Fig. 5: Schematic of cell flux model simulating heterogeneity of Crocosphaera during the dark period. | Communications Biology

Fig. 5: Schematic of cell flux model simulating heterogeneity of Crocosphaera during the dark period.

From: Heterogeneous nitrogen fixation rates confer energetic advantage and expanded ecological niche of unicellular diazotroph populations

Fig. 5

Green space, cytoplasmic space; peach frames, cell membrane layers; circular blobs, chemical compounds; solid arrows, material fluxes; dashed arrows, energy fluxes. C store represents C storage accumulated during the preceding light period, which is used for multiple purposes. The use of C store is represented by solid arrows of different colors by C fluxes and the different energy fluxes from respiration are colored differently; see the list at the bottom. fN represents the fraction of N2 fixing cells; thus that of non-nitrogen-fixing cells becomes 1 − fN. The O2 concentration of N2 fixing cell \([{{{\mathrm{O}}}}_2^{}]_C^N\) is kept small through respiratory protection at the expense of C store. Contrarily, only biosynthetic respiration occurs in non- N2 fixing cells. Excreted, fixed N\(\left( {{{{\mathrm{NH}}}}_4^ + } \right)\) is transferred to non-N2-fixing cells with efficiency of EN; 1 − EN is the fraction of excreted NH4+ lost to the environment. Cells grow at the rate of μ (d−1).

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