Name: TED-Ed】獨角羊的怪事--阮天佑。 (【TED-Ed】The strange case of the cyclops sheep - Tien Nguyen)
Uploaded: 2021-01-14T07:06:03.000Z
Duration: 4 min 41 s
Description: 【看影片學英語】數萬部 YouTube 影片，搭配英漢字典即點即查，輕鬆掌握單字發音與用法，長久累積看電影不必再看字幕。

In the 1950s, a group of ranchers in Idaho

were baffled when their sheep gave birth to lambs with a singular deformity.

they called in scientists from the U.S. Department of Agriculture to investigate.

The researchers hypothesized that the pregnant ewes

had snacked on poisonous  birth defect-causing plants.

They collected the local flora and fed samples to lab rats,

So they decided  to directly observe the sheep

with one scientist even living with the herd for three summers.

After a decade of trial and error, the scientists finally found the culprit,

The lilies contained an active molecule with six connected rings

that they named cyclopamine in reference to the cyclops sheep.

They didn't know exactly how cyclopamine caused the defect

It took about four decades before a team of biologists,

His lab was studying a specific gene found in many species,

It was named by two scientists, who later shared the Noble Prize for their work,

who found that mutating  this gene in fruit flies

Beachy and his colleagues performed genetic modifications

This resulted in severe defects  in the development

Then while perusing a textbook, Beachy  came across photos of the cyclops sheep

and realized what had eluded scientists for four decades.

Something must have gone awry  involving the hedgehog gene.

Genes contain instructions that tell cells what to do and when to do it,

and they communicate their directives using proteins.

The hedgehog gene itself tells cells to release a so-called hedgehog protein,

which kicks off a complex  series of cellular signals.

Here's how it works in normal healthy development.

Hedgehog protein latches on to a protein called patched.

allowing another protein called smoothened to freely signal the cells,

telling them where to go and what kind of tissues to become.

Cyclopamine, say in the form  of a delicious corn lily,

interrupts this pathway by binding onto smoothened.

That locks smoothened up so that it's unable to send the signals

needed to mold the brain  into two hemispheres,

So even though the hedgehog protein is still doing its job

cyclopamine blocks smoothened from passing along its chemical message.

That settled the science behind the one-eyed sheep,

but Beachy and his team  caught the glimmer

They noted that uncontrolled activation of the smoothened protein

It's known as Basal Cell Nevus Syndrome, and it predisposes people to certain cancers.

putting cyclopamine's smoothened  binding powers to good use

Unfortunately, researchers eventually found that cyclopamine

and its chemical properties make it difficult to work with.

But they did discover that closely related molecules are safe and effective,

and two of these drugs were approved in 2012 and 2015 as skin cancer medicines.

When those farmers first saw the cyclops sheep,

they could have chalked it up to a freak genetic mutation and walked away.

Instead, their decision to investigate turned a mystery into medicine

showing that sometimes there's more than meets the eye.

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TED-Ed】獨角羊的怪事--阮天佑。 (【TED-Ed】The strange case of the cyclops sheep - Tien Nguyen)

struggle

negative

culprit

effective