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

  • 3.2 billion base pairs long.

  • Deciphering these directions would be a monumental task

  • but could offer unprecedented insight about the human body.

  • In 1990, a consortium of 20 international research centers

  • embarked on the world's largest biological collaboration

  • to accomplish this mission.

  • The Human Genome Project proposed to sequence the entire human genome

  • over 15 years with $3 billion of public funds.

  • Then, seven years before its scheduled completion,

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

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

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

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

  • And so the race began.

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

  • it was their strategies that made all the difference.

  • Their paths diverged in the most critical of steps:

  • the first one.

  • In the Human Genome Project's approach,

  • the genome was first divided into smaller, more manageable chunks

  • about 150,000 base pairs long

  • that overlapped each other a little bit on both ends.

  • Each of these fragments of DNA

  • was inserted inside a bacterial artificial chromosome

  • where they were cloned and fingerprinted.

  • The fingerprints showed scientists where the fragments overlapped

  • without knowing the actual sequence.

  • Using the overlapping bits as a guide,

  • the researchers marked each fragment's place in the genome

  • to create a contiguous map,

  • a process that took about six years.

  • The cloned fragments were sequenced in labs around the world

  • following one of the project's two major principles:

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

  • In each case, the fragments were arbitrarily broken up

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

  • Then, using a technology called the Sanger method,

  • each piece was sequenced letter by letter.

  • This rigorous map-based approach called hierarchical shotgun sequencing

  • minimized the risk of misassembly,

  • a huge hazard of sequencing genomes with many repetitive portions,

  • like the human genome.

  • The consortium's "better safe than sorry" approach

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

  • It hinged on skipping the mapping phase entirely,

  • a faster, though foolhardy, approach according to some.

  • The entire genome was directly chopped up

  • into a giant heap of small, overlapping bits.

  • Once these bits were sequenced via the Sanger method,

  • Celera would take the formidable risk of reconstructing the genome

  • using just the overlaps.

  • But perhaps their decision wasn't such a gamble

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

  • The Human Genome Consortium,

  • in accordance with the project's second major principle

  • which held that all of the project's data

  • would be shared publicly within 24 hours of collection.

  • So in 1998, scientists around the world

  • were furiously sequencing lines of genetic code

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

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

  • the verdict was in.

  • In February 2001, both groups simultaneously published

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

  • several years ahead of the consortium's schedule.

  • The race ended in a tie.

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

  • was an unusual one.

  • It is more typical for scientists to closely guard their data

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

  • Instead, the Human Genome Project accelerated the pace of research

  • and created an international collaboration on an unprecedented scale.

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

  • has led to the identification of many disease related genes

  • and remarkable advances in sequencing technology.

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

  • However, reading the genome is only the first step.

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

  • and how they are controlled.

  • Those are some of the challenges

  • for the next generation of ambitious research initiatives.

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

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TED-ED】ヒトゲノムの配列決定競争 - ティエン・グエン (【TED-Ed】The race to sequence the human genome - Tien Nguyen)

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    Ann に公開 2021 年 01 月 14 日
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