FIG. 1.

[³⁵S]methionine uptake by total bacterioplankton collected at different depths and by flow cytometrically sorted general bacterial cells (all bact) and Prochlorococcus (Pro). Prochlorococcus was sorted from the replicated fixed samples on two successive days (s.I and s.II). (a) Time series; (b) sorted cell number series. Dashed lines show linear regressions (Regr.), and corresponding regression coefficients (r²) are presented in the keys. DPM, disintegrations per minute.