Potentiometric sensor for the measurement of Cd2+ transport in yeast and plants

Research on heavy metals, and especially on transport of Cd2+, has attracted much interest during the past decade. An optimized Cd2+-selective electrode for the continuous potentiometric monitoring of Cd2+ fluxes in biological systems is presented. The selectivity of the electrode for Cd2+ was further improved, and it now has very good long-term stability. The utility of this simple and inexpensive method is demonstrated by studying the Cd2+ transport with model organisms, such as the yeast Saccharomyces cerevisiae and Arabidopsis cell cultures, frequently used in plant science. Its lower detection limits in the presence of commonly used growth media for yeast and plant cells are improved by approximately three orders of magnitude and are 10−10 and 10−8 M Cd2+, respectively. Control experiments using atomic absorption spectrophotometry confirm that the decrease in Cd2+ activities in the cell cultures is indeed due to the uptake of these metal ions by the cells. Both model systems can be easily transformed; therefore, in combination with the new electrode, they are very promising tools for the investigation of any protein of interest that might be involved in Cd2+ transport.