Two adult tardigrades (microscopic creatures), called Acutuncus antarcticus, have been recently resuscitated after being frozen for more than thirty years, according to a new study. Scientists also managed to revive an Acutuncus antarcticus egg that was frozen alongside the two adult micro-animals.
In 1983, two mature Acutuncus antarcticus and an egg were collected from a piece of frozen moss in Antarctica. The moss was then kept frozen at about minus four degrees Fahrenheit (minus twenty degrees Celsius) for a lot of years.
During these years, the microscopic creatures have kept an ametabolic state of life, knows as cryptobiosis – in which the organisms showed no visible signs of life, and their metabolic processes appeared to have stopped, according to the scientists. The tardigrades were brought back to life after more than three decades.
The scientists rehydrated the creatures and saw that after only one day, one of the adult tardigrades was already stretching its tiny legs. They noted that after six days had passed from the beginning of the rehydration process, the same tardigrade was moving its body, trying to lift itself. About thirteen days later, the micro-animal was eating algae. Twenty-two days later, the scientists noticed that there were eggs inside the creature’s body.
The Acutuncus antarcticus laid a total of nineteen eggs, of which fourteen hatchlings emerged. These types of tardigrades reproduce through parthenogenesis, a natural form of asexual reproduction in which the embryos grow and develop without fertilisation.
Scientists said that the other Acutuncus antarcticus died without reproducing, and it only survived for twenty days after rehydration. However, the frozen eggs hatched, and its larvae eventually laid fifteen eggs, of which seven hatched.
Tardigrades, also known as water bears or moss piglets, are eight-legged creatures that live in algae-rich environments across the globe and measure approximately 0.02 inches (0.5 mm) in length. These tiny creatures have the ability to survive in harsh conditions – like extreme cold or heat – that would kill almost any other life-form. In 2007, tardigrades were launched in low-Earth orbit where they managed to survive by generating a protective coating.
Megumu Tsujimto, the lead researcher at National Institute of Polar Research, said that the ability of Acutuncus antarcticus to reproduce shortly after being brought to life from a thirty year deep freeze proves how durable these creatures are. It is also interesting how they manage to repair cellular and DNA damage, and how they are able to survive a deep-freeze recover, according to Tsujimto.
There are other small creatures that have similar preservation abilities. For instance, both larval and adult nematodes or roundworms – which are microscopic worms – have been revived after being refrigerated for more that thirty-nine years, the scientists said. Nematodes are a diverse animal phylum that can be found in a broad range of environments; there are over 25,000 species described, more than half of which are parasitic.
The findings were published on Tuesday (Feb. 16) in the online journal Cryobiology.
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