EECE Seminar - Dr. Burak Okumus

Jan 24
11:00 AM
12:00 PM
Brauer Hall, room 12

Dr. Burak Okumus, Scientist

From single molecules to single cells: individuality in biology

Abstract: Many of the low-abundance proteins are essential for survival and play critical roles, but their quantitative characterization, especially at the level of single cells, remains elusive. Since it is easy to do so, the majority of studies about noise in gene expression measure the high-abundance proteins despite the fact that they are merely enslaved by the noise. The low-abundance proteins, however, constitute the genuine sources of the noise in gene expression but are extremely challenging to quantify. To address this practical paradox, I developed methods capitalizing on microfluidics and fluorescence, on which I will elaborate during my talk. In one particular application, we demonstrated a plausible mechanism for how transient phenotypic differences can potentially lead to permanent alterations in the genome due to the extreme scarcity of a DNA repair enzyme (~1.5 molecules/cell on average). Since the bacterial genome [and physiology] is a network with complex system characteristics and emergent behavior, some of the low-abundance proteins with key regulatory roles are arguably the ultrasensitive nodes of the network – where small changes can lead to tipping points, followed by abrupt changes in the state of the system. I will also discuss how microfluidic methods present unprecedented opportunities for single-cell analysis, for instance by enabling isolation of individual cells after the long-term monitoring of their dynamic behavior. This allowed us to identify mutations that led to significant improvement of various synthetic biological oscillators, rendering them with ultra-precise periods that are sustained over prolonged durations.