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  • Every living being needs to fight off other living beings that want to feast on them.​

    どんな生物でも 天敵と戦わなければならない

  • Every living being needs to fight off other living beings that want to feast on them.​

    多細胞生物は何十億年もの進化を経て 防衛手段を身に付けた

  • Every living being needs to fight off other living beings that want to feast on them.​

    今では 人間は高度な防御機構を持つ

  • So as multicellular life evolved over billions of years, it came up with ways to defend itself.​

    物理的な障壁・防御細胞・武器工場などだ

  • So as multicellular life evolved over billions of years, it came up with ways to defend itself.​

    しかし かなり重要な防御機構なのに あまり知られていないものが一つある

  • So as multicellular life evolved over billions of years, it came up with ways to defend itself.​

    それが「補体系」だ

  • Today humans have a sophisticated defense network,​

    7億年以上前の進化で獲得した能力で

  • Today humans have a sophisticated defense network,​

    30種以上のタンパク質の大群が

  • Today humans have a sophisticated defense network,​

    複雑・華麗な動きで 協調して侵入者を食い止める

  • like physical barriers, defense cells, and weapons factories.​

    およそ1500垓(京の1万倍)個の大群が 今もあなたの体液を満たしている

  • like physical barriers, defense cells, and weapons factories.​

    化学物質で誘導されると

  • like physical barriers, defense cells, and weapons factories.​

    このタンパク質は 侵入者への超強力な対抗手段となる

  • But one of the most important defenses of our body is largely unknown:​

    他の免疫システムは 補体系を活性化させるツールに過ぎない

  • But one of the most important defenses of our body is largely unknown:​

    だが同時に危険もはらむ

  • But one of the most important defenses of our body is largely unknown:​

    今にも爆発する小型爆弾が 血液中に何兆個とあるようなものだ

  • The Complement System

    そのため我々の細胞は 様々な方法で 補体がうっかり自己を攻撃するのを防いでいる

  • The Complement System

    では 補体は何をしているのか? なぜそんなに危険なのだろうか?

  • The Complement System

    簡単に言うと 補体系の役割は3つある

  • It evolved over 700 million years ago and is an army of over 30 different proteins

    敵の無力化、免疫システムの活性化 そして敵に穴を開けて殺すことだ

  • It evolved over 700 million years ago and is an army of over 30 different proteins

    「でもどうやって?」

  • It evolved over 700 million years ago and is an army of over 30 different proteins

    「意志や目的地もなく ランダムに漂うただのタンパク質じゃないか」

  • that work together in a complex and elegant dance to stop intruders.​

    まあ 実はこれも戦略の一部だ

  • that work together in a complex and elegant dance to stop intruders.​

    補体タンパク質はある種の迎撃態勢で浮遊する

  • that work together in a complex and elegant dance to stop intruders.​

    活性化して変形するまでは何もしない

  • All in all, about 15 quintillion of them are saturating every fluid in your body right now.​

    タンパク質の世界では 何ができて何ができないかは形が決める

  • All in all, about 15 quintillion of them are saturating every fluid in your body right now.​

    なぜなら 誰に・どのように働きかけるかは 形で決まるからだ

  • All in all, about 15 quintillion of them are saturating every fluid in your body right now.​

    例えば 不活性状態では特に何も起こらないが

  • Guided by nothing but chemistry,​

    変形して活性化すると 他のタンパク質に働きかけるようになり

  • Guided by nothing but chemistry,​

    そのタンパク質も形を変えて 以下同様な反応が続く

  • Guided by nothing but chemistry,​

    このような仕組みで 一度始まった反応は急速に広がっていく

  • these proteins are one of the most effective weapons we have against invaders.​

    補体タンパク質は 密集した何百万本ものマッチのようなものだ

  • these proteins are one of the most effective weapons we have against invaders.​

    一本に火が付くと 周りのマッチにも火が移り

  • these proteins are one of the most effective weapons we have against invaders.​

    どんどん燃え広がって 一気に大きな炎になる

  • Many other parts of the immune system are just tools to activate the Complement System.​

    補体系を全て説明するのは やや複雑で気が滅入るので

  • Many other parts of the immune system are just tools to activate the Complement System.​

    かみ砕いて説明する

  • Many other parts of the immune system are just tools to activate the Complement System.​

    例えば切り傷を負ったとする

  • But it's also really dangerous.​

    大量の細菌が傷口から入って 周囲の組織に広がっていくだろう

  • But it's also really dangerous.​

    補体の攻撃は「C3」から始まる

  • But it's also really dangerous.​

    C3は一本目のマッチで 炎の元となる最初の火花だ

  • Imagine having trillions of little bombs inside your blood that could go off at any moment.​

    火花を発生させるには C3を活性化させる必要がある

  • Imagine having trillions of little bombs inside your blood that could go off at any moment.​

    仕組みは複雑なのだが

  • Imagine having trillions of little bombs inside your blood that could go off at any moment.​

    ランダムに起こる反応だと言っておこう

  • So our cells use numerous mechanisms to prevent​ ​complement from accidentally attacking ​​them​.​

    反応は敵にくっついた別の補体タンパク質や 抗体を通じて起こる

  • So our cells use numerous mechanisms to prevent​ ​complement from accidentally attacking ​​them​.​

    重要なのは C3が2つのタンパク質に分離し

  • So our cells use numerous mechanisms to prevent​ ​complement from accidentally attacking ​​them​.​

    C3aとC3bが活性化することだ

  • Okay, what exactly does it do and what makes it so dangerous?​

    C3から分かれたC3bタンパク質は

  • Okay, what exactly does it do and what makes it so dangerous?​

    ホーミング弾のようなもので

  • Okay, what exactly does it do and what makes it so dangerous?​

    細菌・菌類・ウイルスに特化している

  • In a nutshell, The Complement System does three things:​

    標的を探すのに与えられた時間は一瞬で

  • In a nutshell, The Complement System does three things:​

    それを過ぎると水分子で不活性化される

  • In a nutshell, The Complement System does three things:​

    C3bが標的を見つけると

  • it cripples enemies, it activates the immune system, and it rips holes in things until they die.​

    標的の表面上で強力に固定され 離れないようになる

  • it cripples enemies, it activates the immune system, and it rips holes in things until they die.​

    そうすると タンパク質は再び変形する

  • it cripples enemies, it activates the immune system, and it rips holes in things until they die.​

    新しい形になると 他のタンパク質と結合し

  • But, how?​

    小規模の反応が始まる

  • But, how?​

    形は次々に変わっていき 他の補体タンパク質と一体化していく

  • But, how?​

    最終的には 「C3コンバターゼ」で知られる再生産工場に変形する

  • After all, these are mindless proteins randomly drifting around without will or direction.​

    この工場は C3の一連の反応を促進させるのに特化している

  • After all, these are mindless proteins randomly drifting around without will or direction.​

    こうして増幅ループが始まり

  • After all, these are mindless proteins randomly drifting around without will or direction.​

    間もなく何千ものタンパク質が細菌を覆う

  • Well, this is actually part of the strategy.​

    細菌にとっては大変よろしくない事態だ

  • Well, this is actually part of the strategy.​

    体にまとわりつかれて 無力化ないし消耗させられるからだ

  • Well, this is actually part of the strategy.​

    何千匹ものハエに覆われていると想像すればいい

  • Complement proteins float around in a sort-of passive mode.​

    だが、思い出してほしい

  • Complement proteins float around in a sort-of passive mode.​

    C3の分身はまだ他にもあった

  • Complement proteins float around in a sort-of passive mode.​

    そう、「C3aタンパク質」だ

  • They do nothing, until they get activated and change their shape.​

    C3aは救難信号のようなものだ

  • They do nothing, until they get activated and change their shape.​

    何千ものC3aが流れていき 戦場から離れた場所に危険を知らせる

  • They do nothing, until they get activated and change their shape.​

    免疫細胞がC3aタンパク質を感知すると

  • In the world of proteins, your shape determines what you can and cannot do.​

    眠りから覚め C3bタンパク質を辿って 感染部位まで移動する

  • In the world of proteins, your shape determines what you can and cannot do.​

    細胞が出会うC3bが多いほど 細胞はより活性化する

  • In the world of proteins, your shape determines what you can and cannot do.​

    こうして 補体が援軍を適材適所へと導く

  • Because shape determines what you can interact with and in what way.​

    ここまでは 補体は侵入者の動きを鈍くさせるか 助けを呼んでくるだけだったが

  • Because shape determines what you can interact with and in what way.​

    ここからは 補体も積極的に敵の処分を支援し始める

  • Because shape determines what you can interact with and in what way.​

    戦場に真っ先に到着する免疫細胞は「食細胞」だ

  • For example, in your passive shape you might do nothing.​

    この細胞は敵を丸々飲み込むと

  • For example, in your passive shape you might do nothing.​

    小さな檻に閉じ込めたまま 酸で溶かして殺す

  • For example, in your passive shape you might do nothing.​

    しかし 飲み込むには敵を掴む必要がある

  • In your active shape, however, you might, for example, change the shape of other proteins

    細菌はツルツルで掴みにくいので そう簡単ではない

  • In your active shape, however, you might, for example, change the shape of other proteins

    だが細菌に固定された補体が一種の接着剤として働き

  • In your active shape, however, you might, for example, change the shape of other proteins

    免疫細胞が標的を捕まえるのを容易にする

  • activating them so they can activate others.​

    しかしこれだけでは終わらない

  • activating them so they can activate others.​

    ハエの例えを思い出そう

  • activating them so they can activate others.​

    ハエがハチになったらどうなるだろう

  • Mechanisms like this one can start cascades that spread very quickly.​

    反応経路は他にもある

  • Mechanisms like this one can start cascades that spread very quickly.​

    細胞表面のC3コンバターゼがその形を再び変えて

  • Mechanisms like this one can start cascades that spread very quickly.​

    新しいタンパク質を呼び込み始める

  • Imagine the complement proteins as being like millions of matches very close together.​

    それらはより大きな構造体を構築する

  • Imagine the complement proteins as being like millions of matches very close together.​

    それが「膜侵襲複合体」だ

  • Imagine the complement proteins as being like millions of matches very close together.​

    長槍のような形をした別のタンパク質が 一本ずつやってきて

  • Once one catches fire, it ignites the ones around it.​

    絶対に塞げない程の穴が開くまで

  • Once one catches fire, it ignites the ones around it.​

    細菌の細胞膜深くに打ち込まれていく

  • Once one catches fire, it ignites the ones around it.​

    液体が外から内に流れ込み 細菌の中身が外に漏れ出てくる

  • They ignite more and suddenly you have a big fire.​

    細菌の出血死だ

  • They ignite more and suddenly you have a big fire.​

    残りの細菌も攻撃してくる補体に気を取られ

  • They ignite more and suddenly you have a big fire.​

    到着した免疫細胞に素早く処理される

  • To show the actual mechanisms of The Complement System is a tad complicated and overwhelming.​

    大事に至る前に 侵入者を早い段階で潰すことができた

  • To show the actual mechanisms of The Complement System is a tad complicated and overwhelming.​

    まあ本人は知る由もない

  • To show the actual mechanisms of The Complement System is a tad complicated and overwhelming.​

    細菌は補体のことを快く思わないが

  • So, we'll simplify here.​

    補体はウイルスにこそ最も効果的に働く

  • So, we'll simplify here.​

    ウイルスには弱点が一つある 細胞から細胞へと移動しなければならないことだ

  • So, we'll simplify here.​

    細胞外ではランダムに細胞にぶつかっていくので 感染するかどうかは運次第だ

  • Now, let's imagine you cut yourself and a bunch of bacteria enter the wound

    細胞外では全く無防備なので

  • Now, let's imagine you cut yourself and a bunch of bacteria enter the wound

    ウイルスは補体に迎撃・無力化され

  • Now, let's imagine you cut yourself and a bunch of bacteria enter the wound

    無害化されたのちに 免疫システムに導かれ貪食される

  • and make it into the surrounding tissue.​

    補体が無ければ ウイルス感染はもっと致命的だったであろう

  • and make it into the surrounding tissue.​

    しかし 補体がそれほど強力なら どうして病気に罹るのか

  • and make it into the surrounding tissue.​

    理由は 敵も補体に対抗してくるからだ

  • Our complement attack begins with C3.​

    例えば ワクシニアウイルスは細胞に感染すると

  • Our complement attack begins with C3.​

    補体を不活化させるタンパク質を細胞に産生させる

  • Our complement attack begins with C3.​

    こうして 感染細胞の周りに ウイルスの安全地帯が出来上がる

  • C3 is the first match, the initial spark that will start our fire.​

    細胞は死滅し感染は広がるので 症状が出る可能性は高くなる

  • C3 is the first match, the initial spark that will start our fire.​

    補体系を鎮静化させる物質を血中から横取りし 透明になってやり過ごす細菌もいる

  • C3 is the first match, the initial spark that will start our fire.​

    要するに 補体系はとても重要だが

  • And to do that, C3 needs to switch from passive to active.​

    複雑で美しい免疫システムを組織する 一構成員に過ぎない

  • And to do that, C3 needs to switch from passive to active.​

    「個々では弱くとも協力すれば知性を発揮できる」

  • And to do that, C3 needs to switch from passive to active.​

    免疫システムは我々にそう教えてくれる

  • How this happens is complex, but let's just say it can happen randomly

    この動画はあなたの支援で制作できています

  • How this happens is complex, but let's just say it can happen randomly

    あなたの直接の支援が無ければ このチャンネルは立ち行かなかったでしょう

  • How this happens is complex, but let's just say it can happen randomly

    そのことには本当に感謝してもしきれません

  • through other complement proteins that bind to enemies or through antibodies.​

    2019年は kurzgesagtの動画を一本制作するのに 最低でも1200時間はかかりました

  • through other complement proteins that bind to enemies or through antibodies.​

    私たちは数ヶ月かけて 調査・草稿の作成・専門家との協議

  • through other complement proteins that bind to enemies or through antibodies.​

    全イラスト・アニメーションの作成 オリジナル音声の作成をこなします

  • All you really need to know is that C3 breaks into two smaller proteins,​

    これもひとえにスポンサーの方々や

  • All you really need to know is that C3 breaks into two smaller proteins,​

    Patreonで寄付して下さる視聴者の方

  • All you really need to know is that C3 breaks into two smaller proteins,​

    補体系をテーマにしたポスターやポストカードなどを 購入して下さる方々のおかげです

  • C3a and C3b, that are now activated.​

    もし支援して下さるのなら

  • C3a and C3b, that are now activated.​

    動画を見たり Patreonで寄付したり できればパーソナルバードをゲットしたりして下さい

  • C3a and C3b, that are now activated.​

    カレンダーやポスターを購入して下さるだけでも 励みになります

  • One of these parts, the C3b protein, is like a seeker missile specialized in bacteria, fungi, and viruses.​

    Kurzgesagtの意義は 精一杯制作した最高の動画を通して

  • One of these parts, the C3b protein, is like a seeker missile specialized in bacteria, fungi, and viruses.​

    科学にもっと親しみを持ってもらうことです

  • One of these parts, the C3b protein, is like a seeker missile specialized in bacteria, fungi, and viruses.​

    いつも応援してくださりありがとうございます

  • It has a fraction of a second to find a victim or it will be neutralized by water molecules.​

  • It has a fraction of a second to find a victim or it will be neutralized by water molecules.​

  • It has a fraction of a second to find a victim or it will be neutralized by water molecules.​

  • If C3b does find a target, it anchors itself very tightly to its surface and doesn't let go.​

  • If C3b does find a target, it anchors itself very tightly to its surface and doesn't let go.​

  • If C3b does find a target, it anchors itself very tightly to its surface and doesn't let go.​

  • By doing so, the protein changes its shape again.​

  • By doing so, the protein changes its shape again.​

  • By doing so, the protein changes its shape again.​

  • In its new shape, it's now able to grab other proteins and start a small cascade,​

  • In its new shape, it's now able to grab other proteins and start a small cascade,​

  • In its new shape, it's now able to grab other proteins and start a small cascade,​

  • changing its shape multiple times, adding other complement proteins to itself.​

  • changing its shape multiple times, adding other complement proteins to itself.​

  • changing its shape multiple times, adding other complement proteins to itself.​

  • Finally, it transforms itself into a recruiting platform known as C3 Convertase.​

  • Finally, it transforms itself into a recruiting platform known as C3 Convertase.​

  • Finally, it transforms itself into a recruiting platform known as C3 Convertase.​

  • This platform is an expert at activating more C3 proteins that start the whole cycle anew.​

  • This platform is an expert at activating more C3 proteins that start the whole cycle anew.​

  • This platform is an expert at activating more C3 proteins that start the whole cycle anew.​

  • An amplification loop begins.​

  • An amplification loop begins.​

  • An amplification loop begins.​

  • Soon, thousands of proteins cover the bacteria.​

  • Soon, thousands of proteins cover the bacteria.​

  • Soon, thousands of proteins cover the bacteria.​

  • For the bacteria, this is very bad.​

  • For the bacteria, this is very bad.​

  • For the bacteria, this is very bad.​

  • It can cripple the bacteria and make them helpless, or slow them down.​

  • It can cripple the bacteria and make them helpless, or slow them down.​

  • It can cripple the bacteria and make them helpless, or slow them down.​

  • Imagine being covered by thousands of flies.​

  • Imagine being covered by thousands of flies.​

  • Imagine being covered by thousands of flies.​

  • But, there's more.​

  • But, there's more.​

  • But, there's more.​

  • Do you remember the other part of C3—the C3a protein?​

  • Do you remember the other part of C3—the C3a protein?​

  • Do you remember the other part of C3—the C3a protein?​

  • C3a is like a distress beacon.​

  • C3a is like a distress beacon.​

  • C3a is like a distress beacon.​

  • Thousands of them flood away from the site of battle screaming for attention.​

  • Thousands of them flood away from the site of battle screaming for attention.​

  • Thousands of them flood away from the site of battle screaming for attention.​

  • Passive immune cells notice the C3a proteins,​

  • Passive immune cells notice the C3a proteins,​

  • Passive immune cells notice the C3a proteins,​

  • and awaken from their slumber to follow the protein tracks to the site of infection.​

  • and awaken from their slumber to follow the protein tracks to the site of infection.​

  • and awaken from their slumber to follow the protein tracks to the site of infection.​

  • The more alarm proteins they encounter, the more aggressive they get.​

  • The more alarm proteins they encounter, the more aggressive they get.​

  • The more alarm proteins they encounter, the more aggressive they get.​

  • This way, complement guides reinforcements exactly to the place where they're needed the most.​

  • This way, complement guides reinforcements exactly to the place where they're needed the most.​

  • This way, complement guides reinforcements exactly to the place where they're needed the most.​

  • So far, the complement has slowed down the invaders and called for help.​

  • So far, the complement has slowed down the invaders and called for help.​

  • So far, the complement has slowed down the invaders and called for help.​

  • Now, it's beginning to actively help to kill the enemy.​

  • Now, it's beginning to actively help to kill the enemy.​

  • Now, it's beginning to actively help to kill the enemy.​

  • The first immune cells to arrive at the battlefield are ​​phagocytes​.​

  • The first immune cells to arrive at the battlefield are ​​phagocytes​.​

  • The first immune cells to arrive at the battlefield are ​​phagocytes​.​

  • Which means, cells that swallow you whole, trap you in a tiny prison, and then kill you with acid.​

  • Which means, cells that swallow you whole, trap you in a tiny prison, and then kill you with acid.​

  • Which means, cells that swallow you whole, trap you in a tiny prison, and then kill you with acid.​

  • But, to swallow an enemy, they need to grab it first.​

  • But, to swallow an enemy, they need to grab it first.​

  • But, to swallow an enemy, they need to grab it first.​

  • Which is not easy because bacteria prefer not to be grabbed and are sort-of slippery.​

  • Which is not easy because bacteria prefer not to be grabbed and are sort-of slippery.​

  • Which is not easy because bacteria prefer not to be grabbed and are sort-of slippery.​

  • But now, the complement that has anchored itself to the bacteria

  • But now, the complement that has anchored itself to the bacteria

  • But now, the complement that has anchored itself to the bacteria

  • acts as a sort-of glue that makes it easy for the immune cells to catch their victims.​

  • acts as a sort-of glue that makes it easy for the immune cells to catch their victims.​

  • acts as a sort-of glue that makes it easy for the immune cells to catch their victims.​

  • But it gets even better.​

  • But it gets even better.​

  • But it gets even better.​

  • Imagine being covered in flies again.​

  • Imagine being covered in flies again.​

  • Imagine being covered in flies again.​

  • Now, imagine them turning into wasps.​

  • Now, imagine them turning into wasps.​

  • Now, imagine them turning into wasps.​

  • Another cascade is about to begin.​

  • Another cascade is about to begin.​

  • Another cascade is about to begin.​

  • On the surface of a bacteria, the C3 recruitment platform changes its shape again

  • On the surface of a bacteria, the C3 recruitment platform changes its shape again