【摘要】 抗菌肽是蛙类非特异性免疫的重要组成部分,蛙类对环境变化比较敏感,但仍能分布于广泛的地理区域,抗菌肽的多样性和组成是揭示其适应机制的基础。本研究通过RT-PCR技术,从1只黑斑侧褶蛙的皮肤组织中克隆了9条不同的cDNA序列,分属5个家族:Esculentin-1、Esculentin-2、Temporin、Nigrocin-1和Nigrocin-2。其中Esculentin-1、Esculentin-2、Temporin和Nigrocin-1为阳离子抗菌肽,等电点(PI)8.72～9.63,分子量(Mw)1495.87～4862.9,预测的二级结构都具有α-螺旋结构。Nigrocin-2为新发现的一类酸性抗菌肽,等电点PI为4.0,Mw为1798.06,带1个负电荷,预测二级结构不具有α-螺旋结构,呈无规则卷曲。这9条抗菌肽cDNA来自50个阳性克隆,显示出黑斑侧褶蛙抗菌肽具多样性,特殊抗菌肽的发现也预示着黑斑侧褶蛙适应复杂多变环境、分布广泛的生理潜能,但具体功能还需进一步研究。更多还原

【Abstract】 Antimicrobial peptides(AMPs) are a major component of innate immunity of amphibians and play essential roles in amphibian survival and evolution.Frogs are sensitive to environmental changes but are widely dispersed across heterogeneous geographic regions.The composition and diversity of AMPs provide clues to their adaptive evolution.We identified 9 different AMP cDNAs from fresh skin tissue of a black spotted frog(Pelophylax nigromaculata) by using RT - PCR technology.These cDNAs were assigned to 5 families,four of which,namely Esculentin - 1,Esculentin - 2,Temporin and Nigrocin - 1,were all cationic peptides with molecular weights between 1495.87 and 4862.9,and theoretical isoelectric points(PI) between 8.72 and 9.63.All were predicted to form an a - helix in water solution.The fifth family was a novel acidic AMP first identified in amphibians,hereby named Nigrocin -2,with molecular weight 1798.06,1 net negative charge and theoretical PI of 4.0.The predicted secondary structure was a random coil in water solution.These 9 cDNAs were identified from 50 clones, demonstrating the diversity of AMPs in the black spotted frog.The identification of a special acidic AMP suggested the physiological potential of the frog to survive unusual environment factors across its large and heterogeneous range.However,the physiological function of the acidic AMP is yet to be studied.更多还原