A. Glucose uptake vs number of Prochlorococcus PCC 9511 cells (axenic, high irradiance-adapted strain). Radiolabelled glucose, 1 µM final concentration, was added to Prochlorococcus cultures and incubated for 60 min in the light. Cells were sorted to obtain samples containing 5,000, 10,000 and 15,000 cells and glucose uptake was determined. B. Time course of glucose uptake in Prochlorococcus PCC 9511. Radiolabelled glucose, 1 µM final concentration, was added to Prochlorococcus cultures and samples taken at the indicated times and processed as described in Materials and Methods. Bars indicate the average from three independent experiments, each of them determined in triplicate, ±s.d.