[3] All of the species are small, nonmotile spheres which do not express any distinct morphological features that can be distinguished by either light or electron microscopy.

Nannochloropsis is considered a promising alga for industrial applications because of its ability to accumulate high levels of polyunsaturated fatty acids.

The analysis of the genomes revealed that these microalgae have set of genes for the synthesis and incorporation in the cell wall of cellulose and sulfated fucans and that they are able to store carbon in polymers of β-1,3- and β-1,6-linked glucose called chrysolaminarin.

[14][16] Various orthologs of known blue light sensing proteins were found in the genomes of Nannochloropsis suggesting possible circadian regulation.

The most prominent example of gene dose expansion is Diacylglycerol acyltransferase (DGAT), which catalyzes the last step of triacylglycerol (TAG) synthesis.

Fatty acid biosynthesis in N. oceanica was shown to be integrated with the regulation of the cholesterol biosynthetic pathway, suggesting new genetic engineering or chemical biology approaches for enhanced oil production in microalgae.

It was observed that triacylglycerols largely increase in nitrogen depletion while other lipids, mainly polar glycerolipids, free fatty acids and diacylglycerols, slightly decrease.

[23] Nannochloropsis cultivated in normal growth condition and deprived of a nitrogen source continues growing for 4–5 days.

Transcriptomic data of nitrogen-deprived Nannochloropsis cultures show that various enzymes responsible for degradative processes that release ammonium are indeed up regulated.

[16] All of this data show that genes involved in fatty acid and triacylglycerol biosynthesis are always abundant in the cells and their expression is not correlated with the amount of oil accumulated.

Corteggiani Carpinelli and coworkers (2013)[14] advance the hypothesis that, in their experimental conditions, photosynthesis is the main energy source and the down-regulation of the metabolic activity of the mitochondrion is determinant in increasing the amount of substrates that enter the fatty acid biosynthetic pathway.

Dong et al. (2013)[24] report a quantification of the abundance of various proteins in cultures of Nannochloropsis grown with a supplement of CO2 and deprived of nitrogen.

Despite the different experimental conditions, also the proteomic study seems to support the hypothesis that the accumulation of triacylglycerols is due to an increase of the metabolic flux through the fatty acid biosynthetic pathway.

The authors advance the hypothesis that, in their experimental conditions, the degradation of storage sugars and the up-regulation of glycolysis are responsible for the increase of substrates through the pathway.