840.119:Biosteel

Project Description

For the past four years, since Nexia Biotechnologies sold their company, not much has been done in the area of transgenic goats and spider silk. The first group of scientists to successfully obtain silk from goat's milk was done by Lazaris, et al, 2002. The project was successful in obtaining spider silk, but not enough to spin into a fiber. In the future, if scientists are successful in obtaining enough with the same strength as a natural spider web, the possibilities for its use would be limitless. In the experiment done by these scientists in 2002, they started out with the spider silk gene, and then placed that gene into the egg of a goat. Once the goat grew to an adult, it was cabable of producing silk within it's milk.

State of the Art

Why is this needed?

This product could potentially be used for artificial tendons, and limbs; tissue repair; sutures for eye or neurosurgery. Using this product could potentially save hundreds of lives. Because spider silk is biodegradable, this product could replace plastic bottles and nylon to make these products safer for the environment. Since silk is lighter than many synthetic fibers, it could potentially be used for aircraft, cars, and bullet proof vests.

Spider Silk

Over 400 million years of evolution has perfected this amazing fiber. The silk has to be both durable and invisible to prey to be successful. First the spider secretes a protein solution, as the silk dries, it becomes taut, forming an insoluble thread.

Objectives

Advantages of using Biotechnology

Biotechnology methods make the process of producing large quantities of silk without a large amount of spiders. It would be very difficult to have a spider farm. It is more efficient and cost effective to use goats, then to have numerous amounts of spiders.

Scientific Approach

Nexia Biotechnologies in Canada were the first to discover what would happen when a spider gene was crossed with a goat's gene. Because the both the spider and goat glands are similar, they were able to inject the gene into an unfertilized egg. When the female goat goes through lactation, the spider gene will turn on and then turn off when the female is done lactating. In one day, the goat can produce 1.5 liters.

Methods

Transgenesis is the placement of one gene into another organism of another species. The process is similar to cloning of Dolly the sheep. First, unfertilized eggs have their nuclei removed. Second, cells are taken from one goat and transferred into the unfertilized eggs. These cells contain nuclei that replace the existing nuclei of the unfertilized egg. Third, the cells are allowed to culture. Finally, the cells are placed into a parent goat, where the fertilized egg will grow into a normal, spider silk producing goat.

Alternative Methods

Other methods of obtaining the dragline silk, includes using recombinant DNA technology in plants, specifically the tobacco leaves and potato tubers. Up to 2% of the total soluble protein in these plants endoplasmic reticulum is found to be the dragline silk transgenic product. The silk can be obtained from these plants through extreme heat purification, due to the large stability of the silk products. Problems with this method include producing manufacturable products from the purified silk intermediate. (1)

Attempts with yeast and bacteria were also tried. However, the size of the silk produced was too large for the yeast and bacateria to house, due to their small size. (2) Due to the repetitive nature as well as the unusual mRNA secondary structure, there was inefficient translation, thus limited size of the produced silk proteins.(?)

Impacts

With enough silk fibers, a fabric could be produced that would be five to even 20 times stronger than steel, biodegradable, and extremely lightweight for its strength. The material could be used to produce flak jackets beyond the strength of current kevlar, and biodegradable products including sutures. The use of this product along with the science behind its high tensile strength and low weight, would create huge advancements in cable/rope strength, that would be used for anything from "space-age architecture" to air and space craft.

Associated Risks

Currently there are no known problems with using trandgenesis in goats. The goats that are born are like any other healthy goats, except that they produce silk within their milk.

References

Scientific articles

Lazaris et al., 2002-01-18. Science. Vol. 295:472-476

Weblinks

http://www.eurekalert.org/pub_releases/2002-01.nbi-nau011102.php

http://www.howstuffworks.com/news-item38.htm

http://arachnophiliac.co.uk/burrow/news/spinning_steel.htm

http://www.moaa.org/magazine/January2003/f_superwarriors.asp

http://www.spacedaily.com/news/materials-02a.html