A primary physiological response to nitrogen limitation is a decrease in cell growth, as observed with the three times reduction in N. oleoabun­dans growth rate. The transcript profile of nitrogen-starved N. oleoabundans clearly reflects the decrease in cell proliferation and stressed physiological status of the cells. Gene ontology terms related to cellular growth, photo­synthesis, and protein machinery are significantly suppressed under — N conditions, and autophagy genes were up-regulated. The 5’ AMP-activat­ed protein kinase (SnRKl gene in plants) was slightly overexpressed in the — N scenario. SnRKl is activated under starvation conditions, includ­ing nitrogen depletion [31] and is a global regulator of starch and TAGs production in plants [30]. Overexpression of SnRKl in the transgenic po­tato Solanum tubersum cv. Prairie [35] and Arabidopsis thaliana[36] has resulted in changes in starch and carbohydrate levels, thus confirming this gene’s central role in carbon partitioning and suggesting that SnRKl may be an important target for metabolic engineering efforts in oleaginous mi­croalgae. We note also that genes encoding for the components of nitrogen assimilation are identified as the most significantly up-regulated genes in the transcriptome of nitrogen limited N. oleoabundans. Overexpression of nitrogen assimilation pathways under nitrogen limiting conditions has been previously reported in the transcriptome of other non-oleaginous mi­croalgae species [10,33].