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Now we're in the office that's attached to
my lab.

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And we're going to take a few minutes just
to talk about the research that's going

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on, and connect it, if possible, to the

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subjects that we learned about during the
course.

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Now if you remember, we talked about how a
seedling grows in the dark and the light.

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That a seedling that's grown in the dark,
it has a long hypocotyl, and

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its leaves are closed and its elongated.
Whereas, one that

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grows in the light is short, and its, and
its, and

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its called a leadance, its first leaves
are open and expanded.

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We also mentioned how this type of, of a
seedling, one that's grown in

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the light, will continue on into sexual

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development, seeds, and flowering, while
this one arrests.

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Well, the question that interested me 20
years ago, when

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I started my post doc was, how does, how
do plants

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use light as a developmental signal?

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because we know that it's enough to, you
know,

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give this plant a few seconds of light,
and then we will get photomorphogenesis.

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Okay.

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So work that had been done in other labs
showed that

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it was actually sunlight coming through

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the photoreceptors, such as, from
phytochrome

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or from cryptochrome, so either the red
light or the blue

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light, which then converge to allow plants
to go through photomorphogenesis.

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And I want to know is, how are plants
differentiating between dark and light?

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And the way we did this was genetic.

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We found mutant plants that when they were
in the dark, they were still short

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and that open cotyledons, even though,
that's a moon there.

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Okay, see my, my, my drawing abilities
isn't the best in the world.

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Even though, they were in the dark.

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These seedlings in the dark look just like
normal seedlings in the light, okay?

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So the question was what was wrong with
these seedlings?

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What we discovered was that was a group of
eight proteins, that I'll call

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[NOISE]

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the CSN, the compromising signalasome is a
group of eight proteins.

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And what do we discover?

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That the role of the CSN is to repress.
This is a symbol meaning repress.

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It represses photomorphogenesis in the
light, in the dark.

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Excuse me.

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So under normal dark conditions, the COP9
signalosome inhibits this.

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And we get this type of growing.

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What happens is that the light signals
coming

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from phytochrome and cryptochrome impinge
on the COP9 signalosome.

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But what's their function?

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Their function is negative.

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They inhibit the inhibitor, so if the
light

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signals inhibit the COP9 signalosome that
means as your

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light conditions we get further more
photogenesis, and here

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is how we could see how the genetic works.

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Because what's happens

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if I have the mutant in the COP9
signalosome, that a mutant

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in one of these eight sub units so that it
doesn't work,

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then we never have the repression, doesn't
matter if it's in the

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light or the dark, there's no repression
so we'll always get photomorphogensis.

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Now here comes the, what I think is the
most interesting part of all.

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So, on the one hand we identified a
negative

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regulator of photomorphogenesis that's
downstream of the,

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of the photoreceptors from phytochrome and
cryptochrome.

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This is something that's very specific for
plants.

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I also talked about this in one of the
lectures.

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Opening our leaves in the light.

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Opening the leaves in the light is a plant
specific process.

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But when I clone the genes that enclose
the COP9 signalosome,

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I found that the CSN is

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not only found in arabodopsis,

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it's found fruit flies.

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And it's also found in humans.

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So of course the question is, why do fruit

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flies, and why do humans, have a COP9
signalosome?

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Now, I'm just going to take one more piece
of

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data to show you, or to, to describe to
you.

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So we've done similar experiments now
using

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fruit flies as a model system because

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I'm a big believer that through genetic

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analysis we can understand the basic
processes.

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So what have we done?

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We've taken fruit flies and I'll, how do I
draw

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a fly, okay, there's a wing, and there's
its head, okay.

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So this is my rough version of a fruit
fly.

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Before the fruit fly, it had what's called
a

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larva, it's like a little worm, and we
made

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mutations in the COP9 signalosome zone in
the fruit

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fly, and now you look at what phenotypes
they have.

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And when we looked in the larva

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of the CSN mutants, there's no COP9
signalosome in these mutants.

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What we saw is that they had black dots in
them,

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and when you dissect these black dots,
this is a type of fly leukemia.

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In other words, the COP9 signalosome in
flies affects cell division.

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It affects how the cells are dividing and
how they're differentiating.

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When there's a mutation, the cell division
doesn't

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occur in the right way, you get too

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much cell division, but the cells aren't
formed

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in the proper way and you get leukemia.

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We actually now know that the COP9
signalosome

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is involved in a number of human cancers.

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In Arabidopsis, of course there's

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no such thing as cancer.
There's no leukemia.

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But there we see the phenotype in

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photomorphogenesis, in how the plant
responds to light.

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So on a very basic level, what we see is
that a mutation

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in the COP9 signalosome affects the way

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a plant responds to the external
environment.

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because what did we say, what majorly
regulates a plant's development?

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The external environment.

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Because they're rooted, they have to be
aware of what's

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going on around us.
What regulates development in an animal?

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The internal environment.

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The internal clock.

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And so the phenotypes are internal
defense.

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Now let's go out into the lab where you
can

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see what some of the students are doing on
experiments today.

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Alright, so let's see what's going on in
this part of the lab.

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here we have a project that's going on.

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This is Manelli she's a masters student in
the lab.

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>> Hi
>> And what she has

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here is a Arabidopsis that are growing on
plates.

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And, what we're actually doing,

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>> This one's better.

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>> This one's better?
Thank you.

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Are looking for mutants that, whose roots
are

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longer under condition, than the wild type
r,

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and so what Manelli has actually been
doing

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for two years, is screening thousands and
thousands.

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>> Yeah.

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>> And thousands of these plants, in
order to find the mutants.

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Okay?
So over here, this is Ela.

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Ela is a PhD student in the lab, and

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right now Ela is not working on a wet
experiment.

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She's doing a dry experiment.

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A lot of our time is spent using

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computers, and what she's doing is she's
analyzing data

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of how genes are transcribed, how they're
turned on

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under different conditions, which
interests her in the lab.

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So she did the wet experiment a few weeks
ago, and

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now a lot of her work is spent analyzing
the data itself.

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Okay, let's see what's going

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on in the lab right now.

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this is the, actually the, more of the
office

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part of the lab, where we do the
administration.

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so now I've reached Muti ben, bench.

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Muti is a PhD student and as you can see,
she doesn't work with plants.

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Muti works with fruit flies.

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These are Drosophila, that are working
around.

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And what her research entails is trying

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to understand how the COP9 signalosome,
the CSN,

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influences gene transcription in these
lovely little organisms.

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So she works both with the flies and she
also works

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with cells of the flies, which we grow in
those things.