中文摘要：

为在斑马鱼中获得特异且高效的基因敲除，多个实验室独立人工合成了序列彼此不一的Cas9cDNA序列，并克隆入不同的体外转录载体。本文选取两种斑马鱼密码子优化的Cas9编码序列（zcns9-6z和zCas9_wc），对斑马鱼胚胎中的7个基因（外源egfp及内源chd、hbeg）Ca、th、eeflalb、tyr、tcJTlla）分别进行敲除，通过PCR产物测序、克隆测序和表型分析比较了两种Cas9的敲除效率。结果发现，zCas9-wc在各种情况下都显现出较高的敲除效率，而zCas9_bz的效率相对较低。

英文摘要：

Recent years have witnessed the rapid development of the clustered regularly interspaced short palin- dromic repeats/CRISPR-associated protein（CRISPR/Cas9）system. In order to realize gene knockout with high effi- ciency and specificity in zebrafish, several labs have synthesized distinct Cas9 eDNA sequences which were cloned into different vectors. In this study, we chose two commonly used zebrafish-codon-optimized Cas9 coding sequences （zCas9_bz, zCas9wc） from two different labs, and utilized them to knockout seven genes in zebrafish embryos, in- eluding the exogenous egfp and six endogenous genes （chd, hbegfa, th, eeflalb, tyr and tcfTlla）. We compared the knockout efficiencies resulting from the two zCas9 coding sequences, by direct sequencing of PCR products, colony sequencing and phenotypic analysis. The results showed that the knockout efficiency of zCas9_wc was higher than that of zCas9_bz in all conditions.