Each human cell contains around two meters of DNA tightly packaged in its nucleus. An exquisite organization is critical to ensure that the DNA can be accessed by the many important genetic processes. This organization is achieved by wrapping the DNA around millions of tiny protein spindles, forming a complex called chromatin. Chromatin governs many key cellular functions and, when malfunctions in its organization can lead to serious diseases. As of now, there exist no imaging methods that allows scientists to observe chromatin organization directly in the nucleus without seriously interfering with its local structure. In this project, two EPFL labs from different schools will develop novel methods for imaging the ultrastructure of chromatin on the level of individual genes and their regulatory regions in cells using in situ fluorescent chemical labeling, 3D nanoscopy and sequencing-based methods.