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Nonlinear impedance of whole cells near an electrode as a probe of mitochondrial activity.

Palanisami A, Mercier GT, Fang J, Miller JH - Biosensors (Basel) (2011)

Bottom Line: By simultaneously measuring the bulk media and electrode interface voltages of a yeast (Saccharomyces cerevisiae) suspension subjected to an AC voltage, a yeast-dependent nonlinear response was found only near the current injection electrodes.Computer simulation of yeast near a current injection electrode found an enhanced voltage drop across the yeast near the electrode due to slowed charging of the electrode interfacial capacitance.This voltage drop is sufficient to induce conformation change in membrane proteins.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 77204, USA. apalanisami@uh.edu.

ABSTRACT
By simultaneously measuring the bulk media and electrode interface voltages of a yeast (Saccharomyces cerevisiae) suspension subjected to an AC voltage, a yeast-dependent nonlinear response was found only near the current injection electrodes. Computer simulation of yeast near a current injection electrode found an enhanced voltage drop across the yeast near the electrode due to slowed charging of the electrode interfacial capacitance. This voltage drop is sufficient to induce conformation change in membrane proteins. Disruption of the mitochondrial electron transport chain is found to significantly change the measured nonlinear current response, suggesting nonlinear impedance can be used as a non-invasive probe of cellular metabolic activity.

No MeSH data available.


Related in: MedlinePlus

(a) Current distortion reconstruction from ρ+ (dashed) and ρ− yeast under O2 saturated conditions (data taken immediately after insertion of yeast into O2 saturated media) and ρ+ under O2 depleted conditions (data taken 6 min after insertion of yeast into media). The O2 saturated ρ+ data is clearly phase shifted to the right. (b) The change in the current distortion of ρ+ yeast as a function of time. The reconstruction at 0 min (100% O2 saturation) is used as a baseline subtraction. At 3.5 min, all the O2 has been consumed by the yeast. To increase the resolution of these data, the gain was increased on the analog to digital converter, leading to clipping of the recorded outer electrode voltage; thus the voltage sine wave across the outer electrodes appears clipped in the figure. (c) The time shift of the peak of the 3rd harmonic current distortion as compared to the peak of the fundamental outer electrode voltage (peaks are near time 0 in (a)) for 3 replicates of ρ+ yeast. As the O2 is consumed, the 3rd harmonic advances with respect to the fundamental. (d) Similar to (c) except the media now contains 10 μM antimycin. The time shift of the antimycin treated ρ+ yeast is similar to the ρ+ yeast in the anaerobic (fermenting) condition in (c).
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biosensors-01-00046-f003: (a) Current distortion reconstruction from ρ+ (dashed) and ρ− yeast under O2 saturated conditions (data taken immediately after insertion of yeast into O2 saturated media) and ρ+ under O2 depleted conditions (data taken 6 min after insertion of yeast into media). The O2 saturated ρ+ data is clearly phase shifted to the right. (b) The change in the current distortion of ρ+ yeast as a function of time. The reconstruction at 0 min (100% O2 saturation) is used as a baseline subtraction. At 3.5 min, all the O2 has been consumed by the yeast. To increase the resolution of these data, the gain was increased on the analog to digital converter, leading to clipping of the recorded outer electrode voltage; thus the voltage sine wave across the outer electrodes appears clipped in the figure. (c) The time shift of the peak of the 3rd harmonic current distortion as compared to the peak of the fundamental outer electrode voltage (peaks are near time 0 in (a)) for 3 replicates of ρ+ yeast. As the O2 is consumed, the 3rd harmonic advances with respect to the fundamental. (d) Similar to (c) except the media now contains 10 μM antimycin. The time shift of the antimycin treated ρ+ yeast is similar to the ρ+ yeast in the anaerobic (fermenting) condition in (c).

Mentions: A biological component to the nonlinearity can be seen by comparing the current distortion response from ρ+ and ρ- yeast in oxygen saturated media (Figure 3(a)). The distortion response of the ρ− yeast is advanced relative to the ρ+ strain. As the media was identical in both experiments, the difference must come from the yeast. Furthermore, when the chamber is sealed and the ρ+ yeast are allowed to consume all the oxygen, the ρ+ current distortion advances to the same phase as the ρ− current distortion.


Nonlinear impedance of whole cells near an electrode as a probe of mitochondrial activity.

Palanisami A, Mercier GT, Fang J, Miller JH - Biosensors (Basel) (2011)

(a) Current distortion reconstruction from ρ+ (dashed) and ρ− yeast under O2 saturated conditions (data taken immediately after insertion of yeast into O2 saturated media) and ρ+ under O2 depleted conditions (data taken 6 min after insertion of yeast into media). The O2 saturated ρ+ data is clearly phase shifted to the right. (b) The change in the current distortion of ρ+ yeast as a function of time. The reconstruction at 0 min (100% O2 saturation) is used as a baseline subtraction. At 3.5 min, all the O2 has been consumed by the yeast. To increase the resolution of these data, the gain was increased on the analog to digital converter, leading to clipping of the recorded outer electrode voltage; thus the voltage sine wave across the outer electrodes appears clipped in the figure. (c) The time shift of the peak of the 3rd harmonic current distortion as compared to the peak of the fundamental outer electrode voltage (peaks are near time 0 in (a)) for 3 replicates of ρ+ yeast. As the O2 is consumed, the 3rd harmonic advances with respect to the fundamental. (d) Similar to (c) except the media now contains 10 μM antimycin. The time shift of the antimycin treated ρ+ yeast is similar to the ρ+ yeast in the anaerobic (fermenting) condition in (c).
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4264341&req=5

biosensors-01-00046-f003: (a) Current distortion reconstruction from ρ+ (dashed) and ρ− yeast under O2 saturated conditions (data taken immediately after insertion of yeast into O2 saturated media) and ρ+ under O2 depleted conditions (data taken 6 min after insertion of yeast into media). The O2 saturated ρ+ data is clearly phase shifted to the right. (b) The change in the current distortion of ρ+ yeast as a function of time. The reconstruction at 0 min (100% O2 saturation) is used as a baseline subtraction. At 3.5 min, all the O2 has been consumed by the yeast. To increase the resolution of these data, the gain was increased on the analog to digital converter, leading to clipping of the recorded outer electrode voltage; thus the voltage sine wave across the outer electrodes appears clipped in the figure. (c) The time shift of the peak of the 3rd harmonic current distortion as compared to the peak of the fundamental outer electrode voltage (peaks are near time 0 in (a)) for 3 replicates of ρ+ yeast. As the O2 is consumed, the 3rd harmonic advances with respect to the fundamental. (d) Similar to (c) except the media now contains 10 μM antimycin. The time shift of the antimycin treated ρ+ yeast is similar to the ρ+ yeast in the anaerobic (fermenting) condition in (c).
Mentions: A biological component to the nonlinearity can be seen by comparing the current distortion response from ρ+ and ρ- yeast in oxygen saturated media (Figure 3(a)). The distortion response of the ρ− yeast is advanced relative to the ρ+ strain. As the media was identical in both experiments, the difference must come from the yeast. Furthermore, when the chamber is sealed and the ρ+ yeast are allowed to consume all the oxygen, the ρ+ current distortion advances to the same phase as the ρ− current distortion.

Bottom Line: By simultaneously measuring the bulk media and electrode interface voltages of a yeast (Saccharomyces cerevisiae) suspension subjected to an AC voltage, a yeast-dependent nonlinear response was found only near the current injection electrodes.Computer simulation of yeast near a current injection electrode found an enhanced voltage drop across the yeast near the electrode due to slowed charging of the electrode interfacial capacitance.This voltage drop is sufficient to induce conformation change in membrane proteins.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics and Texas Center for Superconductivity, University of Houston, Houston, TX 77204, USA. apalanisami@uh.edu.

ABSTRACT
By simultaneously measuring the bulk media and electrode interface voltages of a yeast (Saccharomyces cerevisiae) suspension subjected to an AC voltage, a yeast-dependent nonlinear response was found only near the current injection electrodes. Computer simulation of yeast near a current injection electrode found an enhanced voltage drop across the yeast near the electrode due to slowed charging of the electrode interfacial capacitance. This voltage drop is sufficient to induce conformation change in membrane proteins. Disruption of the mitochondrial electron transport chain is found to significantly change the measured nonlinear current response, suggesting nonlinear impedance can be used as a non-invasive probe of cellular metabolic activity.

No MeSH data available.


Related in: MedlinePlus