Whoa, this leech survived after being in liquid nitrogen for 24 hours

Scientists have learned that a common parasite of sea turtles is capable of surviving ridiculously cold temperatures — a finding that could lead to the development of advanced cryopreservation techniques.

Okay, gotta say, this thing's really weird. Most organisms cannot survive exposure to temperatures below 0°C, let alone temperatures as low as liquid nitrogen. Once you get below the freezing point the water in the cells cause way too much damage, typically resulting in cell death.

What's even weirder is that this leech, Ozobranchus jantseanus, parasitizes sea turtles that swim in waters no colder than −2 to −4°C, and for more longer than 11 days. "It is likely," write the researchers in their study, "that this cryotolerant ability has arisen in response to some as yet unclarified adaptation."

And an extreme adaptation is it. The leech can survive exposure to super-low temperatures by storage in liquid nitrogen (−196°C) for 24 hours, as well as long-term storage at temperatures as low as −90°C for up to 32 months. The leech is also capable of enduring repeated freeze-thaw cycles in the temperature range 20°C to −100°C and then back to 20°C.

The researchers, a team lead by Dai Suzuki, say it's a wider temperature range than anything ever seen before in a cryobiotic organism. Some nematode worms, for example, can survive 28 days when exposed to temperatures as low as −80°C.

Interestingly, the researchers did not find any traces of trehalose or glycerol in O. jantseanus, both of which are typical and well known cryoprotectants. What's more, the leech didn't have enough time to enter into a state of super-dehydration — a common technique for surviving cold temperatures. Instead, the scientists speculate that the parasite has evolved a highly specialized — and largely unknown — way of tolerating physiological water freezing in their tissues; they have somehow evolved an innate capacity for withstanding such cold stresses.

The scientists say these findings could contribute to the development of new cryopreservation methods that don't require additives, and help resuscitate organisms that have been frozen underground in permafrost areas, on Antarctica — and possibly on other planets.

Or, it could help us improve current cryonic techniques for storing humans.

Read the entire study at PLoS: "A Leech Capable of Surviving Exposure to Extremely Low Temperatures."

Image: Suzuki et al.
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