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.​