November 8, 2013
Clay May Have Been The Long-Sought Cradle Of Life
[ Watch the Video: Life On Earth May Have Come From Clay ]
Brett Smith for redOrbit.com - Your Universe Online
Often viewed as an apparently infertile blend of various minerals, clay might have actually been the birthplace of life on Earth, biological engineers from Cornell University report in new research appearing in Thursday’s online edition of the journal Scientific Reports.
The study authors set out to simulate ancient seawater in order to analyze the properties of clay under those conditions. They found that in such an environment, clay can form a substance known as a hydrogel – a mass of microscopic pores capable of absorbing liquids like a sponge.
Over the course of several billion years, chemicals confined in those spaces could have undergone the complex reactions that led to the formation of protein, DNA and other essential components of living cells. Those clay hydrogels might have entrapped and protected those processes until a cell membrane was able to develop.
Dan Luo, a professor of biological and environmental engineering at Cornell University, and colleagues demonstrated protein synthesis in a clay hydrogel in order to test their theory. Previously, they had used synthetic versions of these sponge-like substances as a 'cell-free' vessel for protein production. By filling the hydrogel with DNA, amino acids, enzymes and other cellular components, they found that it is possible to make the proteins for which genetic material encodes.
Of course, in order to use this process to create proteins en masse for pharmaceutical manufacturing or other purposes, a lot of hydrogel is required. So Luo’s team set out to find a less expensive way to manufacture it. Not only did they found that clay could form a hydrogel, they unexpectedly found that using the mineral-rich substance actually enhanced the protein production process.
“Carl Sagan, a now-deceased experimental researcher from Cornell, produced evidence substantiating the notion that a number of biomolecules were first formed within primordial oceans, channeling energy from volcanic vents and lightning,” Fenner said. “However, the mystery over the exact mechanisms that were involved in driving these complex biochemical processes remains somewhat elusive.”
“Researchers have desperately tried to fathom how these molecules could coalesce and assemble to generate more complex structures, whilst remaining protected from the environment,” he added. “Some scientists have alleged that polymers, or small bubbles of fatty materials, could have served as preliminary iterations of cell membranes. Clay hydrogel is a likely candidate for such a structure, since biomolecules are able to affix to their surfaces.”
The discovery that cytoplasm behaves like a hydrogel substance, and is capable of protecting DNA from the catalytic activities of nuclease enzymes, lends credence to this idea as well. Furthermore, historical record shows that clay first appeared at the same time that biomolecules began form into the incomplete, cell-like structures known as protocells.
Luo and colleagues from the Australian Institute for Bioengineering and Nanotechnology at the University of Queensland are currently uncertain exactly how those biological mechanisms evolved. Their focus at this time is to discern why clay hydrogel is so effective, and how this process could be used in practical cell-free protein production applications.