组蛋白翻译后修饰（PTMs）在细胞生命过程中起着重要的时空调控作用。然而目前的研究主要集中在组蛋白修饰酶结构、功能及分子机制方面，对组蛋白修饰位点自身生物学功能与意义的研究尚不多见。这主要归因于目前无法在多细胞生物中对多拷贝组蛋白基因进行遗传操作。本项目尝试将CRISPR/Cas9与Flp/FRT和phiC31重组技术相结合，在模式生物果蝇体内建立组蛋白基因簇敲除及原位组蛋白补偿系统。通过补偿系统，发现20拷贝组蛋白补偿可以让敲除突变体恢复到野生型状态。基于这一拷贝数，我们将大规模地构建所有组蛋位点突变株。通过对突变株表型的分析我们可以系统地阐明组蛋白位点的原位生物学功能和潜在调控机制。由于组蛋白密码在多细胞真核生物中结构与功能上的保守性，本项目中所有组蛋白突变果蝇模型及功能机制的探索，将为哺乳动物包括人类在内的组蛋白修饰在生殖、发育和疾病中的表观遗传学机制的探索提供直接的理论及实践依据。

Histones posttranslational modifications (PTMs) contribute a dynamic regulation role through whole cell life processes in a temporal and spatial context. Although an essential role for histone modifying enzymes in these processes is well established, defining the specific contribution of individual histone residue is less well understood. This challenge is mainly due to the paucity of suitable approaches to genetically engineer multi-copy histone genes in metazoans. We developed an efficient gene targeting method in Drosophila by combining the CRISPR/Cas9 technology, FLP/FRT and phiC31-mediated recombination. By using this system, we generate a Drosophila histone knockout (KO) line and repeatedly do rescue in vivo against this KO line. Rescue results show 20 copies of histone genes are required to generate a phenotypically wild type fly. Here, we describe a new histone mutagenesis platform in Drosophila for generating all histone mutations. Analyzing any histone genotype will allow us systematically to probe the in vivo function of these histone residues and explore their epigenetic regulation mechanism. Owing to the conservation of structure and function of histones in many metazoans, all explanations of histone-associated regulation in fly model will make us better understand epigenetic mechanisms involved in human reproduction, development and disease.