The bottom of the sea may seem like an unlikely place for life to begin, but the hydrothermal vents that spew water and gases heated by the Earth’s core may have provided the right conditions for the formation of DNA molecules.
“In these environments, there’s the energy and raw materials that are needed to make the precursors to DNA molecules,” says Alex Lowe, a master’s student in the Department of Chemistry. These molecules, called nucleic acid bases, are among the building blocks of DNA and RNA.
“I measure their molecular volume and their heat capacity, basically their size and their ability to absorb heat energy,” says Lowe. “These are the data needed for models to determine under what favorable conditions they will form from their raw components,” such as cyanide and formaldehyde. Other molecules like amino acids and lipids are also thought to form under these conditions.
According to the hydrothermal vent theory, the high temperature and high pressure found in these vents provide molecules with the energy they need to form larger molecules. “The reason we’re looking at hydrothermal vents is that they act as natural chemical reactors,” says Lowe. “They’re porous enough that the raw materials can concentrate in these little pockets, like mini test tubes, and form the smaller precursor molecules that self-assemble into RNA in water.”
Lowe uses a high-temperature densitometer to measure molecular volumes under high pressure at 350°C. Although molecules can join together under these high temperatures, they can also fall apart. Lowe is trying to find the conditions at which they remain stable. He studies these molecules in the hydrothermal chemistry research lab, which is specially equipped with high precision instruments to mimic the conditions found on the ocean floor.
Astrobiologists could use the findings to compare the conditions on the sea floor with those found on other planets to see if they could support life. “If we know the conditions for the precursor molecules of life to form, then we can take a look at other planets,” says Lowe. He adds that Europa, an ice-covered moon of Jupiter, has geysers on its surface that indicate a similar hydrothermal environment may exist under the ice. If it does exist, could it produce molecules like those Lowe studies and possibly support simple organisms?