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Fluorescent glow may reveal hidden life in the cosmos

Fluorescent glow may reveal hidden life in the cosmos

Astronomers seeking life on distant planets may want to go for the glow.

Harsh ultraviolet radiation flares from red suns, once thought to destroy surface life on planets, might help uncover hidden biospheres. Their radiation could trigger a protective glow from life on exoplanets called biofluorescence, according to new Cornell research.

Biofluorescent Worlds II: Biological Fluorescence Induced by Stellar UV Flares, a New Temporal Biosignature” was published Aug. 13 in Monthly Notices of the Royal Astronomical Society.

“This is a completely novel way to search for life in the universe. Just imagine an alien world glowing softly in a powerful telescope,” said lead author Jack O’Malley-James, a researcher at Cornell’s Carl Sagan Institute.

“On Earth, there are some undersea coral that use biofluorescence to render the sun’s harmful ultraviolet radiation into harmless visible wavelengths, creating a beautiful radiance. Maybe such life forms can exist on other worlds too, leaving us a telltale sign to spot them,” said co-author Lisa Kaltenegger, associate professor of astronomy and director of the Carl Sagan Institute

Astronomers generally agree that a large fraction of exoplanets – planets beyond our solar system – reside in the habitable zone of M-type stars, the most plentiful kinds of stars in the universe. M-type stars frequently flare, and when those ultraviolet flares strike their planets, biofluorescence could paint these worlds in beautiful colors. The next generation of Earth- or space-based telescopes can detect the glowing exoplanets, if they exist in the cosmos.

Ultraviolet rays can get absorbed into longer, safer wavelengths through a process called “photoprotective biofluorescence,” and that mechanism leaves a specific sign for which astronomers can search.

“Such biofluorescence could expose hidden biospheres on new worlds through their temporary glow, when a flare from a star hits the planet,” said Kaltenegger.

The astronomers used emission characteristics of common coral fluorescent pigments from Earth to create model spectra and colors for planets orbiting active M stars to mimic the strength of the signal and whether it could be detected for life.

In 2016, astronomers found a rocky exoplanet named Proxima b – a potentially habitable world orbiting the active M star Proxima Centauri, Earth’s closes star beyond the sun – that might qualify as a target. Proxima b is also one of the most optimal far-future travel destinations.

Said O’Malley-James: “These biotic kinds of exoplanets are very good targets in our search for exoplanets, and these luminescent wonders are among our best bets for finding life on exoplanets.”

Large, land-based telescopes that are being developed now for 10 to 20 years into the future may be able to spot this glow.

“It is a great target for the next generation of big telescopes, which can catch enough light from small planets to analyze it for signs of life, like the Extremely Large Telescope in Chile,” Kaltenegger said.

Aequorea victoria ventral view

Researchers identify fluorescent proteins in the body of jellyfish for the first time

This jellyfish makes glowing proteins which were previously unknown to scientists. Nathan Shaner and his colleagues back in 2017 had found something unusual near Herons land. They were snorkeling through the southern coasts of Australia near the Great Barrier Reef and spotted a strange-looking jellyfish. Scientists took the jellyfish and bought it back to the boat and after having a closer look it came to notice that the translucent body of the fish had shot through luminous lines of blue.

Shaner, an optical probe developer at the University of California collected the animal due to his wish as it was blue and wanted to take it home but the team was not looking primarily for jellies however came across one. The team identified the five fluorescent proteins in the body of the jellyfish which were previously unknown. This may lead to the discovery of newer techniques for exploring how genes are expressed in cells and gain the brightest fluorescent protein tag.

Shaner and his team went back to the lab and prepared a sample for analysis and after sequencing its transcriptome, the genes present in the jelly’s body, he was surprised to find several light-producing proteins similar to green fluorescent protein which was being used by scientists for decades to track cell protein and make glow-in-the-dark cats.

The original protein known as avGEP has led to dozens of bioengineered GFP variants, some of the variants glow in colors like cobalt blue and turquoise. Further analysis revealed that jelly A.australis produces five fluorescent proteins which include two which glow green, two more that are blue and one between yellow and clear when exposed to light. When researchers looked at the original GPF jelly once again, they found genes of previously unknown fluorescent proteins, some had narrow excitation and emission peaks from which they could absorb and emit light at a specified wavelength. It helped in the study of the expression of several genes simultaneously with the help of colors of fluorescent protein tags. AausFP1, the brightest protein was almost five times brighter than GFP, which was enhanced for powerful fluorescence.

Fluorescent proteins have different use depending on what we are trying to study and the brighter the better for everyone as it will hopefully enable people to see things that could not be seen before. AausFP1 is bright and does not lose its glow when exposed to light and can be used for cell imaging for extended amounts of time for continuously up to 2.5 days where normal GFP variant would bleach within few hours.

Joachim Goedhart, a fluorescent protein engineer at the University of Amsterdam says the study is exciting and researchers came back with different variants and that fluorescent protein needs modifications for being useful. Mutations would be required for smaller, brighter and easier manipulations in the cell.

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