Exploring metabolic responses of potato tissue induced by electric pulses

In this study, we investigated the metabolic responses of potato tissue induced by pulsed electric field (PEF). Potato tissue was subjected to field strengths ranging from 30 to 500 V/cm, with a single rectangular pulse of 10 μs, 100 μs, or 1 ms. Metabolic responses were monitored using isothermal calorimetry, changes on electrical resistance during the delivery of the pulse, as well as impedance measurements. Our results show that the metabolic response involves oxygen consuming pathways as well as other unidentified events that are shown to be insensitive to metabolic inhibitors such as KCN and sodium azide. The metabolic response is strongly dependent on pulsing conditions and is independent of the total permeabilization achieved by the pulse. Evidence shows that calorimetry is a simple and powerful method for exploring conditions for metabolic stimulation, providing information on metabolic responses that can not be obtained from electrical measurements. This study set the basis for further investigations on defense-related consequences of PEF-induced stress.Sparbanksstiftelsen Färs & Frosta (Sweden).Fundação para a Ciência e a Tecnologia (FCT).Lund University (Sweden).Department of Cell and Organism Biology; Department of Plant Biochemistry

Theoretical fitting of energetics of CAM path to calorimetric data

Moreno, Y. Escuela de Agronomia, Universidad de Talca, Casilla 747 , Talca, Chile.The objective is to test fit of calorimetric data on Crassulacean acid metabolism (CAM) to current concepts in the field. Calculations, done by using maximum observed rates of nocturnal acid accumulation, and ΔH values for reactions in known processes of acid accumulation, were used to predict heat rates. The predicted heat rates were compared with heat rates measured by microcalorimetry. This investigation involved nine diverse species of CAM plants. In six species, calculated and measured values were similar. Fitting the titratable acidity data to the microcalorimetric results, accounts for the expenditure of up to 7.5 molecules ATP per molecule of malate stored in vacuole. Of these 7.5 ATP molecules, fitting suggests 3.5 are derived through the truncated glycolytic path of CAM and up to 4 ATP are generated through the processing of starch through to electron transpor