Table 1.
General cellular, physiological, and biochemical characteristics of Fe-limited P. tricornutum cells and cultures
| Parameter | Fe-limited | Fe-replete | Fe-limited/Fe-replete |
|---|---|---|---|
| Growth rate | 0.18 ± 0.05 | 0.88 ± 0.01 | 0.2 ± 0.06 |
| Ferric reductase assay, AU per cell | 0.717 ± 0.03 | 0.020 ± 0.004 | 35.9 ± 7.3 |
| Ferric reductase assay, AU/μm3 | 0.01 | 0.0002 | 50 |
| Carbon fixation, pmol C per cell × hour | 0.010 ± 0.006 | 0.141 ± 0.022 | 0.07 ± 0.04 |
| Cell diameter, μm | 2.5 | 3.5 | 0.71 |
| Cell volume, μm3 | 60 | 100 | 0.60 |
| Chl per cell, pg per cell | 0.22 | 0.5 | 0.44 |
| Chl per volume, fg/μm3 | 3.67 | 5.0 | 0.73 |
| Fv/Fm | 0.18 ± 0.1 | 0.5 ± 0.05 | 0.36 ± 0.2 |
| PSII | 1.2 ± 0.14 | 1 | 1.2 ± 0.14 |
| PSI | 0.43 ± 0.1 | 1.0 | 0.43 ± 0.10 |
| Cytochrome b6f | 0.75 ± 0.13 | 1.0 | 0.75 ± 0.13 |
| Cytochrome c6 | 0.7 ± 0.05 | 1.0 | 0.70 ± 0.05 |
| NPQ | 4.8 ± 0.8 | 3.1 ± 0.51 | 1.5 ± 0.4 |
| AOX activity | 0.6 ± 0.15 | 0.25 ± 0.18 | 2.4 ± 1.83 |
Photosystem and electron carrier concentrations are given in relative units normalized to Fe-replete levels. AOX activity is given as a percentage of total respiration (see SI Methods for details). Fe levels in Fe-limited and Fe-replete cultures corresponded to 13.4 pmol·liter−1 Fe′ and 2.6 nmol·liter−1 Fe′, respectively.