DNA dynamics in crowded cell-sized droplets*

Understanding the transport and conformational dynamics of biological macromolecules such as DNA in crowded and confined environments is critical to understanding biological processes such as viral infection, liquid-liquid phase separation, and transcription. Here we investigate the dynamics, conformations, and organization of DNA molecules confined in cell-sized droplets and crowded by dextran polymers. Specifically, we use differential dynamic microscopy to measure ensemble DNA dynamics and single-molecule conformational tracking to measure DNA trajectories, shapes, and localization. We directly connect these measurements to the microrheological properties of the crowded, confined environment by performing similar measurements with  microspheres. We determine the impact of droplet size and crowding conditions, as well as DNA length and topology, on the measured transport and structural properties.