Patent Publication Number: US-8993841-B2

Title: Fatty acid elongation components and uses thereof

Description:
RELATED APPLICATIONS 
     This application is a national stage application (under 35 U.S.C. §371) of PCT/EP2010/056936, filed May 20, 2010 which claims benefit of European Application No. 09162204.3 filed Jun. 8, 2009. 
     SUBMISSION OF SEQUENCE LISTING 
     The Sequence Listing associated with this application is filed in electronic format via EFS-Web and hereby incorporated by reference into the specification in its entirety. The name of the text file containing the Sequence Listing is Sequence_Listing_17418  — 00078 U.S. The size of the text file is 72 KB and the text file was created on Dec. 5, 2011. 
     The invention in principle pertains to the field of recombinant manufacture of fatty acids. It provides nucleic acid molecules which encode novel fatty acid dehydratase/enoyl-CoA reductase (nECR) family members. The invention also provides recombinant expression vectors containing nECR nucleic acid molecules, host cells into which the expression vectors have been introduced, and methods for large-scale production of long chain polyunsaturated fatty acids (LCPUFAs), e.g. ARA, EPA and DHA. 
     Fatty acids are carboxylic acids with long-chain hydrocarbon side groups that play a fundamental role in many biological processes. Fatty acids are rarely found free in nature but, rather, occur in esterified form as the major component of lipids. As such, lipids/fatty acids are sources of energy (e.g., b-oxidation). In addition, lipids/fatty acids are an integral part of cell membranes and, therefore, are indispensable for processing biological or biochemical information. 
     Fatty acids can be divided into two groups: saturated fatty acids formed of single carbon bonds and the unsaturated fatty acids which contain one or more carbon double bonds in cis-configuration. Unsaturated fatty acids are produced by terminal desaturases that belong to the class of nonheme-iron enzymes. Each of these enzymes are part of an electron-transport system that contains two other proteins, namely cytochrome b 5  and NADH-cytochrome b 5  reductase. Specifically, such enzymes catalyze the formation of double bonds between the carbon atoms of a fatty acid molecule, for example, by catalyzing the oxygen-dependent dehydrogenation of fatty acids (Sperling et at., 2003). Human and other mammals have a limited spectrum of desaturases that are required for the formation of particular double bonds in unsaturated fatty acids and thus, have a limited capacity for synthesizing essential fatty acids, e.g., long chain polyunsaturated fatty acids (LCPUFAs). Thus, humans have to take up some fatty acids through their diet. Such essential fatty acids include, for example, linoleic acid (C18:2), linolenic acid (C18:3). In contrast, insects, microorganisms and plants are able to synthesize a much larger variety of unsaturated fatty acids and their derivatives. Indeed, the biosynthesis of fatty acids is a major activity of plants and microorganisms. 
     Long chain polyunsaturated fatty acids (LCPUFAs) such as docosahexaenoic acid (DHA, 22:6(4,7,10,13,16,19)) are essential components of cell membranes of various tissues and organelles in mammals (nerve, retina, brain and immune cells). For example, over 30% of fatty acids in brain phospholipid are 22:6 (n-3) and 20:4 (n-6) (Crawford, M. A., et al, (1997) Am. J. Clin. Nutr. 66:1032S-1041S). In retina, DHA accounts for more than 60% of the total fatty acids in the rod outer segment, the photosensitive part of the photoreceptor cell (Giusto, N. M., et al. (2000) Prog. Lipid Res. 39:315-391). Clinical studies have shown that DHA is essential for the growth and development of the brain in infants, and for maintenance of normal brain function in adults (Martinetz, M. (1992) J. Pediatr. 120: S129-S138). DHA also has significant effects on photoreceptor function involved in the signal transduction process, rhodopsin activation, and rod and cone development (Giusto, N. M., et al. (2000) Prog. Lipid Res. 39:315-391). In addition, some positive effects of DHA were also found on diseases such as hypertension, arthritis, atherosclerosis, depression, thrombosis and cancers (Horrocks, L. A. and Yeo, Y. K. (1999) Pharmacol. Res. 40:211-215). Therefore, appropriate dietary supply of the fatty acid is important for human health. Because such fatty acids cannot be efficiently synthesized by infants, young children and senior citizens, it is particularly important for these individuals to adequately intake these fatty acids from the diet (Spector, A. A. (1999) Lipids 34:S1-S3). 
     Currently the major sources of DHA are oils from fish and algae. Fish oil is a major and traditional source for this fatty acid, however, it is usually oxidized by the time it is sold. In addition, the supply of fish oil is highly variable, particularly in view of the shrinking fish populations. Moreover, the algal source of oil is expensive due to low yield and the high costs of extraction. 
     EPA and ARA are both essential fatty acids. They form a unique class of food and feed constituents for humans and animals. EPA belongs to the n-3 series with five double bonds in the acyl chain. EPA is found in marine food and is abundant in oily fish from North Atlantic. ARA belongs to the n-6 series with four double bonds. The lack of a double bond in the ω-3 position confers on ARA different properties than those found in EPA. The eicosanoids produced from AA have strong inflammatory and platelet aggregating properties, whereas those derived from EPA have anti-inflammatory and anti-platelet aggregating properties. ARA can be obtained from some foods such as meat, fish and eggs, but the concentration is low. 
     Gamma-linolenic acid (GLA) is another essential fatty acid found in mammals. GLA is the metabolic intermediate for very long chain n-6 fatty acids and for various active molecules. In mammals, formation of long chain polyunsaturated fatty acids is rate-limited by Δ6 desaturation. Many physiological and pathological conditions such as aging, stress, diabetes, eczema, and some infections have been shown to depress the Δ6 desaturation step. In addition, GLA is readily catabolized from the oxidation and rapid cell division associated with certain disorders, e.g., cancer or inflammation. Therefore, dietary supplementation with GLA can reduce the risks of these disorders. Clinical studies have shown that dietary supplementation with GLA is effective in treating some pathological conditions such as atopic eczema, premenstrual syndrome, diabetes, hypercholesterolemia, and inflammatory and cardiovascular disorders. 
     Although biotechnology offers an attractive route for the production of specialty fatty acids, current techniques fail to provide an efficient means for the large scale production of unsaturated fatty acids. Accordingly, there exists a need for an improved and efficient method of producing unsaturated fatty acids, such as DHA, EPA and ARA. 
     Thus, the present invention relates to a polynucleotide comprising a nucleic acid sequence elected from the group consisting of:
         a) a nucleic acid sequence having a nucleotide sequence as shown in SEQ ID NOs: 1 or 3;   b) a nucleic acid sequence encoding a polypeptide having an amino acid sequence as shown in SEQ ID NOs: 2 or 4;   c) a nucleic acid sequence being at least 50% identical to the nucleic acid sequence of a) or b), wherein said nucleic acid sequence encodes a polypeptide having dehydratase/enoyl-CoA reductase (nECR) activity;   d) a nucleic acid sequence encoding a polypeptide having nECR activity and having an amino acid sequence which is at least 50% identical to the amino acid sequence of any one of a) to c); and   e) a nucleic acid sequence which is capable of hybridizing under stringent conditions to any one of a) to d), wherein said nucleic acid sequence encodes a polypeptide having nECR activity.       

     The term “polynucleotide” as used in accordance with the present invention relates to a polynucleotide comprising a nucleic acid sequence which encodes a polypeptide having dehydratase/enoyl-CoA reductase (nECR) activity. Preferably, the polypeptide encoded by the polynucleotide of the present invention having nECR activity upon expression in a plant shall be capable of increasing the amount of PUFA and, in particular, LCPUFA in, e.g., seed oils or the entire plant or parts thereof. Such an increase is, preferably, statistically significant when compared to a LCPUFA producing transgenic control plant which expresses the minimal set of desaturases and elongases required for LCPUFA synthesis but does not express the polynucleotide of the present invention. Whether an increase is significant can be determined by statistical tests well known in the art including, e.g., Student&#39;s t-test. More preferably, the increase is an increase of the amount of triglycerides containing LCPUFA of at least 5%, at least 10%, at least 15%, at least 20% or at least 30% compared to said control. Preferably, the LCPUFA referred to before is a polyunsaturated fatty acid having a C-20, C-22 or C24 fatty acid body, more preferably, ARA, EPA or DHA. Suitable assays for measuring the activities mentioned before are described in the accompanying Examples. 
     The term “nECR activity” or “dehydratase/enoyl-CoA reductase activity” as used herein refers to the combined activity of a enoyl-CoA reductase and a dehydratase, i.e. the enzyme having the combined activity shall be capable of removing a hydroxyl group from 3-hydroxy-acyl-CoA and reducing the formed double bond as part of the elongation process for fatty acids. Fatty acid elongation is catalyzed in four steps, represented by four enzymes: KCS (keto-acyl-CoA-synthase), KCR (keto-acyl-CoA-reductase), DH (dehydratase) and ECR (enoyl-CoA-reductase). In the first step a fatty acid-CoA ester is condensed with malonyl-CoA producing a keto-acly-CoA intermediate, which is elongated by two carbon atoms, and CO 2 . The keto-group of the intermediate is then reduced by the KCR to a hydroxyl-group. In the next step the DH cleaves of the hydroxyl-group (H 2 O is produced), forming a acyl-2-en-CoA ester (delta-2-enoyl-CoA). In the final step the double bound at position 2, 3 is reduced by the ECR forming the elongated acyl-CoA ester (Buchanan, Gruissem, Jones (2000) Biochemistry &amp; Molecular biology of plants, American Society of Plant Physiologists). In the studies underlying this invention, a natural occurring fusion of DH and ECR with superior catalytic activities and specificities towards LCPUFA has been provided. 
     More preferably, polynucleotides having a nucleic acid sequence as shown in SEQ ID NOs: 1 or 3 encoding polypeptides having amino acid sequences as shown in SEQ ID NOs: 2 or 4 or variants thereof, preferably, exhibit nECR activity. 
     A polynucleotide encoding a polypeptide having a nECR activity as specified above has been obtained in accordance with the present invention, preferably, from  Thalassiosira pseudonana  or  Phaeodactylum tricornutum . However, orthologs, paralogs or other homologs may be identified from other species. Preferably, they are obtained from plants such as algae, for example  Isochrysis, Mantoniella, Ostreococcus  or  Crypthecodinium , algae/diatoms such as  Phaeodactylum, Thalassiosira  or  Thraustochytrium , mosses such as  Physcomitrella  or  Ceratodon , or higher plants such as the Primulaceae such as  Aleuritia, Calendula stellata, Osteospermum spinescens  or  Osteospermum hyoseroides , microorganisms such as fungi, such as  Aspergillus, Phytophthora, Entomophthora, Mucor  or  Mortierella , bacteria such as  Shewanella , yeasts or animals. Preferred animals are nematodes such as  Caenorhabditis , insects or vertebrates. Among the vertebrates, the nucleic acid molecules may, preferably, be derived from Euteleostomi, Actinopterygii; Neopterygii; Teleostei; Euteleostei, Protacanthopterygii, Salmoniformes; Salmonidae or Oncorhynchus, more preferably, from the order of the Salmoniformes, most preferably, the family of the Salmonidae, such as the genus  Salmo , for example from the genera and species  Oncorhynchus mykiss, Trutta trutta  or  Salmo trutta fario . Moreover, the nucleic acid molecules may be obtained from the diatoms such as the genera  Thallasiosira  or  Phaeodactylum.    
     Thus, the term “polynucleotide ” as used in accordance with the present invention further encompasses variants of the aforementioned specific polynucleotides representing orthologs, paralogs or other homologs of the polynucleotide of the present invention. Moreover, variants of the polynucleotide of the present invention also include artificially generated muteins, Said muteins include, e.g., enzymes which are generated by mutagenesis techniques and which exhibit improved or altered substrate specificity, or codon optimized polynucleotides. The polynucleotide variants, preferably, comprise a nucleic acid sequence characterized in that the sequence can be derived from the aforementioned specific nucleic acid sequences shown in any one of SEQ ID NOs: 1 or 3 or by a polynucleotide encoding a polypeptide having an amino acid sequence as shown in any one of SEQ ID NOs: 2 or 4 by at least one nucleotide substitution, addition and/or deletion, whereby the variant nucleic acid sequence shall still encode a polypeptide having a nECR activity as specified above. Variants also encompass polynucleotides comprising a nucleic acid sequence Which is capable of hybridizing to the aforementioned specific nucleic acid sequences, preferably, under stringent hybridization conditions. These stringent conditions are known to the skilled worker and can be found in Current Protocols in Molecular Biology, John Wiley &amp; Sons, N. Y. (1989), 6,3 ,1-6.3,6, A preferred example for stringent hybridization conditions are hybridization conditions in  6  x sodium chloride/sodium citrate (=SSC) at approximately 45° C., followed by one or more wash steps in 0.2 ×SSC, 0 ,1% SDS at 50 to 65° C. The skilled worker knows that. these hybridization conditions differ depending on the type of nucleic acid and, for example when organic solvents are present, with regard to the temperature and concentration of the buffer. For example, under “standard hybridization conditions” the temperature differs depending on the type of nucleic acid between 42° C. and 58° C. in aqueous buffer with a concentration of 0.1 to 5 ×SSC (pH 7.2), If organic solvent is present in the abovementioned. buffer, for example 50% formamide, the temperature under standard conditions is approximately 42° C. The hybridization conditions for DNA: DNA hybrids are, preferably, 0 ,1×SSC and 20° C. to 45 ° C., preferably between 30 ° C. , and 45° C. The hybridization conditions for DNA :RNA hybrids are, preferably, 0,1×SSC and 30° C. to 55° C. preferably between 45 ° and 55 °C. The abovementioned hybridization temperatures are determined for example for a nucleic acid with approximately 100 bp (=base pairs) in length and a G =C content of 50m% in the absence of formamide. The skilled worker knows how to determine the hybridization conditions required by referring to textbooks such as the textbook mentioned above, or the following textbooks: Sambrook et al., “Molecular Cloning”, Cold Spring Harbor Laboratory, 1989; Hames and Higgins (Ed.) 1985, “Nucleic Acids Hybridization: A Practical Approach”, IRL Press at Oxford University Press, Oxford; Brown (Ed.) 1991, “Essential Molecular Biology: A Practical Approach”, IRL Press at Oxford University Press, Oxford. Alternatively, polynucleotide variants are obtainable by PCR-based techniques such as mixed oligonucleotide primer-based amplification of DNA, i,e. using degenerated primers against conserved domains of the polypeptides of the present invention. Conserved domains of the polypeptide of the present invention may be identified by a sequence comparison of the nucleic acid sequences of the polynucleotides or the amino acid sequences of the polypeptides of the present invention. Oligonucleotides suitable as PCR primers as well as suitable PCR conditions are described in the accompanying Examples, As a template, DNA or cDNA from bacteria, fungi, plants or animals may be used. Further, variants include polynucleotides comprising nucleic acid sequences which are at least 50%, at least 55%, at least 60%, at least 65%, at least 70%, at least 756%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98% or at least 99% identical to the nucleic acid sequences shown in any one of SEQ 1 D NOs: 1 or 3 , preferably, encoding polypeptides retaining a ECR activity as specified above. Moreover, also encompassed are polynucleotides which comprise nucleic acid sequences encoding a polypeptide having an amino acid sequences which are at least 50%, at least 55%, at least 60%, at least 65%, at least 70% , at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, at least 98% or at least 99% identical to the amino acid sequences shown in any one of SEQ ID NOs: 2 or 4, wherein the polypeptide, preferably, retains nECR activity as specified above. The percent identity values are, preferably, calculated over the entire amino acid or nucleic acid sequence region. A series of programs based on a variety of algorithms is available to the skilled worker for comparing different sequences. In a preferred embodiment, the percent identity between two amino acid sequences is determined using the Needleman and Wunsch algorithm (Needleman 1970, J. Mol. Biol. (48):444-453) which has been incorporated into the needle program in the EMBOSS software package (EMBOSS: The European Molecular Biology Open 
     Software Suite, Rice,P., Longden,I., and Bleasby,A, Trends in Genetics 1.6(6), 276-277, 2000), using either a BLOSUM 45 or PAM250 scoring matrix for distantly related proteins, or either a BLOSUM 62 or PAM160 scoring matrix for closer related proteins, and a gap opening penalty of 16, 14, 12, 10, 8, 6, or 4 and a gap extension penalty of 0.5, 1, 2, 3, 4, 5, or 6. Guides for local installation of the EMBOSS package as well as links to WEB-Services can be found at emboss.sourceforge.net. A preferred, non-limiting example of parameters to be used for aligning two amino acid sequences using the needle program are the default parameters, including the EBLOSUM62 scoring matrix, a gap opening penalty of 10 and a gap extension penalty of 0.5. In yet another preferred embodiment, the percent identity between two nucleotide sequences is determined using the needle program in the EMBOSS software package (EMBOSS: The European Molecular Biology Open Software Suite, Rice,P., Longden, I., and Bleasby,A, Trends in Genetics 16(6), 276-277 2000), using the EDNAFULL scoring matrix and a gap opening penalty of 16, 14, 12, 10, 8, 6, or 4 and a gap extension penalty of 0.5,1, 2, 3, 4, 5, or 6. A preferred, non-limiting example of parameters to be used in conjunction for aligning two sequences using the needle program are the default parameters, including the EDNAFULL scoring matrix, a gap opening penalty of 10 and a gap extension penalty of 0.5. The nucleic acid and protein sequences of the present invention can further be used as a “query sequence” to perform a search against public databases to, for example, identify other family members or related sequences. Such searches can be performed using the BLAST series of programs (version 2,2) of Altschul et al. (Altschul 1990, J. Mol , Biala 215:403-40). BLAST using nECR nucleic acid sequences of the invention as query sequence can be performed with the BLASTn, BLASTx or the tBLASTx program using default parameters to obtain either nucleotide sequences (BLASTn, tBLASTx) or amino acid sequences (BLASTx) homologous to nECR sequences of the invention. BLAST using nECR protein sequences of the invention as query sequence can be performed with the BLASTp or the tBLASTn program using default parameters to obtain either amino acid sequences (BLASTp) or nucleic acid sequences (tBLASTn) homologous to nECR sequences of the invention. To obtain gapped alignments for comparison purposes, Gapped BLAST using default parameters can be utilized as described in Altschul et al, (Altschul 1997, Nucleic Acids Res. 25(17 ):3389-3402). 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Relation of sequence types of querry- and 
               
               
                 hit-sequences for various BLAST programs 
               
            
           
           
               
               
               
               
               
            
               
                 Input query 
                 Converted 
                   
                 Converted 
                 Actual 
               
               
                 sequence 
                 Query 
                 Algorithm 
                 Hit 
                 Database 
               
               
                   
               
               
                 DNA 
                   
                 BLASTn 
                   
                 DNA 
               
               
                 PRT 
                   
                 BLASTp 
                   
                 PRT 
               
               
                 DNA 
                 PRT 
                 BLASTx 
                   
                 PRT 
               
               
                 PRT 
                   
                 tBLASTn 
                 PRT 
                 DNA 
               
               
                 DNA 
                 PRT 
                 tBLASTx 
                 PRT 
                 DNA 
               
               
                   
               
            
           
         
       
     
     A polynucleotide comprising a fragment of any of the aforementioned nucleic acid sequences is also encompassed as a polynucleotide of the present invention. The fragment shall encode a polypeptide which still has nECR activity as specified above. Accordingly, the polypeptide may comprise or consist of the domains of the polypeptide of the present invention conferring the said biological activity. A fragment as meant herein, preferably, comprises at least 50, at least 100, at least 250 or at least 500 consecutive nucleotides of any one of the aforementioned nucleic acid sequences or encodes an amino acid sequence comprising at least 20, at least 30, at least 50, at least 80, at least 100 or at least 150 consecutive amino acids of any one of the aforementioned amino acid sequences. 
     The variant polynucleotides or fragments referred to above, preferably, encode polypeptides retaining nECR activity to a significant extent, preferably, at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80% or at least 90% of the nECR activity exhibited by any of the polypeptide shown in any one of SEQ ID NOs: 2 or 4. The activity may be tested as described in the accompanying Examples. 
     The polynucleotides of the present invention either essentially consist of the aforementioned nucleic acid sequences or comprise the aforementioned nucleic acid sequences. Thus, they may contain further nucleic acid sequences as well. Preferably, the polynucleotide of the present invention may comprise in addition to an open reading frame further untranslated sequence at the 3′ and at the 5′ terminus of the coding gene region: at least 500, preferably 200, more preferably 100 nucleotides of the sequence upstream of the 5′ terminus of the coding region and at least 100, preferably 50, more preferably 20 nucleotides of the sequence downstream of the 3′ terminus of the coding gene region. Furthermore, the polynucleotides of the present invention may encode fusion proteins wherein one partner of the fusion protein is a polypeptide being encoded by a nucleic acid sequence recited above. Such fusion proteins may comprise as additional part other enzymes of the fatty acid or PUFA biosynthesis pathways, polypeptides for monitoring expression (e.g., green, yellow, blue or red fluorescent proteins, alkaline phosphatase and the like) or so called “tags” which may serve as a detectable marker or as an auxiliary measure for purification purposes. Tags for the different purposes are well known in the art and comprise FLAG-tags, 6-histidine-tags, MYC-tags and the like. 
     The polynucleotide of the present invention shall be provided, preferably, either as an isolated polynucleotide (i.e. purified or at least isolated from its natural context such as its natural gene locus) or in genetically modified or exogenously (i.e. artificially) manipulated form. An isolated polynucleotide can, for example, comprise less than approximately 5 kb, 4 kb, 3 kb, 2 kb, 1 kb, 0.5 kb or 0.1 kb of nucleotide sequences which naturally flank the nucleic acid molecule in the genomic DNA of the cell from which the nucleic acid is derived. The polynucleotide, preferably, is provided in the form of double or single stranded molecule. It will be understood that the present invention by referring to any of the aforementioned polynucleotides of the invention also refers to complementary or reverse complementary strands of the specific sequences or variants thereof referred to before. The polynucleotide encompasses DNA, including cDNA and genomic DNA, or RNA polynucleotides. 
     However, the present invention also pertains to polynucleotide variants which are derived from the polynucleotides of the present invention and are capable of interfering with the transcription or translation of the polynucleotides of the present invention. Such variant polynucleotides include anti-sense nucleic acids, ribozymes, siRNA molecules, morpholino nucleic acids (phosphorodiamidate morpholino oligos), triple-helix forming oligonucleotides, inhibitory oligonucleotides, or micro RNA molecules all of which shall specifically recognize the polynucleotide of the invention due to the presence of complementary or substantially complementary sequences. These techniques are well known to the skilled artisan. Suitable variant polynucleotides of the aforementioned kind can be readily designed based on the structure of the polynucleotides of this invention. 
     Moreover, comprised are also chemically modified polynucleotides including naturally occurring modified polynucleotides such as glycosylated or methylated polynucleotides or artificial modified ones such as biotinylated polynucleotides. 
     In the studies underlying the present invention, advantageously, polynucleotides where identified encoding dehydrateses from  Thalassiosira pseudonana  and  Phaeodactylum tricornumtum . In particular, the  Thalassiosira pseudonana  and  Phaeodactylum  dehydratase/enoyl-CoA-reductase nECR have been identified [nECR(Tp) and nECR(Pt)]. Each of these nECR are capable of removing a hydroxyl group from 3-hydroxy-acyl-CoA and reducing the formed double bond as part of the elongation process for fatty acids. For example, the expression of the nECR(Tp) and nECR(Pt) in a  Saccharomyces cerevisae  mutant not been able to elongate fatty acids has been found to restore the elongation process. The polynucleotides of the present invention are particularly suitable for the recombinant manufacture of LCPUFAs and, in particular, ARA, EPA and/or DHA. 
     In a preferred embodiment of the polynucleotide of the present invention, said polynucleotide further comprises an expression control sequence operatively linked to the said nucleic acid sequence. 
     The term “expression control sequence” as used herein refers to a nucleic acid sequence which is capable of governing, i.e. initiating and controlling, transcription of a nucleic acid sequence of interest, in the present case the nucleic sequences recited above. Such a sequence usually comprises or consists of a promoter or a combination of a promoter and enhancer sequences. Expression of a polynucleotide comprises transcription of the nucleic acid molecule, preferably, into a translatable mRNA. Additional regulatory elements may include transcriptional as well as translational enhancers. The following promoters and expression control sequences may be, preferably, used in an expression vector according to the present invention. The cos, tac, trp, tet, trp-tet, Ipp, Iac, Ipp-Iac, IacIq, T7, T5, T3, gal, trc, ara, SP6, λ-PR or λ-PL promoters are, preferably, used in Gram-negative bacteria. For Gram-positive bacteria, promoters amy and SPO2 may be used. From yeast or fungal promoters ADC1, AOX1r, GAL1, MFα, AC, P-60, CYC1, GAPDH, TEF, rp28, ADH are, preferably, used. For animal cell or organism expression, the promoters CMV-, SV40-, RSV-promoter (Rous sarcoma virus), CMV-enhancer, SV40-enhancer are preferably used. From plants the promoters CaMV/35S (Franck 1980, Cell 21: 285-294], PRP1 (Ward 1993, Plant. Mol. Biol. 22), SSU, OCS, lib4, usp, STLS1, B33, nos or the ubiquitin or phaseolin promoter. Also preferred in this context are inducible promoters, such as the promoters described in EP 0 388 186 A1 (i.e. a benzylsulfonamide-inducible promoter), Gatz 1992, Plant J. 2:397-404 (i.e. a tetracyclin-inducible promoter), EP 0 335 528 A1 (i.e. a abscisic-acid-inducible promoter) or WO 93/21334 (i.e. a ethanol- or cyclohexenol-inducible promoter). Further suitable plant promoters are the promoter of cytosolic FBPase or the ST-LSI promoter from potato (Stockhaus 1989, EMBO J. 8, 2445), the phosphoribosyl-pyrophosphate amidotransferase promoter from Glycine max (Genbank accession No. U87999) or the node-specific promoter described in EP 0 249 676 A1. Particularly preferred are promoters which enable the expression in tissues which are involved in the biosynthesis of fatty acids. Also particularly preferred are seed-specific promoters such as the USP promoter in accordance with the practice, but also other promoters such as the LeB4, DC3, phaseolin or napin promoters. Further especially preferred promoters are seed-specific promoters which can be used for monocotyledonous or dicotyledonous plants and which are described in U.S. Pat. No. 5,608,152 (napin promoter from oilseed rape), WO 98/45461 (oleosin promoter from  Arobidopsis , U.S. Pat. No. 5,504,200 (phaseolin promoter from  Phaseolus vulgaris ), WO 91/13980 (Bce4 promoter from  Brassica ), by Baeumlein et al., Plant J., 2, 2, 1992:233-239 (LeB4 promoter from a legume), these promoters being suitable for dicots. The following promoters are suitable for monocots: Ipt-2 or Ipt-1 promoter from barley (WO 95/15389 and WO 95/23230), hordein promoter from barley and other promoters which are suitable and which are described in WO 99/16890. In principle, it is possible to use all natural promoters together with their regulatory sequences, such as those mentioned above, for the novel process. Likewise, it is possible and advantageous to use synthetic promoters, either additionally or alone, especially when they mediate a seed-specific expression, such as, for example, as described in WO 99/16890. In a particular embodiment, seed-specific promoters are utilized to enhance the production of the desired PUFA or LCPUFA. 
     The term “operatively linked” as used herein means that the expression control sequence and the nucleic acid of interest are linked so that the expression of the said nucleic acid of interest can be governed by the said expression control sequence, i.e. the expression control sequence shall be functionally linked to the said nucleic acid sequence to be expressed. Accordingly, the expression control sequence and, the nucleic acid sequence to be expressed may be physically linked to each other, e.g., by inserting the expression control sequence at the 5′ end of the nucleic acid sequence to be expressed. Alternatively, the expression control sequence and the nucleic acid to be expressed may be merely in physical proximity so that the expression control sequence is capable of governing the expression of at least one nucleic acid sequence of interest. The expression control sequence and the nucleic acid to be expressed are, preferably, separated by not more than 500 bp, 300 bp, 100 bp, 80 bp, 60 bp, 40 bp, 20 bp, 10 by or 5 bp. 
     In a further preferred embodiment of the polynucleotide of the present invention, said polynucleotide further comprises a terminator sequence operatively linked to the nucleic acid sequence. 
     The term “terminator” as used herein refers to a nucleic acid sequence which is capable of terminating transcription. These sequences will cause dissociation of the transcription machinery from the nucleic acid sequence to be transcribed. Preferably, the terminator shall be active in plants and, in particular, in plant seeds. Suitable terminators are known in the art and, preferably, include polyadenylation signals such as the SV40-poly-A site or the tk-poly-A site or one of the plant specific signals indicated in Loke et al. (Loke 2005, Plant Physiol 138, pp. 1457-1468), downstream of the nucleic acid sequence to be expressed. The present invention also relates to a vector comprising the polynucleotide of the present invention. 
     The term “vector”, preferably, encompasses phage, plasmid, viral vectors as well as artificial chromosomes, such as bacterial or yeast artificial chromosomes. Moreover, the term also relates to targeting constructs which allow for random or site- directed integration of the targeting construct into genomic DNA. Such target constructs, preferably, comprise DNA of sufficient length for either homolgous or heterologous recombination as described in detail below. The vector encompassing the polynucleotide of the present invention, preferably, further comprises selectable markers for propagation and/or selection in a host. The vector may be incorporated into a host cell by various techniques well known in the art. If introduced into a host cell, the vector may reside in the cytoplasm or may be incorporated into the genome. In the latter case, it is to be understood that the vector may further comprise nucleic acid sequences which allow for homologous recombination or heterologous insertion. Vectors can be introduced into prokaryotic or eukaryotic cells via conventional transformation or transfection techniques. The terms “transformation” and “transfection”, conjugation and transduction, as used in the present context, are intended to comprise a multiplicity of prior-art processes for introducing foreign nucleic acid (for example DNA) into a host cell, including calcium phosphate, rubidium chloride or calcium chloride co-precipitation, DEAE-dextran-mediated transfection, lipofection, natural competence, carbon-based clusters, chemically mediated transfer, electroporation or particle bombardment. Suitable methods for the transformation or transfection of host cells, including plant cells, can be found in Sambrook et al. (Molecular Cloning: A Laboratory Manual, 2 nd  ed., Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989) and other laboratory manuals, such as Methods in Molecular Biology, 1995, Vol. 44, Agrobacterium protocols, Ed.: Gartland and Davey, Humana Press, Totowa, New Jersey. Alternatively, a plasmid vector may be introduced by heat shock or electroporation techniques. Should the vector be a virus, it may be packaged in vitro using an appropriate packaging cell line prior to application to host cells. 
     Preferably, the vector referred to herein is suitable as a cloning vector, i.e. replicable in microbial systems. Such vectors ensure efficient cloning in bacteria and, preferably, yeasts or fungi and make possible the stable transformation of plants. Those which must be mentioned are, in particular, various binary and co-integrated vector systems which are suitable for the T-DNA-mediated transformation. Such vector systems are, as a rule, characterized in that they contain at least the vir genes, which are required for the Agrobacterium-mediated transformation, and the sequences which delimit the T-DNA (T-DNA border). These vector systems, preferably, also comprise further cis-regulatory regions such as promoters and terminators and/or selection markers with which suitable transformed host cells or organisms can be identified. While co-integrated vector systems have vir genes and T-DNA sequences arranged on the same vector, binary systems are based on at least two vectors, one of which bears vir genes, but no T-DNA, while a second one bears T-DNA, but no vir gene. As a consequence, the last-mentioned vectors are relatively small, easy to manipulate and can be replicated both in E. coli and in Agrobacterium. These binary vectors include vectors from the pBIB-HYG, pPZP, pBecks, pGreen series. Preferably used in accordance with the invention are Bin19, pBI101, pBinAR, pGPTV and pCAMBIA. An overview of binary vectors and their use can be found in Hellens et al, Trends in Plant Science (2000) 5, 446-451. Furthermore, by using appropriate cloning vectors, the polynucleotides can be introduced into host cells or organisms such as plants or animals and, thus, be used in the transformation of plants, such as those which are published, and cited, in: Plant Molecular Biology and Biotechnology (CRC Press, Boca Raton, Florida), chapter 6/7, pp. 71-119 (1993); F. F. White, Vectors for Gene Transfer in Higher Plants; in: Transgenic Plants, vol. 1, Engineering and Utilization, Ed.: Kung and R. Wu, Academic Press, 1993, 15-38; B. Jenes et al., Techniques for Gene Transfer, in: Transgenic Plants, vol. 1, Engineering and Utilization, Ed.: Kung and R. Wu, Academic Press (1993), 128-143; Potrykus 1991, Annu. Rev. Plant Physiol. Plant Molec. Biol. 42, 205-225. 
     More preferably, the vector of the present invention is an expression vector. In such an expression vector, i.e. a vector which comprises the polynucleotide of the invention having the nucleic acid sequence operatively linked to an expression control sequence (also called “expression cassette”) allowing expression in prokaryotic or eukaryotic cells or isolated fractions thereof. Suitable expression vectors are known in the art such as Okayama-Berg cDNA expression vector pcDV1 (Pharmacia), pCDM8, pRc/CMV, pcDNA1, pcDNA3 (Invitrogene) or pSPORT1 (GIBCO BRL). Further examples of typical fusion expression vectors are pGEX (Pharmacia Biotech Inc; Smith 1988, Gene 67:31-40), pMAL (New England Biolabs, Beverly, Mass.) and pRIT5 (Pharmacia, Piscataway, N.J.), where glutathione S-transferase (GST), maltose E-binding protein and protein A, respectively, are fused with the recombinant target protein. Examples of suitable inducible nonfusion  E. coli  expression vectors are, inter alia, pTrc (Amann 1988, Gene 69:301-315) and pET 11d (Studier 1990, Methods in Enzymology 185, 60-89). The target gene expression of the pTrc vector is based on the transcription from a hybrid trp-Iac fusion promoter by host RNA polymerase. The target gene expression from the pET 11d vector is based on the transcription of a T7-gn10-Iac fusion promoter, which is mediated by a coexpressed viral RNA polymerase (T7 gn1). This viral polymerase is provided by the host strains BL21 (DE3) or HMS174 (DE3) from a resident λ-prophage which harbors a T7 gn1 gene under the transcriptional control of the IacUV 5 promoter. The skilled worker is familiar with other vectors which are suitable in prokaryotic organisms; these vectors are, for example, in  E. coli , pLG338, pACYC184, the pBR series such as pBR322, the pUC series such as pUC18 or pUC19, the M113mp series, pKC30, pRep4, pHS1, pHS2, pPLc236, pMBL24, pLG200, pUR290, pIN-III113-B1, λgt11 or pBdCl, in  Streptomyces  pIJ101, pIJ364, pIJ702 or pIJ361, in  Bacillus  pUB110, pC194 or pBD214, in  Corynebacterium  pSA77 or pAJ667. Examples of vectors for expression in the yeast  S. cerevisiae  comprise pYep Sec1 (Baldari 1987, Embo J. 6:229-234), pMFa (Kurjan 1982, Cell 30:933-943), pJRY88 (Schultz 1987, Gene 54:113-123) and pYES2 (lnvitrogen Corporation, San Diego, Calif.). Vectors and processes for the construction of vectors which are suitable for use in other fungi, such as the filamentous fungi, comprise those which are described in detail in: van den Hondel, C. A. M. J. J., &amp; Punt, P. J. (1991) “Gene transfer systems and vector development for filamentous fungi, in: Applied Molecular Genetics of fungi, J. F. Peberdy et al., Ed., pp. 1-28, Cambridge University Press: Cambridge, or in: More Gene Manipulations in Fungi (J. W. Bennett &amp; L. L. Lasure, Ed., pp. 396-428: Academic Press: San Diego). Further suitable yeast vectors are, for example, pAG-1, YEp6, YEp13 or pEMBLYe23. As an alternative, the polynucleotides of the present invention can be also expressed in insect cells using baculovirus expression vectors. Baculovirus vectors which are available for the expression of proteins in cultured insect cells (for example Sf9 cells) comprise the pAc series (Smith 1983, Mol. Cell Biol. 3:2156-2165) and the pVL series (Lucklow 1989, Virology 170:31-39). 
     The polynucleotide of the present invention can be expressed in single-cell plant cells (such as algae), see Falciatore 1999, Marine Biotechnology 1 (3):239-251 and the references cited therein, and plant cells from higher plants (for example  Spermatophytes , such as arable crops) by using plant expression vectors. Examples of plant expression vectors comprise those which are described in detail in: Becker 1992, Plant Mol. Biol. 20:1195-1197; Bevan 1984, Nucl. Acids Res. 12:8711-8721; Vectors for Gene Transfer in Higher Plants; in: Transgenic Plants, Vol. 1, Engineering and Utilization, Ed.: Kung and R. Wu, Academic Press, 1993, p. 15-38. A plant expression cassette, preferably, comprises regulatory sequences which are capable of controlling the gene expression in plant cells and which are functionally linked so that each sequence can fulfill its function, such as transcriptional termination, for example polyadenylation signals. Preferred polyadenylation signals are those which are derived from  Agrobacterium tumefaciens  T-DNA, such as the gene 3 of the Ti plasmid pTiACH5, which is known as octopine synthase (Gielen 1984, EMBO J. 3, 835) or functional equivalents of these, but all other terminators which are functionally active in plants are also suitable. Since plant gene expression is very often not limited to transcriptional levels, a plant expression cassette preferably comprises other functionally linked sequences such as translation enhancers, for example the overdrive sequence, which comprises the 5′-untranslated tobacco mosaic virus leader sequence, which increases the protein/RNA ratio (Gallie 1987, Nucl. Acids Research 15:8693-8711). As described above, plant gene expression must be functionally linked to a suitable promoter which performs the expression of the gene in a timely, cell-specific or tissue-specific manner. Promoters which can be used are constitutive promoters (Benfey 1989, EMBO J. 8:2195-2202) such as those which are derived from plant viruses such as 35S CAMV (Franck 1980, Cell 21:285-294), 19S CaMV (see U.S. Pat. No. 5,352,605 and WO 84/02913) or plant promoters such as the promoter of the Rubisco small subunit, which is described in U.S. Pat. No. 4,962,028. Other preferred sequences for the use in functional linkage in plant gene expression cassettes are targeting sequences which are required for targeting the gene product into its relevant cell compartment (for a review, see Kermode 1996, Crit. Rev. Plant Sci. 15, 4: 285-423 and references cited therein), for example into the vacuole, the nucleus, all types of plastids, such as amyloplasts, chloroplasts, chromoplasts, the extracellular space, the mitochondria, the endoplasmic reticulum, oil bodies, peroxisomes and other compartments of plant cells. As described above, plant gene expression can also be facilitated via a chemically inducible promoter (for a review, see Gatz 1997, Annu. Rev. Plant Physiol. Plant Mol. Biol., 48:89-108). Chemically inducible promoters are particularly suitable if it is desired that genes are expressed in a time-specific manner. Examples of such promoters are a salicylic-acid-inducible promoter (WO 95/19443), a tetracyclin-inducible promoter (Gatz 1992, Plant J. 2, 397-404) and an ethanol-inducible promoter. Promoters which respond to biotic or abiotic stress conditions are also suitable promoters, for example the pathogen-induced PRP1-gene promoter (Ward 1993, Plant Mol. Biol. 22:361-366), the heat-inducible hsp80 promoter from tomato (U.S. Pat. No. 5,187,267), the cold-inducible alpha-amylase promoter from potato (WO 96/12814) or the wound-inducible pinII promoter (EP 0 375 091 A). The promoters which are especially preferred are those which bring about the expression of genes in tissues and organs in which fatty acid, lipid and oil biosynthesis takes place, in seed cells such as the cells of endosperm and of the developing embryo. Suitable promoters are the napin gene promoter from oilseed rape (U.S. Pat. No. 5,608,152), the USP promoter from  Vicia faba  (Baeumlein 1991, Mol. Gen. Genet. 225 (3):459-67), the oleosin promoter from  Arabidopsis  (WO 98/45461), the phaseolin promoter from  Phaseolus vulgaris  (U.S. Pat. No. 5,504,200), the Bce4 promoter from  Brassica  (WO 91/13980) or the legumin B4 promoter (LeB4; Baeumlein 1992, Plant Journal, 2 (2):233-9), and promoters which bring about the seed-specific expression in monocotyledonous plants such as maize, barley, wheat, rye, rice and the like. Suitable promoters to be taken into consideration are the lpt2 or lpt1 gene promoter from barley (WO 95/15389 and WO 95/23230) or those which are described in WO 99/16890 (promoters from the barley hordein gene, the rice glutelin gene, the rice oryzin gene, the rice prolamin gene, the wheat gliadin gene, wheat glutelin gene, the maize zein gene, the oat glutelin gene, the sorghum kasirin gene, the rye secalin gene). Likewise, especially suitable are promoters which bring about the plastid-specific expression since plastids are the compartment in which the precursors and some end products of lipid biosynthesis are synthesized. Suitable promoters such as the viral RNA-polymerase promoter, are described in WO 95/16783 and WO 97/06250, and the clpP promoter from  Arabidopsis , described in WO 99/46394. 
     The abovementioned vectors are only a small overview of vectors to be used in accordance with the present invention. Further vectors are known to the skilled worker and are described, for example, in: Cloning Vectors (Ed., Pouwels, P. H., et al., Elsevier, Amsterdam-New York-Oxford, 1985, ISBN 0 444 904018). For further suitable expression systems for prokaryotic and eukaryotic cells see the chapters 16 and 17 of Sambrook, loc cit. 
     It follows from the above that, preferably, said vector is an expression vector. More preferably, the said polynucleotide of the present invention is under the control of a seed-specific promoter in the vector of the present invention. A preferred seed-specific promoter as meant herein is selected from the group consisting of Conlinin 1, Conlinin 2, napin, LuFad3, USP, LeB4, Arc, Fae, ACP, LuPXR, and SBP. For details, see, e.g., US 2003-0159174. 
     Moreover, the present invention relates to a host cell comprising the polynucleotide or the vector of the present invention. 
     Preferably, said host cell is a plant cell and, more preferably, a plant cell obtained from an oilseed crop. More preferably, said oilseed crop is selected from the group consisting of flax ( Linum  sp.), rapeseed ( Brassica  sp.), soybean ( Glycine  and  Soja  sp.), sunflower ( Helianthus  sp.), cotton ( Gossypium  sp.), corn ( Zea mays ), olive ( Olea  sp.), safflower ( Carthamus  sp.), cocoa ( Theobroma cacoa ), peanut ( Arachis  sp.), hemp, camelina, crambe, oil palm, coconuts, groundnuts, sesame seed, castor bean, lesquerella, tallow tree, sheanuts, tungnuts, kapok fruit, poppy seed, jojoba seeds and perilla. 
     Also preferably, said host cell is a microorganism. More preferably, said microorganism is a bacterium, a fungus or algae. More preferably, it is selected from the group consisting of  Candida, Cryptococcus, Lipomyces, Rhodosporidium, Yarrowia , and,  Schizochytrium.    
     Moreover, a host cell according to the present invention may also be an animal cell. Preferably, said animal host cell is a host cell of a fish or a cell line obtained therefrom. More preferably, the fish host cell is from herring, salmon, sardine, redfish, eel, carp, trout, halibut, mackerel, zander or tuna. 
     Generally, the controlling steps in the production of LCPUFAs, i.e., the long chain unsaturated fatty acid biosynthetic pathway, are catalyzed by membrane-associated fatty acid elongase complexes. Plants and most other eukaryotic organisms have specialized elongase system for the extension of fatty acids beyond C18 atoms. These elongase reactions have several important features in common with the fatty acid synthase complex (FAS). However, the elongase complex is different from the FAS complex as the complex is localized in the cytosol and are membrane bound, ACP is not involved and the elongase 3-keto-acyl-CoA-synthase catalyzes the condensation of malonyl-CoA with an acyl primer. The elongase complex consists of four components with different catalytic functions, the keto-acyl-CoA-synthase (KCS, condensation reaction of malonyl-CoA to acyl-CoA, creation of a 2 C atom longer keto-acyl-CoA fatty acid), the keto-acyl-CoA-reductase (KCR, reduction of the 3-keto group to a 3-hydroxy-group), the dehydratase (DH, dehydration results in a delta-2-enoyl-acyl-CoA fatty acid) and the enoly-CoA-reductase (ECR, reduction of the double bond at position 2, release from the complex). For the production of LCPUFAs including ARA, EPA and/or DHA the elongation reaction could be essential. Higher plants do not have the necessary enzyme set to produce LCPUFAs (4 or more double bonds, 20 or more C atoms). Therefore the catalytic activities have to be conferred to the plants or plant cells. One critical step in the process of elongation is the dehydration and reduction reaction. The polynucleotides of the present invention surprisingly catalyze the dehydration and reduction activity by one enzyme. By delivering this nECR increased levels of PUFAs and LCPUFAs are produced. 
     However, it will be understood that dependent on the host cell, further, enzymatic activities may be conferred to the host cells, e.g., by recombinant technologies. Accordingly, the present invention, preferably, envisages a host cell which in addition to the polynucleotide of the present invention comprises polynucleotides encoding such desaturases and/or elongases as required depending on the selected host cell. Preferred desaturases and/or elongases which shall be present in the host cell are at least one enzyme selected from the group consisting of: Δ-4-desaturase, Δ-5-desaturase, Δ-5-elongase, Δ-6-desaturase, Δ12-desaturase, Δ15-desaturase, ω3-desaturase and Δ-6-elongase. Especially preferred are the bifunctional d12d15-desaturases d12d15Des(Ac) from  Acanthamoeba castellanii  (WO2007042510), d12d15Des(Cp) from  Claviceps purpurea  (WO2008006202) and d12d15Des(Lg)1 from  Lottia gigantea  (WO2009016202), the d12-desaturases d12Des(Co) from  Calendula officinalis  (WO200185968), d12Des(Lb) from  Laccaria bicolor  (WO2009016202), d12Des(Mb) from  Monosiga brevicollis  (WO2009016202), dl2Des(Mg) from  Mycosphaerella graminicola  (WO2009016202), d12Des(Nh) from  Nectria haematococca  (WO2009016202), d12Des(Ol) from  Ostreococcus lucimarinus  (WO2008040787), d12Des(Pb) from  Phycomyces blakesleeanus  (WO2009016202), dl2Des(Ps) from  Phytophthora sojae  (WO2006100241) and d12Des(Tp) from  Thalassiosira pseudonana  (WO2006069710), the d15-desaturases d15Des(Hr) from  Helobdella robusta  (WO2009016202), d15Des(Mc) from  Microcoleus chthonoplastes  (WO2009016202), d15Des(Mf) from  Mycosphaerella fijiensis  (WO2009016202), d15Des(Mg) from  Mycosphaerella graminicola  (WO2009016202) and d15Des(Nh)2 from  Nectria haematococca  (WO2009016202), the d4-desaturases d4Des(Eg) from  Euglena gracilis  (WO2004090123), d4Des(Tc) from  Thraustochytrium  sp. (WO2002026946) and d4Des(Tp) from  Thalassiosira pseudonana  (WO2006069710), the d5-desaturases d5Des(Ol)2 from  Ostreococcus lucimarinus  (WO2008040787), d5Des(Pp) from  Physcomitrella patens  (WO2004057001), d5Des(Pt) from  Phaeodactylum tricornutum  (WO2002057465), d5Des(Tc) from  Thraustochytrium  sp. (WO2002026946), d5Des(Tp) from  Thalassiosira pseudonana  (WO2006069710) and the d6-desaturases d6Des(Cp) from  Ceratodon purpureus  (WO2000075341), d6Des(Ol) from  Ostreococcus lucimarinus  (WO2008040787), d6Des(Ot) from  Ostreococcus tauri  (WO2006069710), d6Des(Pf) from  Primula farinosa  (WO2003072784), d6Des(Pir)_BO from  Pythium irregulare  (WO2002026946), d6Des(Pir) from  Pythium irregulare  (WO2002026946), d6Des(Plu) from  Primula luteola  (WO2003072784), d6Des(Pp) from  Physcomitrella patens  (WO200102591), d6Des(Pt) from  Phaeodactylum tricornutum  (WO2002057465), d6Des(Pv) from  Primula vialii  (WO2003072784) and d6Des(Tp) from  Thalassiosira pseudonana  (WO2006069710), the d8-desaturases d8Des(Ac) from  Acanthamoeba castellanii  (EP1790731), d8Des(Eg) from  Euglena gracilis  (WO200034439) and d8Des(Pm) from  Perkinsus marinus  (WO2007093776), the o3-desaturases o3Des(Pi) from  Phytophthora infestans  (WO2005083053), o3Des(Pir) from  Pythium irregulare  (WO2008022963), o3Des(Pir)2 from  Pythium irregulare  (WO2008022963) and o3Des(Ps) from  Phytophthora sojae  (WO2006100241), the bifunctional d5d6-elongases d5d6EIo(Om)2 from  Oncorhynchus mykiss  (WO2005012316), d5d6EIo(Ta) from  Thraustochytrium aureum  (WO2005012316) and d5d6EIo(Tc) from  Thraustochytrium  sp. (WO2005012316), the d5-elongases d5EIo(At) from  Arabidopsis thaliana  (WO2005012316), d5EIo(At)2 from  Arabidopsis thaliana  (WO2005012316), d5EIo(Ci) from  Ciona intestinalis  (WO2005012316), d5EIo(Ol) from  Ostreococcus lucimarinus  (WO2008040787), d5EIo(Ot) from  Ostreococcus tauri  (WO2005012316), d5EIo(Tp) from  Thalassiosira pseudonana  (WO2005012316) and d5EIo(Xl) from  Xenopus laevis  (WO2005012316), the d6-elongases d6EIo(Ol) from  Ostreococcus lucimarinus  (WO2008040787), d6EIo(Ot) from  Ostreococcus tauri  (WO2005012316), d6EIo(Pi) from  Phytophthora infestans  (WO2003064638), d6EIo(Pir) from  Pythium irregulare  (WO2009016208), d6EIo(Pp) from  Physcomitrella patens  (WO2001059128), d6EIo(Ps) from  Phytophthora sojae  (WO2006100241), d6EIo(Ps)2 from  Phytophthora sojae  (WO2006100241), d6Elo(Ps)3 from  Phytophthora sojae  (WO2006100241), d6EIo(Pt) from  Phaeodactylum tricornutum  (WO2005012316), d6EIo(Tc) from  Thraustochytrium  sp. (WO2005012316) and d6EIo(Tp) from  Thalassiosira pseudonana  (WO2005012316), the d9-elongases d9EIo(Ig) from  Isochrysis galbana  (WO2002077213), d9EIo(Pm) from  Perkinsus marinus  (WO2007093776) and d9EIo(Ro) from  Rhizopus oryzae  (WO2009016208). Particularly, if the manufuacture of ARA is envisaged in higher plants, the enzymes recited in Table 3, below (i.e. additionally a d6-desaturase, d6-elongase, d5-elongase, d5-desaturase, d12-desaturase, and d6-elongase) or enzymes having essentially the same activity may be combined in a host cell. If the manufacture of EPA is envisaged in higher plants, the enzymes recited in Table 4, below (i.e. additionally a d6-desaturase, d6-elongase, d5-desaturase, d12-desaturase, d6-elongase, omega 3-desaturase and d15-desaturase), or enzymes having essentially the same activity may be combined in a host cell. If the manufacture of DHA is envisaged in higher plants, the enzymes recited in Table 5, below (i.e. additionally a d6-desaturase, d6-elongase, d5-desaturase, d12-desaturase, d6-elongase, omega 3-desaturase, d15-desaturase, d5-elongase, and d4-desaturase), or enzymes having essentially the same activity may be combined in a host cell. 
     The present invention also relates to a cell, preferably a host cell as specified above or a cell of a non-human organism specified elsewhere herein, said cell comprising a polynucleotide which is obtained from the polynucleotide of the present invention by a point mutation, a truncation, an inversion, a deletion, an addition, a substitution and homologous recombination. How to carry out such modifications to a polynucleotide is well known to the skilled artisan and has been described elsewhere in this specification in detail. 
     The present invention furthermore pertains to a method for the manufacture of a polypeptide encoded by a polynucleotide of any the present invention comprising
         a) cultivating the host cell of the invention under conditions which allow for the production of the said polypeptide; and   b) obtaining the polypeptide from the host cell of step a).       

     Suitable conditions which allow for expression of the polynucleotide of the invention comprised by the host cell depend on the host cell as well as the expression control sequence used for governing expression of the said polynucleotide. These conditions and how to select them are very well known to those skilled in the art. The expressed polypeptide may be obtained, for example, by all conventional purification techniques including affinity chromatography, size exclusion chromatography, high pressure liquid chromatography (HPLC) and precipitation techniques including antibody precipitation. It is to be understood that the method may—although preferred—not necessarily yield an essentially pure preparation of the polypeptide. It is to be understood that depending on the host cell which is used for the aforementioned method, the polypeptides produced thereby may become posttranslationally modified or processed otherwise. 
     The present invention encompasses a polypeptide encoded by the polynucleotide of of the present invention or which is obtainable by the aforementioned method. 
     The term “polypeptide” as used herein encompasses essentially purified polypeptides or polypeptide preparations comprising other proteins in addition. Further, the term also relates to the fusion proteins or polypeptide fragments being at least partially encoded by the polynucleotide of the present invention. referred to above. Moreover, it includes chemically modified polypeptides. Such modifications may be artificial modifications or naturally occurring modifications such as phosphorylation, glycosylation, myristylation and the like (Review in Mann 2003, Nat, Biotechnol. 21, 255-261, review with focus on plants in Huber 2004, Curs, Opin. Plant Biol, 7, 318-322), Currently, more than 300 posttranslational modifications are known (see full ABM: Delta mass list at abrf.org/idex.cfm/dm.home). The polypeptide of the present invention shall exhibit the n ECR activitiy referred to above. 
     Encompassed by the present invention is, furthermore, an antibody which specifically recognizes the polypeptide of the invention. 
     Antibodies against the polypeptides of the invention can be prepared by well known methods using a purified polypeptide according to the invention or a suitable fragment derived therefrom as an antigen. A fragment which is suitable as an antigen may be identified by antigenicity determining algorithms well known in the art. Such fragments may be obtained either from the polypeptide of the invention by proteolytic digestion or may be a synthetic peptide. Preferably, the antibody of the present invention is a monoclonal antibody, a polyclonal antibody, a single chain antibody, a chimerized antibody or a fragment of any of these antibodies, such as Fab, Fv or scFv fragments etc. Also comprised as antibodies by the present invention are bispecific antibodies, synthetic antibodies or chemically modified derivatives of any of the aforementioned antibodies. The antibody of the present invention shall specifically bind (i.e. does significantly not cross react with other polypeptides or peptides) to the polypeptide of the invention. Specific binding can be tested by various well known techniques. Antibodies or fragments thereof can be obtained by using methods which are described, e.g., in Harlow and Lane “Antibodies, A Laboratory Manual”, CSH Press, Cold Spring Harbor, 1988. Monoclonal antibodies can be prepared by the techniques originally described in Köhler 1975, Nature 256, 495, and Galfré 1981, Meth. Enzymol. 73, 3, which comprise the fusion of mouse myeloma cells to spleen cells derived from immunized mammals. The antibodies can be used, for example, for the immunoprecipitation, immunolocalization or purification (e.g., by affinity chromatography) of the polypeptides of the invention as well as for the monitoring of the presence of said variant polypeptides, for example, in recombinant organisms, and for the identification of proteins or compounds interacting with the proteins according to the invention. 
     Moreover, the present invention contemplates a non-human transgenic organism comprising the polynucleotide or the vector of the present invention. 
     Preferably, the non-human transgenic organism is a plant, plant part, or plant seed. Preferred plants to be used for introducing the polynucleotide or the vector of the invention are plants which are capable of synthesizing fatty acids, such as all dicotyledonous or monocotyledonous plants, algae or mosses. It is to be understood that host cells derived from a plant may also be used for producing a plant according to the present invention. Preferred plants are selected from the group of the plant families Adelotheciaceae, Anacardiaceae, Asteraceae, Apiaceae, Betulaceae, Boraginaceae, Brassicaceae, Bromeliaceae, Caricaceae, Cannabaceae, Convolvulaceae, Chenopodiaceae, Crypthecodiniaceae, Cucurbitaceae, Ditrichaceae, Elaeagnaceae, Ericaceae, Euphorbiaceae, Fabaceae, Geraniaceae, Gramineae, Juglandaceae, Lauraceae, Leguminosae, Linaceae, Prasinophyceae or vegetable plants or ornamentals such as Tagetes. Examples which may be mentioned are the following plants selected from the group consisting of: Adelotheciaceae such as the genera  Physcomitrella , such as the genus and species  Physcomitrella patens , Anacardiaceae such as the genera  Pistacia, Mangifera, Anacardium , for example the genus and species  Pistacia vera  [pistachio],  Mangifer indica  [mango] or  Anacardium occidentale  [cashew], Asteraceae, such as the genera  Calendula, Carthamus, Centaurea, Cichorium, Cynara, Helianthus, Lactuca, Locusta, Tagetes, Valeriana , for example the genus and species  Calendula officinalis  [common marigold],  Carthamus tinctorius  [safflower],  Centaurea cyanus  [cornflower],  Cichorium intybus  [chicory],  Cynara scolymus  [artichoke],  Helianthus annus  [sunflower],  Lactuca sativa, Lactuca crispa, Lactuca esculenta, Lactuca scariola  L. ssp.  sativa, Lactuca scariola  L. var.  integrate, Lactuca scariola  L. var.  integrifolia, Lactuca sativa  subsp.  romana, Locusta communis, Valeriana locusta  [salad vegetables],  Tagetes lucida, Tagetes erecta  or  Tagetes tenuifolia  [african or french marigold], Apiaceae, such as the genus  Daucus , for example the genus and species  Daucus carota  [carrot], Betulaceae, such as the genus  Corylus , for example the genera and species  Corylus avellana  or  Corylus colurna  [hazelnut], Boraginaceae, such as the genus  Borago , for example the genus and species  Borago officinalis  [borage], Brassicaceae, such as the genera  Brassica, Melanosinapis, Sinapis, Arabadopsis , for example the genera and species  Brassica napus, Brassica rapa  ssp. [oilseed rape],  Sinapis arvensis Brassica juncea, Brassica juncea  var.  juncea, Brassica juncea  var.  crispifolia, Brassica juncea  var.  foliosa, Brassica nigra, Brassica sinapioides, Melanosinapis communis  [mustard],  Brassica oleracea  [fodder beet] or  Arabidopsis thaliana , Bromeliaceae, such as the genera  Anana, Bromelia  (pineapple), for example the genera and species  Anana comosus, Ananas ananas  or  Bromelia comosa  [pineapple], Caricaceae, such as the genus  Carica , such as the genus and species  Carica papaya  [pawpaw], Cannabaceae, such as the genus  Cannabis , such as the genus and species  Cannabis sativa  [hemp], Convolvulaceae, such as the genera  Ipomea, Convolvulus , for example the genera and species  Ipomoea batatus, Ipomoea pandurata, Convolvulus batatas, Convolvulus tiliaceus, Ipomoea fastigiata, Ipomoea tiliacea, Ipomoea triloba  or  Convolvulus panduratus  [sweet potato, batate], Chenopodiaceae, such as the genus  Beta , such as the genera and species  Beta vulgaris, Beta vulgaris  var.  altissima, Beta vulgaris  var.  Vulgaris, Beta maritima, Beta vulgaris  var.  perennis, Beta vulgaris  var.  conditiva  or  Beta vulgaris  var.  esculenta  [sugarbeet], Crypthecodiniaceae, such as the genus  Crypthecodinium , for example the genus and species  Cryptecodinium cohnii , Cucurbitaceae, such as the genus  Cucurbita , for example the genera and species  Cucurbita maxima, Cucurbita mixta, Cucurbita pepo  or  Cucurbita moschata  [pumpkin/squash], Cymbellaceae such as the genera  Amphora, Cymbella, Okedenia, Phaeodactylum, Reimeria , for example the genus and species  Phaeodactylum tricornutum , Ditrichaceae such as the genera  Ditrichaceae, Astomiopsis, Ceratodon, Chrysoblastella, Ditrichum, Distichium, Eccremidium, Lophidion, Philibertiella, Pleuridium, Saelania, Trichodon, Skottsbergia , for example the genera and species  Ceratodon antarcticus, Ceratodon columbiae, Ceratodon heterophyllus, Ceratodon purpureus, Ceratodon purpureus, Ceratodon purpureus  ssp.  convolutus, Ceratodon, purpureus  spp.  stenocarpus, Ceratodon purpureus  var.  rotundifolius, Ceratodon ratodon, Ceratodon stenocarpus, Chrysoblastella chilensis, Ditrichum ambiguum, Ditrichum brevisetum, Ditrichum crispatissimum, Ditrichum difficile, Ditrichum falcifolium, Ditrichum flexicaule, Ditrichum giganteum, Ditrichum heteromallum, Ditrichum lineare, Ditrichum lineare, Ditrichum montanum, Ditrichum montanum, Ditrichum pallidum, Ditrichum punctulatum, Ditrichum pusillum, Ditrichum pusillum var. tortile, Ditrichum rhynchostegium, Ditrichum schimperi, Ditrichum tortile, Distichium capillaceum, Distichium hagenii, Distichium inclinatum, Distichium macounii, Eccremidium floridanum, Eccremidium whiteleggei, Lophidion strictus, Pleuridium acuminatum, Pleuridium alternifolium, Pleuridium holdridgei, Pleuridium mexicanum, Pleuridium ravenelii, Pleuridium subulatum, Saelania glaucescens, Trichodon borealis, Trichodon cylindricus  or  Trichodon cylindricus  var.  oblongus , Elaeagnaceae such as the genus  Elaeagnus , for example the genus and species  Olea europaea  [olive], Ericaceae such as the genus  Kalmia , for example the genera and species  Kalmia latifolia, Kalmia angustifolia, Kalmia microphylla, Kalmia polifolia, Kalmia occidentalis, Cistus chamaerhodendros  or  Kalmia lucida  [mountain laurel], Euphorbiaceae such as the genera  Manihot, Janipha, Jatropha, Ricinus , for example the genera and species  Manihot utilissima, Janipha manihot, Jatropha manihot, Manihot aipil, Manihot dulcis, Manihot manihot, Manihot melanobasis, Manihot esculenta  [manihot] or  Ricinus communis  [castor-oil plant], Fabaceae such as the genera  Pisum, Albizia, Cathormion, Feuillea, Inga, Pithecolobium, Acacia, Mimosa, Medicajo, Glycine, Dolichos, Phaseolus, Soja , for example the genera and species  Pisum sativum, Pisum arvense, Pisum humile  [pea],  Albizia berteriana, Albizia julibrissin, Albizia lebbeck, Acacia berteriana, Acacia littoralis, Albizia berteriana, Albizzia berteriana, Cathormion berteriana, Feuillea berteriana, Inga fragrans, Pithecellobium berterianum, Pithecellobium fragrans, Pithecolobium berterianum, Pseudalbizzia berteriana, Acacia julibrissin, Acacia nemu, Albizia nemu, Feuilleea julibrissin, Mimosa julibrissin, Mimosa speciosa, Sericanrda julibrissin, Acacia lebbeck, Acacia macrophylla, Albizia lebbek, Feuilleea lebbeck, Mimosa lebbeck, Mimosa speciosa  [silk tree],  Medicago sativa, Medicago falcata, Medicago varia  [alfalfa],  Glycine max Dolichos soja, Glycine gracilis, Glycine hispida, Phaseolus max, Soja hispida  or  Soja max  [soybean], Funariaceae such as the genera  Aphanorrhegma, Entosthodon, Funaria, Physcomitrella, Physcomitrium , for example the genera and species  Aphanorrhegma serratum, Entosthodon attenuatus, Entosthodon bolanderi, Entosthodon bonplandii, Entosthodon californicus, Entosthodon drummondii, Entosthodon jamesonii, Entosthodon leibergii, Entosthodon neoscoticus, Entosthodon rubrisetus, Entosthodon spathulifolius, Entosthodon tucsoni, Funaria americana, Funaria bolanderi, Funaria calcarea, Funaria californica, Funaria calvescens, Funaria convoluta, Funaria flavicans, Funaria groutiana, Funaria hygrometrica, Funaria hygrometrica  var.  arctica, Funaria hygrometrica  var.  calvescens, Funaria hygrometrica  var.  convoluta, Funaria hygrometrica  var.  muralis, Funaria hygrometrica  var.  utahensis, Funaria microstoma, Funaria microstoma  var.  obtusifolia, Funaria muhlenbergii, Funaria orcuttii, Funaria plano-convexa, Funaria polaris, Funaria ravenelii, Funaria rubriseta, Funaria serrata, Funaria sonorae, Funaria sublimbatus, Funaria tucsoni, Physcomitrella californica, Physcomitrella patens, Physcomitrella readeri, Physcomitrium australe, Physcomitrium californicum, Physcomitrium collenchymatum, Physcomitrium coloradense, Physcomitrium cupuliferum, Physcomitrium drummondii, Physcomitrium eurystomum, Physcomitrium flexifolium, Physcomitrium hookeri, Physcomitrium hookeri  var. serratum,  Physcomitrium immersum, Physcomitrium kellermanii, Physcomitrium megalocarpum, Physcomitrium pyriforme, Physcomitrium pyriforme  var.  serratum, Physcomitrium rufipes, Physcomitrium sandbergii, Physcomitrium subsphaericum, Physcomitrium washingtoniense , Geraniaceae, such as the genera  Pelargonium, Cocos, Oleum , for example the genera and species  Cocos nucifera, Pelargonium grossularioides  or  Oleum cocois  [coconut], Gramineae, such as the genus  Saccharum , for example the genus and species  Saccharum officinarum , Juglandaceae, such as the genera  Juglans, Wallia , for example the genera and species  Juglans regia, Juglans ailanthifolia, Juglans sieboldiana, Juglans cinerea, Wallia cinerea, Juglans bixbyi, Juglans californica, Juglans hindsii, Juglans intermedia, Juglans jamaicensis, Juglans major, Juglans microcarpa, Juglans nigra  or  Wallia nigra  [walnut], Lauraceae, such as the genera  Persea, Laurus , for example the genera and species  Laurus nobilis  [bay],  Persea americana, Persea gratissima  or  Persea persea  [avocado], Leguminosae, such as the genus  Arachis , for example the genus and species  Arachis hypogaea  [peanut], Linaceae, such as the genera  Linum, Adenolinum , for example the genera and species  Linum usitatissimum, Linum humile, Linum austriacum, Linum bienne, Linum angustifolium, Linum catharticum, Linum flavum, Linum grandiflorum, Adenolinum grandiflorum, Linum lewisii, Linum narbonense, Linum perenne, Linum perenne  var.  lewisii, Linum pratense  or  Linum trigynum  [linseed], Lythrarieae, such as the genus  Punica , for example the genus and species  Punica granatum  [pomegranate], Malvaceae, such as the genus  Gossypium , for example the genera and species  Gossypium hirsutum, Gossypium arboreum, Gossypium barbadense, Gossypium herbaceum  or  Gossypium thurberi  [cotton], Marchantiaceae, such as the genus  Marchantia , for example the genera and species  Marchantia berteroana, Marchantia foliacea, Marchantia macropora , Musaceae, such as the genus  Musa , for example the genera and species  Musa nana, Musa acuminata, Musa paradisiaca, Musa  spp. [banana], Onagraceae, such as the genera  Camissonia, Oenothera , for example the genera and species  Oenothera biennis  or  Camissonia brevipes  [evening primrose], Palmae, such as the genus  Elacis , for example the genus and species  Elaeis guineensis  [oil palm], Papaveraceae, such as the genus  Papaver , for example the genera and species  Papaver orientale, Papaver rhoeas, Papaver dubium  [poppy], Pedaliaceae, such as the genus  Sesamum , for example the genus and species  Sesamum indicum  [sesame], Piperaceae, such as the genera  Piper, Artanthe, Peperomia, Steffensia , for example the genera and species  Piper aduncum, Piper amalago, Piper angustifolium, Piper auritum, Piper betel, Piper cubeba, Piper longum, Piper nigrum, Piper retrofractum, Artanthe adunca, Artanthe elongata, Peperomia elongata, Piper elongatum, Steffensia elongata  [cayenne pepper], Poaceae, such as the genera  Hordeum, Secale, Avena, Sorghum, Andropogon, Holcus, Panicum, Oryza, Zea  (maize),  Triticum , for example the genera and species  Hordeum vulgare, Hordeum jubatum, Hordeum murinum, Hordeum secalinum, Hordeum distichon, Hordeum aegiceras, Hordeum hexastichon, Hordeum hexastichum, Hordeum irregulare, Hordeum sativum, Hordeum secalinum  [barley],  Secale cereale  [rye],  Avena sativa, Avena fatua, Avena byzantina, Avena fatua  var.  sativa, Avena hybrida  [oats],  Sorghum bicolor, Sorghum halepense, Sorghum saccharatum, Sorghum vulgare, Andropogon drummondii, Holcus bicolor, Holcus sorghum, Sorghum aethiopicum, Sorghum arundinaceum, Sorghum caffrorum, Sorghum cernuum, Sorghum dochna, Sorghum drummondii, Sorghum durra, Sorghum guineense, Sorghum lanceolatum, Sorghum nervosum, Sorghum saccharatum, Sorghum subglabrescens, Sorghum verticilliflorum, Sorghum vulgare, Holcus halepensis, Sorghum miliaceum, Panicum militaceum  [millet],  Oryza sativa, Oryza latifolia  [rice],  Zea mays  [maize],  Triticum aestivum, Triticum durum, Triticum turgidum, Triticum hybernum, Triticum macha, Triticum sativum or Triticum vulgare  [wheat], Porphyridiaceae, such as the genera  Chroothece, Flintiella, Petrovanella, Porphyridium, Rhodella, Rhodosorus, Vanhoeffenia , for example the genus and species  Porphyridium cruentum , Proteaceae, such as the genus  Macadamia , for example the genus and species  Macadamia intergrifolia  [macadamia], Prasinophyceae such as the genera  Nephroselmis, Prasinococcus, Scherffelia, Tetraselmis, Mantoniella, Ostreococcus , for example the genera and species  Nephroselmis olivacea, Prasinococcus capsulatus, Scherffelia dubia, Tetraselmis chui, Tetraselmis suecica, Mantoniella squamata, Ostreococcus tauri , Rubiaceae such as the genus  Cofea , for example the genera and species  Cofea  spp.,  Coffea arabica, Coffea canephora  or  Coffea liberica  [coffee], Scrophulariaceae such as the genus  Verbascum , for example the genera and species  Verbascum blattaria, Verbascum chaixii, Verbascum densiflorum, Verbascum lagurus, Verbascum longifolium, Verbascum lychnitis, Verbascum nigrum, Verbascum olympicum, Verbascum phlomoides, Verbascum phoenicum, Verbascum pulverulentum or Verbascum thapsus  [mullein], Solanaceae such as the genera  Capsicum, Nicotiana, Solanum, Lycopersicon , for example the genera and species  Capsicum annuum, Capsicum annuum  var.  glabriusculum, Capsicum frutescens  [pepper],  Capsicum annuum  [paprika],  Nicotiana tabacum, Nicotiana alata, Nicotiana attenuata, Nicotiana glauca, Nicotiana langsdorffii, Nicotiana obtusifolia, Nicotiana quadrivalvis, Nicotiana repanda, Nicotiana rustica, Nicotiana sylvestris  [tobacco],  Solanum tuberosum  [potato],  Solanum melongena  [eggplant],  Lycopersicon esculentum, Lycopersicon lycopersicum, Lycopersicon pyriforme, Solanum integrifolium  or  Solanum lycopersicum  [tomato], Sterculiaceae, such as the genus  Theobroma , for example the genus and species  Theobroma cacao [cacao] or Theaceae, such as the genus  Camellia , for example the genus and species  Camellia sinensis  [tea]. In particular preferred plants to be used as transgenic plants in accordance with the present invention are oil fruit crops which comprise large amounts of lipid compounds, such as peanut, oilseed rape, canola, sunflower, safflower, poppy, mustard, hemp, castor-oil plant, olive, sesame,  Calendula, Punica , evening primrose, mullein, thistle, wild roses, hazelnut, almond, macadamia, avocado, bay, pumpkin/squash, linseed, soybean, pistachios, borage, trees (oil palm, coconut, walnut) or crops such as maize, wheat, rye, oats, triticale, rice, barley, cotton, cassava, pepper,  Tagetes, Solanaceae  plants such as potato, tobacco, eggplant and tomato,  Vicia  species, pea, alfalfa or bushy plants (coffee, cacao, tea),  Salix  species, and perennial grasses and fodder crops. Preferred plants according to the invention are oil crop plants such as peanut, oilseed rape, canola, sunflower, safflower, poppy, mustard, hemp, castor-oil plant, olive,  Calendula, Punica , evening primrose, pumpkin/squash, linseed, soybean, borage, trees (oil palm, coconut). Especially preferred are sunflower, safflower, tobacco, mullein, sesame, cotton, pumpkin/squash, poppy, evening primrose, walnut, linseed, hemp, thistle or safflower. Very especially preferred plants are plants such as safflower, sunflower, poppy, evening primrose, walnut, linseed, or hemp. 
     Preferred mosses are  Physcomitrella  or  Ceratodon . Preferred algae are  Isochrysis, Mantoniella, Ostreococcus  or  Crypthecodinium , and algae/diatoms such as  Phaeodactylum  or  Thraustochytrium . More preferably, said algae or mosses are selected from the group consisting of:  Shewanella, Physcomitrella, Thraustochytrium, Fusarium, Phytophthora, Ceratodon, Isochrysis, Aleurita, Muscarioides, Mortierella, Phaeodactylum, Cryphthecodinium , specifically from the genera and species  Thallasiosira pseudonona, Euglena gracilis, Physcomitrella patens, Phytophtora infestans, Fusarium graminaeum, Cryptocodinium cohnii, Ceratodon purpureus, Isochrysis galbana, Aleurita farinosa, Thraustochytrium  sp.,  Muscarioides viallii, Mortierella alpina, Phaeodactylum tricornutum  or  Caenorhabditis elegans  or especially advantageously  Phytophtora infestans, Thallasiosira pseudonona  and  Cryptocodinium cohnii.    
     Transgenic plants may be obtained by transformation techniques as elsewhere in this specification. Preferably, transgenic plants can be obtained by T-DNA-mediated transformation. Such vector systems are, as a rule, characterized in that they contain at least the vir genes, which are required for the Agrobacterium-mediated transformation, and the sequences which delimit the T-DNA (T-DNA border). Suitable vectors are described elsewhere in the specification in detail. 
     Also encompassed are transgenic non-human animals comprising the vector or polynucleotide of the present invention. Preferred non-human transgenic animals envisaged by the present invention are fish, such as herring, salmon, sardine, redfish, eel, carp, trout, halibut, mackerel, zander or tuna. 
     However, it will be understood that dependent on the non-human transgenic organism specified above, further, enzymatic activities may be conferred to the said organism, e.g., by recombinant technologies. Accordingly, the present invention, preferably, envisages a non-human transgenic organism specified above which in addition to the polynucleotide of the present invention comprises polynucleotides encoding such desaturases and/or elongases as required depending on the selected host cell. Preferred desaturases and/or elongases which shall be present in the organism are at least one enzyme selected from the group of desaturases and/or elongases or the combinations specifically recited elsewhere in this specification (see above and Tables 3, 4 and 5). 
     Furthermore, the present invention encompasses a method for the manufacture of polyunsaturated fatty acids comprising:
         a) cultivating the host cell of the invention under conditions which allow for the production of polyunsaturated fatty acids in said host cell; and   b) obtaining said polyunsaturated fatty acids from the said host cell.       

     The term “polyunsaturated fatty acids (PUFA)” as used herein refers to fatty acids comprising at least two, preferably, three, four, five or six, double bonds. Moreover, it is to be understood that such fatty acids comprise, preferably from 18 to 24 carbon atoms in the fatty acid chain. More preferably, the term relates to long chain PUFA (LCPUFA) having from 20 to 24 carbon atoms in the fatty acid chain. Preferred unsaturated fatty acids in the sense of the present invention are selected from the group consisting of DGLA 20:3 (8,11,14), ARA 20:4 (5,8,11,14), iARA 20:4(8,11,14,17), EPA 20:5 (5,8,11,14,17), DPA 22:5 (4,7,10,13,16), DHA 22:6 (4,7,10,13,16,19), 20:4 (8,11,14,17), more preferably, arachidonic acid (ARA) 20:4 (5,8,11,14), eicosapentaenoic acid (EPA) 20:5 (5,8,11,14,17), and docosahexaenoic acid (DHA) 22:6 (4,7,10,13,16,19). Thus, it will be understood that most preferably, the methods provided by the present invention pertaining to the manufacture of ARA, EPA or DHA. Moreover, also encompassed are the intermediates of LCPUFA which occur during synthesis. Such intermediates are, preferably, formed from substrates by the nECR activity of the polypeptide of the present invention. Preferably, substrates encompass LA 18:2 (9,12), GLA 18:3 (6,9,12), DGLA 20:3 (8,11,14), ARA 20:4 (5,8,11,14), eicosadienoic acid 20:2 (11,14), Eicosatetraenoic acid 20:4 (8,11,14,17), Eicosapentaenoic acid 20:5 (5,8,11,14,17). 
     The term “cultivating” as used herein refers maintaining and growing the host cells under culture conditions which allow the cells to produce the said polyunsaturated fatty acid, i.e. the PUFA and/or LCPUFA referred to above. This implies that the polynucleotide of the present invention is expressed in the host cell so that the nECR activity is present. Suitable culture conditions for cultivating the host cell are described in more detail below. 
     The term “obtaining” as used herein encompasses the provision of the cell culture including the host cells and the culture medium as well as the provision of purified or partially purified preparations thereof comprising the polyunsaturated fatty acids, preferably, ARA, EPA, DHA, in free or in —CoA bound form, as membrane phospholipids or as triacylglyceride estres. More preferably, the PUFA and LCPUFA are to be obtained as triglyceride esters, e.g., in form of an oil. More details on purification techniques can be found elsewhere herein below. 
     The host cells to be used in the method of the invention are grown or cultured in the manner with which the skilled worker is familiar, depending on the host organism. Usually, host cells are grown in a liquid medium comprising a carbon source, usually in the form of sugars, a nitrogen source, usually in the form of organic nitrogen sources such as yeast extract or salts such as ammonium sulfate, trace elements such as salts of iron, manganese and magnesium and, if appropriate, vitamins, at temperatures of between 0° C. and 100° C., preferably between 10° C. and 60° C. under oxygen or anaerobic atmosphere dependent on the type of organism. The pH of the liquid medium can either be kept constant, that is to say regulated during the culturing period, or not. The cultures can be grown batchwise, semibatchwise or continuously. Nutrients can be provided at the beginning of the fermentation or administered semicontinuously or continuously: The produced PUFA or LCPUFA can be isolated from the host cells as described above by processes known to the skilled worker, e.g., by extraction, distillation, crystallization, if appropriate precipitation with salt, and/or chromatography. It might be required to disrupt the host cells prior to purification. To this end, the host cells can be disrupted beforehand. The culture medium to be used must suitably meet the requirements of the host cells in question. Descriptions of culture media for various microorganisms which can be used as host cells according to the present invention can be found in the textbook “Manual of Methods for General Bacteriology” of the American Society for Bacteriology (Washington D.C., USA, 1981). Culture media can also be obtained from various commercial suppliers. All media components are sterilized, either by heat or by filter sterilization. All media components may be present at the start of the cultivation or added continuously or batchwise, as desired. If the polynucleotide or vector of the invention which has been introduced in the host cell further comprises an expressible selection marker, such as an antibiotic resistance gene, it might be necessary to add a selection agent to the culture, such as a antibiotic in order to maintain the stability of the introduced polynucleotide. The culture is continued until formation of the desired product is at a maximum. This is normally achieved within 10 to 160 hours. The fermentation broths can be used directly or can be processed further. The biomass may, according to requirement, be removed completely or partially from the fermentation broth by separation methods such as, for example, centrifugation, filtration, decanting or a combination of these methods or be left completely in said broth. The fatty acid preparations obtained by the method of the invention, e.g., oils, comprising the desired PUFA or LCPUFA as triglyceride esters are also suitable as starting material for the chemical synthesis of further products of interest. For example, they can be used in combination with one another or alone for the preparation of pharmaceutical or cosmetic compositions, foodstuffs, or animal feeds. Chemically pure triglycerides comprising the desired PUFA or LCPUFA can also be manufactured by the methods described above. To this end, the fatty acid preparations are further purified by extraction, distillation, crystallization, chromatography or combinations of these methods. In order to release the fatty acid moieties from the triglycerides, hydrolysis may be also required. The said chemically pure triglycerides or free fatty acids are, in particular, suitable for applications in the food industry or for cosmetic and pharmacological compositions. 
     Moreover, the present invention relates to a method for the manufacture of poly-unsaturated fatty acids comprising:
         a) cultivating the non-human transgenic organism of the invention under conditions which allow for the production of poly-unsaturated fatty acids in said host cell; and   b) obtaining said poly-unsaturated fatty acids from the said non-human transgenic organism.       

     Further, it follows from the above that a method for the manufacture of an oil, lipid or fatty acid composition is also envisaged by the present invention comprising the steps of any one of the aforementioned methods and the further step of formulating PUFA or LCPUFA as oil, lipid or fatty acid composition. Preferably, said oil, lipid or fatty acid composition is to be used for feed, foodstuffs, cosmetics or medicaments. Accordingly, the formulation of the PUFA or LCPUFA shall be carried out according to the GMP standards for the individual envisaged products. For example, an oil may be obtained from plant seeds by an oil mill. However, for product safety reasons, sterilization may be required under the applicable GMP standard. Similar standards will apply for lipid or fatty acid compositions to be applied in cosmetic or pharmaceutical compositions. All these measures for formulating oil, lipid or fatty acid compositions as products are comprised by the aforementioned manufacture. 
     The present invention also relates to an oil comprising a polyunsaturated fatty acid obtainable by the aforementioned methods. 
     The term “oil” refers to a fatty acid mixture comprising unsaturated and/or saturated fatty acids which are esterified to triglycerides. Preferably, the triglycerides in the oil of the invention comprise PUFA or LCPUFA as referred to above. The amount of esterified PUFA and/or LCPUFA is, preferably, approximately 30%, a content of 50% is more preferred, a content of 60%, 70%, 80% or more is even more preferred. The oil may further comprise free fatty acids, preferably, the PUFA and LCPUFA referred to above. For the analysis, the fatty acid content can be, e.g., determined by GC analysis after converting the fatty acids into the methyl esters by transesterification. The content of the various fatty acids in the oil or fat can vary, in particular depending on the source. The oil, however, shall have a non-naturally occurring composition with respect to the PUFA and/or LCPUFA composition and content. It will be understood that such a unique oil composition and the unique esterification pattern of PUFA and LCPUFA in the triglycerides of the oil shall only be obtainable by applying the methods of the present invention specified above. Moreover, the oil of the invention may comprise other molecular species as well. Specifically, it may comprise minor impurities of the polynucleotide or vector of the invention. Such impurities, however, can be detected only by highly sensitive techniques such as PCR. 
     The contents of all references cited throughout this application are herewith incorporated by reference in general and with respect to their specific disclosure content referred to above. 
    
    
     
       FIGURES 
         FIG. 1  shows the nucleotide (SEQ ID NO: 1) and amino acid sequences of nECR from  Thalassiosira pseudonana  (SEQ ID NO: 2). 
         FIG. 2  shows the nucleotide and amino acid sequence of nECR from  Phaeodactylum tricornutum  as follows: A) the cDNA sequence of the mRNA (SEQ ID NO:3); B) the translated amino acid sequence (SEQ ID NO:4) 
         FIG. 3  shows an Alignment of the amino acid sequences from nECR from  T. pseudonana  and  P. tricornutum  with the dehydratase (YJL097W) and enoyl-CoA-reductase (YDL015C) from Saccharomyces cerevisae    
         FIG. 4  shows the similarity table of the aligment from  FIG. 3 . The identity table was done by ClustalW alignment using the Align program from the Vector NTI software package (Invitrogen). The two nECR from the different organisms share 65% identity whereas both nECR have below 30% identity to the known dehydratase (YJL097w) or enoyl-CoA-reductase (YDL015C) from yeast. 
         FIG. 5  shows the functional characterization of nECR(Tp) and nECR(Pt) by yeast complementation assay. The complementation assay was performed with nECR(Tp) and nECR(Pt) in yeast Δydl015c, which has no functional enoyl-CoA-reductase. Legend: YPD, complete medium, SD-Ura, medium lacking uracil, SD-Leu, medium lacking leucine, FOA, medium containing leucine and 5-FOA; (1)tsc13ΔTrp pTSC13 URA: yeast mutant Δydl015C lacking the function of the enoyl-CoA-reductase, transformed with the vector pTSC13 containing the functional YDL015C gene; (2) phs1Δκan pPHS1 URA: yeast mutant Δyjl097w lacking the function of the dehydratase, transformed with the vector pPHS1 containing the functional YJL097W gene; (3) tsc13ΔTrp pESC-nECR(Tp): yeast mutant Δydl015C lacking the function of the enoyl-CoA-reductase, transformed with the vector pESC-nECR(Tp); (4) sc13ΔTrp pESC-nECR(Pt): yeast mutant Δydl015C lacking the function of the enoyl-CoA-reductase, transformed with the vector pESC-nECR(Pt) 
         FIG. 6  shows the increased production of long-chain PUFA with nECR(Tp). Increased production of long-chain PUFA with nECR(Tp). Yeast transformed with pYES-d9EIo(Ig) (A) or pYES-d9EIo(Ig)+pESC-nECR(Tp) (B) were fed with 25 μM linolenic acid (18:3Δ9,12,15) in the SD(-Ura-Leu) medium. After 48 h of incubation the yeast cells were centrifuged and the pellets subjected to gas chromatographic analysis. The gas chromatographs show the different fatty acids in the two different yeast strains without (A) and with nECR(Tp) (B). Conversion rates are figured as following: (product/substrate-product)*100. 
         FIG. 7  shows a Western Blot analysis of  T. pseudonana  subcellular fractions. M, protein size marker, 1, total extract, 2, soluble fraction, 3, membrane fraction. The arrows indicate the two versions of nECR(Tp). 
         FIG. 8  shows a Western Blot analysis of subcellular fractions from yeast expressing nECR(Tp). M, protein size marker, 1, total extract, 2, soluble fraction, 3, membrane fraction. The arrow indicates the nECR(Tp) fusion protein. 
         FIG. 9  shows a Western Blot analysis of subcellular fractions from yeast expressing nECR(Tp). M, protein size marker, 1, total extract, 2, soluble fraction, 3, membrane fraction. The arrow indicates the nECR(Tp) fusion protein. 
     
    
    
     This invention is further illustrated by the following examples which should not be construed as limiting. The contents of all references, patents and published patent applications cited throughout this application, as well as the figures, are incorporated herein by reference. 
     EXAMPLES 
     Example 1 
     Organisms and Culture Conditions 
     For regeneration of haploids, the method outlined in Pan et al 2004 (Molecular Cell 16:487-496) was used. Briefly, cultures were grown overnight in DOB-uracil, then approximately 25 OD 600  of each culture was washed and resuspended in fresh media and grown for 3 hours. Cells were then suspended in sporulation media (1% potassium acetate, 0.005% zinc acetate), sporulated for 5 days and spread on haploid selection magic media plates (2% galactose, amino acid mix—uracil-leucine-histidine-arginine, 0.17% nitrogen base without amino acids or ammonium sulfate, 0.1% sodium glutamate) containing 200 mg/L G418 and 60 mg/L canavanine. 
     Example 2 
     Novel Dehydratase/Enoyl-CoA-Reducatase Sequences 
     PUFA producing algae were screened to reveal differences between non-PUFA producers. Sequences from  Thalassiosira  and  Phaeodactylum  were obtained, which are specific for these PUFA producers ( FIGS. 1 and 2 ). Alignment with known dehydratase and enoyl-CoA-reductase sequences from yeast (YJL097W and YDL015C) showed low homology ( FIGS. 3 and 4 ). Therefore the newly generated nECR represents a novel class of enzymes. By complementation assays (Example 3) the sequences exhibit dehydratase and enoyl-CoA-reducatase activity and were therefore termed nECR. 
     A list of identified full-length coding sequences is shown in Table 1a and 1b. 
     
       
         
           
               
             
               
                 TABLE 1a 
               
             
            
               
                   
               
               
                 List of full-length coding sequences 
               
            
           
           
               
               
               
               
            
               
                 SEQ ID NO: 
                 Gene 
                 Organism 
                 Length in bp 
               
               
                   
               
               
                 1 
                 nECR(Tp) 
                 
                   Thalassiosira pseudonana 
                 
                 2367 
               
               
                 3 
                 nECR(Pt) 
                 
                   Phaeodactylum tricornutum 
                 
                 2244 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 1b 
               
             
            
               
                   
               
               
                 List of deduced amino acids from sequences described in Table 1, 
               
            
           
           
               
               
               
               
            
               
                   
                   
                   
                 Length in 
               
               
                 SEQ ID NO: 
                 Gene 
                 Organism 
                 amino acids 
               
               
                   
               
               
                 2 
                 nECR(Tp) 
                 
                   Thalassiosira pseudonana 
                 
                 788 
               
               
                 4 
                 nECR(Pt) 
                 
                   Phaeodactylum tricornutum 
                 
                 747 
               
               
                   
               
            
           
         
       
     
     Open reading frames as shown in Table 1 were cloned into the pESC(Leu) vector from Stratagene according to manufactures reaction conditions. Reactions were transformed into  E. coli  DH5α and plasmid DNA was isolated. The plasmids pESC-nECR(Tp), pESC-nECR(Pt) were then used for yeast transformation. As both mutant yeast strains Δydl015C (Δtsc13) and Δyjl097w (Δphs1) are lethal, the strains have been transformed with plasmids complementing the mutant with uracil-auxothropie marker URA (pTSC13 and pPHS1). Vectors containing the URA marker can be removed in yeast by using 5-FOA (5-fluoroorotic acid; Sadowski et al. Yeast. 2008 Aug; 25 (8):595-9). 
     Example 3 
     Yeast Transformation and Growth Conditions 
       S. cerevisiae  strain YSC1021-674054 from Open Biosystems was transformed with the constructs pESC-nECR(Tp), pESC-nECR(Pt) and pESC using the S. C. EasyComp Transformation Kit (Invitrogen, Carlsbad, California) with selection on leucine-deficient medium. For assessing the dehydratase/enoyl-CoA-reductase activity complementation studies were done. For that purpose the heterozygous magic marker strain YSC1021-674054 from Open Biosystems was used. This strain does not exhibit any enoyl-CoA-reductase activity. As the enoyl-CoA-reductase activity delivers elongated fatty acids and these fatty acids are required for cell growth and division, the respective yeast strain will not grow on medium not containing said elongated fatty acids. 
     Following Transformats were Generated:
         1. tsc13ΔTrp pTSC13 URA: yeast mutant Δydl015C lacking the function of the enoyl-CoA-reductase, transformed with the vector pTSC13 containing the functional YDL015C gene.   2. phs1Δκan pPHS1 URA: yeast mutant Δyjl097w lacking the function of the dehydratase, transformed with the vector pPHS1 containing the functional YJL097W gene.   3. tsc13ΔTrp pESC-nECR(Tp): yeast mutant Δydl015C lacking the function of the enoyl-CoA-reductase, transformed with the vector pESC-nECR(Tp)   4. sc13ΔTrp pESC-nECR(Pt): yeast mutant Δydl015C lacking the function of the enoyl-CoA-reductase, transformed with the vector pESC-nECR(Pt)       

     Yeast were grown after transformation in complete medium containing all amino acids and nucleotides. Then yeast were plated on different medium containing either the complete medium (SD), the complete medium lacking uracil (SD-Ura), the complete medium lacking leucine (SD-Leu) or the complete medium lacking leucine and containing 5-FOA ( FIG. 5 ). Plasmids 1 and 2 can grow on SD and SD-Ura, but not on SD-Leu as they are not having the LEU marker. Plasmids 3 and 4 can grow on SD and SD-Leu, but not on SD-Ura as they are missing the URA marker. The complementation is shown on plates containing FOA, which removes plasmids with the URA marker (1 and 2). However, even in the absence of plasmids 1 or 2 there is growth of colonies with plasmids 3 and 4 ( FIG. 5 , FOA). 
     Therefore both sequences nECR(Tp) and nECR(Pt) are capable of complementing the lethal null mutation in the yeast 3-hydroxy acyl-CoA dehydratase gene Δydl015C. 
     In summary, by complementation of a defective yeast mutant it could been shown that the sequences nECR(Tp) and nECR(Pt) are biological functional and exhibit enoyl-CoA-reductase activity. 
     Example 4 
     Expression of nECR(Tp) in Combination with the d9-elongase from  Isochrysis galbana    
     To examine the utility of nECR(Tp) in the production of polyunsaturated fatty acids in plants, for example, for nutraceutical use, the gene was expressed in combination with a PUFA-elongase component, the d9-elongase from lsochrysis galbana (WO2002/077213). This enzyme catalyzes the elongation of linoleic or linolenic acid (18:2Δ9,12 or 18:3Δ9,12,15). The aim of the experiment was to analyze, if the addition of nECR(Tp) increases the productivity of the d9-elongase from  I. galbana . For that purpose yeast cells (INVSC from Invitrogen) transformed with pESC-nECR(Tp) and grown on DOB(-leucine) plates were further transformed with the plasmid pYES(Ura)-d9EIo(Ig) as described in Example 1 and grown on DOB(-uracil, -leucine). The vector pYES(Ura) was derived from Invitrogene and mediates auxotrophy for uracil. The open reading frame of d9EIo(Ig) as described in WO2002/077213 was cloned into pYES2 according to manufactures conditions. As a control experiment pYES-d9EIo(Ig) was transformed into the control yeast strain containing only the pYES vector. 
     Surprisingly a difference in the amount of the elongation product 20:3 between the control (pESC-d9EIo(Ig) and the yeast containing two components of the elongation complex (pESC-d9EIo(Ig)+pYES-nECR(Tp) was observed. 
     In  FIG. 6  it is shown that the addition of the nECR(Tp) gene has an tremendous influence on the productivity of long-chain PUFA. Productivity was increased 8-fold compared to the control experiment. The productivity is measured in the conversion of the substrate 18:3 (exogenously added to the yeast medium) to the elongated PUFA fatty acid 20:3. 
     In summary nECR improves greatly the production of elongated fatty acids, such as long-chain PUFA beneficial for human health. 
     Example 5 
     Comparison of Yeast Expressed nECR(Tp) and the Native Protein from  T. pseudonana    
     Antibodies against nECR(Tp) have been produced according to manufactures practice (Eurogentec, Belgium; peptide antibody). The antibodies are highly specific for nECR(Tp) in  T. pseudonana  and the heterologous expression in yeast ( FIG. 7  and  FIG. 8 ). With the use of the antibodies structural differences between the natural organism and the heterologous expression could be observed ( FIG. 7  and  FIG. 8 ). 
     Western Blot experiments were Done Using Standard Protocols: 
     SDS-PAGE was done according to Laemmli (1970) with precast gels from Biorad. As loading buffer 0.05 M Tris/HCl pH6.8, 0.1 M DTT, 2% (w/v) SDS, 0.1% Bromphenolic blue and 10% Glycerol was used. SDS-PAGE gels were then blotted on nitrocellulose using a Protean BA85 nitrocellulose membrane (Schleicher&amp;Schuell). Transfers on the membranes were done with a buffer containing 15 mM Na 2 HPO 4  pH7.2, 0.05% (w/v) SDS, 20% (v/v) Methanol for 2 h at 200 mA, 40 V (Protean II, Biorad). For the immunological test the membrane was blocked for 1 h in PBS (0.14M NaCl, 2.7 mM KCl, 10 mM Na 2 HPO 4 , 1.8 mM KH 2 PO 4  pH7.4), 5% (w/v) milk powder. The serum containing the antibodies against nECR(Tp) was added at a concentration of 1:2000 and incubated overnight at 4° C. For detection of the antibodies the membrane was washed three times with PBS and blocked again with PBS, 5% (w/v) milk powder for 30 min. One unit of secondary antibody (Biorad anti-rabbit horse radish peroxidase) was added and further incubated for 30 min. After three times washing with PBS the membrane was immersed in ECL solution and 1 min incubated. Then the solution was removed with a paper tissue and the membrane was wrapped with Saran. Detection of the chemiluminiscence was done in the Biollluminator (LKB). 
     For protein isolation from  T. pseudonana , a culture of 500 mL was incubated for 14 days at 20° C. in F2 medium (growth conditions and media for  T. pseudonana  used as described in Tonon et al. (Tono 2005, FEBS J. 272:3401-3412). The algae was harvested by centrifucation (10 min, 5000× g) and the pellet was put into a mortar. Using a pistil a fine powder was generated. The powder was suspended with 50 mM Tris/HCl pH 8.0, 2 mM EDTA and filtered through 2 layers of Miracloth (Merck) or any other filter membrane. The filter product was then aliquoted and aliquots of 50 uL were mixed with SDS-PAGE loading buffer (see above). 
     Analysis of the nECR(Tp) detected by Western Blot in  T. pseudonana  ( FIG. 7 ) showed that the protein of nECR(Tp) can be found in the cell debris, soluble and membrane fraction. Surprisingly in  T. pseudonana  the major form is a cleaved version which contains only the enoyl-CoA reductase activity (ECR). The proof for the ECR domain is deduced from the location of the binding site of the antibodies in the ECR domain. The larger fusion protein of nECR(Tp) is found only in small quantities in the soluble fraction. No nECR(Tp) could be found in the membrane fraction, even after longer exposure times. 
     Therefore it can be concluded that in  T. pseudonana  there are two versions of nECR(Tp), the protein as deduced from the cDNA (SEQ ID NO 1) and a post-translationally modified shorter version containing only the ECR domain. Only the ECR domain is membrane bound and therefore correctly localized (functionality of ECR in the elongase complex takes place at the microsomal membranes (Napier 2007, Annu Rev Plant Biol 58:295-319)). 
     With the heterologous expression of nECR(Tp) in yeast a different picture can be observed. As described in Example 4 yeast with pESC-nECR(Tp) was used for protein extraction. Yeast was grown for 3 d at 28° C. in 50 ml cultures and pellets were harvested by centrifugation (10 min, 5000× g). The pellet was aliquoted, frozen with liquid nitrogen and a steel bead added compatible with the Qiagen/Tresch mill system. Pellets were subjected to 5 min in the Tresch mill for cell disruption. Total cell extracts were separated in soluble and membrane fraction by a 30 min 100,000×g centrifugation step. The pellet constitutes the membrane fraction, the supernatant the soluble one. All three fractions were subjected to SDS-PAGE and Western analysis as described above and analyzed ( FIG. 8 ). In yeast no cleavage of nECR(Tp) could be observed. From the molecular weight the yeast expressed fusion protein runs at approx. 86 kDa which is comparable to nECR(Tp) in  T. pseudonana . No 59 kDa ECR cleaved version is present. Therefore it can be concluded that nECR(Tp) as it complements the yeast KO mutants (Example 3) is fully functional in it&#39;s uncleaved form, thereby representing a new class of proteins. Further, the soluble and microsomal fractions were analyzed in detail to check if there is any soluble fraction of nECR(Tp) ( FIG. 9 ). Again supernatant and microsomal fraction was loaded on a gel and exposed for a longer time. No nECR(Tp) could be found in the soluble fraction, again showing a structural difference to the native version from  T. pseudonana.    
     In conclusion a new fusion protein was discovered which surprisingly contains two enzyme activities of the elongation complex (ECR and DH). SEQ ID NO. 1 results in the expression in heterologous systems in a functional fusion protein, which has different structural properties than the native proteins in  T. pseudonana.    
     Example 6 
     Expression of nECR(Tp) and nECR(Pt) in Plants 
     The novel nECR from  T. pseudonana  and  P. tricornutum  are cloned into a plant transformation vector as described in WO2003/093482, WO20051083093 or WO2007/093776. Exemplary suitable combinations of genes are described in Table 3, 4 and 5. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Gene combinations for the production of ARA. 
               
            
           
           
               
               
               
               
            
               
                   
                 Gene 
                 Aktivität 
                 SEQ ID NO: 
               
               
                   
                   
               
               
                   
                 D6Des(Ot) 
                 Δ6-Desaturase 
                 5 
               
               
                   
                 D6Elo(Pp) 
                 Δ6-Elongase 
                 6 
               
               
                   
                 D5Des(Tc) 
                 Δ5-Desaturase 
                 7 
               
               
                   
                 D12Des(Ps) 
                 Δ12-Desaturase 
                 8 
               
               
                   
                 D6Elo(Tp) 
                 Δ6-Elongase 
                 9 
               
               
                   
                 nECR(Tp) or nECR(Pt) 
                 nECR 
                 1 or 3 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Gene combinations for the production of EPA. 
               
            
           
           
               
               
               
               
            
               
                   
                 Gene 
                 Aktivität 
                 SEQ ID NO: 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 D6Des(Ot) 
                 Δ6-Desaturase 
                 5 
               
               
                   
                 D6Elo(Pp) 
                 Δ6-Elongase 
                 6 
               
               
                   
                 D5Des(Tc) 
                 Δ5-Desaturase 
                 7 
               
               
                   
                 D12Des(Ps) 
                 Δ12-Desaturase 
                 8 
               
               
                   
                 D6Elo(Tp) 
                 Δ6-Elongase 
                 9 
               
               
                   
                 (3-Des(Pi) 
                 Omega 3-Desaturase 
                 10 
               
               
                   
                 D15Des(Cp) 
                 Δ15-Desaturase 
                 11 
               
               
                   
                 nECR(Tp) or nECR(Pt) 
                 nECR 
                 1 or 3 
               
               
                   
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Gene combinations for the production of DHA. 
               
            
           
           
               
               
               
               
            
               
                   
                 Gene 
                 Aktivität 
                 SEQ ID NO: 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                 D6Des(Ot) 
                 Δ6-Desaturase 
                 5 
               
               
                   
                 D6Elo(Pp) 
                 Δ6-Elongase 
                 6 
               
               
                   
                 D5Des(Tc) 
                 Δ5-Desaturase 
                 7 
               
               
                   
                 D12Des(Ps) 
                 Δ12-Desaturase 
                 8 
               
               
                   
                 D6Elo(Tp) 
                 Δ6-Elongase 
                 9 
               
               
                   
                 ω3-Des(Pi) 
                 Omega 3-Desaturase 
                 10 
               
               
                   
                 D15Des(Cp) 
                 Δ15-Desaturase 
                 11 
               
               
                   
                 D5Elo(Ot) 
                 Δ5-elongase 
                 12 
               
               
                   
                 D4Des(Tc) 
                 Δ4-desaturase 
                 13 
               
               
                   
                 nECR(Tp) or nECR(Pt) 
                 nECR 
                 1 or 3 
               
               
                   
                   
               
            
           
         
       
     
     Transgenic rapeseed lines are generated as described in Deblaere et al, 1984, Nucl. Acids. Res. 13, 4777-4788 and seeds of transgenic rapeseed plants are analyzed as described in Qiu et al. 2001, J. Biol. Chem. 276, 31561-31566. 
     Reference List 
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     Broadwater, J. A., Whittle, E., and Shanklin, J. (2002). Desaturation and hydroxylation. Residues 148 and 324 of Arabidopsis FAD2, in addition to substrate chain length, exert a major influence in partitioning of catalytic specificity. J. Biol. Chem. 277, 15613-15620. 
     Broun, P., Shanklin, J., Whittle, E., and Somerville, C. (1998b). Catalytic plasticity of fatty acid modification enzymes underlying chemical diversity of plant lipids. Science 282, 1315-1317. 
     Calvo, A. M., Gardner, H. W., and Keller, N. P. (2001). Genetic connection between fatty acid metabolism and sporulation in  Aspergillus nidulans . J. Biol. Chem. 276, 25766-25774. 
     Knutzon, D. S., Thurmond, J. M., Huang, Y. S., Chaudhary, S., Bobik, E. G., Jr., Chan, G. M., Kirchner, S. J., and Mukerji, P. (1998). Identification of Delta5-dehydratase from  Mortierella alpina  by heterologous expression in Bakers&#39; yeast and canola. J. Biol. Chem. 273, 29360-29366. 
     Mantle, P. G. and Nisbet, L. J. (1976). Differentiation of  Claviceps purpurea  in axenic culture. J. Gen. Microbial. 93, 321-334. 
     Mey, G., Oeser, B., Lebrun, M. H., and Tudzynski, P. (2002). The biotrophic, non-appressorium-forming grass pathogen  Claviceps purpurea  needs a Fus3/Pmk1 homologous mitogen-activated protein kinase for colonization of rye ovarian tissue. Mol. Plant Microbe Interact. 15, 303-312. 
     Okuley, J., Lightner, J., Feldmann, K., Yadav, N., Lark, E., and Browse, J. (1994). Arabidopsis FAD2 gene encodes the enzyme that is essential for polyunsaturated lipid synthesis. Plant Cell 6, 147-158. 
     Qi, B., Fraser, T., Mugford, S., Dobson, G., Sayanova, O., Butler, J., Napier, J. A., Stobart, A. K., and Lazarus, C. M. (2004). Production of very long chain polyunsaturated omega-3 and omega-6 fatty acids in plants. Nat. Biotechnol. 22, 739-745. Shanklin, J. and Cahoon, E. B. (1998). DESATURATION AND RELATED MODIFICATIONS OF FATTY ACIDS1. Annu. Rev. Plant Physiol Plant Mol. Biol. 49, 611-641. 
     Tudzynski, P., Correia, T., and Keller, U. (2001). Biotechnology and genetics of ergot alkaloids. Appl. Microbial. Biotechnol. 57, 593-605. 
     All references cited in this specification are herewith incorporated by reference with respect to their entire disclosure content and the disclosure content specifically mentioned in this specification.