FIG 2.

Metabolic activity of subpopulations sorted by NanoSIMS. (A) Flow cytometry scatterplots before and after sorting of three distinct subpopulations (high-, mid-, and low-fl) of an aging Prochlorococcus MIT9313 culture, detected by flow cytometry. The cultures were grown for 30 days in Pro99 and labeled with H¹³CO₃^– and ¹⁵NH₄⁺ for 18 h. (B) NanoSIMS images of ¹⁵N/¹²C analysis of killed cells (negative control) and high-, mid-, and low-fl cells after sorting. (C) Scatterplot of ¹³C/¹²C and ¹⁵N/¹⁴N ratios obtained from NanoSIMS analysis of each subpopulation. (D and E) Boxplots of the ¹³C/¹²C and ¹⁵N/¹⁴N enrichment in each subpopulation. Lines represent the median, X represents the mean, box borders are 1st quartiles, and whiskers represent the full range. Asterisks show significant differences in comparisons between each of the two populations using the Mann-Whitney U test, P < 0.001.