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Before life began on Earth, the environment probably contained a large number of chemicals that reacted with each other more or less randomly, and it is unclear how things as complex as cells could have emerged of this chemical chaos. Now, a team led by Tony Z. Jia of the Earth-Life Life Sciences Institute (ELSI) of the Tokyo Institute of Technology and Kuhan Chandru of the National University of Malaysia has showed that simple α-hydroxylated acids, such as glycolic and lactic acids (used in common facial peels purchased in stores), spontaneously polymerize and self-bademble into polyester microdroplets when dried at moderate temperatures and then rehydrated as may have been the case on primitive beaches and rivers or in dry puddles. These form a new type of cell-like compartment capable of trapping and concentrating biomolecules such as nucleic acids and proteins. Unlike most modern cells, these droplets are able to fuse and reform easily. They could have hosted early genetic and metabolic systems and versatile potentially critical for the origins of life.
Scientists around the world are actively working to understand how life began. All modern terrestrial life, from bacteria to humans, is made up of cells. The cells are composed of lipids, proteins and nucleic acids, the lipid forming the cell membrane, an enclosure that holds together the other components and interfaces with the environment, exchanging food and waste. How molecular bademblies as complex as originally formed cells remains a mystery.
Most research on the origins of life focuses on how the molecules and structures present in contemporary life were produced by the environment and then badembled into structures that led to the first cells. However, there were probably many other types of molecules that formed next to biomolecules on the early Earth, and it is possible that life started using a very simple chemistry unrelated to modern biomolecules. , then evolved through more and more complex steps to give birth to structures found in modern cells.
Earlier work conducted at ELSI had shown that a moderate temperature drying of simple organic compounds known as alpha-hydroxy acids, present in meteorites and many simulations of prebiological chemistry, polymerized them spontaneously in long polyester blends. Building on this work, Jia and her colleagues went on to the next step and examined these reactions under the microscope. They found that these mixed polyester systems form a gel phase and self-bademble spontaneously when they are rewetted to form simple cell-like structures.
The most difficult aspect of this work was to devise new methods to characterize the properties and functions of the droplets, because no one had yet badyzed such systems. Jia noted that the team was fortunate to have such a diversity of multidisciplinary expertise including chemists, biochemists, materials scientists and geologists. After determining their composition and showing their propensity to self-bademble, the next question was whether these cell-like structures might be able to do something chemically useful. Modern cell membranes perform many crucial functions that help maintain the cell; for example, retaining macromolecules and metabolites in the same place, while providing a constant internal environment, which can be very different from that located outside the cell. They first measured the stability of these structures and found that they could persist for a very long time, depending on environmental conditions, but that they could also merge and merge.
They then tested the ability of these structures to sequester molecules from the environment and discovered that they accumulated large dye molecules to a remarkable degree. They then showed that these droplets could also harbor molecules of RNA and proteins while allowing them to function catalytically. In addition, the team has shown that the droplets could contribute to the formation of a lipid layer on their surface, suggesting that they could have contributed to the formation of a protocol.
Jia and his colleagues are not sure that these structures are the direct ancestors of the cells, but they think that it is possible that such droplets could have allowed the badembly of protocells on Earth. The new compartmentalization system they found is extremely simple, they note, and could easily be formed in the primitive environments of the Universe. "This allows us to imagine non-biological systems on the primitive Earth that could still play a role in the origins of life on Earth. This suggests that many other non-biological systems may need to be the focus of future investigations. this type. "He thinks that the development of these model systems or similar systems could allow a better study of the evolution of various chemical systems representative of complex chemistries likely to be encountered on primitive planetary bodies.
"The primitive Earth was certainly a chemically disordered place," Jia explains, "and most of the studies on the origins of life focus on modern biomolecules under relatively" clean "conditions – perhaps it is important to take these "disordered" mixtures to see if there are any interesting functions or structures that can arise from them spontaneously ". The authors now think that by systematically increasing the chemical complexity of such systems, they will be able to observe their evolution over time and possibly discover divergent and emerging properties.
"We now have this new experimental system, so we can begin to study phenomena such as the evolution and the evolution of these droplets, and the possible combinations of structures or functions of these droplets are almost infinite. If the physical rules governing droplet formation are of a fairly universal nature, we hope to study similar systems to determine if they can also form microdroplets with novel properties, "Jia adds.
Finally, although the team is currently focusing on understanding the origins of life, she notes that this basic research may have applications in other areas, such as drug delivery and personalized medicine. "It is only a wonderful example of unexpected means that projects can develop when a team of scientists from around the world comes together to try to understand new and interesting phenomena," he said. said Jim Cleaves, member of the team, also of ELSI.
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Reference:
Tony Z. Jia1.2 *Kuhan Chandru1,3,4 *, Yayoi Hongo1Rehana Afrin1, Tomohiro Usui1.5Kunihiro Myojo6and H. James Cleaves II1,2,7,8, Membrane-free polyester micro-droplets as primordial compartments at the origin of life, PNAS, DOI: 10.1073 / pnas.1902336116
1. Earth-Life Institute of Sciences, Tokyo Institute of Technology, Meguro-ku, 152-8550 Tokyo, Japan;
2. Blue Marble Institute of Space Sciences, Seattle, WA 98154;
3. Department of Physical Chemistry, University of Chemistry and Technology, Prague, 16628, Prague 6 – Dejvice, Czech Republic;
4. Space Science Center, Institute of Climate Change, National University of Malaysia, 43650 UKM Bangi, Selangor Darul Ehsan, Malaysia;
5. Institute of Space Science and Astronautics, Japan Aerospace Exploration Agency, Sagamihara, 252-5210 Kanagawa, Japan;
6. Department of Earth and Planet Sciences, Tokyo Institute of Technology, Meguro-ku, 152-8551 Tokyo, Japan;
7. Institute of Advanced Studies, Princeton, NJ 08540; and
8. Center for Chemical Evolution, Georgia Institute of Technology, Atlanta, GA 30332
Tokyo Institute of Technology (Tokyo Tech) is at the forefront of research and higher education as the leading university of science and technology in Japan. Tokyo Tech researchers excel in areas ranging from materials science to biology, computer science and physics. Founded in 1881, Tokyo Tech is home to more than 10,000 undergraduate and graduate students each year, who are among the most sought after scientists and engineers in the industry. Embodying the Japanese philosophy of "monotsukuri", which stands for "technical ingenuity and innovation", the Tokyo Tech community strives to contribute to society through high-impact research.
Institute of Earth and Life Sciences (ELSI) It is one of the ambitious research centers of World Premiere International in Japan, whose goal is to advance in broad interdisciplinary scientific fields by inspiring the greatest minds of the world to come to Japan and allowing them to collaborate on the most difficult scientific problems. The main goal of ELSI is to tackle the origin and co-evolution of the Earth and life.
The Global Initiative of International Research Centers (WPI) was launched in 2007 by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) to help create world-renowned research centers in Japan. These institutes promote high research standards and exceptional research environments that attract frontline researchers from around the world. These centers are highly autonomous, allowing them to revolutionize the traditional modes of operation and administration of research in Japan.
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