Genetic Modification

Transgenic and cloned animals are often in the news, with the general public concerned about the safety of the food supply and the creation of so-called “franken”-animals. However, the general public has very little understanding of the techniques, processes, results and uses of genetically modified organisms. These process are much too expensive and too difficult to create animals that will go straight into food production, but rather used as breeding stock. Most of the animals created are used for research purposes or for changing the production of the animal into something more beneficial to humans.

Transgenic animals are animals that have had a new, or modified, gene added to their genomes via DNA microinjection. By adding or modifying a gene, these animals can serve an important role in livestock production and in the production of medically important human proteins. A transgenic animal may express more disease resistance or growth than it’s contemporaries, may produce healthier muscle products for human consumption, or may serve as bioreactors in the creation of biomedical products. One example of a transgenic bioreactor, is the creation of transgenic swine that produce important blood clotting factors in their milk. In this case, the  large and complex proteins receive the necessary post-translational modification necessary for their activation in the mammary gland, and can be purified from the milk for human use with no adverse effects to the sow or piglets. Transgenic pigs have also been made which lack the α 1,3-galactosyl cell surface sugar, by using gene-knockout. Since Humans lack the α 1,3-galactosose sugar by knocking out that gene in pigs, which are very similar to humans anatomically and physiology, it may be possible to eventually use pigs as a universal organ donor.

            Once a transgenic animal is created, cloning is a  possible way to maintain the modified genome. Cloning can involve a variety of methods, but the most common is somatic cell nuclear transfer- that is replacing a normal oocyte nucleus with the somatic cell nucleus. A clone is an identical genetic copy of an animal; A clone has the same genome as the somatic cell donor, but the same genes may not necessarily be expressed. Cloning is not only used in maintaining the genetically modified genomes, but may be used to preserve endangered animals, pets, and elite breeding animals. Since cloning creates an identical genomic copy, it reduces genetic diversity, and therefore the viability of endangered species after introducing clones into the population will not increase or may actually be hindered. However, in select cases cloning may be a way to introduce genes that were previously removed from the gene pool. For example, in 2006 the 10-time world champion barrel racing gelding, Scamper, was cloned to produce the stud-colt Clayton. In this manner the gelding’s genes could be used in the population where they previously couldn’t. Geldings or intact males that have been injured and can no longer perform can be cloned and the clone can pass the previously limited genetics along. Cloning is not a guarantee though, that the resultant individual or it’s offspring will produce as well as the original animal due to variations in gene expression and environment.

             The creation of transgenic and cloned animals is an evolving technology with a large amount of potential in the future. By producing clotting factors, universal organ donors, and other biomedical necessities through transgenic and cloned animals allows for a cheaper, and more available resource of products which must otherwise be extracted in a difficult manner. It is imperative, however that the population understands what occurs in both the production of transgenic and cloned animals, if there is any hope of creating products from these animals that can be widely used and accepted by humans.