THE ACCUMULATION PROCESS of¹³⁷Cs AND⁹⁰Sr IN THE CELL OF NITELLOPSIS OBTUSA ALGAE

Abstract

Abstract. In the present study, we investigated the accumulation of 137 Cs and 90 Sr in compartments of the Nitellopsis obtusa cells. The effect of Sr 2+ , Cs + and Ca 2+ , K + , which are chemical analogues of 90 Sr and 137 Cs, to the bioelectric parameters of these algae were studied simultaneously. The aim of this work was studying the penetration of 137 Cs and 90 Sr through regulating membrane barriers in the cells of starry stonewort (Nitellopsis obtusa). 137 Cs and 90 Sr are accumulated mainly in the cell membrane (75% to 92%) of these algae. The cell membrane as a cation exchanger regulates ion flow through the first cells diffusion barrier -its thick outer cytomembrane (the complex consisting of the cell wall and plasmalemma). Significantly, smaller amounts of 137 Cs and 90 Sr enter into the cytoplasm than in the cytomembrane, 10-20% and 3-10%, respectively. Analysis of the accumulation levels of 137 Cs and 90 Sr in the compartments of the Nitellopsis obtusa cells show their accumulation in the cell membrane as well as their active transport through outer and inner cytoplasmic membranes. Membrane potentials determined mainly by the gradient of the K + ions are doing an important regulatory function in this process. From the obtained data it results that cells of Nitellopsis obtusa algae can be a convenient radioecological model for the study of the accumulation of radionuclides in plants at the cellular level.