DNA Liquids: Precision Physics and Imaginary Biology
Prof. Omar Saleh, University of California, Santa Barbara
Biological cells have evolved to create elaborate internal partitions, which allow them to control biochemical and genetic processes in space and time. Increasing evidence indicates that some of these partitions are created by the phase separation of large biological molecules, in which complex mixtures of RNA and protein associate to form dense globules (‘condensates’), frequently with liquid-like properties. We study the underlying physical aspects of such biomolecular phase separation processes, particularly by performing experiments with a model system of ~10 nm DNA particles. This system is highly tunable and experimentally tractable, permitting precision measurements of various kinetic phenomena associated with phase separation. We have further developed techniques to use the system to create multiple condensate phases that form structures and patterns on micron to millimeter scales. These scales transcend what is strictly relevant within the cell; instead they represent what might be called an ‘imaginary biology’ of diverse, locally disordered biomolecular phases that form emergent long-range structures
Bio:
Professor Omar A. Saleh is a physicist and materials scientist with broad expertise in biomolecular and polymer science. Saleh received his B.S. in Physics from MIT in 1997, and his Ph.D. in Physics from Princeton in 2003. His graduate studies were supported by a Hertz Fellowship. He was a post-doctoral fellow at the École Normale Supérieure in Paris, France, where he developed single-molecule experimental techniques to study motor protein/DNA interactions. He came to UC Santa Barbara in 2005, where he is now a full professor with appointments in the Materials and Physics Departments, along with a minority appointment in the Biomolecular Science and Engineering (BMSE) Program. He served as Director of the BMSE program from 2013 to 2017, and was an elected member of the Executive Committee of the Division of Biological Physics of the American Physical Society from 2013 to 2016. Since the summer of 2023, he has been the Chair of the Materials Department. Saleh's research is focused on the molecular physics underlying biological systems, with research efforts associated with nucleic acids, protein/DNA interactions, motor proteins, biomolecular elasticity, and self-assembled biomolecular systems. His research achievements were recognized by an NSF CAREER award in 2008, by a Bessel Research Award from the Alexander von Humboldt Society in 2017, and by his selection as a Fellow of the American Physical Society in 2019 by the Division of Biological Physics.