If you’ve survived Shiga toxin and the after-effects of food poisoning, you may have been the innocent victim of a battle for survival between predator and prey.
Bacteria that carry a virus (a bacteriophage) that packs the Shiga toxin gene (Stx) may depend on it for protection from bacterial predators like the ciliated protozoan Tetrahymena. This is small comfort if you’ve just consumed that Food poisoning victims -- as a result, for example, of consuming Shiga-packing E.coli in a contaminated bag of spinach -- have always had the cold comfort of being told that not all common bacteria make humans extremely sick, only the strains that have integrated the Shiga gene into their DNA. These bacteria can produce large amounts of the Shiga toxin and release it into the surrounding environment.
Leaving sick humans aside for a moment, Gerald Koudelka, Todd Hennessey, and colleagues from the University at Buffalo in Amherst, New York, wondered what evolutionary advantage the bacteria would derive from carrying around such a prickly viral hitchhiker. They hypothesized that the Stx gene might give the bacterial host an equalizer against bacterial predators.
“Humans may not be the major target of this toxin,” explains Koudelka. “Instead, they might be simply caught in the cross-fire in this ancient battle between prey and predators.”
To test their hypothesis, the researchers grew Tetrahymena with an E. coli strain (EDL933) that carries the Stx gene. It worked, at least, for the EDL933 that grew successfully in co-cultures with Tetrahymena. In this hostile environment, it was the predator, Tetrahymena, that was killed by the bacteria’s Shiga toxin. An E. coli strain (W3110) lacking Stx did poorly with Tetrahymena as roommates. The Tetrahymena had them for lunch.
The Shiga toxin kills by binding to a receptor on the surface of Tetrahymena. Adding protein subunits that block toxin binding to the protozoan predator prevented killing by Shiga toxin. Humans have the same surface receptor for Shiga toxin as do Tetrahymena, which gives biologists and produce packers a close interest in the deadly duel between Tetrahymena and Shiga-packing E. coli.
The Koudelka and Hennessey labs are continuing to characterize the route of Shiga toxin entry into the cytoplasm of Tetrahymena, its mode of killing, and the ability of Tetrahymena to develop resistance to Shiga toxin. The protozoan might make a model cellular system for Shiga detoxification, which one day might relieve some of the stress around the salad bar, say Koudelka and Hennessey.
John Fleischman | EurekAlert!
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences