So, how in the world do cells glow green?
Well, first off, well the secret to this answer is that the answer is actually
going to be GFP, but before we go even further, lets kind walk through,
what exactly do I mean by cells.
Well, we know that our body is made up of cells, different types of cells.
We also know that living things are made up of cells, for instance, plants are made
up of cells. Actually, every living thing is made up of cells.
And different cells perform different functions.
So, inside of your human body, we have these cells.
And they are often represented by cartoons like this. Our cell here has a boundary layer
or a wall, that contains all the important compartments of the cell inside.
One really important compartment is the nucleus of the cell,
which is shown in the center.
This nucleus contains all of the important information for the cell to do its job.
You can think of it like a library. It contains all of the important books for
the cell to move, to use energy, to even make copies of itself. You can even think
of it like Google, it contains all of the important things that the cell needs
to do its job well. So, within this library, within this nucleus, is DNA, or genes.
You can kind think of them as books, or blueprints. Its these genes, or DNA, that
help make proteins, which are the tools that cells use to actually do their job.
So we have our cell here. It contains our nucleus which contains our DNA which
is the books that are used to make the proteins that are important for the cell doing its job.
This is a very lovely picture. Very lovely cartoon.
How could we see a cell in real life? Well, we would need a microscope.
Maybe you've seen this microscope before. This is a light microscope.
You might have seen it in lab or at school, or maybe on a TV show.
It uses magnification to help us see small items like cells.
Here's actually a picture of cells. And we can see some pretty interesting things.
We can see the cell wall, that kind of is outlined here. We can maybe
see maybe the nucleus, but it's actually really hard to tell what is going on.
It's just black and white to us. What if we had a tool to help us
see more clearly what was happening inside these cells. That's where green comes in.
To help me explain this. I'm going to show this cool video.
It's about two minutes long. That's going to explain all about the green, the GFP.
So I hope you enjoy it.
Microscopes are an essential tool for biologists to see the tiny things they study.
But no matter how much you zoom in with a microscope, some things are just really hard to see.
There's those technical difficulties I was talking about. I'm gonna try one more time.
This is partly because when you look at something under a microscope,
a lot of things are pretty much the same color.
This is where fluorescence microscopy comes in. More than 50 years ago,
scientists found a special protein in some jellyfish that make them glow under
ultraviolet light. This protein named green fluorescent protein, or GFP,
changes shape when hit by the right color of light. This change in structure it makes
GFP fluoresce, it absorbs ultraviolet light and shines out green light.
By this discovery, the way scientists use microscopy was changed forever.
How? Well you might be familiar with a traditional light microscope.
You've got your sample on a stage, a Bumblebee in this case, and a lamp sends
white light up through the stage to your eye
with some lenses for magnification in between.
But now we want to specifically look at the brain of this Bumblebee.
With light microscopy, we can't really tell the difference between different structures.
So let's take a different Bumblebee. One where we've labeled the brain with GFP.
Under white light, it doesn't look like much, but now we add a filter that only lets
the right wavelength or color of light through. GFP absorbs this color of light and glows.
To make the picture as clear as possible we add one more filter,
so only the green light reaches our eyes. And now we can see the bumblebee brain
as clear as day. Since the discovery of GFP, a whole rainbow of different fluorescent
proteins have been engineered. Red, orange, yellow, blue and more.
By using multiple fluorescent proteins to color different parts of the sample,
we can very clearly see whatever it is we might be looking for.
Awesome, awesome. So, now we can answer this question, right?
How do cells glow green? Well, the answer is GFP, green fluorescent protein.
Its how we can get these beautiful pictures of cells like you see here, and actually is
what can be really useful as a tool for scientists who wants to study more
about what's inside a cell. And so actually, what I do, the research that I do, uses
these tools, these green fluorescent proteins, to see what's happening inside viruses.
So, and I use these fluorescent proteins to help me see what's going on inside.
Viruses are a type of cell. We have been hearing a lot about viruses
in the news recently.
There are different types of viruses and a really important one is bacteriophages,
which I show here. Viruses work by entering into the cell through the wall,
the cell well that I mentioned earlier. And it hijacks the library, or the nucleus,
of the cell to create copies of itself.
You can think of a virus like a cloning machine, it uses the proteins of
the host cell to make copies or clones of itself, which then can use to spread
to other cells. I work on a particular virus called HIV,
or Human Immunodeficiency Virus. It looks a little different than the
bacteriophage, but it operates in the same way, it hijacks a healthy cell to make copies of itself.
So HIV doesn't currently have a cure. The issue for why we don't have a cure yet
for HIV is that some viruses enter into the cell and make copies of themselves,
whereas others enter into the cell and don't do anything at all.
You can think of it kind of like a stoplight. Um, some cells enter into the cell and get
a red signal and don't go, they have a red light.
Whereas some viruses enter into the cell and get the green light and replicate
and make many copies of themselves. And so, right now, researchers don't understand
why some cells have a red light, and some cells have a green light. And so I'm trying
to understand how the red light changes to a green light.
And I use fluorescence microscopy to do it. Here are two pictures of the same four cells.
I use purple fluorescence protein to make the HIV viruses appear in my cells.
So if you can see my mouse here, I have these very small purple spots.
This represents a virus, a cell that has virus inside it so the cell is outlined,
we can see the cell wall and then inside we can see the individual viruses.
And this cell has virus that has received the green light and so its made a lot
of these viruses, and some cells don't have any virus in them at all,
even though it should be there. And so I'm trying to understand how can I
how can I change the green light to a red light or the red light to a green light.
And so I designed computer experiments on my computer to see if I can change that light.
And then I use fluorescence microscopy like I showed here, to see if it works.
So GFP is very useful. It makes cells glow green, and actually, it's helping us
find a cure for HIV. And honestly, there might be even more things that
we could use GFP for in the future. Honestly, the possibilities are endless.
So now that I've answered these two questions, perhaps, about why cells
glow green and, perhaps, trying to figure out the question to how to cure HIV,
I want to hear your questions. Do you have any questions about biomedical
engineering or about biology or about green fluorescent proteins?
Let me hear your questions. And so right now, if you have any questions,
feel free to put them into the chat. And my lovely MC Emily is going to be looking
and seeing if there's any good questions for me to answer.
[Emily] Hi, Elise, and Hi, everyone else. Yes, Elise, you've gotten some questions.
So the, I guess I'll start with the ones submitted in the chat. Oh, and we still
have still some coming in. So someone wants to know,
Does HIV specifically target cells?
[Elise] Oh, yeah, that's a great question. Um, so the version of the virus
that I work with, does only target cells. It really, the virus really wants to make
copies of itself, for it to survive. And for it to continue to thrive, it really
needs to find a host to be able to infect and then to be able to make copies of itself.
So then it can send out and find more cells to infect. That's a great question.
[Emily] Right, and our next question is, um, would GFP alter some protein balances
inside of a cell?
[Elise] So the question is kind of referring to, so GFP, green fluorescent protein,
is a protein itself. And so whenever we make cells glow green, it's because
we're making lots of this GFP, lots of this protein from, remember it comes
from that nucleus, which includes all those books of the genes.
And so we are telling the cell to make a lot of a certain type of book or certain type
of protein, specifically GFP to, for instance, get pictures like this. And,
so whenever we maybe make too much GFP, it can actually start to hinder the production
of other proteins. And you can kind of think of it like, let's say you are baking a cake.
And so for a cake, you need eggs, you need flour, you need sugar. If you make a lot
of one type of cake, you're going to use up all of your eggs, your flour, your sugar,
so you can't make pancakes later. And so sometimes if we make too much GFP,
we can actually affect the the production of other important proteins.
So that's a great question.
[Emily] All right, and some people are curious about whether you can
elaborate on how HIV works and also are there different different types of HIV.
[Elise] Hmm, yes. So, for the first question, there are some different types of HIV.
Just like there are different types of bacteriophages. And some of the different
viruses that we've been hearing about, there are different types.
Some HIV viruses infect humans. Some have some effects for animals as well.
So I'm specifically looking at human derived HIV that can only infect humans,
and some primates. And so for how HIV works, so it works very much like a virus.
So it was that virus diagram I showed at the beginning, it can enter in to a host cell
of a healthy cell from a human. It hijacks the area in the nucleus. So actually
what it does is that it takes itself and actually inserts itself almost like a book.
It takes its own genetic information and inserts itself into the nucleus of the host cell.
So you can kind of think of it like, you have a book and you take it to the library
and put it on the bookshelf. And then what happens is that when the cell starts
to make proteins, just a normal job it would do every day. And it takes that book and says,
Oh, I need to make this protein, and so it makes more copies of the HIV virus.
And what happens then, is that as the HIV virus accumulates in the cells,
and more spills, more viruses go out to infect other cells. That can be really bad
for healthy cells, healthy cells get infected and they start to die off.
This is really bad, especially if the healthy cells that they're infecting
are your immune cells. So I mentioned the beginning that a human body has
lots of different types of cells, we have skin cells, we have neurons,
a type of cell that we have is called an immune cells and it's what keeps us healthy.
It's our immune system. And so when you start to infect, cells that are supposed
to keep you healthy, it can be really bad and can make people really sick.
And so often times people who have HIV, might contract other infections later on.
Because the cells that are supposed to keep them healthy are sick themselves.
We can kind of think of it like, if, for instance, if you have a doctor
and a doctor might get sick, he can't take care of his patients as well anymore.
And so keeping the doctor healthy is important. And you can kind of think
of it like that.
[Emily] All right.