THE PRESENT DISCLOSURE RELATES TO ISOLATED POLYNUCLEOTIDES ENCODING A DELTA 9- ELONGASE, DELTA 9-.ELONGASES ENCODED BY THE ISOLATED POLYNUCLEOTIDES, EXPRESSION VECTORS COMPRISING THE ISOLATED POLYNUCLEOTIDES, HOST CELLS COMPRISING THE EXPRESSION VECTORS, AND METHODS FOR PRODUCING DELTA 9-ELONGASE AND POLYUNSATURATED FATTY ACIDS