. Life may have started spontaneously in four billion years from DNA fragments that self-organized. Although scientists have a good understanding of single-celled organisms that date back about 3.5 billion to 3.8 million years ago, they don’t know much about their origins. Researchers led by Tommaso Bellini from the University of Milan suggest that DNA-like molecular pieces may have evolved self-organizing properties around four billion years ago to form repeating chemical chains, which could then be used as the foundation for primitive life. This latest research has been published in Nature Communications, citation below. One droplet of nano-DNA condensed within it and smaller drops from its liquid crystal phase, which are visible in the polarized sunlight on the left. These liquid crystal drops act as micro-reactors, allowing short DNA to be joined together in long polymer chains by themselves without any biological mechanism. Image courtesy of Noel Clark at University of Colorado. Neol Clark (physics professor) says that the findings are a new scenario regarding the non-biological origins of the nucleic acid building blocks of all living organisms. There are four types of nucleic acids: DNA, RNA (mRNA), tRNA and mRNA. The 1980s was where CU-Boulder Nobel Laureate, Distinguished Professor Tom Cech, and his colleagues found that RNA can chemically modify its structure. This led to the creation of the idea of an RNA world in which primordial existence could be a collection of RNA chains that are able to create other chains using simpler molecules in the environment. The new discoveries offer an alternative way to the origin of life. While many scientists believe that the RNA chains were created by random chemical reactions, Prof. Clark said the findings are a feasible alternative. The latest research showed that micro-DNA fragments that are only a few nanometers long can spontaneously be assembled into liquid crystal phases. This allows for the formation of chemical bonds, which connect short DNA chains together to create longer ones. The liquid crystals can be substances that flow as a liquid, but still have some order in their molecular arrangement. Although they can flow as a liquid, their molecules have a more crystal-like orientation. Professor Clark stated that “our observations are suggestive” of the events on Earth four billion years ago when DNA was discovered. The team spent years studying the possibility that DNA’s structure and ability to self-organize is the key. Pre-RNA Earth’s spontaneous assembly of nucleic acids fragments (RNA, DNA), may have served as a template to their chemical joining into polymers. Polymers are molecules that have molecular structures made up mainly, or entirely, from a number of closely related units bonded together. A large number repeating units. Professor Clark stated: “The new results show that, in the presence of the appropriate chemical conditions,” the spontaneous self-assembly small DNA fragments into stacks containing short duplexes favors their binding to longer polymers. This is a pre-RNA route. Nature Communications. DOI: 10. 1038/ncomms7424.
