Various species ranging from microscopic bacteria to birds have naturally occurring fluorescence or emission of electromagnetic radiation. Scientists have discovered a new species of tardigrade, a microscopic animal that protects itself from ultraviolet light.
The study by researchers from the Indian Institute of Science was published in the journal Biology Letters. The tardigrade was observed to glow blue when exposed to radiation, shared the scientists.
Tardigrades, also called moss piglets or water bears, are a microscopic species that can survive various harsh conditions such as radiation, dehydration, and extreme temperatures or pressure. Four years ago, Japanese scientists revived a tardigrade that was frozen for several decades. They can also survive 30 years without food or water while living in extreme environments.
Survival Methods of Tardigrades
The animal has eight legs and is related to grasshoppers and the praying mantis. There are nearly 1,300 species of extremophile tardigrades around the world.
They possess unique proteins called damage suppressors. Also known as Dsup, the proteins protect the DNA from harm such as radiation from the environment.
They can also become dormant for a long time through a state called cryptobiosis. The metabolic state is a response to extreme environmental conditions such as lack of oxygen.
Some tardigrade species can also produce asexually. Eggs may hatch after 40 days or twice that long if the tardigrade underwent a desiccated state.
Protection Against Radiation
During the study, tardigrades were extracted from the moss that grew on a concrete wall. The tiny animals were then exposed to ultraviolet light using a germicidal lamp. After 24 hours, all the various species died except for one group of tardigrades.
Biochemist Sandeep Eswarappa and the team exposed the remaining tardigrades to another hour of radiation. 60% of the creatures survived for survived an entire month after exposure to a dose of UV light that is used to kill bacteria and nematode worms within minutes.
The team was sure that they discovered a new species under the genus Paramacrobiotus. 'After UV radiation treatment, tardigrades were observed daily for signs of life-active movement and egg-laying," they wrote. There were no changes in how many eggs they laid or hatchability compared to pre-radiation exposure.
Under an inverted fluorescence microscope, the new reddish-brown tardigrade species emitted a blue light. The team speculated that its skin fluorescence, also called autofluorescence, could be protecting the creature against radiation exposure.
Next, the team took some of the tardigrade pigment and covered nematode worms and Hypsibius exemplaris tardigrades, which died in the first UV light experiment. The fluorescence of the new tardigrade species proved to be a protective shield against radiation.
The team demonstrated that fluorescent extract could transfer protection from the new strain of tardigrades to other species that are more sensitive to radiation. The autofluorescence of the tardigrades demonstrate "exceptional tolerance to UV radiation," concluded the authors.
Other species that have autofluorescence include scorpions, parrots, chameleons, and frogs. Scientists have also suspected that corals and comb jellies may also possess fluorescence properties.
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