减数分裂是有性生殖过程中生殖细胞形成所必需的分裂方式, 减数分裂起始是减数分裂过程中的关键调控环节。目前，对多种高等真核生物减数分裂起始过程染色体的动态变化已有精确描述，但减数分裂起始的分子调控机制并不清楚。纤毛类原生动物嗜热四膜虫具有核的二态性，小核在减数第一次分裂前期延伸形成独特的“Crescent”结构。本研究通过嗜热四膜虫基因表达谱和生物信息学分析，筛选减数分裂时期高表达的周期蛋白基因。利用免疫荧光定位分析候选周期蛋白的定位模式；通过基因敲除、RNA干扰和基因过表达分析特异周期蛋白对四膜虫小核减数分裂“Crescent”发生的影响。通过突变体和野生型细胞减数分裂初期转录组表达差异，鉴定出周期蛋白相关基因，免疫荧光共定位和免疫共沉淀技术分析周期蛋白与候选基因之间的相互作用。由此建立四膜虫减数分裂起始的分子调控机制，为深入了解真核生物减数分裂发生的分子调控机制提供新的理论依据。

Meiosis is an essential division for the formation of germ cells during sexual reproduction, the onset of meiosis is the key regulation step during meiosis. Although there is precise description for the dynamic change of chromosomes during meiotic progress, the molecular mechanism is not clear for the process. Ciliated protozoa Tetrahymena thermophila are unicellular organism with two nuclei, a diploid micronucleus as the germ line and a polyploid somatic macronucleus. Tetrahymena forms specific elongated “Crescent” structure during the first meiotic prophase. The elongated structure is an excellent model for exploring the molecular mechanism of meiotic onset. In this study, we will first screen cyclin genes expressed highly during micronuclear meiosis stage by Tetrahymena gene expression profiles and bioinformatic analysis. Then, HA/V5/Flag/GFP-tagged cyclins mutant cells will be constructed and dynamic localization of the tagged protein will be obtained by immunofluorescence staining. The function of the cyclins will be analyzed by gene knockout, RNAi, and gene overexpression. Furthermore, cyclin interaction protein encoding genes will be identified by the comparation of transcriptome sequencing between the mutant and wild type lines. The physical interaction of different poteins will be established by co-localization and co-immunoprecipitation methods. Based on the date, the molecular regulation mechanism of the meiotic onset and micronuclear elongation will be established in Tetrahymena. The study will explore our understanding for molecular mechanism of the meiotic onset in eukaryotic cells.