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  • Youve probably heard of CRISPR technologies and their much-discussed ability to edit our

  • DNA.

  • For the most part, these stories probably refer to CRISPR-Cas9.

  • But a new system, CRISPR-Cas3, has just been used in human cells for the very first time...and

  • offers a whole new set of tools that could have huge implications for curing previously

  • incurable viruses.

  • To review, CRISPR-Cas9 is the combination of a custom-made piece of RNA (that’s the

  • clustered regularly interspersed palindromic repeats, or the CRISPR part) and an enzyme

  • (that’s the CRISPR associated protein 9, or Cas-9 part).

  • The RNA is engineered to recognize a certain segment of DNA, which guides the CRISPR-Cas9

  • system to that section so it can then cut and delete, or potentially add to, or even

  • replace with an altered version.

  • CRISPR-Cas9 belongs to a family of CRISPR-based editing tools called Class 2 systems.

  • There are actually three classes of CRISPR-Cas systems, most of them belonging to classes

  • one and two.

  • CRISPR-Cas3 is a Class 1 system.

  • Class 1 systems are apparently more prevalent in our biological processes and are more sophisticated

  • than Class 2 systems, but have so far theyve only been used experimentally as gene editing

  • tools in bacteria and archaea.

  • CRISPR-Cas3 has the unique capability to search for, identify, and delete much longer stretches

  • of DNA than CRISPR-Cas9, chunks up to 100,000 base pairs longand it makes multiple cuts

  • along that chunk, kind of like a shredder.

  • A research team that recently demonstrated this in human cells for the first time--in

  • a petri dish--believes the Cas3 system could be a better option than Cas9 because it uses

  • a longer guide RNA sequence.

  • This means it’s better at more accurately locating the chunk we want to target.

  • This makes it ideal for editing non-coding segments of our genome.

  • These are pieces of our DNA, about 98% of it, actually, that don’t directly correlate

  • to something.

  • Instead they act as regulators, determining how much that gene is expressed, if at all.

  • We don’t have a great understanding of what this huge swathe of our DNA really does, so

  • using CRISPR-Cas3 to delete large sections and then seeing what happens, in a lab setting

  • of course, could give us a much better understanding of what these non-coding sections do and how

  • they work.

  • CRISPR-Cas3 could also delete sections of genes that have been permanently altered by

  • viruses.

  • Diseases like herpes actually hijack our DNA, inserting their sequences into our genome

  • to use our cell’s machinery to make their own often malicious proteins.

  • Herpes in particular is spectacularly good at avoiding our immune system and goes through

  • dormant stages, making it impossible to cure.

  • But its permanent alterations of our DNA could make it vulnerable to attack by CRISPR technologies,

  • and CRISPR-Cas3’s accurate targeting and powerful shredding capabilities could knock

  • it out of our system for good.

  • Some other teams are pointing to CRISPR-Cas3 as a potential solution for antibiotic-resistant

  • bacteria.

  • Instead of deleting a sequence of DNA infected by a virusDNA, CRISPR-Cas3 could just

  • chew up the bacterium’s whole genome beyond the point of repair, causing the organism’s

  • deathno antibiotics required!

  • So, CRISPR-Cas3 has the potential to delete large chunks of our DNA, proving useful and

  • potentially more efficient and cost-effective in some essential medical situationsbut

  • we still have to learn how to control it.

  • While the most recent study into CRISPR-Cas3’s potential did demonstrate that we can use

  • it in human cells, we still don’t have total control over how long a section we tell it

  • to delete.

  • And of course, since were not even entirely sure of the complete function of most of our

  • genes, we would want to make sure the stuff were deleting is, y’know...safe to delete.

  • Or that we have a healthy version to replace it with, some kind of backup plan.

  • There are all kinds of new studies coming out about the unexpected effects of CRISPR-Cas9—

  • deletions we didn’t mean to make and didn’t see comingso with all of this gene-editing

  • stuff well need to proceed with extreme caution and many more years of experimentation

  • before we see this in a clinical setting.

  • But this new exploration of CRISPR-Cas3’s potential is an exciting first proof-of-concept

  • for a technology that could one day provide a solution for previously incurable viruses.

  • If you want to learn more about viruses, you should check out our new show, Sick.

  • It's all about what's happening in your body when things start to go wrong.

  • We're talking Lyme disease, measles, lupus, and more.

  • Is there a disease or illness you want us to cover?

  • Let us know down in the comments.

  • Make sure to subscribe to get all your science news.

  • Thanks for watching.

Youve probably heard of CRISPR technologies and their much-discussed ability to edit our

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B1 中級

新的CRISPR工具,可以從我們的DNA中 "刪除 "疾病。 (The New CRISPR Tool That Could ‘Delete’ Disease From Our DNA)

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    林宜悉 發佈於 2021 年 01 月 14 日
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