When it comes to origins of life (Ool) hypotheses, we are often served with beautiful stories on how one event follows another and then you get life. But, the devil is always in the details and we want it to be out, to be known and to be addressed.
“Only when negative results are permitted and theories can be abandoned will science progress in this area (OoL)”
-Robert Shapiro (1935 – 2011)
Here is a summary of my recent paper addressing a weakness in the metabolism first hypotheses in hydrothermal vents.
Thioesters, the prebiotic analogues of Acetyl coenzyme A is a linchpin organic compound in respiration processes in life. Its occurrences have been transposed into geochemical settings such as hydrothermal vents to form many metabolism first schemes for origins of life in the last 40 years or so. One glaring problem, despite the usual poised narration, is that, this hypothesis have survived so long without through investigations for that many years. Now, researchers at Earth-Life Science Institute (ELSI), an institute incepted to exclusively study the origins problem is doing just that, to set constrains on current OoL models and to produce more experimentally driven principles to understand the origins of life.
The open-source paper available in Sci.report, has demonstrated that the accumulated concentration of thioesters in HT vents are too insignificant to launch any meaningful progression in metabolism first schemes. Additionally, thioester (like Acetyl-Co-A) has a very limited shelf life; the researchers measured the decay rate and concluded that, depending on thioesters speciation and physical conditions, they are unlikely to persist in hydrothermal vent conditions for long, thus constraining the metabolism first hypotheses.
p.s: We are extremely delighted to get this piece out in an open source journal.
Figure is showing the possible formation of thioacetic acids, in blue and thioesters (methyl thioacetic acid) , in pink in hydrothermal vent systems.
Authors: Kuhan Chandru, Alexis Gilbert, Christopher Butch, Masashi Aono and Henderson James Cleaves II
Title: The Abiotic Chemistry of Thiolated Acetate Derivatives and the Origins of Life
Journal: Scientific Reports, 2016
One thought on “Setting constraints on origins of life’ hypotheses. Example 1: thioester world and metabolism first in hydrothermal vents”
It is interesting to read this after reading Martin et al’s recently phylogenetically derived LUCA, which has solely the Wood-Ljungdahl/acetyl-CoA metabolic pathway. But it has some geologically related unusual reactions due to an unexpected reliance on reactive C1 species, I take it.[ “he physiology and habitat of the last universalcommon ancestor”, Nature Microbiology, http://www.nature.com/articles/nmicrobiol2016116 ]
Both the genetic and the metabolic system of the UCA lineage, at least back to early RNA/protein cells, shows the geological signature of a vent environment in a phylogenetic analysis. (Moreover Martin et al stick out their chin and claim “half alive” geological dependence even at the LUCA stage.) This must put tension on biochemical theories for emergence of life.
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