在线英语听力室_免费在线英语听力学习网站

What’s five times as strong as steel, twice as tough as Kevlar, and can be stretched over thirty percent in length without breaking? The answer is spider silk.
什么东西的强度是钢的5倍？什么东西的韧性是凯夫拉的2倍？什么东西能够拉长到自身长度的30%却不会断裂？答案是，蜘蛛丝。

Spiders make at least six different types of silk which they use for locomotion¹, protecting eggs, wrapping prey², and gluing pieces of web together. Silk is not only strong, it’s biodegradable and produced at low temperatures and pressures, unlike many man made polymer fibers³.
蜘蛛能生产至少6种不同类型的蛛丝用以移动、护卵、捕食和结网。蛛丝不仅结实，而且在低温低压下可生物降解和再生。这有别于许多人造纤维。

Why don’t we use spider silk to make things?
为什么我们不利用蜘蛛丝来制作产品呢？

Unlike silk worms, spiders can’t produce much silk at a time. It took eighty weavers⁵ and a million golden orb⁶ spiders five years to make a spider silk rug a little over twelve feet square.
蜘蛛无法像蚕那样在短时间内产生大量的丝。制作12平方英尺多点的蛛网地毯，需要80名织工，使用100万只金球蜘蛛，花费5年时间才能完成。

Scientists decided⁷ to work on the silk quantity problem. And, no, they didn’t create giant spiders. First, they identified soft and crystalline components⁸ in the silk protein sequences that make it both stretchy and strong. Once they identified these elements, they located the gene⁹ that codes for spider silk.
科学家们决定研究蛛丝的数量问题。当然他们不会去创造巨型蜘蛛。首先，他们在蛛网蛋白序列中识别出使蛛网具备延展性和强韧性的柔软又透明的成份。一旦科学家们成功识别出这些成份，他们就能锁定形成蛛网的基因。

Genes¹⁰
基因

With the gene in hand, scientists decided to use a common intestinal¹¹ bacteria named Escherichia coli to help them. They inserted the spider gene into the bacteria. Because the protein was large, they had to do some metabolic¹² engineering to enable the bacteria to produce it.
基因到手后，科学家们决定使用一种普遍的肠道细菌——大肠杆菌——作为辅助。他们要把蜘蛛基因嵌入大肠杆菌。不过蜘蛛的蛋白很大，所以科学家们需要做一些代谢工程使得大肠杆菌能够生产蜘蛛蛋白。

In the end, they made spider silk, but it wasn’t as fine as the real thing. That’s because spiders enhance the uniformity of their silk as they pull it from their spinnerets.
最后，大肠杆菌产出蛛网，但其质量不如真正的蛛丝那么理想。原因在于蜘蛛是从吐丝器官里把蛛丝拉出来的，这加强了蛛丝的均匀性。

The pulling process wasn’t replicated¹³ in the lab until scientists developed a device to mimic¹⁴ the fiber⁴-pulling step. They have now created a thread rivaling natural silk.
在科学家们开发出一种模拟拉出蛛丝的设备之前，这种拉丝过程无法在实验室里复制。不过科学家们现已创造出一种与织线媲美的天然丝。

This great fiber could soon be used for violin strings¹⁵ as well as bullet proof vests.
这种优质的纤维预计很快就能用于小提琴琴弦或者防弹背心上了。