Is waxworm new solution for plastic degradation?

Is waxworm new solution for plastic degradation?

Each year, the world produces 300 million tons of plastic, much of which resists degradation and ends up polluting every corner of the globe. But a team of European scientists may have found a unique solution to the plastic problem. They discovered that a common insect can chew sizable holes in a plastic shopping bag within 40 minutes.

Two species of waxworm, Galleria mellonella and Plodia interpunctella have both been observed eating and digesting polyethylene plastic. The waxworms metabolize polyethylene plastic films into ethylene glycol, a compound which biodegrades rapidly. This unusual ability to digest matter classically thought of as non-edible may originate with the waxworm's ability to digest beeswax. Two strains of bacteria, Enterobacter asburiae and Bacillus sp, isolated from the guts of Plodia interpunctella waxworms, have been shown to decompose polyethylene in laboratory testing. In a test with a 28-day incubation period of these two strains of bacteria on polyethylene films, the films' hydrophobicity decreased. In addition, damage to the films' surface with pits and cavities (0.3-0.4 μm in depth) was observed using scanning electron microscopy and atomic-force microscopy.

Placed in a polyethylene shopping bag, approximately 100 Galleria mellonella waxworms consumed almost 0.1 gram (0.0032 ounces) of the plastic over the course of 12 hours in laboratory conditions.

Polyethylene sits around in the environment because its molecules are so hard to break down. Ordinary soil microorganisms don’t have the resources for it. These plastics are built up from the hydrocarbon molecules in oil, and would turn them back into oil after we had used them, regenerating a valuable substance rather than sacrificing it as waste. Chemist have been working long and hard to do that, using special catalyst to induce the chemical reactions. But its tough, and only recently have they started to see progress. Its precisely because was us chemically similar to polyethylene that the was moth caterpillars can biodegrade it.

Those bacteria could provide the ideal solution. They could be brewed up in fermentation vats that would dissolve plastics without anyone having to contemplate breeding vast moth colonies. Alternatively, it might be possible to extract the particular enzymes the caterpillars use and put them to work on their own a kind concentrate of gastric juices.

These are the real reasons why the new discovery is promising, and not because we will soon be feeding plastics bags to caterpillars. As usual with science, you don’t get the solution on a plate, but have to follow clues with patience and care. It doesn’t make for great headlines.

“Mini Brains” in the lab show electrical activity similar to a preemie’s brain

“Mini Brains” in the lab show electrical activity similar to a preemie’s brain

Researchers have developed successfully mini brains in the labs which are essentially a cluster of brain cells perfused in fluids. These brain tissues are now showing electrical activity akin to real brain, explain the researchers and this is a path-breaking development in brain research. The brain activity shown by the clumps of cells is same as that shown by brains of premature babies they explain. The results of the latest development were published in the latest issue of the journal Cell Stem Cell and is titled, “Complex Oscillatory Waves Emerging from Cortical Organoids Model Early Human Brain Network Development.”

While this is a progress in the field of neurobiology, the appearance of the electrical waves has also raised some ethical questions. The researchers describe these brains grown in labs as organoids. These are three dimensional clumps of tissues that are miniature and are simplified versions of the organs that are grown in the lab for research purposes. They can be sued for testing new drugs and agents for example on the brain tissue. These organoids are also useful for study of neurodegenerative diseases such as Alzheimer’s and Parkinsonism and neurodevelopmental conditions such as autism, write the researchers.

Lead neuroscientist from the study said in a statement, “The level of neural activity we are seeing is unprecedented in vitro. We are a step closer to have one model that can actually generate these early stages of a sophisticated neural network.” He and his lab colleagues have been developing the organoids for the last few years and this is the first time that their organoids have shown real neuronal activity. “I think they are replicating like crazy at this stage, and so we are going to have bigger organoids,” he added. “The most incredible thing is that they build themselves,” he said meaning that if the conditions were right the organoids could take charge of their own growth and development.

He explains that the team developed these organoids or mini brains from a bunch of pluripotent cells or stem cells which were coaxed to become brain cells. Pluripotent cells of the body have the capacity to turn into any type of cell when induced. The team created pluripotent cells from the skin cells of a donor. Then they coaxed these stem cells to turn unto cells of the cerebral cortex. This region of the brain forms the major part of the brain and is responsible for functions such as cognitive thoughts, sensation perception, memories etc. Once the organoids were developed, they were allowed to grow in a culture of nutritious broth for a period of nearly 10 months before they were ready for further experiments and testing. All this while, the team kept a close watch on the genetic make-up of the brain as well as on the electrical activity of the brain organoids using electroencephalography (EEG).

By the end of six months in the culture, the organoids started showing some amount of electrical activity. This was significant and recordable says the team. However, these activities were random and not organized as is seen in human brains. With time the electrical beats and waves became more synchronized and the patterns were similar to the bursts of brain activity seen in the brains of preterm infants. The team wrote that the cortex organoids have shown, “phase-amplitude coupling during network-synchronous events.” They explained that these oscillations or electrical activities were sustained by the neurotransmitters “glutamate and GABA”.

The researchers wrote, “While network activity from organoids does not exhibit the full temporal complexity seen in adults, the pattern of alternating periods of quiescence and network-synchronized events is similar to electrophysiological signatures present in preterm human infant EEG.” Not all features were same as preterm infants, but certain signatures were seen, they explained adding that over the past 28 weeks the development of the brains in terms of electrical activity was similar to a developing preterm infant.

These organoids were created in a special way so that they would be deficient in a vital protein that allows the neurons to function like in normal brains. They were also isolated tissues and had no other regions of the brains to connect to, write the researchers. This development of electrical activity over the weeks could be a process of how the brain develops in the fetus and in a preterm infant until in matures in to the human brain. The team wrote, “While we do not claim functional equivalence between the organoids and a full neonatal cortex... the current results represent the first step towards an in vitro model that captures some of the complex spatiotemporal oscillatory dynamics of the human brain.”

Further research focuses on working on these organoids to see their development as well as devise ways they could be used to study neurodevelopmental disorders.

However, this development is also fraught with ethical concerns. Last year in November this study results were presented at the Allen Institute for Brain Science in Seattle. From this institute, neuroscientist Christof Koch said in a statement, “The closer they get to the preterm infant, the more they should worry.” “The closer we come to his goal, the more likely we will get a brain that is capable of sentience and of feeling pain, agony and distress,”. Researchers and experts on bioethics from across the world have lauded the study and also sounded words of caution.

The authors of the study have defended themselves saying that the organoids are engineered to lack a particular protein that could allow the neurons to form networks and connections. They have said that if they detect the organoids showing signs of becoming a conscious human being, the team would shut down the project. 

Green chemists find a way to turn cashew nut shells into sunscreen

A team of international scientists has found an environmentally friendly way of producing potential sunscreens by using cashew nut shells, a waste material.

The team of "green chemists" from the University of the Witwatersrand, along with colleagues from Universities in Germany, Malawi and Tanzania, are working on techniques to produce useful compounds from wood and other fast growing non-edible plant waste, through a chemical process named xylochemistry (wood chemistry). By using cashew nut shells, the team has produced new aromatic compounds that show good UVA and UVB absorbance, which may be applied to protect humans, livestock, as well as polymers or coatings from harmful rays from the sun. The research has just been published as the cover article of the European Journal of Organic Chemistry.

UV rays are damaging to most materials, with its effects leading to the discoloration of dyes and pigments, weathering, yellowing of plastics, loss of gloss and mechanical properties, while it can lead to sunburn, premature aging and even the development of potentially lethal melanomas in both humans and animals.

To mitigate UV damage, both organic and inorganic compounds are used as UV filters. Ideal organic UV filters display a high UV absorption of UVA rays (in the region ranging from 315-400 nm) and UVB rays (280-315 nm). One important family of UV absorber molecules are derived from aromatic compounds known as phenols, which contain a hydrogen-bonded hydroxyl group that plays an important role in the dissipation of the absorbed energy.

For example, an organic compound known as oxybenzone is a common ingredient that has also been added to plastics to limit UV degradation. Apart from their petrochemical origin, a major drawback of current UV protection agents is their negative effect on aquatic ecosystems associated with a poor biodegradability.

As a result, there is growing attention from regulatory bodies and stricter regulations are being enforced on the production of sun filtering products.

"With the current concerns over the use of fossil resources for chemical synthesis of functional molecules and the effect of current UV absorbers in sunscreens on the ecosystem, we aimed to find a way to produce new UV absorbers from cashew nut shell liquid (CNSL) as a non-edible, bio renewable carbon resource," says Professor Charles de Koning, of the Wits School of Chemistry and principal author of the paper, together with Till Opatz from Johannes Gutenberg University in Mainz, Germany.

"Cashew nut shells are a waste product in the cashew-farming community, especially in Tanzania, so finding a useful, sustainable way to use these waste products can lead to completely new, environmentally friendly ways of doing things."

The team has already filed a patent application in order to commercialise the process in South Africa.

DNA Damage Is the Latest Theory on Why Diabetes Increases Cancer Risk

DNA Damage Is the Latest Theory on Why Diabetes Increases Cancer Risk

Last year, researchers determined that people with diabetes have a significantly higher risk of cancer than the general population — but why they do was still a mystery.

Recent research has provided a deeper understanding and firmer theory as to what’s happening in a body with diabetes that increases the likelihood of cancer growth.

“It has been known for a long time that people with diabetes have as much as a 2.5-fold increased risk for certain cancers”. explained by a professor of molecular medicine at the City of Hope National Medical Center in California.

Essentially, DNA in a person with diabetes experiences more damage and isn’t repaired as frequently or successfully when blood sugar levels are high compared to a person with normal blood sugar levels.

*excess levels of insulin that stimulate cancer cell growth

*excess body fat that produces higher levels of adipokines, which promote cancer growth Trusted   Source

*excess hormone production that promotes chronic inflammation, which is linked to cancer

These theories may play a role, research has been unable to produce solid evidence to support them. This led to pursue a different theory focused on DNA damage and blood sugar levels.

Specifically, the research team honed in on a type of DNA damage referred to as “adducts” that develop more frequently in mice with diabetes compared to mice without diabetes.

While a mouse (or person) without diabetes would be generally successful in repairing this type of DNA damage, researchers found that high blood sugar levels directly interfered with the repair process.

Further, two specific proteins — mTORC1 and HIF1α — that play a crucial role in DNA repair were identified as having less activity in people with diabetes.

How microbes generate and use their energy to grow

How do cells generate and use energy? This question might seem simple, but the answer is far from simple. Furthermore, knowing how microbial cell factories consume energy and how proteins are allocated to do so is crucial when working with industrial fermentations.

Now, researchers have shown that it is possible to evoke a shift in the metabolism from fermentation to respiration of E. coli and baker's yeast by optimizing fermentation conditions. This shift means that the cells can be pushed into producing more internal energy (ATP).

"This information can be used to design new, improved cell factories," corresponding author Professor at Chalmers University of Technology, Sweden, and Scientific Director at The Novo Nordisk Foundation Center for Biosustainability at DTU in Denmark Jens Nielsen says.

Together with first-author Postdoc Yu Chen from Department of Biology and Biological Engineering at Chalmers, Jens Nielsen has studied the metabolism of E. coli and baker's yeast through the use of mathematical models and biological experiments. The research has now been published in Proceedings of the National Academy of Sciences (PNAS).

Cells constantly generate high-energy molecules called ATP from the sugar glucose. ATP is the cellular "food" consumed by the workers -- enzymes -- within cells. The enzymes use this energy to build biomass or do other cellular work. The more ATP available, the better the microbial workhorses perform in fermentations; at least in principle -- many other aspects play a part as well.

Using a computational approach, the researchers found out that ATP can be generated by either of two pathways: a high-yielding respiratory pathway resulting in 23.5 ATP's per glucose molecule or a low-yielding fermentative pathway, which only generates 11 ATP's per glucose molecule.

The two pathways supplement each other, but the researchers were able to shift the natural balance between the two by changing the conditions of the fermentation and the amount of sugar and protein available. Furthermore, they showed that the high-yielding pathway needs more protein mass than the low-yielding pathway for consuming glucose at the same rate.

They also showed that making some key enzymes perform better meant that the cells changed from doing low yielding fermentative metabolism to breathing through the high yielding respiratory metabolism.

This shift both results in more intracellular ATP, but also avoids the build-up of fermentative byproducts; acetate in E. coli and ethanol in baker's yeast.

"These byproducts are unwanted and decrease the yield of the sought-for molecules you want to produce in your cell factory," says Jens Nielsen.

Furthermore, the investigators showed that cells performing their best actually used both pathways, not only the high yielding one, and that more proteins available meant more efficiency in a given pathway.

So, the solution to better performing cells in fermentations is not to switch off the fermentative pathway, but rather to allocate more protein to the high-yielding pathway.

The researchers solely exposed the microbes to different fermentation conditions and didn't do genome engineering to evoke these changes. But at the same time, their studies gave an indication of how one can change the cells' metabolism by genome engineering to become more effective in future experiments.

Rheumatoid Arthritis more than a diseases of joints

Rheumatoid Arthritis more than a diseases of joints

An autoimmune disease is a condition in which your immune system mistakenly attacks your body. ... In an autoimmune disease, the immune system mistakes part of your body, like your joints or skin, as foreign. It releases proteins called autoantibodies that attack healthy cells. Rheumatoid arthritis is a chronic inflammatory disorder that can affect more than just your joints. In some people, the condition can damage a wide variety of body systems, including the skin, eyes, lungs, heart and blood vessels.  Unlike the wear-and-tear damage of osteoarthritis, rheumatoid arthritis affects the lining of your joints, causing a painful swelling that can eventually result in bone erosion and joint deformity. The inflammation associated with rheumatoid arthritis is what can damage other parts of the body as well. While new types of medications have improved treatment options dramatically, severe rheumatoid arthritis can still cause physical disabilities. Among the serious complications people with rheumatoid arthritis (RA) experience, cardiovascular disease heads the list. Having RA doubles, the risk of most heart problems, including heart attack, stroke and atherosclerosis — the buildup of fat, cholesterol and cellular debris (plaque) on blood vessel walls. 

Daniel H. Solomon, MD, a professor at Harvard Medical School in Boston and a leading researcher on cardiovascular disease and RA, says the inflammatory processes in RA and heart disease are very similar. In RA, inflammation attacks the synovium — the thin layer of tissue that lines your joints — but it can move to other organs, including the heart. One of the possible victims is the endothelium, the innermost layer of blood vessels. Inflammation causes damage to the blood vessel lining, and plaque builds up. This fatty deposit narrows arteries, raising blood pressure and reducing the flow of blood to your heart and other organs.

Making sense of how inflammation and other risk factors influence RA-related heart disease will help doctors identify and treat high-risk patients early, before they develop symptoms. The challenge is that current cardiovascular risk assessments, which use medical history and lifestyle information to predict a person’s five-year risk of heart disease, aren’t very useful for RA patients. For one thing, standard risk assessments don’t factor in the effects of inflammation or medication.

“Right now, the Holy Grail is finding a better risk assessment,” says Dr. Solomon. In the May 2015 issue of Arthritis and Rheumatology, he and his colleagues published an expanded and validated risk assessment specifically for RA. In addition to traditional cardiovascular risk factors, they also included RA disease activity, disability, prednisone use and years with RA. The researchers found the expanded assessment improved classification of risk compared with traditional risk assessments.

Diabetes: Could vitamin D supplements slow progression?

Diabetes: Could vitamin D supplements slow progression?

Scientists have yet to prove whether vitamin D can treat or slow type 2 diabetes. A new study of people who have recently received a diagnosis of diabetes are at risk of developing it concludes that the vitamin may be beneficial.

According to the Centers for Disease Control and Prevention (CDC), type 2 diabetes and prediabetes now affect more than 100 million people in the United States.

Prediabetes describes a state where in blood glucose levels are higher than normal, which increases the risk of developing diabetes.

In the U.S., an estimated 40% of adults are vitamin D deficient.

Some researchers have wondered if this might play a role in the development and progression of diabetes.

Early studies did find a link between low vitamin D levels and type 2 diabetes. For instance, a study from 2010 found that lower vitamin D levels were associated with reduced insulin sensitivity.

In type 2 diabetes, the body's cells become less sensitive to insulin. Therefore, insulin cannot control blood sugar levels so effectively.

How many Earth-like planets are around sun-like stars?

A new study provides the most accurate estimate of the frequency that planets that are similar to Earth in size and in distance from their host star occur around stars similar to our Sun. Knowing the rate that these potentially habitable planets occur will be important for designing future astronomical missions to characterize nearby rocky planets around sun-like stars that could support life. A paper describing the model appears August 14, 2019 in The Astronomical Journal.

Thousands of planets have been discovered by NASA's Kepler space telescope. Kepler, which was launched in 2009 and retired by NASA in 2018 when it exhausted its fuel supply, observed hundreds of thousands of stars and identified planets outside of our solar system -- exoplanets -- by documenting transit events. Transits events occur when a planet's orbit passes between its star and the telescope, blocking some of the star's light so that it appears to dim. By measuring the amount of dimming and the duration between transits and using information about the star's properties astronomers characterize the size of the planet and the distance between the planet and its host star.

"Kepler discovered planets with a wide variety of sizes, compositions and orbits," said Eric B. Ford, professor of astronomy and astrophysics at Penn State and one of the leaders of the research team. "We want to use those discoveries to improve our understanding of planet formation and to plan future missions to search for planets that might be habitable. However, simply counting exoplanets of a given size or orbital distance is misleading, since it's much harder to find small planets far from their star than to find large planets close to their star."

To overcome that hurdle, the researchers designed a new method to infer the occurrence rate of planets across a wide range of sizes and orbital distances. The new model simulates 'universes' of stars and planets and then 'observes' these simulated universes to determine how many of the planets would have been discovered by Kepler in each `universe.'

"We used the final catalog of planets identified by Kepler and improved star properties from the European Space Agency's Gaia spacecraft to build our simulations," said Danley Hsu, a graduate student at Penn State and the first author of the paper. "By comparing the results to the planets cataloged by Kepler, we characterized the rate of planets per star and how that depends on planet size and orbital distance. Our novel approach allowed the team to account for several effects that have not been included in previous studies."

The results of this study are particularly relevant for planning future space missions to characterize potentially Earth-like planets. While the Kepler mission discovered thousands of small planets, most are so far away that it is difficult for astronomers to learn details about their composition and atmospheres.

"Scientists are particularly interested in searching for biomarkers -- molecules indicative of life -- in the atmospheres of roughly Earth-size planets that orbit in the 'habitable-zone' of Sun-like stars," said Ford. "The habitable zone is a range of orbital distances at which the planets could support liquid water on their surfaces. Searching for evidence of life on Earth-size planets in the habitable zone of sun-like stars will require a large new space mission."

How large that mission needs to be will depend on the abundance of Earth-size planets. NASA and the National Academies of Science are currently exploring mission concepts that differ substantially in size and their capabilities. If Earth-size planets are rare, then the nearest Earth-like planets are farther away and a large, ambitious mission will be required to search for evidence of life on potentially Earth-like planets. On the other hand, if Earth-size planets are common, then there will be Earth-size exoplanets orbiting stars that are close to the sun and a relatively small observatory may be able to study their atmospheres.

"While most of the stars that Kepler observed are typically thousands of light years away from the Sun, Kepler observed a large enough sample of stars that we can perform a rigorous statistical analysis to estimate of the rate of Earth-size planets in the habitable zone of nearby sun-like stars." said Hsu.

Based on their simulations, the researchers estimate that planets very close to Earth in size, from three-quarters to one-and-a-half times the size of earth, with orbital periods ranging from 237 to 500 days, occur around approximately one in four stars. Importantly, their model quantifies the uncertainty in that estimate. They recommend that future planet-finding missions plan for a true rate that ranges from as low about one planet for every 33 stars to as high as nearly one planet for every two stars.

"Knowing how often we should expect to find planets of a given size and orbital period is extremely helpful for optimize surveys for exoplanets and the design of upcoming space missions to maximize their chance of success," said Ford. "Penn State is a leader in brining state-of-the-art statistical and computational methods to the analysis of astronomical observations to address these sorts of questions. Our Institute for CyberScience (ICS) and Center for Astrostatistics (CASt) provide infrastructure and support that makes these types of projects possible."

The Center for Exoplanets and Habitable Worlds at Penn State includes faculty and students who are involved in the full spectrum of extrasolar planet research. A Penn State team built the Habitable Zone Planet Finder, an instrument to search for low-mass planets around cool stars, which recently began science operations at the Hobby-Eberly Telescope, of which Penn State is a founding partner. A second Penn State-built spectrograph is in being tested before it begins a complementary survey to discover and measure the masses of low-mass planets around sun-like stars. This study makes predictions for what such planet surveys will find and will help provide context for interpreting their results.

In addition to Ford and Hsu, the research team includes Darin Ragozzine and Keir Ashby at Brigham Young University. The research was supported by NASA; the U.S. National Science Foundation (NSF); and the Eberly College of Science, the Department of Astronomy and Astrophysics, the Center for Exoplanets and Habitable Worlds, and the Center for Astrostatistics at Penn State. Advanced computing resources and services were provided by the Penn State Institute for CyberScience, including the NSF funded CyberLAMP cluster.

Materials that can revolutionize how light is harnessed for solar energy

Researchers at Columbia University have developed a way to harness more power from singlet fission to increase the efficiency of solar cells, providing a tool to help push forward the development of next-generation devices.

In a study published this month in Nature Chemistry, the team details the design of organic molecules that are capable of generating two excitons per photon of light, a process called singlet fission. The excitons are produced rapidly and can live for much longer than those generated from their inorganic counterparts, which leads to an amplification of electricity generated per photon that is absorbed by a solar cell.

"We have developed a new design rule for singlet fission materials," said Luis Campos, an associate professor of chemistry and one of three principal investigators on the study. "This has led us to develop the most efficient and technologically useful intramolecular singlet fission materials to date. These improvements will open the door for more efficient solar cells."

All modern solar panels operate by the same process -- one photon of light generates one exciton, Campos explained. The exciton can then be converted into electric current. However, there are some molecules that can be implemented in solar cells that have the ability to generate two excitons from a single photon -- a process called singlet fission. These solar cells form the basis for next-generation devices, which are still at infancy. One of the biggest challenges of working with such molecules, though, is that the two excitons "live" for very short periods of time (tens of nanoseconds), making it difficult to harvest them as a form of electricity.

In the current study, funded in part by the Office of Naval Research, Campos and colleagues designed organic molecules that can quickly generate two excitons that live much longer than the state-of-the-art systems. It is an advancement that can not only be used in next-generation solar energy production, but also in photocatalytic processes in chemistry, sensors, and imaging, Campos explained, as these excitons can be used to initiate chemical reactions, which can then be used by industry to make drugs, plastics, and many other types of consumer chemicals.

"Intramolecular singlet fission has been demonstrated by our group and others, but the resulting excitons were either generated very slowly, or they wouldn't last very long," Campos said. "This work is the first to show that singlet fission can rapidly generate two excitons that can live for a very long time. This opens the door to fundamentally study how these excitons behave as they sit on individual molecules, and also to understand how they can be efficiently put to work in devices that benefit from light-amplified signals."

The team's design strategy should also prove useful in separate areas of scientific study and have many other yet-unimaginable applications, he added.

Campos' study co-authors are: Samuel Sanders and Andrew Pun, of Columbia University; Matthew Y. Sfeir, of City University of New York; and Amir Asadpoordarvish, of the University of New South Wales.

Brain molecule identified as key in anxiety model

Boosting a single molecule in the brain can change "dispositional anxiety," the tendency to perceive many situations as threatening, in nonhuman primates, researchers from the University of California, Davis, and the University of Wisconsin-Madison have found. The molecule, neurotrophin-3, stimulates neurons to grow and make new connections

The finding provides hope for new strategies focused on intervening early in life to treat people at risk for anxiety disorders, depression and related substance abuse. Current treatments work for only a subset of people and often only partially relieve symptoms.

"There are millions of people worldwide who suffer from debilitating anxiety and depressive disorders," said Andrew Fox, an assistant professor in the UC Davis Department of Psychology and a researcher at the California National Primate Research Center."These disorders are also some of the leading causes of disability and days lost to disability."

Fox co-led the study with Tade Souaiaia of the State University of New York Downstate Medical Center. Ned Kalin, chair of psychiatry at the University of Wisconsin-Madison School of Medicine and Public Health, is also a corresponding author on the study published August 15 in the journal Biological Psychiatry.

Anxiety disorders often emerge around adolescence and can continue to affect people for most of their lives. Currently, researchers can identify children who display an extreme anxious or inhibited temperament; these young people are at risk to develop stress-related psychopathologies as they transition to adulthood.

Changes in the amygdala

The roots of the study come from research done by the group about eight years ago in preadolescent rhesus macaques, when researchers got their first glimpse of molecular alterations in the dorsal amygdala, a brain region important in emotional responses.

The authors speculated that altered processes in this region might underlie early-life anxiety. Since then, the research team sequenced RNA from the dorsal amygdala to identify molecules related to dispositional anxiety and dorsal amygdala function. They eventually narrowed the potential molecules and selected neurotrophin-3, a growth factor, for further study.

The researchers used an altered virus to boost levels of neurotrophin-3 in the dorsal amygdala of juvenile rhesus macaques. They found that the increase of neurotrophin-3 in the dorsal amygdala lead to a decrease in anxiety-related behaviors, particularly behaviors associated with inhibition, a core feature of the early-life risk for developing anxiety disorders in humans. Subsequent brain imaging studies of these animals found that neurotrophin-3 changed activity throughout the distributed brain regions that contribute to anxiety.

Fox hopes other scientists can build on their research as an example of the kind of "deep science" that can transform how we understand psychopathology. The team has included a list of additional promising molecules that may warrant future investigation.

"We're only just beginning. Neurotrophin-3 is the first molecule that we've been able to show in a non-human primate to be causally related to anxiety. It's one of potentially many molecules that could have this affect. There could be hundreds or even thousands more," said Fox.

Other authors on the paper are: James Knowles, Jae Mun (Hugo) Kim, and Joseph Nguyen of State University of New York Downstate Medical Center; Ethan Brodsky, Walter Block, Andrew Alexander, Jonathan Oler, Rothem Kovner, Marissa Riedel, Delores French, Eva Fekete, Miles Olsen, Matthew Rabska and Patrick Roseboom of the University of Wisconsin-Madison. This work was supported by grants from the National Institutes of Health.

Diarrhea-causing bacteria adapted to spread in hospitals

Scientists have discovered that the gut-infecting bacterium Clostridium difficile is evolving into two separate species, with one group highly adapted to spread in hospitals. Researchers at the Wellcome Sanger Institute, London School of Hygiene & Tropical Medicine and collaborators identified genetic changes in the newly-emerging species that allow it to thrive on the Western sugar-rich diet, evade common hospital disinfectants and spread easily. Able to cause debilitating diarrhea, they estimated this emerging species started to appear thousands of years ago, and accounts for over two thirds of healthcare C. difficile infections.

Published in Nature Genetics today (12 August), the largest ever genomic study of C. difficile shows how bacteria can evolve into a new species, and demonstrates that C. difficile is continuing to evolve in response to human behaviour. The results could help inform patient diet and infection control in hospitals.

C. difficile bacteria can infect the gut and are the leading cause of antibiotic-associated diarrhea worldwide. While someone is healthy and not taking antibiotics, millions of 'good' bacteria in the gut keep the C. difficile under control. However, antibiotics wipe out the normal gut bacteria, leaving the patient vulnerable to C. difficile infection in the gut. This is then difficult to treat and can cause bowel inflammation and severe diarrhea.

Often found in hospital environments, C. difficile forms resistant spores that allow it to remain on surfaces and spread easily between people, making it a significant burden on the healthcare system.

To understand how this bacterium is evolving, researchers collected and cultured 906 strains of C. difficile isolated from humans, animals, such as dogs, pigs and horses, and the environment. By sequencing the DNA of each strain, and comparing and analysing all the genomes, the researchers discovered that C. difficile is currently evolving into two separate species.

Dr Nitin Kumar, joint first author from the Wellcome Sanger Institute, said: "Our large-scale genetic analysis allowed us to discover that C. difficile is currently forming a new species with one group specialised to spread in hospital environments. This emerging species has existed for thousands of years, but this is the first time anyone has studied C. difficile genomes in this way to identify it. This particular bacteria was primed to take advantage of modern healthcare practices and human diets, before hospitals even existed."

The researchers found that this emerging species, named C. difficile clade A, made up approximately 70 per cent of the samples from hospital patients. It had changes in genes that metabolise simple sugars, so the researchers then studied C. difficile in mice, and found that the newly emerging strains colonised mice better when their diet was enriched with sugar. It had also evolved differences in the genes involved in forming spores, giving much greater resistance to common hospital disinfectants. These changes allow it to spread more easily in healthcare environments.

Dating analysis revealed that while C. difficile Clade A first appeared about 76,000 years ago, the number of different strains of this started to increase at the end of the 16th Century, before the founding of modern hospitals. This group has since thrived in hospital settings with many strains that keep adapting and evolving.

Dr Trevor Lawley, the senior author from the Wellcome Sanger Institute, said: "Our study provides genome and laboratory based evidence that human lifestyles can drive bacteria to form new species so they can spread more effectively. We show that strains of C. difficile bacteria have continued to evolve in response to modern diets and healthcare systems and reveal that focusing on diet and looking for new disinfectants could help in the fight against this bacteria."

Prof Brendan Wren, an author from the London School of Hygiene & Tropical Medicine, said: "This largest ever collection and analysis of C. difficile whole genomes, from 33 countries worldwide, gives us a whole new understanding of bacterial evolution. It reveals the importance of genomic surveillance of bacteria. Ultimately, this could help understand how other dangerous pathogens evolve by adapting to changes in human lifestyles and healthcare regimes which could then inform healthcare policies."

How many Earth-like planets are around sun-like stars?

A new study provides the most accurate estimate of the frequency that planets that are similar to Earth in size and in distance from their host star occur around stars similar to our Sun. Knowing the rate that these potentially habitable planets occur will be important for designing future astronomical missions to characterize nearby rocky planets around sun-like stars that could support life. A paper describing the model appears August 14, 2019 in The Astronomical Journal.

Thousands of planets have been discovered by NASA's Kepler space telescope. Kepler, which was launched in 2009 and retired by NASA in 2018 when it exhausted its fuel supply, observed hundreds of thousands of stars and identified planets outside of our solar system -- exoplanets -- by documenting transit events. Transits events occur when a planet's orbit passes between its star and the telescope, blocking some of the star's light so that it appears to dim. By measuring the amount of dimming and the duration between transits and using information about the star's properties astronomers characterize the size of the planet and the distance between the planet and its host star.

"Kepler discovered planets with a wide variety of sizes, compositions and orbits," said Eric B. Ford, professor of astronomy and astrophysics at Penn State and one of the leaders of the research team. "We want to use those discoveries to improve our understanding of planet formation and to plan future missions to search for planets that might be habitable. However, simply counting exoplanets of a given size or orbital distance is misleading, since it's much harder to find small planets far from their star than to find large planets close to their star."

To overcome that hurdle, the researchers designed a new method to infer the occurrence rate of planets across a wide range of sizes and orbital distances. The new model simulates 'universes' of stars and planets and then 'observes' these simulated universes to determine how many of the planets would have been discovered by Kepler in each `universe.'

"We used the final catalog of planets identified by Kepler and improved star properties from the European Space Agency's Gaia spacecraft to build our simulations," said Danley Hsu, a graduate student at Penn State and the first author of the paper. "By comparing the results to the planets cataloged by Kepler, we characterized the rate of planets per star and how that depends on planet size and orbital distance. Our novel approach allowed the team to account for several effects that have not been included in previous studies."

The results of this study are particularly relevant for planning future space missions to characterize potentially Earth-like planets. While the Kepler mission discovered thousands of small planets, most are so far away that it is difficult for astronomers to learn details about their composition and atmospheres.

"Scientists are particularly interested in searching for biomarkers -- molecules indicative of life -- in the atmospheres of roughly Earth-size planets that orbit in the 'habitable-zone' of Sun-like stars," said Ford. "The habitable zone is a range of orbital distances at which the planets could support liquid water on their surfaces. Searching for evidence of life on Earth-size planets in the habitable zone of sun-like stars will require a large new space mission."

How large that mission needs to be will depend on the abundance of Earth-size planets. NASA and the National Academies of Science are currently exploring mission concepts that differ substantially in size and their capabilities. If Earth-size planets are rare, then the nearest Earth-like planets are farther away and a large, ambitious mission will be required to search for evidence of life on potentially Earth-like planets. On the other hand, if Earth-size planets are common, then there will be Earth-size exoplanets orbiting stars that are close to the sun and a relatively small observatory may be able to study their atmospheres.

"While most of the stars that Kepler observed are typically thousands of light years away from the Sun, Kepler observed a large enough sample of stars that we can perform a rigorous statistical analysis to estimate of the rate of Earth-size planets in the habitable zone of nearby sun-like stars." said Hsu.

Based on their simulations, the researchers estimate that planets very close to Earth in size, from three-quarters to one-and-a-half times the size of earth, with orbital periods ranging from 237 to 500 days, occur around approximately one in four stars. Importantly, their model quantifies the uncertainty in that estimate. They recommend that future planet-finding missions plan for a true rate that ranges from as low about one planet for every 33 stars to as high as nearly one planet for every two stars.

"Knowing how often we should expect to find planets of a given size and orbital period is extremely helpful for optimize surveys for exoplanets and the design of upcoming space missions to maximize their chance of success," said Ford. "Penn State is a leader in brining state-of-the-art statistical and computational methods to the analysis of astronomical observations to address these sorts of questions. Our Institute for CyberScience (ICS) and Center for Astrostatistics (CASt) provide infrastructure and support that makes these types of projects possible."

The Center for Exoplanets and Habitable Worlds at Penn State includes faculty and students who are involved in the full spectrum of extrasolar planet research. A Penn State team built the Habitable Zone Planet Finder, an instrument to search for low-mass planets around cool stars, which recently began science operations at the Hobby-Eberly Telescope, of which Penn State is a founding partner. A second Penn State-built spectrograph is in being tested before it begins a complementary survey to discover and measure the masses of low-mass planets around sun-like stars. This study makes predictions for what such planet surveys will find and will help provide context for interpreting their results.

In addition to Ford and Hsu, the research team includes Darin Ragozzine and Keir Ashby at Brigham Young University. The research was supported by NASA; the U.S. National Science Foundation (NSF); and the Eberly College of Science, the Department of Astronomy and Astrophysics, the Center for Exoplanets and Habitable Worlds, and the Center for Astrostatistics at Penn State. Advanced computing resources and services were provided by the Penn State Institute for CyberScience, including the NSF funded CyberLAMP cluster.