this study, Megalobrama amblycephala Muc5b mRNA(3895 bp length) was cloned and its tissues expression was analyzed by qRT-PCR. The result showed that sequence of M. amblycephala Muc5b had high homology with other vertebrates, and its N-terminal of predicted amino acid sequence contained several non-PTS region domains: three VWD domains, three C8 domains and two TIL domains(Fig.2). Gene expression indicated that relatively higher expression of Muc5b in gills and skin, lower expression in brain, spleen, kidney, almost no expression in liver and intestine(Fig.4). In addition, variation of Muc5b expression was detected in gills and skin after catching stress. Muc5b expression was significantly reduced in the gills (t-test, P < 0.05) at 1h after catching-stress, and recovered to initial level at 24h; On the contrary, Muc5b expression was increased in the skin at 4h(t-test, P < 0.05), then recovered to the initial level(Fig.6). Thus, the Muc5b expression can be influenced by catching-stress.