核酶是具有催化功能的核酸分子，作为一个全新的分子工具，核酶在生物分析、医学诊断、纳米技术以及基因治疗等方面发挥着越来越大的作用；由于绝大多少核酶通过体外筛选获得，而体外筛选过程冗长而繁琐，而且通过体外筛选获得的核酶在体内的表现会出现较大的差异。本项目拟发展新的基于细菌为载体的体内核酶筛选进化体系，以期快速获取能够直接在体内工作核酶；以筛选能够在细胞内高效剪切目的mRNA的脱氧核酶为目标，分子间的反应为核酶工作方式，抗生素抗性为进化压力，通过细菌的连续培养驱动核酶的进化，最终获得催化能力更为高效的全新核酶，为体内基因的调控和疾病治疗提供更强大的分子工具。

As a new molecular tool, ribozyme and DNAzyme are functional nucleic acid sequences with catalytic ability, which have been applied in medical diagnosis, nano technology, genetic therapy and so on. Most of those catalytic nucleic acids were obtained through in vitro selection, which is time-consuming and tedious. Moreover, the DNAzyme obtained from in vitro selection reveals different catalytic ability when applied in vivo. This project is proposed to develop a new in vivo selection technique based on continuous cultivation of bacteria to obtain the DNAzyme in short period of time, which could effectively work in vivo directly. The RNA-cleaving DNAzyme will be selected through this method. To get the high efficient DNAzyme for the future application of genetic manipulation and therapy in vivo, the cleaving reaction will be carried out in the intermolecular way, and the antibiotic resistance in the process of continuous cultivation of bacteria is the pressure of evolution.