Wonder Webs(奇妙的網(wǎng))
    Spider webs are more than homes, and they are ingenious traps. And the world’s best web spinner may be the Golden Orb Weaver spider. The female Orb Weaver spins a web of fibers thin enough to be invisible to insect prey, yet tough enough to snare a flying bird without breaking.
    The secret of the web’s strength? A type of super-resilient silk called dragline. When the female spider is ready to weave the web’s spokes and frame, she uses her legs to draw the airy thread out through a hollow nozzle in her belly. Dragline is not sticky, so the spider can race back and forth along it to spin the web’s trademark spiral.
    Unlike some spiders that weave a new web every day, a Golden Orb Weaver reuses her handiwork until it falls apart, sometimes not for two years. The silky thread is five times stronger than steel by weight and absorbs the force of an impact three times better than Kevlar, a high-strength human-made material used in bullet-proof vests. And thanks to its high tensile strength, or the ability to resist breaking under the pulling force called tension, a single strand can stretch up to 40 percent longer than its original length and snap back as well as new. No human-made fiber even comes close.
    It is no wonder manufacturers are clamoring for spider silk. In the consumer pipeline: high-performance fabrics for athletes and stockings that never run. Think parachute cords and suspension bridge cables. A steady supply of spider silk would be worth billions of dollars – but how to produce it? Harvesting silk on spider farms does not work because the territorial arthropods have a tendency to devour their neighbors.
    Now, scientists at the biotechnology company Nexia are spinning artificial silk modeled after Golden Orb dragline. The first step: extract silk-making genes from the spiders. Next, implant the genes into goat egg cells. The nanny goats that grow from the eggs secrete dragline silk proteins in their milk. “The young goats pass on the silk-making gene without any help from us,” says Nexia president Jeffrey Turner. Nexia is still perfecting the spinning process, but they hope artificial spider silk will soon be snagging customers as fast as the real thing snags bugs.
    奇妙的網(wǎng)
    蜘蛛網(wǎng)對蜘蛛來說不僅僅是家，它們還是奇妙的引蟲入網(wǎng)的陷阱。世界昀棒的織網(wǎng)者可能是 Golden Orb Weaver的蜘蛛。雌性的 Orb Weaver可以織出很細(xì)的絲，連被捕的昆蟲都看不見，但卻是堅(jiān)韌得可以將一只飛入網(wǎng)中的鳥纏住而不弄斷。
    那么蜘妹網(wǎng)為何有如此強(qiáng)的力度呢?有一種網(wǎng)絲有超強(qiáng)的彈力，叫做蜘蛛的避敵絲。當(dāng)雄性的蜘蛛準(zhǔn)備編織蛛網(wǎng)的幅條和框架時(shí)，它就用腿從它腹部一個(gè)中空的噴嘴里勾出輕飄飄的絲線。避敵絲不粘，因此蜘蛛可以沿著它來回活動(dòng)編織，從而來編織網(wǎng)的標(biāo)志性螺旋。
    與某些種類的蜘蛛不同，它不用每天織新網(wǎng)，只要網(wǎng)不破，就能一直用下去，有時(shí)一用就兩年。柔軟如絲的蛛絲的強(qiáng)度是相同重量的鋼絲的五倍。同時(shí)可以承受的力度是一種高強(qiáng)度的防彈衣的人工材料的三倍。同時(shí)由于它有很強(qiáng)的抗張強(qiáng)度，即一種能夠抵住被弄斷的拉力，一根單線可以伸長至比原始長度長 40%以上，然后重新彈回至原來的長度，還像新的一樣。沒有一種人造纖維可以與它相媲美。
    因此，生產(chǎn)者們強(qiáng)烈要求蛛絲也就不足為奇了。在消費(fèi)者這一方面，人們強(qiáng)烈要求的是高質(zhì)量的運(yùn)動(dòng)服和永不脫絲的長補(bǔ)襪，試想一下降落傘的繩索和吊橋上的纜線。如果有穩(wěn)定的蛛絲的供應(yīng)，它將是一個(gè)價(jià)值數(shù)十億美元的產(chǎn)業(yè)，但問題是怎么樣才能生產(chǎn)出穩(wěn)定的蛛絲呢?試圖以養(yǎng)蛛場收獲蛛絲是行不通的，這種節(jié)肢動(dòng)物有保護(hù)自己領(lǐng)地的意識，可能會吞掉它們的“鄰居”。
    現(xiàn)在，生物工藝公司“ Nexia”的科學(xué)家們正在研制一種仿制 Golden Orb避敵絲的人工絲。第一步是：從蜘蛛身上抽取制絲的基因，然后，將這些基因植入山羊的卵細(xì)胞中。由這些卵細(xì)胞發(fā)育生的雌山羊會在羊奶中分泌一種帶絲的蛋白質(zhì)。“ Nexia”公司總裁吉弗利•特納說：“這些幼山羊不需我們的任何幫助就可以將制絲基因遺傳過去。”“ Nexia”繼續(xù)在完善它的制絲過程，但是他們希望這種人造蜘蛛絲能盡快地吸引顧客，就像真正的蛛絲抓住小蟲子一樣。