Anionic Transport in Nitella clavata

Abstract

This study examines aspects of anion transport, focusing on Cl-, No_3- and So_4-2 in Nitella clavata. The researcher measures the uptake of radioactive Cl- in the presence/absence of a hexose in order to determine if glucose inhibits Cl- influx. The author grew Nitella clavata in open tanks of culture solution, with a light intensity of 100 foot-candles at the cultures’ surface. Only the first, second, or third intermodal cells proximal to the apical tip were used. Harvested cells were then conditioned from one to seven days under controlled conditions. First, the researcher used titration to measure net hydrogen ion influxes and hydroxide effluxes. Then the researcher treated cells in with K/experimental solutions and rinsed them in non-tracer/appropriate experimental solution in order to measure cell radioactivity. The researcher also measured unidirectional chloride efflux using a radioassay with a Nuclear-Chicago low background gas flow counter. Intracellular chloride activity was determined by measuring vacuolar sap chloride concentration potentiometrically. Ultimately, the researcher could find no evidence to support the hypothesis that Nitella clavata possesses a hexose/H+ cotransport system, nor could she provide evidence for a Cl-/H+ cotransport system through competitive inhibition with a hexose/H+ mechanism. Possibilities for further research include radioisotope tracing of NO_3-, Cl- and SO_4-2 in the presence of other anions.