Japanese researchers have announced that they succeeded in transplanting a spinach gene into a pig in order to change pig fat into linoleic acid, a principal unsaturated fatty acid found in plants and considered essential to animal nutrition.

It is the first time in the world that a plant gene has been made to function properly in a mammal, the group led by Akira Iritani, professor at the School of Biology-Oriented Science and Technology at Osaka-based Kinki University, said Tuesday.

Iritani, an expert in embryology engineering, said his group will now be able to apply the new technique to producing genetically modified foods and investigate the safety of using modified pigs as food products.

Iritani and Norio Murata, professor at the National Institute for Basic Biology in Okazaki, Aichi Prefecture, and YS New Technology Institute, Inc., a venture company in genetic engineering in Tochigi Prefecture, jointly conducted the study.

The researchers directly implanted a gene called FAD2 into fertilized pig eggs and implanted them into the womb of a surrogate mother pig that gave birth to piglets with the modified gene.

The genetically modified pigs had about a 20 percent higher linoleic acid rate in their fat than normal pigs. They were healthy and had normal reproductive capacities and were confirmed to carry the same trait to the third generation. FAD2 is an enzyme that changes oleic acid, another unsaturated fatty acid, into linoleic acid, which is necessary for normal growth of mammals.

The enzyme is contained in plants such as spinach, but mammals, including humans, have to intake it from food as they do not carry it.

The group has also succeeded in increasing linoleic acid in mice by 40 percent and is aiming at producing pigs with more linoleic acid as well as implanting other essential fatty acid in pigs.