By Elijah Chia
Image from (BMC Cancer, 2012)
Transgenic animals, simply put, are genetically modified animals that contain a mix of both their own genetic material, along with genes from another species or breed. While accomplishing such feats may seem futuristic, transgenic animals have been around for a long time — the first ever transgenic animal being a mouse mixed with fruit fly genes in 1974 by Rudolf Jaenisch. Ultimately, this first breakthrough was pivotal in providing scientists with a form of studying how genes affect organisms. Today, transgenic animals are important for helping researchers and scientists find new treatments or cures for human diseases. They also have the potential to improve animal welfare within the livestock industry, preventing highly contagious diseases amongst livestock to be eradicated through new resistant genes.
While the method for producing transgenic animals has changed over time, new developments in the relevant technology have allowed the process to become more efficient and refined. To iterate, a goat and a spider can result in a transgenic goat that produces spider silk instead of regular goat milk. Spider silk generally has extremely high tensile strength, and due to its flexible yet durable properties, it is used in artificial ligaments, or to make extremely strong materials. However, seeing as spiders are a highly cannibalistic species, and will actively kill one another, producing large quantities of spider silk has proved challenging in many ways, hence why silk-producing goats are used.
The process starts with the specific ‘silk-producing gene’ found in the spider being extracted using restriction enzymes — an enzyme produced by certain bacteria which have the ability to effectively ‘cut’ a sequence of DNA. Next, the somatic cell of one goat (let's refer to it as Goat A) is removed and then enucleated. A somatic cell is any other cell in the body apart from sex cells (i.e. sperm and egg cells), while the term enucleated simply means to remove the nucleus or the cell’s genetic material. Following this, with the nucleus of the somatic cell belonging to goat A, the spider silk gene is then introduced via ligase — an enzyme that essentially helps to bond the DNA together. From here, an egg cell from a second goat (Goat B) is extracted and enucleated. Next, the transgenic nucleus (nucleus with spider silk gene) is inserted into the empty egg cell, where it then develops into a zygote, which then divides into an embryo. Finally, this embryo is implanted surgically into a third goat (Goat C), where it is used merely as a surrogate mother, eventually giving birth to a new goat (Goat D) with the spider silk-producing genes incorporated inside of it. As a result, instead of producing goat's milk, it instead produces spider silk.
To conclude, the investigation into the world of transgenic animals has benefited humanity greatly in numerous different industries. While the widespread application of transgenic animals can come with a variety of benefits, there are numerous ethical concerns arising over the fact that not enough research has been conducted to guarantee the success of a transgenic animal — there can be unknown side effects, genetic mutations, or errors within the process itself. Furthermore, many view this as tampering with the natural order or world, exploiting it for the sole purpose of human gain. While the world of genetic engineering is certainly here to stay, can we say the same about transgenic animals?
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