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31 March 2006
Biology Dept. Seminar Features Dr. Teplitski

The Biology Department is presenting a seminar April 6 from 11:00 a.m. - noon in Martin Hall - Room 122. The guest speaker is Dr. Max Teplitski, Assistant Professor, Soil Microbiology, Soil and Water Science Department, University of Florida. His topic is "Underground Communication: Who Listens When Bacteria Talk?" A brief synopsis of this topic is presented here:
For their infection or colonization of plant and animal hosts, many bacteria rely on a gene regulatory mechanism, called Quorum Sensing (QS). QS is the mechanism which allows bacterial populations to behave in a coordinate, multicellular fashion.

In gram negative bacteria, QS is mediated by pheromones, called N-acyl-homoserine lactones (AHLs). These AHL pheromones are perceived by cognate bacterial AHL receptor proteins, which upon binding of the pheromone dimerize and bind within regulated promoters to effect expression of the QS genes.

QS genes often play central roles in the survival of bacterial populations, and their ability to interact with other bacteria and eukaryotic hosts. Because QS is so important to the host-bacterial interactions, hosts have evolved the means to both detect the bacterial signals and respond to these bacterial signals.

Upon perception of the bacterial pheromone, legume /Medicago truncatula/, for example, differentially regulates ~ 5% of its proteins, including those with functions in defense and hormone responses. Plants produce enzymes that inactivate bacterial pheromone signals. Also, plants and algae produce compounds which affect bacterial QS in several ways: plant AHL-mimics which interact with the AHL-binding domains of the bacterial AHL receptors, and compounds that interfere with the AHL receptor folding/stability. Animal and human cell lines also specifically respond to AHLs and produce AHL-inactivating enzymes. The ecological consequences of the interference with QS is still not known.

Dr. Teplitski is currently involved in the following research projects:
  1. Quorum Sensing in Sinorhizobium meliloti and its role in symbiosis with Medicago spp
  2. Plant Quorum Sensing signal-mimics and their effect on bacterial quorum sensing during symbiosis
  3. Signaling and gene expression in coral-associated bacterial communities
  4. Genetic pathways controlling biofilm formation in g-proteobacteria
  5. Development of new techniques and tools for studying bacterial gene expression in vivo and in vitro
To view more information on Dr. Teplitski's achievements, visit the Web site Max Teplitski. Visit the JSU Biology Department's Web site for programs and interests in this field.

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