Proteome response of the diatom Phaeodactylum tricornutum to short term shifts in nitrogen source and availability.

The photosynthetic model marine diatom Phaeodactylum tricornutum was cultured with varying nitrogen sources and availability to elicit shifts in the proteome. Cells were grown to mid-exponential phase on ammonium (880 uM), collected by centrifugation and resuspended in N-free media for 2 hrs, and spiked with nitrate (150 uM) for 90 min. Cells were again collected by centrifugation, washed in N-free media, and resuspended in experimental treatments with no nitrogen (N-) and a nitrogen source (300 uM) provided as ammonium, nitrite, or nitrate. Each experimental treatment was sampled after 15 min, 45 min, and 18 hr.