Impossible Possibilities

Fasting boosts stem cells' regenerative capacity...

2018-05-10T20:01:00.003-04:00

Intestinal stem cells from mice that fasted for 24 hours, at right, produced much more substantial intestinal organoids than stem cells from mice that did not fast, at left.
Credit: Maria Mihaylova and Chia-Wei Cheng

As people age, their intestinal stem cells begin to lose their ability to regenerate. These stem cells are the source for all new intestinal cells, so this decline can make it more difficult to recover from gastrointestinal infections or other conditions that affect the intestine.

This age-related loss of stem cell function can be reversed by a 24-hour fast, according to a new study from MIT biologists. The researchers found that fasting dramatically improves stem cells' ability to regenerate, in both aged and young mice.

In fasting mice, cells begin breaking down fatty acids instead of glucose, a change that stimulates the stem cells to become more regenerative. The researchers found that they could also boost regeneration with a molecule that activates the same metabolic switch. Such an intervention could potentially help older people recovering from GI infections or cancer patients undergoing chemotherapy, the researchers say.

"Fasting has many effects in the intestine, which include boosting regeneration as well as potential uses in any type of ailment that impinges on the intestine, such as infections or cancers," says Omer Yilmaz, an MIT assistant professor of biology, a member of the Koch Institute for Integrative Cancer Research, and one of the senior authors of the study. "Understanding how fasting improves overall health, including the role of adult stem cells in intestinal regeneration, in repair, and in aging, is a fundamental interest of my laboratory."

David Sabatini, an MIT professor of biology and member of the Whitehead Institute for Biomedical Research, is also a senior author of the paper, which appears in the May 3 issue of Cell Stem Cell.

"This study provided evidence that fasting induces a metabolic switch in the intestinal stem cells, from utilizing carbohydrates to burning fat," Sabatini says. "Interestingly, switching these cells to fatty acid oxidation enhanced their function significantly. Pharmacological targeting of this pathway may provide a therapeutic opportunity to improve tissue homeostasis in age-associated pathologies."

The paper's lead authors are Whitehead Institute postdoc Maria Mihaylova and Koch Institute postdoc Chia-Wei Cheng.

Boosting regeneration

For many decades, scientists have known that low caloric intake is linked with enhanced longevity in humans and other organisms. Yilmaz and his colleagues were interested in exploring how fasting exerts its effects at the molecular level, specifically in the intestine.

Intestinal stem cells are responsible for maintaining the lining of the intestine, which typically renews itself every five days. When an injury or infection occurs, stem cells are key to repairing any damage. As people age, the regenerative abilities of these intestinal stem cells decline, so it takes longer for the intestine to recover.

"Intestinal stem cells are the workhorses of the intestine that give rise to more stem cells and to all of the various differentiated cell types of the intestine. Notably, during aging, intestinal stem function declines, which impairs the ability of the intestine to repair itself after damage," Yilmaz says. "In this line of investigation, we focused on understanding how a 24-hour fast enhances the function of young and old intestinal stem cells."

After mice fasted for 24 hours, the researchers removed intestinal stem cells and grew them in a culture dish, allowing them to determine whether the cells can give rise to "mini-intestines" known as organoids.

The researchers found that stem cells from the fasting mice doubled their regenerative capacity.

"It was very obvious that fasting had this really immense effect on the ability of intestinal crypts to form more organoids, which is stem-cell-driven," Mihaylova says. "This was something that we saw in both the young mice and the aged mice, and we really wanted to understand the molecular mechanisms driving this."

Metabolic switch

Further studies, including sequencing the messenger RNA of stem cells from the mice that fasted, revealed that fasting induces cells to switch from their usual metabolism, which burns carbohydrates such as sugars, to metabolizing fatty acids. This switch occurs through the activation of transcription factors called PPARs, which turn on many genes that are involved in metabolizing fatty acids.

The researchers found that if they turned off this pathway, fasting could no longer boost regeneration. They now plan to study how this metabolic switch provokes stem cells to enhance their regenerative abilities.

They also found that they could reproduce the beneficial effects of fasting by treating mice with a molecule that mimics the effects of PPARs. "That was also very surprising," Cheng says. "Just activating one metabolic pathway is sufficient to reverse certain age phenotypes."

The findings suggest that drug treatment could stimulate regeneration without requiring patients to fast, which is difficult for most people. One group that could benefit from such treatment is cancer patients who are receiving chemotherapy, which often harms intestinal cells. It could also benefit older people who experience intestinal infections or other gastrointestinal disorders that can damage the lining of the intestine.

The researchers plan to explore the potential effectiveness of such treatments, and they also hope to study whether fasting affects regenerative abilities in stem cells in other types of tissue.

Story Source:

Materials provided by Massachusetts Institute of Technology.

Journal Reference:

Maria M. Mihaylova, Chia-Wei Cheng, Amanda Q. Cao, Surya Tripathi, Miyeko D. Mana, Khristian E. Bauer-Rowe, Monther Abu-Remaileh, Laura Clavain, Aysegul Erdemir, Caroline A. Lewis, Elizaveta Freinkman, Audrey S. Dickey, Albert R. La Spada, Yanmei Huang, George W. Bell, Vikram Deshpande, Peter Carmeliet, Pekka Katajisto, David M. Sabatini, Ömer H. Yilmaz. Fasting Activates Fatty Acid Oxidation to Enhance Intestinal Stem Cell Function during Homeostasis and Aging. Cell Stem Cell, 2018; 22 (5): 769 DOI: 10.1016/j.stem.2018.04.001

Massachusetts Institute of Technology. (2018, May 3). Fasting boosts stem cells' regenerative capacity: A drug treatment that mimics fasting can also provide the same benefit, study finds. ScienceDaily. Retrieved May 10, 2018 from www.sciencedaily.com/releases/2018/05/180503142852.htm

Risk of HIV transmission higher with anal intercourse....

2018-05-10T19:59:00.001-04:00

A person is more likely to get infected by HIV through anal intercourse than vaginal, but no one knows quite why. A new study by scientists at the Gladstone Institutes shows that infection sites could affect the immune system's response to a virus and the way the virus spreads through the body.

The study, published in Mucosal Immunology, aimed to understand how the immune system responds to a virus when it enters the body through different points. The researchers focused particularly on common routes of sexual transmission of viruses, such as the lower female reproductive tract and the lower gastrointestinal tract that includes the large intestine and the anus.

These mucosal barriers -- the body's openings lined with a membrane called mucosa -- are responsible for distinguishing between harmless bacteria that normally reside in us and potentially dangerous pathogens, as well as other substances, such as food or sperm.

"Our body is constantly trying to balance between tolerating harmless elements and defending us against possible threats," said Shomyseh Sanjabi, PhD, assistant investigator at Gladstone who led the study. "We wanted to learn whether the mechanisms that allow the body to be tolerant would affect its ability to elicit a protective immune response when needed. And, whether the process was different depending on the virus's point of entry."

Sanjabi's team discovered that, in fact, the body's reaction is different based on the infection site. They showed that the vaginal and rectal cavities activate a distinct immune response to the same pathogen.

Differences between Natural Routes of Infection

To conduct the study, Sanjabi and her team created a new model of viral infection through the rectum that uses lymphocytic choriomeningitis virus (LCMV), a rodent virus often used in research to model other pathogens. They then compared their findings to their previous work on vaginal infection by LCMV.

In 2016, they showed that vaginal infection causes a delayed response by protective cells. As a result, the immune system takes longer to clear the virus from the female reproductive tract. They also noticed that the virus stayed in the vagina and didn't spread to other parts of the body.

In contrast, the new study indicates that, after infection through the rectum, the virus rapidly spreads throughout the body. The scientists also found that the virus wasn't being carried through the blood. Instead, LCMV infects the body's own immune cells, which in turn spread the virus systemically. Interestingly, this is the same dissemination process used by the HIV virus.

"Our group was the first to recreate and compare these natural routes of viral infection," said Martin Trapecar, PhD, first author of the study and former postdoctoral scholar in Sanjabi's laboratory at Gladstone. "We concluded that the initial immune response elicited depends on the route of infection, and can actually dictate the dissemination of the virus. This is a novel concept, because we used to think once the virus entered the body, it would simply get into the blood and spread."

The researchers revealed that mucosal barriers have different tolerance mechanisms that affect the immune system's response to invading pathogens. In addition, they showed that once a virus breaches one of the barriers, early events in the body's response to that virus can play a key role in determining the outcome of an infection.

New Insights to Study and Prevent Viruses

The new study provides a much better understanding of how the immune system responds to a pathogen to protect the body and how a virus spreads once it enters the vaginal or rectal mucosa. These findings have general implications for the mechanism of sexual transmission and dissemination of many viruses, including HIV and Zika.

"Knowing the route each virus takes when it infects people is important," said Sanjabi, who is also an assistant professor of microbiology and immunology at UC San Francisco. "Our findings could change the way other scientists study viruses, and might ultimately be key to targeting treatments."

Results from Sanjabi's study could also impact efforts to develop vaccines against various viruses. Recognizing the differences in immune response will be crucial to defend people who may get infected through various routes of sexual transmission.

The paper "B cells are the predominant mediators of early systemic viral dissemination during rectal LCMV infection" was published in Mucosal Immunology. Other authors include Frank Wu, research associate in Sanjabi's laboratory, and former Gladstone trainees Shahzada Khan and Benjamin Cohn.

The research was supported by the National Institutes of Health, the Hellman Fellows Fund, the UCSF-Gladstone Center for AIDS Research (CFAR), and the Creative and Novel Ideas in Research (CNIHR) Program.

Story Source:

Materials provided by Gladstone Institutes.

Journal Reference:

Martin Trapecar, Shahzada Khan, Benjamin L. Cohn, Frank Wu, Shomyseh Sanjabi. B cells are the predominant mediators of early systemic viral dissemination during rectal LCMV infection. Mucosal Immunology, 2018; DOI: 10.1038/s41385-018-0009-4

Gladstone Institutes. (2018, February 20). Infection site affects how a virus spreads through the body: Different routes of sexual transmission affect the immune system's response to a virus, shows new study. ScienceDaily. Retrieved May 10, 2018 from www.sciencedaily.com/releases/2018/02/180220104104.htm

Sex after 65: Poll finds links to health, gender differences, lack of communication...

2018-05-10T19:37:00.000-04:00

Key findings from the May 2018 National Poll on Healthy Aging report, on sexual health after age 65.
Credit: University of Michigan

*The take home:

Majority are satisfied with their sex lives; nearly 1 in 5 older men use medications or supplements, U-M/AARP National Poll on Healthy Aging finds.

A new poll busts stereotypes about the sex lives of older Americans -- and reveals gender and health-related divides on key aspects of sexual health, while highlighting the need for more people to talk with their health providers about sexual issues.

Forty percent of people between the ages of 65 and 80 are sexually active, according to the new findings from the National Poll on Healthy Aging. Nearly three-quarters of people in this age range have a romantic partner and 54 percent of those with a partner are sexually active.

Whether or not they have an active sex life, nearly two-thirds of older adults say they're interested in sex, and more than half say sex is important to their quality of life.

And when asked if they are satisfied with their current sex life, 73 percent of the nationally representative sample of 1,002 people polled said they were. The poll was conducted by the University of Michigan Institute for Healthcare Policy and Innovation, and sponsored by AARP and Michigan Medicine, U-M's academic medical center.

The poll explored how older adults might seek help or advice for sexual problems, and if they've talked with their doctors about their sexual health.

In all, 18 percent of older men and 3 percent of older women say they've taken medications or supplements to improve sexual function in the past two years. But only 17 percent of older adults said they have talked with their doctor or other health care provider about sexual health in the past two years. Most who had engaged in such discussions said they brought the topic up, suggesting the need for more proactive conversations by clinicians with their older patients.

"Sexual health among older adults doesn't get much attention but is linked closely to quality of life, health and well-being," says U-M's Erica Solway, Ph.D., co-associate director of the poll. "It's important for older adults and the clinicians who care for them to talk about these issues and about how age-related changes in physical health, relationships, lifestyles and responsibilities such as caregiving, affect them."

Gender, age and health status divides

Solway notes that the poll finds some sharp differences along health, age and gender lines.

For instance, compared with the 45 percent of respondents with excellent, very good, or good health who reported they were sexually active, only 22 percent of those who said they are in fair or poor health were sexually active. Only 28 percent of those with fair or poor health said they were extremely or very satisfied with their sex lives.

There are also differences within age groups. Those between the ages of 65 and 70 were nearly twice as likely as those in their late 70s to be sexually active. One-third of those in their late 60s said they were extremely or very interested in sex, compared with 19 percent of those in their late 70s.

The gender gaps that emerged reveal some differences that may create challenges for relationships. For instance, women were less likely than men to be sexually active -- 31 percent overall, compared with 51 percent of men -- but were more likely to be extremely or very satisfied with their sex lives. And while 84 percent of older men said sex was an important part of a romantic relationship, 69 percent of older women agreed with that statement.

But the biggest gender difference was the percentage of those who said they were extremely or very interested in sex. Half of men aged 65 to 80 said they had this level of interest, compared with just 12 percent of women in the same age range.

"This survey just confirms that the need for and interest in sexual intimacy doesn't stop at a certain age," says Alison Bryant, Ph.D., senior vice president of research for AARP. "Although most older adults say that they would talk with their doctor about sexual concerns, health care providers should routinely be asking all of their older patients about their sexual health and not assume that bringing up the issue will offend or embarrass them."

A key takeaway from the poll, Solway notes, is that there appears to be opportunity for more proactive conversations between providers and their older patients about sexual health.

In all, 62 percent of the older adults polled said that if they were having a problem with their sexual health, they would talk with their health provider about it, yet only 17 percent had actually done so in the past two years. The majority (88 percent) of those who had talked with their provider about their sexual health said they were comfortable doing so.

The poll results are based on answers from a nationally representative sample of 1,002 people ages 65 to 80. The poll respondents answered a wide range of questions online. Questions were written, and data interpreted and compiled, by the IHPI team. Laptops and Internet access were provided to poll respondents who did not already have it.

A full report of the findings and methodology is available at http://www.healthyagingpoll.org, along with past National Poll on Healthy Aging reports.

Story Source:

Materials provided by Michigan Medicine - University of Michigan.

Michigan Medicine - University of Michigan. (2018, May 3). Sex after 65: Poll finds links to health, gender differences, lack of communication: Majority are satisfied with their sex lives; nearly 1 in 5 older men use medications or supplements, U-M/AARP National Poll on Healthy Aging finds. ScienceDaily. Retrieved May 10, 2018 from www.sciencedaily.com/releases/2018/05/180503085606.htm

Underwater acoustic ground cloak designed...

2018-05-10T19:02:00.004-04:00

Profile picture of the assembled perforated plate ground cloak.
Credit: Peter Kerrian

Cloaking devices play a pivotal role in many sci-fi television programs. Scientists are now working to take this technology from the dramatic realm of science fiction and make it real. Amanda D. Hanford, at Pennsylvania State University, is taking the introductory steps to make acoustic ground cloaks. These materials redirect approaching waves around an object without scattering the wave energy, concealing the object from the sound waves.

During the 175th Meeting of the Acoustical Society of America, being held May 7-11, 2018, in Minneapolis, Minnesota, Hanford will describe the physics behind an underwater acoustic shield designed in her lab.

Hanford and her team set out to engineer a metamaterial that can allow the sound waves to bend around the object as if it were not there. Metamaterials commonly exhibit extraordinary properties not found in nature, like negative density. To work, the unit cell -- the smallest component of the metamaterial -- must be smaller than the acoustic wavelength in the study.

"These materials sound like a totally abstract concept, but the math is showing us that these properties are possible," Hanford said. "So, we are working to open the floodgates to see what we can create with these materials."

To date, most acoustic metamaterials have been designed to deflect sound waves in air. Hanford decided to take this work one step further and accept the scientific challenge of trying the same feat underwater. Acoustic cloaking underwater is more complicated because water is denser and less compressible than air. These factors limit engineering options.

After multiple attempts, the team designed a 3-foot-tall pyramid out of perforated steel plates. They then placed the structure on the floor of a large underwater research tank. Inside the tank, a source hydrophone produced acoustic waves between 7,000 Hz and 12,000 Hz, and several receiver hydrophones around the tank monitored reflected acoustic waves.

The wave reflected from the metamaterial matched the phase of the reflected wave from the surface. Additionally, the amplitude of the reflected wave from the cloaked object decreased slightly. These results demonstrate that this material could make an object appear invisible to underwater instruments like sonar.

Using linear coordinate transformation, the researchers were able to map the flat surface of the bottom of the tank and determined that space was compressed into two triangular cloaking regions consisting of the engineered metamaterial.

These results show potential to contribute to real-world applications, such as acoustic materials to dampen sound and appear invisible underwater.

Penn State University researchers Dean E. Capone, Ph.D., and Benjamen S. Beck, Ph.D., along with Hanford's former graduate student Peter Kerrian, Ph.D., also contributed to this project.

Story Source:

Materials provided by Acoustical Society of America.

Acoustical Society of America. (2018, May 10). Underwater acoustic ground cloak designed: Researchers engineer material with properties not typically found in nature, concealing object from sound waves. ScienceDaily. Retrieved May 10, 2018 from www.sciencedaily.com/releases/2018/05/180510081555.htm

Marriage vs. The Ph.D. For those of you considering one or the other, consult this handy chart...

2018-05-10T18:49:00.002-04:00

I was looking back through posts trying to get rid of some of the errors and found this oldie but goody...Still true 😊 In my opinion, a Ph.D. is still a better investment.

Radar reveals details of mountain collapse after North Korea's most recent nuclear test

2018-05-10T18:24:00.002-04:00

3-D displacements derived from radar imagery with arrows indicating horizontal, color indicating vertical motions spanning the explosion and about 1 week of additional deformation. Black outline derived from ALOS-2 coherence loss indicates the substantial surface disturbance and large displacement gradients caused by the explosion over an area of about 9 square kilometers. Thin gray lines are topographic contours at 100-meter intervals. Red square in the upper right inset shows the location of Mt. Mantap in North Korea. Red stars indicate the locations of previous nuclear bomb tests. Beach balls show locations and focal mechanisms of the Mw 5.24 and Mw 4.47 events on Sept. 3, 2017
Credit: Earth Observatory of Singapore, Nanyang Technological University

As North Korea's president pledges to "denuclearize" the Korean peninsula, an international team of scientists is publishing the most detailed view yet of the site of the country's latest and largest underground nuclear test on Sept. 3, 2017.

The new picture of how the explosion altered the mountain above the detonation highlights the importance of using satellite radar imaging, called SAR (synthetic aperture radar), in addition to seismic recordings to more precisely monitor the location and yield of nuclear tests in North Korea and around the world.

The researchers -- Teng Wang, Qibin Shi, Shengji Wei and Sylvain Barbot from Nanyang Technological University in Singapore, Douglas Dreger and Roland Bürgmann from the University of California, Berkeley, Mehdi Nikkhoo from the German Research Centre for Geosciences in Potsdam, Mahdi Motagh from the Leibniz Universität Hannover, and Qi-Fu Chen from the Chinese Academy of Sciences in Beijing -- will report their results online this week in advance of publication in the journal Science.

That explosion took place under Mt. Mantap at the Punggye-ri nuclear test site in the country's north, rocking the area like a 5.2-magnitude earthquake. Based on seismic recordings from global and regional networks, and before-and-after radar measurements of the ground surface from Germany's TerraSAR-X and Japan's ALOS-2 radar imaging satellites, the team showed that the underground nuclear blast pushed the surface of Mt. Mantap outward by as much as 11 feet (3.5 meters) and left the mountain about 20 inches (0.5 meters) shorter.

By modelling the event on a computer, they were able to pinpoint the location of the explosion, directly under the mile-high summit, and its depth, between a quarter and a third of a mile (400-600 meters) below the peak.

They also located more precisely another seismic event, or aftershock, that occurred 8.5 minutes after the nuclear explosion, putting it some 2,300 feet (700 meters) south of the bomb blast. This is about halfway between the site of the nuclear detonation and an access tunnel entrance and may have been caused by the collapse of part of the tunnel or of a cavity remaining from a previous nuclear explosion.

"This is the first time the complete three-dimensional surface displacements associated with an underground nuclear test were imaged and presented to the public," said lead author Teng Wang of the Earth Observatory of Singapore at Nanyang Technological University.

Putting all of this together, the researchers estimate that the nuclear test, North Korea's sixth and the fifth inside Mt. Mantap, had a yield between 120 and 300 kilotons, about 10 times the strength of the bomb dropped by the United States on Hiroshima during World War II. That makes it either a small hydrogen, or fusion, bomb or a large atomic, or fission, bomb.

The new scenario differs from two reports last week, one of which has been accepted for publication in the journal Geophysical Research Letters, that pinpointed the blast nearly a kilometer to the northwest of the site identified in the new paper, and concluded that the blast rendered the entire mountain unfit for future nuclear tests.

"SAR really has a unique role to play in monitoring explosions because it is direct imaging of the local ground surface, unlike seismology, where you learn the nature of the source analyzing waves radiating outward from the event at distant stations," said Dreger, a UC Berkeley professor of earth and planetary science and a member of the Berkeley Seismological Laboratory. "SAR provides some measure of ground truthing of the location of the event, a very challenging thing to get at. This is the first time anyone has actually modeled the mechanics of an underground explosion using satellite and seismic data together."

"As opposed to standard optical imaging satellite imagery, SAR can be used to measure earth deformation day and night and under all weather conditions," added Dreger's colleague and co-author Roland Bürgmann, a UC Berkeley professor of earth and planetary science. "By precisely tracking the image pixel offsets in multiple directions, we were able to measure the full three-dimensional surface deformation of Mt. Mantap."

According to Dreger, the new information suggests the following scenario: The explosion occurred more than a quarter mile (450 meters) below the summit of Mt. Mantap, vaporizing granite rock within a cavity about 160 feet (50 meters) across -- the size of a football stadium -- and damaging a volume of rock about 1,000 feet (300 meters) across. The blast likely raised the mountain six feet (2 meters) and pushed it outward up to 11 feet (3-4 meters), though within minutes, hours or days the rock above the cavity collapsed to form a depression.

Eight and a half minutes after the bomb blast, a nearby underground cavity collapsed, producing the 4.5-magnitude aftershock with the characteristics of an implosion.

Subsequently, a much larger volume of fractured rock, perhaps 1 mile (1-2 kilometers) across, compacted, causing the mountain to subside to about 1.5 feet (0.5 meters) lower than before the blast.

"There may be continuing post-explosion compaction at the mountain. It takes time for these aseismic processes to occur," Dreger said.

While it is possible to discriminate explosions from natural earthquakes using seismic waveforms, the uncertainty can be large, Dreger said. Explosions often trigger nearby earthquake faults or other natural rock movements that make the seismic signals look earthquake-like, confusing the analysis. The SAR data revealed that additional constraints from the local static displacement can help to narrow down the source.

"I am hoping that by jointly analyzing the geodetic and seismic data, we will be able to improve discrimination between earthquakes and explosions, and certainly help with estimating the yield of an explosion and improving our estimation of source depth," Dreger said.

"This study demonstrates the capability of spaceborne remote sensing to help characterize large underground nuclear tests, if any, in the future," Wang said. "While surveillance of clandestine nuclear tests relies on a global seismic network, the potential of spaceborne monitoring has been underexploited."

The work was supported by the Singapore Ministry of Education and the National Research Foundation of Singapore, as well as the U.S. Air Force Research Laboratory.

Story Source:

Materials provided by University of California - Berkeley. Original written by Robert Sanders.

Journal Reference:

Teng Wang, Qibin Shi, Mehdi Nikkhoo, Shengji Wei, Sylvain Barbot, Douglas Dreger, Roland Bürgmann, Mahdi Motagh, Qi-Fu Chen. The rise, collapse, and compaction of Mt. Mantap from the 3 September 2017 North Korean nuclear test. Science, 2018 DOI: 10.1126/science.aar7230

University of California - Berkeley. (2018, May 10). Radar reveals details of mountain collapse after North Korea's most recent nuclear test: Seismic and geodetic data show displacement and subsidence, pinpoints detonation site, yield. ScienceDaily. Retrieved May 10, 2018 from www.sciencedaily.com/releases/2018/05/180510150045.htm

Why does the Sun's Corona sizzle at one million degrees Fahrenheit?

2018-05-10T17:34:00.000-04:00

A team of physicists, including NJIT's Gregory Fleishman, has discovered previously undetected energy in the Sun's coronal loops.

Credit: NASA’s Solar Dynamics Observatory

The Sun's corona, invisible to the human eye except when it appears briefly as a fiery halo of plasma during a solar eclipse, remains a puzzle even to scientists who study it closely. Located 1,300 miles from the star's surface, it is more than a hundred times hotter than lower layers much closer to the fusion reactor at the Sun's core.

A team of physicists, led by NJIT's Gregory Fleishman, has recently discovered a phenomenon that may begin to untangle what they call "one of the greatest challenges for solar modeling" -- determining the physical mechanisms that heat the upper atmosphere to 1 million degrees Fahrenheit and higher. Their findings, which account for previously undetected thermal energy in the corona, were recently published in the 123-year-old Astrophysical Journal, whose editors have included foundational space scientists such as Edwin Hubble.

"We knew that something really intriguing happens at the interface between the photosphere -- the Sun's surface -- and the corona, given the noticeable disparities in the chemical composition between the two layers and the sharp rise in plasma temperatures at this junction," notes Fleishman, a distinguished research professor of physics.

With a series of observations from NASA's space-based Solar Dynamics Observatory (SDO), the team has revealed regions in the corona with elevated levels of heavy metal ions contained in magnetic flux tubes -- concentrations of magnetic fields -- which carry an electrical current. Their vivid images, captured in the extreme (short wave) ultraviolet (EUV) band, reveal disproportionally large -- by a factor of five or more -- concentrations of multiply charged metals compared to single-electron ions of hydrogen, than exist in the photosphere.

The iron ions reside in what the team calls "ion traps" located at the base of coronal loops, arcs of electrified plasma directed by magnetic field lines. The existence of these traps, they say, implies that there are highly energetic coronal loops, depleted of iron ions, which have thus far eluded detection in the EUV range. Only metal ions, with their fluctuating electrons, produce emissions which make them visible.

"These observations suggest that the corona may contain even more thermal energy than is directly observed in the EUV range and that we have not yet accounted for," he says. "This energy is visible in other wavelengths, however, and we hope to combine our data with scientists who view it through microwaves and X-rays, such as scientists at NJIT's Expanded Owens Valley Solar Array, for example, to clarify mismatches in energy that we've been able to quantify so far."

There are various theories, none yet conclusive, that explain the sizzling heat of the corona: magnetic energy lines that reconnect in the upper atmosphere and release explosive energy and energy waves dumped in the corona, where they are converted to thermal energy, among others.

"Before we can address how energy is generated in the corona, we must first map and quantify its thermal structure," Fleishman notes.

"What we know of the corona's temperature comes from measuring EUV emissions produced by heavy ions in various states of ionization, which depends on their concentrations, as well as plasma temperature and density," he adds. "The non-uniform distribution of these ions in space and time appears to affect the temperature of the corona."

The metal ions enter the corona when variously sized solar flares destroy the traps, and they are evaporated into flux loops in the upper atmosphere.

Energy releases in solar flares and associated forms of eruptions occur when magnetic field lines, with their powerful underlying electric currents, are twisted beyond a critical point that can be measured by the number of turns in the twist. The largest of these eruptions cause what is known as space weather -- the radiation, energetic particles and magnetic field releases from the Sun powerful enough to cause severe effects in Earth's near environment, such as the disruption of communications, power lines and navigation systems.

It is only through recent advances in imaging capabilities that solar scientists can now take routine measurements of photospheric magnetic field vectors from which to compute the vertical component of electric currents, and, simultaneously, quantify the EUV emissions produced by heavy ions.

"Prior to these observations, we have only accounted for the coronal loops filled with heavy ions, but we could not account for flux tubes depleted of them," Fleishman says. "Now all of these poorly understood phenomena have a solid physical foundation that we can observe. We are able to better quantify the corona's thermal structure and gain a clearer understanding of why ion distribution in the solar atmosphere is non-uniform in space and variable in time."

Scientists at NJIT's Big Bear Solar Observatory (BBSO) have captured the first high-resolution images of magnetic fields and plasma flows originating deep below the Sun's surface, tracing the evolution of sunspots and magnetic flux ropes through the chromosphere before their dramatic appearance in the corona as flaring loops.

EUV emissions, however, can only be observed from space. The SDO, aboard a spacecraft launched in 2010, measures both magnetic field and EUV emissions from the whole Sun. The implications of the corona's temperature structure, and whether it allows the Sun to transfer more heat into the solar system, "is the subject of future study," Fleishman says.

Story Source:

Materials provided by New Jersey Institute of Technology. Original written by Tracey Regan.

Gregory D. Fleishman, Sophie Musset, Véronique Bommier, and Lindsay Glesener. Ion Traps at the Sun: Implications for Elemental Fractionation. Astrophysical Journal, 2018 DOI: 10.3847/1538-4357

New Jersey Institute of Technology. (2018, May 8). Why does the Sun's Corona sizzle at one million degrees Fahrenheit?. ScienceDaily. Retrieved May 10, 2018 from www.sciencedaily.com/releases/2018/05/180508131011.htm

Physicists find signs of a time crystal...

2018-05-10T17:30:00.000-04:00

Yale physicists have uncovered hints of a time crystal -- a form of matter that "ticks" when exposed to an electromagnetic pulse -- in the last place they expected: a crystal you might find in a child's toy.

The discovery means there are now new puzzles to solve, in terms of how time crystals form in the first place.

Ordinary crystals such as salt or quartz are examples of three-dimensional, ordered spatial crystals. Their atoms are arranged in a repeating system, something scientists have known for a century.

Time crystals, first identified in 2016, are different. Their atoms spin periodically, first in one direction and then in another, as a pulsating force is used to flip them. That's the "ticking." In addition, the ticking in a time crystal is locked at a particular frequency, even when the pulse flips are imperfect.

Scientists say that understanding time crystals may lead to improvements in atomic clocks, gyroscopes, and magnetometers, as well as aid in building potential quantum technologies. The U.S. Department of Defense recently announced a program to fund more research into time crystal systems.

Yale's new findings are described in a pair of studies, one in Physical Review Letters and the other in Physical Review B. The studies represent the second known experiment observing a telltale signature for a discrete time crystal (DTC) in a solid. Previous experiments led to a flurry of media attention in the past year.

"We decided to try searching for the DTC signature ourselves," said Yale physics professor Sean Barrett, principal investigator for the two new studies. "My student Jared Rovny had grown monoammonium phosphate (MAP) crystals for a completely different experiment, so we happened to have one in our lab."

MAP crystals are considered so easy to grow that they are sometimes included in crystal growing kits aimed at youngsters. It would be unusual to find a time crystal signature inside a MAP crystal, Barrett explained, because time crystals were thought to form in crystals with more internal "disorder."

The researchers used nuclear magnetic resonance (NMR) to look for a DTC signature -- and quickly found it. "Our crystal measurements looked quite striking right off the bat," Barrett said. "Our work suggests that the signature of a DTC could be found, in principle, by looking in a children's crystal growing kit."

Another unexpected thing happened, as well. "We realized that just finding the DTC signature didn't necessarily prove that the system had a quantum memory of how it came to be," said Yale graduate student Robert Blum, a co-author on the studies. "This spurred us to try a time crystal 'echo,' which revealed the hidden coherence, or quantum order, within the system," added Rovny, also a Yale graduate student and lead author of the studies.

Barrett noted that his team's results, combined with previous experiments, "present a puzzle" for theorists trying to understand how time crystals form.

"It's too early to tell what the resolution will be for the current theory of discrete time crystals, but people will be working on this question for at least the next few years," Barrett said.

The National Science Foundation supported the research.

Story Source:

Materials provided by Yale University. Original written by Jim Shelton.

Journal References:

Jared Rovny, Robert L. Blum, Sean E. Barrett. Observation of Discrete-Time-Crystal Signatures in an Ordered Dipolar Many-Body System. Physical Review Letters, 2018; 120 (18) DOI: 10.1103/PhysRevLett.120.180603
Jared Rovny, Robert L. Blum, Sean E. Barrett. P31 NMR study of discrete time-crystalline signatures in an ordered crystal of ammonium dihydrogen phosphate. Physical Review B, 2018; 97 (18) DOI: 10.1103/PhysRevB.97.18430

Yale University. (2018, May 2). Physicists find signs of a time crystal. ScienceDaily. Retrieved May 10, 2018 from www.sciencedaily.com/releases/2018/05/180502120013.htm

Breeding benefits when love bites wombats on the butt

2018-05-10T17:13:00.002-04:00

Monitoring wombats for behaviors such as pacing and rump biting could help conservation efforts by increasing the success of captive breeding.

University of Queensland researchers have found increased pacing by female southern hairy-nosed wombats is an indicator they are 'in season'.

And female wombats are more likely to bite the rumps of the males in pre-copulatory behaviour at the most fertile phase of their reproductive cycle.

Associate Professor Stephen Johnston said researchers were trying to better understand the southern hairy-nosed wombat as a breeding model for their critically endangered northern cousins.

"With only about 200 northern hairy-nosed wombats remaining, being able to breed these animals may one day ensure the survival of the species," he said.

"There has been no captive breeding of the northern hairy-nosed wombat, and even the southern species fails to breed regularly in captivity."

Dr Johnston said the size and aggressive temperament of wombats made them difficult to work with, so behavioural indicators were a significant step forward.

"We have developed a way to map the reproductive cycle of the female wombat by measuring hormone levels in their urine," Dr Johnston said.

"Through round-the-clock monitoring over multiple breeding cycles, we detected subtle behavioural changes associated with the fluctuations in this hormonal mapping.

"These behaviours could be used to identify when animals in captivity should be brought together for breeding, serving as cues for animal husbandry managers in zoos and wildlife facilities with southern hairy-nosed wombats."

The research team, including Dr Alyce Swinbourne, worked with Australian Animals Care and Education, from their Safe Haven base at Mr Larcom in Central Queensland.

Dr Johnston said that detection of the most appropriate timing for successful mating in the wombat was important not only for natural conception in wombats, but also for the next step in the research program, which involves the development of assisted reproductive techniques such as artificial insemination.

Story Source:

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

Journal Reference:

Alyce M. Swinbourne, Clive J. C. Phillips, Tina Janssen, Allan Lisle, Tamara Keeley, Stephen D. Johnston. Reproductive biology of captive female southern hairy-nosed wombats (Lasiorhinus latifrons). Part 2: oestrous behaviour. Reproduction, Fertility and Development, 2018; DOI: 10.1071/RD17539

University of Queensland. (2018, May 9). Breeding benefits when love bites wombats on the butt. ScienceDaily. Retrieved May 10, 2018 from www.sciencedaily.com/releases/2018/05/180509104956.htm

Scientists train spider to jump on demand to discover secrets of animal movement

2018-05-10T17:12:00.000-04:00

Scientists have unlocked the secrets of how some predatory spiders catch their prey whilst hunting by successfully training one to jump different distances and heights for the first time.

The study, conducted by researchers at The University of Manchester, is the most advanced of its kind to date and first to use 3D CT scanning and high-speed, high-resolution cameras to record, monitor and analyse a spider's movement and behaviour.

The aim of the research is to answer the question of why jumping spider anatomy and behaviour evolved the way it did, and secondly, to use this improved understanding of spiders to imagine a new class of agile micro-robots that are currently unthinkable using today's engineering technologies.

The study is being published in the journal Nature Scientific Reports.

Dr Mostafa Nabawy, lead author of the study, says: "The focus of the present work is on the extraordinary jumping capability of these spiders. A jumping spider can leap up to six times its body length from a standing start. The best a human can achieve is about 1.5 body lengths. The force on the legs at take-off can be up to 5 times the weight of the spider -- this is amazing and if we can understand these biomechanics we can apply them to other areas of research."

The researchers trained the spider, which they nicknamed Kim, to jump different heights and distances on a humanmade platform in a laboratory environment. Kim belongs to a species of jumping arachnid known as Phidippus regius, or 'Regal Jumping Spider'. The team then recorded the jumps using ultra-high-speed cameras, and used high resolution micro CT scans to create a 3D model of Kim's legs and body structure in unprecedented detail.

The results show that this particular species of spider uses different jumping strategies depending on the jumping challenge it is presented with.

For example, to jump shorter, close-range distances Kim favoured a faster, lower trajectory which uses up more energy, but minimises flight time. This makes the jump more accurate and more effective for capturing its prey. But, if Kim is jumping a longer distance or to an elevated platform, perhaps to traverse rough terrain, she jumps in the most efficient way to reduce the amount of energy used.

Insects and spiders jump in a number of different ways, either using a spring like mechanism, direct muscle forces or using internal fluid pressure.

Scientists have known for more than 50 years that spiders use internal hydraulic pressure to extend their legs, but what isn't known is if this hydraulic pressure is actively used to enhance or replace muscle force when the spiders jump.

Dr Bill Crowther, co-author of the study, explains: "Our results suggest that whilst Kim can move her legs hydraulically, she does not need the additional power from hydraulics to achieve her extraordinary jumping performance. Thus, the role of hydraulic movement in spiders remains an open question."

Video: https://www.youtube.com/watch?v=C6PAClh1IZo

Story Source:

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

Journal Reference:

Mostafa R. A. Nabawy, Girupakaran Sivalingam, Russell J. Garwood, William J. Crowther, William I. Sellers. Energy and time optimal trajectories in exploratory jumps of the spider Phidippus regius. Scientific Reports, 2018; 8 (1) DOI: 10.1038/s41598-018-25227-9

University of Manchester. (2018, May 8). Scientists train spider to jump on demand to discover secrets of animal movement. ScienceDaily. Retrieved May 10, 2018 from www.sciencedaily.com/releases/2018/05/180508081459.htm

Uncovering the secret law of the evolution of galaxy clusters

2018-05-10T17:09:00.003-04:00

Analysis of gravitational lensing data by an international research team reveals that the evolution of galaxy clusters is dictated by a surprisingly simple law, which clearly shows that they are still growing.

As science enthusiasts around the world bid farewell last month to legendary cosmologist Stephen Hawking, researchers continue to make important discoveries about the evolution of galaxy clusters that capture the imagination.

Now, an international collaboration between Yutaka Fujita at Osaka University and researchers from Taiwan, Italy, Japan, and the United States found a new fundamental law that stipulates the evolution of galaxy clusters. They recently reported the study in The Astrophysical Journal.

Galaxy clusters are the largest celestial body in the Universe. However, it has been difficult to measure their size and mass accurately because they mainly consist of dark matter that we cannot observe directly. One way to observe the dark matter indirectly is to use the gravitational lensing effect based on Einstein's theory of relativity. Light rays from a galaxy behind a cluster are pulled by the gravity of the cluster as they pass through it, and their paths are bent. This is exactly the same effect as a lens, focusing the light of the distant galaxy and distorting its shape. If we can measure the distortion of the shape for many background galaxies, we can reveal the gravitational field of the cluster, and as a result, we can accurately measure its size and mass.

"One difficulty in our research," explains Keiichi Umetsu at Academia Sinica in Taiwan, "was that accurate measurements of the distortion were necessary." To overcome this problem, the research team has used precise observational data from NASA's Hubble Space Telescope and the Subaru Telescope operated by the National Astronomical Observatory of Japan.

Combining with gas temperature data from the Chandra X-ray satellite, the research group statistically examined those latest data and found that they conform to a simple law represented only by the size, mass, and gas temperature of clusters. Moreover, by making full use of computer simulations, they showed that clusters have grown over 4 to 8 billion years according to the law. Theoretically, the law means that those gigantic clusters are still in adolescence, growing by drawing a large amount of surrounding substances with their strong gravity.

"We've discovered the law that regulates the growth of clusters of galaxies," Fujita says. "Clusters have an internal structure uniquely created in an early growth spurt."

The law is so simple that we can use it to calibrate cluster mass-observable relations, which are a key ingredient for studying the cosmological laws of the Universe.

"Our research draws us closer to explaining the evolutionary history of clusters and the Universe," Fujita adds.

Story Source:

Materials provided by Osaka University.

Journal Reference:

Yutaka Fujita, Keiichi Umetsu, Elena Rasia, Massimo Meneghetti, Megan Donahue, Elinor Medezinski, Nobuhiro Okabe, Marc Postman. Discovery of a New Fundamental Plane Dictating Galaxy Cluster Evolution from Gravitational Lensing. The Astrophysical Journal, 2018; 857 (2): 118 DOI: 10.3847/1538-4357/aab8fd

Osaka University. (2018, April 24). Uncovering the secret law of the evolution of galaxy clusters: Analysis of gravitational lensing data by an international research team reveals that the evolution of galaxy clusters is dictated by a surprisingly simple law, which clearly shows that they are still growing. ScienceDaily. Retrieved May 10, 2018 from www.sciencedaily.com/releases/2018/04/180424093711.htm

Ebola detected in semen of survivors two years after infection

2018-05-10T03:47:00.000-04:00

Ebola virus RNA can persist in the semen of survivors more than two years after the onset of infection researchers at the University of North Carolina at Chapel Hill have found. The research team, which included investigators from Ohio-based Clinical Research Management and the ELWA Hospital in Liberia also observed the detection of Ebola virus RNA in the semen of men who had previously had a negative test of their semen in some cases.

These findings led the study team to suggest revision of the 2016 World Health Organization guidelines relating to the sexual transmission of Ebola, which calls for men who survive Ebola virus disease (EVD) to undertake measures such as abstinence and the use of condoms for at least 12 months after the onset of EVD or until their semen has tested negative for Ebola virus RNA twice. The study results were published in Open Forum Infectious Diseases.

Male participants enrolled in a longitudinal cohort study of Ebola survivors in Monrovia, Liberia, consented to donating semen. Of the 149 men who provided samples, 13 tested positive for Ebola virus RNA. Of these 13 men, 11 had positive results even two years after the onset of Ebola infection.

"Our finding of long term persistence and intermittent detection of viral RNA in semen suggests we need to change how we think about Ebola as it is no longer only an acute illness, but also one with potential long-term effects," said William A. Fischer II, M.D., an assistant professor in the UNC Division of Pulmonary and Critical Care Medicine and the study's co-author. "It is becoming clear that in some survivors, evidence of the virus can linger in the male genital tract for long periods of time with important potential implications for transmission."

Fischer notes that while there has been documented sexual transmission of Ebola earlier after acute infection, it is not known whether the presence of RNA serves as a correlate for infectious virus and if transmission this far out is possible.

The study team also reports that the men whose samples tested positive for Ebola virus RNA were more likely to be older than those with a negative result. Those who had Ebola virus RNA detected in their semen also complained of vision problems at a higher rate than male survivors without evidence of Ebola virus RNA in their semen. The researchers recommend future studies investigate the source of viral persistence and whether the detection of viral RNA signifies the presence of infectious virus.

The large Ebola outbreak in West Africa in 2014 to 2015 was devastating to the people in West Africa and beyond, said David A. Wohl, M.D., professor of Infectious Diseases at UNC and study co-author.

"However, the scale of the epidemic has allowed for researchers to gain better insights into the Ebola virus, including the potential persistence of the virus in certain compartments of the body, such as the genital tract," Wohl said.

The researchers stress that such studies must be conducted in a way that empowers the Ebola survivor community and avoids further stigmatization.

Story Source:
Materials provided by University of North Carolina Health Care.

Journal Reference:
William A Fischer II et al. Ebola Virus RNA Detection in Semen More than Two Years After Resolution of Acute Ebola Virus Infection. Open Forum Infectious Diseases, 2017 DOI: 10.1093/ofid/ofx155/4004818

University of North Carolina Health Care. "Ebola detected in semen of survivors two years after infection: Researchers suggest updating WHO guidelines and exploring aging." ScienceDaily. ScienceDaily, 2 August 2017. <www.sciencedaily.com/releases/2017/08/170802152532.htm>.

Dimethandrolone undecanoate shows promise as a male birth control pill

2018-05-10T03:01:00.000-04:00

A new birth control pill for men appears to be safe when used daily for a month, with hormone responses consistent with effective contraception, study researchers say. Their study results, in 83 men, will be presented Sunday at ENDO 2018, the Endocrine Society's 100th annual meeting in Chicago, Il.

Like the pill for women, the experimental male oral contraceptive -- called dimethandrolone undecanoate, or DMAU -- combines activity of an androgen (male hormone) like testosterone, and a progestin, and is taken once a day, said the study's senior investigator, Stephanie Page, M.D., PhD, professor of medicine at the University of Washington, Seattle, Wash.

"DMAU is a major step forward in the development of a once-daily 'male pill'," Page said. "Many men say they would prefer a daily pill as a reversible contraceptive, rather than long-acting injections or topical gels, which are also in development."

Progress toward a male birth control pill has been stymied because, according to Page, available oral forms of testosterone may cause liver inflammation, and they clear the body too quickly for once-daily dosing, thus requiring two doses a day. However, DMAU contains undecanoate, a long-chain fatty acid, which Page said slows this clearance. DMAU is being developed by the National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Human Development, which funded this study.

The study included 100 healthy men, ages 18 to 50 years, and took place at the University of Washington Medical Center and at Harbor-UCLA Medical Center in Torrance, CA (led by co-author Christina Wang, M.D.). The investigators tested three different doses of DMAU (100, 200, and 400 milligrams, or mg) and two different formulations inside the capsules (castor oil and powder). Each dose group included five subjects who were randomly assigned to receive an inactive placebo and another 12 to 15 men who received DMAU. Subjects took the drug or placebo for 28 days once daily with food. DMAU must be taken with food to be effective, Page noted.

A total of 83 men completed the study, including giving blood samples, for hormone and cholesterol testing, on the first and last days of the study.

At the highest dose of DMAU tested, 400 mg, subjects showed "marked suppression" of levels of their testosterone and two hormones required for sperm production. The low levels, Page said, are consistent with effective male contraception shown in longer-term studies.

"Despite having low levels of circulating testosterone, very few subjects reported symptoms consistent with testosterone deficiency or excess," Page said.

All groups taking DMAU did have weight gain and decreases in HDL ("good") cholesterol, both of which Page said were mild. All subjects passed safety tests, including markers of liver and kidney function.

"These promising results are unprecedented in the development of a prototype male pill," Page said. "Longer term studies are currently under way to confirm that DMAU taken every day blocks sperm production.

Story Source:

Materials provided by The Endocrine Society.

The Endocrine Society. (2018, March 18). Dimethandrolone undecanoate shows promise as a male birth control pill. ScienceDaily. Retrieved May 10, 2018 from www.sciencedaily.com/releases/2018/03/180318144834.htm

Apparently, there are advantages to having a wandering mind after all...

2015-02-24T20:21:00.000-05:00

Does your mind wander when performing monotonous, repetitive tasks? Of course! But daydreaming involves more than just beating back boredom. In fact, according to a new study published in the Proceedings of the National Academy of Sciences, a wandering mind can impart a distinct cognitive advantage.

Scientists at Bar-Ilan University are the first to demonstrate how an external stimulus of low-level electricity can literally change the way we think, producing a measurable up-tick in the rate at which daydreams -- or spontaneous, self-directed thoughts and associations -- occur. Along the way, they made another surprising discovery: that while daydreams offer a welcome "mental escape" from boring tasks, they also have a positive, simultaneous effect on task performance.

The new study was carried out in Bar-Ilan's Cognitive Neuroscience Laboratory supervised by Prof. Moshe Bar, part of the University's Gonda (Goldschmied) Multidisciplinary Brain Research Center which Prof. Bar also directs.

What Makes a Mind Wander?

While a far cry from the diabolical manipulation of dream content envisioned in "Inception" -- the science-fiction thriller starring Leonardo DiCaprio -- the Bar-Ilan University study is the first to prove that a generic external stimulus, unrelated to sensory perception, triggers a specific type of cognitive activity.

In the experiment -- designed and executed by Prof. Bar's post-doctoral researcher Dr. Vadim Axelrod -- participants were treated with transcranial direct current stimulation (tDCS), a non-invasive and painless procedure that uses low-level electricity to stimulate specific brain regions. During treatment, the participants were asked to track and respond to numerals flashed on a computer screen. They were also periodically asked to respond to an on-screen "thought probe" in which they reported -- on a scale of one to four -- the extent to which they were experiencing spontaneous thoughts unrelated to the numeric task they had been given.

The Brain-Daydream Connection

According to Prof. Bar -- a long-time faculty member at Harvard Medical School who has authored several studies exploring the link between associative thinking, memory and predictive ability -- the specific brain area targeted for stimulation in this study was anything but random.
"We focused tDCS stimulation on the frontal lobes because this brain region has been previously implicated in mind wandering, and also because is a central locus of the executive control network that allows us to organize and plan for the future," Bar explains, adding that he suspected that there might be a connection between the two.

As a point of comparison and in separate experiments, the researchers used tDCS to stimulate the occipital cortex -- the visual processing center in the back of the brain. They also conducted control studies where no tDCS was used.

While the self-reported incidence of mind wandering was unchanged in the case of occipital and sham stimulation, it rose considerably when this stimulation was applied to the frontal lobes. "Our results go beyond what was achieved in earlier, fMRI-based studies," Bar states. "They demonstrate that the frontal lobes play a causal role in the production of mind wandering behavior."

Improved "Cognitive Capacity" of the Wandering Mind

In an unanticipated finding, the present study demonstrated how the increased mind wandering behavior produced by external stimulation not only does not harm subjects' ability to succeed at an appointed task, it actually helps. Bar believes that this surprising result might stem from the convergence, within a single brain region, of both the "thought controlling" mechanisms of executive function and the "thought freeing" activity of spontaneous, self-directed daydreams.

"Over the last 15 or 20 years, scientists have shown that -- unlike the localized neural activity associated with specific tasks -- mind wandering involves the activation of a gigantic default network involving many parts of the brain," Bar says. "This cross-brain involvement may be involved in behavioral outcomes such as creativity and mood, and may also contribute to the ability to stay successfully on-task while the mind goes off on its merry mental way."

While it is commonly assumed that people have a finite cognitive capacity for paying attention, Bar says that the present study suggests that the truth may be more complicated.

"Interestingly, while our study's external stimulation increased the incidence of mind wandering, rather than reducing the subjects' ability to complete the task, it caused task performance to become slightly improved. The external stimulation actually enhanced the subjects' cognitive capacity."

Toward A Less-Mysterious Mind

Bar says that, in the future, he would be interested in studying how external stimulation might affect other cognitive behaviors, such as the ability to focus or perform multiple tasks in parallel. And while any therapeutic application of this technique is speculative at best, he believes that it might someday help neuroscientists understand the behavior of people suffering from low or abnormal neural activity.

In the meantime, Bar's team at the BIU Lab for Cognitive Neuroscience is pleased to note that in their work on mind wandering -- probably the most omnipresent internal cognitive function -- they have made the human brain just a little less mysterious

Journal Reference:

Vadim Axelrod, Geraint Rees, Michal Lavidor, Moshe Bar. Increasing propensity to mind-wander with transcranial direct current stimulation. Proceedings of the National Academy of Sciences, 2015; 201421435 DOI: 10.1073/pnas.1421435112

Bar-Ilan University. "Neuroscientists literally change the way we think: Advantages of a wandering mind." ScienceDaily. ScienceDaily, 23 February 2015.

Does your mind wander when performing monotonous, repetitive tasks? Of course! But daydreaming involves more than just beating back boredom. In fact, according to a new study a wandering mind can impart a distinct cognitive advantage.

How a wound closes at the cellular level ...

2015-02-23T22:28:00.000-05:00

For wounds to close, cells need to move collectively in one direction in a coordinated fashion. Until now the central molecular mechanism that allows cells to coordinate these movements over larger distances has been unclear. Now researchers from Heidelberg University and the Max Planck Institute for Intelligent Systems in Stuttgart have succeeded in decoding it. Collective cell migration is not only important in wound healing, but also in the development of the embryo and even of cancer. The results of their research, published in the journal "Nature Cell Biology," have tremendous implications for all three of these areas.

"The collective migration of cells and biological systems is one of the most important natural phenomena and occurs in nature at different levels and length scales. We have now identified the key molecular player and the related mechanism that controls the collective migration of epithelial cells, that is the covering layer of skin cells," explains Prof. Dr. Joachim Spatz of the Institute for Physical Chemistry at Heidelberg University and the Max Planck Institute for Intelligent Systems. In their investigation, the researchers introduce a complete molecular mechanism that focuses on the protein called Merlin. The results link intercellular mechanical forces to collective cell movements and also demonstrate how local interactions give rise to collective dynamics at the multicellular level. "They create an analogy with what we already know about collective movements observable in both the biological and physical world," explains Prof. Spatz.

The researcher compares the process of cell migration to running a marathon. "At the level of the organism, an individual in a collective consciously tries to align its movements with those of its neighbors, which involves orchestrated sensing and action." Within a cellular collective, these two processes are linked via signal transduction pathways. There is a lead cell in the collective, similar to the leader in a marathon. It is mechanically connected to its follower cells by cell-to-cell contacts. The forward motion of the lead cell puts mechanical tension on the follower cells, according to Spatz. The merlin protein senses this mechanical tension and initiates spatially polarized following movement. This transmits the mechanical tension among the follower cells from one cell to the next. The follower cells respond by forming 'leg-like' protrusions directed at the lead cell in order to move forward.

"Until now it has been unclear what molecular link connects these two events, sensing and action," says Joachim Spatz. "Our study now shows how the mechanosensitive Merlin protein converts cellular forces to collective cell motions by acting as a mechanochemical transducer. What's truly astonishing is that Merlin is the only protein in the responsible signal network that conveys this property to cellular collectives -- that there are no replacement mechanisms. If Merlin fails, the cells lose their ability to move collectively and trigger the related medically relevant, pathophysiological properties in the organism."

The major player in the study, Merlin, is also a known tumor suppressor that is responsible for several types of cancer. Merlin is also a regulator of the Hippo pathway, an important signal pathway in biology that controls cell proliferation and organ size. It has been preserved in evolution since the emergence of primitive multicellular organisms. "It's exciting to see a connection between these seemingly disparate fields, linked by a Merlin-mediated signaling mechanism," says the researcher.

Journal Reference:

Tamal Das, Kai Safferling, Sebastian Rausch, Niels Grabe, Heike Boehm, Joachim P. Spatz. A molecular mechanotransduction pathway regulates collective migration of epithelial cells. Nature Cell Biology, 2015; DOI: 10.1038/ncb3115

Heidelberg, Universität. "How a wound closes." ScienceDaily, 23 February 2015.

Epithelial cells move collectively out of their original shape (left) into the environment (right). Localization of Merlin is shown in green, the cell nuclei in red.

Credit: Max Planck Institute for Intelligent Systems

Long-term nitrogen fertilizer use disrupts plant-microbe mutualisms

2015-02-23T21:03:00.001-05:00

When exposed to nitrogen fertilizer over a period of years, nitrogen-fixing bacteria called rhizobia evolve to become less beneficial to legumes -- the plants they normally serve, researchers report in a new study.

These findings, reported in the journal Evolution, may be of little interest to farmers, who generally grow only one type of plant and can always add more fertilizer to boost plant growth. But in natural areas adjacent to farmland, where fertilizer runoff occurs, or in areas where nitrogen oxides from the burning of fossil fuels settle, a change in the quality of soil rhizobia could have "far-reaching ecological and environmental consequences," the researchers wrote.

"The nitrogen that we apply to agricultural fields doesn't stay on those fields, and atmospheric nitrogen deposition doesn't stay by the power plant that generates it," said University of Illinois plant biology professor Katy Heath , who led the study with Jennifer Lau , of Michigan State University. "So this work is not just about a fertilized soybean field. Worldwide, the nitrogen cycle is off. We've changed it fundamentally."

Not that long ago, before the advent of industrial fertilizers and the widespread use of fossil fuels, soil nitrogen was a scarce commodity. Some plants, the legumes, found a way to procure the precious nitrogen they needed -- from rhizobia.

"The rhizobia fix nitrogen -- from atmospheric nitrogen that we're breathing in and out all the time -- to plant-available forms," Heath said. "Plants can't just take it up from the atmosphere; they have to get it in the form of nitrate or ammonium."

In return, legumes shelter the rhizobia in their roots and supply them with carbon. This partnership benefits the bacteria and gives legumes an advantage in nitrogen-poor soils. Previous studies have shown that nitrogen fertilizers can affect the diversity of species that grow in natural areas, Heath said. In areas polluted with fertilizer runoff, for example, legumes decline while other plants become more common.

In the new analysis, Heath and her colleagues looked at six long-term ecological research fields at Michigan State University's Kellogg Biological Station. Two experimental plots were located in each of six different fields. One plot in each field had been fertilized with nitrogen for more than two decades; the other, a control plot, had never been fertilized.

The researchers isolated rhizobia from the nodules of legumes in fertilized and unfertilized plots. In a greenhouse experiment, they tested how these bacteria influenced legume growth and health. The researchers found that the plants grown with the nitrogen-exposed rhizobia produced 17 to 30 percent less biomass and significantly less chlorophyll than plants grown with rhizobia from the unfertilized plots.

A genetic analysis of the microbes revealed that the composition of the bacterial populations was similar between fertilized and unfertilized plots: The same families of rhizobia were present in each. But rhizobia from the fertilized plots had evolved in a way that made them less useful to the legumes, Heath said.

"This study tells us something about mutualisms and how they evolved," she said. "Mutualisms depend on this balance of trade between the partners, this special nitrogen-carbon economy in the soil, for example. And when the economy changes -- say when nitrogen is no longer scarce -- these mutualisms might go away."

Journal Reference:

Dylan J. Weese, Katy D. Heath, Bryn T. M. Dentinger, Jennifer A. Lau. Long-term nitrogen addition causes the evolution of less-cooperative mutualists. Evolution, 2015; DOI: 10.1111/evo.12594

University of Illinois at Urbana-Champaign. "Long-term nitrogen fertilizer use disrupts plant-microbe mutualisms." ScienceDaily. ScienceDaily, 23 February 2015.

Soil microbes known as rhizobia supply much-needed nitrogen to legumes such as clover (Trifolium species). In return, legumes shelter the rhizobia in nodules on their roots and provide them with carbon.

Credit: Julie McMahon

Who cares? Why evolution suggests parenting responsibility is seldom equally shared

2015-02-23T20:48:00.000-05:00

Why is caring for young shared unequally between the sexes in so many animal species? Research from the University of Bristol, UK suggests that small initial differences which predispose one sex to care more are exaggerated once the ability to care evolves. As a result, one sex evolves attributes -- such as mammary glands in female mammals or increased brain size in some fish -- that enhance the ability to care, and so this sex does most or all of the care.

Patterns of parenting in nature range from care by one parent only (seen in many mammals), to male/female biased care, to care by both parents (seen in many birds).

Parental care involves one of the fundamental conflicts of interest between the sexes. Care by either partner is beneficial to both partners as it increases the health and survival prospects of the common young; providing care is costly only to the caring individual. As a result, each partner does best in a situation where most of the care is provided by the other partner -- an outcome that is clearly impossible.

Differences in care can be explained by differences in the costs and benefits of caring with two factors currently considered to be the key drivers: certainty of parentage (which decreases the benefit of care for the less certain sex -- usually the male) and sexual selection (which increases the cost of care for the sex that can mate again faster).

Professor John McNamara, of the University of Bristol's School of Mathematics, and Dr Max Wolf of the Leibniz-Institute of Freshwater Ecology and Inland Fisheries, used a modelling approach to show that even in the complete absence of these factors, substantial differences in care are to be expected.

They found that sex differences in both the ability to care and levels of care are prone to spontaneously evolve as a result of the sexual conflict of interest over parental care and the co-evolutionary interaction between levels of care and ability to care.

Professor McNamara said: "While the coevolution of care and the ability to care thus predicts strong sex differences in care to emerge, it does not predict which sex is more likely to care. However, once other factors that give rise to even the slightest differences in the cost and benefits of care between the sexes, such as differences in certainty of parentage, are taken into account, a clear directionality emerges. The sex with the lower cost or higher benefit of care evolves to both be more able to care and to provide much higher levels of care than the other sex."

The findings, published today in Proceedings of the Royal Society B, thus suggest that the coevolution of levels of care and the ability to care may be a key factor underlying the evolution of sex differences in caring for young.

Journal Reference:

J. M. McNamara, M. Wolf. Sexual conflict over parental care promotes the evolution of sex differences in care and the ability to care. Proceedings of the Royal Society B: Biological Sciences, 2015; 282 (1803): 20142752 DOI: 10.1098/rspb.2014.2752

University of Bristol. "Who cares? Why evolution suggests parenting responsibility is seldom equally shared." ScienceDaily. ScienceDaily, 17 February 2015.

Small initial differences which predispose one sex to care more are exaggerated once the ability to care evolves. As a result, one sex evolves attributes -- such as pouches in female marsupials -- that enhance the ability to care, and so this sex does most or all of the care.

Credit: Image courtesy of University of Bristol

Clues to superbug evolution: Microbiologists sequence entire genome ofa Klebsiella pneumoniae strain

2014-09-23T18:57:00.001-04:00

Imagine going to the hospital with one disease and coming home with something much worse, or not coming home at all.

With the emergence and spread of antibiotic-resistance pathogens, healthcare-associated infections have become a serious threat. On any given day about one in 25 hospital patients has at least one such infection and as many as one in nine die as a result, according to the Centers for Disease Control and Prevention.

Consider Klebsiella pneumoniae, not typically a ferocious pathogen, but now armed with resistance to virtually all antibiotics in current clinical use. It is the most common species of carbapenem-resistant Enterobacteriaceae (CRE) in the United States. As carbapenems are considered the antibiotic of last resort, CREs are a triple threat for their resistance to nearly all antibiotics, high mortality rates and ability to spread their resistance to other bacteria.

But there is hope. A team of Sandia National Laboratories microbiologists for the first time recently sequenced the entire genome of a Klebsiella pneumoniae strain, encoding New Delhi Metallo-beta-lactamase (NDM-1). They presented their findings in a paper published in PLOS One, "Resistance Determinants and Mobile Genetic Elements of an NDM-1 Encoding Klebsiella pneumoniae Strain."

The Sandia team of Corey Hudson, Zach Bent, Robert Meagher and Kelly Williams is beginning to understand the bacteria's multifaceted mechanisms for resistance. To do this, they developed several new bioinformatics tools for identifying mechanisms of genetic movement, tools that also might be effective at detecting bioengineering.

"Once we had the entire genome sequenced, it was a real eye opener to see the concentration of so many antibiotic resistant genes and so many different mechanisms for accumulating them," explained Williams, a bioinformaticist. "Just sequencing this genome unlocked a vault of information about how genes move between bacteria and how DNA moves within the chromosome."

Meagher first worked last year with Klebsiella pneumoniae ATCC BAA-2146 (Kpn2146), the first U.S. isolate found to encode NDM-1. Along with E.coli, it was used to test an automatic sequencing library preparation platform for the RapTOR Grand Challenge, a Sandia project that developed techniques to allow discovery of pathogens in clinical samples.

"I've been interested in multi-drug-resistant organisms for some time. The NDM-1 drug resistance trait is spreading rapidly worldwide, so there is a great need for diagnostic tools," said Meagher. "This particular strain of Klebsiella pneumoniae is fascinating and terrifying because it's resistant to practically everything. Some of that you can explain on the basis on NDM-1, but it's also resistant to other classes of antibiotics that NDM-1 has no bearing on."

Unlocking Klebsiella pneumoniae

Assembling an entire genome is like putting together a puzzle. Klebsiella pneumoniae turned out to have one large chromosome and four plasmids, small DNA molecules physically separate from and able to replicate independently of the bacterial cell's chromosomal DNA. Plasmids often carry antibiotic resistant genes and other defense mechanisms.

The researchers discovered their Klebsiella pneumoniae bacteria encoded 34 separate enzymes of antibiotic resistance, as well as efflux pumps that move compounds out of cells, and mutations in chromosomal genes that are expected to confer resistance. They also identified several mechanisms that allow cells to mobilize resistance genes, both within a single cell and between cells.

"Each one of those genes has a story: how it got into this bacteria, where it has been, and how it has evolved," said Williams.

Necessity leads to development of new tools

Klebsiella pneumoniae uses established mechanisms to move genes, such as "jumping genes" known as transposons, and genomic islands, mobile DNA elements that enable horizontal gene transfer between organisms. However, the organism has so many tricks and weapons that the research team had to go beyond existing bioinformatics tools and develop new ways of identifying mechanisms of genetic movement.

Williams and Hudson detected circular forms of transposons in movement, which has never been shown this way, and discovered sites within the genome undergoing homologous recombination, another gene mobilization mechanism. By applying two existing bioinformatics methods for detecting genomic islands, they found a third class of islands that neither method alone could have detected.

"To some extent, every extra piece of DNA that a bacteria acquires comes at some cost, so the bacteria doesn't usually hang onto traits it doesn't need," said Hudson. "The further we dug down into the genome, the more stories we found about movement within the organism and from other organisms and the history of insults, like antibiotics, that it has faced. This particular bacteria is just getting nastier over time."

Applying findings to future work

The findings are being applied to a Laboratory Directed Research and Development project led by Sandia microbiologist Eric Carnes, who is examining alternative approaches for treating drug-resistant organisms. "Instead of traditional antibiotics, we use a sequence-based approach to silence expression of drug-resistant genes," said Meagher.

The researchers also are applying their understanding of Klebsiella pneumoniae's mechanisms of resistance and their new bioinformatics tools to developing diagnostic tools to detect bioengineering. Looking across 10 related but distinct strains of Klebsiella pneumoniae, they pinpointed regions that were new to their strain, and so indicate genetic movement.

"By studying the pattern of movement, we can better characterize a natural genomic island," said Hudson. "This leads down the path of what does an unnatural island look like, which is an indication of bioengineering. We hope to apply the knowledge we gained from sequencing Klebsiella pneumoniae to developing diagnostic tools that could detect bioengineering."

Journal Reference:

Corey M. Hudson, Zachary W. Bent, Robert J. Meagher, Kelly P. Williams.Resistance Determinants and Mobile Genetic Elements of an NDM-1-Encoding Klebsiella pneumoniae Strain. PLoS ONE, 2014; 9 (6): e99209 DOI:10.1371/journal.pone.0099209

Sandia National Laboratories. "Clues to superbug evolution: Microbiologists sequence entire genome of a Klebsiella pneumoniae strain." ScienceDaily. ScienceDaily, 23 September 2014.

Sandia National Laboratories’ researchers Kelly Williams, left, and Corey Hudson look at the mosaic pattern of one of the Klebsiella pneumoniae plasmids and discuss mechanisms that mobilize resistance genes.

Credit: Photo by Dino Vournas

[Click to enlarge image]

Water-quality trading can reduce river pollution: Market for waterquality credits would cut pollution at less cost

2014-09-23T18:44:00.001-04:00

Allowing polluters to buy, sell or trade water-quality credits could significantly reduce pollution in river basins and estuaries faster and at lower cost than requiring the facilities to meet compliance costs on their own, a new Duke University-led study finds.

The scale and type of the trading programs, though critical, may matter less than just getting them started.

"Our analysis shows that water-quality trading of any kind can significantly lower the costs of achieving Clean Water Act goals," said Martin W. Doyle, professor of river science and policy at Duke's Nicholas School of the Environment.

"All other things being equal, regulators should allow trading to occur at the river basin scale as an appropriate first step. Larger spatial scales may be needed later if abatement costs increase," said Doyle, who also serves as director of the water policy program at Duke's Nicholas Institute for Environmental Policy Solutions.

The new study was published this month in the journal Water Resources Research. It comes at a time when regulators are debating the optimal scales and types of trading programs to reduce water pollution in some of the nation's largest and most troubled watershed systems, including the Chesapeake Bay watershed, which spans 64,000 square miles in parts of six states.

In water-quality trading programs, facilities facing higher pollution control costs are allowed to meet their regulatory obligations by purchasing pollution reduction credits from other polluters in their trading market. The end result -- improved water quality -- is the same, but the time and money needed to achieve it is less.

New programs are often delayed because regulators want to get as many things right up front as they can. Concerns include how big or small a trading market should be, whether it should include interstate trading, and whether it should be based on one-for-one trades or trading ratios.

Getting these details right is vital, Doyle said, but it's also important not to let them bog down a program's launch.

"Our research very clearly shows that while achieving an optimal scale is best, any approach will yield gains over no trading at all," he said. "So the point is to allow trading."

To conduct their analysis, Doyle and his team developed a coupled hydrologic-economic model that measured the impacts of one-for-one trading and trading ratios among wastewater treatment plants in river basins draining into North Carolina's Albemarle-Pamlico Sound, the nation's second largest estuary. They assessed the pros and cons of each program type over the entire length of the basins, not just downriver or in the estuary. They also looked at how costs were affected when market scale was expanded from sub-basin to basin-wide, and then to a larger area that included adjacent basins extending into Virginia.

"As the markets got larger, facilities had more opportunities to find suitably sized trading partners who could help them reduce compliance costs," Doyle said. "But as we exceeded the basin scale, we reached a tipping point where risks increased so that pollution from many sources could end up in just a few places, creating pollution hotspots."

The study found only modest differences in the effectiveness of programs allowing one-for-one trading versus trading ratios. The optimal scales of markets remained the same under either scenario.

In addition to demonstrating that basin-wide trading is the optimal initial scale for many markets, the team's findings reinforce the need for interstate trading, Doyle said.

"Look at a map of the United States. If we are going to have water-quality trading here, we are going to have to allow interstate trading because of the geography of our states and river basins," he said. "Pollution doesn't start or stop at state borders."

Doyle is planning future studies to see if the same approach works for reducing non-point-source pollution from urban and agricultural runoff, which is a bigger problem in many river basins.

Journal Reference:

Martin W. Doyle, Lauren Patterson, Yanyou Chen, Kurt Schnier, Andrew J. Yates.Optimizing the Scale of Markets for Water Quality Trading. Water Resources Research, Sept. 11, 2014 DOI: 10.1002/2014WHR015395

Duke University. "Water-quality trading can reduce river pollution: Market for water quality credits would cut pollution at less cost." ScienceDaily. ScienceDaily, 23 September 2014. <www.sciencedaily.com/releases/2014/09/140923131446.htm>

Bacterial fibers critical to human, avian infection

2014-02-06T19:21:00.001-05:00

This illustration shows the bacterial expression of Escherichia coli common pilus (ECP) using fluorescence (in green) in biofilm (A) and in contact with cells (B). Both commensal and pathogenic E. coli strains produce ECP. In Avian pathogenic E. Coli (APEC) infections, ECP plays an important role in host cell recognition and biofilm formation. Credit: Arizona State University

In a new study conducted in Assistant Professor Melha Mellata's lab, at the Biodesign Institute at Arizona State University, lead author Alyssa K. Stacy and her colleagues examine one such bacterial adversary, Avian pathogenic Escherichia coli (APEC).

The research, conducted in collaboration with scientists at the University of Florida, Gainesville, appears in the current issue of the journal PLOS ONE.

The researchers targeted a specific group of threadlike fibers known as E. coli common pilus (ECP), which adorn bacterial cell surfaces. In the first study of its kind, they analyzed the way these structures contribute to APEC's ability to cause infection and form dense cell aggregates known as biofilms.

APEC infections are a serious threat to poultry, causing both systemic and localized infections, collectively known as colibacillosis. These afflictions cause significant economic losses to the poultry industry, due to the costs of treatment for infected birds, lowered rates of egg production, and mortality.

Further, APEC infections may pose a risk to humans, due to their zoonotic potential -- their ability to infect human hosts. A better understanding of infectious capacity (or virulence) and zoonotic potential are therefore essential for combatting these hazardous pathogens.

Stacy was an undergraduate student in Dr. Mellata's lab, and was partialy supported by funding from School of Life Sciences Undergraduate Research (SOLUR), ASU. She was joined by Biodesign researchers Natalie M. Mitchell, Jacob T. Maddux, and Roy Curtiss III (who directs the Institute's Center for Infectious Diseases and Vaccinology).

Avian Pathogenic E. coli (APEC) belong to a broad group of extraintestinal pathogenic E. coli (ExPEC) strains. Colibacillosis, caused by APEC in birds, leads to serious illness, often attacking the avian respiratory system, producing systemic or localized infections depending on the age and gender of bird, immunologic health and various environmental factors.

Because APEC and human ExPEC forms share important virulence characteristics, possible zoonotic transmission is a serious health concern. APEC may also provide a reservoir for virulence genes that may be acquired by human strains.

Many types of bacteria produce extracellular surface fibers like ECP, enabling them to adhere to one another as well as to various surfaces. But such fibers or pili perform other vital functions, particularly in the case of pathogenic bacteria. Pili, including those projecting from the surfaces of E. coli, are capable of recognizing specific host cell receptors during their initial phase of colonization.

Bacteria make further use of their pili to form cellular biofilms. Such bacterial aggregates are of clinical importance, as they provide reservoirs for pathogenic organisms to persist in the host and often display increased resistance to antibiotics.

E. coli common pilus (ECP) was originally identified in an ExPEC form known to cause neonatal meningitis in humans, but was later recognized as a component in all classes of E. coli -- both pathogenic and benign.

While E. coli bacteria exist primarily as beneficial residents of the human intestine, extraintestinal variants are responsible for diarrheal diseases like hemorrhagic colitis, as well as urinary tract infections, neonatal meningitis, sepsis, and pneumonia. The toll of such diseases -- particularly in the developing world -- is substantial, claiming some 2.5 million lives per year. Most of these victims are children.

The current study draws on examinations of ECP both in vitro and in vivo. The aim was to determine the prevalence of ECP among APEC strains and evaluate its contribution in the early stage of biofilm formation and host cell recognition. Additionally, the study assessed ECP's role in virulence in baby chicks.

The new research demonstrates -- for the first time -- the prevalence of ecpA, a gene coding for a major structural subunit of ECP in a majority APEC sequences examined. (The complex architecture of ECP fibers is composed of 6 distinct structural subunits.) With the aid of PCR methods, the group tested 167 APEC strains derived from chickens and turkeys afflicted with colibacillosis, 76 percent of which tested positive for ecpA, which was previousely associated with human pathogenic E. coli.

The authors stress that the results confirm that APEC and human pathogenic E. coli strains share virulence traits. They further speculate that ecpA may permit the persistence of E. coli bacteria in the intestine, where they exist in a non-threatening state, before migrating to alternate, extraintestinal sites, becoming pathogenic.

Environmental conditions, including low pH, low growth temperature and high acetate concentration have been shown to upregulate the expression of ECP in human E. coli strains that cause urinary tract infections, meningitis, and diarrheal diseases. In the current study, an APEC strain was found to adhere to human cervical cells in a manner similar to human ExPEC infections. Further, the results showed that adorning APEC with anti-ECP antibodies -- a process known as opsonization -- could significantly inhibit bacterial adherence. This finding suggests that ECP could be considered as a potential antigen for vaccines for both human and poultry infections.

The formation of biofilms is a common bacterial property, including in E. coli, where the adaptation increases survivability inside and outside of the host and provides an ideal environment for the exchange of genetic material. Bacteria forming biofilms frequently display antibiotic resistance and can be tenacious foes to combat medically. Deletion of ECP-related genes was shown to reduce biofilm production.

Finally, the study attempted to evaluate APEC virulence in baby chicks, using strains with deleted ECP genes. Results show a reduction in virulence. In fact, the potential for colonization among the ECP deletion strains was reduced, particularly in the bloodstream.

The new work demonstrates multiple roles for ECP in APEC, and thus presents a plausible target for future therapeutics aimed at these serious infections of both humans and animals.

"Our study has clearly shown that although the gene of ECP was found in a large number of APEC, these bacteria express this gene differently when they are in contact with cells or in biofilm," Mellata says. "Elucidating how the expression of some genes is turned on or off by different factors will help us understand how these bacteria cause disease."

Arizona State University. "Bacterial fibers critical to human, avian infection." ScienceDaily. www.sciencedaily.com/releases/2014/02/140206101111.htm (accessed February 6, 2014).

Early universe 'warmed up' later than previously believed: Research suggests a way to detect the earliest black holes

2014-02-06T18:42:00.001-05:00

New research suggests that black holes, formed from the first stars in our universe, heated the gas throughout space later than previously thought.

Credit: © procy_ab / Fotolia

A new study from Tel Aviv University reveals that black holes, formed from the first stars in our universe, heated the gas throughout space later than previously thought. They also imprinted a clear signature in radio waves which astronomers can now search for. The work is a major new finding about the origins of the universe.

"One of the exciting frontiers in astronomy is the era of the formation of the first stars," explains Prof. Rennan Barkana of TAU's School of Physics and Astronomy, an author of the study. "Since the universe was filled with hydrogen atoms at that time, the most promising method for observing the epoch of the first stars is by measuring the emission of hydrogen using radio waves."

The study, just published in the journal Nature, was co-authored by Dr. Anastasia Fialkov of TAU and the École Normale Supérieure in Paris and Dr. Eli Visbal of Columbia and Harvard Universities.

Cosmic archaeology

Astronomers explore our distant past, billions of years back in time. Unlike Earth-bound archaeologists, however, who can only study remnants of the past, astronomers can see the past directly. The light from distant objects takes a long time to reach Earth, and astronomers can see these objects as they were back when that light was emitted. This means that if astronomers look out far enough, they can see the first stars as they actually were in the early universe. Thus, the new finding that cosmic heating occurred later than previously thought means that observers do not have to search as far, and it will be easier to see this cosmic milestone.

Cosmic heating may offer a way to directly investigate the earliest black holes, since it was likely driven by star systems called "black-hole binaries." These are pairs of stars in which the larger star ended its life with a supernova explosion that left a black-hole remnant in its place. Gas from the companion star is pulled in towards the black hole, gets ripped apart in the strong gravity, and emits high-energy X-ray radiation. This radiation reaches large distances, and is believed to have re-heated the cosmic gas, after it had cooled down as a result of the original cosmic expansion. The discovery in the new research is the delay of this heating.

The cosmic radio show

"It was previously believed that the heating occurred very early," says Prof. Barkana, "but we discovered that this standard picture delicately depends on the precise energy with which the X-rays come out. Taking into account up-to-date observations of nearby black-hole binaries changes the expectations for the history of cosmic heating. It results in a new prediction of an early time (when the universe was only 400 million years old) at which the sky was uniformly filled with radio waves emitted by the hydrogen gas."

In order to detect the expected radio waves from hydrogen in the early universe, several large international groups have built and begun operating new arrays of radio telescopes. These arrays were designed under the assumption that cosmic heating occurred too early to see, so instead the arrays can only search for a later cosmic event, in which radiation from stars broke up the hydrogen atoms out in the space in-between galaxies. The new discovery overturns the common view and implies that these radio telescopes may also detect the tell-tale signs of cosmic heating by the earliest black holes.

Story Source:

The above story is based on materials provided by American Friends of Tel Aviv University. Note: Materials may be edited for content and length.

Reference:

Anastasia Fialkov, Rennan Barkana, Eli Visbal. The observable signature of late heating of the Universe during cosmic reionization. Nature, 2014; DOI: 10.1038/nature12999

American Friends of Tel Aviv University. "Early universe 'warmed up' later than previously believed: Research suggests a way to detect the earliest black holes." ScienceDaily. ScienceDaily, 5 February 2014. <www.sciencedaily.com/releases/2014/02/140205143802.htm>.

First live births with a novel simplified IVF procedure...

2014-02-06T18:37:00.001-05:00

A recent prospective study comparing conventional IVF with a novel simplified laboratory method of culturing embryos suggested that fertilization and implantation rates were similar for the simplified system when compared with those reported by conventional IVF programs. Sixteen healthy babies have already been born with this new method. According to the results of this study, IVF may be offered at a more reasonable price and made available to a larger part of the world population.

Click to enlarge

Results of a new study in which a simple, reduced cost IVF culture system was used to replace more expensive incubator systems demonstrated that new method does not alter the need for surgical egg retrieval and embryo transfer, laboratory staffing and egg or embryo freezing.

More than 5 million IVF babies have now been born worldwide, but because of high costs IVF is largely the preserve of developed countries and is only available or affordable for less than 10% of the world population. The success and sustainability of assisted reproductive technologies will depend to a large extent on the ability to optimize these techniques in terms of availability, affordability and effectiveness.

In developing countries the consequences of involuntary childlessness can create wide-ranging societal problems, especially for women. Because many families in developing countries depend entirely on children for economic survival, childlessness can often be viewed as a social and public-health issue and not only as a medical problem.

Published in Reproductive BioMedicine Online, American and Belgian researchers outline the first results of a prospective study performed in Genk, Belgium. They report the results of a study in which a simple, reduced cost IVF culture system was used to replace more expensive incubator systems. The new method does not alter the need for surgical egg retrieval and embryo transfer, laboratory staffing and egg or embryo freezing.

In a short prospective clinical trial, successful outcomes were obtained with the simplified method at levels that compare favorably with those reported by typical IVF programs in developed countries.

Sixteen healthy babies have now been born using the new method. It is expected that laboratory costs may be reduced, however the extent of this remains to be determined.

The simplified IVF method has the potential to open up a new era in the history of IVF and may not only change the accessibility of IVF in resource-poor countries, but also have implications for accessibility in developed countries too, where IVF is increasingly becoming available only to affluent couples. The trend in IVF has been to introduce new and complex instruments and tests. It is hoped that the new embryo culture method may change this philosophy.

This study is part of the Walking Egg Project, an international project that aims to raise awareness surrounding involuntary childlessness in resource-poor countries. The project also aims to make infertility care in all its aspects, including assisted reproductive technologies, available and accessible for a larger proportion of the world population in both developing and developed countries.

References:

Jonathan Van Blerkom, Willem Ombelet, Elke Klerkx, Mia Janssen, Nathalie Dhont, Geeta Nargund, Rudi Campo. First births with a simplified culture system for clinical IVF and embryo transfer. Reproductive BioMedicine Online, 2013; DOI: 10.1016/j.rbmo.2013.11.012

Willem Ombelet. Is global access to infertility care realistic? The Walking Egg Project. Reproductive BioMedicine Online, 2013; DOI: 10.1016/j.rbmo.2013.11.013

Elsevier. "First live births with a novel simplified IVF procedure." ScienceDaily. www.sciencedaily.com/releases/2014/02/140204074031.htm (accessed February 6, 2014)

RNA sequencing of 750-year-old barley virus sheds new light on the Crusades

2014-02-06T18:30:00.001-05:00

Dr Robin Allaby of the School of Life Sciences at the University of Warwick, who led the study, said: “It is important to know as much as we can about virus evolution as emerging infectious plant diseases are a growing threat to global food security, and of those viruses account for almost half.

Scientists have for the first time sequenced an ancient RNA genome -- of a barley virus once believed to be only 150 years old -- pushing its origin back at least 2,000 years and revealing how intense farming at the time of the Crusades contributed to its spread.

Researchers at the University of Warwick have detected and sequenced the RNA genome of Barley Stripe Mosaic Virus (BSMV) in a 750-year-old barley grain found at a site near the River Nile in modern-day Egypt. Their study is published in the journal Scientific Reports.

This new find challenges current beliefs about the age of the BSMV virus, which was first discovered in 1950 with the earliest record of symptoms just 100 years ago.

Although ancient DNA genomes have been sequenced before, ancient RNA genomes have not been as RNA breaks down more rapidly than DNA -- generally around 50 times as fast.

However in extremely dry conditions, such as those at the site in Qasr Ibrim in Lower Nubia where the barley was found, RNA can be better preserved and this has allowed the scientists to successfully sequence its genome.

Using the new medieval RNA to calibrate estimates of the rate of mutations, the researchers were able to trace the evolution of the Barley Stripe Mosaic Virus to a probable origin of around 2,000 years ago, but potentially much further back to the domestication of barley in the Near East around 11,000 years ago.

BSMV is transmitted through seed-to-seed contact so it is likely to originally have been transferred from the wild grass population to an early cultivated form of barley while the seeds were stored.

Dr Robin Allaby of the School of Life Sciences at the University of Warwick, who led the study, said: "It is important to know as much as we can about virus evolution as emerging infectious plant diseases are a growing threat to global food security, and of those viruses account for almost half.

"History tells us about the devastation caused by the emergence of disease from wild hosts in disparate countries, such as the Central American origin of the oomycete that led to the Irish potato famine.

"We need to build up an accurate picture of the evolution of different types of virus so we can make better decisions about policies on plant movement.

"The medieval RNA from Qasr Ibrim gives us a vital clue to unlock the real age of the Barley Stripe Mosaic Virus.

"It is very difficult to understand how a plant disease evolved by solely relying on recent samples, however this 750-year-old example of the virus allows us to more accurately estimate its evolution rates and date of origin.

"Without the Medieval RNA evidence, the virus appears to be much younger than it actually is, when in fact its origins go back thousands of years.

"It's possible that other viruses that similarly appear to be very recent may in fact have a more ancient origin."

The researchers believe that the Medieval BSMV genome came from a time of rapid expansion of the plant disease in the Near East and Europe.

This coincided with the tumult of the Crusades which saw the Christian lands of Europe take arms against the Muslim territories of the Near East with their sights set on the city of Jerusalem. The seventh Crusade of Louis IX in 1234 is the most closely aligned in date to the origin of the virus expansion.

The researchers believe the massive war effort could have caused the virus to spread, fuelled by an intensification of farming in order to feed the armies engaged in the campaign.

This made contact with cultivated barley and wild grass more likely, providing opportunities for the virus to 'jump' into the crop.

Genetic evidence also points to a split into an east and west BSMV lineage around the end of the 15th century, around 100 years after the Mongol Empire stabilised the Silk Road. It is likely that BSMV was transported to the east via trade routes such as the Silk Road in the late Medieval period.

In more recent history, the virus appears to have spread to the US from Europe around 120-150 years ago.

The research was supported by the research funding body BBSRC.

.

Journal Reference:

Oliver Smith, Alan Clapham, Pam Rose, Yuan Liu, Jun Wang, Robin G. Allaby. A complete ancient RNA genome: identification, reconstruction and evolutionary history of archaeological Barley Stripe Mosaic Virus.

Source: University of Warwick. "RNA sequencing of 750-year-old barley virus sheds new light on the Crusades." ScienceDaily. www.sciencedaily.com/releases/2014/02/140206111332.htm (accessed February 6, 2014).

Queen Bee's Honesty Is the Best Policy for Reproduction Signals

2013-11-13T21:21:00.000-05:00

Worker honey bees perform a "retinue response," in which they are attracted to the queen (marked with a number tag), surround her, lick her, and "smell" her with their antennae. This behavior allows the workers to pick up the queen pheromone and spread it throughout the colony. The queen pheromone provides "honest" information to the workers about her presence, mating status, and mating quality. (Credit: Bernardo Niño, Penn State)

Queen bees convey honest signals to worker bees about their reproductive status and quality, according to an international team of researchers, who say their findings may help to explain why honey bee populations are declining.

"We usually think of animals' chemical signals (called pheromones) as communication systems that convey only very simple sorts of information," said Christina Grozinger, professor of entomology and director of the Center for Pollinator Research, Penn State. "However, this study demonstrates that queen honey bees are conveying a lot of nuanced information through their pheromones.

"In addition, until now, no one knew if queen bees were manipulating workers into serving them or if they were providing valuable, honest information to workers. We have found that the information queens are conveying constitutes an honest message about their reproductive status and quality. The queens are 'telling' the workers that they are queens, whether or not they are mated and how well mated they are. In other words, whether or not they have mated with a lot of males."

Why do worker bees care if their queen is well mated? According to Elina Niño, postdoctoral fellow, Penn State, previous research has shown that colonies headed by more promiscuous queens -- those who mate with many males -- are more genetically diverse and, therefore, healthier, more productive and less likely to collapse.

"Beekeepers have been very worried about their queens, since they seem to not be lasting as long -- a few weeks or months instead of one or two years," said Niño. "We know that workers will replace their queens when they are not performing well. So if worker bees are able to detect poorly mated queens and take steps to remove them, that could be an explanation for the rapid rates of queen loss and turnover that beekeepers have been reporting."

The researchers, who represent Penn State, North Carolina State University and Tel Aviv University, describe how they assigned queen bees to a variety of treatment groups. They report their findings in today's (Nov. 13) issue of PLOS ONE.

In one group, they inseminated queens with a small volume of semen to mimic a poorly mated queen scenario. In a second group, the researchers inseminated queens with a large volume of semen to mimic a well-mated queen scenario. In a third and fourth group, they inseminated queens with low and high volumes of saline. A fifth group was an untreated control.

The researchers then dissected the queens, removing two glands that are known to produce pheromones -- the mandibular gland and the Dufour's gland. Next, the team extracted the glands' secretions and analyzed their chemical compositions using gas chromatography-mass spectrometry. Finally, the researchers presented the gland extracts to worker bees and observed the extent to which they were attracted to different extracts.

The team found that worker bees preferred pheromone extracts of queens that were inseminated with semen rather than saline. They also found that queens inseminated with higher volumes of semen or saline as opposed to those that were inseminated with low volumes of semen or saline were preferred by worker bees.

"These results suggest that queens are signaling detailed and honest information about their mating state and reproductive quality to workers, and workers are capable of adjusting their behavior accordingly," Niño said. "When workers replace failing queens, it is particularly damaging to beekeepers since it can take up to three weeks for the new queen to begin laying eggs and another three weeks for the new workers to emerge as adults. This reduces the workforce and therefore reduces honey production and even pollination efficiency."

The team also found that the mandibular gland and the Dufour's gland differ in their functions.

"The Dufour's gland seems to inform workers that queens have mated, while the mandibular gland seems to indicate the queen's mating quality," Niño said. "This also means that these glands are likely being regulated via different neurophysiological pathways."

According to Grozinger, in addition to signaling queen bee reproductive status and quality, queen bee pheromones regulate how fast workers mature and transition from taking care of developing larvae to foraging outside the hive.

"It is possible that changing the quality of the pheromone could disrupt this and other processes, which could have large-scale effects on colony organization and survival," she said.

Through funding from the Department of Agriculture, the researchers are beginning to examine the effects of viruses, pesticides and poor nutrition on queen pheromone quality to see if the queen also is providing workers with information about her health.

"The more we know about what affects the queen's health the better chance we will have of creating high-quality queens and disease-resistant stocks of honey bees," Niño said.

Journal Reference:
Elina L. Niño, Osnat Malka, Abraham Hefetz, David R. Tarpy, Christina M. Grozinger. Chemical Profiles of Two Pheromone Glands Are Differentially Regulated by Distinct Mating Factors in Honey Bee Queens (Apis mellifera L.). PLoS ONE, 2013; 8 (11): e78637 DOI: 10.1371/journal.pone.0078637

Penn State (2013, November 13). Queen bee's honesty is the best policy for reproduction signals. ScienceDaily. Retrieved November 13, 2013, from http://www.sciencedaily.com /releases/2013/11/131113182549.htm

Small Changes in Agricultural Practices Could Reduce Produce-Borne Illness

2013-11-13T21:10:00.001-05:00

Researchers from Cornell University have identified some agricultural management practices in the field that can either boost or reduce the risk of contamination in produce from two major foodborne pathogens: salmonella, the biggest single killer among the foodborne microbes, and Listeria monocytogenes. Their findings are published ahead of print in the journal Applied and Environmental Microbiology.

"This is going to help make produce safer," says Laura Strawn, a researcher on the study. "We could significantly reduce risk of contamination through changes that occur a few days before the harvest."

Many of the risk factors were influenced by when they were applied to fields which suggests that adjustments to current practices may reduce the potential for contamination with minimal cost to growers, says Strawn.

Foodborne illness sickens an estimated 9.4 million, and kills around 1,300 annually in the US, according to the Centers for Disease Control and Prevention. Produce accounts for nearly half the illnesses, and 23 percent of the deaths.

"The research is the first to use field collected data to show the association between certain management practices and an increased or decreased likelihood of salmonella and L. monocytogenes," says Strawn.

For salmonella, manure application within the year prior to the researchers' sampling boosted the odds of a contaminated field, while the presence of a buffer zone between the fields and potential pathogen reservoirs such as livestock operations or waterways was protective.

Irrigation within three days before sample collection raised the risk of listeria contamination six-fold. Soil cultivation within the week before sampling also increased the chances of contamination.

"These findings will assist growers in evaluating their current on-farm food safety plans (e.g. "Good Agricultural Practices"), implementing preventive controls that reduce the risk of pre-harvest contamination, and making more informed decisions related to field practices prior to harvest," says Strawn. "Small changes in how produce is grown and managed could result in a large reduction of food safety risks."

Story Source:

The above story is based on materials provided by American Society for Microbiology .

Journal Reference:

Strawn et al. Risk Factors Associated with Salmonella and Listeria monocytogenes Contamination of Produce Fields. Applied and Environmental Microbiology, December 2013

American Society for Microbiology (2013, October 21). Small changes in agricultural practices could reduce produce-borne illness. ScienceDaily. Retrieved November 13, 2013, from http://www.sciencedaily.com /releases/2013/10/131021155812.htm