The study reveals that germ-free mice are more susceptible to infection with the foodborne pathogen Listeria monocytogenes than mice with conventional intestinal microbiota.
The authors were also able to show that expression of five intestinal microRNA (miRNA) molecules decreases in conventional mice upon Listeria infection while it did not in germ-free mice, indicating that the gut microbiota may determine, at least in part, how the mouse genome expression is reprogrammed in the gut and how the animal responds to an infection.
"We were surprised by the robustness of the intestinal miRNA signature in germ-free mice and conventional mice," says corresponding author Pascale Cossart of the Institut Pasteur in Paris, France. "Our results show that even very small variations in miRNA expression can have important outcomes," for the health of the animals, says Cossart.
In recent years, researchers have come to recognize that the gut microbiota is an indispensable partner in the development of an animal's immune response and in maintaining its internal stability, but few studies have addressed the impact the microbiota has on miRNA expression during bacterial infections. Cossart and her colleagues approached the matter using the system they know best: Listeria infection. L. monocytogenes is a frequent contaminant of raw milk products, and a highly publicized outbreak traced to Listeria-contaminated cantaloupe left 30 people dead in the fall of 2011.
Previous studies in Cossart's lab have shown that during infection with Listeria, the bacterium AND the host both reprogram their protein manufacturing using small non-coding RNA molecules like miRNA - pieces of genetic material that are used to selectively regulate the creation of proteins. Here, the researchers used conventional mice and germ-free mice to address the question of whether - and how - the gut microbiota has an effect on the course of infection and on the production of these regulatory miRNA molecules.
When it comes to susceptibility to infection, the results were unequivocal: 24 hours after infection, germ-free mice harbored 10,000 times more L. monocytogenes bacteria in their small intestines and about 1,000 times more Listeria in their mesenteric lymph nodes than did the conventional mice.
At the level of miRNA, however, the differences were not immediately evident: the most highly expressed miRNAs were produced at the same levels in both types of mice and they didn't change much after infection. Nevertheless, the production of five miRNAs decreased after infection only in the conventional mice, indicating that the presence of the microbiota influences the level of miRNA expression.
"We found that even though the intestinal miRNA signature is globally stable, Listeria infection can affect the host miRNA response in a microbiota-dependent manner," says Cossart. When paralleled with the lower susceptibility of the conventional mice to infection, these down-regulated regulatory molecules present an intriguing result, write the authors.
Cossart says that this study and others indicate that miRNA may be involved in protecting the host from infection, but their precise role isn't yet clear. She notes that although this study was conducted in mice, miRNA and the protein coding gene targets they regulate may be very similar in mice and in humans. Cossart and her colleagues are planning to follow up on the work to try and figure out what impacts the changes in miRNA expression mean for the networks of protein-coding genes they regulate.
mBio® is an open access online journal published by the American Society for Microbiology to make microbiology research broadly accessible. The focus of the journal is on rapid publication of cutting-edge research spanning the entire spectrum of microbiology and related fields. It can be found online at http://mbio.asm.org.
The American Society for Microbiology is the largest single life science society, composed of over 39,000 scientists and health professionals. ASM's mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
Colorectal cancer risk factors decrypted
16.07.2018 | Max-Planck-Institut für Stoffwechselforschung
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Transportation and Logistics
16.07.2018 | Agricultural and Forestry Science