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
Gene therapy shows promise for treating Niemann-Pick disease type C1
27.10.2016 | NIH/National Human Genome Research Institute
'Neighbor maps' reveal the genome's 3-D shape
27.10.2016 | International School of Advanced Studies (SISSA)
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
27.10.2016 | Life Sciences
27.10.2016 | Life Sciences
27.10.2016 | Power and Electrical Engineering