The present invention relates to a polynucleotide from Emiliana huxleyi which codes for a desaturase and which can be employed for the recombinant production of polyun- saturated fatty acids. The invention furthermore relates to vectors, host cells and transgenic nonhuman organisms which comprise the polynucleotide according to the invention, and to the polypeptides encoded by the polynucleotide. The invention furthermore relates to antibodies against the polypeptide according to the invention. Finally, the invention also relates to production methods for the polyunsaturated fatty acids and for oil, lipid and fatty acid compositions and to their use as drugs, cosmetics, foodstuffs, feedstuffs, preferably fish food, or food supplements.
