SoylentNews is people
SoylentNews
Genes Hint that Life Originated in Hydrothermal Area
Science Magazine and the New York Times report on work published in Nature Microbiology (full article paywalled) (DOI: 10.1038/nmicrobiol.2016.116). Searching through databases, geneticists looked for genes shared among prokaryotes (bacteria and archaea). Their goal was to identify traits of the last universal common ancestor—an organism from which all cellular life is descended.
The genes that met their criteria suggest an organism that could incorporate nitrogen from molecular nitrogen and carbon from carbon dioxide into their cells—they were autotrophs rather than heterotrophs (they did not rely on other organisms as a source of carbon). Also suggested is that the organism was thermophilic, (thriving at high temperatures) and anaerobic (not using oxygen). The researchers think it had the Wood–Ljungdahl pathway, also known as the reductive acetyl-coenzyme A pathway, in which hydrogen is oxidised, carbon dioxide is reduced, organic molecules are synthesised, and chemical energy is made available to the organism.
They say that these characteristics support the idea that life originated in hydrothermal conditions. Such conditions exist today in hot springs, underground waters in volcanic areas, and deep-sea vents.
Meet Luca, the Ancestor of All Living Things
The New York Times published a story yesterday that demonstrates that with sweat and persistence, long lost relatives can be found:
A surprisingly specific genetic portrait of the ancestor of all living things has been generated by scientists who say that the likeness sheds considerable light on the mystery of how life first emerged on Earth.
This venerable ancestor was a single-cell, bacterium-like organism. But it has a grand name, or at least an acronym. It is known as Luca, the Last Universal Common Ancestor, and is estimated to have lived some four billion years ago, when Earth was a mere 560 million years old.
The new finding sharpens the debate between those who believe life began in some extreme environment, such as in deep sea vents or the flanks of volcanoes, and others who favor more normal settings, such as the "warm little pond" proposed by Darwin.
The article goes on to describe how this discovery was made, and concludes:
[The genetic analysis performed in the research] pointed quite precisely to an organism that lived in the conditions found in deep sea vents, the gassy, metal-laden, intensely hot plumes caused by seawater interacting with magma erupting through the ocean floor.
No doubt there is more to be revealed on this subject.
(Score: 1) by curril on Tuesday July 26 2016, @07:59PM
...modern DNA analysis has superglued it and then buried it under the Roosevelt Dam.
This is a bit too strong. Modern DNA analysis can't identify the LUCA, only code that has become common across all cell lines. Consider starting with cell A that later has a descendent B with a mutation that dominates across all cell lines. After the fact , there is no sure way to determine which DNA code was in A and which was new in B. Now consider another mutation C that happens fairly often and comes to dominate across all cell lines. There is no sure way with DNA analysis to determine if C was inherited from a common ancestor or occurred as a mutation across multiple cell lines.
Once you get back to the really messy bits of abiogenesis where gene replication was very imperfect and genes were created, lost, and recreated all of the time, the concept of a LUCA tends to lose meaning. After genes get complex enough that, to use your metaphor, reinventing the wheel is unlikely to occur, then ancestry becomes more well defined. So the LUCA becomes something of an arbitrary dividing point between cells with well-defined ancestors and organic, self-replicating soup.