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  • Bacteria are the oldest living organisms on the earth.

    細菌是地球上最古老的生命體。

  • They've been here for billions of years,

    它們已經存在數十億年了,

  • and what they are are single-celled microscopic organisms.

    它們是單細胞微生物。

  • So they are one cell and they have this special property

    它們只有一個細胞,而且還有個特徵

  • that they only have one piece of DNA.

    就是只有一份 DNA。

  • They have very few genes,

    擁有極少的基因

  • and genetic information to encode all of the traits that they carry out.

    及遺傳資訊,來儲存所有它們表現的特徵。

  • And the way bacteria make a living

    細菌賴以生存的方法是

  • is that they consume nutrients from the environment,

    從環境中吸取養分,

  • they grow to twice their size, they cut themselves down in the middle,

    成長兩倍後,從中分開,

  • and one cell becomes two, and so on and so on.

    一分為二,二分為四,如此一直下去。

  • They just grow and divide, and grow and divide -- so a kind of boring life,

    它們不停生長、分裂,然後再生長、分裂 — 有點無趣的生活,

  • except that what I would argue is that you have

    但是我會說你與這些生物

  • an amazing interaction with these critters.

    擁有驚人的互動關係。

  • I know you guys think of yourself as humans, and this is sort of how I think of you.

    我知道你們自認是人類,而這大概是我如何看待你們的。

  • This man is supposed to represent

    這個人是代表

  • a generic human being,

    一般的人類,

  • and all of the circles in that man are all of the cells that make up your body.

    那些人體內的圈圈,代表組成人體的細胞。

  • There is about a trillion human cells that make each one of us

    每個人大約是由一兆個人體細胞所組成,

  • who we are and able to do all the things that we do,

    讓我們能完成各式各樣的事

  • but you have 10 trillion bacterial cells

    但是你一生中任何時刻

  • in you or on you at any moment in your life.

    都有大約十兆個細菌細胞在你身上或體內。

  • So, 10 times more bacterial cells

    所以,在一個人身上

  • than human cells on a human being.

    有人體細胞數十倍的細菌細胞。

  • And of course it's the DNA that counts,

    當然,DNA 組成比細胞數重要,

  • so here's all the A, T, Gs and Cs

    所以這裡是組成你遺傳密碼的

  • that make up your genetic code, and give you all your charming characteristics.

    所有 A, T, G, C,它們產生了你專屬的迷人特徵。

  • You have about 30,000 genes.

    你有大約三萬個基因。

  • Well it turns out you have 100 times more bacterial genes

    但事實上,你身上的細菌基因是你本身基因的一百多倍!

  • playing a role in you or on you all of your life.

    在你的身上或體內扮演著某些腳色。

  • At the best, you're 10 percent human,

    最多最多,你只是 10% 的人類,

  • but more likely about one percent human,

    其實更有可能只是 1% 的人類,

  • depending on which of these metrics you like.

    端看你喜歡哪一種度量方法。

  • I know you think of yourself as human beings,

    我知道你認為你自己是人類,

  • but I think of you as 90 or 99 percent bacterial.

    但在我眼中你是 90% 或 99% 的細菌。

  • (Laughter)

    (笑聲)

  • These bacteria are not passive riders,

    這些細菌不只是被動的乘客而已,

  • these are incredibly important, they keep us alive.

    它們非常地重要,它們維持我們的生命。

  • They cover us in an invisible body armor

    它們將我們保護在一層看不見的鎧甲中,

  • that keeps environmental insults out

    隔絕環境刺激,

  • so that we stay healthy.

    因此我們能保持健康。

  • They digest our food, they make our vitamins,

    它們消化我們的食物,製造我們所需的維他命,

  • they actually educate your immune system

    它們還教育你的免疫系統

  • to keep bad microbes out.

    將惡性微生物阻擋於體外。

  • So they do all these amazing things

    它們做了這些了不起的事,

  • that help us and are vital for keeping us alive,

    幫助我們,是我們賴以為生的關鍵,

  • and they never get any press for that.

    但細菌從來沒有因為這些好事上過媒體

  • But they get a lot of press because they do a lot of

    倒是常常因為它們也能導致許多可怕的後果

  • terrible things as well.

    而登上各大版面

  • So, there's all kinds of bacteria on the Earth

    地球上有各式各樣的細菌

  • that have no business being in you or on you at any time,

    有些絕不應該出現在你身上或體內

  • and if they are, they make you incredibly sick.

    如果有,它們會讓你極端難受。

  • And so, the question for my lab is whether you want to think about all the

    因此,我實驗室的研究主題是,所有你想得到細菌做的好事

  • good things that bacteria do, or all the bad things that bacteria do.

    或是所有細菌做的壞事。

  • The question we had is how could they do anything at all?

    並且探討,它們是如何辦到的?

  • I mean they're incredibly small,

    畢竟它們十分的小,

  • you have to have a microscope to see one.

    你必須在顯微鏡底下才能觀察到它們。

  • They live this sort of boring life where they grow and divide,

    它們的生活如此無趣,只是成長與分裂,

  • and they've always been considered to be these asocial reclusive organisms.

    而且它們總被認為是無社會行為的獨行俠

  • And so it seemed to us that they are just too small to have an impact

    所以對我們來說,它們實在是

  • on the environment

    微小到無法對環境產生任何影響

  • if they simply act as individuals.

    尤其它們只是單獨行動的話。

  • And so we wanted to think if there couldn't be a different

    所以我們想探討,

  • way that bacteria live.

    細菌是不是其實用別種方式生存?

  • The clue to this came from another marine bacterium,

    這個問題的線索,來自一種海洋細菌,

  • and it's a bacterium called Vibrio fischeri.

    叫做費氏弧菌 (Vibrio fischeri) 。

  • What you're looking at on this slide is just a person from my lab

    你們在這張投影片看到的,是我實驗室的一個人

  • holding a flask of a liquid culture of a bacterium,

    握著一瓶裝滿這種細菌的培養液

  • a harmless beautiful bacterium that comes from the ocean,

    一種來自海洋,美麗且無害的細菌,

  • named Vibrio fischeri.

    名為費氏弧菌 (Vibrio fischeri)。

  • This bacterium has the special property that it makes light,

    這種細菌的特性是會發光,

  • so it makes bioluminescence,

    它會發出生物螢光,

  • like fireflies make light.

    就如同螢火蟲發出的光。

  • We're not doing anything to the cells here.

    我們沒有對這些細胞做任何事。

  • We just took the picture by turning the lights off in the room,

    我們只是把房間燈關了,然後照了這張照片,

  • and this is what we see.

    這是我們所見到的情形。

  • What was actually interesting to us

    我們尤其感興趣的

  • was not that the bacteria made light,

    不是細菌會發光這件事,

  • but when the bacteria made light.

    而是細菌何時發光。

  • What we noticed is when the bacteria were alone,

    我們注意到當細菌處於單獨環境中,

  • so when they were in dilute suspension, they made no light.

    也就是當它們被稀釋,且懸浮在培養液中時,它們不會發光。

  • But when they grew to a certain cell number

    但是當它們成長至一定數量後,

  • all the bacteria turned on light simultaneously.

    所有細菌會同時開始發光。

  • The question that we had is how can bacteria, these primitive organisms,

    我們疑惑的是,像細菌這麼原始的生物,

  • tell the difference from times when they're alone,

    如何能夠分辨它們現在是單獨

  • and times when they're in a community,

    還是處於群體中

  • and then all do something together.

    然後能夠一起開始從事某種行為。

  • What we've figured out is that the way that they do that is that they talk to each other,

    我們已經發現,這是因為細菌能夠彼此「對談」

  • and they talk with a chemical language.

    它們說的是化學語言

  • This is now supposed to be my bacterial cell.

    假設這個是我的細菌。

  • When it's alone it doesn't make any light.

    當它獨處時,不會發出任何光線。

  • But what it does do is to make and secrete small molecules

    但是它會製造與分泌化學小分子,

  • that you can think of like hormones,

    你可以將它想成荷爾蒙,

  • and these are the red triangles, and when the bacteria is alone

    這邊以紅色三角形代表,當細菌獨處的時候,

  • the molecules just float away and so no light.

    這些分子都擴散開來,因此沒有發光。

  • But when the bacteria grow and double

    但是當這些細菌成長倍增後,

  • and they're all participating in making these molecules,

    它們全都一起製造這些分子,

  • the molecule -- the extracellular amount of that molecule

    這些細胞外分子的含量,

  • increases in proportion to cell number.

    隨著細胞數的增加而增加。

  • And when the molecule hits a certain amount

    等這個分子累積到一定的量之後,

  • that tells the bacteria how many neighbors there are,

    它告訴了細菌,它周圍有多少鄰居,

  • they recognize that molecule

    它們都認識這個分子,

  • and all of the bacteria turn on light in synchrony.

    然後所有細菌,協同一致地開始發光。

  • That's how bioluminescence works --

    這就是它們如何一起發光—

  • they're talking with these chemical words.

    它們藉由這些化學語言交談著。

  • The reason that Vibrio fischeri is doing that comes from the biology.

    費式弧菌的發光現象有它生物學上的原因

  • Again, another plug for the animals in the ocean,

    再一次地,又連結到海洋裡的生物,

  • Vibrio fischeri lives in this squid.

    費式弧菌住在這種烏賊體內

  • What you are looking at is the Hawaiian Bobtail Squid,

    你們現在看到的是,夏威夷截尾烏賊,

  • and it's been turned on its back,

    這是牠的腹側,

  • and what I hope you can see are these two glowing lobes

    我希望你們看得到,那兩個發著光的葉狀突起,

  • and these house the Vibrio fischeri cells,

    它們內部儲藏著這些費式弧菌

  • they live in there, at high cell number

    它們就以非常高的數量,居住在那裡面,

  • that molecule is there, and they're making light.

    這個分子也在那,所以它們發著光。

  • The reason the squid is willing to put up with these shenanigans

    這烏賊之所以願意忍受這些胡鬧行為的原因是,

  • is because it wants that light.

    牠想要這些光線。

  • The way that this symbiosis works

    這個共生行為建立的基礎是

  • is that this little squid lives just off the coast of Hawaii,

    因為這個小烏賊居住在夏威夷的海岸邊,

  • just in sort of shallow knee-deep water.

    牠們生活的海域,大概只有膝蓋一般的深度。

  • The squid is nocturnal, so during the day

    這烏賊是夜行性的,因此白天

  • it buries itself in the sand and sleeps,

    牠把牠自己埋藏在沙中睡覺,

  • but then at night it has to come out to hunt.

    但是到了晚上,牠必須出來獵食。

  • On bright nights when there is lots of starlight or moonlight

    在有許多星光與月光點綴的明亮夜晚,

  • that light can penetrate the depth of the water

    這些光線可以穿透烏賊所住的地方

  • the squid lives in, since it's just in those couple feet of water.

    因為這裡的海水只有數呎深而已。

  • What the squid has developed is a shutter

    這烏賊發展出了一種活葉遮板,

  • that can open and close over this specialized light organ housing the bacteria.

    可以打開或遮蔽由特化發光器官裡的細菌所發出的光線

  • Then it has detectors on its back

    加上這烏賊背上有一些感光裝置,

  • so it can sense how much starlight or moonlight is hitting its back.

    可以用來偵測有多少月光或星光照在牠背上。

  • And it opens and closes the shutter

    然後牠隨之調節遮板的開關,

  • so the amount of light coming out of the bottom --

    因此從牠腹部所放出的光 —

  • which is made by the bacterium --

    是由細菌產生的

  • exactly matches how much light hits the squid's back,

    完全符合照射在這烏賊背部上的光強度,

  • so the squid doesn't make a shadow.

    因此這烏賊不會產生任何影子。

  • It actually uses the light from the bacteria

    牠使用來自細菌的光,

  • to counter-illuminate itself in an anti-predation device

    當成是牠匿蹤裝置中,模擬背景光線的來源,

  • so predators can't see its shadow,

    因此獵食者無法看見牠的陰影,

  • calculate its trajectory, and eat it.

    計算牠的動向,然後吃了牠。

  • This is like the stealth bomber of the ocean.

    就像是大海中的隱形轟炸機一般。

  • (Laughter)

    (笑聲)

  • But then if you think about it, the squid has this terrible problem

    但是如果你深入去思考,這烏賊會有一個可怕的問題,

  • because it's got this dying, thick culture of bacteria

    因為在牠體內,這些黏稠的細菌液正在逐漸死亡,

  • and it can't sustain that.

    牠無法維持這些細菌的生長。

  • And so what happens is every morning when the sun comes up

    因此每天早上當太陽升起後,

  • the squid goes back to sleep, it buries itself in the sand,

    牠將自己埋藏在沙中,進入睡眠,

  • and it's got a pump that's attached to its circadian rhythm,

    而且牠有一個與日夜週期同步的幫浦,

  • and when the sun comes up it pumps out like 95 percent of the bacteria.

    當太陽升起時,它將大約 95% 的細菌排出體外。

  • Now the bacteria are dilute, that little hormone molecule is gone,

    既然細菌被稀釋了,這些小荷爾蒙分子也隨之消失,

  • so they're not making light --

    因此牠們不發光了,

  • but of course the squid doesn't care. It's asleep in the sand.

    但烏賊當然不在意。牠正在沙中睡覺呢。

  • And as the day goes by the bacteria double,

    當一天過去,這些細菌持續分裂生長,

  • they release the molecule, and then light comes on

    牠們釋放出這些分子,然後又開始在晚上發光,

  • at night, exactly when the squid wants it.

    剛好就是烏賊需要光線的時候。

  • First we figured out how this bacterium does this,

    我們先瞭解這些細菌為什麼會有這種現象,

  • but then we brought the tools of molecular biology to this

    然後我們使用分子生物學的方法來研究

  • to figure out really what's the mechanism.

    這個現象下,真正的分子機制為何?

  • And what we found -- so this is now supposed to be, again, my bacterial cell --

    我們發現了 — 再一次,想像這是我的細菌 —

  • is that Vibrio fischeri has a protein --

    費氏弧菌有一種蛋白質

  • that's the red box -- it's an enzyme that makes

    這個紅色的方塊 — 它是製造這

  • that little hormone molecule, the red triangle.

    小荷爾蒙分子(紅三角形)的酵素。

  • And then as the cells grow, they're all releasing that molecule

    當細胞生長時,他們全都釋放這個分子

  • into the environment, so there's lots of molecule there.

    到環境中,因此環境裡有一堆這種分子。

  • And the bacteria also have a receptor on their cell surface

    這些細菌的細胞表面,同時還有一種受器,

  • that fits like a lock and key with that molecule.

    與此分子的構造就如同鑰匙與鎖一般的吻合。

  • These are just like the receptors on the surfaces of your cells.

    它們就如同你身體細胞表面上的受器一般。

  • When the molecule increases to a certain amount --

    當這些分子增加到一定的量時 —

  • which says something about the number of cells --

    它也意味著這些細胞數量的增加 —

  • it locks down into that receptor

    荷爾蒙與受器相結合,

  • and information comes into the cells

    訊息開始向細胞內部傳遞,

  • that tells the cells to turn on

    這個訊息告訴這些細胞開始

  • this collective behavior of making light.

    表現此集體行為,並開始發光。

  • Why this is interesting is because in the past decade

    這個發現之所以有趣,是因為在過去十年間,

  • we have found that this is not just some anomaly

    我們發現這個現象,不只侷限在這些住在大海中,

  • of this ridiculous, glow-in-the-dark bacterium that lives in the ocean --

    滑稽的、會在黑暗中發光的細菌,

  • all bacteria have systems like this.

    所以的細菌都有類似的系統。

  • So now what we understand is that all bacteria can talk to each other.

    所以現在,我們了解所有細菌都可以彼此交談。

  • They make chemical words, they recognize those words,

    它們製造化學文字,也能夠辨認這些文字,

  • and they turn on group behaviors

    然後表現集體行為,

  • that are only successful when all of the cells participate in unison.

    只有當所有細胞一起同心協力才能成功。

  • We have a fancy name for this: we call it quorum sensing.

    我們為這種行為取了一個新潮的名字,稱作:聚量感應。

  • They vote with these chemical votes,

    取決於這些化學物質的數量

  • the vote gets counted, and then everybody responds to the vote.

    加以統計後,所有細胞都要服從最後的結果。

  • What's important for today's talk

    今天演講最重要的一點是

  • is that we know that there are hundreds of behaviors

    我們已經知道有數百種以上的

  • that bacteria carry out in these collective fashions.

    這種細菌的集體行為。

  • But the one that's probably the most important to you is virulence.

    但對你們來說,最關心的應該還是致病性的問題。

  • It's not like a couple bacteria get in you

    並不是說一些細菌進入你體內後

  • and they start secreting some toxins --

    就馬上開始分泌致病毒素,

  • you're enormous, that would have no effect on you. You're huge.

    相對它們來說非常巨大,這點量對你不會有太大的影響。

  • What they do, we now understand,

    我們現在了解,它們是

  • is they get in you, they wait, they start growing,

    先進入你的身體,等待,開始複製成長,

  • they count themselves with these little molecules,

    它們藉由計算這些小分子的數目來估計自身的數量,

  • and they recognize when they have the right cell number

    直到確定有足夠的細胞數為止,

  • that if all of the bacteria launch their virulence attack together,

    一旦這些細菌一起發動致病攻擊,

  • they are going to be successful at overcoming an enormous host.

    它們就能成功攻陷巨大的宿主。

  • Bacteria always control pathogenicity with quorum sensing.

    細菌一向是以「聚量感應」來控制其致病性。

  • That's how it works.

    這就是它們運作的原理。

  • We also then went to look at what are these molecules --

    我們同時也研究了這些分子,

  • these were the red triangles on my slides before.

    這些就是我之前投影片上的小紅三角形。

  • This is the Vibrio fischeri molecule.

    這個是費氏弧菌的分子。

  • This is the word that it talks with.

    這就是它們用以交談的文字。

  • So then we started to look at other bacteria,

    我們開始研究其他細菌,

  • and these are just a smattering of the molecules that we've discovered.

    這些是我們已發現分子中的一小部份。

  • What I hope you can see

    我希望你們看得出來

  • is that the molecules are related.

    這些分子之間是有關聯性的。

  • The left-hand part of the molecule is identical

    就算是不同的菌種

  • in every single species of bacteria.

    它們分子的左半部都是相同的

  • But the right-hand part of the molecule is a little bit different in every single species.

    但是右半部則因不同的菌種而有些許的不同。

  • What that does is to confer

    這個發現證實了

  • exquisite species specificities to these languages.

    細菌的語言有高度的專一性。

  • Each molecule fits into its partner receptor and no other.

    每一種分子只能與其相對受器結合,非常專一。

  • So these are private, secret conversations.

    所以這些交談是私下的、秘密的

  • These conversations are for intraspecies communication.

    只給同種族內溝通交流。

  • Each bacteria uses a particular molecule that's its language

    每一種細菌使用一種特殊分子代表它的語言,

  • that allows it to count its own siblings.

    讓它能夠計算同類的數量。

  • Once we got that far we thought

    一旦我們了解這些,

  • we were starting to understand that bacteria have these social behaviors.

    我們也開始了解細菌有所謂的社交行為。

  • But what we were really thinking about is that most of the time

    但我們真正思考的問題是,多數時間裡,

  • bacteria don't live by themselves, they live in incredible mixtures,

    細菌並不是單獨生活的,它們居住的地方龍蛇雜處,

  • with hundreds or thousands of other species of bacteria.

    跟其它千百種以上的細菌同處一室。

  • And that's depicted on this slide. This is your skin.

    這張投影片說明了這個情形。這是你的皮膚。

  • So this is just a picture -- a micrograph of your skin.

    這只是一張照片,你皮膚的顯微照片。

  • Anywhere on your body, it looks pretty much like this,

    不論在你身體何處,看起來差不多就是這個樣子,

  • and what I hope you can see is that there's all kinds of bacteria there.

    我希望你能看出,這裡有各種不同的細菌。

  • And so we started to think if this really is about communication in bacteria,

    因此我們開始思考,這會不會也跟細菌間的溝通有關,

  • and it's about counting your neighbors,

    跟計算你鄰居的數量有關,

  • it's not enough to be able to only talk within your species.

    只跟自己人溝通是不夠的

  • There has to be a way to take a census

    它們一定有某種方法

  • of the rest of the bacteria in the population.

    能跟其他種細菌達成共識。

  • So we went back to molecular biology

    所以我們回到分子生物學的領域,

  • and started studying different bacteria,

    開始研究不同的細菌,

  • and what we've found now is that

    我們現在已經發現,

  • in fact, bacteria are multilingual.

    事實上,細菌可以講很多種語言。

  • They all have a species-specific system --

    它們都有一個菌種專一的系統,

  • they have a molecule that says "me."

    並用特定分子來辨別同類

  • But then, running in parallel to that is a second system

    但是,我們已經發現,它們同時還有第二種系統,

  • that we've discovered, that's generic.

    那是一個通用的系統。

  • So, they have a second enzyme that makes a second signal

    因此,它們有另一個酵素能產生第二種訊號,

  • and it has its own receptor,

    這訊號也有自己的受器,

  • and this molecule is the trade language of bacteria.

    這個分子是細菌們的貿易語言。