How could terrestrial living organisms withstand the hostile environments of other planets? To answer this question, a research team chose to examine yeast, a common microorganism, under Martian conditions. Their work sheds light on an unexpected cellular tactic that could prove crucial for the persistence of life.
The Martian surface is exposed to shock waves and its soil contains perchlorates, chemically aggressive salts that can damage molecular structures of living matter. This combination of factors contributes to shaping an environment that is particularly challenging for any organism.
To study the mechanisms at play, scientists used the yeast Saccharomyces cerevisiae, known as "baker's yeast," frequently used as a model organism in biology. They replicated in the laboratory stresses analogous to those on Mars, by applying shock waves and exposing the cells to perchlorates. This method allows for real-time observation of cellular reactions.
Faced with these aggressions, the yeast assembles structures called ribonucleoprotein condensates. These aggregates of RNA and proteins function to preserve RNA molecules and control their use. Their formation is rapid in the face of danger, and they disperse as soon as conditions return to normal.
Formation of ribonucleoprotein condensates in response to stress conditions similar to those on Mars.
Credit: Dhage et al. The experiments demonstrated that yeast survives both shock waves and perchlorates, even though its growth is hindered. Conversely, mutants incapable of producing these condensates show reduced resistance. This finding indicates that these structures are directly involved in the ability to withstand extreme conditions.
The examination of genes activated under Martian stress revealed specific changes in RNA expression. The authors of the study, published in
PNAS Nexus, indicate that these observations help to better understand how life might adjust on other planets.