flickr, meneer zjeroanTwo unsuspecting farm animals have helped to demonstrate the increasing accuracy of genetic engineering techniques. The first is a cow that produced hypoallergenic milk after researchers used RNA interference to block the production of an allergy-inducing protein, as reported today (October 2) in PNAS. The second, reported in another paper in the same issue, is a pig that could be a model for atherosclerosis after researchers used an enzyme called TALEN to silence a gene that usually helps to remove cholesterol.
Researchers have long struggled to remove cow milk's allergy-inducing protein, beta-lactoglobulin, which can cause diarrhoea and vomiting in children. They were previously unable to introduce foreign genes precisely enough, however, so they could never quite successfully replace the gene that codes for beta-lactoglobulin with a defective form.
But scientists at AgResearch in Hamilton, New Zealand, worked with molecules that interfere with messenger RNA (mRNA), which helps translate genes into proteins. They found microRNA (miRNA) in mice that targeted beta-lactoglobulin mRNA, so they inserted DNA encoding a version of this miRNA into the genomes of cow embryos. Out of 100 embryos, one calf produced beta-globulin-free milk. “This isn’t a quick process,” Stefan Wagner, a molecular biologist at AgResearch, told Nature. One problem is that RNA interference ...
