Event Title

Designing a Laboratory Ercise to Illustrate Ionophores as Membrane Probes

Location

MSU Ballroom

Start Date

18-4-2016 10:00 AM

End Date

18-4-2016 11:30 AM

Student's Major

Biological Sciences

Student's College

Science, Engineering and Technology

Mentor's Name

Timothy Secott

Mentor's Department

Biological Sciences

Mentor's College

Science, Engineering and Technology

Description

Ionophores are lipophilic molecules that transport ions down a concentration gradient and across cell membranes. As such, they are important tools for studying membrane potentials and solute transport across cell membranes. However, the function of ionophores and their uses are frequently a source of confusion to students studying microbial physiology. The purpose of this investigation was to design a laboratory ercise for BIOL 476, Microbial Physiology and Genetics, that could improve student appreciation and understanding of the utility of ionophores. The effect of ionophores on membrane potential was indicated using the fluorescent dye DiOC2 in a flow cytometry assay. At high intracellular concentrations, DiOC2 fluoresces green, indicating a high membrane potential. At low concentrations, DiOC2 fluoresces red. Escherichia coli was grown in minimal medium containing various concentrations of potassium chloride and then incubated with the fluorescent dye DiOC2, with or without valinomycin, a potassium ionophore. In the presence of valinomycin, potassium ions were expected to leave the cell, causing an increase in membrane potential and a red shift in cells. However, preliminary experiments yielded results opposite that of our prediction. Higher internal concentrations of potassium chloride are currently being evaluated in an attempt to determine the concentration range that results in a red shift.

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Apr 18th, 10:00 AM Apr 18th, 11:30 AM

Designing a Laboratory Ercise to Illustrate Ionophores as Membrane Probes

MSU Ballroom

Ionophores are lipophilic molecules that transport ions down a concentration gradient and across cell membranes. As such, they are important tools for studying membrane potentials and solute transport across cell membranes. However, the function of ionophores and their uses are frequently a source of confusion to students studying microbial physiology. The purpose of this investigation was to design a laboratory ercise for BIOL 476, Microbial Physiology and Genetics, that could improve student appreciation and understanding of the utility of ionophores. The effect of ionophores on membrane potential was indicated using the fluorescent dye DiOC2 in a flow cytometry assay. At high intracellular concentrations, DiOC2 fluoresces green, indicating a high membrane potential. At low concentrations, DiOC2 fluoresces red. Escherichia coli was grown in minimal medium containing various concentrations of potassium chloride and then incubated with the fluorescent dye DiOC2, with or without valinomycin, a potassium ionophore. In the presence of valinomycin, potassium ions were expected to leave the cell, causing an increase in membrane potential and a red shift in cells. However, preliminary experiments yielded results opposite that of our prediction. Higher internal concentrations of potassium chloride are currently being evaluated in an attempt to determine the concentration range that results in a red shift.

Recommended Citation

Obrant, Victoria. "Designing a Laboratory Ercise to Illustrate Ionophores as Membrane Probes." Undergraduate Research Symposium, Mankato, MN, April 18, 2016.
http://cornerstone.lib.mnsu.edu/urs/2016/poster-session-A/14