Hot Topic: Using a Stearoyl-CoA Desaturase Transgene to Alter Milk Fatty Acid Composition

Abstract

Stearoyl-CoA desaturase enzyme converts specific medium- and long-chain saturated fatty acids to their monounsaturated form. Transgenic goats expressing a bovine beta-lactoglobulin promoter-rat stearoyl-CoA desaturase cDNA construct in mammary gland epithelial cells were produced by pronuclear microinjection. The fatty acid composition of milk from 4 female transgenic founders was analyzed on d 7, 14, and 30 of their first lactation. In 2 animals, the expression of the transgene changed the overall fatty acid composition of the resulting milk fat to a less saturated and more monounsaturated fatty acid profile at d 7 of lactation; however, this effect diminished by d 30. In addition, one animal had an increased proportion of the rumen-derived monounsaturated fatty acid C18:1 trans11 converted by stearoyl-CoA desaturase to the conjugated linoleic acid isomer C18:2 cis9 trans11. Milk that has higher proportions of monounsaturated fatty acids and conjugated linoleic acid may have benefits for human cardiovascular health.

Genetic variability of milk fatty acids

“…1.14.19.1), catalyses the introduction of a cis-double bond between carbons 9 and 10 of SFAs with a chain length of 10-18 carbons Thomson et al 2003). So, it converts specific medium-and long-chain SFAs into the corresponding MUFAs (Reh et al 2004). This last activity is an essential step in the synthesis of unsaturated FAs.…”

The use of genetic engineering techniques to improve the lipid composition in meat, milk and fish products: a review

“…Thus, the milk fat of transgenic goats expressing the SCD rat gene in the mammary gland contained decreased concentrations of SFAs, while levels of MUFAs and CLAs rose. Thus, as indicated by the authors, such milk may have benefits for human cardiovascular health (Reh et al, 2004). The results of an in vitro study by Wu et al (2010) showed that the foreign SCD1 transgene could be expressed in transformed mammalian cell lines with high efficiency and induced elevated CLA isomers and n-7 MUFA (palmitoleic and cis-vaccenic acid) levels in mammalian cells.…”

“…In experimental conditions, goats, due to their small size and short reproductive cycle, are relatively cheap and convenient objects of biotechnological studies whose results can be used successfully as a model for dairy cows. Reh et al (2004) created transgenic goats expressing a rat stearoyl-CoA desaturase (SCD) gene in the epithelial cells of the mammary gland. The SCD enzyme catalyses the formation of double bonds between 9 and 10 carbon atoms of certain SFAs, and therefore is responsible for the conversion of these acids to MUFAs.…”

The Welfare of Transgenic Farm Animals

“…Under consideration are cows that produce milk with fewer disease-causing components -fewer allergens, less lactose, or less saturated butterfat, though the industry fears the latter could deleteriously impair the whipping of cream (Gibson, 1991;Jost et al, 1999;Karatzas & Turner, 1997;Reh et al, 2004). Adding human breast milk genes to dairy cow udders has been suggested to improve baby formula (Wall et al, 1997).…”