中文摘要：

载脂蛋白C-Ⅰ（Apolipoprotein C,ApoC-Ⅰ）是载脂蛋白家族中分子质量最小的成员,在脂类摄入、转运和分泌中发挥重要作用。通过c DNA文库随机测序获得了香鱼（Plecoglossus altivelis）ApoC-Ⅰ（Pa ApoC-Ⅰ）全长c DNA序列。Pa ApoC-Ⅰ由574个核苷酸组成,包含一个长度267 bp的开放阅读框,编码88个氨基酸,预测分子量为10.08 ku,N-末端1-20位氨基酸残基为信号肽序列。氨基酸序列多重比对结果表明,Pa ApoC-Ⅰ与虹鳟（Oncorhynchus mykiss）ApoC-Ⅰ同源性最高,为67.0%;系统进化树分析表明,哺乳动物、爬行动物、两栖类和鱼类的ApoC-Ⅰ分别成簇,Pa ApoC-Ⅰ位于鱼类ApoC-Ⅰ簇中,且与虹鳟ApoC-Ⅰ进化相关性最高。基因组结构分析表明,Pa ApoC-Ⅰ基因组DNA序列由2个内含子和3个外显子组成。实时荧光定量PCR（quantitative real-time PCR,qRTPCR）结果显示,Pa ApoC-ⅠmRNA表达量在香鱼肝组织中最高,镉胁迫后在肝、脾、肾和肠中显著上调,在鳃中表达量显著下调。综上,Pa ApoC-Ⅰ的表达与镉胁迫密切相关,可能作为水环境中重金属镉污染的生物分子标记。研究结果为进一步研究鱼类ApoC-Ⅰ的功能及其在重金属胁迫中的作用机制提供了基础资料。

英文摘要：

ApoC-Ⅰ（ Apolipoprotein C-Ⅰ） is the smallest member of the apolipoprotein family,which plays important roles in lipid uptake,secretion and transport. Here,we obtained the full-length c DNA sequence of ayu（ Plecoglossus altivelis） ApoC-I gene（ Pa ApoC-Ⅰ） through random sequencing of c DNA library. The c DNA sequence of Pa ApoC-Ⅰis 574 nucleotides,consisting of a 267 bp open reading frame that encodes a protein of 88 amino acids with a deduced molecular mass of 10. 08 ku. The N-terminus of Pa ApoC-Ⅰcontains a predicted signal peptide of 20 amino acids. Multiple sequence alignment of complete amino acid sequences showed that Pa ApoC-Ⅰshared the highest amino acid sequence identity（ 67. 0%） with that of rainbow trout（ Oncorhynchus mykiss）.Phylogenetic tree analysis revealed that ApoC-Ⅰfrom mammals,reptiles,amphibians and fish formed different clusters,and Pa ApoC-Ⅰfalled into the fish ApoC-Ⅰcluster and was most closely related to that of rainbow trout. Genome structure analysis showed that Pa ApoC-Ⅰcontained three exons and two introns. Quantitative real-time PCR（ qRT-PCR） analysis showed that Pa ApoC-ⅠmRNA had the highest expressional level in ayu liver. Upon cadmium（ Cd） exposure,Pa ApoC-I transcripts were significantly up-regulated in ayu liver,spleen,kidney and intestine,and were significantly down-regulated in ayu gill. In summary,our present study demonstrated that a tight relationship between the Pa ApoC-Ⅰ expression and Cd stress,and it can be a potential biomarker for Cd exposure in aquatic organisms. The results would provide the basic data for further studying the function of fish ApoC-Ⅰ and its mechanism in fish response to heavy metal stress.