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The Tagish Lake meteorite fell in northern British Columbia on Jan. 18, 2000. It produced a remarkable fireball as it streaked across the dawn sky, which was witnessed as far away as Whitehorse, Yukon. (Royal Ontario Museum)
Meteorites that have affected Earth within the recent years have given a remarkable invention: they have all five of the bases responsible for storing genetic information in DNA and RNA. This amazing discovery, reported by researchers in Nature Communications on April 26, gives important insights into the origins of life on our planet.
The five nucleobases in question – adenine, guanine, cytosine, thymine, and uracil – are basic components of the genetic code present in all types of life known on Earth. The mystery of whether these important building blocks of origin of life in space or created by the intricate chemistry of our planet has long intrigued scientists. While this invention doesn’t surely answer that question, it significantly empower the hypothesis that life’s precursors may have their roots beyond Earth.
Researchers have been finding traces of adenine, guanine, and other organic compounds in meteorites since the 1960s. However, the existence of uracil, cytosine, and thymine had left elusive until now. According to astrochemist Daniel Glavin from NASA’s Goddard Space Flight Center in Greenbelt, Maryland, “We’ve done all the bases found in DNA and RNA and life on Earth, and they exist in meteorites.”
The development became possible by a novel extraction method developed by geochemist Yasuhiro Oba and colleagues at Hokkaido University in Sapporo, Japan. This technique softly extracts and detach several chemical compounds from liquified meteorite dust, enabling precise analysis. Notably, this method has more sensitivity than old methods.
Recently, Oba’s team used this method to find ribose, a sugar need for life, in three different meteorites. In their newest study, they collaborated with NASA astrochemists to study four meteorite samples, along with one of those recently discovered to contain ribose. With the help of their innovative extraction perspective, they quantified the abundances of nucleobases and another life-related compounds in meteorites that fell many years ago in Australia, Kentucky, and British Columbia.
The results were shocking. In all four meteorite samples, the scientists founded and measured adenine, guanine, cytosine, uracil, thymine, as well as various compounds are very relatable to these bases and a handful of amino acids. The method’s mild extraction process, with cold water than harsh acids, contribute in preserving these fragile nucleobases, making it more akin to a cold brew than a hot tea.
