Single-Cell Biophysics: Measurement, Modulation, and Modeling

Single-Cell Biophysics: Measurement, Modulation, and Modeling

Monday Speaker Abstracts

Single-Molecule Studies of Cas9 Search Kinetics in Living Cells Daniel Jones, Prune Leroy, Cecilia Unosson, David Fange, Johan Elf . Uppsala University, Uppsala, Sweden.

Cas9-based DNA targeting is radically different from that of transcription factors. Cas9 can be programmed by a guide RNA to target any sequence. We have studied how much time it takes to located a singel target sequence in a living cell using single molecule fluorescence microscopy. We also measure how long time the bound dCas9 stays at a target sequences and what implications this has for repression of a targeted gene.

Decoding Chromatin Organization with Superresolution Microscopy Melike Lakadamyali 1,2 . 1 ICFO-Institute of Photonic Sciences, Barcelona, Spain, 2 University of Pennsylvania, Philadelphia, PA, USA. Nucleosomes help structure chromosomes by compacting DNA into fibers. Chromatin organizationin the kilo-to-megabase length scales plays an important role for regulating gene expression. However, these small length scales have been impossible to visualize using conventional microscopy methods, hence making it challenging to decipher the nanoscale organization of chromatin inside the nucleus. To gain insight into how nucleosomes are arranged in vivo, we have been using quantitative super-resolution nanoscopy to visualize and determine the organization of the chromatin fiber in single nuclei. We have been able to correlate the nanoscale organization of chromatin to cell state, enabling us to identify the level of pluripotency as well as the differentiation state of different cell types.

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