芸苔属（Brassica）植物中microRNAs的生物信息学预测与分析

MicroRNA (miRNA) 是一类调控基因转录后表达的非编码的小分子RNA．它在生物的发育、细胞增殖、凋亡以及胁迫响应等生物过程中发挥着重要的调控作用．目前,分离和鉴定miRNA的方法主要包括实验方法（遗传筛选、直接克隆）和生物信息学方法．MiRNA存在表达丰度低，表达组织特异性，以及受特殊诱导等问题，用传统的实验法常难发现和鉴定miRNA．通过生物信息学方法在已有的各种基因库中寻找未知miRNA，大大提高了人们发现miRNA及其靶基因的效率．芸苔属（Brassica）的成员包括油菜、芜青、甘蓝等，是世界各国主要油料和食用作物．目前，油菜的miRNA的分离和鉴定工作已有文献报道，而其它的尚属空白．本文将拟南芥、水稻等植物已知的miRNA分别与芜青、甘蓝、野芥菜、黑芥菜、埃塞俄比亚芥的GSS和EST数据库进行比对搜索，采用一系列标准进行筛选，最后分别在芜青和甘蓝中预测到67个和95个miRNA．再把这些预测得到的miRNA分别与芜青和甘蓝的mRNA数据库进行比对搜索，分别找到120个和111个靶基因，除去未知功能及功能不详的，各有62个和48个靶基因．分析结果表明，上述大多数靶基因编码的产物为转录因子及重要代谢酶类，涉及植物的生长发育调控，信号转导及胁迫响应等方面．

Identify Putative MicroRNAs in Brassica Family Through Bioinformatic Analysis

MicroRNAs（miRNAs）are a newly discovered class of non-protein-coding small RNAs. Growing evidences have shown that miRNAs play multiple roles in various biological processes, including development, cell proliferation, apoptosis and stress responses. The computational approach has greatly improved the efficiency of finding novel miRNAs. Thus far, the miRNAs with specific targets in Brassica napus have been identified by computational methods. Hoeever, in other species of the Brassica family, such as Brassica rapa,Brrassica oleracea, B. juncea, B. nigra and B. carinata , similar studies have not yet been described. In this report, we started with known miRNAs from Arabidopsis, rice and other plant species to search against both expressed sequence tags (EST) and genomic survey sequence (GSS) databases to find potential miRNAs in B. rapa, B. oleracea. Following the filtering with a combination of stringent criteria, 67 and 95 potential miRNAs were detected in B. rapa and in B. oleracea, and they targeted to 62 and 48 genes respectively. Most of the targeted genes appeared to be involved in plant growth, development and stress responses according to the NCBI mRNA target information.