OVER-EXPRESSION OF GENE ENCODING FATTY ACID METABOLIC ENZYMES IN FISH
Abstract: Eicosapentaenoic
acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) have important
nutritional benefits in humans. EPA and DHA are mainly derived from fish, but
the decline in the stocks of major marine capture fishes could result in these
fatty acids being consumed less. Farmed fish could serve as promising sources
of EPA and DHA, but they need these fatty acids in their diets. Generation of
fish strains that are capable of synthesizing enough amounts of EPA/DHA from
the conversion of α-linolenic acid (LNA, 18:3n-3) rich oils can supply a new
EPA/DHA source. This may be achieved by over-expression of genes encoding
enzymes involved in HUFA biosynthesis. In aquaculture, the successful of this
technique would open the possibility to reduce the enrichment of live food with
fish oils for marine fish larvae, and to completely substitute fish oils with
plant oils without reducing the quality of flesh in terms of EPA and DHA
contents. Here, three genes, i.e. Δ6-desaturase-like (OmΔ6FAD),
Δ5-desaturase-like (OmΔ5FAD) and elongase-like (MELO) encoding EPA/DHA
metabolic enzymes derived from masu salmon (Oncorhynchus masou) were
individually transferred into zebrafish (Danio rerio) as a model to increase
its ability for synthesizing EPA and DHA. Fatty acid analysis showed that EPA
content in whole body of the second transgenic fish generation over-expressing
OmΔ6FAD gene was 1.4 fold and that of DHA was 2.1 fold higher (P<0.05) than
those in non-transgenic fish. The EPA content in whole body of transgenic fish
over-expressing OmΔ5FAD gene was 1.21-fold, and that of DHA was 1.24-fold higher
(P<0.05) than those in nontransgenic fish. The same patterns were obtained
in transgenic fish over-expressing MELO gene. EPA content was increased by
1.30-fold and DHA content by 1.33-fold higher (P<0.05) than those in
non-transgenic fish. The results of studies demonstrated that fatty acid
content of fish can be enhanced by over-expressing gene encoding enzymes
involved in fatty acid biosynthesis, and perhaps this could be applied to
tailor farmed fish as even better sources of valuable human food.
Keywords: expression; gene;
fatty acid; biosynthesis; fish
Author: Alimuddin, Goro
Yoshizaki, Toshio Takeuchi, Odang Carman
Journal Code: jpperikanangg080010
