Spider Silk? Bring On the Nanny Goats
Spiders look scary and with good reason. They are all predators, you know. Their eight hairy legs and alarming mouth parts would frighten any potential victim. Although the usual victims are insects, even most people are reluctant to get too close to these creatures. Nevertheless, despite their frightening appearance, spiders are actually wonderfully designed organisms. Many species effortlessly produce an amazing product — spider silk. For forty years, scientists working for the American military, have sought to produce something like spider silk. Apparently this material is, by weight, five times stronger than steel. the military would love to use it for bullet proof vests, for parachutes, tents and surgical dressings. Until very recently however, all that the scientists produced was useless blobs. The spider, on the other hand, turns special proteins into as many as seven kinds of silk. The best plan would have been to let the spider do all that for us as well as for herself. Spider farming would have been fine, except that these fierce predators ate each other up. So it was back to the drawing board.
Everyone was optimistic in the early 1990s when two genes for silk were obtained from spider DNA. All that seemed necessary now was a little biotechnology and we would have the desired product. The genes thus were inserted into suitable bacteria. Unfortunately the silk genes were long and the bacterial cells extremely tiny. For whatever reason, the bacteria rejected the inserted genes. Next these genes were tried in yeast cells, but again no useful product was obtained. Chemical companies like du Pont tried to manufacture a synthetic version of the silk based on their knowledge of the molecule structure. But the results were dismal.
Recently a Canadian company, Nexia of Montreal in association with the American military, has announced some progress. This company began its research in 1993. Since the protein molecule is so long (and unusual), Nexia scientists wondered if larger animal cells would be helpful. However they didn’t want to kill animals for just a few grams of silk. That would be way too inefficient (and expensive). The plan was thus devised to use the milk producing glands of special BELE (breed early, lactate early) goats. During December of 2000, Nexia announced plans to transfer a spider silk gene into the mammary glands of these goats. The company had a herd of 1200 of these animals which would, it was hoped, produce commercial quantities of silk by the year 2002. The product would be called BioSteel. Well here we are in the year 2002 and there is still no commercial production of BioSteel.
It was soon discovered that the easiest way to insert the spider silk gene into female goats was through breeding. For a start, the gene (designed to express itself only in active milk glands) was inserted into the reproductive cells of two male goats: Peter and Webster. These animals were then crossed with various female goats. In the spring of 2002, the daughters of Peter and Webster are now pregnant. No silk has as yet been synthesized. However, it is hoped that these goats will produce milk which is liberally laced with the liquid form of spider silk. Nexia does not yet know if the goats will produce enough silk protein or even whether they will be able so spin it into a useful fibre.
To find out if this was a reasonable hope or not, Nexia scientists inserted the same silk gene into cultures of cells from cow milk glands and also baby hamster kidney cells. From these cultures, a tiny quantity of silk was extracted. The really good news for investors in BioSteel was that they managed to spin a few filaments which looked and acted somewhat like silk. The bad news was that it was much less strong than spider silk. If you were wearing a bullet proof vest of this new product, the bullet would go right through you “and stop a metre on the far side”. Clearly more work was needed.
Spider silk continues to baffle and amaze scientists. They were amazed to observe how the proteins, when given the right conditions, simply lined themselves up to produce a fibre. The scientist in charge declared the whole thing was like “magic”. The researchers then had to treat the fibre with baths and stretching to develop the desired spider silk properties. Initially, scientists had hoped that once a suitable protein was obtained, the spinning of suitable fibre would be easy. Alas they soon discovered that this was not the case. They now know that “conditions under which the fibres are spun and processed are critical in determining mechanical properties.” (A. Lazaris et al. 2002. Science 295 #5554 p. 475). In short, spiders know how to produce silk in one easy step and we, after forty years, do not yet know how.
Indeed it is evident that spiders have been created with truly amazing talents. We, for our part, will keep on trying to duplicate their know how. So bring on the nanny goats! Maybe we will obtain spider silk or maybe we won’t. The continuing saga however reinforces our awe of the Creator. Can you imagine that the spider on her own, spontaneously developed special proteins, special spinning technology and behaviour patterns to put the products to good use? Of course not — not even in “hundreds of millions of years.” The evolutionists, quoted in most articles on spider silk, are dreaming.
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