中文摘要：

组蛋白H3/H4的分子伴侣Asf1（anti-silencing factor 1）,参与依赖DNA复制及不依赖DNA复制的核小体装配,同时参与转录调控、基因沉默以及DNA损伤修复等过程.在不同生物中,Asf1具有功能的保守性和多样性.嗜热四膜虫ASF1（TTHERM_00442300）基因编码的蛋白质含有保守的N端结构域和酸性的C端结构域.N端结构域同源序列进化树分析表明,Asf1进化与物种进化一致.实时荧光定量PCR表明,ASF1在四膜虫营养生长、饥饿及有性生殖时期均有表达,且在有性生殖4～6 h转录水平达到最高.免疫荧光定位分析表明,HA-Asf1在营养生长时期以及有性生长时期定位于功能大核和小核中,而在凋亡的大核中信号消失.过表达ASF1导致大核及小核变大,抑制细胞增殖.敲减ASF1后会导致大核形态异常,小核缺失.结果表明,ASF1表达对细胞核的形态和结构维持发挥重要的调控作用.

英文摘要：

Histone H3/H4 chaperone Asf1（anti-silencing factor 1） is involved in DNA replicationdependent and DNA replication-independent nucleosome assembly and participates in transcriptional regulation,gene silencing and DNA damage repair. Asf1 has functional conservation and diversity in different organism. The Tetrahymena thermophila ASF1（ TTHERM_00442300） encodes protein containing the conserved N-terminal domain and the acidic C-terminal domain. Phylogenetic analysis showed that Asf1 is evolutionarily conserved protein in Tetrahymena. Real-time PCR showed that ASF1 was expressed in vegetative growth,starvation stage and highly expressed at 4 ～ 6 h conjugation stage. Immunofluorescence staining showed that HA-Asf1 located in the parental macronucleus,micronuclei and developing anlagen,but disappeared in the apoptotic old macronucleus during conjugation stage. Overexpression of ASF1 gene led to the larger macronucleus and micronucleus and inhibited cell proliferation. Knockdown of ASF1 gene led to abnormal macronucleus and lost of the micronucleus. The results showed that Asf1 plays an important role in maintaining macronucleus and micronucleus stability in Tetrahymena.