You smell with your body, not just your nose | Jennifer Pluznick

翻译人员: Chao Peng 校对人员: Qing Ying Sun

Here's a question for you:

请先思考一个问题：

how many different scents do you think you can smell,

你认为自己可以分别多少种不同的气味？

and maybe even identify with accuracy?

或者精确地识别多少种？

100?

100种？

300?

300种？

1,000?

还是1000种？

One study estimates that humans can detect up to one trillion different odors.

一项研究估计人类可以识别 多达一万亿种不同的味道。

A trillion.

一万亿种。

It's hard to imagine,

这很难想象，

but your nose has the molecular machinery to make it happen.

但是你的鼻子的分子机制 让它成为了现实。

Olfactory receptors --

嗅觉受体，

tiny scent detectors --

你的鼻子里

are packed into your nose,

充满了微小的气味检测器，

each one patiently waiting to be activated by the odor,

每一个都耐心地等待被气味激活，

or ligand,

换句话说，

that it's been assigned to detect.

被指定来探测配位体。

It turns out we humans, like all vertebrates,

其实我们人类和所有的脊椎动物一样

have lots of olfactory receptors.

有许许多多的气味受体。

In fact, more of our DNA is devoted to genes for different olfactory receptors

事实上，我们的DNA中被用来 表达气味受体的基因多于

than for any other type of protein.

任何一种用于制造其它蛋白质的基因。

Why is that?

为什么会这样？

Could olfactory receptors be doing something else

气味受体除了给我们嗅觉

in addition to allowing us to smell?

还有其它的功能吗？

In 1991, Linda Buck and Richard Axel uncovered the molecular identity

在1991年，琳达·巴克和理查德·阿克塞尔 揭示了气味受体的

of olfactory receptors --

分子识别机制。

work which ultimately led to a Nobel Prize.

这一成果最终获得了诺贝尔奖。

At the time,

在那时，

we all assumed that these receptors were only found in the nose.

我们都设想这些气味受体 都只能在鼻子里被发现。

However, about a year or so later,

然而，大约一年以后，

a report emerged of an olfactory receptor expressed in a tissue

一份报告指出气味受体 也存在于不是鼻子的

other than the nose.

另一组织里。

And then another such report emerged,

然后另一份这样的报告也出现了，

and another.

接着又是一份。

We now know that these receptors are found all over the body,

现在我们知道在我们身体的每一处 都可以找到这些气味受体，

including in some pretty unexpected places --

包括一些意想不到的部位——

in muscle,

肌肉组织，

in kidneys,

肾脏，

lungs

肺部，

and blood vessels.

以及血管。

But what are they doing there?

但是它们为什么存在于那些部位？

Well, we know that olfactory receptors act as sensitive chemical sensors

我们知道气味受体在鼻子中 扮演一种敏感的

in the nose --

化学传感器的角色——

that's how they mediate our sense of smell.

这是它们传出嗅觉（信号）的方法。

It turns out they also act as sensitive chemical sensors

其实它们也在我们 身体的许多其它部位

in many other parts of the body.

扮演灵敏的化学传感器的角色。

Now, I'm not saying that your liver can detect the aroma of your morning coffee

当然，我不是在说你的肝脏 可以在你走进厨房的时候

as you walk into the kitchen.

闻出早晨的咖啡香气。

Rather, after you drink your morning coffee,

而是当你喝过早餐咖啡后，

your liver might use an olfactory receptor

你的肝脏可能使用一个气味受体

to chemically detect the change in concentration

通过化学机制检查在你血液中流动的

of a chemical floating through your bloodstream.

化学物质浓度的变化。

Many cell types and tissues in the body use chemical sensors,

身体中的许多细胞种类和身体组织使用

or chemosensors,

化学感应器，

to keep track of the concentration of hormones, metabolites

来追踪激素和代谢物

and other molecules,

以及其它分子的浓度。

and some of these chemosensors are olfactory receptors.

这些化学感应器中的 一部分就是气味受体。

If you are a pancreas or a kidney

如果你是一个胰腺或者肾脏，

and you need a specialized chemical sensor

而当你需要一个特殊的可以帮助你

that will allow you to keep track of a specific molecule,

追踪某个特定分子的 化学传感器的时候，

why reinvent the wheel?

为什么要白费力气做重复工作呢？

One of the first examples

最早在鼻子以外

of an olfactory receptor found outside the nose

发现气味受体的其中一个例子

showed that human sperm express an olfactory receptor,

告诉我们人类的精子 就恰恰配备了气味受体，

and that sperm with this receptor will seek out the chemical

拥有了这个受体， 精子可以寻找一种化学物质，

that the receptor responds to --

即令这种受体做出反应的化学物质，

the receptor's ligand.

也就是受体的配位体。

That is, the sperm will swim toward the ligand.

也就是说，精子会游向这个配位体。

This has intriguing implications.

这里有一个有趣的暗示。

Are sperm aided in finding the egg

精子寻找卵子的过程当中

by sniffing out the area with the highest ligand concentration?

是否是靠嗅探拥有 最高配位体浓度的区域呢？

I like this example because it clearly demonstrates

我喜欢这个例子因为它清晰地说明了

that an olfactory receptor's primary job is to be a chemical sensor,

一个气味受体的首要工作是 做一个化学传感器，

but depending on the context,

但是结合情境，

它还可以影响你感受气味，

it can influence how you perceive a smell,

or in which direction sperm will swim,

或者引导精子游向的方向。

and as it turns out,

而且事实上，

a huge variety of other processes.

还拥有各种各样的功能。

Olfactory receptors have been implicated in muscle cell migration,

气味受体帮助肌肉细胞的移动，

in helping the lung to sense and respond to inhaled chemicals,

帮助肺部感应和回应吸入的化学物质，

and in wound healing.

以及手部创伤的痊愈。

Similarly, taste receptors once thought to be found only in the tongue,

同样的，味觉受体曾经 被认为只存在与舌头中，

are now known to be expressed in cells and tissues throughout the body.

现在我们知道它们存在于 身体各处的细胞和组织中。

Even more surprisingly,

更令人惊奇的是，

a recent study found

最近的一个研究表明

that the light receptors in our eyes also play a role in our blood vessels.

眼睛中的光受体在血管中 居然也能发挥某种功能。

In my lab,

在我的实验室里，

we work on trying to understand the roles of olfactory receptors and taste receptors

我们致力于尝试推断 气味受体和味觉受体

in the context of the kidney.

在肾脏中的功能。

The kidney is a central control center for homeostasis.

肾脏在体内平衡中扮演着核心角色。

And to us,

对于我们来说，

it makes sense that a homeostatic control center would be a logical place

作为体内平衡的核心控制器的 部位拥有化学传感器

to employ chemical sensors.

是完全合乎情理的。

We've identified a number of different olfactory and taste receptors

我们已经在肾脏中识别出许多不同的

in the kidney,

气味受体和味觉受体。

one of which, olfactory receptor 78,

其中之一，气味受体78号

is known to be expressed in cells and tissues

据了解已经存在于

that are important in the regulation of blood pressure.

重要的控制血压的细胞和组织中。

When this receptor is deleted in mice,

当我们在老鼠体内清除这种受体时，

their blood pressure is low.

它们的血压会变低。

Surprisingly, this receptor was found to respond

令人惊奇的是，这些受体 曾被发现是用来回应

to chemicals called short-chain fatty acids

一种被称作短链脂肪酸的化学物质。

that are produced by the bacteria that reside in your gut --

这种物质由肠道中的一种细菌产生——

your gut microbiota.

具体地说是肠道菌群。

After being produced by your gut microbiota,

这些化学物质在被肠道菌群产生后

these chemicals are absorbed into your bloodstream

直接被体内循环的血液吸收。

where they can then interact with receptors

在血液里它们与受体发生反应，

like olfactory receptor 78,

比如气味受体78号，

meaning that the changes in metabolism of your gut microbiota

也就是说，你的 肠道菌群的新陈代谢的变化

may influence your blood pressure.

可能会影响你的血压。

Although we've identified a number of different olfactory and taste receptors

尽管我们已经在肾脏中 识别出了许多不同的气味受体和

in the kidney,

味觉受体，

我们还是刚开始梳理它们不同的功能，

we've only just begun to tease out their different functions

and to figure out which chemicals each of them responds to.

以及它们分别会对 哪些化学物质做出回应。

Similar investigations lie ahead for many other organs and tissues --

类似的针对其它器官 和组织的调查研究即将开展——

only a small minority of receptors has been studied to date.

迄今为止人们仅仅 研究了很小一部分受体。

This is exciting stuff.

这是一件令人激动的事。

It's revolutionizing our understanding of the scope of influence

它对我们理解人类五感之一的 作用范围有着

for one of the five senses.

革命性的影响。

And it has the potential to change our understanding

而且它具有巨大的潜质来改变我们对于

of some aspects of human physiology.

人类生理机能的某些方面的理解。

It's still early,

尽管这项研究尚未成熟，

but I think we've picked up on the scent of something we're following.

但是我相信我们嗅到了 一种寻觅已久的气味。

(Laughter)

（笑声）

Thank you.

谢谢大家。

（掌声）

(Applause)