Utah State University’s Synthetic Spider Silk Laboratory is using CRISPR technology to edit the DNA of silkworms in order to increase the strength and elasticity of their silk. Their DNA will contain strands from silk spiders, who are known for their incredibly strong silk.
Because spiders only produce small amounts of this super-strong silk, it is difficult to utilize the material for commercial and engineering applications. Randy Lewis, former director of the Spider Silk Labratory, has been interested in mass producing this material by inserting the spider’s gene that produces the silk proteins into the DNA of other organisms.
Using CRISPR technology, scientists at the Spider Silk Lab were able to precisely insert the spider silk gene into silkworms, allowing these caterpillars to produce silk with comparable strength and elasticity to natural spider silk. CRISPR is shorthand for a DNA editing technology where enzymes act as molecular scissors, selectively cutting strands of DNA.
Prior to CRISPR, the silk genes were randomly inserted into the silkworms’ DNA, Lewis said. Using CRISPR, they can now precisely insert genes into specific locations in the silkworm’s genome.
“We chose two places, both of which are genes that the silkworms use to make proteins for its own cocoon, we were able to very precisely cut out the large gene and insert ours exactly in the same spot. The silkworm does not recognize that as a foreign gene and goes ahead and uses it to make its cocoon,” said Lewis.
Because the genes are now successfully assimilated into the silkworm DNA, Lewis said the silkworms are able to pass the silk protein gene onto its offspring.
“By selective breeding, we can pick the best producers of proteins and mate those, so we actually see mechanical properties improve after each generation,” said Lewis
Lewis said each silkworm cocoon produces about 600-1000 meters of double fiber silk. They are currently working with a company in China interested in taking the next steps to commercialize this product.