The findings open a new window on microbial evolution, demonstrating for the first time that geography can trump other factors that influence the makeup of genes an organism hosts.
S. islandicus belongs to the archaea, a group of single-celled organisms that live in a variety of habitats including some of the most forbidding environments on the planet. Once lumped together with bacteria, archaea are now classified as a separate domain of life.
“Archaea are really different from bacteria – as different from bacteria as we are,” said University of Illinois microbiology professor Rachel Whitaker, who led the study.
The extreme physical needs of S. islandicus make it an ideal organism for studying the impact of geographic isolation. It can live only at temperatures that approach the boiling point of water and in an environment that has the pH of battery acid. It breathes oxygen, eats volcanic gases and expels sulfuric acid. It is unlikely that it can survive even a short distance from the hot springs where it is found.
By comparing the genetic characteristics of individuals from each of the three locations, Whitaker and her colleagues were able to see how each of the S. islandicus populations had evolved since they were isolated from one another more than 900,000 years ago.
The complete genetic package, or genome, of S. islandicus contains a set of core genes that are shared among all members of this group, with some minor differences in the sequence of nucleotides that spell out individual genes. But it also contains a variable genome, with groups of genes that differ – sometimes dramatically – from one subset, or strain, to another.Whitaker’s team found that the variable genome in individual strains of
“Some people think that these variable genes are the way that microbes are adapting to new environments,” Whitaker said. “You land in a new place, you need a new function in that new place, you pick up that set of genes from whoever’s there or we don’t know who from, and now you can survive there. We have shown that does not occur.”
“This tells you that there’s a lot more diversity than we thought,” Whitaker said. “Each hot spring region has its own genome and its own genome components and is evolving in its own unique way. And if each place is evolving in its own unique way, then each one is different and there’s this amazing diversity. I mean, beetles are nothing compared to the diversity of microbes.”
Archaea, like bacteria, can transfer genes to one another, but they also obtain new genes from free-floating genetic elements, called plasmids, or from viruses that infect the cells and insert their own genes into the archaeal DNA. What did vary in the genomes of S. islandicus could be traced back to plasmids and viruses, Whitaker said. There were also a lot of lost genes, with much variation in the genes lost between the strains.
“Most of the genes that are coming and going, at least on Sulfolobus, seem to be on viruses and plasmids,” Whitaker said. The researchers found that about one-third of the variable genes were specific to a geographic location. The viruses and plasmids that had lent their genes to Sulfolobus in one site were different from those found in another. Also, much of the variation was found in genes devoted to the microbe’s immune system, indicating that S. islandicus is evolving largely in response to the assault of local pathogens such as viruses.
These findings challenge the idea that microbes draw whatever they may need from a near-universal pool of available genetic material, Whitaker said. It appears instead that S. islandicus, at least, acquires new genes from a very limited genetic reservoir stored in viruses and other genetic elements that are constrained to each geographic location on Earth.
Diana Yates | Newswise Science News
Münster University researchers develop new synthesis method for producing fluorinated piperidines
22.01.2019 | Westfälische Wilhelms-Universität Münster
New blood vessel system discovered in bones
22.01.2019 | Universität Duisburg-Essen
Immune cells called macrophages are supposed to serve and protect, but cancer has found ways to put them to sleep. Now researchers at the Abramson Cancer...
The scientific and political community alike stress the importance of German Antarctic research
Joint Press Release from the BMBF and AWI
The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...
World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles
The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
22.01.2019 | Materials Sciences
22.01.2019 | Health and Medicine
22.01.2019 | Health and Medicine