AP Biology class blog for discussing current research in Biology

Tag: cryptobiosis

Cancer-Causing Free Radicals Are the Key to Tardigrade Survival

Tardigrade (50594282802)

Many may recognize the resilience of tardigrades, the microscopic water bears that can seemingly endure any and all conditions—researchers have found that tardigrades possess this attribute because of their ability to harness free radicals, the infamous matter that causes cancer in humans.

Tardigrades have survived all five mass extinction events on Earth, and are thought to have been around since before the current eon. They can live through extreme temperature and radiation, and even the vacuum of space. But how are they capable of this immense resilience?

Traditionally, free radicals have been known to promote cancer, causing genetic mutations that allow cells to multiply uncontrollably. First, in mitosis, the mutated cell divides, then its offspring divides, and before long a mass forms. That mass, or tumor, grows uncontrollably, consuming vital nutrients and mechanically interfering with the body’s internal function. If left unchecked, the tumor will eventually overwhelm the body’s ability to survive. However, there’s a flip side to free radicals.

The tardigrade has managed to harness the destructive power of free radicals in its quest for survival. For years, scientists have been baffled by the tardigrade’s ability to undergo drastic transformation in times of extreme stress. The organism’s transformations are a part of cryptobiosis, which consists of (but is not limited to) anhydrobiosis and cryobiosis. In anhydrobiosis, the tardigrade decreases its water content by 99% and its metabolic rate by 99.99%, and remains in a “tun” state for five years or more, only to rehydrate and flourish once environmental conditions are back to normal. In addition, via cryobiosis and other cryptobiosis processes, the tardigrade can survive extreme heat (304° F) and cold (-458° F). And the trigger for all of these survival mechanisms: free radicals, the same extra-electron atoms and molecules that cause human cells to mutate and multiply to form tumors.

Recent research suggests that tardigrades initiate cryptobiosis and protect themselves by releasing intracellular reactive oxygen species (free radicals) that in turn reversibly oxidize cysteine, an amino acid that acts as a sort of regulatory sensor for responses to stressors. The obvious question is: why isn’t the tardigrade harmed by the free radicals? The answer might hold the key to better understanding how to prevent cellular mutation, and cancer, in humans. Additional investigation is needed in this area.

So, what do you think? Are there similar discoveries that may be able to help us combat cancer?

Tardigrades: the Superheroes of Biology

What is a Tardigrade?

Tardigrades are microscopic caterpillar-like creatures, sometimes called water bears, that are known to survive the extremes. Unfortunately, they look nothing like the Sea Bear from Spongebob, and a lot more like Rufus the Naked Mole Rat from Kim Possible.

Tardigrade (water bear)

Tardigrades are biological superheroes, capable of withstanding near total dehydration and even space vacuums. Tardigrades do something called cryptobiosis– a state in which metabolic activities are slowed and proteins and sugars are synthesized to protect the organism’s cells. This makes it possible for Tardigrades to live in extreme environments where other life forms fail to survive, such as deserts and polar regions.

Why do we care?

Scientists recently discovered a new Tardigrade superpower: Resistance to X-Ray radiation. This survival skill is due to one of the proteins synthesized during cryptobiosis: Dsup. A molecular biologist from the University of Tokyo (Takekazu Kunieda) led an experiment in which cultures of human cells were manipulated to have similar qualities to Tardigrade cells. These new cells were able to reduce radiation damage by 40%.

These new findings open the doors for improving the resistance to radiation in humans. One day, it could be safe for people to withstand extreme radiation, temperatures, or dehydration just like the Tardigrade does. Who would have thought that such a tiny organism had the potential to solve so many problems?


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