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!
Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute
Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy