Tuesday, 22 May 2012

Spider Silk in Transgenic Goats

Spider Silk in Transgenic Goats
The study of genetics has come a long way since Gregor Mendel – the father of genetics. So far in fact that biologists have discovered a method of harvesting spider’s web from goats!

The web of Nephila clavipes (golden orb web spider) could provide countless viable uses in society due to the incredible tensile strength it possess, the highest of class  (Philips, 2011). The problem scientists face however is the solitary temperament of the individual spiders, forcing out the option of farming (Farquhar, 2010 ). To combat this, a genetic study was conducted into the web making genes of Nephila clavipes as well as parallel studies in other organisms in hope to produce large quantities of silk. Molecular biologist Randy Lewis’ breakthrough discovery was that the genes used to create the web are similar to those used by goats in producing milk thus suggesting a possible genetic modification to goats in aim to extract the specific web protein from the goat’s milk. DNA from the spider was inserted into that of the goat ultimately allowing silk to be extracted from the goat’s milk through processing a particular protein responsible for web making (Black, 2000).
From extensive testing of the spider’s silk composition, it was found that the strongest variation of the six that the spider was capable of was the dragline, used for outer structural support of the web (Zyga, 2010 ). From this the specialised dragline silk genes used to generate this portion of the web known as MaSpI were spliced into the embryos of goats allowing cellular division to take place and spread the gene throughout the new born (Lazaris, 2002). The kid, known as a transgenic goat, displayed absolutely no physiological or psychological defects once mature, the only abnormality that the spider genes produced was an additional protein (rc dragline protein) contained within the produced milk (Zyga, 2010 ). This protein consequently can be harvested and purified chromatographically and once dried, rolled into silk.
Despite successful extraction it is imperative to note that the harvested silk isnt up to the standard of natural orb web’s silk in terms of strength and elasticity due to lower concentrations of the rc protein (Gandhi, 2006). As the generations of goats have progressed since the early 2000s however, an increasing concentration of the substance is being harvested from each individual implying that as the MaSpl gene gets passed further down through the generations of transgenic goats, the quality of harvested silk will improve (Zyga, 2010 ). With a reliable amount of quality spider’s silk available, the benefits on society are almost endless. The employers of Randy Lewis – Nexia Biotechnologies aim to commercially sell the silk as ‘biosteel’ due to it’s unrivalled properties. Practical uses of biosteel include bulletproof armor, fishing line, aircraft materials but most importantly for medical use (Black, 2000). One of which is tissue engineering where the biodegradable fibres are used as ‘scaffolding’ for repair in damaged tissues similar to stitches without the removal process (Gandhi, 2006). Specifics within the field of tissue engineering also include eye, ligament, tendon and jaw repair, all of which identified as an ‘area of national importance’ (Gandhi, 2006).
As the transgenic goat generations pass, the quality of silk and undoubtedly the technology used to exploit it will drastically improve, seeing this topic as a key advance in genetics. With such biotechnologies as only representing the origin of genetic advances, the future of genetics is definitely looking bright and open to exploration.

Bibliography

Black, R. (2000, August 21 ). GM goat spins web based future. Retrieved March 20, 2012, from BBC: http://news.bbc.co.uk/2/hi/science/nature/889951.stm
Farquhar, P. (2010 , May 17). Meet Spider Goat . Retrieved March 20, 2012, from News: http://www.news.com.au/technology/sci-tech/meet-spider-goat-the-dna-enhanced-web-flinging-nanny-that-may-one-day-knit-your-bones/story-fn5fsgyc-1225867617374
Gandhi, M. R. (2006). Silk Protein as a Biomaterial for Tissue Engineering Application. Philadelphia : Drexal University.
Lazaris, A. (2002, January 18). Spider Silk Fibers Spun from Soluble Recombinant Silk Produced in Mammalian Cells. Retrieved March 20, 2012, from ScienceMag: http://www.sciencemag.org/content/295/5554/472
Philips, C. (2011, November 23). Golden orb web spider spins ant-repellent silk. Retrieved March 20, 2012, from Australian Geographic: http://www.australiangeographic.com.au/journal/golden-orb-web-spider-spins-ant-repellent-silk.htm
Zyga, L. (2010 , May 31). Scientists breed goats that produce spider silk. Retrieved March 20, 2012, from Physorg: http://www.physorg.com/news194539934.html

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