A polarographic, oxygen-selective, vibrating-microelectrode system for the spatial and temporal characterisation of transmembrane oxygen fluxes in plants

Abstract

A simple procedure is described for the fabrication of micrometer to nanometer-scale platinum electrodes to be used in a vibrating oxygen-selective system. The electrode was prepared by etching a fine platinum wire and insulating it with an electrophoretic paint. The dimensions allowed this electrode to be used with the "vibrating probe technique" in exploratory studies aimed at mapping and measuring the patterns of net influxes as well as effluxes of oxygen in Olea europaea L. leaves and roots with spatial and temporal resolutions of a few microns and a few seconds, respectively. The magnitude and spatial localisation of O2 influxes in roots was characterised by two distinct peaks. The first, in the division zone, averaged 38 +/- 5 nmol m(-2) s(-1); the second, in the elongation region, averaged 68 +/- 6 nmol m(-2) s(-1). Long-term records of oxygen influx in the elongation region of the root showed an oscillatory regime characterised by a fast oscillation with periods of about 8-9 min. In leaves, the system allowed the measurement of real-time changes in O2 evolution following changes in light. Furthermore, it was possible to obtain "topographical" images of the photosynthetically generated oxygen diffusing through different stomata from a region of the leaf of 120 microm x 120 microm. The combination of topographic and electrochemical information at the micrometer scale makes the system an efficient tool for studying biological phenomena involving oxygen diffusion.

Spatiotemporal dynamics of the electrical network activity in the root apex

“…Interestingly, oscillations in membrane activity are almost exclusively detected in the root apex, which is also the region of the greatest electrical activity and synchronization (Fig. 7), and only rarely in the basal root zones (61)(62)(63).…”

Self-referencing optrodes for measuring spatially resolved, real-time metabolic oxygen flux in plant systems

“…SR polarographic sensors have been used to measure respiratory oxygen flux for single cells of mouse embryos and oocytes (Porterfield et al 1998), cultured Aplysia neurons (Land et al 1999), Spirogyra grevilleana (Land et al 1999;, pancreatic b cells , Olea europaea leaves and roots (Mancuso et al 2000), Vitis roots (Mancoso and Boselli 2002), and cancer tumor spheroids ).…”

Enhancement of ammonium and potassium root influxes by the application of marine bioactive substances positively affects Vitis vinifera plant growth

“…A detailed description of the technique is provided by Shabala et al (2006) and Mancuso et al (2000) or in the review by Mugnai et al (2006). Briefly, Vitis vinifera healthy root apices (5-6 mm long) were cut, carefully washed with deionized water and placed one at a time at the bottom of the measuring chamber containing a nutrient solution (NH 4 + , 5 ppm; K + , 153 ppm) and a MBS (0.1%).…”