When a pathogen like Salmonella enterica infects a cell, the cell activates a series of signals, culminating in certain genes being turned on to activate protective immune responses. One group of proteins that turn on immune-related genes is known as the NF-kappaB transcription factors. Salmonella, however, produces its own set of proteins that stop this from happening.

“These (bacterial proteins) function as a molecular pair of scissors, cutting up NF-kappaB transcription factors and thereby sabotaging the infected cells’ immune response,” said Teresa Thurston, the investigator at Imperial who oversaw the work.

These sabotage proteins, collectively called zinc metalloprotease effector proteins, act surprisingly delicately for saboteurs. In the human cells that Salmonella enterica infects, there are five different types of NF-kappaB proteins, but the Salmonella effectors cut up only three of them, leaving the other two untouched.

“The interaction between the host and the pathogen is very complex,” Thurston said. “So what I think this selectivity means is that (the bacterial proteins) are able to affect a particular arm of the immune response while keeping other arms untouched. And, in that way, they’re really fine-tuning the host immune response rather than having a blanket bomb-out effect.”

Thurston’s team, led by graduate student Elliott Jennings, wanted to understand how these bacterial proteins were able to behave so accurately on a molecular level. To do so, the team produced a detailed 3-D structure of one of them, both alone and in complex with a human NF-kappaB protein.

They found a sophisticated mechanism of molecular sabotage. The NF-kappaB transcription factors do their job of turning on immune system genes by binding to DNA at specific locations. The Salmonella effector proteins take on the approximate shape and electrical charge of the DNA backbone, essentially tricking NF-kappaB proteins to stick to them instead; once this happens, the Salmonella protein cuts up the NF-kappaB protein.

The precision with which this occurs — targeting only three out of five NF-kappaB proteins — is strongly determined by the way the bacterial effectors interact with a single amino acid in the targeted NF-kappaB proteins.

“With a single change in the amino acid sequence, we could create a target that could no longer be cut,” Thurston said. “Also vice versa: After changing just one amino acid, (the effector) was then able to cleave a protein that was not normally targeted.”

In other words, the bacterial proteins distinguish between the human proteins based on just one specific amino acid.

Together, these findings contribute to a complex picture of how Salmonella runs roughshod over its human host by carefully breaking key molecules in immune signaling pathways.

“Maybe once we have a complete picture of how bacteria get one over their hosts, we can shift the balance in favor of the host,” Thurston said. “In the case of Salmonella infection, this could be important, as many of the fatalities are associated with immune-compromised patients.”

This is not fake news. A team of UCF astrophysicists has developed a scientifically based, standardized method for creating Martian and asteroid soil known as simulants.

The team published its findings this month in the journal Icarus.

“The simulant is useful for research as we look to go to Mars,” said Physics Professor Dan Britt, a member of UCF’s Planetary Sciences Group. “If we are going to go, we’ll need food, water and other essentials. As we are developing solutions, we need a way to test how these ideas will fare.”

For example, scientists looking for ways to grow food on Mars — cue the Martian movie — need to test their techniques on soil that most closely resembles the stuff on Mars.

“You wouldn’t want to discover that your method didn’t work when we are actually there,” Britt said. “What would you do then? It takes years to get there.”

UCF’s formula is based on the chemical signature of the soils on Mars collected by the Curiosity rover. Britt built two calibration targets that were part of Curiosity rover. Researchers currently use simulants that aren’t standardized, so any experiment can’t be compared to another in an apples-to-apples kind of way, Britt said.

As a geologist and a physicist, he knows his dirt. Like a recipe, the ingredients can be mixed in different ways to mimic soil from various objects, including asteroids and planets. And because the formula is based on scientific methods and is published for all to use, even those not ordering through UCF can create dirt that can be used for experiments, which reduces the uncertainty level.

Kevin Cannon, the paper’s lead author and a post-doctoral researcher who works with Britt at UCF, says there are different types of soil on Mars and on asteroids. On Earth, for example, we have black sand, white sand, clay and topsoil to name a few. On other worlds, you might find carbon-rich soils, clay-rich soils and salt-rich soils, he added.

“With this technique, we can produce many variations,” Cannon said. “Most of the minerals we need are found on Earth although some are very difficult to obtain.”

Cannon is in Montana to collect ingredients for a moon simulant this week. Moon and asteroid materials are rare and expensive on Earth since they arrived via meteorites in small amounts. That’s why asteroid and moon simulants are also on the list of items that can be ordered. The UCF team can mimic most ingredients and will substitute for any potentially harmful materials. All simulants produced in the lab, meet NASA’s safety standards.

Britt and Cannon believe there is a market for the simulant. At $20 a kilogram, plus shipping, it may be easier to send UCF an order, than to try and make it in labs across the nation.

The team already has about 30 pending orders, including one from Kennedy Space Center for half a ton.

“I expect we will see significant learning happening from access to this material,” Britt said.

Cannon believes it will help accelerate the drive to explore our solar system as demonstrated by investments already being made by Space X, Blue Origin and other private companies.

For Cody Schultz, a mechanical engineering senior, getting to work on the experimental soil has been “very cool.”

“For someone who has always loved space science, this is the ultimate cool,” he said. “And the experience is fantastic in terms of the real world … out-of-this-world experience.”

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Materials provided by University of Central Florida. Original written by Zenaida Gonzalez Kotala. Note: Content may be edited for style and length.

Little was known about a key element in the building blocks, phosphates, until now. University of Hawaii at Manoa researchers, in collaboration with colleagues in France and Taiwan, provide compelling new evidence that this component for life was found to be generated in outer space and delivered to Earth in its first one billion years by meteorites or comets. The phosphorus compounds were then incorporated in biomolecules found in cells in living beings on Earth.

The breakthrough research is outlined in “An Interstellar Synthesis of Phosphorus Oxoacids,” authored by UH Manoa graduate student Andrew Turner, now assistant professor at the University of Pikeville, and UH Manoa chemistry Professor Ralf Kaiser in the September issue of Nature Communications.

According to the study, phosphates and diphosphoric acid are two major elements that are essential for these building blocks in molecular biology. They are the main constituents of chromosomes, the carriers of genetic information in which DNA is found. Together with phospholipids in cell membranes and adenosine triphosphate, which function as energy carriers in cells, they form self-replicating material present in all living organisms.

In an ultra-high vacuum chamber cooled down to 5 K (-450°F) in the W.M. Keck Research Laboratory in Astrochemistry at UH Manoa, the Hawaii team replicated interstellar icy grains coated with carbon dioxide and water, which are ubiquitous in cold molecular clouds, and phosphine. When exposed to ionizing radiation in the form of high-energy electrons to simulate the cosmic rays in space, multiple phosphorus oxoacids like phosphoric acid and diphosphoric acid were synthesized via non-equilibrium reactions.

“On Earth, phosphine is lethal to living beings,” said Turner, lead author. “But in the interstellar medium, an exotic phosphine chemistry can promote rare chemical reaction pathways to initiate the formation of biorelevant molecules such as oxoacids of phosphorus, which eventually might spark the molecular evolution of life as we know it.”

Kaiser added, “The phosphorus oxoacids detected in our experiments by combination of sophisticated analytics involving lasers, coupled to mass spectrometers along with gas chromatographs, might have also been formed within the ices of comets such as 67P/Churyumov-Gerasimenko, which contains a phosphorus source believed to derive from phosphine.” Kaiser says these techniques can also be used to detect trace amounts of explosives and drugs.

“Since comets contain at least partially the remnants of the material of the protoplanetary disk that formed our solar system, these compounds might be traced back to the interstellar medium wherever sufficient phosphine in interstellar ices is available,” said Cornelia Meinert of the University of Nice (France).

Upon delivery to Earth by meteorites or comets, these phosphorus oxoacids might have been available for Earth’s prebiotic phosphorus chemistry. Hence an understanding of the facile synthesis of these oxoacids is essential to untangle the origin of water-soluble prebiotic phosphorus compounds and how they might have been incorporated into organisms not only on Earth, but potentially in our universe as well.

Turner and Kaiser worked with Meinert and Agnes Chang of National Dong Hwa University (Taiwan) on this project.

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Materials provided by University of Hawaii at Manoa. Note: Content may be edited for style and length.

Until recently, the motion of electrons at the atomic scale was inscrutable and inaccessible. Lasers with ultrafast pulses have provided tools to monitor and control electrons with sub-atomic resolution, and has allowed scientists to get familiar with real-time electron dynamics. One of the new possibilities is to use these laser pulses to generate customized emissions.

Emission are the outcome of meandering excited electrons. When a strong laser light shines on helium atoms, their electrons are free to temporarily escape from their parent atoms. As the laser is turned off, on the way back, these meandering electrons could either recombine with their parents straight away, or keep on “floating” nearby. The fast return of electrons is part of the high-harmonic generation, while the “floating” is called frustrated tunneling ionization (FTI). In both cases, the net result is the emission of light with a specific wavelength. In this study, IBS researchers have produced coherent extreme-ultraviolet radiation via FTI for the first time.

IBS researchers were able to control the trajectory of electrons by manipulating characteristics of the laser pulse. In FTI, the electrons travel a much longer trajectory than in high harmonic generation, and thus are more sensitive to variations of the laser pulse. For example, the team were able to control the direction of the emitted radiation by playing with the wavefront rotation of the laser beam (using spatially chirped laser pulses).

“We used IBS’ state-of-the-art laser technology to control the movement of the meandering electrons. We could identify a completely new coherent extreme-ultraviolet emission that was generated. We understood the fundamental mechanism of the emission, but there are still many things to investigate, such as phase matching and divergence control issues. These issues should be solved to develop a strong extreme-ultraviolet light source. Also, it is an interesting scientific issue to see whether the emission is generated from molecules, as it could provide information on the molecular structure and dynamics,” explains the group leader, KIM Kyung Taec.

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Materials provided by Institute for Basic Science. Original written by Letizia Diamante. Note: Content may be edited for style and length.