"Ancient thermometer" reveals primordial Earth's temperature

Washington, Feb 8 : A team of scientists has reconstructed proteins from ancient bacteria to measure the Earth's temperature over the ages.

Using this genetic equivalent of an ancient thermometer, scientists from the University of Florida and the Foundation for Applied Molecular Evolution and the biotechnology company DNA2.0, have determined that the Earth endured a massive cooling period between 500 million and 3.5 billion years ago.

"By studying proteins encoded by these primordial genes, we are able to infer information about the environmental conditions of the early Earth," said Eric Gaucher, Ph.D., president of scientific research at the Foundation for Applied Molecular Evolution in Gainesville and the study's lead scientist.

According to Gaucher, "Genes evolve to adapt to the environmental conditions in which an organism lives. Resurrecting these since long-extinct genes gives us the opportunity to analyze and dissect the ancient surroundings that have been recorded in the gene sequence."

"The genes essentially behave as dynamic fossils," he explained.

The research team wanted to measure Earth's temperature billions of years ago to learn more about life on Earth during the Precambrian period.

But instead of taking the traditional route - analyzing rock formations or measuring isotopes in fossils - they opted to reconstruct the protein from ancient bacteria.

"We've analyzed the temperature stability of proteins inside organisms that were around during those times," said Omjoy Ganesh, Ph.D., a structural biologist in the UF College of Medicine's department of biochemistry and molecular biology.

"The ancient oceans were warmer. For ocean organisms living during that time to survive, the proteins within them had to be stable at high temperatures," he explained.

After scanning multiple databases, the scientists found success with a protein called elongation factor, which helps bacteria string together amino acids to form other proteins.

Armed with information about when bacterial species evolved, the scientists rebuilt 31 elongation factors from 16 ancient species. By comparing the heat sensitivity of the reconstructed proteins, they were able to discern how Earth's temperature changed over the ages.

According to the scientists, almost all bacteria are related if you go back far enough. Even organisms that like extreme heat are related to organisms that are very sensitive to temperature change.

The key is determining when, during Earth's history, each type of bacteria came into existence.

"Remarkably, our results are nearly identical to geologic studies that stimate the temperature trend for the ancient ocean over the same time period," said Gaucher.

"The convergence of results from biology and geology show that Earth's environment has continuously been changing since life began, and life has adapted appropriately to survive," he added.

ANI