No abstract

The effect of anoxia on the energy economy of root cells was studied by measuring heat production, ethanol and ATP production, K(+) fluxes and electrical activity in two Vitis species, V. riparia and V. rupestris, that differ in their tolerance to anoxia. Anoxia triggered a marked decrease of metabolic activity (measured by microcalorimetry) and of ATP levels in both species. In V. riparia after the first 2 h of anoxia, the decrease in the rate of heat production was not associated with a further significant decrease in ATP content, whereas in V. rupestris the ATP level continued to decrease until very low values were reached. The concomitant increase in the rate of ethanol production did not compensate for the decreased aerobic ATP supply. In V. rupestris, anoxia typically led to energy deficit and ATP imbalance, together with the subsequent disruption of ion homeostasis and cell death. In V. riparia, the strong decrease in K(+) membrane permeability together with the fast down-regulation of the electrical signals allowed the cells to avoid severe ion imbalances during prolonged anoxic episodes.

1 Hz rTMS over the supplementary motor area appeared to be effective in approximately 2/3 of SSRI-refractory OCD subjects, whereas in the TAU group only 1/4 of subjects were responders. The supplementary motor area might be a new target area to be further explored with neuromodulation for OCD treatment.

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.