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Science

Scientists Discover New Chemistry That May Help Explain Origins of Cellular Life (phys.org) 83

An anonymous reader quotes a report from Phys.Org: Before life began on Earth, the environment likely contained a massive number of chemicals that reacted with each other more or less randomly, and it is unclear how the complexity of cells could have emerged from such chemical chaos. Now, a team led by Tony Z. Jia at the Tokyo Institute of Technology and Kuhan Chandru of the National University of Malaysia has shown that simple a-hydroxy acids, like glycolic and lactic acid, spontaneously polymerize and self-assemble into polyester microdroplets when dried at moderate temperatures followed by rehydration. This could be what happened along primitive beaches and river banks, or in drying puddles. These form a new type of cell-like compartment that can trap and concentrate biomolecules like nucleic acids and proteins. These droplets, unlike most modern cells, are able to merge and reform easily, and thus could have hosted versatile early genetic and metabolic systems potentially critical for the origins of life.

Previous work conducted at ELSI showed that moderate temperature drying of the simple organic compounds known as alpha-hydroxy acids, which are found in meteorites and many simulations of prebiological chemistry, spontaneously polymerizes them into mixtures of long polyesters. Building on this work, Jia and colleagues took the next step and examined these reactions under the microscope, and found that these mixed polyester systems form a gel phase and spontaneously self-assemble when rewetted to form simple cell-like structures. [...] Jia and colleagues are not certain these structures are the direct ancestors of cells, but they think it is possible such droplets could have enabled the assembly of protocells on Earth. The new compartmentalization system they have found is extremely simple, they note, and could form easily in primitive environments throughout the universe.
"We have this new experimental system we can now play with, so we can start to study phenomena like evolution and evolvability of these droplets. The possible combinations of structures or functions these droplets might have are almost endless. If the physical rules that govern the formation of droplets are fairly universal in nature, then we hope to study similar systems to discover whether they also can form microdroplets with novel properties," adds Jia.

The study has been published in the journal PNAS.
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Scientists Discover New Chemistry That May Help Explain Origins of Cellular Life

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  • by Brett Buck ( 811747 ) on Friday July 26, 2019 @01:29AM (#58989110)

    moderate temperature drying of the simple organic compounds known as alpha-hydroxy acids, which are found in meteorites and many simulations of prebiological chemistry, spontaneously polymerizes them into mixtures of long polyesters.

            I don't know about the origin of life, but it does explain the origin of my powder blue leisure suit.

  • by SpaceCracker ( 939922 ) on Friday July 26, 2019 @02:38AM (#58989290)

    Spontaneous compartments are still not cellular life. A self-replicating molecule is almost there. A self-replicating molecule that can also produce other molecules that assemble as a protective membrane is even closer. I'm guessing that before the membrane producing "gene" there was some other "gene" that encoded an energy harvesting mechanism that could be used for activities such as replication.

  • by mentil ( 1748130 ) on Friday July 26, 2019 @03:15AM (#58989394)

    Life evolved from polyester?! Barbarella was right!

  • by aberglas ( 991072 ) on Friday July 26, 2019 @03:16AM (#58989396)

    Is it something that happens in any chemical environment like the early Earth given a few million years? Or is a complete fluke that would only happen on one in a billion Earth-like planets? That is the big question.

    Various simulations of supposed early Earth-like chemicals have been done, and an early one added lightning which produced lots of organics. But you have to produce some complex molecule, consisting of a series of bases, that replicates itself without having complex machinery already in place. That is needed before evolution can begin.

    Whether this paper adds much to the mystery is difficult to tell.

    • Re: (Score:3, Informative)

      by Anonymous Coward
    • by mentil ( 1748130 ) on Friday July 26, 2019 @08:27AM (#58990112)

      Technically, all you need are the ability to replicate and mutate, in order to end up where we are. I recall reading (here? can't find it) that amino acids quickly self-assemble into proteins, presumably in a somewhat-random fashion. It was recently found that life arose on Earth very quickly once it'd cooled enough for life to not be destroyed right away.

      (I speculate that) naked proteins assemble randomly, and one assembles that is able to attach complementary amino acids to itself to create a 'mirror' of itself, and shed the mirror, which is itself able to create mirror copies of itself. Mutation eventually leads one of these proteins to be able to build other proteins according to how itself is composed; proteins that retain the ability to replicate, yet happen to contain information that is used to build a protein which then increases the likelihood of replication, tend to proliferate, and that's the beginnings of natural selection. Organelles and cell walls came after mutation/replication/encoding came into being.

      • I think one thing that we all lose sight of is how absolutely mindbogglingly vast geologic time is. A common activity in school is to map geologic time to a calendar.

        Earth cools on Jan 1, oldest rocks form in mid-March, primitive life doesn't show up until November, the dinosaurs show up around the second week of December and are gone by the end of the third, and humans show up on the evening of December 31st. Everyone alive now shows up the last millisecond of the year.

        Our entire humanoid existence can be

        • Using your "year" scaling, the oldest generally accepted life was in March or April, but there is disputed evidence for life before that in early or mid- March (stable isotope ratios in graphites in Greenland gneisses). May and part of June was spent with massive chemical pollution from the first oxygenic photosynthetic organisms (non-oxygenic photosynthetic organisms probably pre-dated them) leading to oceans almost devoid of iron, and free oxygen in the atmosphere. Life forms with hard skeletons evolved a
    • If life was found to be existing on Mars that would settle the question. It would be the most important discovery we have ever made (next to the Jonas Brothers)

      • But if no evidence of life was found on Mars, that would not alter the odds of finding life on Europa.

        Mars is sufficiently Earth-like (and was, particularly back in the Hesperonian and Noachian periods) that finding evidence of life there wouldn't greatly alter our knowledge of the range(s) of conditions under which life can start.

  • The last sentence: "If the physical rules that govern the formation of droplets are fairly universal in nature, then we hope to study similar systems to discover whether they also can form microdroplets with novel properties," adds Jia." is of particular interest to me. I'm curious about what conditions must be present to create these polyester drops and what happens in other conditions. Temperature, atmospheric pressure, surface tension, etc. all might play a role. If other conditions are present, does
  • Cells forming is not that hard. Specifically, forming globules of a thin membranes from fatty acids with a hydrophobic side and hydrophilic side is mostly a spontaneous thing that does not need any external factor. It has been demonstrated to happen in the labs.

    What is harder is metabolism, having pores in the above membranes to ferry molecules in and out, and then the chemistry needed to extract energy from a proton gradient, storing it (e.g. sugars), and using it (e.g. in the ATP form).

    The hardest part is

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