The genetic secrets of the black widow spider
Biologists at the University of California at Riverside (UCR) have identified the genes for two key proteins in the 'dragline silk' of the black widow spider. This silk, one of the seven different silks that an individual spider produces, is used by spiders as the structural foundation of their webs. But the one created by the black widow spider has outstanding strength and extensibility properties. The identification of its genetic secrets could lead to synthetic new materials for military uses, such as lightweight super-strong body armor, or for high-tech athletic gear.
You can see on the left a photo of a female black widow spider (Latrodectus hesperus) with her dragline silk (Credit: Mark Chappell, UCR; link to a larger version). This research on the genes of the black widow spider has been led by Cheryl Hayashi, Associate Professor of Biology, and postdoctoral researchers Nadia Ayoub and Jessica Garb.
Now, let's go back to the UCR news release to learn more about how this research project could lead to new synthetic materials.
There are currently no products on the market based on the dragline silk of spiders. "There's nothing quite as good yet as natural dragline silk, but we should get a lot closer now that we have the full genetic recipe," Hayashi said. With the ingredients and their genetic blueprint now known, it may be possible to synthetically produce the proteins by inserting the genetic sequences into host organisms such as bacteria, plants or animals, she said. Once the pure proteins are harvested, a manufacturing challenge will be spinning them into silk fibers that have the same remarkable properties as spider spun silk. But several advances have recently been made in artificial spinning methods.
For more information, this research work has been published in the June 13 online edition of the journal PLoS ONE under the title "Blueprint for a High-Performance Biomaterial: Full-Length Spider Dragline Silk Genes." Here is a link to this technical paper.
And here are some excerpts from the introduction. "Here we describe the first full-length spider silk gene sequences and their flanking regions. These genes encode the MaSp1 and MaSp2 proteins that compose the black widow's high-performance dragline silk. Each gene includes a single enormous exon (>9000 base pairs) that translates into a highly repetitive polypeptide. Patterns of variation among sequence repeats at the amino acid and nucleotide levels indicate that the interaction of selection, intergenic recombination, and intragenic recombination governs the evolution of these highly unusual, modular proteins. [...] Our new data provide complete templates for synthesis of recombinant silk proteins that significantly improve the degree to which artificial silks mimic natural spider dragline fibers."
So when will we wear clothing made of artificial black widow spider silk? The researchers don't know yet.
Sources: University of California, Riverside, via EurekAlert!, June 12, 2007; and various websites
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