| Abstract: | Phormidium luridum cultures were treated with sodium selenite in concentrations ranging from 10?6 M to 10?2 M. In contrast to the increasing culture turbidity of control and 10?6 M selenite cultures, the turbidity of the other selenite cultures declined in proportion to time and selenite concentration. Chlorophyll extraction revealed similar results. Photosynthetic activity was inhibited within 6 hr in all cultures except control and 10?6 M selenite. Phormidium at concentrations greater than 10?6 M selenite showed a gradual loss of the bright green color and turned semitransparent. Cell-associated granules of reduced selenium were observed at higher selenite concentrations. Other structural changes observed were the presence of intracellular and intercellular spaces, spheroplast formation, and gradual cell lysis. Protein analyses of total cell samples and supernatant fractions confirmed cellular breakdown of selenite-treated algal cells. |
