Heavy metal uptake in relation to phosphorus nutrition in Anabaena variabilis (Cyanophyceae)

Abstract

In one set of experiments cells were starved of phosphorus for 5 days and then exposed to the heavy metals Cd, Cu, Pb and Zn separately at 10 μg g⁻¹. In a separate set of experiments, cells subcultured and grown in complete medium for 5 days were then exposed to the metals using various experimental conditions. An electron probe was then used to determine whether the heavy metal was taken up, and, if so, its location in the cell. In no case was Cd detectable in the cells and no change occurred in the elemental composition of polyphosphate bodies. In all other cases, the metal was taken up by polyphosphate bodies by 18h. In the case of Pb, a strong signal was also obtained in cell wall sectors and a weak signal from cytoplasmic sectors. In cells exposed to Cu, an S peak was also present. The metals Cu, Pb and Zn caused a reduction or loss of the K peak and an increase in the Ca peak in polyphosphate bodies. Differences between metal exposure to phosphorus starved cultures and normal 5-day cultures were determined.