Measuring and Modeling How Clocks in Single Cells Communicate: an interdisciplinary apporach

University Of Georgia Research Foundation Inc, Athens GA

Investigators

Abstract

Oscillators, by virtue of their periodic behavior, provide a way to tell time, as illustrated by the movement of a clock's pendulum. The study of coupled oscillators and their mutual synchronization has remained a problem central to physics for centuries, but has only recently captured the imagination of biologists. One example of synchronized oscillators are the biological clocks found in living cells. Biological clocks are pervasive in their effects from genes to ecosystems. Biological clocks affect the health of humans, animals and plants and they are being engineered for timed delivery of therapeutics, algal bioreactors for biofuel production, and crop improvement. The clock, through its light entrainment feature, impacts the genetic dynamics of bacterial assemblages in the world's oceans and hence may affect carbon cycling in marine ecosystems. Understanding how cell populations synchronize their clock oscillations, to give rise to a functioning "biological clock", is the central focus of this project. The project will also develop an innovative interdisciplinary "Clock Collaboratorium" graduate student research training course that will make extensive use of cyber-learning tools. Investigators will invite undergraduate and high school students to their labs to work on research related to this project. Recent evidence suggests that single-cell oscillators of the filamentous fungus Neurospora crassa (N. crassa) are stochastic on a single-cell level, while measurements on populations of millions of cells indicate that their clocks are synchronized. In order to understand this synchronization, a novel droplet microfluidics platform is deployed for high-throughput, high-precision measurements on a controlled number of living N. crassa cells. Single-cell measurements will confirm whether circadian rhythms exist on a single-cell level and the extent of stochasticity. Multi-cell experiments will probe communications and synchronization between single-cell clock oscillators. Signaling molecules responsible for synchronization will be identified using nuclear magnetic resonance on exo-metabolites from living cells. Stochastic resonance, a fundamental concept from non-linear-systems physics, will be tested as a possible clock synchronization mechanism, against multi-cell measurements, using novel ensemble simulation modeling approaches. This project is is expected to advance systems biology research on clock systems through (1) tight coupling of modeling and experimentation, and (2) opening up a new frontier by pushing the scale of measurements to single cells. A detailed understanding of the clock's single-cell regulation in N. crassa will provide new insights into clock mechanisms, regulatory clock controls, and physiological consequences in other organisms, ranging from plants to humans.