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Dr. Michael Konopka

University of Akron

March 1st, 2019 – Spring Seminar

Time and Location: Noon in Meyerhoff Chemistry, Room 120

Host: Dr. Minji Kyoung


“Single-cell Approach to Investigating Cellular Respiration and Membrane Fluidity”

Within a bacterial population, there is significant cell-to-cell variation in respiration rates. The respiration rates of individual cells are measured with a microscope-based approach that utilizes a phosphorescent Pt-porphyrin dye as the oxygen sensor since the lifetime of the dye’s excited state depends on the oxygen concentration in the sample. Microspheres embedded with the Pt-porphyrin are loaded into microwells on a glass chip designed to isolate single cells in diffusionally sealed chambers. Monitoring the consumption of oxygen in the sealed microwells over time allows a respiration rate to be calculated for the individual cells. To investigate if the membrane fluidity is contributing to the large cell-to-cell variation in respiration rates in bacteria, the diffusion of a novel hydroxy benzothiozol pyridinium cyanine in the bacteria cytoplasmic membrane is measured by Fluorescence Recovery After Photobleaching (FRAP). Using fluorescence reporters of key genes in the type II fatty acid synthesis pathway, like fabA and fabB, and mutants affecting lipid composition of the membrane, we demonstrate that fluidity is affected by the amount of unsaturated lipids in the membrane. The fluidity of the membrane can then be related back to respiration rates.