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(lively piano music)
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Downloaded from
YTS.MX
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- [Voiceover] Our hands,
our eyes, our face,
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Official YIFY movies site:
YTS.MX
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our whole body is a swarm
of billions of cells.
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At the heart of each
of them nestles the DNA
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we received from our parents
and pass on to our children.
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- What exactly is transmitted
from one generation
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to the next, from one cell to the next?
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We know that DNA is
transmitted, but not only DNA.
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- [Voiceover] Identical
twins have the same DNA,
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the same genome, yet they're
physically different.
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How is this possible?
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- And then we view the genome as a book
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then it can be read in
many different ways.
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- [Voiceover] Scientists have
long thought that DNA alone
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ruled our biological destiny.
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Today, they're discovering another world.
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- We've become more
and more aware that DNA
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doesn't explain everything
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and more and more capable of integrating
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the ideas about the
impact of the environment.
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- [Voiceover] All over the world,
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Biologists are exploring this new mystery.
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- My work consists in
looking at the heart of cells
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of new knowledge and going
where no one has been before.
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- [Voiceover] A scientific
adventure where the researchers
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are gradually discovering
what influences our DNA
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throughout our lives, our identity,
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and perhaps our heredity.
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(lively piano music)
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(bright music)
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In the natural world,
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one insect has always fascinated, the bee.
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Its destiny never ceases
to amaze and puzzle
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the specialists.
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They are gradually elucidating
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the mysteries of its development.
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(calm music)
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There are hundreds of
species of bees in existence
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including this one, the domestic bee,
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which lives in a highly organized society.
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- I'm standing in front
of a colony of bees.
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A colony of bees means a
large number of workers,
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maybe 20, 30, or 40,000.
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And there's just one queen,
the mother of all those bees.
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You can see the queen here.
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She has a dot of red paint on the thorax
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put there by the bee keeper
to help him find her.
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Although she's quite clearly different
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from the other bees around her,
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she doesn't have the
same shape, she's longer.
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You can also see that her
thorax is slightly larger.
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The queen's distinctive
feature is fertility.
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She's the only one able to mate,
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so her job is to lay eggs.
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(calm music)
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- [Voiceover] A queen is
therefore very different
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from the other workers in her colony,
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and yet in the very first
days of their lives,
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the queen's larvae and the
worker's larvae are identical.
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How is it that occasionally
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one of them steps from the ranks?
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(calm music)
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It wasn't until the 1950s
that this mysterious process
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was understood.
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- What makes one larva a
queen rather than a worker
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is largely explained by what it eats.
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A larva eats royal jelly for three days
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and then if it is destined
to become a worker,
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its food will be changed
and the royal jelly
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will progressively be
mixed with larval mush
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that contains honey and pollen.
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The queen larva, however,
will continue to eat
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royal jelly for the rest
of its time as a larva.
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(buzzing)
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- [Voiceover] Thus, a
simple change in diet
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can cause profound differences between
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two living beings that were so similar
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when they started out their lives.
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But how can you explain that
an external element can have
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such an impact on their growth?
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Isn't that supposed to
be governed by their DNA?
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To understand this process,
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you have to go back to the origins
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or one of biology's most fascinating
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scientific adventures, the
sequencing of the human genome.
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(calm music)
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We have long sought to
understand the laws of heredity
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and the way character is transmitted
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from one generation to another.
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In the mid-20th century,
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we discovered that DNA was
the medium of heredity.
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In humans, at the heart of a cell,
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the nucleus, are 23 pairs of chromosomes.
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Each chromosome is made
up of two strands of DNA.
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Composed of four bases
represented by the letters
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A, T, G, C, the DNA of a human being
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contains three billion letters
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which assemble themselves
into phrases to form genes.
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The genes are used to make the proteins
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which make up the building
block of living organisms.
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In the early 2000s, the
sequencing of the human genome
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with straws of detailed map of over 25,000
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genes was completed.
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It was a significant
scientific breakthrough
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and hopes were high.
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(questing music)
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- Today, we celebrate the revelation
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of the first draft of
the human book of life.
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- [Voiceover] Scientific
journals published the genome map
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with pride of place of being
given to the almighty gene.
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Genome sequencing raised
the wildest expectations.
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Genes for obesity and
schizophrenia will be discovered.
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Cancer will be eradicated.
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The promises of science seemed endless.
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- We are probably, as
scientists, a little bit to blame
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that we told everybody
how important DNA was.
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- We said we have
deciphered the human genome.
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Decipher means taking an encrypted message
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and making it intelligible.
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But we read the genome
and understood nothing.
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The actual deciphering
is what we do afterwards
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what we've not finished doing
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and it'll take some time.
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- [Voiceover] The
scientists know they're only
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at the start of the adventure.
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They have in their hands a text
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that is difficult to interpret.
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- DNA is not the only critical thing.
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We cannot explain
everything just by looking
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at DNA sequence.
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We need it to know what the sequence is,
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but biological complexity
and biological systems
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are not just about DNA.
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They're about the way DNA is used,
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the way DNA is read, the
way DNA is transmitted.
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- [Voiceover] A few months
after the announcement
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of the sequencing of the human genome,
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the review Science for the first time
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devoted an entire issue to epigenetics,
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a new scientific field that
explores what influences
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the expression of DNA
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for there are too many
questions unanswered.
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- People were searching for something else
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that might explain the beauty,
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the complexity of who we are.
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- [Voiceover] In Australia,
researchers are striving
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to understand the fate of bees.
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Their genome has just
been entirely sequenced.
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And there's a big surprise.
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There is no genetic
difference between the larvae
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of a worker bee and a larvae of a queen.
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They share the same DNA.
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So if the difference between
larvae is not genetic,
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perhaps it's epigenetic.
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Might this famous royal
jelly be able to influence
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bee larvae genes to the
point where it can turn them
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into a queen?
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The process begins at a larval stage.
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After three days, worker
larva and queen larva
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are no longer fed in the same way.
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It's a change that profoundly
alters their development.
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- Here, we see that they metamorphosed
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at different rates.
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The queens grow faster than the workers.
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After around two weeks here,
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a queen is ready to emerge,
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whereas a worker will take three weeks.
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- [Voiceover] So it is
the feed, the royal jelly,
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which makes the difference.
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But how does it act on
the the larva genes?
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- In chemical terms what happens
is an epigenetic mechanism.
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The methylation of the DNA which triggers
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these various growth programs.
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- [Voiceover] Bee DNA
contains around 10,000 genes.
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As with all living organisms,
some genes are active
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or expressed as they
say, others are inactive.
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The expression of genes can be inactivated
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by what is called the
methylation of the DNA.
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It's a simple chemical mark
that attaches itself to the gene
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and in a way enables it to be turned off
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like a switch.
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- If there's a lot of DNA
methylation during early growth
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then you'll get workers,
whereas if the DNA methylation
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is turned off then you get queens.
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In the same way that food activates
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a certain epigenetic program that enables
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either queens or workers to be created,
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here we're injecting
molecules into these eggs
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to stop DNA methylation.
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And so, all these eggs
will grow into queens.
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- [Voiceover] Thus is the
amazing recipe for making queens
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revealed to us.
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There is no queen DNA nor worker DNA,
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just chemical modifications
around their genes
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which play a key role in their growth.
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This applies to bees,
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does it also apply to other
species, other queens?
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Jonathan Weitzman has his
own ideas on the matter.
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- Another example from nature,
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I'm British, to the left is our queen,
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queen by birth, so we can
say she's a genetic queen.
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To the right are the bees
who have just one queen
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but she's not born to be queen.
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In time, one of the bees becomes a queen
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because she eats royal jelly.
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So you can see in England,
there are two ways
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of becoming a queen, either
genetically on the left
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or by interaction with your environment,
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you can, in a few rare
cases, become a queen.
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(laughter)
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- [Voiceover] What are we made of?
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Who are we?
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Whether it's a matter
of scientists or cells,
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DNA doesn't explain all
the diversity of life.
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Cells from our liver, our eye, or our hand
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all have the same genome.
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And yet they're almost as
varied as the researchers.
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So how do you explain such diversity?
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(applauding)
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This question fascinates
Jonathan Weitzman.
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He explores the issue of
identity starting with that
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of ourselves.
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- In our body we have hundreds
of different cell types,
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cells that behave
differently to have different
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characteristics, and they
transmit those different
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characteristics to their daughter cells.
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The hepatocytes in the liver,
the neurons in the brain,
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the lymphocytes in the blood,
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the keratinocytes in the skin,
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all these cells are behaved differently.
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They use the genome differently.
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And yet they all come from
the same original cell,
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the fertilized egg.
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How did the first cell
give all these diversity
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of cellular states with the same genome?
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- [Voiceover] It is a question
that Scottish biologist,
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Conrade Waddington, began
to answer in the 1940s.
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He was the first to coin
the term epigenetic.
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Fascinated by the growth of organisms,
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Waddington wondered how
an embryo became a bean
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made up of many varied
cells that all sprang
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from a single cell.
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00:13:44,657 --> 00:13:47,837
- Conrad Waddington drew
a picture of a landscape,
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of a mountain, and at
the top of a mountain
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he placed a cell or a bead,
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and the idea was that at
the top of the mountain,
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the cell could become
many different things
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depending on which path
down the mountain it took.
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00:14:03,498 --> 00:14:05,157
So at the top of the mountain
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is like the multipotent stem cell
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that can become any
different type of cell.
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And as the cell moves down the mountain,
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it becomes more and more committed
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to a particular path depending on
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00:14:17,277 --> 00:14:19,357
which valley it goes in to.
258
00:14:19,357 --> 00:14:21,396
And that will determine its fate.
259
00:14:21,396 --> 00:14:23,813
(calm music)
260
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- [Voiceover] Liver cells, heart cells,
261
00:14:28,556 --> 00:14:30,556
skin cells, brain cells,
262
00:14:32,156 --> 00:14:34,656
the fate and the identity
of our cells are not only
263
00:14:34,656 --> 00:14:36,156
etched in our DNA,
264
00:14:37,736 --> 00:14:39,717
other mechanisms come into play,
265
00:14:39,717 --> 00:14:42,456
so that cells differentiate
and more especially
266
00:14:42,456 --> 00:14:45,981
that they keep the
memory of their identity.
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00:14:45,981 --> 00:14:49,574
- We all know that we began as an egg.
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From that point, each being develops
269
00:14:52,554 --> 00:14:54,754
with this epigenetic function
270
00:14:54,754 --> 00:14:58,554
that enables genetic data to be read.
271
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There's something a
bit magic and all that.
272
00:15:01,714 --> 00:15:03,874
It's wonderful to think that
we're trying to understand
273
00:15:03,874 --> 00:15:07,634
how it works, how I or
how this plant are made
274
00:15:07,634 --> 00:15:10,514
from this genetic data
which has been changing
275
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for two billion years.
276
00:15:15,434 --> 00:15:18,934
And then these epigenetics
can read the system
277
00:15:18,934 --> 00:15:23,101
and make the plant or the human
being that I'm looking at.
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00:15:25,394 --> 00:15:27,093
- The genome were not changed during the
279
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differentiation process,
280
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what will change is the
way that genome is used.
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00:15:30,373 --> 00:15:34,033
And that's epigenetic mechanisms
that will control that,
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00:15:34,033 --> 00:15:36,333
that will determine which
parts of the genome are used
283
00:15:36,333 --> 00:15:39,916
and which parts of the
genome are not used.
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00:15:41,211 --> 00:15:42,931
- [Voiceover] The way
our cells are expressed
285
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is therefore critical to our growth
286
00:15:44,691 --> 00:15:46,524
and that of our cells.
287
00:15:48,231 --> 00:15:50,830
- There had been many ways
to think about epigenetics.
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00:15:50,830 --> 00:15:55,127
One metaphor that that
does work well is music.
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00:15:55,127 --> 00:15:58,460
So, music is written with lines and dots
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and yet the lines and dots are critical
291
00:16:03,147 --> 00:16:04,345
to playing the music.
292
00:16:04,345 --> 00:16:07,262
(calm piano music)
293
00:16:16,925 --> 00:16:19,865
But every time those
lines and dots are played
294
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by a musician or by an orchestra,
295
00:16:21,824 --> 00:16:23,061
they will sound different.
296
00:16:23,061 --> 00:16:26,144
(lively piano music)
297
00:16:28,920 --> 00:16:32,837
So the music written down
could be like the DNA
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00:16:33,740 --> 00:16:37,481
and the expression of
that requires a musician
299
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and an interpretation.
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- [Voiceover] The same
genetic partition can have
301
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several interpretations.
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00:17:02,819 --> 00:17:06,059
Who better to understand this than twins?
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00:17:06,059 --> 00:17:08,259
Born from the same egg, identical twins
304
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share the same DNA.
305
00:17:12,299 --> 00:17:16,479
Are there differences of
interpretation in their genome?
306
00:17:16,479 --> 00:17:17,659
- I love garlic.
307
00:17:17,659 --> 00:17:19,199
- I hate garlic.
308
00:17:19,199 --> 00:17:21,199
- He runs much faster than I do.
309
00:17:21,199 --> 00:17:23,079
- He needs to practice more than I do.
310
00:17:23,079 --> 00:17:24,619
- My French isn't bad.
311
00:17:24,619 --> 00:17:26,379
- I don't speak French.
312
00:17:26,379 --> 00:17:29,046
(comical music)
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00:17:31,419 --> 00:17:33,297
- [Voiceover] Jonathan
Weitzman and his twin, Mathew,
314
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are both researchers.
315
00:17:35,437 --> 00:17:38,218
They share the same DNA
And the same questions
316
00:17:38,218 --> 00:17:39,468
about identity.
317
00:17:40,778 --> 00:17:43,437
- Yeah, maybe we're both
interested in genetics
318
00:17:43,437 --> 00:17:46,478
because we've always been interested in
319
00:17:46,478 --> 00:17:49,278
what's transmitted, what
makes us who we are.
320
00:17:49,278 --> 00:17:51,837
- We're a combination of our genome,
321
00:17:51,837 --> 00:17:54,133
our epigenome, our experiences.
322
00:17:54,133 --> 00:17:57,572
That's what makes me who I am today.
323
00:17:57,572 --> 00:18:00,513
But those experiences and the changes
324
00:18:00,513 --> 00:18:03,789
in our epigenome will
tell me who I am tomorrow.
325
00:18:03,789 --> 00:18:06,456
(comical music)
326
00:18:08,889 --> 00:18:11,589
- The genome is relatively static.
327
00:18:11,589 --> 00:18:15,756
The epigenome is in
comparison relatively dynamic.
328
00:18:16,869 --> 00:18:19,190
Identity, who we are, is
something that changes
329
00:18:19,190 --> 00:18:20,989
all the time throughout life.
330
00:18:20,989 --> 00:18:24,469
And so, the epigenome must in some way
331
00:18:24,469 --> 00:18:28,069
carry memories of that past
and probably contribute
332
00:18:28,069 --> 00:18:29,829
to defining who we are.
333
00:18:29,829 --> 00:18:34,290
So the longer we live, the more
our epigenomes will diverge.
334
00:18:34,290 --> 00:18:36,209
And there are studies that have shown
335
00:18:36,209 --> 00:18:39,249
or begun to show that this is the case.
336
00:18:39,249 --> 00:18:41,666
(calm music)
337
00:18:47,289 --> 00:18:48,929
- [Voiceover] So our
genes are being influenced
338
00:18:48,929 --> 00:18:50,679
throughout our lives.
339
00:18:51,809 --> 00:18:56,209
Our experiences have an
impact on our expression.
340
00:18:56,209 --> 00:18:59,549
How is this expressed in
two people with the same DNA
341
00:18:59,549 --> 00:19:01,299
like identical twins?
342
00:19:02,789 --> 00:19:05,089
That's what Manel Esteller set out to find
343
00:19:05,089 --> 00:19:06,589
here in Barcelona.
344
00:19:08,089 --> 00:19:11,006
(foreign language)
345
00:20:57,445 --> 00:21:00,845
- Studies on twins show that
the DNA conditions what we are
346
00:21:00,845 --> 00:21:02,702
and the disease we develop,
347
00:21:02,702 --> 00:21:04,952
but it's not a closed book.
348
00:21:07,322 --> 00:21:09,402
These studies are
essential in demonstrating
349
00:21:09,402 --> 00:21:12,362
that there is a certain
genetic determinism,
350
00:21:12,362 --> 00:21:13,862
but not 100%.
351
00:21:17,002 --> 00:21:19,202
- [Voiceover] Studies on
identical twins is a way
352
00:21:19,202 --> 00:21:21,422
to better asses the
influence of epigenetics
353
00:21:21,422 --> 00:21:24,255
on the development of individuals.
354
00:21:26,090 --> 00:21:27,430
But do they also play a role
355
00:21:27,430 --> 00:21:30,013
in the appearance of illnesses?
356
00:21:34,770 --> 00:21:37,250
- Studies on identical
twins are also important
357
00:21:37,250 --> 00:21:39,216
in the field of cancer research.
358
00:21:39,216 --> 00:21:41,643
With sisters who have
inherited the genetic mutation
359
00:21:41,643 --> 00:21:45,205
that gives them a higher
risk, let's say 80%, 90%
360
00:21:45,205 --> 00:21:46,985
of contracting breast cancer.
361
00:21:46,985 --> 00:21:48,262
It can happen that one of the sisters
362
00:21:48,262 --> 00:21:52,902
develops cancer at 60 and
the other never or at 90.
363
00:21:52,902 --> 00:21:55,643
How is this possible
that the DNA is the same?
364
00:21:55,643 --> 00:21:59,810
Well, it's because there
are epigenetic differences.
365
00:22:03,363 --> 00:22:05,283
- [Voiceover] So there
are epigenetic differences
366
00:22:05,283 --> 00:22:07,842
between twins, differences
which are sometimes
367
00:22:07,842 --> 00:22:10,983
the sign of anomalies and
could be used as flags
368
00:22:10,983 --> 00:22:14,100
in checking for he appearance
of illnesses like cancer.
369
00:22:14,100 --> 00:22:16,517
(calm music)
370
00:22:23,620 --> 00:22:25,540
By exploring these new territories,
371
00:22:25,540 --> 00:22:29,039
teams like that of Edith
Heard at the Institut Curie
372
00:22:29,039 --> 00:22:31,789
bring renewed hope to this field.
373
00:22:32,679 --> 00:22:36,020
- We know that cancer
is a genetic disease.
374
00:22:36,020 --> 00:22:38,599
We know that changes at
the DNA sequence level
375
00:22:38,599 --> 00:22:41,420
are important in the cancer process.
376
00:22:41,420 --> 00:22:44,060
However, we're starting
to realize more and more
377
00:22:44,060 --> 00:22:46,560
that it's also an epigenetic disease,
378
00:22:46,560 --> 00:22:48,759
that there are changes in gene expression
379
00:22:48,759 --> 00:22:51,040
that don't necessarily involve a change
380
00:22:51,040 --> 00:22:55,259
in DNA sequence that
are actually implicated
381
00:22:55,259 --> 00:22:57,676
in the progression of tumors.
382
00:23:03,680 --> 00:23:06,020
- [Voiceover] Edith Heard's
team has just broken new ground
383
00:23:06,020 --> 00:23:08,853
in understanding these mechanisms.
384
00:23:10,500 --> 00:23:13,060
The researchers focused
particularly on a fascinating
385
00:23:13,060 --> 00:23:16,977
chromosome in female
mammals, the X chromosome.
386
00:23:22,900 --> 00:23:25,181
In human beings and in most mammals,
387
00:23:25,181 --> 00:23:29,400
the sex is determined by
the X and Y chromosomes.
388
00:23:29,400 --> 00:23:33,567
Females inherit two X's
and males, one X and one Y.
389
00:23:35,079 --> 00:23:38,920
But with 100 genes on the
Y against 1,300 on the X,
390
00:23:38,920 --> 00:23:41,087
there's a clear imbalance.
391
00:23:42,021 --> 00:23:44,880
To restore the balance, one
of the two X chromosomes
392
00:23:44,880 --> 00:23:47,420
is inactivated in females
right at the start
393
00:23:47,420 --> 00:23:49,560
of their embryonic development.
394
00:23:49,560 --> 00:23:52,299
In fact, it's an epigenic
mechanism which contributes
395
00:23:52,299 --> 00:23:54,590
to silencing one of the X chromosomes
396
00:23:54,590 --> 00:23:57,431
and above all of maintaining that silence
397
00:23:57,431 --> 00:23:59,488
throughout a female's life.
398
00:23:59,488 --> 00:24:01,126
- X inactivation is essential.
399
00:24:01,126 --> 00:24:03,586
If one of the two X
chromosomes is not shut down
400
00:24:03,586 --> 00:24:05,906
during development of the female,
401
00:24:05,906 --> 00:24:07,905
the embryo dies very early on.
402
00:24:07,905 --> 00:24:09,845
This illustrates how important it is
403
00:24:09,845 --> 00:24:12,024
to get gene dosage right.
404
00:24:12,024 --> 00:24:14,904
If you have an excess
of expression of genes
405
00:24:14,904 --> 00:24:18,163
from the X chromosome,
that leads to lethality.
406
00:24:18,163 --> 00:24:21,246
(lively piano music)
407
00:24:24,023 --> 00:24:25,721
- [Voiceover] Feline or human being,
408
00:24:25,721 --> 00:24:29,888
this process is in fact
inevitable in most female mammals.
409
00:24:37,381 --> 00:24:39,802
To Edith Heard, this vital phenomenon
410
00:24:39,802 --> 00:24:41,902
provides a lot information on how normal
411
00:24:41,902 --> 00:24:44,319
and cancerous cells function.
412
00:24:49,222 --> 00:24:50,661
Throughout our existence,
413
00:24:50,661 --> 00:24:53,602
our cells are renewed by division.
414
00:24:53,602 --> 00:24:56,222
And with each division,
epigenetic mechanisms
415
00:24:56,222 --> 00:24:59,921
keep the memory of the X inactivation.
416
00:24:59,921 --> 00:25:04,088
But what happens when the
cell losses that memory?
417
00:25:09,041 --> 00:25:13,208
That's what researcher Ronan
Chaligne is trying to find out.
418
00:25:15,061 --> 00:25:17,661
In their normal state, in
the nucleus of these cells,
419
00:25:17,661 --> 00:25:21,681
the inactive X is very
inhibited as in this diagram.
420
00:25:21,681 --> 00:25:25,561
But in the breast cancer,
its aspect changes.
421
00:25:25,561 --> 00:25:27,901
- In tumor cells, we've
discovered in recent years
422
00:25:27,901 --> 00:25:29,861
that the inactive X was still present
423
00:25:29,861 --> 00:25:32,982
but there was a change
in its silent state.
424
00:25:32,982 --> 00:25:37,519
This inactive X has a formal
relaxed, less dense structure.
425
00:25:37,519 --> 00:25:39,660
We've noticed that in
cancer cells where the
426
00:25:39,660 --> 00:25:42,580
epigenetic mechanisms are
disturbed and deregulated,
427
00:25:42,580 --> 00:25:45,020
there's a reactivation of
certain inactive X genes
428
00:25:45,020 --> 00:25:47,520
which are normally suppressed.
429
00:25:49,019 --> 00:25:51,658
- [Voiceover] But the fact
that some genes are reactivated
430
00:25:51,658 --> 00:25:53,991
favors the growth of tumors.
431
00:25:55,458 --> 00:25:59,625
This research opens new avenues
of action against cancer.
432
00:26:03,938 --> 00:26:07,378
- Epigenetic changes also
provide hope in cancer
433
00:26:07,378 --> 00:26:09,598
because epigenetic
changes can be reversed.
434
00:26:09,598 --> 00:26:13,558
Unlike DNA sequence mutations
that can't really be reversed
435
00:26:13,558 --> 00:26:17,897
in any easy way, this contrast
with an epigenetic change
436
00:26:17,897 --> 00:26:21,116
which can indeed be
reprogrammed or reversed
437
00:26:21,116 --> 00:26:23,256
with certain molecules.
438
00:26:23,256 --> 00:26:25,556
So currently, there's great hope that
439
00:26:25,556 --> 00:26:27,937
some types of cancer
could actually be treated
440
00:26:27,937 --> 00:26:31,770
by drugs that target the
epigenetic machinery.
441
00:26:34,537 --> 00:26:36,896
- [Voiceover] Molecules
which target these processes,
442
00:26:36,896 --> 00:26:40,861
epi-drugs, are currently
undergoing trials.
443
00:26:40,861 --> 00:26:42,606
But researchers have
discovered that medication
444
00:26:42,606 --> 00:26:44,402
marketed several years ago
445
00:26:44,402 --> 00:26:47,819
unwittingly affect epigenetic mechanisms.
446
00:26:50,782 --> 00:26:53,122
- In fact, one drug that
has been used for many,
447
00:26:53,122 --> 00:26:56,462
many decades turns out to be an epi-drug.
448
00:26:56,462 --> 00:26:59,802
Decitabine, as its
called, is used to treat
449
00:26:59,802 --> 00:27:03,142
myelodysplastic syndrome which is actually
450
00:27:03,142 --> 00:27:07,523
a blood disorder that leads
eventually to leukemia.
451
00:27:07,523 --> 00:27:10,702
And so it was discovered
many, many years ago
452
00:27:10,702 --> 00:27:13,882
as a successful treatment in slowing down
453
00:27:13,882 --> 00:27:15,842
the progression of this disease.
454
00:27:15,842 --> 00:27:18,020
So this is an example of
an epi-drug that is used
455
00:27:18,020 --> 00:27:20,500
in the clinic that is successful.
456
00:27:20,500 --> 00:27:21,940
What's important to know though
457
00:27:21,940 --> 00:27:24,780
is we don't actually
understand the targets
458
00:27:24,780 --> 00:27:26,140
of these epi-drugs.
459
00:27:26,140 --> 00:27:28,640
We know that some of them
can work in the clinic
460
00:27:28,640 --> 00:27:31,378
but the challenge now is to
understand how they do it.
461
00:27:31,378 --> 00:27:34,738
(lively piano music)
462
00:27:34,738 --> 00:27:36,618
- [Voiceover] Epi-drugs
present a promising lead
463
00:27:36,618 --> 00:27:38,951
in the fight against cancer.
464
00:27:41,258 --> 00:27:43,038
The role of epigenetics in the development
465
00:27:43,038 --> 00:27:45,478
of individuals and of certain diseases
466
00:27:45,478 --> 00:27:47,978
is gradually becoming clearer.
467
00:27:51,838 --> 00:27:53,858
But in the same way that genes are passed
468
00:27:53,858 --> 00:27:55,678
from one generation to another,
469
00:27:55,678 --> 00:27:57,518
could these mechanisms that influence
470
00:27:57,518 --> 00:28:01,018
the gene expression also be transmissible?
471
00:28:15,198 --> 00:28:17,258
- At what type of
information is transmitted
472
00:28:17,258 --> 00:28:20,418
to the next generation is
still a very open question.
473
00:28:20,418 --> 00:28:22,778
We know that characteristics
have been transmitted
474
00:28:22,778 --> 00:28:26,266
but I look like my father and my mother.
475
00:28:26,266 --> 00:28:29,266
My son and my daughter look like me.
476
00:28:30,164 --> 00:28:32,364
So, where does this come from?
477
00:28:32,364 --> 00:28:34,447
We focus a lot on the DNA
478
00:28:35,843 --> 00:28:37,783
mainly because we could.
479
00:28:37,783 --> 00:28:39,282
It's easy to measure.
480
00:28:39,282 --> 00:28:41,563
It's easy to find the sequence.
481
00:28:41,563 --> 00:28:43,140
Now, we're interested more and more
482
00:28:43,140 --> 00:28:46,170
in what's transmitted with the DNA
483
00:28:46,170 --> 00:28:48,448
or around the DNA or above the DNA.
484
00:28:48,448 --> 00:28:50,865
(calm music)
485
00:28:52,528 --> 00:28:53,907
- [Voiceover] How can
we get a better insight
486
00:28:53,907 --> 00:28:55,824
into this transmission?
487
00:28:57,427 --> 00:29:01,427
Currently the best clues
are supplied by plants.
488
00:29:04,287 --> 00:29:07,084
Geneticist Vincent Colot
has carried out research
489
00:29:07,084 --> 00:29:09,844
on a little plant from the
same family as mustard,
490
00:29:09,844 --> 00:29:13,662
a plant called Arabidopsis
or mouse-ear cress.
491
00:29:13,662 --> 00:29:16,079
(calm music)
492
00:29:19,721 --> 00:29:22,922
- Arabidopsis is a plant
which is of great interest
493
00:29:22,922 --> 00:29:26,988
to geneticists because
it is very prolific.
494
00:29:26,988 --> 00:29:28,389
It has a very short development time,
495
00:29:28,389 --> 00:29:30,369
in other words, it can
go from seed to seed
496
00:29:30,369 --> 00:29:33,308
in less than two months
and the cherry on a cake,
497
00:29:33,308 --> 00:29:36,391
we know it has a very compact genome.
498
00:29:42,241 --> 00:29:44,602
- [Voiceover] Can Arabidopsis
pass on to subsequent
499
00:29:44,602 --> 00:29:48,701
generations visible changes
such as longer or shorter roots
500
00:29:48,701 --> 00:29:51,076
or early or later flowering without this
501
00:29:51,076 --> 00:29:53,159
being written in the DNA?
502
00:29:54,199 --> 00:29:57,919
To find out, researchers
induced epigenetic modifications
503
00:29:57,919 --> 00:29:59,919
in an Arabidopsis plant.
504
00:30:03,799 --> 00:30:07,139
They then crossed this
plant with a wild plant.
505
00:30:07,139 --> 00:30:09,419
And after successive crossbreeding,
506
00:30:09,419 --> 00:30:13,586
they obtained a family of
plants over several generations.
507
00:30:17,118 --> 00:30:20,758
The first major discovery,
these epigenetic modifications
508
00:30:20,758 --> 00:30:22,738
are transmitted and remained stable
509
00:30:22,738 --> 00:30:25,405
through at least 16 generations.
510
00:30:28,838 --> 00:30:31,378
The second observation,
these modifications
511
00:30:31,378 --> 00:30:34,578
are associated with visible
changes such us root length
512
00:30:34,578 --> 00:30:36,578
or the flowering period.
513
00:30:37,778 --> 00:30:39,658
So, for the first time,
514
00:30:39,658 --> 00:30:41,638
scientists are able to show evidence
515
00:30:41,638 --> 00:30:44,178
that characteristics can
be transmitted over a large
516
00:30:44,178 --> 00:30:46,657
number of generations without any change
517
00:30:46,657 --> 00:30:48,490
in the DNA sequencing.
518
00:30:51,674 --> 00:30:54,939
- What we also found was that
this epigenetic variation
519
00:30:54,939 --> 00:30:56,439
passed on through the generations
520
00:30:56,439 --> 00:30:59,119
has a lower stability
than that of the states
521
00:30:59,119 --> 00:31:00,619
of DNA sequencing.
522
00:31:02,819 --> 00:31:07,339
The sequence of the DNA is 80
GC written in a particular way
523
00:31:07,339 --> 00:31:09,679
and transmitted with extreme fidelity
524
00:31:09,679 --> 00:31:12,580
unlike the epigenetic state
which evidently appeared
525
00:31:12,580 --> 00:31:14,080
to be less stable.
526
00:31:14,939 --> 00:31:17,339
In other words, this
transmission we're measuring
527
00:31:17,339 --> 00:31:19,939
will last for certain
number of generations,
528
00:31:19,939 --> 00:31:22,139
tens or even hundreds of generations,
529
00:31:22,139 --> 00:31:25,097
but certainly not millions of generations.
530
00:31:25,097 --> 00:31:27,514
(calm music)
531
00:31:33,417 --> 00:31:35,077
- [Voiceover] Thanks to this experiment,
532
00:31:35,077 --> 00:31:37,057
scientists have evidence
of the transmission
533
00:31:37,057 --> 00:31:40,317
of epigenetic marks which
modify certain aspects
534
00:31:40,317 --> 00:31:41,400
of the plant.
535
00:31:43,057 --> 00:31:45,417
In this case, the
modifications have been induced
536
00:31:45,417 --> 00:31:49,584
in a first generation of
plants in the laboratory.
537
00:31:51,117 --> 00:31:53,367
But what happens in nature?
538
00:31:57,177 --> 00:31:59,896
Can these changes be
induced by the environment
539
00:31:59,896 --> 00:32:02,563
in case of drought, for example?
540
00:32:03,780 --> 00:32:07,404
- We're facing an unknown,
the part environment plays
541
00:32:07,404 --> 00:32:09,485
over the way genes function.
542
00:32:09,485 --> 00:32:11,704
But how far does that environment dictate
543
00:32:11,704 --> 00:32:14,724
heritable changes over generations?
544
00:32:14,724 --> 00:32:15,964
That's an open question.
545
00:32:15,964 --> 00:32:18,381
Does environment play a part?
546
00:32:23,904 --> 00:32:25,365
- [Voiceover] To answer this question,
547
00:32:25,365 --> 00:32:28,048
Vincent Colot and his
researchers at INRA have launched
548
00:32:28,048 --> 00:32:29,465
a new experiment.
549
00:32:30,368 --> 00:32:32,888
They have installed hundreds
of genetically identical plants
550
00:32:32,888 --> 00:32:34,826
on the conveyor belts of this system
551
00:32:34,826 --> 00:32:37,264
that's unique in the
world, the Phenoscope.
552
00:32:37,264 --> 00:32:39,764
(jazzy music)
553
00:32:46,044 --> 00:32:49,123
The mechanical rotation
system exposes the Arabidopsis
554
00:32:49,123 --> 00:32:52,144
plants to the same light and
enables only the watering
555
00:32:52,144 --> 00:32:55,061
to be varied to measure its impact.
556
00:32:59,932 --> 00:33:02,232
- The question we're
trying to answer now is
557
00:33:02,232 --> 00:33:05,412
what are the conditions
that lead to the appearance
558
00:33:05,412 --> 00:33:07,495
of epigenetic variations.
559
00:33:09,013 --> 00:33:11,433
Is the environment itself
capable of inducing
560
00:33:11,433 --> 00:33:13,153
this type of change?
561
00:33:13,153 --> 00:33:16,673
And if so, are the changes
we observe as stable as those
562
00:33:16,673 --> 00:33:20,513
we've managed to establish
experimentally in the laboratory
563
00:33:20,513 --> 00:33:24,033
over how many generations
and with what range?
564
00:33:24,033 --> 00:33:25,953
That's more or less the range of questions
565
00:33:25,953 --> 00:33:28,292
we can tackle, thanks
to this totally unique
566
00:33:28,292 --> 00:33:30,870
experimental system, the Phenoscope.
567
00:33:30,870 --> 00:33:33,287
(calm music)
568
00:33:39,851 --> 00:33:41,350
- [Voiceover] The result of this research
569
00:33:41,350 --> 00:33:43,330
are eagerly awaited.
570
00:33:43,330 --> 00:33:45,623
They will enable us to see
whether environmental factors
571
00:33:45,623 --> 00:33:48,083
such as drought can
influence the plant genome
572
00:33:48,083 --> 00:33:50,166
over several generations.
573
00:33:59,184 --> 00:34:01,723
What do we know of other species?
574
00:34:01,723 --> 00:34:03,963
What can we say about
the impact of environment
575
00:34:03,963 --> 00:34:06,144
on our own genome?
576
00:34:06,144 --> 00:34:09,108
- It's an ongoing search and debate
577
00:34:09,108 --> 00:34:11,292
to understand exactly what is transmitted
578
00:34:11,292 --> 00:34:14,053
to the next generation,
how much other information
579
00:34:14,053 --> 00:34:15,693
is transmitted.
580
00:34:15,693 --> 00:34:18,653
Do we transmit information
about the environment
581
00:34:18,653 --> 00:34:20,553
in which we live?
582
00:34:20,553 --> 00:34:24,953
Some people think it may be
quite subtle, fine tuning.
583
00:34:24,953 --> 00:34:27,471
Some people think that it
may have a very big impact.
584
00:34:27,471 --> 00:34:29,888
(calm music)
585
00:34:47,038 --> 00:34:48,418
- [Voiceover] Thousands of kilometers away
586
00:34:48,418 --> 00:34:51,218
in the American Northwest,
a researcher is convinced
587
00:34:51,218 --> 00:34:52,819
that environment plays a major role
588
00:34:52,819 --> 00:34:56,125
in our organism and that
it leaves lasting traces
589
00:34:56,125 --> 00:34:59,458
transmissible via epigenetic mechanisms.
590
00:35:01,844 --> 00:35:04,125
A specialist in reproductive biology,
591
00:35:04,125 --> 00:35:08,464
Michael Skinner, came to
epigenetics rather by accident.
592
00:35:08,464 --> 00:35:11,385
An error manipulation enabled
him to study the effects
593
00:35:11,385 --> 00:35:15,525
of pesticides on several
generations of rats.
594
00:35:15,525 --> 00:35:19,385
- Most scientific observations are not
595
00:35:19,385 --> 00:35:22,725
necessarily plant and so
this is what you would call
596
00:35:22,725 --> 00:35:24,684
a serendipitous observation.
597
00:35:24,684 --> 00:35:28,767
So we were studying the
effects of this fungicide
598
00:35:30,064 --> 00:35:32,064
on the gestating female
599
00:35:33,244 --> 00:35:35,105
and we wanted to see what would happen
600
00:35:35,105 --> 00:35:37,624
if a fetus was exposed to its health
601
00:35:37,624 --> 00:35:42,005
when it was born and grew
up to become an adult.
602
00:35:42,005 --> 00:35:43,704
- [Voiceover] The American
researchers' study
603
00:35:43,704 --> 00:35:46,225
focuses on the effects of pesticides.
604
00:35:46,225 --> 00:35:47,993
They were looking to gauge their impact
605
00:35:47,993 --> 00:35:50,493
on the fertility of male rats.
606
00:35:52,113 --> 00:35:56,280
They had therefore injected
pesticide into pregnant females.
607
00:35:57,413 --> 00:36:01,032
When the babies were born,
there were no anomalies.
608
00:36:01,032 --> 00:36:03,528
But as adults, the male sperm count
609
00:36:03,528 --> 00:36:05,945
signaled a drop in fertility.
610
00:36:08,415 --> 00:36:11,015
These males reproduced for the first time.
611
00:36:11,015 --> 00:36:15,182
Their offspring in turn
presented defective sperm.
612
00:36:16,515 --> 00:36:18,795
The crossbreeding
continued through to their
613
00:36:18,795 --> 00:36:20,995
great-grandchildren.
614
00:36:20,995 --> 00:36:23,035
Then came a surprise.
615
00:36:23,035 --> 00:36:26,075
The same anomalies were
observed in the male descendants
616
00:36:26,075 --> 00:36:28,655
though there was no more
direct exposure to pesticides
617
00:36:28,655 --> 00:36:32,822
neither via injection nor
via the maternal uterus.
618
00:36:33,796 --> 00:36:35,796
Moreover, with each generation,
619
00:36:35,796 --> 00:36:38,055
epigenetic modifications were discovered
620
00:36:38,055 --> 00:36:41,055
and correlated with sperm anomalies.
621
00:36:41,956 --> 00:36:46,555
- 90% of the males had this
reproductive abnormality
622
00:36:46,555 --> 00:36:49,575
that was carried for four generations.
623
00:36:49,575 --> 00:36:51,190
And so, that showed us that we had
624
00:36:51,190 --> 00:36:54,809
a phenomena that was not
following classic genetics,
625
00:36:54,809 --> 00:36:56,969
it was definitely different.
626
00:36:56,969 --> 00:36:58,709
And so we follow that up to show
627
00:36:58,709 --> 00:37:00,436
that there was this epigenetic
628
00:37:00,436 --> 00:37:02,936
transgenerational inheritance.
629
00:37:04,116 --> 00:37:06,496
- [Voiceover] Have these
results been confirmed?
630
00:37:06,496 --> 00:37:07,415
Not really.
631
00:37:07,415 --> 00:37:11,582
But no one has reproduced a
study in the same conditions.
632
00:37:14,195 --> 00:37:16,596
Michael Skinner claims to
have shown that pesticides
633
00:37:16,596 --> 00:37:18,976
can cause non-genetic anomalies
634
00:37:18,976 --> 00:37:21,809
that are transmissible in rodents.
635
00:37:24,716 --> 00:37:27,154
Some decry the work as too partial
636
00:37:27,154 --> 00:37:28,834
with hasty conclusions that undermine
637
00:37:28,834 --> 00:37:32,501
the concepts of heredity
and trigger debate.
638
00:37:33,534 --> 00:37:35,934
- You're not doing
something controversial,
639
00:37:35,934 --> 00:37:39,692
you're not doing something
really important.
640
00:37:39,692 --> 00:37:42,030
You know, the subtle of
changes are not important,
641
00:37:42,030 --> 00:37:43,591
it's a matter of you're not gonna make
642
00:37:43,591 --> 00:37:45,448
the big steps in science.
643
00:37:45,448 --> 00:37:49,308
So if all of the scientists
started thinking that way,
644
00:37:49,308 --> 00:37:50,828
then there would be challenges
645
00:37:50,828 --> 00:37:54,127
to all of our dogmas
much, much more rigorously
646
00:37:54,127 --> 00:37:55,666
than there is today.
647
00:37:55,666 --> 00:37:58,987
But instead, we have this
tendency to accept the dogma
648
00:37:58,987 --> 00:38:01,766
and work within it without challenging it.
649
00:38:01,766 --> 00:38:03,727
So that's not the best way science
650
00:38:03,727 --> 00:38:05,894
should be done in my mind.
651
00:38:09,346 --> 00:38:10,326
- [Voiceover] Here and there,
652
00:38:10,326 --> 00:38:11,926
experiments similar to
that of Micheal Skinner
653
00:38:11,926 --> 00:38:13,176
were conducted.
654
00:38:14,087 --> 00:38:16,463
Here in Zurich, Isabelle Mansuy's team
655
00:38:16,463 --> 00:38:18,981
was also seeking proof
that epigenetic heritage
656
00:38:18,981 --> 00:38:21,461
was linked to the environment.
657
00:38:21,461 --> 00:38:23,679
But this time the subject was stress.
658
00:38:23,679 --> 00:38:26,346
Is it biologicaly transmissible?
659
00:38:28,284 --> 00:38:30,897
- We use the mouse as an animal model
660
00:38:30,897 --> 00:38:34,815
to test the theory that
exposure to traumatic stress
661
00:38:34,815 --> 00:38:37,055
during childhood can alter
662
00:38:37,055 --> 00:38:39,935
the epigenetic mechanisms permanently
663
00:38:39,935 --> 00:38:42,102
and modify adult behavior.
664
00:38:48,925 --> 00:38:51,194
- [Voiceover] To create
trauma in suckling mice,
665
00:38:51,194 --> 00:38:53,035
the young were separated
from their mothers
666
00:38:53,035 --> 00:38:55,368
unexpectedly and repeatedly.
667
00:39:02,295 --> 00:39:04,374
- What we were able to show is that
668
00:39:04,374 --> 00:39:07,235
exposure to periods of chronic stress
669
00:39:07,235 --> 00:39:09,315
altered the mouse's behavior.
670
00:39:09,315 --> 00:39:11,732
And also in parallel
altered a certain number
671
00:39:11,732 --> 00:39:15,312
of epigenetic mechanisms in
the brain and in offspring
672
00:39:15,312 --> 00:39:17,813
and that these epigenetic modifications
673
00:39:17,813 --> 00:39:20,813
were passed through the generations.
674
00:39:21,913 --> 00:39:23,869
- [Voiceover] The baby mice
that grew up in this conditions
675
00:39:23,869 --> 00:39:26,430
were depressed as adults.
676
00:39:26,430 --> 00:39:30,597
They evaluated danger less
well and took more risks,
677
00:39:33,410 --> 00:39:35,910
disorders that they pass
on to their descendants
678
00:39:35,910 --> 00:39:38,910
as far as their great grandchildren.
679
00:39:40,149 --> 00:39:43,009
- An important lesson we
can draw from these results
680
00:39:43,009 --> 00:39:46,289
is that not everything
resides in the genes.
681
00:39:46,289 --> 00:39:48,950
But the environmental factors
to which we are exposed
682
00:39:48,950 --> 00:39:52,270
in particular trauma during
childhood are very important
683
00:39:52,270 --> 00:39:54,770
and can determine our behavior in our life
684
00:39:54,770 --> 00:39:57,020
across several generations.
685
00:40:04,993 --> 00:40:07,347
What excites me about
the field of epigenetics
686
00:40:07,347 --> 00:40:08,707
is the consequences,
687
00:40:08,707 --> 00:40:10,727
the applications for human beings,
688
00:40:10,727 --> 00:40:12,608
especially in psychiatry
689
00:40:12,608 --> 00:40:14,628
because there are many
psychiatric illnesses
690
00:40:14,628 --> 00:40:16,228
like depressions, schizophrenia,
691
00:40:16,228 --> 00:40:18,968
personality disorders that aren't known.
692
00:40:18,968 --> 00:40:21,427
We don't know the causes,
we don't know the mechanisms
693
00:40:21,427 --> 00:40:23,767
and we think that our
research into epigenetics
694
00:40:23,767 --> 00:40:27,934
could lead to a better
understanding of these diseases.
695
00:40:31,208 --> 00:40:32,587
- [Voiceover] It is much too early to say
696
00:40:32,587 --> 00:40:36,670
whether we can pass on
stress as the mouse could.
697
00:40:46,006 --> 00:40:47,966
According to the work of Isabelle Mansuy
698
00:40:47,966 --> 00:40:50,726
and Michael Skinner,
genomes are like sponges,
699
00:40:50,726 --> 00:40:53,360
absorbing the slightest
effects of the environment.
700
00:40:53,360 --> 00:40:56,443
(lively piano music)
701
00:40:58,519 --> 00:41:00,659
Effects that leave
traces that are passed on
702
00:41:00,659 --> 00:41:02,659
for several generations.
703
00:41:04,294 --> 00:41:07,295
(dramatic piano music)
704
00:41:07,295 --> 00:41:09,055
These conclusion are the subject of debate
705
00:41:09,055 --> 00:41:11,415
within the scientific community.
706
00:41:11,415 --> 00:41:12,955
- In fact, if you think about it,
707
00:41:12,955 --> 00:41:15,632
if we were that susceptible
to environmentally induced
708
00:41:15,632 --> 00:41:18,391
epigenetic changes, we'd be a mess.
709
00:41:18,391 --> 00:41:22,410
All cell types will change
identity, probably tumors,
710
00:41:22,410 --> 00:41:24,288
and actually we'll
probably not even be here.
711
00:41:24,288 --> 00:41:26,038
We wouldn't be alive.
712
00:41:38,989 --> 00:41:41,809
- [Voiceover] How far are we
affected by our environment?
713
00:41:41,809 --> 00:41:45,059
And what do we pass on to our children?
714
00:41:46,668 --> 00:41:49,088
In reality, the influence of epigenetics
715
00:41:49,088 --> 00:41:53,255
comes up against limits that
have just been discovered.
716
00:41:56,768 --> 00:42:00,408
In sperm and ova, then at
the moment of fertilization,
717
00:42:00,408 --> 00:42:03,668
a large portion of the
epigenetic marks are erased
718
00:42:03,668 --> 00:42:07,751
enabling a kind of reboot
for the new generation.
719
00:42:13,048 --> 00:42:15,568
But this spring cleaning is incomplete,
720
00:42:15,568 --> 00:42:17,818
some marks remain in place.
721
00:42:19,089 --> 00:42:20,672
Which ones and why?
722
00:42:21,648 --> 00:42:24,087
That's the mystery that
Wolf Reik and his team
723
00:42:24,087 --> 00:42:26,920
are working to solve in Cambridge.
724
00:42:28,547 --> 00:42:32,505
- On aspect of the
transgenerational epigenetics
725
00:42:32,505 --> 00:42:35,088
is probably incomplete erasure.
726
00:42:36,145 --> 00:42:39,505
We would like to
understand what's going on.
727
00:42:39,505 --> 00:42:43,672
A choice between what's
erased and what is not erased,
728
00:42:44,805 --> 00:42:48,466
and also if that choice could be changed.
729
00:42:48,466 --> 00:42:52,077
So for example, if the
environmental conditions
730
00:42:52,077 --> 00:42:55,476
are different, if the
food supply is different,
731
00:42:55,476 --> 00:42:58,217
if the nutrition is different,
732
00:42:58,217 --> 00:43:02,297
is there a mechanism by
which it could switch
733
00:43:02,297 --> 00:43:05,176
this choice between erasing information
734
00:43:05,176 --> 00:43:08,076
and giving it to future generations.
735
00:43:08,076 --> 00:43:11,159
It is a very, very exciting question.
736
00:43:12,517 --> 00:43:13,757
- [Voiceover] This selecting erasing
737
00:43:13,757 --> 00:43:16,557
can be seen under the microscope.
738
00:43:16,557 --> 00:43:19,390
These are very early embryo cells.
739
00:43:20,456 --> 00:43:22,037
The nuclei are blue
740
00:43:22,037 --> 00:43:25,017
with practically no epigenetic marks.
741
00:43:25,017 --> 00:43:27,357
And purple are the few marks retained
742
00:43:27,357 --> 00:43:30,440
that were transmitted by the parents.
743
00:43:31,497 --> 00:43:34,316
But take a look a few days later,
744
00:43:34,316 --> 00:43:36,356
the cells, now more developed
745
00:43:36,356 --> 00:43:38,716
at a more advanced embryonic stage,
746
00:43:38,716 --> 00:43:40,717
are already harboring a constellation
747
00:43:40,717 --> 00:43:44,097
of new epigenetic marks
linked to their growth.
748
00:43:44,097 --> 00:43:47,052
- Probably for the last 10 years or so,
749
00:43:47,052 --> 00:43:51,192
we have been very actively
studying this erasure process
750
00:43:51,192 --> 00:43:53,492
because it really fascinated us.
751
00:43:53,492 --> 00:43:56,192
I think there are many unexplored areas,
752
00:43:56,192 --> 00:43:57,692
it's probably true
753
00:43:59,451 --> 00:44:00,951
that the epigenome
754
00:44:02,170 --> 00:44:06,337
is influenced by nutrition,
by the food that we have,
755
00:44:08,403 --> 00:44:11,890
where we grow up, and
environment and things like that,
756
00:44:11,890 --> 00:44:16,030
and also potentially, what
happened to our parents,
757
00:44:16,030 --> 00:44:20,197
in terms of the environment,
the food and things like that.
758
00:44:26,568 --> 00:44:28,608
- [Voiceover] A few phases
from Wolf Reik's laboratory,
759
00:44:28,608 --> 00:44:30,888
still in Cambridge, a team of researchers
760
00:44:30,888 --> 00:44:33,468
wanted to clarify another issue.
761
00:44:33,468 --> 00:44:36,328
Is food capable of marking our DNA?
762
00:44:36,328 --> 00:44:40,411
And if so, do we pass this
on to our descendants?
763
00:44:51,408 --> 00:44:53,988
Anne Ferguson-Smith is
examining the impact
764
00:44:53,988 --> 00:44:56,308
of food deprivation on a pregnant mouse
765
00:44:56,308 --> 00:44:59,891
on her young and on
subsequent generations.
766
00:45:02,128 --> 00:45:06,148
- When a mother is caloricly
restricted during pregnancy,
767
00:45:06,148 --> 00:45:08,565
she's gonna have quite profound
effects on her offspring.
768
00:45:08,565 --> 00:45:10,506
And this particular mouse model
769
00:45:10,506 --> 00:45:12,845
is a 50% caloric restriction.
770
00:45:12,845 --> 00:45:14,781
That's a very severe undernourishment.
771
00:45:14,781 --> 00:45:18,822
And the mice are born small,
the babies are very small
772
00:45:18,822 --> 00:45:21,989
and they go on in adulthood to get fat
773
00:45:23,319 --> 00:45:24,402
and diabetic.
774
00:45:25,298 --> 00:45:29,339
They don't metabolize glucose
properly or insulin properly
775
00:45:29,339 --> 00:45:32,238
and they have, disease is very similar
776
00:45:32,238 --> 00:45:35,434
to what we see in our population today
777
00:45:35,434 --> 00:45:39,177
with this increase incidence of adiposity,
778
00:45:39,177 --> 00:45:41,010
obesity, and diabetes.
779
00:45:41,877 --> 00:45:44,935
In this model, if you
continue to undernourish
780
00:45:44,935 --> 00:45:48,335
the embryo after birth,
the symptoms don't arise
781
00:45:48,335 --> 00:45:51,835
and actually the animals are very healthy.
782
00:45:53,533 --> 00:45:55,393
- [Voiceover] It's as
if the baby mice exposed
783
00:45:55,393 --> 00:45:57,093
to food deprivation in the womb
784
00:45:57,093 --> 00:46:00,593
were programmed to adapt to this shortage.
785
00:46:02,985 --> 00:46:04,693
And when they grow up in an environment
786
00:46:04,693 --> 00:46:06,448
where food is abundant,
787
00:46:06,448 --> 00:46:08,327
they are no longer well adapted
788
00:46:08,327 --> 00:46:11,077
and develop diabetes and obesity.
789
00:46:15,588 --> 00:46:17,848
The next generation, the grandchildren,
790
00:46:17,848 --> 00:46:19,765
show the same symptoms.
791
00:46:22,448 --> 00:46:26,615
How many generations can be
affected by these illnesses?
792
00:46:27,807 --> 00:46:30,724
The research on mice is continuing.
793
00:46:35,508 --> 00:46:37,867
But how can we find out
whether food is capable
794
00:46:37,867 --> 00:46:41,034
of having such an influence in humans?
795
00:46:42,267 --> 00:46:44,086
- So obviously, one can't do experiments
796
00:46:44,086 --> 00:46:46,406
on human populations like this.
797
00:46:46,406 --> 00:46:48,506
But we do know that in history
798
00:46:48,506 --> 00:46:52,726
there are situations where
there have been similar
799
00:46:52,726 --> 00:46:56,393
environmental compromises
to pregnant women.
800
00:46:57,346 --> 00:46:59,806
In particular, the Dutch Hunger Winter
801
00:46:59,806 --> 00:47:01,806
of the Second World War.
802
00:47:02,846 --> 00:47:05,046
- [Voiceover] During the winter of 1944,
803
00:47:05,046 --> 00:47:08,506
part of the Netherlands
suffered greatly from famine.
804
00:47:08,506 --> 00:47:11,006
In order to punish them for
their support of the allies,
805
00:47:11,006 --> 00:47:15,344
the Nazi occupants blocked
all food deliveries.
806
00:47:15,344 --> 00:47:17,364
The survivors and the descendants
807
00:47:17,364 --> 00:47:20,945
are of particular interest to
researchers in epigenetics.
808
00:47:20,945 --> 00:47:23,144
- So these are very moving pictures
809
00:47:23,144 --> 00:47:24,822
and in fact, here,
there are pregnant women
810
00:47:24,822 --> 00:47:26,662
and you can really see the challenges
811
00:47:26,662 --> 00:47:28,202
that they must be facing
812
00:47:28,202 --> 00:47:30,682
in this time of deprivation.
813
00:47:30,682 --> 00:47:32,402
The children of these pregnant women
814
00:47:32,402 --> 00:47:34,783
have been analyzed and had been shown
815
00:47:34,783 --> 00:47:37,601
to have increased incidence
of adult-onset diseases
816
00:47:37,601 --> 00:47:39,768
such as diabetes, obesity,
817
00:47:43,039 --> 00:47:44,560
neurological disorders
818
00:47:44,560 --> 00:47:47,159
such as anxiety and
depression and schizophrenia.
819
00:47:47,159 --> 00:47:50,259
And also an increase incidence
of cardio-vascular disease.
820
00:47:50,259 --> 00:47:51,759
But what has been discovered is that
821
00:47:51,759 --> 00:47:54,519
the offspring of the sons of these women
822
00:47:54,519 --> 00:47:56,959
are heavier as adults.
823
00:47:56,959 --> 00:47:59,039
So this does tells us that the environment
824
00:47:59,039 --> 00:48:00,659
is having some kind of effect
825
00:48:00,659 --> 00:48:03,174
over at least a couple of generations.
826
00:48:03,174 --> 00:48:05,591
(calm music)
827
00:48:08,095 --> 00:48:09,574
- [Voiceover] Research
devoted to the impact
828
00:48:09,574 --> 00:48:12,693
of the environment on the
genome has only just begun
829
00:48:12,693 --> 00:48:17,033
and there are number of
mysteries to be cleared up.
830
00:48:17,033 --> 00:48:18,572
- So genetics is wonderful.
831
00:48:18,572 --> 00:48:23,052
It's the most important
mechanism for transmitting
832
00:48:23,052 --> 00:48:25,552
healthy and unhealthy outcomes
833
00:48:26,472 --> 00:48:29,133
from one generation to the other.
834
00:48:29,133 --> 00:48:31,213
But what is emerging now is that
835
00:48:31,213 --> 00:48:33,732
there's something else
on top of the genetics
836
00:48:33,732 --> 00:48:37,312
that can have an impact
on health and well-being
837
00:48:37,312 --> 00:48:39,253
from one generation to the next.
838
00:48:39,253 --> 00:48:41,833
And to me it's an extremely
exciting prospect,
839
00:48:41,833 --> 00:48:43,813
trying to understand what that mechanism
840
00:48:43,813 --> 00:48:46,732
might be, that non-genetic mechanism
841
00:48:46,732 --> 00:48:50,193
for conferring this
intergenerational effect.
842
00:48:50,193 --> 00:48:53,860
- What excites me about
epigenetics is that,
843
00:48:54,773 --> 00:48:58,940
it gives us lots of waste
to express a static genome
844
00:49:00,451 --> 00:49:03,751
and it gives us a way
to look at the traces
845
00:49:03,751 --> 00:49:07,291
of environmental impacts
and the traces of our own
846
00:49:07,291 --> 00:49:11,511
personal histories on
the way genomes behave.
847
00:49:11,511 --> 00:49:14,091
And I think what I like particularly
848
00:49:14,091 --> 00:49:15,911
is that it's reversible.
849
00:49:15,911 --> 00:49:18,171
It's sort of of optimistic
850
00:49:18,171 --> 00:49:20,588
that nothing is set in stone.
851
00:49:21,670 --> 00:49:24,810
- Effectively, this widens
the field of genetics.
852
00:49:24,810 --> 00:49:26,210
We're not dealing with something
853
00:49:26,210 --> 00:49:28,230
that is passed on unchangingly.
854
00:49:28,230 --> 00:49:29,750
But there's a wealth of possibilities
855
00:49:29,750 --> 00:49:32,127
between an almost evanescent transmission
856
00:49:32,127 --> 00:49:34,802
to something that is
virtually engraved in marble.
857
00:49:34,802 --> 00:49:37,300
And epigenetics occupies a large part
858
00:49:37,300 --> 00:49:39,883
of what isn't written in stone.
859
00:49:42,099 --> 00:49:44,699
- [Voiceover] Epigenetics
is now in full swing.
860
00:49:44,699 --> 00:49:47,800
Research is growing all the time.
861
00:49:47,800 --> 00:49:49,520
But it will take a few more years
862
00:49:49,520 --> 00:49:51,170
and a good many studies
863
00:49:51,170 --> 00:49:55,321
to fully grasp the subtleties
of life's lush musical score.
864
00:49:55,321 --> 00:49:58,404
(lively piano music)
64709
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