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Spider Goats and Genetic Modification

Spider silk is an extremely useful material, as it is very light, flexible, and incredibly strong. When in an equal diameter, spider silk is stronger than steel, and much more resistant and elastic than rubber and nylon. At the same weight, it is twice as strong as Kevlar. Due to its many qualities, spider silk is used to create a variety of military equipment, such as ropes, nets, parachutes and bullet proof clothing. Shoes can also be created using spider silk, and even artificial tendons and ligaments were crafted using this material. Scientists have tried to farm spiders for their silk, but it has been proven to not be worth it. Spiders simply do not produce large quantities of silk quickly, as it takes 4 years for 1 million spiders and more than 70 workers to gather and manufacture an 11x4 foot piece of fabric made with the silk. Additionally, it is impossible to farm spiders, as they are cannibalistic carnivores, which means that if they were placed in the same space, it would end in complete chaos. Since spider silk is such a useful material, scientists have studied and tested many ways to make the manufacturing of silk practical, which is why researchers from the University of Wyoming have been developing the production of spider goats; genetically modified goats that produce the protein used to make silk in their milk.

In order to genetically modify the goats, scientists need to isolate what is called a gene of interest, which is the gene that they want to incorporate into the goat’s DNA. In this case, the gene of interest is the gene in orb-weaving spiders that allows them to produce dragline silk. Next, a vector, which is a vehicle used to carry genetic material, also needs to be isolated. The vector used is going to be a plasmid of the pBC1 bacteria. Once both the gene of interest and vector are isolated, digestion needs to occur, which is when both the gene of interest and plasmid will be cut at specific sequences of the DNA by restriction enzymes. In such circumstances, the DNA sequence in the vector and gene of interest is going to be cut by TspRI enzymes. After digestion occurs, ligation takes place, which is when the gene of interest is placed in the vector. This is done by DNA ligase, which joins the sugar-phosphate backbones of the gene and vector. In other words, the dragline silk gene, which will code for an extra histidine in the DNA sequence, is placed in the vector by joining their cut ends. The result of this bond is called a recombinant vector. Finally, after ligation, the recombinant vector has to be inserted into the host cell, making the cell transgenic. In this process, the gene delivery is going to take place at the nucleus of an egg cell, between the base pairs of 88 and 700 in the goat’s genome. Since the host cell is eukaryotic, this process is labeled as transfection. The genetically modified nucleus is then extracted from the cell and placed into a fertilized egg cell. The goat with the fertilized egg cell will now have the genetically modified DNA or dragline silk gene, which adds an extra histidine or “His” amino acid to the DNA sequence. Consequently,hen it produces its offsprings, they will be born with the dragline silk gene, which will allow them to produce the silk protein in their milk.


Diagram illustrating how the process of delivering the gene and inserting the genetically modified nucleus into a fertilized egg works:


The major benefit of the spider goats is the time taken to produce silk and the quantity produced each day. When working with spiders, it took years to gather enough silk to be able to manufacture a piece of fabric, however that is not the case with spider goats. Approximately half an ounce of silk is produced in every quart of goat milk. In other words, for every 950 ml of milk, roughly 14 grams of silk are produced. This means that a single goat who is milked for the recommended amount (twice a day) can produce roughly 840 grams of silk per month, keeping in mind that unlike spiders, goats can be farmed in large quantities. A medium sized farm with 12 goats could produce more than 10 kilos monthly. Further, goats are very social animals, who can perfectly live in the company of others. Not only can they live with each other, but with other animals such as cows, horses and donkeys as well. In fact, it is advised that goats should never live alone. Overall, these positive implications are linked with politics, since now that the silk can be produced at a much faster rate, governments are investing in the production of spider goats, aiming to turn the silk into military equipment. In December 2015, the US army paid 1 million dollars for the University of Utah to produce silk for them, and still constantly invest in the research of spider goats.

The biggest negative implications of the spider goats are the ethics and morale involved in the process of genetic modification. Many people believe that genetically modifying a living organism is wrong and should not be done, claiming that it is simply “fundamentally wrong”. Usually, people with strong religious beliefs are the ones that reject the idea of genetically modifying organisms, claiming that it is unethical for it is an attempt to put humans over god, which would be disrespecting his image. Changing the genes of living organisms for those who are religiousis “cheating life” and “playing god”. The Zogby International Poll concluded that most Christians and Muslims are opposed to the transferring of genes from one organism to another. Jews were the religion with the biggest approval, with 55% of them supporting genetic modifications.


Spider goats may not be supported by everyone, but they do display advancements in science and biotechnology, which signals that a future with heavy genetic modification is up ahead. Things that once seemed like plots of sci-fi movies like changing traits of offsprings, curing syndromes before babies are born, and handpicking looks are on track to become reality.


Bibliography:


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Rutherford, Adam. “Synthetic Biology and the Rise of the 'Spider-Goats'.” ​The Guardian​, Guardian News and Media, 14 Jan. 2012, www.theguardian.com/science/2012/jan/14/synthetic-biology-spider-goat-genetics​.

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Tokareva, Olena, et al. “Recombinant DNA Production of Spider Silk Proteins.” ​Microbial Biotechnology,​ Blackwell Publishing Ltd, Nov. 2013, www.ncbi.nlm.nih.gov/pmc/articles/PMC3815454/​.

Zyga, Lisa. “Scientists Breed Goats That Produce Spider Silk.” ​Phys.org​, Phys.org, 31 May 2010, phys.org/news/2010-05-scientists-goats-spider-silk.html.

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