In the Beginning
Boron, a semimetallic chemical element, may be most commonly known for its various inorganic compounds such as the antiseptic boric acid, the cleaning agent borax and tourmaline, Maine’s state mineral.
But scientists have discovered this element may have had more of an effect on life on Earth than forming semiprecious gemstones and aiding with household chores. Boron has been credited with playing a crucial role in the formation of life on Earth.
Researchers have found that when boron is present in its oxidized form, or borate, it can stabilize ribose, a sugar present in the backbone of ribonucleic acid, or RNA, which plays a vital role in the expression of genes.
Scientists have suggested that borate present in the Earth’s crust or its oceans about half a billion years after the Earth was formed helped keep ribose from decomposing, allowing it to form RNA, which led to the stabilization of prebiotic organic compounds critical to forming life.
The possibility that boron could play a critical role in the origin of life is at the core of the latest research on boron isotopes by Edward Grew, a research professor in the University of Maine School of Earth and Climate Sciences.
Although working with boron is a familiar topic for Grew, who began collecting minerals in grade school and started focusing on boron and beryllium 30 years ago, the study of how minerals relate to the creation of life is an area he has only recently started to examine.
Grew is a member of a five-person team analyzing the world’s oldest reported tourmaline for the two isotopes of boron to determine the boron-isotope composition of the ocean not long after the critical period when life was forming, he says. Leading the team is Robert Hazen, senior staff scientist in the Geophysical Laboratory at the Carnegie Institution for Science, which is known legally as the Carnegie Institution of Washington.
The goal of the study, funded by a $15,000 grant from the Carnegie Institution for Science, is to estimate what boron concentrations were 4 billion years ago.
“There have been several scientists that have tried to deduce how you can get organic compounds to self-organize and ultimately evolve and become life,” Grew says. “One of the agents that would promote that is boron.”
Grew, along with researchers at institutions in the U.S. and Scotland, will analyze tourmaline that is up to 3.8 billion years old, found in the Isua complex in West Greenland. The tourmaline was contributed to the project by Robert Dymek, a professor in the Department of Earth and Planetary Sciences at Washington University in St. Louis.
Starting in July, the team will use microprobe techniques at the University of Maine, under the direction of laboratory manager and instructor Martin Yates, and at the University of Edinburgh in Scotland, overseen by Simon Harley, professor in the School of GeoSciences.
The electron microprobe data are needed to properly calibrate the isotope analyses, allowing the researchers to work backward using a model developed by French geochemists relating seawater boron isotope composition to the proportion of boron extracted from the Earth’s mantle to determine the isotopic composition of the ocean water at the same time the tourmaline was formed, according to Grew.
“Whether you had enough boron at that time for these scenarios to be possible is still quite an open question,” Grew says. “This idea that boron played a critical role [in the formation of life], I can’t really answer because I’m not an organic chemist. But the question of whether there was enough boron around, that’s the question we’re trying to answer.”
Since 2008, Hazen and Grew have been collaborating on mineral evolution research — in particular, whether there could have been boron-rich minerals at the time organic compounds were forming.
“Mineral evolution has a lot of parallels with biological evolution as we understand it,” Grew says. “Basically you think of minerals as though they’ve always been here, you don’t think of them in terms of time. So what mineral evolution does is introduce the idea of time as well as physical and chemical properties into the study of minerals.”
Grew began researching the topic and published the article “Borate minerals and origin of the RNA world” in the journal Origins of Life and Evolution of Biospheres in January 2011, setting the groundwork for the current project.
A recent study conducted by researchers at the University of Hawaii at Manoa NASA Astrobiology Institute, or UHNAI, also found relatively high concentrations of boron in a meteorite from Mars, according to a study in the journal PLOS ONE reported in a ScienceDaily article.
“Unexpected large amounts of boron in this Martian meteorite suggests that on Mars — at about the same time as West Greenland — there may have been enough boron to also go through this process of stabilizing prebiotic organic compounds,” Grew says.
He adds the Mars findings could add valuable perspective to his current research. Plate tectonics has played a major role in transferring boron to the crust from the mantle over much of Earth’s history, but it is still controversial whether there were plate tectonics either on Mars or on the early Earth.
Contact: Elyse Kahl, 581.3747