A6-Desaturase gene

Several plants A6-desaturase genes have been cloned from Anemone leveillei, borago [211], three Echium species, Marchantia polymorpha. Primula farcinosa, P. vialii and P. juliae, as well as from fungi Mortierella alpine, M. isabelina, Mucor rouxii [205] and Pythium irregulare, from the diatom Phaeodactylum tricornutum [203] and from mosses the Ceratodom purpureus and Physcomitrella patens [212], although not all of them have been expressed in plants. 

Production of Functional y-Linolenic Acid (GLA) by Expression of Fungal A12- and A6-Desaturase Genes in the Oleaginous Yeast Yarrowia lipolytica... 

A6-desaturase genes allowed the conversion of endogenous oleic acid (OA A9-18 l) to LA by the A12-desaturase, and the newly synthesized LA was then A6-desaturated to form GLA. This result indicates that single-cell oils (SCOs) from edible yeasts could be another substitute for more expensive plant oils. 

To construct a plasmid for simultaneous expression of A12- and A6-desaturase genes, we designed a pair of primers with homology, respectively, to the 5 end and the 3 end of the seqnence of A12-desaturase expression cassette (hp4d promoter/A12-... 

FIGURE 12.1 Plasmids used to transform Yarrowia lipolytica Polg strain for expression of, respectively, Mortierella alpina A6-desatnrase gene (A), A12-desatnrase gene (B), or both A12- and A6-desaturase genes (C). 

FIGURE 12.2 Gas chromatogram of fatty acids of total lipids in the yeasts transformed with empty vector [Polg(pYLEXl)] or the yeasts carrying the Mortierella A6-desaturase gene [Polg(pYLd6)]. Solid arrows show the presence of A6,9-16 2, A6,9-18 2, and y-linolenic acid (A6,9,12-18 3), the A6-desaturation products of A9-16 l, A9-18 l, and linoleic acid (A9,12-18 2), respectively. 

Results described demonstrate that recombinant A6- or A12-desaturase genes were successfully expressed in the transformed F. lipolytica. We examined whether simultaneous expression of A12- and A6-desaturase genes could iucrease the production... 

Laoteng, K., Mannontarat, R., Tanticharoen, M., and Cheevadhanarak, S., A6-Desaturase gene of Mucor rouxii with high similarity to plant A6-desaturase and its heterologous expression in Saccharomyces cerevisiae, Biochem. Biophys. Res. Commun. 2000, 279, 17-22. 

A6-Desaturase Gene Expression. In liver, A6D gene expression (Fig. 4) increased, irrespective of the source of lipids. Oleic acid provided in the diet as the only source of lipids yielded the highest induction of A6D gene expression. LA had a greater effect than ALA on this gene. However, in brain (Fig. 5) and kidney (Fig. 6), A6-desaturase expression did not change, irrespective of the fatty acid provided. 

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