EFFECT OF CALCIUM, ITS INHIBITORS, AND HEAVY-METALS ON THE GROWTH-CYCLE OF PEANUT CELL AGGREGATES

During the normal growth cycle of peanut (Arachis hypogaea L.) cells, cultured in suspension medium, cell aggregates of <0.5 mm were formed during the log phase and grew to aggregates of >0.5 mm during late growth phase. Calmodulin rose to its original level during <0.5 mm aggregate formation following an initial 50% drop. Observations by UV microscopy showed that calmodulin. Ca2+ was centered in intense fluorescent sites. Calmodulin antagonists and a calcium chelator inhibited <0.5 mm aggregate formation as well as protein accumulation. The chelator suppressed cationic peroxidase isozyme release, while the antagonists had some partial effect on the anionic isozyme. Some heavy metals such as cadmium, mercury, lead and cobalt at low concentrations would allow continued growth of >0.5 but not of the <0.5 populations. At high (1 mM) concentrations these ions caused arrested growth. At low (10 muM) levels and in the presence of 3 mM calcium they had a synergistic effect.