| Abstract: | Cobalt was found to produce effects on cell division, cell protein, volume, calcium uptake, and ultrastructure of the calcifying alga Cricosphaera carterae (Braarud & Fager.) Braarud. The rate of cell division increased slightly as the added Co concentration of the medium was increased from 0–10 μM. At higher added Co concentrations, the rate of division decreased approximately linearly with concentration until division was blocked almost completely at 100 μM Co. Inhibition of division was reversible after 2 days in Co. Protein content was elevated in Co-treated nondividing cells but the rate of protein synthesis was markedly reduced. Cell volume also increased progressively with Co concentration, and after 72 h in 200 μM Co, the volume was 3.2 times that in culture medium (0.09 μM Co). Co had a dual effect on calcification as indicated by the uptake of 45Ca. After 48 h treatment, Ca uptake had increased 53% in 100 μM and decreased 40% in 200 μM Co as compared with cells in 0.09 μM Co. Ultrastructurally, Co caused enlargement of the cell vacuole and the appearance of membrane-bound vacuoles containing electron dense bodies. |
