.DELTA.-4 DESATURASES FROM EUGLENA GRACILIS， EXPRESSING PLANTS， AND OILS CONTAINING PUFA

The invention relates to an improved method for the specific production of unsaturated .omega.-3 fatty acids and a method for producing triglycerides containing an increased number of unsaturated fatty acids， especially .omega.3 fatty acids comprising more than three double bonds. Disclosed is the production of a transgenic organism， preferably a transgenic plant， or a transgenic microorganism containing an increased number of fatty acids， oils， or lipids comprising .DELTA.-4 double bonds as a result of a .DELTA.-4 desaturase being expressed from Euglena gracilis. The invention further relates to expression cassettes containing a nucleic acid sequence， a vector， and organisms containing at least one nucleic acid sequence or an expression cassette. Also disclosed are unsaturated fatty acids and triglycerides having an increased fatty acid content and the use thereof. Fatty acids and triglycerides are used in a plurality of application in the food industry， in animal nutrition， cosmetics， and pharmaceuticals and are suitable for many different applications depending on whether free saturated or unsaturated fatty acids or triglycerides having an increased saturated or unsaturated fatty acid content are used.