Nanoscopic imaging of chromatin topology utilizing intrinsic fluorescence from unmodified nucleic acids (Conference Presentation)

Abstract

Imaging the nanoscale intracellular structures formed by nucleic acids, such as chromatin, in non-perturbed, structurally and dynamically complex cellular systems, will help improve our understanding of biological processes and open the next frontier for biological discovery. Current optical super-resolution fluorescence techniques require exogenous labels that may disrupt cell function and alter the subdiffractional macromolecular structures they are used to visualize. As a means for label-free optical super-resolution imaging, we examined the discovery of stochastic fluorescence switching of unmodified nucleic acids under visible light illumination. Utilizing this phenomenon and a single-molecule photon localization approach we generated subdiffraction-resolution images down to ~20nm using intrinsic fluorescence from nucleic acids. Specifically, the nanoscale organization of interphase nuclei and mitotic chromosomes were imaged. Using such a method for visualization, we performed a quantitative analysis of the DNA occupancy level and a subdiffractional analysis of the chromosomal organization. These experiments demonstrate a new method for visualizing the nanoscopic features of macromolecular structures composed of nucleic acids without the need for exogenous labels.