Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
Volume 68 , Issue 5
Showing 1-12 articles out of 12 articles from the selected issue
  • Hideaki MATSUOKA, Mikako SAITO
    2000 Volume 68 Issue 5 Pages 314-320
    Published: May 05, 2000
    Released: November 10, 2019

    Various types of multifunctional microelectrodes were developed and applied to the signal application to a single target cell and the measurement of its response signal. These signals include chemical, genetic, electric, and electrochemical signals. The signal needs to be applied or detected not only from outside but also from inside of the cell 20-50 µm in diameter. The microelectrode tip diameter was smaller than 1 µm. This size satisfied the experimental requirements that the sticking the electrode into a cell caused no lethal effect. Using a plant bio-cell as well as a model cell, a picoliter water drop, the quantitative injection of an ionic dye, K+, H+, an elicitor, an enzyme and its substrate, and Ca2+ was demonstrated. The quantitative application of an electric signal to a single-cell was also demonstrated. Thus developed methods were basis of the single-cell experiment. Then we analyzed the chitinase gene expression in rice cell and its control with an electric signal. As the result, it was found that the cross membrane potential about 5 mV was enough to trigger the Ca2+ entering the cell. Based on these results, much stress is placed on the single-cell experiment using multifunctional microelectrodes.

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Technical Papers
  • Hiroshi SADAMURA, Satomi KOBAYASHI, Satoshi HONDA, Noriko SUZUKI, Mako ...
    2000 Volume 68 Issue 5 Pages 321-327
    Published: May 05, 2000
    Released: November 10, 2019

    The electrochemical disinfection was carried out using high efficiency electrolytic cell equipped with palladium coated carbon cloth electrodes and low resistance separator where the electrolytic solution passed through parallel to the electrodes. The suspension containing microorganism was flowed through from the symmetric anode compartment to the cathode one, and vise versa. In addition to the efficient disinfection, the secondary pollution due to the electrochemically formed HClO, H+, and OH- was suppressed to minimum. The microorganisms used, Escherichia coli and germinated Bacillus subtilis, were almost perfectly disinfected at very low current, 7 to 10 rnA at a flow rate of 50 cm3 min-1. Even B. subtilis spore was disinfected almost perfectly in the present cell at 200 rnA and 6 V. It was found that the disinfection occurred far effectively in the anode compartment in the chloride containing suspension. According to the direct observation during the disinfection, it was found that the microorganisms were repelled and could not reach the electrode surface in the suspension containing chloride presumably due to the effect of HClO evolved at the anode. The disinfection must occur apart from the electrode surface indirectly due to the evolved HClO. On the other hand, the microorganisms could reach the electrode surface in the low chloride suspension, adsorbed on it, and killed, i.e. the disinfection occurred due to the direct contact as well as HClO in the low chloride circumstance.

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  • Yulia V. BASOVA, Isao TOMIZUKA
    2000 Volume 68 Issue 5 Pages 328-332
    Published: May 05, 2000
    Released: November 10, 2019

    Electrocatalytic properties of potassium tris-dimethylglyoximate Co(III) complex ([Co(Dmg)3] (K)3) and carbonsupported complex materials have been studied by thermogravimetry, infrared spectroscopy, X-ray spectroscopy, mass-spectrometry and cyclic voltammetry technique. It was found that macrobicyclic cobalt(III) complex adsorbed on the surface of carbons based synthetic porous polymers substantially catalyzes the reduction of molecular oxygen. Reduction in the oxygen overpotential was found to occur when catalysts prepared here were heated an in inert atmosphere. The optimum pyrolysis temperature for the most effective catalysts for oxygen reduction was found to be 1073-1123 K.

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  • Mikako SAITO, Yuri KOSAI, Hideaki MATSUOKA
    2000 Volume 68 Issue 5 Pages 333-336
    Published: May 05, 2000
    Released: November 10, 2019

    A pulsing electric signal was applied to a target rice cell with a pair of Pt plate electrodes to modulate the Ca2+ influx into the cells. The change of intracellular concentration of Ca2+ was measured continuously. The cross membrane potential (|VCMP|) generated at the cell membrane was analyzed on the basis of the measured data of potential gradient at the very position of the cell. When |VCMP| was no higher than 1.0 mV, no appreciable influx of Ca2+ was observed. In contrast, when |VCMP| was higher than 1.9 mV, a marked increase in the Ca2+ influx occurred. This influx was inhibited by verapamil, a Ca2+ channel blocker, which suggested the involvement of Ca2+ channel. Therefore, the Ca2+ influx into a rice cell can be modulated with a pulsing electric signal via potential sensitive Ca2+ channels.

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Special Articles
Novel Approaches toward Bioelectrochemical Applications of Genetically Engineered Proteins
Techniques in Electrochemical Measurement