Prion diseases are neurodegenerative, attacking the brain. Could they be responsible for the recent wave of Zombie attacks across the globe? Original photo: digitalsextant. I’m a sucker for zombie movies; I’ve watched dozens of them. I am especially fond of the Resident Evil Trilogy, where the T-Viruses effectively restructure mortality and create a world of zombies. There is something incredibly satisfying with the zombie movie plot – a virus outbreak devastates a planet but a group of people are immune and fight to save humankind. Having the ultimate evil as a virus also makes it seem more plausible and compelling. Yet viruses and bacteria do not live in limbo. They are alive and under the right conditions can be killed. Which is bad news for Zombies.

But what if there existed a substance that acted like a virus or bacteria but wasn’t living? Medicine made a revolutionary leap during the time of Louis Pasteur in the mid 1800's. The inventor of food pasteurization and one of the founding fathers of microbiology – he was able to prove germ theory. Food spoiled and organisms got sick because of the growth of bacteria and viruses within them. Within sterile environments, viruses and bacteria could be killed off and food could be preserved or organisms could recover from illness or infection. Sterilization works on living micro-organisms. Prions, however, are not living organisms.

Prions are infectious proteins. For unknown reasons, these proteins refold abnormally and cause a domino effect in surrounding proteins which in turn mutate into stable structures. Prions will then cause tissue damage and cell death to surrounding areas. Prion diseases are neurodegenerative, attacking the brain and are characterized by "holes" in the tissue. The incubation time for Prion diseases is quite long. They usually surface later in life but after they surface, the diseases are rapid and fatal. Such examples of Prion diseases include Mad Cow Disease in cattle, Scrapie in sheep and Fatal Familial Insomnia in humans. FFI is a disease that literally takes away the ability to sleep and in a few months leads to death. The Book “The Family That Couldn’t Sleep” by journalist D.T. Max follows a family in Italy that passes this disease from one generation to the next over subsequent centuries.

Prions have been and still are a medical mystery. What causes them to mutate and aggressively eat away at the brain? How can they be stopped? Because they are not living they are highly resistant to sterilization methods. While viruses and bacteria can be eradicated on equipment through heat, radiation or chemical reagents, Prions are strongly immune. Maybe Zombies are not so far off after all – lurking in the shadow of medicine has been a mutation that is resistant, brain-eating and neither alive or dead. It has some serious similarities to the zombies I have watched over and over again on the big screen.

If you want to learn more about Prions and their history, check out Down to a Science’s next reading group which is focusing on the book The Family that Couldn’t Sleep or check out the book Deadly Feasts: The "Prion" Controversy and the Public's Health by Richard Rhodes. And one more thing – Happy Halloween!

Having extra copies of certain genes helps fish live in AntarcticaI've always loved weird creatures. Bacteria that can live in boiling mudpots. Weird tubeworms huddled around deep sea hydrothermal vents. Fish that live in below freezing water.

What I like is learning how these beasts have adapted to their incredibly harsh environment. More specifically, what changes have happened in their DNA that allow them to live where no other animal could.

In this blog I'll focus on those poor fish living in the waters off Antarctica. These waters are icy cold and the fish aren't warm blooded. Which means their body temperature is the same as the water around them.

Most biological processes do terribly under these conditions. Proteins don't fold right, enzymes work incredibly slowly, fats glob up. It is astonishing that these fish survive at all.

Scientists figured out back in the 70's that these fish evolved a special antifreeze protein to keep their blood from freezing. Since then they've done other experiments that show other adaptations to the cold too.

In a new study, scientists from the University of Illinois and the Chinese Academy of Sciences decided to take a look at as many genes and as much of the DNA of these fish as they could. What they found was that lots of genes are turned up in these fish compared to relatives that live in warmer waters. And that many of these genes are turned on higher because the Antarctic fish have extra copies of them.

The genes they found that were different made sense. For example, there are a bunch of genes that make proteins called chaperones. Chaperones help other proteins fold up right. In this cold, proteins need all the help they can get!

Also they found that there were more of the proteins that scavenge reactive oxygen species (ROS) in these fish. This makes sense because colder water has more oxygen.

O2 is a pretty nasty molecule that tends to create even nastier chemicals (ROS) that beat up on DNA and proteins. We all have proteins whose job it is to defuse these chemicals. These fish make more of these proteins.

A few years ago it would have been surprising to find that the way these genes made more proteins was by duplicating themselves. Not anymore.

As we look closely at the DNA of various creatures, we are finding that gene duplications (and deletions) happen a lot. Even in people.

For example, people from cultures that eat a lot of starch have extra amylase genes. (This gene makes amylase, a protein that helps breakdown starch.) Some people are resistant to HIV (the virus that causes AIDS) because they have extra copies of the CCL3L1 gene. And so on.

Our DNA is much less stable than we thought. Which is one way we can better adapt to our surroundings. I can't wait to see what they learn about those tubeworms!