The race to sequence the human genome - Tien Nguyen

翻译人员: Aiting Ye 校对人员: Yolanda Zhang

Packed inside every cell in your body is a set of genetic instructions,

我们身体每一个细胞里都有一组

3.2 billion base pairs long.

长达32亿组碱基对的遗传指令。

Deciphering these directions would be a monumental task

要解读这些指令是一项无比艰巨的任务，

but could offer unprecedented insight about the human body.

但对我们了解自身有着深远的意义。

In 1990, a consortium of 20 international research centers

1990年，由20个国际研究中心组成的

embarked on the world's largest biological collaboration

合作团队开始着手完成

to accomplish this mission.

这项全世界最浩大的生物工程。

The Human Genome Project proposed to sequence the entire human genome

人类基因组项目预测这项基因测序工程

over 15 years with $3 billion of public funds.

需要长达15年的时间，耗资30亿美元。

Then, seven years before its scheduled completion,

然而，在项目预计完成的7年前，

a private company called Celera announced that they could accomplish the same goal

一个叫做Celera的私人企业宣布

in just three years and at a fraction of the cost.

他们可以用更少的资金， 在三年内就完成这一项目。

The two camps discussed a joint venture, but talks quickly fell apart

这两个团队曾试图展开合作， 但是谈判最终因为

as disagreements arose over legal and ethical issues of genetic property.

对研究结果 在法律和伦理上的分歧而失败。

And so the race began.

于是他们之间的竞争开始了。

Though both teams used the same technology to sequence the entire human genome,

尽管两个团队在基因测序方面 采用了同样的技术手段，

it was their strategies that made all the difference.

他们测序的策略却截然不同。

Their paths diverged in the most critical of steps:

区别就在于以下关键几步：

the first one.

首先，

In the Human Genome Project's approach,

人类基因组计划的方案是

the genome was first divided into smaller, more manageable chunks

把整个基因图谱分为更小， 更易操作的片段，

about 150,000 base pairs long

每个片段都由15万个碱基对组成，

that overlapped each other a little bit on both ends.

相邻片段首尾均存在小部分重叠。

Each of these fragments of DNA

每个DNA片段都被注入到

was inserted inside a bacterial artificial chromosome

人工培育的细菌染色体中，

where they were cloned and fingerprinted.

并被复制，从而获得指纹谱图。

The fingerprints showed scientists where the fragments overlapped

指纹图谱可以向科学家们展现

without knowing the actual sequence.

那些未知序列中的重叠部分。

Using the overlapping bits as a guide,

利用这些重叠的小片段作为线索，

the researchers marked each fragment's place in the genome

研究者们在染色体中对各个片段做记号，

to create a contiguous map,

以获得一幅延续性的图谱，

a process that took about six years.

这个过程持续了六年之久。

The cloned fragments were sequenced in labs around the world

全世界所有对这些基因片段 进行测序的实验室

following one of the project's two major principles:

都遵循着以下两项准则：

that collaboration on our shared heritage was open to all nations.

研究成果属于全人类，并且对世界各国公开。

In each case, the fragments were arbitrarily broken up

所有实验中，基因片段都被任意分割为

into small, overlapping pieces about 1,000 base pairs long.

更小的，有重叠部分的1000个碱基对。

Then, using a technology called the Sanger method,

随后，他们运用“桑格测序法” （注：双脱氧链终止法）

each piece was sequenced letter by letter.

将每个片段内的碱基进行逐一测序 （即A,T,C,G）。

This rigorous map-based approach called hierarchical shotgun sequencing

这一严格的图谱测序法被称作 “分级散弹枪测序法”，

minimized the risk of misassembly,

可以将错误组合风险降至最低，

a huge hazard of sequencing genomes with many repetitive portions,

这些重复组合的基因有着巨大风险，

like the human genome.

例如人类基因组。

The consortium's "better safe than sorry" approach

人类基因组计划的这项 “宁稳妥，勿遗憾”的原则，

contrasted starkly with Celera's strategy called whole genome shotgun sequencing.

与Celera公司的“全基因组散弹枪测序法” 形成鲜明对比。

It hinged on skipping the mapping phase entirely,

因为Celera公司完全跳过图谱阶段,

a faster, though foolhardy, approach according to some.

在有些人看来这是一个有勇无谋的策略。

The entire genome was directly chopped up

他们将整个基因组直接切成

into a giant heap of small, overlapping bits.

许多小而重叠的片段。

Once these bits were sequenced via the Sanger method,

一旦这些小片段完成“桑格测序”，

Celera would take the formidable risk of reconstructing the genome

Celera公司会采取风险极高的方法，

using just the overlaps.

也就是用那些重叠部分来直接重组基因。

But perhaps their decision wasn't such a gamble

可或许他们的策略并非是一场豪赌，

because guess whose freshly completed map was available online for free?

因为猜猜看是谁首先完成 可以在网上免费获得的图谱呢？

The Human Genome Consortium,

人类基因组计划

in accordance with the project's second major principle

研究中的第二项准则是，

which held that all of the project's data

要将研究中所收集的资料

would be shared publicly within 24 hours of collection.

在24小时之内公布于众。

So in 1998, scientists around the world

因此1998年，世界各国的科学家

were furiously sequencing lines of genetic code

运用实践证明过的“桑格测序法”

using the tried and true, yet laborious, Sanger method.

对各种遗传基因展开“疯狂”的测序。

Finally, after three exhausting years of continuous sequencing and assembling,

最终，经过3年艰苦漫长的 测序和重组，

the verdict was in.

比赛有结果了。

In February 2001, both groups simultaneously published

2001年二月的时候，双方同时发布了

working drafts of more than 90% of the human genome,

超过90%的人类基因组草图，

several years ahead of the consortium's schedule.

都比原先预测的进度早了好几年。

The race ended in a tie.

比赛打平了。

The Human Genome Project's practice of immediately sharing its data

人类基因组计划这种及时分享数据的

was an unusual one.

做法并不常见。

It is more typical for scientists to closely guard their data

科学家们更倾向于在他们可以

until they are able to analyze it and publish their conclusions.

分析并且发布结果的时候再公布研究数据。

Instead, the Human Genome Project accelerated the pace of research

然而，人类基因组计划的这种做法 加速了研究过程，

and created an international collaboration on an unprecedented scale.

并且促成了研究领域一项 空前的国际合作。

Since then, robust investment in both the public and private sector

自此，在公共和私人领域的 研究得到深入开发，

has led to the identification of many disease related genes

使很多与基因相关的疾病 得以被检测出来，

and remarkable advances in sequencing technology.

同时测序方法也被不断完善。

Today, a person's genome can be sequenced in just a few days.

如今，一个人的全部基因测序 只需要几天就能完成。

However, reading the genome is only the first step.

但是，能够解读基因只是第一步而已。

We're a long way away from understanding what most of our genes do

要了解大多数基因的功能 以及它们是如何被控制的，

and how they are controlled.

我们还有很漫长的路要走。

Those are some of the challenges

这些工作将要交给我们下一代

for the next generation of ambitious research initiatives.

充满进取心的研究者来完成了。