Our next presenter
is Emma Kowal. Emma is a graduate student
in Chris Burge's lab. She grew up in Toronto and
did her undergraduate work in chemical and physical
biology at Harvard before crossing vast
distances to come to MIT. Her dream was to
write science fiction and so she decided she'd
better study science so she would know what to write about. The title of Emma's talk
is "Gone but not Forgotten: How do Introns Enhance
Gene Expression?" Emma. [APPLAUSE] Ask a biologist how cells
turn DNA in
to protein and I bet they'll say to you,
oh yeah, we know how that works. Imagine you're a cell
and I'm your DNA. I'm going to hand you a 10-page
instruction manual on how to build some protein. But before I give
it to you, I'm going to rip out nine of the pages
and say, oh, you actually need that one. That's how human genes work. They synthesize a
whole big long message and then throw away most
of it before it actually gets to the protein
factory, the ribosome. So, now knowing that,
imagine I'm
the cell and you're a
molecular biologist. Say you want me to make
a ton of some protein. Maybe you want to study it. Maybe you want to
use it as a drug. What are you going to do? You're going to give
me a ton of DNA, right? But hey, you're scientists. You're clever. You're not going
to waste your time making that whole big long
message when most of it's just going to get
thrown away, right? You could just give me
the little pieces that go to the ribosome,
called the exons, and that should work
, right? Well in that case, I, the
cell, would turn around and say, here's your
protein, smart ass, and just give you a little
bit or sometimes none at all. What's up with that? Well you should have
given me the whole gene, because those bits that get cut
out, they're called introns. And it turns out that even
though they don't contain instructions on how
to build a protein, even though they literally get
destroyed seconds after they're built in the cell,
most genes need at least one intron for
effective protein production. How is this possible? Well that's what I'm going
to try and figure out. One question that
you might start with is, does it matter
what's in the intron? Does the intron
sequence matter or is it just ripping something out
that's important for the cell? Well now picture two cells. You give them the same gene -- same exons -- two
different introns. Cell 1 gets intron A,
Cell 2 gets intron B. Who makes more protein? Well people have
done this experiment and you know what
they saw? Sometimes it doesn't
really matter. Sometimes one intron will give
you 500 times more protein than the other. So here's my plan. Instead of two cells, I'm
going to take a million cells. I'm going to give them
each the same gene with a different intron. A million different introns,
each with a unique, randomly generated sequence. Then I'm going to measure and
see who makes the most protein and what intron
sequences differentiate the strong introns
from the weak. Because what I want is
like a Rosetta Stone for the intron code. I want to learn a few
words of their language and then use them to ask what
introns are up to in the cell. Who are their partners in crime? What mysterious
chemistry allows them to speed up production
in a factory that they will never touch? Because I think the
problem is, we already speak the language of exons. We know the genetic code, how DNA goes to protein, whatever. We think that's the
whole story, but we have no idea what
those introns might be wh
ispering in the
ear of the ribosome long after they're gone. And I think it's about time
we started to listen, because I bet they have a lot to say. Thank you. [APPLAUSE]
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