Frequency-dependent membrane impedance inChara corallina estimated by Fourier analysis

Ross, Stephen M.; Ferrier, Jack; Dainty, J.

doi:10.1007/bf01871518

Cited by 16 publications

(12 citation statements)

References 23 publications

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“…This means that the voltage noise PSD sampled from the cell after treatment with DCCD (Fig. 2a) will be larger relative to the control PSD than if correction had been made for membrane impedance as described in (20)(21)(22), but it is still clear that DCCD strongly inhibited the LFSC. These results, along with the studies quoted above (2, 6, 7), imply that DCCD inhibits the active proton pump directly.…”

Section: Discussionmentioning

confidence: 97%

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Membrane Electrical Noise in Chara corallina

Ross

Dainty²

1986

Plant Physiol.

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Certain inhibitors have been found to affect the low frequency spectral component of the electrical noise power spectrum in Chara corallina. Application of the ATPase inhibitor N,N'-dicyclohexylcarbodiimide removed the low frequency spectral component, strengthening the case that the component is produced by active proton pumping. Cytocholasin B, which inhibits cyclosis in internodes of C. corallina, removed the low frequency spectral component in a time-dependent fashion which was correlated with the cessation of streaming. The protonophore carbonyl cyanide m-chlorophenylhydrazone did not produce consistent effects on the low frequency spectral component in these cells.In noise analysis, the power spectral density resulting from a signal which is the sum of two or more statistically independent noise generating processes is equal to the sum of the PSDs3 of each of those processes individually. This implies that in membrane noise analysis, inhibition of an electrical noise-producing transport process will remove the portion ofthe power spectrum produced by that particular ion flux. Inhibitors with known properties may therefore be used to study the type of transport process which is responsible for specific spectral characteristics in the noise PSD from a given cell type.In a previous paper (21) we described a low frequency spectral component which appeared to be produced by active proton transport in internodes of Chara corallina at pH values from 5.2 to 9 in the light. We have investigated the nature of this spectral component using various inhibitory compounds, to see whether the identification of the LFSC with active proton transport could be further confirmed or refuted, and to study the interaction between cyclosis and membrane transport in these cells. MATERIALS AND METHODSThe experimental arrangement for sampling voltage noise signals from internodes of Chara corallina has been described previously (21,22 described by Hope and Walker (4), which will henceforth be referred to as CPW. The CPW was supplemented with the inhibitors listed in Table I. The voltage noise signals were analogto-digital converted and stored on a PDP-1 1/03 computer system, and power spectra computed by means of the fast Fourier transform technique (20,21). In all cases spectra were sampled with the cells under control conditions in CPW, illuminated by a halogen lamp at 30 W/m2, then compared to spectra sampled in the presence of an inhibitor.The inhibitors were not very water soluble, and had to be dissolved either in ethanol or DMSO to make a concentrated stock solution, which was added to the CPW to obtain the desired final concentration ofinhibitor as indicated in Table I. The stock solutions of inhibitors were stored in a freezer at -1 1°C between experiments and were mixed with the CPW just prior to use in an experiment. Table I also indicates the final v/v concentration of organic solvent included in the media. Control experiments in which 0.25% v/v ethanol was added to the CPW did not result in any change in transmem...

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Section: Discussionmentioning

confidence: 97%

“…The experimental arrangement for sampling voltage noise signals from internodes of Chara corallina has been described previously (21,22 described by Hope and Walker (4), which will henceforth be referred to as CPW. The CPW was supplemented with the inhibitors listed in Table I.…”

Section: Methodsmentioning

confidence: 99%

Membrane Electrical Noise in Chara corallina

Ross

Dainty²

1986

Plant Physiol.

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“…Cells were cultured in the laboratory in fiberglass tanks as described previously ( 19). Figure 1 illustrates schematically the experimental arrangement used to sample voltage noise signals.…”

Section: Methodsmentioning

confidence: 99%

“…The CPW was buffered by adding 5 mm Tes and titrating to pH 7.5 with 1 M NaOH. Other pH values were obtained using 5 mm concentrations of the buffers described in Ross et al (19).…”

Section: Methodsmentioning

confidence: 99%

Membrane Electrical Noise in Chara corallina

Ross

Dainty²

1985

Plant Physiol.

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Some aspects of the membrane physiology of the giant-celled alga Chara corallina have been studied using the techniques of membrane noise analysis. Cellular voltage noise was measured by means of a microelectrode inserted in the vacuole of the cell. The significant feature of spectra estimated from voltage noise signals in these cells was a lowfrequency component possibly associated with the active, electrogenic proton pumping which occurs in these cells. The effect of high external pH is described.

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“…It has been observed in samples as different as crystalline and amorphous semiconductor devices, [1][2][3][4][5][6][7][8][9] organic compounds, [10][11][12][13][14] composite materials/nanomaterials, 9,15-22 electrochemical cells, [23][24][25] geological samples, 26 biological membranes, [27][28][29] and even moist surfaces. 30 Furthermore, it has been shown that NCs can originate at interfaces as well as in the bulk of the materials.…”

Section: Introductionmentioning

confidence: 99%

General mechanism for negative capacitance phenomena

et al. 2009

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The existence of a negative static dielectric constant has drawn a great deal of theoretical controversy. Experimentally, one has never been observed. However, low-frequency negative capacitance has been widely reported in fields including physics, chemistry, biology, geology, and electronics. This wide variety of systems possesses an extremely diverse set of physical processes that, surprisingly, share similar characteristics. We present a general mechanism that unites the various instances of negative capacitance under a common framework. The mechanism demonstrates that the negative capacitance arises from dc/ac signal mixing across a nonlinear conductor. Verification of the model is performed in physically distinct samples: an electrorheological fluid, a fuel cell, and a solar cell. Furthermore, we argue that the negative capacitance, under appropriate conditions, can be associated with a negative-differential dielectric constant, possibly even in the static limit.

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Frequency-dependent membrane impedance inChara corallina estimated by Fourier analysis

Cited by 16 publications

References 23 publications

Membrane Electrical Noise in Chara corallina

Membrane Electrical Noise in Chara corallina

Membrane Electrical Noise in Chara corallina

General mechanism for negative capacitance phenomena

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