*********************************
There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
*********************************
Atlanta, GA | Posted: May 17, 2016
Summary Sentence:
Dr. Sam Brown Awarded $600K
Full Summary:
No summary paragraph submitted.
Sam BrownDr. Sam Brown, Associate Professor of Biology, was just awarded a $600K, 3 year grant from the Simons Foundation for a project entitled “How do quorum-sensing bacteria sense and respond to their social and physical environment?”This project investigates collective decision making in bacteria by exploring how bacteria collectively sense and respond to their environment via a form of cell-cell communication known as quorum-sensing (QS). Despite the widespread interest in QS from molecular mechanisms to social evolution and pathogen control, there is still controversy over the basic evolutionary function of QS – in short, why do bacteria use QS? The standard answer is that cells produce extracellular signals to serve as a proxy for cell density – more signal implies more bacteria. However, inferences to density can be confounded as signal concentration will also vary with changes in the physical environment (diffusion, flow) and other aspects of social organization (spatial patterning, genotypic mixing), leading to a list of alternative hypotheses (e.g. diffusion, efficiency, and genotype sensing).
Current functional hypotheses and mathematical models focus on the limits of inference to physical and/or social environmental variation, given the production and sensing of a single signal type. However, molecular characterization of QS systems often reveals the use of
multiple distinct extracellular signal molecules. To overcome this persistent gap between
functional hypotheses and molecular mechanism we will develop and test theory on the functional roles and limits of multi-signal QS, using the widely studied environmental generalist microbe Pseudomonas aeruginosa (PA). Our central hypotheses are that QS bacteria can (1) simultaneously resolve their social and physical environment, via non-linear processing of multiple signals with differing environmental properties and (2) use simple signal-mediated rules to limit collective behaviors to clonal high density, low diffusion, low flow environments. The proposed research will leverage Georgia Tech’s expertise in spatial math modeling, ‘lab-on- a-chip’ environmental manipulation, high-throughput microbial imaging and evolutionary microbiology.
