Many intracellular (living in another cell) bacteria are serious vectors of disease. These include the bacteria that cause mite-borne typhus, which accounted for more deaths among soldiers in Southeast Asia during World War II than the fighting did. Diseases that correspond to this one in the Western world are epidemic typhus and trench fever, diseases that spread via the human louse and whose genome has already been charted by the Swedish research team.
These scientists have shown that the genome of the mite-borne typhus bacterium is 200 times more repetitive than that of its close relative, the louse-borne typhus bacterium. In total, nearly 40 percent of the two million bases consist of identical gene copies of proteins that govern the interaction between the bacterium and its host cell. Today most of these copies are in the process of being erased and probably fulfill no function.
“From the point of view of evolution, these findings are astonishing. Previous studies of bacteria from aphids and body lice have presented minimalist genomes with no gene copies. The genome of the mite-borne typhus bacterium, on the other hand, has more repeated material that any other bacteria that have been mapped so far," says Siv Andersson.
According to classical evolutionary theory, the fittest and best-adapted individual survives by beating out the weaker individuals. Studies of intracellular bacteria indicate that the process of selection can be short-circuited in small populations that go through repeated bottlenecks. This allows what would normally be rare and extreme variants to become dominant.
“The role of chance in the transmission of bacteria between mites and host animals may offer an explanation for our finding the most extreme genome in these particular bacteria. Another might be that the multiple copies for interaction with the host cell have played an important role in the evolutionary process," says Siv Andersson.
The Swedish research team has previously shown that intracellular bacteria can develop extremely small bacterial genomes without any repeated material. Now the bacterium that causes mite-borne typhus has set a new world record in the category “the world’s most repetitive bacterial genome."
Anneli Waara | alfa
Molecular evolution: How the building blocks of life may form in space
26.04.2018 | American Institute of Physics
Multifunctional bacterial microswimmer able to deliver cargo and destroy itself
26.04.2018 | Max-Planck-Institut für Intelligente Systeme
Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...
At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.
Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
26.04.2018 | Power and Electrical Engineering
26.04.2018 | Life Sciences
26.04.2018 | Power and Electrical Engineering