Culture

WASHINGTON, June 20, 2019 -- After walking on the moon, astronauts hopped back into their lunar lander, bringing the heavenly body's dust along with them on their spacesuits. They were surprised, and perplexed, to find that it smelled like spent gunpowder. This week on Reactions, learn why moon dust might smell like the aftermath of a Civil War reenactment: https://youtu.be/iQod_oYnFTc.

A study from the Institute for Research in Biomedicine (IRB Barcelona) has published a study in the journal Nature Catalysis that describes the reaction mechanism used by the DNAzyme 9DB1, the first structurally available catalyser formed by DNA.

Until recently, it was widely assumed that DNA served to store genetic information in a stable and irreversible manner. However, in the last ten years, the discovery of the epigenetic code and the finding that nucleic acids can also catalyse certain reactions have changed this vision.

The team headed by Modesto Orozco, head of the Molecular Modelling and Bioinformatics Lab at IRB Barcelona, found that this DNAzyme catalyses RNA ligation through a similar mechanism to that used by natural enzymes.

The conclusion drawn by the study may lead to improvements in current catalysers and in the design of novel biocatalysers formed by DNA. Indeed, given that DNAzymes can carry out a variety of reactions on messenger RNA and can trigger the silencing of genes, they are being developed for diagnostic and biomedical applications.

"The role of DNAzymes as catalysers is of great interest since they are easier to synthesise than proteins and RNA molecules, as well as being more stable and less expensive. However, to date, the catalytic mechanism used by DNAzymes was unknown, as were the differences between catalysers made of DNA and RNA or the protein enzymes," says Orozco, senior professor at the University of Barcelona.

The study published by the IRB Barcelona team aimed to unravel the details of the catalytic mechanism of DNAzymes. To this end, Juan Aranda and Montserrat Terrazas, postdoctoral fellows at IRB Barcelona and first authors of the work, studied DNAzyme 9DB1 at the atomic level using computational simulations and then experimentally validated their findings.

The various computational techniques, ranging from molecular dynamics to the combined use of quantum mechanics and classical mechanics, included in the study have allowed the characterisation of the catalytic state of 9DB1. Using these approaches, the researchers have achieved the first atomic description of the reaction mechanism of a DNAzyme and have characterised the most important interaction in the catalysis and in the transition state of the reaction.

They have experimentally synthesised in vitro variants of 9DB1 to confirm the mechanism that was predicted through the computational approach. The reaction mechanism used by the DNAzyme resembles that of polymerases, which use two divalent cations.

Finally, the scientists have analysed the differences and similarities between the catalytic capacity of DNA, RNA and polymerases. Such atomic information is expected to lead to the design of more efficient DNAzymes.

Adding vanilla to sweetened milk makes consumers think the beverage is sweeter, allowing the amount of added sugar to be reduced, according to Penn State researchers, who will use the concept to develop a reduced-sugar chocolate milk for the National School Lunch Program.

"We are utilizing a learned association between an odor and a taste that will allow us to reduce the added sugar content," said Helene Hopfer, assistant professor of food science. "Reducing added sugar in products, just like reducing fat and salt, is the holy grail of food science."

The idea that congruent or harmonious odors enhance certain tastes is not new, explained Hopfer, whose research group in the College of Agricultural Sciences has been experimenting with these "cross-modal interactions" in food since she came to Penn State three years ago. Her goal is to see them actually incorporated into foods.

In a blind taste test that provided new insights into taste enhancement by an aroma, participants -- who did not know vanilla had been added to the milk -- consistently indicated that samples with vanilla were significantly sweeter than their added sugar concentrations could explain.

The subjects' responses indicate that with the addition of vanilla, the added sugar content in flavored milk could potentially be reduced by 20 to 50 percent, suggested lead researcher Gloria Wang, and people should not be able to perceive the beverage as less sweet.

"We maintain the sweetness perception by having this congruent odor -- this learned, associated odor -- basically trick the brain into thinking that there is still enough sweetness there," she said. "Based on our results, taste-aroma interaction is a robust effect."

Wang, now an associate scientist in product development with Leprino Foods Co. in Colorado, conducted the research at Penn State as part of her master's degree thesis in food science. She tested not only congruent taste-aroma combinations but incongruent combinations as well. It turned out that even a beef odor in milk slightly enhanced sweetness for study participants.

Given widespread concerns about sugar intake and health, manufacturers are reformulating their products to help address consumer demand, Wang noted. She believes the findings of the research, recently published in Food Quality and Preference, offer them a workable option to reduce added sugar in their products and retain the sweetness consumers demand.

The study was novel because it did not ask participants to rate individual attributes of the milk such as sweetness, intensity of vanilla odor or milk taste. Instead, participants took a more holistic approach and simply selected the best match for the vanilla milk from four differently sweetened milk choices.

Later this summer, Hopfer's lab in the Department of Food Science will start working on a two-year project, funded by the National Dairy Council, aimed at developing a reduced-sugar chocolate milk for the National School Lunch Program. The effort, based on the recent research using the synergistic actions between vanilla and sugar to reduce the added sugar content, will be a challenge because of the inherent bitterness of cocoa.

"The amount of sugar in chocolate milk is quite high because cocoa is very bitter, so you need some sugar to decrease the bitterness of the cocoa and then more to make it sweet," Hopfer said. "We are hoping to utilize what we found with odors to reduce the added sugar content by experimenting to find the sweet spot between cocoa powder, sugar content and vanilla flavor. We know that if it isn't sweet, children won't drink it."

Secured in place in a virtual-reality-equipped chamber, frustrated zebrafish just didn't want to swim anymore.

They had been "swimming" along fine, until the virtual reality system removed visual feedback associated with movement. To the fish, it appeared as if they were drifting backward, regardless of how hard they stroked.

First, the fish thrashed harder. Then, they simply gave up, says neuroscientist Misha Ahrens, a group leader at the Howard Hughes Medical Institute's Janelia Research Campus. "Giving up is a very important thing for animals to be able to do," he says. Without the ability to stop a behavior that's not working, animals would needlessly deplete their energy.

Ahrens and his team at Janelia wanted to identify the neurons responsible for the decision to quit. The researchers watched the zebrafish's brain activity patterns as they struggled. But the clearest signal wasn't coming from neurons. The cells that sprang into action just before the zebrafish called it quits were actually glia, long thought to play a supporting role in the brain.

The find, reported June 20, 2019, in the journal Cell, is clear evidence that cells other than neurons can perform computations that influence behavior - a discovery so surprising that the team took pains to verify their work, Ahrens says.

"We were excited and also very skeptical," he says. "We challenged ourselves to try and disprove it."

More than glue

Until about two decades ago, scientists thought glia (from the Greek for "glue") just provided support and insulation for neurons. But recent research has begun to uncover new roles for glia in processing. Now, Ahrens, Janelia Research Scientist Yu Mu, and their colleagues - Davis Bennett, Mikail Rubinov and others - have shown that, in zebrafish, one type of glial cell can calculate when an effort is futile.

"The original hope was that we would find the neurons that drive this 'giving-up' behavior," Ahrens says.

A whole-brain imaging technique previously developed at Janelia let the researchers look at all of a fish's brain cells, both neurons and glia, while it tried to swim. Then, the team compared the different cells' impact on behavior.

But surprisingly, the team had trouble identifying specific neurons that clearly impacted swimming behavior. Glia were a different story, Mu says. Certain glia, called radial astrocytes, amped up their activity in one part of the brain when the animals stopped trying to swim.

Neurons weren't completely out of the loop: each time a movement attempt failed, certain neurons revved the astrocytes up, until at last they crossed a threshold and sent the quit command. That command went out to a different set of neurons, which then suppressed swimming.

"You could think of the astrocytes as a counter for how many swim bouts have failed," says Mu. It's not a simple job: To tell the fish when to give up, the glia must monitor movement attempts, note repeated failures, and then send the "quit" message to the body.

Control astrocytes, change behavior

To verify the astrocytes' role, the researchers first used a laser to kill only the ones that consistently turned on when the fish gave up. In fact, the team found, fish who lacked those cells continued struggling to swim much longer than the fish whose astrocytes remained.

Next, the team created fish with astrocytes the team could control. Switch on the astrocytes, and the fish stop swimming, the team found, even when the visual environment wasn't messing with them. While normal fish rarely pause, fish with overactive astrocytes spent over half their time languishing in defeat. Taken together, these experiments confirmed that radial astrocytes indeed control the decision to stop swimming, Ahrens says.

One next step for the group will be studying exactly how the astrocytes communicate with neurons. Astrocytes can, for example, release chemical messengers that affect neuron behavior, Mu says. "Astrocytes are like a swiss army knife." Mu wants to identify which of their many tools they deploy to halt unproductive struggle.

University of Alberta researchers have added a new genetic marker to the breast cancer map, helping to expand the list of genetic mutations clinicians can watch for in cancer screenings.

The genetic marker--called rs1429142--was found to confer a higher risk of breast cancer in Caucasian women carrying the genetic variation compared to women without the variation. In premenopausal women, that risk reached as high as 40 per cent. The ability to identify those genes and their variants (called alleles) can be vital to early detection and life-saving treatment.

"This is important because the more we are able to create a complete picture of all the genes and all the variations and mutations that contribute to breast cancer, the closer we get to developing a genetic screen for breast cancer on a population level," said Sambasivarao Damaraju, a professor at the U of A's Department of Laboratory Medicine & Pathology and a member of the Cancer Research Institute of Northern Alberta. "If we can identify women at risk before they are diagnosed, and as long as we have the resources to mitigate that risk through preventative approaches, we can reduce the overall burden of breast cancer risk in a population."

Though the study primarily focused on genetic causes of breast cancer in Caucasian women, Damaraju's team went on to validate their findings in women of Chinese and African descent to explore the impact demographics may have on cancer risk.

Breast cancer is the most common cancer in women, with an estimated one out of every eight women expected to develop it in their lifetimes. While environmental factors like smoking, diet or lack of physical activity can lead to cancer, a person's genes also contribute to the risk of getting the disease.

"One of the real benefits of this research is that it brings a lot of focus to premenopausal breast cancer, which otherwise wasn't thought much about," said Mahalakshmi Kumaran, Damaraju's graduate student and first author on the paper.

The study, published in the International Journal of Cancer, is the first of its kind to examine breast cancer risk in Caucasian women divided into premenopausal and postmenopausal groupings. Because the majority of breast cancers are diagnosed in women over the age of 55, most genetic association studies focus on postmenopausal women. However, inherited forms of cancers, typically related to genetic mutations, are more likely to be more aggressive and be diagnosed earlier in life.

The researchers examined more than 9,000 women from Alberta for the study, utilizing samples from patients diagnosed with breast cancer and unaffected healthy controls from the Alberta Cancer Research Biobank and The Alberta's Tomorrow Project, respectively.

The DNA isolated from the participants' blood provided clues to specific chromosomes that showed links to breast cancer risk. Using those clues, the team began to zero in on the specific regions of the chromosome to locate genetic variations across samples. They noticed that rs1429142 showed a consistent association with breast cancer risk in multiple tests. When the data was analyzed based on menopausal status, the risk was shown to be significantly higher for premenopausal women.

After confirming the link between the genetic variant and breast cancer, the team then took the extra step of zooming in the genomic region to identify the specific location of the gene on the chromosome and marking it for future researchers.

"Finding this genetic marker is like starting with a high-resolution Google map of the world, and then slowly zooming in to the image of your house," Damaraju said. "It is valuable to do because now we have essentially planted a road sign on the chromosome that can help future researchers to carry out further in-depth studies."

Using international data from other genetic studies of breast cancer, and contributions from Vanderbilt University and St Jude Children's Research Hospital investigators from Tennessee, the team was also able to validate their findings in women of Chinese and African descent. They found that women of African descent were at a particularly high risk of premenopausal breast cancer as a result of the variant gene. This underlined the idea that genetic ancestry plays an important role in cancer risk.

While the study focused primarily on the genetic variation present on a single chromosome, Damaraju said they also found promising leads for identifying more cancer-related genetic markers on other chromosomes as well. In the future, he hopes to see his research contribute to a more precise method of treating breast cancer by tailoring therapies to the specific needs of the patient.

"My focus for the last 20 years has been to build a pipeline from genetic research to benefit the patient," he said. "We identify the genetic predispositions and focus on developing population-related risk models to enable potential screening of populations and eventually possible interventions."

Having aspirations helps us navigate life in a meaningful and fulfilling way, but it can also cause psychological distress when hopes are left unfulfilled.

New Edith Cowan University (ECU) research has found that it's not failing to make progress toward our 'ideal-self' that is problematic but rather the tendency to focus on that lack of progress in a negative way that leads to psychological distress.

In other words, it pays to be kind to yourself, say the key researchers.

The study, led by Associate Professor Joanne Dickson from ECU's School of Arts and Humanities, explored whether 'ideal-self' and 'actual-self' discrepancies were associated with depressive and anxious symptoms.

It also considered whether 'rumination', or excessive negative thinking, played a role in these relationships.

Professor Dickson said there are two key 'self-guides' that typically motivate us and provide standards for self-evaluation: the 'ideal-self' and the 'ought-self'.

"The 'ideal-self' is the person we ideally want to be - our hopes and aspirations. The 'ought self' is who we believe we ought to be - our duties, obligations, and responsibilities," she said.

"Our findings showed that perceiving one's hopes and wishes as unfulfilled and the loss of desired positive outcomes increases emotional vulnerability and psychological distress.

"Whereas actual-ought self-discrepancies were associated with anxiety (but not depression)."

The role of excessive negative thinking

Professor Dickson said a novel finding was the role of 'rumination', the tendency to engage in repetitive negative thinking.

"It's not failing to make progress toward our 'ideal-self' that is necessarily problematic but rather the tendency to repetitively think about this lack of progress that represents a significant vulnerability that, in turn, leads to increased psychological distress," she said.

In contrast, lack of progress in relation to our 'ought self' (ie duties, responsibilities, obligations) directly increased anxiety (but not depression), and this was not facilitated via repetitive thinking.

"It may be that fulfilling obligations, duties and responsibilities is more pressing or urgent than the pursuit of hopes and the more immediate negative consequences of not fulfilling these 'ought to' obligations may mean there is less time to engage in reflective contemplation," Professor Dickson said.

Advice for minimising psychological distress

Professor Dickson said self-guides as standards that we aspire to are beneficial in giving a sense of purpose and direction in life and promoting wellbeing, even if we don't always reach them, but turning the focus toward negative self-evaluation and self-criticism is counter-productive.

"Reflecting on and at times modifying our self-guides may be helpful, particularly if we are caught in a spiral of negative self-evaluation that is accompanied by a constant sense of failing to meet overly high standards.

"We need to be kind to ourselves and keep our self-guides in perspective," she said.

Athens, Ga. - For the first time, researchers in the University of Georgia's Regenerative Bioscience Center have used an imaging method normally reserved for humans to analyze brain activity in live agricultural swine models, and they have discovered that pig brains are even better platforms than previously thought for the study of human neurological conditions such as Alzheimer's and Parkinson's.

One immediate potential application is in the study and diagnosis of CTE, a progressive brain disease caused by a series of blunt trauma usually seen in military veterans and NFL football players. Currently CTE can be diagnosed only through an autopsy. The new study strongly suggests that a translational swine model for mapping functional brain connectivity is a promising approach to determine biomarkers or brain signatures that lead to CTE. Using this type of data, doctors would have the opportunity to diagnose CTE while a veteran or athlete is still alive.

By using resting-state functional magnetic resonance imaging (rs-fMRI), the researchers demonstrated functional connectivity in sensorimotor regions of the swine brain that parallels to that of the human brain. These regions include those where all our perceptions, feelings, movements and memories are encoded. The similarities of these functional networks, as published in the journal Brain Connectivity, set the stage for targeted clinical applications in the treatment and prevention of neurological disorders.

Franklin West, associate professor of animal and dairy science in College of Agricultural and Environmental Sciences, and his RBC collaborator, Qun Zhao, drew comparisons between sensory and cognitive relevance found in swine and those previously established in humans.

"Most of the models to-date deal with structural comparisons," said Zhao, associate professor of physics in the Franklin College of Arts and Sciences. "Our model goes beyond brain mass and allows us to address questions related to brain connectivity and memory function. Without a functional map of the brain it's hard to tell what parts of the brain are talking to each other."

Previous research has shown that shape and exact location of brain regions interact strongly with the modeling of brain connectivity. For years, researchers have posited that the shape and size of a swine brain bears physiological and anatomical similarities to the human brain, and therefore swine are considered a good animal model for neurological disease. However, according to the RBC team, scientists have not yet developed a unique model that captures functional connectivity or details the wiring diagram of the brain.

Neuroimaging typically helps researchers identify which regions of the brain activate when a person carries out a task; such as the simple task of starting a car. In order to turn on your car, you first have to look, then find, where to insert the key, as your brain takes visual cues and stimulates different parts of your arm to complete the action. Each part of your arm activates a different part of the brain in the act of inserting the key. If there's any interruption in the connections, those functions don't happen.

Those interrupted connections play a role in neurological disorders, such as Alzheimer's disease, Parkinson's disease, chronic traumatic encephalopathy (CTE) and autism. With any of these disorders, the RBC collaborators can now model a 360-degree view of which parts of the brain are no longer talking to each other and which centers in the brain are being reactivated and reconnected.

"What this new model allows and has never been done before," West said, "is for researchers to ask more refined questions about how the brain talks to itself, functions and coordinates action."

"What we tend to say is the brain is a black box and we don't know how it works," said West. "This study is a game changer. It gives us a light to shine inside the box."

Bottom Line: A substantial proportion of U.S. adults reported recently having an eye exam in this online survey study that included 2,013 adults ages 50 to 80. About 82% of those surveyed reported an eye exam in the past two years. Reasons for not getting an exam included not having eye problems, cost or lack of insurance. A limitation of the study is that adults with vision impairment may have been less likely to participate because the survey was administered online.

Authors: Joshua R. Ehrlich, M.D., M.P.H., University of Michigan, Ann Arbor, and coauthors

(doi:10.1001/jamaophthalmol.2019.1927)

Editor's Note: The article includes conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.

University of Cincinnati biologist George Uetz long suspected the extravagant courtship dance of wolf spiders made them an easy mark for birds and other predators.

But it was only when he and colleague Dave Clark from Alma College teamed up with former University of Minnesota researcher Tricia Rubi and her captive colony of blue jays that he could prove it.

For a study published in May in the journal Behavioural Processes, Rubi trained a captive colony of blue jays to peck at buttons to indicate whether or not they saw wolf spiders (Schizocosa ocreata) on video screens.

Clark made videos superimposing images of courting, walking and stationary male spiders on a leaf litter background. Rubi presented the videos to blue jays on a flat display screen on the ground.

When viewed from above, the brindled black and brown spiders disappear amid the dead leaves.

The jays had trouble finding spiders that stayed motionless in the videos. This confirmed the adaptive value of the anti-predator "freeze" behavior.

The jays had less trouble seeing spiders that walked in the video. And the jays were especially quick to find male spiders engaged in ritual courtship behavior, in which they wave their furry forelegs in the air like overzealous orchestra conductors.

"By courting the way they do, they are clearly putting themselves at risk of bird predation," UC's Uetz said.

His lab studies the complementary methods spiders employ to communicate with each other, called multimodal communication. Female spiders leave a pheromone trail behind them in their silk and when they rub their abdomens on the ground, Uetz said.

And when male spiders come into visual range, they bounce and rattle their legs on the leaf litter to create vibrations that can travel some considerable distance to the legs of potential mates. The males also wave their front legs in a unique pattern to captivate females.

The males of the species have especially furry front legs that look like black woolen leg warmers. The combination of thick fur and vigorous dancing are indicators that the male is fit and healthy, Uetz said.

"The displays and the decorations show off male quality," Uetz said. "The males that display vigorous courtship and robust leg tufts are showing off their immune competence and overall health. They, in turn, will have sons that have those qualities."

That is, if they live so long. Many birds, including blue jays, find spiders to be tasty. And a chemical called taurine found in spiders is especially important for the neurological development of baby birds, he said.?

Spiders instinctively fear predatory birds. In previous studies, Uetz, Clark and UC student Anne Lohrey determined that wolf spiders would freeze in place when they detected the sharp, loud calls of blue jays, cardinals and other insect-eating birds. By comparison, they ignored the calls of seed-eating birds such as mourning doves along with background forest noises such as the creak of katydids.

"They clearly recognized these birds as some kind of threat," Uetz said. "Robins will hunt them on the ground. Lots of other birds do, too. Turkeys will snap them up."

When Uetz proposed a spider experiment, Rubi said it wasn't hard to train her colony of blue jays. The jays quickly learned to peck at different buttons when they either observed a spider or didn't see one on a video screen.

"Birds are super visual. They have excellent color vision and good visual acuity. It's not surprising they would have no trouble seeing spiders in motion," she said.

Rubi now studies genetic evolution at the University of Victoria in British Columbia.

If natural selection means the most avid courting spiders are also most likely to get eaten, why does this behavior persist across generations? Wouldn't meeker spiders survive to pass along their genes?

Rubi said the explanation lies in another selective force.

"Natural selection is selection for survival, which would lead to spiders that are less conspicuous to predators," she said. "But sexual selection is driven by females. And they select for a more conspicuous display."

In genetic terms, Rubi said, fitness is measured in the number of healthy offspring produced. So while staying alive by minimizing risk is a good strategy for the individual, it's not a viable strategy for the species.

"The longest-lived male can still have a fitness of 'zero' if he never mates," Rubi said. "So there appears to be a trade-off between being safe and being sexy. That balance is what shapes these courtship displays."

Uetz said female wolf spiders can be very choosy about the qualities they value in a mate.

"The tufts on their forelegs are very important. Their size and symmetry play a big role," he said. "They're so tiny and have brains the size of a poppy seed. You wouldn't think they could discriminate, but they do."

And at least for successful male wolf spiders living in a hostile world, this means love wins over fear.

The total solar eclipse's swath across Wyoming and the United States in August 2017 provided an opportunity for scientists to study a variety of celestial and earthly phenomena, from learning more about the sun's corona to the behavior of animals and plants.

University of Wyoming botany and hydrology doctoral student Daniel Beverly used the eclipse to examine the impact of the moon's shadow on an iconic plant species of Wyoming and the Intermountain West: big sagebrush. He found that the short period of darkness caused a significant reduction in photosynthesis and transpiration in the desert shrub, but not quite to the levels of nighttime.

Additionally, the circadian rhythm -- the response to the internal clock common to nearly all organisms including humans -- was interrupted by the sudden changes in sunlight beyond typical cloud cover.

"The reduced temperature and lack of sunshine shocked the circadian clock of big sagebrush, triggering a response far beyond what happens when clouds block sunlight," says Beverly, whose research appears today (Thursday) in the journal Scientific Reports. "However, the duration of eclipse totality was not sufficient to bring the plants completely to their nighttime state."

Scientists have extensively studied the response of animals to total solar eclipses. Those findings have been mixed, with birds, bees and spiders behaving just as they do at dusk, while no behavioral change was observed in animals such as dairy cattle and captive chimpanzees. On the other hand, very little is known about plant responses to eclipses, either on the small scale or across broad ecosystems. Beverly's study -- which involved fellow UW scientists in the Department of Botany, the Program in Ecology and the Wyoming Geographic Information Science Center -- offers some of the most detailed information about individual plant response and potential broad ecosystem impacts ever reported.

Beverly's fieldwork took place at a site about 50 miles southeast of Yellowstone National Park, which was within the eclipse's path of totality Aug. 21, 2017. That area is dominated by mountain big sagebrush. The site experienced 2 minutes, 18 seconds of eclipse totality, with the total duration of partial and total solar eclipse reaching 2 hours, 45 minutes, 36 seconds.

Devices deployed during the study included a micrometeorological tower to record the sun's radiation and changes in temperature; an infrared gas analyzer to measure photosynthesis; and fluorometers to measure leaf response to changing light conditions. During the short duration of near darkness, they found significant reductions in transpiration -- evaporation of water from sagebrush leaves -- as well as photosynthesis, the transformation of light energy into chemical energy that converts carbon dioxide and water into sugar and oxygen.

In addition to documenting the response of specific sagebrush plants to the eclipse, Beverly and his colleagues used those results to estimate the eclipse's impact on sagebrush-dominated areas within the path of totality. They calculated a 14 percent reduction of carbon being converted in Western big sagebrush ecosystems that one day.

"Despite its relatively short duration, the eclipse caused a significant reduction in estimated daily carbon uptake for Aug. 21, 2017, in big sagebrush ecosystems," Beverly says. "This information gives us a more comprehensive understanding of plant physiological responses to sudden changes in light, temperature and humidity that the internal clock fails to predict."

A bacterial pathogen that typically multiplies outside of host cells can enter and induce the destruction of cells called macrophages, according to a study published June 20 in the open-access journal PLOS Pathogens by Anne-Béatrice Blanc-Potard of the Université de Montpellier in France, and colleagues.

Pathogenic bacteria are commonly classified as intracellular or extracellular pathogens. Intracellular bacterial pathogens can replicate within host cells, including macrophages, which ingest and kill microorganisms in a process called phagocytosis. By contrast, extracellular pathogens such as Pseudomonas aeruginosa multiply outside of cells. However, recent data have shown that several extracellular pathogens can enter host cells. For example, P. aeruginosa has been reported to be engulfed by macrophages in animal models.

In the new study, Blanc-Potard and her colleagues visualized the fate of P. aeruginosa within macrophages. P. aeruginosa first resided in vesicles called phagosomes and subsequently could be detected in the cytoplasm, indicating that the pathogen had escaped degradation within the phagosomes. The intracellular bacteria could eventually induce cell lysis - the disintegration of a cell through membrane rupture. Two bacterial molecules, MgtC and OprF, recently identified to be important for the survival of P. aeruginosa in macrophages, were found to activate intracellular production of type III secretion system (T3SS), which in turn was found to be involved in bacterial escape from the phagosome as well as in cell lysis caused by the bacteria. According to the authors, the transient stage in which P. aeruginosa resides inside of macrophages could contribute to bacterial dissemination during infection.

The authors add, "While the role of macrophages is to ingest and kill microorganisms, the pathogenic bacterium Pseudomonas aeruginosa can induce cell lysis when it insides inside macrophages. The weapons used by internalized bacteria to lyse the macrophage are decrypted."

After a prolonged decline, global hunger is on the rise--affecting more than 820 million individuals in 2017. Additionally, more than 2 billion people suffer from "hidden hunger," which occurs when individuals eat foods that don't provide the nutrients they need to lead healthy, productive lives. Children who suffer from hidden hunger have more difficulty developing to their full mental and physical potential.

Hidden hunger is more prevalent in developing countries that rely heavily on staple crops like wheat, maize, and rice. These populations often do not have access to nutrient-rich foods, such as fruits, vegetables, and fish, and tend to suffer from vitamin A and zinc deficiencies. Vitamin A deficiencies can lead to vision-related disorders, such as corneal scarring and blindness, while zinc deficiencies increase the risk of diarrheal diseases, pneumonia, malaria, and even mortality.

Global demand for staple crops like maize, wheat, and rice is on the rise--making these crops ideal targets for improving nutrition through biofortification. Biofortification is the process of developing micronutrient-dense staple crops by combining traditional breeding practices with modern biotechnology.

Biofortification crop systems are highly sustainable one-time investments--the varieties developed and released will continue to grow annually, even without government attention or external funding, and breeding for higher levels of vitamin A and zinc does not penalize yield. There are currently 290 varieties of 12 biofortified crops, including rice, wheat, maize, that target the low-income households who rely on these staple crops and may suffer from hidden hunger.

"Maize and wheat are excellent targets for biofortification because they are widely cultivated, have wide agroecosystem coverage, are important in diets and trade, have useful native genetic variation for improving micronutrient density in the grain, and have a long history as subjects of breeding and genetic research," according to the authors of "Improving Nutrition through Biofortification: Preharvest and Postharvest Technologies," published in Cereal Foods World.

Organizations such as the International Maize and Wheat Improvement Center (CIMMYT), HarvestPlus, and the International Institute of Tropical Agriculture have worked to develop provitamin A-enriched maize varieties and zinc-enriched maize varieties, which have been released in South America and Africa. These organizations have also worked on enhancing levels of iron and zinc in wheat grain, releasing six biofortified wheat varieties in Pakistan and India in recent years.

Nutritional studies have found these biofortified varieties to be effective. A study in India found that young children who ate zinc-biofortified wheat experienced 17% fewer days with pneumonia and 39% fewer days vomiting than those children who ate conventional wheat products. Provitamin A-biofortified maize is a proven source of vitamin A. Additional studies are likely to reveal more positive effects of biofortified staple crops on nutrition.

Biofortification is one way to address hidden hunger, but it is not without challenges. According to the Cereal Foods World article, "To realize their full potential, biofortified maize and wheat varieties must be integrated as a core products in research, policy, and food value chains for these crops, which implies that all participants in the value chain, particularly farmers and consumers, must be convinced of their value."

Horseshoe crabs that have undergone biomedical bleeding tend to reside in deeper water and approach mating beaches less often, according to a new study published in The Biological Bulletin. In "Effects of the Biomedical Bleeding Process on the Behavior of the American Horseshoe Crab, Limulus polyphemus in Its Natural Habitat," Meghan Owings and her colleagues report the results of an investigation of the behavioral and physiological effects that the bleeding process has on horseshoe crabs that are released back into their natural environment. The findings suggest biomedical bleeding may impact the reproductive output of female horseshoe crabs during the season in which they were bled.

Horseshoe crabs are harvested by the biomedical industry in order to create Limulus amebocyte lysate (LAL), which is used to test medical devices and pharmaceutical drugs for endotoxins. During the process, around 30 percent of a crab's blood is extracted before it is returned to its natural environment.

Owings' study is one of the first to examine the behavioral impacts that the bleeding process has on the horseshoe crabs once they are returned to the wild. "With the growing demand for LAL as the global population expands, medical advancements improve, and medical needs increase, it is critical to understand the consequences of the biomedical bleeding industry on horseshoe crabs' fitness and population dynamics," Owings writes.

Owings and her coauthors retrieved 28 horseshoe crabs from a spawning site in the Great Bay Estuary in New Hampshire. Half of the crabs were randomly selected to undergo the bleeding process and then all of them, both bled and controls, were fitted with acoustic transmitters and released where they had been captured. The transmitters were used to monitor the horseshoe crabs' movements, depth, and times when they were active. Data from the transmitters were logged by an array of acoustic receivers that were set up throughout the estuary.

All 28 horseshoe crabs were successfully tracked in the Great Bay Estuary from May 15 to December 6, 2016. Data was also obtained from 23 of the horseshoe crabs the following year, from April 14 and October 4, 2017.

The impact of biomedical bleeding on the horseshoe crabs was analyzed in terms of spawning activity, biological rhythms, overall range of movement, depth, and activity levels, while also taking into account the natural shifts in their behavior that come with the changing of the seasons in the Great Bay Estuary.

The authors found that in the first week that the animals were released back into the Great Bay Estuary, bled animals appeared to spawn less than the control animals. The difference was especially pronounced in females, with control females appearing to spawn on average 4.8 times while bled females appeared to spawn on average 2 times.

Another notable trend was that in May and June of 2017, the bled animals did not approach shallower areas in Great Bay but remained in the deeper channels. This poses a problem, since May and June are the months when the horseshoe crabs typically move into shallow water to spawn in the estuary.

For a possible explanation, Owings and her colleagues mention two previous studies, one that took place in a laboratory and one in the field in Cape Cod, that found that biomedically bled horseshoe crabs had disrupted orientation and movements that were more random than control crabs. This disorientation could prevent horseshoe crabs from finding spawning beaches, they write.

They also suggest that the recovery from the bleeding process -- crabs take three to seven days to regain their blood volume, and up to four months for amebocytes to return to baseline levels -- could cause crabs to simply not have as much energy to put towards spawning as they would normally have.

These results are especially troubling since females are already favored in the bleeding process due to their larger size. "If the bled animals, especially females, have alterations in their biological rhythms and mating behaviors, it is likely to further alter the sex ratio on spawning beaches, reduce reproductive output, lower population levels, and decrease the fitness and survival of this keystone species," they write.

The authors recommend that further research is needed to better understand the impact of biomedical bleeding, both in terms of spawning behavior and seasonal movements, so that improvements can be made to reduce both the lethal and sublethal impacts of the process.

We all treasure our vacation time and look forward to that time when we can get away from work. With the arrival of summer comes the prime vacation season and along with it one more reasons to appreciate our vacation time: the value to our heart health. While there has been much anecdotal evidence about the benefits of taking a vacation from work, a new study by Syracuse University professors Bryce Hruska and Brooks Gump and other researchers reveals the benefits of a vacation for our heart health.

"What we found is that people who vacation more frequently in the past 12 months have a lowered risk for metabolic syndrome and metabolic symptoms," says Bryce Hruska, an assistant professor of public health at Syracuse University's Falk College of Sport and Human Dynamics. "Metabolic syndrome is a collection of risk factors for cardiovascular disease. If you have more of them you are at higher risk of cardiovascular disease. This is important because we are actually seeing a reduction in the risk for cardiovascular disease the more vacationing a person does. Because metabolic symptoms are modifiable, it means they can change or be eliminated."

Bottom line: A person can reduce their metabolic symptoms - and therefore their risk of cardiovascular disease - simply by going on vacation.

Hruska says that we are still learning what it is about vacations that make them beneficial for heart health, but at this point, what we do know that it is important for people to use the vacation time that is available to them. "One of the important takeaways is that vacation time is available to nearly 80 percent of full-time employees, but fewer than half utilize all the time available to them. Our research suggests that if people use more of this benefit, one that's already available to them, it would translate into a tangible health benefit."

Researchers have come up with a new way to image cell populations and their genetic contents. Their study, appearing June 20 in the journal Cell, describes how a technique called DNA microscopy helps illuminate the spatial organization of genetic material within cells and tissues without specialized, expensive optical equipment. Using only the sample itself plus reagents delivered with pipettes, DNA microscopy prompts a specimen to provide spatial information about itself as part of a chemical reaction--the products of which can be read out by DNA sequencing.

If light microscopy can be compared to taking photographs of a city from an orbiting satellite, DNA microscopy is like touring that city at street level, says co-author Joshua Weinstein, a postdoctoral associate at the Broad Institute of Harvard and MIT.

Weinstein, computational and systems biologist Aviv Regev, and neuroscientist and molecular biologist Feng Zhang (@zhangf) have used DNA microscopy to image human cancer cell lines. Their goal is to accurately image long stretches of the highly variable gene sequences found in cancer mutations, immune receptors, immunoglobulin genes, and more.

Understanding how cells interact with one another is critical for advancing biological research and clinical treatments. Despite progress in profiling cells' molecular constituents, spatially mapping these constituents is still machine intensive, relying on either light microscopy or slicing and dissecting.

To understand how DNA microscopy works, imagine constructing a map of cities in the United States based on radio signals between radio towers. Even if each city's radio tower pings only its nearest neighbors, algorithms can compile this incomplete, imprecise data into an accurate map.

In DNA microscopy, a chemical reaction tags short segments of DNA called unique molecular identifiers (UMIs). The UMIs are the radio towers, and the radio signals are clouds of copies of UMIs following the physics of diffusion.

Thanks to the UMIs, the sample being studied is now dotted with chemically discrete points. Tracking the collisions between clouds of UMIs copies--with each collision written into DNA sequence products as a chemical reaction--allows researchers to narrow the uncertainty of original UMI positions. The resulting image is a two- or three-dimensional genetically detailed plot of molecular positions in physical space.

The plot represents hundreds of thousands of dimensions dictated by the number of molecules with which the tagged molecules can plausibly communicate.

"A chemical reaction within the specimen encodes information into DNA from which an algorithm can decode the relative positions of molecules without needing to know in advance cell identity or the nature of genetic variation," Weinstein says.

DNA microscopy's weakness is resolving empty spaces, such as large gaps between two cells plated on a dish. If this can be addressed, the researchers hope to more fully explore miniscule spatial structures in the biological world, revealing layers of information that could be hidden by the limits of optical- and electron-based imaging.

"We believe that the most exciting applications of this technology are in areas of biology in which mutations, RNA editing, and other forms of nucleotide-level variation work hand in hand within the organism to either produce physiological outcomes or cause disease," Weinstein says. Examples include understanding how the immune system develops, how the nervous system is wired, and how genetic mutations are present in tumors and affect their interactions with other cells, including immune cells.