Phytoplankton can be exposed to periods of N starvation with episodic N resupply. N starvation in
Dunaliella tertiolecta (Butcher) measured over 4 days was characterized by slow reduction in cell chl and protein content and chl/carotenoid ratio and a decline in photosynthetic capacity and maximum quantum yield of photosynthesis (F
v/F
m). In the early stages of N starvation, cell division was maintained despite reduction in cellular chl. Chl content was more sensitive than carotenoids to N deprivation, and cellular chl
a was maintained preferentially over chl
b under N starvation. NO
3? resupply stimulated rapid and complete recovery of F
v/F
m (from 0.4 to 0.7) within 24 h and commencement of cell division after 10 h, although N‐replete levels of cell chl and protein were not reestablished within 24 h. Recovery of F
v/F
m was correlated with increases in cell chl and protein and was more related to increases in F
m than to changes in F
0. Recovery of F
v/F
m was biphasic with a second phase of recovery commencing 4–6 h after resupply of NO
3?. Uptake of NO
3? from the external medium and the recovery of F
v/F
m, cell chl, and protein were inhibited when either cytosolic or chloroplastic protein synthesis was inhibited by cycloheximide or lincomycin, respectively; a time lag observed before maximum NO
3? uptake was consistent with synthesis of NO
3? transporters and assimilation enzymes. When both chloroplastic and cytosolic translation was inhibited, F
v/F
m declined dramatically.
Dunaliella tertiolecta demonstrated a capacity to rapidly reestablish photosynthetic function and initiate cell division after N resupply, an important strategy in competing for limiting inorganic N resources.
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