基因组DNA压缩参与基因激活、基因复制和修复等多个重要的细胞生理学过程，但目前缺乏可对该过程进行高空间分辨、实时动态以及定量表征的光学方法。本项目提出并发展一种基于超分辨随机光学重构显微（STORM）和荧光寿命显微成像（FLIM）联用的基因组DNA压缩多模态光学表征方法，利用STORM方法获得荧光标记的染色质丝超分辨图像，利用基于FLIM的荧光共振能量转移（FRET）方法分析荧光标记DNA双链的相互作用，两种成像方法的结合联用将提高对DNA压缩的光学表征能力。在此基础上，利用该光学方法和平台监测和表征细胞周期不同时间染色质压缩和打开的动态变化过程，分辨染色质富含活性基因和非编码序列区域DNA压缩的不同之处，建立在细胞核中检测单链DNA位点的新型光学方法。本项目研究将建立对染色质压缩进行定量分析的STORM/FLIM多模态光学方法，对活细胞中DNA定量研究及基因活性监测具有重要科学意义。

It is well known that genomic DNA compaction is involved in a series of essential cellular physiological processes, including gene activation as well as DNA replication and repair. However, there is not any appropriate real-time dynamic optical method of monitoring the DNA compaction process in a high-resolution and quantitative way. Here, we provide a multimodal super-resolution stochastic optical reconstruction microscopy (STORM)/fluorescence lifetime imaging microscopy (FLIM) optical technique. STORM technique can provide a resolution of ~50 nm of fluorescent dye labeled chromatin fibers. In parallel, FLIM modality will be used to analyze proximity between labelled DNA strands within 1-10 nm, through the Förster Resonance Energy Transfer (FRET) mechanism. In the outcome, STORM and FLIM-FRET data sets will be mutually combined to enhance the resolution capabilities of nanoscopic imaging. With the development of the combined multimodal system, we anticipate that this STORM-FLIM super-resolution imaging will enable dynamic analysis and characterization of compacted and open chromatin structures within different stages of cell cycle. Also, we will specifically address differences in compaction between chromatin containing active genes and chromatin containing non-coding DNA sequences. Furthermore, we will apply these novel optical techniques in probing the single strand DNA in cell nucleus. In conclusion，this project will establish a new optical multimodal platform for monitoring genomic DNA compaction in a quantitative way, providing novel optical microscopy tools for quantitative studies of chromatin compaction and gene activation. These developments will be highly demanded in a broad area of quantitative cell science and applied biomedicine.