三种四膜虫全基因组N6-甲基腺嘌呤的鉴定及其功能进化

DNA甲基化在转录调控、DNA复制等多个方面具有重要作用。目前，基于全基因组水平的DNA甲基化研究主要集中在高等真核生物中，低等真核生物中很少，关注5-甲基胞嘧啶(m5C)的多，着眼其它甲基化修饰的少，其中，N6-甲基腺嘌呤（m6A）修饰是高等真核生物中次要的甲基化修饰，却是很多原核及单细胞真核生物（含原生动物）中主要的DNA甲基化修饰类型。针对目前尚缺乏对纤毛类原生动物全基因组水平m6A分布、功能和进化的了解，本项目在纤毛虫中以四膜虫属三个种为研究对象，在鉴定并绘制单碱基分辨率全基因m6A图谱的基础上，对m6A具有的基序、分布周期性及其与核小体、组蛋白修饰、转录起始、剪接及DNA复制起点的关系进行分析，考察m6A的功能。通过对不同时期及不同四膜虫中m6A的功能进行比较，探讨m6A的功能进化。项目的实施，将填补纤毛虫中m6A甲基化组研究的空白，对理解真核生物m6A的功能进化具有重要意义。

DNA methylation have important roles in gene expression regulation, DNA replication, etc. Currently, genome-wide DNA methylation studies mainly focused on 5-Methylcytosine (m5C) in higher eukaryotes, and few have been performed for other types of DNA methylations in lower eukaryotes. N6-methyladenosine (m6A) is a DNA methylation which have been reported as the main type of DNA methylation in many prokaryotes and single-celled eukaryotes (including protozoan), but not the main DNA methylation in many higher eukaryotes. In view of lacking of knowledge of genome-wide m6A distribution, function and its evolution, this project proposes to identify the genome-wide m6A distribution at single nucleotide resolution in three ciliated Tetrahymenas, and investigate the function of m6A based on the analysis of motif, periodic distribution and correlation with the nucleosome, histone modification, transcription initiation, splicing and DNA replication initiation, then further explore the function evolution of m6A by comparing the function changes in three Tetrahymenas at different stages. This project will fill the gap of absent the genome-wide m6A study in ciliates and greatly improve our understanding of the functional evolution of m6A in eukaryotes.