Hi. It's Mr. Andersen and welcome to biology essentials video 39. This is how
changes in signal transduction pathways can have huge effects. So I'm going to talk about
poisons and diseases. But I wanted to start with one of the most dangerous animals that
we have on our planet. It's the California Newt. California Newt you could pick it up.
You could hold it. It's no big deal. But if you were to eat it, you would die just within
a few hours. And that's because the California Newt produces a toxin on its skin. We use
to think the newt produced it but we now know that it's a symbiotic bacteria that's producing
this toxin. It's called tetrodotoxin. It's one of the nastiest neurotoxins that we've
ever found. It effects the sodium ion channels in the nerves. And so what it does is shuts
them down. Our nerves can't work correctly. So those cells don't work. And then we can't
breathe and we die as a result of that. Tetrodotoxin is found in lots of other animals. So puffer
fish, if you're familiar with that, in Japan hundreds of people die from puffer fish poisoning
each year. Or some of the cephalopods like some of the really toxic octopi also have
this tetrodotoxin inside it and shuts them down. It also goes by another name. And that's
called voodoo powder. Or Zombie powder. If you want to google tetrodotoxin you'll find
the story of a Haitian zombie that was created through voodoo processes. And I don't really
believe, yeah I do, I do believe in zombies and they're coming so watch out for that.
But it's kind of an interesting story of how they took this one person, fed him some tetrodotoxin
poison and supposedly kept him as a zombie for years. Interesting story. True? Who knows.
So let's start with signal transduction pathways. So again, if you don't know what that is,
make sure you watch the video on that. Essentially what happens is the messenger will dock, a
ligand will dock with the receptor. It transduces that message. It sends it to a number of secondary
messages and then it targets parts of the cell. So it has an action within the cell.
So it's a great way to send the message into the cell and also amplify that message. Now
signal transduction pathways can have disruption. So whenever you have a series of events you
can also have a series of unfortunate events. In other words we can have blockage along
this way and that can have huge consequences. So the two cases I'll talk about is anthrax
poisoning and how that effects a protein in a specific signal transduction pathway. And
then one you're maybe a little bit more familiar with. And that is diabetes mellitus or regular
just diabetes. So let's start with anthrax poisoning. Anthrax was in the headlines years
ago, post 9-11. And what was happening was somebody was sending anthrax spores. Anthrax
spores are essentially bacteria that have dried up. They just have their genetic material
inside there and then their just waiting. So if you breathe in anthrax, it goes into
your lungs. And then this bacteria starts to grow. So this is bacillus anthracis, will
start to grow. It feeds on your lungs. And it produces a toxin. And that toxin can disrupt
cells and eventually can cause death as a result of that. And so how does that work?
How does that effect us? Well, when I talked about the signal transduction pathways, the
one that you're probably familiar with was how a ligand can bind to the G protein. That
G protein can eventually release an alpha subunit which then makes cyclic AMP. Cyclic
AMP is a secondary message. We can amplify a message and then we can target parts within
the cell. Now what we've started to realize is that poison found within anthrax actually
targets this enzyme, adenylate, or adenalyl cyclase. And so it changes the shape of this.
So it changes the shape of this protein. It now can't convert ATP into cyclic AMP. And
so that is the way that that anthrax poison actually works. It's just blocking a part
of this signal transduction pathway. And then it has huge consequences just in the cells
in which it effects. Another one you're maybe more familiar with is diabetes. Diabetes uses
a signal transduction pathway. Not diabetes but there is a signal transduction pathway
inside all of the cells in our body. So we have an insulin receptor. An insulin receptor
is going to sit on the surface of your cells. And when insulin docks with that, it has a
series of events that go on within the cell. So what are some of the events? Well it's
going to effect this glucose transport. So I like the name of that. That's just called
GLUT. And GLUT is going to allow a cell to take in glucose. Make use of it. Store it
as glycogen or make use of it inside the cell. And so if you have type I diabetes, what's
going on there, well if you have type I diabetes, you're not producing insulin. You're not producing
insulin. Therefore it can't dock with that insulin receptor. And so that's why you have
to get insulin shots. Here would be a pump working. And that's essentially producing
insulin within the body so we can so we can actually set up this signal transduction pathway.
If you have type II diabetes, type II diabetes is actually effecting the insulin. You're
still making insulin inside your body but that insulin receptor is ignoring that message
coming from the insulin. And so that's going to disrupt the signal transduction pathway.
We can't inactivate the GLUT. We can't take in the glucose as well. And so again signal
transduction pathways are awesome. It's a great way we can transduce a message. We can
amplify that message, but it's also a great place to target as far as diseases and poisons
and toxins. And so I hope that's helpful.