Research Now - Winter 2018
Bacteria change a liquid's properties and escape entrapment
A flexible tail allows swimming bacteria to thin the surrounding liquid and to free themselves when trapped along walls or obstacles. This finding could influence how bacterial growth on medical, industrial, and agricultural surfaces is controlled. The new study by researchers at Penn State used mathematical models to understand how bacteria with flagella—a collection of spinning hairs used for propulsion that act together like a tail—overcome forces from the flow of a liquid and navigate complex environments.
“We know from recent experimental studies that bacteria can reduce the effective viscosity— the internal friction—of a solution, which helps them move more easily,” said Mykhailo Potomkin, research associate in mathematics at Penn State and an author of the study.
Using a mathematical model, the research team demonstrated that flexible flagella allow bacteria to overcome local forces between molecules, reducing viscosity and effectively thinning the liquid.
“In order to understand whether we can control the viscosity of a solution, we need to understand how bacteria control it,” said Igor Aronson, Holder of the Huck Chair and professor of biomedical engineering, chemistry, and mathematics at Penn State and senior author of the study.
Read the full story, "Flexible flagella fight flow: Bacteria change a liquid’s properties and escape entrapment".
Potential new target for antimalarial drugs identified
A newly described protein could be an effective target for combatting drug- resistant malaria parasites. The protein, the transcription factor PfAP2-I, regulates a number of genes involved with the parasite’s invasion of red blood cells, a critical part of the parasite’s complex life cycle that could be targeted by new antimalarial drugs.
“The reality is that there are resistant parasites to every known antimalarial drug,” said Manuel Llinás, professor of biochemistry and molecular biology at Penn State and lead author of the study. “We need new drugs targeting different aspects of parasite biology.”
Nearly half of the world’s population lives in areas at risk of transmitting malaria, a serious and sometimes fatal disease that produces symptoms such as fevers, chills, and flu-like illness.
“Quite simply, if you prevent the malaria parasite from invading red blood cells, you prevent any disease,” said Llinás.
PfAP2-I is the first known regulator of invasion genes in Plasmodium falciparum— the species that causes the deadliest form of malaria. “Disrupting PfAP2-I would prevent the invasion program from ever getting turned on in the first place,” he said.
Read the full story, "Potential new target for anti-malarial drugs identified."
New planet found to be hotter than most stars
A newly discovered Jupiter-like world is so hot that even its nights are like the flame of a welding torch. The gas giant has a “year” only one and a half days long and may have a tail like a comet. Planet KELT-9b is hotter than most stars. With a day-side temperature of more than 7,800 degrees Fahrenheit (4,600 Kelvin), it is only about 2,000 degrees Fahrenheit (1,200 Kelvin) cooler than our own sun.
“At these temperatures, the fundamental component of KELT-9b’s atmosphere will be blasted apart into individual atoms during the day,” said Thomas Beatty, a research scientist at Penn State and a coauthor of the study. “Then as night falls, all those hydrogen atoms will try and get back together, creating an inferno at dusk. On Earth, this same process is used to create one of the hottest welding flames known,” he said.
An international research team including astronomers from Ohio State, Vanderbilt, and Penn State describes this planet and some of its very unusual features in a recent issue of the journal Nature.
Read the full story, "New planet found to be hotter than most stars".
Gravitational Waves Detected
Scientists worldwide and at Penn State have observed ripples in the fabric of space-time, called gravitational waves, arriving at Earth from a cataclysmic event in the distant universe five times since September 2015. These observations by the Laser Interferometer Gravitational-wave Observatory (LIGO) detectors confirm a major prediction of Albert Einstein’s general theory of relativity, published in 1916, and open an unprecedented new window onto the cosmos.
Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. The first four detections were the result of two merging black holes. Prior to these detections, the collision of two black holes had been predicted but never observed. The most recent detection was generated from the birth of a new black hole created by the merger of two neutron stars.
Seven Penn Staters were co-authors of the paper that described this historic first-ever detection of gravitational waves, including Lee Samuel Finn, professor of physics and of astronomy and astrophysics, and Chad Hanna, assistant professor of physics and of astronomy and astrophysics and Freed Early Career Professor at Penn State. An additional six researchers have since joined Penn State’s LIGO research team.
“This new achievement indicates that LIGO’s success in detecting gravitational waves truly has opened the door to an entirely new field of astrophysics research,” said Hanna.
The last two detections were also made by the Virgo Gravitational-Wave Observatory. This marks the beginning of a new era of “multi-messenger” as well as “multi-wavelength” space exploration—an era when gravitational-wave detectors are triggering a global network of other types of instruments to focus their special detection powers simultaneously on one fleetingly explosive point in space.
Read the full story, "Gravitational waves detected."
New, more sensitive sensor for evaluating drug safety
A new technique for evaluating drug safety can detect stress on cells at earlier stages than conventional methods. The new method uses a fluorescent sensor that is turned on in a cell when misfolded proteins begin to aggregate— an early sign of cellular stress. The method can be adapted to detect protein aggregates caused by other toxins as well as diseases such as Alzheimer’s or Parkinson’s.
“Drug-induced protein stress in cells is a key factor in determining drug safety,” said Xin Zhang, assistant professor of chemistry and of biochemistry and molecular biology at Penn State and the senior author of the study. “Drugs can cause proteins to misfold and clump together into aggregates that can eventually kill the cell. We set out to develop a system that can detect these aggregates at very early stages using technology that is affordable and accessible to many laboratories.”
The new system is the first to use a fluorescent sensor that is not turned on until the misfolded proteins begin to aggregate. The researchers designed an unstable protein—called AgHalo—that is tagged with a special fluorescent dye that becomes active in a hydrophobic (i.e., water-repellent) environment. When the AgHalo protein begins to misfold and aggregate, the dye can interact with the usually hidden hydrophobic portions of the protein and begin to fluoresce.
Read the full story, "New, more sensitive sensor for evaluating drug safety".
Evaluating reproducibility of genome organization studies
A new statistical method to evaluate the reproducibility of data from Hi-C—a cutting- edge tool for studying how the genome works in three dimensions inside of a cell—will help ensure that the data in these “big data” studies is reliable.
“Hi-C captures the physical interactions among different regions of the genome,” said Qunhua Li, assistant professor of statistics at Penn State and lead author of the study. “These interactions play a role in determining what makes a muscle cell a muscle cell instead of a nerve or cancer cell. However, standard measures to assess data reproducibility often cannot tell if two samples come from the same cell type or from completely unrelated cell types. This makes it difficult to judge if the data is reproducible. We have developed a novel method to accurately evaluate the reproducibility of Hi-C data, which will allow researchers to more confidently interpret the biology from the data.”
The new method, called HiCRep, developed by a team of researchers at Penn State and the University of Washington, is the first to account for a unique feature of Hi-C data—interactions between regions of the genome that are close together are far more likely to happen by chance and therefore create spurious, or false, similarity between unrelated samples.
Read the full story, "Evaluating reproducibility of genome organization studies".
Viruses up their game in arms race with immune system
In a classic example of the evolutionary arms race between a host and a pathogen, the myxoma virus—introduced to control the rabbit population in Australia in 1950—has developed a novel and deadly ability to suppress the immune response of its host rabbits. New research shows that viruses collected in the 1990s are much more effective at shutting down the immune systems of rabbits that have never been exposed to the virus than are viruses from the 1950s.
“When a host develops resistance to a virus, the virus will often evolve ways to evade the host’s immune response,” said Andrew Read, Evan Pugh Professor of Biology and Entomology and Eberly Professor of Biotechnology at Penn State and an author of the study. “Instead of hiding from the rabbit’s immune response, the myxoma virus has evolved ways to directly suppress it, leading to the development of a virus that is even more deadly to non-resistant rabbits.”
A paper describing the new study appears the week of August 14, 2017, in the journal Proceedings of the National Academy of Sciences. The research suggests that efforts to artificially increase resistance to a virus through selective breeding, genetic engineering, or immunization—unless they completely prevent transmission of the virus— could accelerate the arms race, producing even more-virulent viruses.
Read the full story, "Viruses up their game in arms race with immune system".