Binding of radioisotopes of cesium with P. sp binos. a

, 10, 30, and 100 mg/ml of wet algal cells were incubated with 1.92 kBq of ¹³⁷CsCl at room temperature for 10 min. Radioactivity accumulated in algal cells were measured, and data are shown as % of total radioactivity (mean ± SD). *, P<0.05, **, P<0.01 (n = 4). b, After 10 min incubation, the radioactivities of pellets and supernatant were measured and the bound/free ratios were calculated (n = 4). c, Ten mg/ml of wet algal cells were incubated with nonradioactive CsCl (solid circles) or NaCl (open circles) and 1.92 kBq of ¹³⁷CsCl at room temperature for 10 min. Radioactivity accumulated in algal cells were measured, and data are shown as % of control uptake without nonradioactive CsCl. Non-linear curve fitting to the model of two binding sites with high and low affinities was performed using the CsCl and NaCl competition data (n = 4).