All life on Earth is dependent on the deoxyribonucleic acid and ribonucleic acid. The instructions for every living organisms are contained in the two building blocks. These are made up of five informational components, which are composed of organic molecule. Scientists have scoured meteorite samples for these building blocks.
The efforts have resulted in the detection of three of the five nucleobases. A recent analysis led by researchers from Hokkaido University, Japan has revealed the remaining two nucleobases that have been elusive to scientists. The ongoing debate about whether life on Earth emerged on its own or was assisted by organic compounds deposited by meteorites could be resolved by this discovery.
The leader of the research team was an associate professor at Hokkaido University. He was joined by researchers from the Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Tohoku University, Kyushu University, and the Solar System Exploration Division (SSED) at NASA. The paper about their findings was published in the journal Nature Communications.
The bases A, G, C, and T are found in DNA, while uracil is found in RNA. Scientists are unsure why more types haven't been found yet. Oba explained in a recent NASA press release.
“I wonder why purines and pyrimidines are exceptional in that they do not show structural diversity in carbonaceous meteorites unlike other classes of organic compounds such as amino acids and hydrocarbons. Since purines and pyrimidines can be synthesized in extraterrestrial environments, as has been demonstrated by our own study, one would expect to find a wide diversity of these organic molecules in meteorites.”
The newly discovered pair of nucleobases may have been elusive to scientists because they degraded before they could be removed. In earlier experiments, scientists put meteorite samples in a solution of hot formic acid and created a solution that they could analyze. Danny Glavin is a co-author of the book.
“We now have evidence that the complete set of nucleobases used in life today could have been available on Earth when life emerged. We study these water extracts since they contain the good stuff, ancient organic molecules that could have been key building blocks for the origin of life on Earth.”
The team used a cold brew instead of a hot tea approach for their study. The water used to extract the cytosine and thymine may have destroyed them in previous studies. The team was able to detect smaller amounts of molecule because of the more sensitive analytics they used. The team was able to detect fragile elements in their meteorite tea.
The debate about the completeness of the nucleobases that make up all life on Earth is not over yet. Scientists can't say for certain if life began in a pond billions of years ago or if it was assisted by organic molecule from space. Additional pieces of the puzzle have been provided by the detection of the remaining two nucleobases.
The team found traces of sugars and bases in the sample, indicating that more fundamental molecule of biology are found in space. The team's research resulted in a new proof of concept technique that has proven more effective at getting information from asteroids. When NASA returns samples from the asteroid Bennu next year, this will come in handy.
Nature Communications and NASA are further reading.
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