Salk scientists see 3D structure of DNA in cells for first time


(simple, wondering piano music) – The genome is the same
in every cell in your body. But only certain genes
are on in each cell. So, obviously, it’s not the sequence, but it’s the structure of
these genes in each cell that determines if they
can be accessed and used. So the question is then what is the structure that determines if genes can be accessed and used. That really is what makes
the brain cell a brain cell and a muscle cell a muscle cell. And also, every human being different. And so, what we’re really
trying to understand is the local structure and the global 3D organization, both in the nucleus and
when it gets inherited across cell division
in mitotic chromosomes. What are those structures? How do we inherit information? And if we understand the structures, can we now begin to
actually manipulate it? To impart new functions? And actually cure intractable diseases. One of the challenges really of biology is trying to be able to see a structure in as, what’s called, as
natural a state as possible. And so, how do you see
it without disturbing it? – Chromatin is how the genome is organized inside the cell. For a long time, people
were able to basically study chromatin structure by
electron microscopy. However, what people do
is they have to basically take the cell, and break apart the cell, and look at the chromatin structure. What is the chromatin
structure inside intact cell? And can we find a method or a
technique that can enable us to visualize chromatin
structure in a cell? – So what we did is we identified a fluorescent DNA-binding dye, that when you shine light on it, it has this really amazing property, which is that it
catalyzes a metal polymer, a cast, across the surface
of DNA and chromatin in the nucleus that
enables it to be visualized in the electron microscope. Life occurs in 3D, right. Form gives way to function. And so, the new technique
really allows you to reconstruct the three
dimensional structure, those shapes, those surfaces that catalyze, that determine, I mean physically, if genes
could be accessed or used. And you can visualize it as a continuum, and take a trip sort of
from the top to the bottom of the nucleus. And you see its structure as, basically, an enzyme would see it. As a transcription factor would see it As a virus would see it. So, really being able to see now the fine structure and
global 3D organization of DNA could really enable us to design drugs that change its structure and organization to make a tumor cell remember how to be normal again. And to impart new functions
that improve and change the human condition, right. Because when you see something, you begin to understand
in an entirely new way. It’s really exciting actually.

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