Skin Physiology Laboratory, Department of Zoology, Centre of Advanced Study, Banaras Hindu University, Varanasi, 221005, India.
Fish Physiol Biochem. 2012 Oct;38(5):1245-56. doi: 10.1007/s10695-012-9613-5. Epub 2012 Feb 16.
The innate immune system of fish is considered first line of defense against a broad spectrum of pathogens. Being a component of innate immunity and lying at the interface between fish and the aqueous environment, skin mucus plays a frontier role in protecting fish from infections. In the present study, skin mucus of Cirrhinus mrigala, Labeo rohita, Catla catla, Rita rita and Channa punctata, inhabiting different ecological niches, was analyzed to characterize potential innate immune factors such as lysozyme, proteases, phosphatases, esterase and sialic acid. The enzyme activities were high in bottom dweller species, C. punctata and C. mrigala, and low in clean water inhabiting species, L. rohita and C. catla. An inverse relationship was observed between the level of enzyme activity and the sialic acid content in these fish species. In R. rita, however, the levels of all factors were found to be low. Zymographic analysis with labeled Micrococcus lysodeikticus revealed three isoforms of lysozyme in C. punctata and two in each species, C. mrigala, L. rohita and C. catla. In R. rita, lysozyme could not be detected. Gelatin zymography revealed that serine and metalloproteases were the major mucus proteases in all fish species investigated. In addition, trypsin-like protease and Ca(++)-specific serine proteases were observed in skin mucus. Increased knowledge of these parameters could be useful in understanding the role of skin mucus in the innate immune system of fish species inhabiting different ecological niches.
鱼类的先天免疫系统被认为是抵御广谱病原体的第一道防线。作为先天免疫的一个组成部分，位于鱼类与水相环境的界面，皮肤黏液在保护鱼类免受感染方面发挥着前沿作用。在本研究中，分析了栖息在不同生态位的鲤鱼、罗非鱼、鲤鱼、鲤鱼和斑点叉尾鮰的皮肤黏液，以表征潜在的先天免疫因子，如溶菌酶、蛋白酶、磷酸酶、酯酶和唾液酸。底栖物种 C. punctata 和 C. mrigala 的酶活性较高，而清水栖息物种 L. rohita 和 C. catla 的酶活性较低。在这些鱼类中，酶活性水平与唾液酸含量呈负相关。然而，在 R. rita 中，所有因子的水平都较低。用标记的 Micrococcus lysodeikticus 进行的酶谱分析显示，C. punctata 中有三种溶菌酶同工型，而在 C. mrigala、L. rohita 和 C. catla 中则有两种同工型。在 R. rita 中，无法检测到溶菌酶。明胶酶谱分析显示，丝氨酸和金属蛋白酶是所有研究鱼类黏液中的主要蛋白酶。此外，还观察到皮肤黏液中有胰蛋白酶样蛋白酶和 Ca(++)特异性丝氨酸蛋白酶。增加对这些参数的了解，有助于理解栖息在不同生态位的鱼类物种的皮肤黏液在先天免疫系统中的作用。
