In mythologies and origin tales world wide, numerous cultures and religions level to clay because the vessel of life, the primordial materials that creator gods imbued with a self-sustaining existence. Nowadays we have now biology to clarify how life involves be, however might these tales of outdated hit nearer to the mark than we expect?
In a paper written to commemorate the work of Ned Seeman, inventor of the sector of DNA nanotechnology, UC Santa Barbara biophysicist emerita Helen Hansma outlines her longstanding concept that that primitive life, in pre-cellular preparations that developed into our lipid and protein-based cells, could have gotten its begin in micaceous clay. Her paper seems within the Biophysical Journal.
Originally proposed nearly 16 years in the past, Hansma’s speculation joins many different speculations about how life on Earth first took place. Among them are the well-known “RNA World,” through which self-replicating RNA molecules developed into DNA and proteins, and the “Metabolism First” idea, that claims life developed out of spontaneous chemical reactions. There’s additionally a “pizza” speculation that claims that life might have come from terrestrial natural biomolecules. And there are different clay hypotheses that say life could have originated on montmorillonite clay, or iron-rich clays.
Hansma did not set out to determine how life developed on Earth when she first stumbled on her concept. Rather, as a analysis biophysicist and a program director on the National Science Foundation again round 2007, she was taking part in together with her favourite toys—a dissecting microscope and mica items that she was splitting into sheets.
“As I looked at the bits of green algae and brown crud at the edges of the mica sheets, I thought, ‘this would be a good place for life to originate,'” she mentioned in an article written for NSF about her work.
Her concept incorporates parts of different ideas of abiogenesis (how life emerged from non-living materials), asserting that precursors to biomolecules and metabolic processes might all have been corralled between layers of mica. It’s an setting that provided some safety from the skin world, but allowed for the free change of water and different substances that might turn into important to cells.
“My image is that the surfaces of mica sheets were a great place for molecules to grow and processes to develop, and eventually everything needed for life was on the mica,” she mentioned. Essentially, the mica acted as scaffolding and “reaction chambers,” the place metabolic processes might happen and evolve. The benefit mica clays have over montmorillonite, Hansma added, is that micas, with potassium ions holding mica sheets collectively, are non-swelling and due to this fact present a extra secure setting. Montmorillonite sheets, in distinction, are held collectively by smaller sodium ions, leading to shrinking and swelling throughout wet-dry cycles and a much less secure setting.
The presence of potassium ions in micaceous clay is one other consider favor of the mica clay speculation: The cells in residing creatures have excessive intracellular concentrations of potassium, making mica “a more likely habitat for the origins of life than montmorillonite.”
And the place would this prebiotic assemblage get the vitality to work together and maintain itself within the absence of the biochemical vitality that now powers our our bodies? At that point, daylight would have been one candidate, Hansma suggests, as would have been mechanical vitality, by way of the opening and shutting of the mica sheets as water flowed out and in.
“It seems to be that these open-and-shut movements were ways of squishing molecules together, back before there was chemical energy,” she mentioned. This compelled proximity might have promoted interactions between the molecules, just like the actions of enzymes right now. Different interacting molecules would mix to kind RNA, DNA and proteins. Lipids within the combine would ultimately wrap across the teams of huge molecules and turn into the cell membrane.
These are however a couple of of the arguments in Hansma’s speculation that lend themselves to life having began in micaceous clay; different help will be present in mica’s outdated age, and within the mineral’s affinity for biomolecules and different elements which are thought to have promoted the event of life from non-living molecules.
While it is not going that we’ll ever know with certainty what occurred nearly 4 billion years in the past, it is clear that—as Hansma says—”Life imitates mica in many ways.”
Helen Greenwood Hansma, DNA and the origins of life in micaceous clay, Biophysical Journal (2022). DOI: 10.1016/j.bpj.2022.08.032
University of California – Santa Barbara
Did life get its begin in micaceous clay? (2022, September 20)
retrieved 20 September 2022
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