The nitrogen costs of photosynthesis in a diatom under current and future pCO2

• Main Authors: Li, Gang, Brown, Christopher M, Jeans, Jennifer A, Donaher, Natalie A, McCarthy, Avery, Campbell, Douglas A
• Format: Dataset
• Language: English
• Published: PANGAEA 2015
• Subjects: Alkalinity; total; Aragonite saturation state; Bicarbonate ion; Biomass/Abundance/Elemental composition; Bottles or small containers/Aquaria (<20 L); Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cell biovolume; Chlorophyll a per cell; Chlorophyll c per cell; Chromista; Cytochrome c1; Fucoxanthin chlorophyll protein per cell; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Identification; Irradiance; Laboratory experiment; Laboratory strains; Light; Nitrogen content per cell; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Ochrophyta; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphate; Photosynthetic protein; PsbC; Photosynthetic protein PsbA; Photosynthetic protein PsbD; Photosynthetic protein Rubisco; Phytoplankton; Potentiometric; Primary production/Photosynthesis; Protein per cell; Ratio; Salinity; Silicate; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.847792; https://doi.org/10.1594/PANGAEA.847792

With each cellular generation, oxygenic photoautotrophs must accumulate abundant protein complexes that mediate light capture, photosynthetic electron transport and carbon fixation. In addition to this net synthesis, oxygenic photoautotrophs must counter the light-dependent photoinactivation of Photosystem II (PSII), using metabolically expensive proteolysis, disassembly, resynthesis and re-assembly of protein subunits. We used growth rates, elemental analyses and protein quantitations to estimate the nitrogen (N) metabolism costs to both accumulate the photosynthetic system and to maintain PSII function in the diatom Thalassiosira pseudonana, growing at two pCO2 levels across a range of light levels. The photosynthetic system contains c. 15-25% of total cellular N. Under low growth light, N (re)cycling through PSII repair is only c. 1% of the cellular N assimilation rate. As growth light increases to inhibitory levels, N metabolite cycling through PSII repair increases to c. 14% of the cellular N assimilation rate. Cells growing under the assumed future 750 ppmv pCO2 show higher growth rates under optimal light, coinciding with a lowered N metabolic cost to maintain photosynthesis, but then suffer greater photoinhibition of growth under excess light, coincident with rising costs to maintain photosynthesis. We predict this quantitative trait response to light will vary across taxa.