Biologists Crack Genetic Code for Specialized Spider Silk

[C1ay]

Two biologists at the University of California, Riverside, have uncovered the molecular structure of the gene for the protein that female spiders use to make their silken egg cases. The discovery will help biotechnologists develop applications for spider silk and will shed light on spider evolution.

 

lefthttp://hypography.com/gallery/files/9/9/8/lactrodectus_thumb.jpg[/img]Assistant Professor of Biology Cheryl Hayashi and postdoctoral researcher Jessica Garb characterized the variants of the protein (TuSp1) used by 12 species of spiders to make egg-case silk. They found strong similarities in the lengthy amino acid sequences of the proteins among species that diverged at least 125 million years ago.

 

Garb and Hayashi published their findings in the Aug. 1 Early Edition of the Proceedings of the National Academies of Science. Their paper is titled Modular Evolution of Egg Case Silk Genes Across Orb-Weaving Spider Superfamilies.

 

The findings are important, in part, because the mechanical properties of the various types of spider silk " their elasticity, tensile and breaking strength " are dependent on the sequence of amino acids that form the silk proteins.

 

"Collectively, spider silks are some of the toughest natural fibers known," Hayashi said. "Imagine a fabric made from such a substance? It would be incredibly strong, flexible and ultimately, biodegradable."

 

Spider silks have just begun to be considered in the improvement of a wide variety of products such as super-strong body armor, specialty rope, and surgical microsutures.

 

Spiders use silk to move, trap and store food, and to reproduce. Different proteins are made and mixed in silk glands, creating a silk suited to each task. For instance, web-weaving spiders use dragline silk, which is very strong, as a frame for their wagon-wheel-like webs and a different type of silk, known as capture silk, to fill in the web. Capture silk is more elastic than the dragline variety, and is sticky to entrap prey. Of the seven types of silk spiders produce, the fibers used to encase spider eggs are of exceptional strength and durability.

 

"The protein of the egg-case fibers has a different function altogether from that of the other silks such as dragline or capture silks," Garb said. "Egg-case silk has to last a long time and therefore must be durable under a wide variety of conditions, from freezing to very high temperatures. It needs to be strong enough to protect the eggs from threats such as predators, parasites and molds."

 

Despite all this, the molecular sequences of the genes that encode spider silks are only partially known. Garb and Hayashi suggest there are many more spider silk genes waiting to be found.

 

Spider silk genes are composed of long repeating sequences, or modules, and a mutation in one repeat can be spread to adjacent repeats, an example of concerted evolution. Cracking the molecular structure for silk is important not only for the development of products but for those like Hayashi and Garb who study the evolutionary biology of spiders.

 

"The egg-case silk is the product of millions of years of evolution and the amino acid modules can serve as a biochemical blueprint," Hayashi said. Comparison with 25 other spider silk genes showed few similarities, implying that the protein TuSp1 arose by gene duplication followed by substantial sequence evolution.

 

Source: University of California, Riverside

[alxian]

excellent

 

millions of years of evolution yeilding natural materials soon to be taken for granted.

 

 

in factories we create and spin "biosteel" toughened (perhaps with carbon nanostrutures, balls and tubes) and biodegradable under special circustances better for the environment that a diesel powered 800 lb iron ball swinging mechanical monstrocity. cities could be grown and reformed cheaply and without as much fuss when tearing down buildings or roads, just melt them with nontoxic chemicals artificially aging the tough materials reducing them to there chemical constituants.

 

bonus, as tough as the spider silk materials will be they will be lighter. bullet proof armour and other wearables (replacing nylon lycras etc through different weaving techniques) would be lighter and better for the environment.

[CraigD]

This article brings to mind what I recall being one of the most bizarre images of real biotechnology I’d yet encountered, something that might have been culled from William Gibson’s “too weird” stack of discarded cyberpunk story drafts.

 

I read, in Scientific American’s 12/2002 “50 technology leaders” special issue, that a couple of researchers, ANTHOULA LAZARIS and COSTAS KARATZAS, at Canadian company “Nexia Biotechnologies”, had spliced spider genes into hamsters, cows, and, ultimately, “Nexia’s patented breed of fast-growing, early-lactating goats”, and were extracting short filaments of spider silk from the beasties’ milk. Their major customer/partner appeared to be the US DOD, which hoped to mass-produce bulletproof armor from the milk of great herds. :) They came up with the catchy brand name “BioSteelR” for this product.

 

Early difficulties were that the silk fibers were too short for manufacturing, and undesirably stretchier than natural spider dragline silk.

 

The lack of press releases later than 2002, and the news that Nexia sold (for a 10% interest in the company) all of its assets to Maryland’s PharmAthene, Inc, a company know for drugs to treat the effects of biological weapons, not bulletproof-lactating goats, leads me to suspect the last few years efforts to overcome these difficulties may have been less than fully successful.