INVOLVEMENT OF A CADMIUM-INDUCED LOW-MOLECULAR-WEIGHT PROTEIN IN REGULATING CADMIUM TOXICITY IN THE DIAZOTROPHIC CYANOBACTERIUM ANABAENA-DOLIOLUM

This study demonstrated the production of a cadmium-induced low molecu lar weight (3.5 kDa), buthionine sulfoximine (BSO) sensitive protein i n Anabaena doliolum. Production of this protein was accompanied by a d ecrease in the glutathione level of the cell. Cadmium was found to be differentially toxic to carbon fixation, O-2 evolution, ATP content, n itrate reductase, nitrogenase, alkaline phosphatase and ATPase of cont rol (untreated), BSO, cadmium and (cadmium + BSO) pre-treated A. dolio lum. Toxicity was maximum in BSO-grown cells followed be control (untr eated), cadmium + BSO and least in cadmium-grown A. doliolum. Cadmium and (cadmium + BSO)-grown cells registered an increased lipid producti on, reduced metal uptake and low K+, Na+ loss. In spite of equal cadmi um uptake rates, a significant difference in toxicity between cadmium- grown and (cadmium + BSO)-grown cultures was, however, noticed. Better performance of physiological and biochemical variables of cadmium-gro wn A. doliolum and its tolerance to cadmium could be due to the synthe sis of low molecular weight cadmium binding protein (presumably phytoc helatin) as well as an increased production of lipid.