中文摘要：

siRNA和miRNA的沉默机制是生物基因调控的重要手段之一.小干扰RNA（small interfering RNA,siRNA）是RNA干扰的引发物,激发与之互补的目标mRNA沉默.非编码RNA中的微小RNA（microRNA,miRNA）,能够识别特定的目标mRNA,通过与mRNAs的3＇非翻译区结合,影响该目标蛋白的翻译水平.siRNA和miRNA的基因调控机制对生物学研究及疾病的病因和治疗等有直接影响.本文主要对siRNAs和miRNAs的生物起源及沉默机制进行比较性论述：提出Dicers酶蛋白、Ago蛋白以及20 nt～25 nt的双链RNAs的3类大分子是RNA沉默的特征结构,并进行了说明性论述;总结性叙述了siRNA和miRNA的2类小分子经典沉默机制,并提出其异同点.最后,本文根据近期研究进展,对siRNA和miRNA的生物起源及沉默机制提出了新的疑问.

英文摘要：

Gene silencing via microRNA（miRNA） expression and small interference RNA（siRNA） become important methods in for gene regulation.SiRNA-based RNA interference mediates the gene silencing by sequence complementary with target mRNA,whereas miRNA negatively regulates the gene expression at the post-transcriptional level through complementary sites at the 3′ untranslated regions of the target genes.The siRNA and miRNA regulation of gene expression has wide implications for the understanding of biology,as well as for disease etiology and treatment.Three sets of macromolecules,Dicers,Agos and 20 nt~25 nt RNA duplex,are introduced as the signature components of RNA silencing,two types of the classic silencing mechanisms of siRNA and miRNA are described.This review also compares the differences and discusses about the new arguments about the biological origins and silencing mechanisms of siRNA and miRNA.