Scientists find out geological scenario that may have kickstarted life
A groundbreaking study, published in eLife, has revealed a plausible geological scenario that could have facilitated the replication of nucleic acids, the fundamental genetic building blocks of life. The research suggests that this process may have played a crucial role in the emergence of life on Earth. The study is based on the premise that gas flow over a narrow water channel, can create conditions conducive to nucleic acid replication.
The role of RNA in the origin of life
The origin of life on Earth remains a mystery, with one prevalent theory suggesting that the replication of genetic material—DNA and RNA—was a central process. RNA molecules are capable of storing genetic information and catalyzing their own replication, by forming double-stranded helices. This unique ability allows them to mutate, evolve, and adapt to various environments, ultimately encoding the protein building blocks necessary for life.
Challenges in RNA replication process
For RNA to replicate, it must not only form a double-stranded helix but also separate again to complete the replication cycle. This separation is challenging due to the high salt and nucleic acid concentrations required for replication. "Various mechanisms have been studied for their potential to separate DNA strands at the origin of life, but they all require temperature changes that would lead to degradation of nucleic acids," says lead author Philipp Schwintek from Ludwig-Maximilians-Universitat Munchen.
Geological scenario for RNA synthesis explored
The research team explored a geological scenario, where water movement through a rock pore was dried by gas percolating through the rock to reach the surface. This setting would be common on early Earth's volcanic islands, providing the necessary dry conditions for RNA synthesis. The team constructed a laboratory model of this scenario and used beads to monitor water flow dynamics, tracking the movement of fluorescently labeled short DNA fragments.
Accumulation of DNA strands at the interface
The team found that continuous evaporation led to a significant accumulation of DNA strands at the gas/water interface. Within five minutes, there was a three-fold increase in DNA strands, and after an hour, this number had increased to 30 times more. This suggests that the gas/water interface could allow for a sufficient concentration of nucleic acids for replication to occur.
Separation of DNA strands in constant temperature
Separation of the double DNA strands is also necessary for replication. Usually, a change in temperature is necessary, but when the temperature is constant, changes in salt concentration are required. "We hypothesized that the circular fluid flow at the interface provided by the gas flux, alongside passive diffusion, would drive strand separation by forcing nucleic acids through areas with different salt concentrations," explained senior author Dieter Braun of Ludwig-Maximilians-Universitat Munchen.
Testing the hypothesis of DNA strand separation
To test their hypothesis, the researchers used a method called FRET spectroscopy to measure DNA strand separation. The results aligned with their expectations, showing an initial increase in the FRET signal near the gas-water interface, indicating double-stranded DNA formation. However, over time where there was an upward flow of water, the FRET signal was low—indicating single-strand DNA.
