Goats to give Spider Silk
Posted by Unknown in Goat, Milk, Research and Technology, Silk, Zz_Wordpress on Sunday, 9 September 2012
by Will Knight
Spider silk has been grown from genetically modified cells for the first time. The research company behind the feat believes it opens the way for the manufacture of super-strong, light and biodegradable materials within a few years.
Nexia, based in Canada, is also breeding goats that have been genetically modified with spider genes and hopes that their milk will be a plentiful source of the proteins required for spider silk. Nexia says that the modified goats have bred females that are now pregnant themselves, but will not reveal whether these are producing milk or whether it contains the necessary proteins.
In the current research, cells were taken from the mammary glands of dairy cows and genetically modified with spider genes to produce the proteins used to make spider silk. The proteins were then stretched and spun from an aqueous solution into fine silk fibres.
"We're not perfectly mimicking nature, but this shows a major breakthrough that no-one has been able to achieve before," says Jeff Turner, president of Nexia.
David Knight, a research zoologist at Oxford University, says that the new research is impressive: "It is the first time that they have got a pure protein that is soluble, despite being so hydrophobic."
However, he points out that the synthetic silk generated by Nexia was too stretchy to be turned into a practical material. "It extends too much to be used for anything," he says.
Stronger than steel
Knight also suggests that, in order to create a spider silk as good as the natural silk, it may be necessary to combine two different proteins that are used by spiders. A spinning method that better simulates the spider's may also be necessary, he says.
Nexia's "biopolymer" also had only 30 percent of the strength of natural spider silk, but the company believes that this can be increased by refining the spinning process.
Spider silk is one of the strongest and most flexible materials in the natural world, five times stronger than steel by weight. It would be ideal for bullet-proof clothing, biodegradable fishing nets and medical materials, such as sutures. But spiders are too aggressive to be farmed and previous efforts to grow the silk from bacterial cultures have failed.
Nexia bred two male goats modified with spider genes in January 2000. These have since bred with normal goats and transferred the spider silk gene to female offspring, which are now pregnant.
The approach is believed to be promising because the epithelial cells found in goats' mammary glands and those in spider's silk glands produce similar types of complex, water-soluble proteins. It may be possible to mass-produce spider silk in this way within a matter of years, according to Turner.
The work was performed with the help of the US Natick Soldier Center in Massachusetts.
Journal reference: Science (vol 295, p 472)
