General assembly dynamics

　　On May 30th, at the invitation of the 19th Academician Conference of China Academy of Sciences, Xie Xiaoliang, a foreign academician of Chinese Academy of Sciences, academician of American Academy of Sciences and named professor of Mallinckrodt in the Department of Chemistry and Chemical Biology of Harvard University, paid an academic visit to the Institute of Biophysics, and wrote the following questions.From Single Molecule Biology to Single Cell GenomicsLecture report of. The report was presided over by Xu Ruiming, director of the Institute of Biophysics.

　　Xie Xiaoliang first introduced the pioneering work of monomolecular enzymology, and explained the characteristics of enzyme’s catalytic function at the monomolecular level. Xie Xiaoliang’s research group used single molecule fluorescence technology to study the expression of protein in bacteria, and analyzed the gene expression in Escherichia coli at the level of single cell. It was found that the expression of protein in a single cell was random. The effect of DNA loops on the transcription process of genes was studied at the single molecule level. It was found that DNA loops would hinder the transcription in space, and when Gyrase gyrase did not exist, the forward supercoiled structure of DNA would slow down the speed of transcription initiation and extension, which eventually led to the inhibition of transcription initiation. Through these studies, Xie Xiaoliang’s research group found that the phenomenon of Transcription Bursting was caused by the shedding and recombination of Gyrase from DNA, and the accumulation and elimination of the forward supercoiled structure of the corresponding DNA.

　　Xie Xiaoliang also introduced Malbac (Multiple Annealing and Looping Based Amplification Cycles) method invented by his research group, and the single cell genome sequencing of human sperm cells completed by this method. Xie Xiaoliang’s research group also improved the accuracy of single-cell genome sequencing detection by META-method; MALBAC-DT (Malbac-Digital Transcriptome) method was developed to detect transcription-related modules (CTM) within the genome, and the detection efficiency was increased by 50%. Using single cell DIP-C technology, the 3D structure of human diploid cell genome was obtained, and the resolution could reach 100nm and 20kb. It was found that two X chromosomes produced different 3D structures due to different activity states. By analyzing the 3D genome structure of olfactory nerve cells, it was found that there were obvious differences between olfactory receptor-related genes and control cells. By studying the 3D genome structure of different cell types at the single cell level, it is found that different cell types have different 3D genome structures.

　　The report is rich in content, clear in logic, vivid in explanation and rich in academic atmosphere. Participants asked questions and interacted with Xie Xiaoliang on issues of interest to them. After the report, Xie Xiaoliang had a discussion with the researchers of the Institute of Biophysics, and conducted in-depth exchanges and discussions on issues of common interest.

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