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Transgenic Salmon

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基因与人类（从行为到生物技术）

马里兰大学帕克分校

4.6（469 个评分） | 37K 名学生已注册

To acquire an understanding of the fundamental concepts of genomics and biotechnology, and their implications for human biology, evolution, medicine, social policy and individual life path choices in the 21st century.

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您将学习的技能

Biology, Human Genetics, Genetics, Evolution

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4.6（469 个评分）

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GL

May 31, 2017

Really interesting material and well taught, even entertaining at times! :0) The quizzes were detailed but not excessively hard, and did a good job of assessing if you had learning the material.

SP

May 01, 2018

This course is great for someone who wants to learn the impact biotechnology has made in our lives and it's future prospects. The concepts covered in the course have been explained very well.

从本节课中

The Future is Now

Module Six discusses the history of biotechnology, its role in our lives today, and its prospects for the future.

Early Transgenic Technologies12:02

Spider Goats11:54

Transgenic Salmon11:57

Golden Rice12:02

Synthetic Biology13:53

Bio-Hacking13:25

Pre-Implantation Genetic Diagnosis12:43

教学方

Raymond J. St. Leger
Professor
Tammatha O'Brien
Lecturer

脚本

[MUSIC]

Welcome back.

Well, for the most part, genetically modified goats

that express spider silk don't get people riled up.

What really riles people up is transgenic food.

A prospect of eating someone's science experiment turns the

stomach of someone who aspires to all natural foods.

As if Aberdeen Angus beef, corn, and beef

steak tomatoes were the product of unfettered natural selection.

So let's have a look at the

controversy regarding genetic engineering of agricultural products.

The usual critisisms of Biotech crops is

that they're untested, they hasten environmental degradation, they

result in unstoppable super weeds, they pose

health threats, and they increase dangerous pesticide usage.

And that they could unleash unpredictable

Frankenstein-like creatures onto the world ecosystem.

These allegations, often fueled by anti-Americanism

and fears of corporations such as Monsanto,

have taken a grip on the European psyche.

In a recent YouGov poll, only 21% of British people supported GM technology.

While 35% opposed it.

The people who produce the food are largely in favor however.

A Farmer's Weekly survey found that 61% of

farmers would grow transgenic crops if they could.

European fears regarding transgenic crops are for

the most part stuck in the 20th century.

They're alarmists,

based on worse case scenarios. They're not based on evidence.

As they're heedless of the latest science.

In fact all the allegations made against

transgenic crops have been demonstrated to be

untrue, of exaggerations of problems that are

present in all of agriculture, including organic farming.

But if resistance to biotechnology is idealogical, then it's

going to be hard to contest those views with evidence.

The satirist Jonathan Swift told us that it's not possible

to reason someone out of a position, that they didn't themselves into.

That's unfortunate, because there's an enormous amount of evidence to go on.

Critics of biotech often assert that the

science just hasn't been done on transgenic crops.

In fact, as the European Commission itself found

in a 2010 survey of hundreds of scientfic

studies, there's simply no evidence that transgenic crops

put the health of humans or the environment

at increased risk.

Overwhelmingly other independent surveys show the same

thing, according to one estimate two trillion

meals containing genetically modified food have been

consumed in the two years up to 2011.

Conversely, there is abundant evidence that a

big increase in food production will be needed

in the next three decades, and that transgenic

crops will have to be part of it.

Over the last 60 years agricultural production has grown in large

part through irrigation and chemical

additives, such as fertilizers and pesticides.

But as the world population continues to soar, even with

these technologies, agriculture struggled to keep pace with the world's needs.

And more than a billion people already go hungry every day.

The world's population, now about 7 billion,

is expected to hit 9 billion in 2050.

So scientists must find ways of feeding an

extra 3 billion by the middle of the century.

Means we'll have to produce more food in the next 40 years than we've had to for

the past 8,000 years when agriculture began And we

must do this in spite of incoming climate change.

We're on track to convert more and more wild lands, including rain-forests and

savanna, to cropland.

Already 40% of the planet's land surface is used for agriculture.

To interupt the flow of wholesale land conversion,

while needing to produce about 60% more food.

Is going to require something quite extraordinary.

Transgenic crops and potentially synthetic biology

can greatly increase yields, providing more

food per acre, which reduces the amount of land that must be u,

used for agriculture.

Greater yields that are necessary to feed the world's population.

I'll give you an example of what could be achieved.

Ultimately all of our food, indeed all life on earth relies on

the conversion of carbon dioxide into

sugars by photosynthesis using the Sun's energy.

Most crops use a chemical pathway to photosynthesis that

binds three carbon atoms from the air, it's called the

C3 pathway.

But around 5% of plants have evolved

a different pathway that binds four carbon atoms.

The C4 pathway, is not only more efficient at warmer

temperatures, it also uses less fertilizer and less water during photosynthesis.

So C4 pathway is ideal for the hotter drought

conditions that are increasingly prevalent, owing to climate change.

C4 plants are so successful,

especially in tropical savannas, that they are responsible for as much as 30% of

all terrestrial carbon fixing, even though they make up 5% of plants.

Now, some of the crops that we cultivate use the

C4 pathway, including corn, and sugar cane, sorghum, and millet.

But many of the most popular crops, including wheat and rice, are C3 plants.

Their yields suffer in hotter, drier conditions,

just where and when we need to increase them.

So scientists are now genetically manipulating

C3 crops to turn them into C4s.

Researchers have begun with rice, are changing its leaf

anatomy to that of a C4 plant which are closely

at veins of two cell types, and switching the bio-chemical

make up of enzymes and proteins to the C4 type.

Once they achieve this with rice it'll be

fairly to convert other crops such as wheat, barley

and rape seed.

A successful crop conversion like this would have a profound

impact on our lives and make agriculture much more efficient.

Reducing global land use change it also

means fewer reservoirs and river diversions for irrigation.

Currently 70% of our fresh water use goes on agriculture.

Or rearranging how plants photosynthesize may seem

radical to you, but it, but we shall

see in a later lecture, that some scientists working in the field

of synthetic biology were able to get rid of conventional agriculture all together.

Well the biggest hold in the application of

biotechnology today is not it's usefulness, but politics.

Many researchers and science journalists believe that the

opponents of biotechnology are today focusing on teaching the

controversy, in a similar fashion as evolution and climate

change deniers, even though there's very little controversy remaining.

Nevertheless, anti-biotech campaigners run a carefully orchestrated

campaigns of opposition and frighten people and many

politicians inclined to take the easiest and least

controversial paths and bow to noisy interest groups.

And it's damaging the prospects of

applying technology that would have major benefits.

So let's look two cases where political considerations

that wanted use of two potentially very valuable products.

One animal, and the other a plant.

The animal is salmon.

Global wild fisheries are in decline with

valuable habitats such as estuaries in critical condition.

Fisheries, fished to their limits means they are getting

much more food from natural habitats may not be possible.

Increasing human demand for animal protein has meant relying on aquaculture.

That is using ponds, nets, and pens for growing fish.

Aquaculture is consequently on the

crest of a wave.

Being the fastest growing food sector in the world.

In 2012, [UNKNOWN] and fish farming reached 66 million

tons, while wheat production was down to 63 million.

It's calculated by the, by 2015 humans will eat more farmed than wild fish.

It would benefit aquaculture to have fish grow

faster and feed more efficiently so they cost less.

AquaBounty, a Massachusets

biotech company, may be the most patient company on the planet.

In 1993 the company approached the Food and Drug Administration about

selling a genetically modified salmon that grew faster than normal fish.

That AquaAdvantage fish is an Atlantic salmon

that carries two foreign bits of DNA.

A growth hormone gene from the Chinook salmon

that is under the control of the promoter.

The on/off switch from the ocean pout, which, an eel-like fish that

lives in the chilly deep.

That's in the context now for salmon's 25,000 genes.

When normally Atlantic salmon produce growth

hormone only in the warm summer months.

These genetic adjustments let the fish churn it out year-round.

As a result, the AquaAdvantage salmon typically reach their adult

size in a year and a half, rather than three years.

That three year figure refers to varieties whose growth rate has already

been improved two-fold as a result of traditional selective breeding.

These two fish are of the same age.

The small one is the best selective breeding has so

far achieved, and the big one is the AquaAdvantage salmon.

The difference is not a subtle one.

What is worse, genetic engineering making this heart healthy fish more

affordable for consumers, and taking the strain off of wild fish stocks.

They are to convert their food to body weight much more efficiently.

Meaning that less food makes a bigger fish.

That would alleviate a particular problem with salmon,

which is that they themselves eat fish, and so

get fed a, a lot of high protein fish meal, which could also be fed to people.

Well, quicker growing time and less feed

would also mean less pollution from fish farming.

If the modified fish is approved,

it'll be the first transgenic animal to officially enter the human food supply.

Appropriately, it's been subject to rigorous review, with scientists

all over the country weighing in on whether it

is fit for human consumption and what might happen

if it was to make its way into the world.

Scientists, including the FDA's experts, have concluded

the fish is just as safe to eat

as conventional salmon The Atlantic Salmon Federation, however,

fears the fish could get into the wild.

Start breeding and disturb the ecosystem.

Well, according to Aqua Bounty, the engineered salmon are all female,

sterile, and raised in physically constrained

facilities, as shown in this figure.

So the chance of the fish breeding in the wild is negligible.

Well, in an opinion piece in the New York Times, science journalist Emily Anthes

describes how politics, not science, has slowed

the approval process for AquaAdvantage's genetically modified salmon.

The article mentions the genetic literacy project, GLP.

And it's Executive Director Jon Entine, who revealed that the Obama White House

intentionally delayed the approval process for

the salmon until after the last election.

Many of the members of Congress who opposed the

modified fish represent states with strong salmon in, in, industries.

And some non-profit groups seem to be opposing the modified salmon reflexively.

As part

of an agenda to oppose all animal

biotechnology, regardless of its safety or potential benefits.

Well, now the FDA has extended the deadline for the public to comment on

the salmon, further delaying its decision, which so far taken two decades to reach.

It's not clear that these salmon will ever get to market.

Well, fortunately, the salmon project has had beneficial knock on effects

in triggering a series of several modification programs that have at,

obtained dramatic growth enhancement. Vegetarian fish such

as carp and tilapias, which are the most important fish used in aqua farming.

Particularly in the developing world

where 90% of fish farming takes place.

[NOISE]

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