Culture

Largescale 'disturbances', including fires, harvesting, windstorms and insect outbreaks, which kill large patches of forest, are responsible for more than a tenth of tree death worldwide, according to new research at the University of Birmingham.

The research, published in Nature Geoscience, also showed wide regional variation, with parts of Scandinavia, the USA, Canada and Russia having a particularly high frequency of these disturbances.

Mapping the causes of tree death is important because it helps scientists understand how the world's carbon stocks - stored in forests - are affected by these disturbances and the frequency with which they occur.

Researchers in the Institute for Forest Research (BIFoR) at the University of Birmingham studied satellite-based observations of forest lost between 2000 and 2014, and assessed the typical time interval between large disturbance events across the world's forests.

The team then used a computational model to calculate the impact of these events on tree deaths - measured as the amount of carbon stored in the wood of dead trees - and found that they accounted for 12 per cent of tree death overall. Their simulations showed how even small changes to the frequency of large-scale disturbances can have a significant effect on forest carbon stocks in 44 per cent of the world's dense forests.

The model will enable scientists to better understand the context of events such as the recent wildfires which devastated parts of the Arctic.

Lead author, Dr Thomas Pugh, of the Institute for Forest Research at the University of Birmingham, said: "Large patches of dead forest make a dramatic impact on the landscape, be they caused by fires, harvesting, windstorms or insect outbreaks. But despite having been able to observe these events from space for many years, the contribution that they make to tree mortality and impact on forest carbon storage across the world has been unknown."

"Now we can see much more clearly where large disturbances play major roles and where forest carbon stocks are sensitive to changes in disturbance frequency."

He added: "This year's large fires across the Arctic may just be an anomaly, or they could be a sign that disturbances in that region are becoming more frequent relative to the historical norm. If that's the case, we can expect large amounts of carbon to be released from these forests over the coming century and perhaps wholesale changes in the mix of vegetation that make up the forests."

More work is now needed to study the reasons behind the remaining 88 per cent of the world's tree death to calculate the contributions of factors such as competition, drought, and older trees dying off.

Are you tired? A new study of young and middle-aged adults shows it could be happening because of the way society functions in your part of the world.

Researchers from Flinders University and the University of Helsinki collaborated with Finnish company, Polar, to compare the sleeping habits of 17,335 people wearing fitness trackers to measure their 14 day sleep patterns.

As published in in Sleep Medicine, they looked at sleep duration, sleep midpoint and weekend catch up for participants aged 16 to 30.

Sleep expert Professor Michael Gradisar says the study indicates differences in sleep durations shift dramatically throughout adolescence and stabilise near 30 years of age around the world.

"Sleep duration ranged from 7:53 hrs at age 16 to 7:29 hrs at age 30. There were also clear differences between females and males throughout adolescence and young adulthood, with girls having longer sleep and earlier timed sleep." says Professor Gradisar.

"In recent decades, there have been reports of delayed sleep in young people, characterised by very late bedtimes, and difficulties waking up in the morning at a socially-appropriate time. As sleep is a central element in functioning, health, and wellbeing, the reliable detection of sleep patterns is a key interest."

The results also show location matters- with people in the Middle East, Asia and Southern Europe getting significantly less sleep when compared to everyone else.

"Young adults in Asia had the shortest sleep duration (6hr 30min), whereas those in Oceania (7hr 14min) and Europe, (7hr 7min) had the longest. Young adults in Central and Southern America and the Middle East also reported short sleep (6hr 40min),"

"Higher work and educational demands in Asian countries compared to the west likely explain the later shorter sleep duration, coupled with similar catch up sleep, seen in those Asian regions."

"For example, when I was in Hong Kong last year speaking to colleagues, they informed me of Typhoon Mangkhut, which was one of the most destructive storms in the city's history. The very next day, workers were ordered to go back to work by a billionaire tycoon. My colleagues spoke of walking to work, stepping over fallen trees, and broken windows and paper in the streets. This is a city that doesn't rest - and part of a region that doesn't sleep much."

"So our findings suggest that cultural factors likely impinge upon the sleep opportunity of young people around the world."

HOUSTON - (Aug. 12, 2019) - Rice University scientists have found a way to engineer a new kind of cell differentiation in bacteria, inspired by a naturally occurring process in stem cells.

They have created a genetic circuit able to produce genetically distinguished cells of Escherichia coli as the bacterium divides. By controlling this process, it is possible to create diverse communities of microbes that exhibit complex, non-native behaviors.

Rice synthetic biologist Matthew Bennett and Sara Molinari, a former student in the university's Systems, Synthetic and Physical Biology Ph.D. program, led the project to show how manipulating the genetic code of plasmids -- free-floating pieces of circular DNA in cells -- can be used to obtain stem cell-like differentiation in bacteria.

"Stem cells have the remarkable ability to divide asymmetrically," Bennett said. "Upon division, the original stem cell stays the same, but the new daughter cell has a completely new phenotype. That's asymmetric cell division, and multicellular organisms use it to help control their cellular makeup.

"As a synthetic biologist, I think a lot about creating and controlling differentiated cell types within a multicellular population," he said. "Here, we've taken what we know about stem cells and engineered the means to do it in bacteria."

The researchers reported the development, which they call asymmetric plasmid partitioning (APP), in Nature Chemical Biology.

Molinari first discovered how to force plasmids in E. coli to aggregate in a single cluster so they do not distribute homogeneously during cell division, but rather are inherited by only one of the two daughter cells. The plasmid-laden daughter cell remains identical to the progenitor cell, while its sibling becomes genetically distinct as it loses the genetic information present on the plasmids.

She then expanded the synthetic circuit to induce the simultaneous asymmetric partitioning of two plasmid species in a single cell, resulting in four genetically distinct E. coli. Some of the cells have motility programmed in; they can literally go their own way and help form patterns in the resulting colony.

"When we started, we were thinking about creating materials that have to be able to sense and adapt to an environment," said Molinari, who recently earned her doctorate at Rice. "We thought if we could mimic this feature of higher-order tissues, we would increase the robustness of our colonies and their ability to perform tasks. The challenge was to engineer a population of bacteria that becomes something else whenever it's needed."

Molinari and her colleagues hit the jackpot on their first try with E. coli. "There was no canonical way to engineer asymmetrical cell division," she said. "It was a crazy idea, and it magically worked the first time.

"But there was something we couldn't completely figure out about the system," Molinari said. "It took two years to find out I made a cloning mistake when I got this protein and put it in my plasmid. I had randomly added 17 amino acids at the beginning of the protein, and that made the whole system work."

With that knowledge, she proceeded to improve upon the hydrophobic proteins that cluster in cells while they bind to target plasmids, holding them in place.

Bennett noted natural processes either load enough plasmids into a cell to ensure some land in each daughter cell or actively pull plasmids into each of the new cells to ensure they remain identical. "We have shown we can outcompete those processes," he said.

APP could turn simple organisms into complicated systems that enhance understanding of multicellular life. "We're pretty good at designing bacteria," Bennett said. "We've been doing that for years now. I think the field has evolved to the point where we can do amazing things with bacteria and people are asking what else we can do."

The new discovery, he said, provides a path forward.

"There are three main hallmarks to multicellular life," he said. "One is differentiation through asymmetric cell division. Another is intercellular communication, which synthetic biologists have been engineering for years. And the third is cell adhesion, so cells stay where they're supposed to and stick to each other. If we can control all those things together, we can talk about engineering interesting multicellular lifeforms.

"It starts to feel a bit like science fiction, for sure," he said.

New research, published today in the journal Nature Climate Change, has found that Antarctic icebergs can weaken and delay the effect of Global Warming in the Southern Hemisphere.

Unabated Global Warming threatens the stability of the Antarctic ice sheet. Recent observations reveal a rapid thinning of the Pine Island and Thwaites glacier regions in Antarctica, which can be attributed partly to warming oceans. These findings have raised concerns of an accelerated ice loss of the West Antarctic ice sheet and potential contributions to global sea level rise. Ice loss can occur in the form of melt-induced (liquid) freshwater discharge into the ocean, or through (solid) iceberg calving.

With a projected future retreat of the Antarctic ice sheet, scientists expect an intensification of iceberg discharge. Icebergs can persist for years and are carried by winds and currents through the Southern Ocean until they reach warmer waters and ultimately melt. The melting process cools ocean waters like ice cubes in a cocktail glass. Furthermore, freshwater discharge from icebergs impacts currents by lowering ocean salinity. Whether this "iceberg effect'' can slow down or alter future climate change in the Southern Hemisphere has remained an open question.

Climate researchers from the University of Hawaii (USA), the IBS Center for Climate Physics (South Korea), Penn State University (USA) and University of Massachusetts (USA) have now quantified for the first time this effect of Antarctic iceberg calving on future Southern Hemisphere climate. The team ran a series of Global Warming computer simulations, which include the combined freshwater and cooling effects of icebergs on the ocean. The size and number of icebergs released in their model mimics the gradual retreat of the Antarctic ice sheet over a period of several hundred years. By turning on an off the "iceberg effect" in their climate model, the researchers discovered that icebergs can significantly slow down human-induced warming in the Southern Hemisphere, impacting global winds and rainfall patterns.

"Our results demonstrate that the effect of Antarctic melting and icebergs needs to be included in computer model simulations of future climate change. Climate models currently used in the 6th climate change assessment of the Intergovernmental Panel on Climate Change (IPCC) do not account for this process." says Dr. Fabian Schloesser, lead author of the study in Nature Climate Change.

Dr. Tobias Friedrich, coauthor of the study, adds: "To melt the icebergs released over the 21st century in one of our extreme Antarctic ice-sheet retreat scenarios would require 400 times the current annual world energy consumption. Global sea level would rise by about 80 cm, impacting many coastal regions and communities worldwide."

Recent studies have suggested that the impact of Antarctic meltwater discharge on the ocean could lead to further acceleration of ice sheet melting and global sea level rise. The present study paints a more complex picture of the underlying dynamics. Including the cooling effect of icebergs largely compensates for the processes that were previously thought to accelerate Antarctic melting.

"Our research highlights the role of icebergs in global climate change and sea level rise. Depending on how quickly the West Antarctic ice sheet disintegrates, the iceberg effect can delay future warming in cities such as Buenos Aires and Cape Town by 10-50 years." says Prof. Axel Timmermann, corresponding author of the study and Director of the IBS Center for Climate Physics.

The research team plans to further quantify the interplay between ice and climate and its effect on global sea level with a new computer model that they developed.

Bacteria can swim against the current - and often this is a serious problem, for example when they spread in water pipes or in medical catheters. How they manage to do this has not been clear until now. An international research team, including Andreas Zöttl from the TU Wien (Vienna), was able to answer this question: With the help of experiments and mathematical calculations, a formula was found that describes all essential aspects of this amazing bacterial motion behavior. This could make it possible to prevent or at least slow down the spread of bacteria by designing special tube surfaces. The results have now been published in the journal "Nature Communications".

Between Physics and Biology

Many types of bacteria, such as the E. coli bacteria, which can often become a health hazard in water, move around with the help of small flagella tails. "This is quite different from the motion of a fish," says Andreas Zöttl from the Institute for Theoretical Physics at Vienna University of Technology. "Fish feel the direction of the current and can decide to swim in a specific direction. Bacteria are much simpler. Their behavior can be explained by very basic physical laws."

Bacteria often accumulate on surfaces overflown by liquids - this can be the poorly cleaned shower cubicle, a sewage pipe or even a catheter. "The bacteria's behavior is particularly interesting on such surfaces," says Andreas Zöttl, "because it turns out that it is precisely there, directly on the surfaces, that the bacteria often migrate against the current. They are therefore not washed away with the wastewater, but they move upstream." Together with colleagues from Stanford University, Oxford University and the ESPCI in Paris, Andreas Zöttl set out to find a physical explanation for this effect.

Theory and experiment

Andreas Zöttl used mathematical methods: He calculated how a bacterium can be aligned and rotated in a flowing liquid, how the flow interacts with the movement of the flagella and which movement possibilities result from this. "This leads to the remarkable result that there are different, clearly distinguishable types of movement, depending on the strength of the flow," explains Andreas Zöttl.

In slow currents, the bacteria simply rotate in a circle, at a certain point they begin to move against the direction of flow. In even stronger currents, they oscillate back and forth on the surface, or they separate into two different groups that move in different directions. With a single mathematical formula, a whole range of bacterial movement patterns can be explained.

At the same time, new technological methods have been developed in Paris to measure the movements of individual bacteria with specially controlled microscopes - and these measurements revealed exactly the same clearly distinguishable types of movement that the theoretical calculations had shown before. "This tells us that our theory is correct," says Andreas Zöttl. "What is particularly nice about this is that the results are very robust: They do not depend sensitively on any details, so our formula can be applied to many different types of bacteria". Even DNA strands floating around in the cell plasma can be described correctly with the new theory.

The team hopes that the newly gained understanding of bacterial motion will enable them to find methods that prevent bacteria from moving. "In future, it might be possible to equip catheters with a specific geometric surface structure that prevents bacteria from migrating against the current," hopes Andreas Zöttl.

The analysis of gene products in cells is an important tool for diagnosing disease and the design of new active substances in biological and medical research. At Helmholtz Zentrum München, a method of targeted RNA sequencing (transcriptome analysis) has now been developed, which precisely detects the smallest amounts of gene transcripts in single cells. The method enables the identification and enrichment of individual selected molecules in a sample in order to investigate their cellular function. This makes it possible to selectively characterize genes in each cell with high precision. Their work has been published in Genome Biology.

Single cell RNA sequencing is based on the investigation of the molecular transcripts generated by active regions of the genome in individual cells. Depending on type and stage of development, cells activate different gene sets that are read from RNA molecules and translated into proteins. The number of mRNA molecules - also called transcripts - per gene in a given cell can inform us about their identity and their physiological response to internal or external signals. These can be diseases, aging process, environmental influences or reactions to pharmacological agents. However, the detection of genes that are only expressed in moderate to low concentrations poses a major challenge for current single cell RNA sequencing techniques. They mostly detect so-called housekeeping genes, which, unlike regulated genes, are constantly expressed.

The BART-Seq method, developed by a team around Dr. Micha Drukker, Institute of Stem Cell Research, and PhD student Fatma Uzbas, addresses this problem by enriching selected transcripts for sequencing. BART-Seq stands for "Barcode Assembly foR Targeted Sequencing". Primer sets and DNA barcodes are combined, so that they can simultaneously amplify the transcripts of the genes of interest. "We have developed a novel way to index primers with DNA barcodes by a simple synthesis reaction," explains Micha Drukker. Sequenced transcripts can thus be traced back to the individual cells from which they originated. Since the analysis focuses on the selected genes, it is possible to obtain high-resolution information about these genes and thus characterize each cell individually.

The method is inexpensive and does not require specialized and expensive instrumentation. Any research group with access to a Next-Generation Sequencing device can use BART-Seq both for single cells and for the analysis of RNA or genomic DNA bulk specimens from thousands of samples.

Together with Philipp Angerer, Nikola Müller and Fabian Theis from the Institute of Computational Biology at Helmholtz Zentrum München, Drukker's team has developed software for the design of primers and barcodes as well as for the analysis of sequencing data. In order to make the method accessible to all research groups, the software is freely available on the Internet.

Micha Drukker and his team colleagues hope that their method will become an integral part of the toolkit for basic and applied research. Projects on drug screening, such as the measurement of the reaction of cultured β cells to drugs, or precision gene-editing technology using CRISPR-Cas9 could benefit greatly from BART-Seq.

Walnut consumption may offer protection against ulcerative colitis, according to a new study by researchers at UConn Health and Texas A&M University.

Through their complex array of natural compounds and phytochemicals, walnuts have been shown to provide a multitude of health benefits, including protection against in?ammation and colon cancer.

The latest findings from a study of mice, published in the journal Nutrients, found that walnut consumption also offered protection against experimentally-induced ulcerative colitis.

Ulcerative colitis is a form of inflammatory bowel disease (IBD) characterized by chronic inflammation of the gastrointestinal tract. In 2015, an estimated 3 million U.S. adults reported being diagnosed with IBD -- either Crohn's disease or ulcerative colitis, according to the Centers for Disease Control.

The current study, led by Dr. Daniel Rosenberg, professor of medicine, and Masako Nakanishi, assistant professor, at the Center for Molecular Oncology at UConn Health, assessed the effects of walnut dietary supplementation in a colitis model, where colonic mucosal injury is induced by the ulcerogenic agent dextran sodium sulfate. Walnuts accounted for 14 percent of the daily diet in the study -- equivalent of 20 to 25 walnuts in a human.

When mice were given walnuts for about two weeks, they suffered much less injury to their colons during an episode of ulcerative colitis and the repair process of the colonic mucosa seemed to be enhanced following the walnut supplementation. The process is referenced as a pre-conditioning of the colon by walnut ingestion. Although it could not be determined whether the pre-conditioned colon was resisting the initial ulcerogenic (ulcer-inducing) damage or facilitating the repair of the damage, the extent of injury in the walnut-treated mice was far less than in the non-treated mice.

Further, when changes in metabolites in the fecal stream and tissue were assessed -- after two weeks of being fed walnuts -- a number of alterations were observed. This additional discovery, conducted by Cory Klemashevich, assistant research scientist at Texas A&M University, showed some changes in metabolites which could be key in further understanding how walnuts may be metabolized and working in the colon.

"We are continuing our work to understand whether those metabolic changes are part of the protection," says Rosenberg. "We are not suggesting that people with ulcerative colitis be maintained on a large walnut diet between active flares. But, we are hoping that we'll be able to determine the active compounds -- nutrients, phytochemicals -- in walnuts that cause protection."

More research is being done to understand the impact on humans. Currently, Rosenberg's lab is running a clinical trial conducted by Bruno S. Lemos, postdoctoral fellow. Participants are consuming two ounces of walnuts daily for three weeks before a scheduled colonoscopy. Their metabolites and gut microbiota will be analyzed, and their biomarkers assessed.

Scientists have found a rare, inherited gene mutation that raises the risk of pancreatic cancer and other malignancies

In the future, individuals with a strong family history of pancreatic cancer could be tested to determine if they carry the mutation.

BOSTON - Scientists studying a highly cancer-prone family have identified a rare, inherited gene mutation that dramatically raises the lifetime risk of pancreatic and other cancers.

The discovery of the previously unknown mutation, reported in Nature Genetics by investigators from Dana-Farber/Brigham and Women's Cancer Center, could lead to routine testing of individuals with a strong family history of pancreatic cancer to determine if they carry the mutation, occurring in the gene known as RABL3. If so, they could be screened to detect pancreatic cancer in an earlier, potentially more treatable stage. "There is evidence that catching pancreatic cancer through screening of high-risk individuals may improve outcomes," said Sahar Nissim, MD, PhD, a cancer geneticist and gastroenterologist at Dana-Farber Cancer Institute and Brigham and Women's Hospital, and first author of the study. In addition, their relatives could choose to be tested to learn if they carry the mutation. Senior author of the report is Wolfram Goessling, MD, PhD, Chief of Gastroenterology at the Massachusetts General Hospital.

About 10 percent of pancreatic cancers have a familial pattern, and in most cases the causative genetic flaw isn't known, although some mutations have been identified. One inherited mutation that can predispose individuals to pancreatic cancer occurs in the gene BRCA2, the gene also known to cause some breast and ovarian cancers. The newly identified mutation in the gene RABL3 similarly increases the likelihood that cancer will develop during the person's lifetime.

"Pancreatic cancer is a challenging disease with limited treatment options," the investigators said. "Familial pancreatic cancer, in which an inherited genetic mutation is responsible for multiple cases in a single family, may give us precious insights that open new preventative and treatment options for pancreatic cancer."

The RABL3 mutation was pinpointed when scientists studied a family in which there were five relatives with pancreatic cancer and multiple family members with other cancers - a pattern suggesting an inherited mutation causing predisposition to developing cancer. The analysis included sequencing the DNA of one family member, who developed pancreatic cancer at age 48, and that of her paternal uncle, who was diagnosed with it at age 80. The RABL3 mutation was also found in several other family members who developed cancer and in one family member who has not been diagnosed with cancer.

Confirming that a new genetic mutation causes cancer by epidemiological approaches often requires many years of searching for similar families around the world. Therefore, the scientists turned to the zebrafish model. By recapitulating the genetic mutation in large zebrafish populations, the team could perform rapid epidemiological studies in this animal model to assess the impact of the mutation on cancer risk. Indeed, similar to individuals in the patient family, zebrafish carrying the RABL3 mutation had dramatically higher rates of cancer.

In contrast to "somatic" genetic mutations that occur during a lifetime and can cause cells to turn malignant, the mutation in RABL3 is a cancer susceptibility gene mutation that an individual is born with and that increases the risk of cancer developing later in life. Specifically, the researchers said the RABL3 mutation accelerates the movement of a known pancreatic cancer protein, KRAS, within the cell. This alteration facilitates the placement of KRAS in the cell membrane and triggers a series of events that promote cancerous growth. Because KRAS activity is altered in a majority of pancreatic cancers, continued study of the RABL3 mutation's impact on KRAS activity could provide important insights about pancreatic cancer development as well as a new strategy for targeted therapy, said the scientists. "This work highlights the power of studying and understanding rare family syndromes: from just one family, we have uncovered broadly important insights into pancreatic cancer and how we may better prevent or treat it," Dr. Nissim said.

The researchers emphasized that the RABL3 mutation is rare in the general population but said that testing for it - and potentially other mutations in the RABL3 gene - may reveal the genetic predisposition in other families with an unsolved hereditary cancer syndrome. Identifying a mutation in these families would help guide which relatives should consider pancreatic cancer screening.

"While testing for this specific genetic mutation is not available on current commercial genetic testing panels, we anticipate that the commercial tests will incorporate mutations in this gene in future panels," said Nissim, who is a physician in Dana-Farber's Cancer Genetics and Prevention Center. "We anticipate that testing for this genetic mutation will be recommended in any individual with a strong family history of pancreatic cancer."

Biologists from Hong Kong Baptist University (HKBU) have led a study to sequence and analyse the genomes of four apple snail species in the family Ampullariidae. The researchers discovered that the apple snails have evolved to become highly sensitive to environmental stimuli, digest cellulose (a major component of the plant cell wall), form hard calcareous eggshells and pack neurotoxins in eggs. The findings could facilitate the development of effective genetic control measures for these destructive crop-eating snails.

The four apple snail species are the African Lanistes nyassanus, and the South American Pomacea canaliculata, Pomacea maculata, and Marisa cornuarietis. Among them, the two Pomacea species are the most invasive. Freshwater Pomacea are widely distributed in tropical and subtropical freshwaters. These natives of South America have spread to many other parts of the world. In China, Japan, Thailand and the Philippines, they are considered the number one rice pest.

Pomacea invaded Hong Kong in the early 1980s and they are now widely distributed in various freshwater habitats in the New Territories. Though most rice paddies have been abandoned in Hong Kong, the snails found their way to vegetable gardens and damaged semiaquatic crops, especially water spinach and watercress. They have also reduced wetland biodiversity by grazing on plants and preying on animals that live at the bottom of ponds and streams.

A research team led by Professor Qiu Jianwen, Associate Head and Professor from the HKBU Department of Biology sequenced and assembled the genomes of four apple snail species. In addition to colleagues from HKBU, the team included collaborators from Hong Kong, mainland China, USA, Argentina and France.

Genome sequencing shows that apple snails have a long evolutionary history dating back more than 150 million years to the ancient continent of Gondwana. After the breakup of Gondwana roughly 100 million years ago, they have evolved separately in Africa and South America. While in Africa and South America Lanistes and Marisa have retained respectively the ancient trait of laying egg underwater, in South America Pomacea have evolved to lay their eggs on land. Comparing the African and South American apple snail species thus allowed the researchers to reveal some of the genomic innovations which have enabled Pomacea to be so invasive.

Environmental sensing and plant digestion

By comparing the genomes of apple snail species and other molluscs, the team found 28 gene families that were substantially expanded. This included some genes functionally related to chemoreception which are highly expressed in sensory tentacles, indicating that they may have enhanced environmental sensing ability.

Cellulose is the skeleton structure of green plants which helps the plant to remain stiff and strong. Different from most animals that rely on gut bacteria or fungi to break down cellulose, these apple snail species encode multiple copies of cellulase genes which enables them to secrete cellulases directly to actively decompose cellulose. This ability may help explain why apple snail species can digest a broad range of plant materials and exploit a variety of freshwater wetlands.

Formation of a hard eggshell

The research team also compared the genomes of Marisa and Lanistes, who both deposit eggs underwater, and the two Pomacea species that lay eggs on land. The ability of the amphibious Pomacea to live in water and lay eggs on land is considered a key adaptation which enables them to avoid aquatic egg predation and parasitism. To enable this dramatic change in reproduction, Pomacea eggs must be able to survive on land.

The team found that the new acquisition of a calcium binding protein (CaBP) allows Pomacea to form a hard eggshell that physically protects the egg and prevents them from drying out.

Novel defence protein

Apart from the hard eggshell, Pomacea has acquired a novel neurotoxic perivitellin called PV2 in their eggs to help defend against terrestrial predators. Previous studies have shown that PV2 is a complex of two proteins: a membrane attack complex/perforin (MACPF) that is neurotoxic, and another protein called tachylectin that binds with the predator's target cell membrane. Through comparative genomic analysis, the team found that after multiple times of duplication the gene has acquired a new function (i.e. secreting PV2 through the albumen gland). Thus gene duplication may be responsible for the origin of PV2, another key innovation which enabled the ancestors of Pomacea to move from laying eggs underwater to on land.

Implications

Since Ampullariidae is an early diverging family of Caenogastropoda, one of the species of molluscs and the most diverse group of which accounts for over 60% of all gastropod species, the genomes of apple snail species are ideal for comparative studies with other molluscs, for which only a few published genomes are available.

Professor Qiu said: "The genomic data discovered by the team is a valuable resource for understanding ancestral genomic features within the ecologically important and biologically diverse caenogastropods. Given that several invasive apple snail species are notorious agricultural pests, the genomic resources from this study can be used to develop effective control strategies, including the synthesis of chemical molluscicides and the design of genetic control measures using ribonucleic acid (RNA) interference."

ANN ARBOR--Asian carp are capable of surviving and growing in much larger portions of Lake Michigan than scientists previously believed and present a high risk of becoming established, according to a new modeling study from University of Michigan researchers and their colleagues.

Some previous studies suggested that low food levels in Lake Michigan could be a barrier to the establishment of bighead and silver carp, which typically feed on algae and other types of plankton. Bighead and silver carp are the two Asian carp species of greatest concern for the Great Lakes.

But earlier studies did not consider the fact that bighead and silver carp are opportunistic feeders capable of surviving on a wide variety of diets, including dead organic matter called detritus. In Lake Michigan, detritus includes bits of resuspended fecal pellets from countless quagga and zebra mussels on the lake bottom.

In addition, previous studies did not evaluate potential carp habitat more than a meter below the lake's surface.

When diet flexibility and subsurface habitat were factored in, the amount of suitable Asian carp habitat in Lake Michigan increased dramatically, according to study lead author Peter Alsip, who conducted the research for his master's thesis at U-M's School for Environment and Sustainability.

At certain times of year, the model showed that the entire extent of Lake Michigan, which has a surface area of more than 22,000 square miles and an average depth of 280 feet, contains suitable bighead carp habitat somewhere in the water column, according to Alsip, who now works at the U-M-based Cooperative Institute for Great Lakes Research.

Silver carp habitat was confined to nearshore, nutrient-rich areas. The study's findings are scheduled for publication Aug. 12 in the journal Freshwater Biology.

"Subsurface habitat and the fishes' diet flexibility were not evaluated in previous studies, and our findings indicate that these considerations had a noticeable effect on our suitability assessment," Alsip said. "Lake Michigan's low supply of plankton may not be as strong a barrier as previously thought."

The study also found that:

Allowing the fish to feed on the broadest possible diet (phytoplankton, zooplankton and detritus) throughout the water column resulted in suitable habitat volumes that were 4.6 times greater than the narrowest diet (phytoplankton only) for bighead carp and 2.3 times greater for silver carp.

While the extent of high-quality Asian carp habitat across Lake Michigan is relatively small, the risk of localized establishment events is high near river mouths and in nutrient-rich parts of Green Bay. The team's model found suitable year-round habitat (which other models suggest is capable of supporting spawning and egg development) near the mouths of several rivers, including the Milwaukee and St. Joseph.

Maps generated by the team's model identified Asian carp establishment hot spots and the potential for cross-lake migration corridors "that may facilitate and accelerate lake-wide movements," the authors wrote. Those maps could aid surveillance efforts by identifying areas to which bighead and silver carp might spread upon entering the lake.

The relatively plankton-rich "deep chlorophyll layer" that forms each summer in offshore Lake Michigan waters is capable of supporting bighead carp growth. Previous carp studies did not evaluate growth potential in this layer, which forms at an average depth of about 100 feet.

Levels of plankton-supporting nutrients in Lake Michigan have been declining for decades, largely due to reduced levels of phosphorus entering the lake and the spread of invasive quagga and zebra mussels, which now blanket the lake bottom, sucking up plankton and sequestering nutrients in fecal pellets called biodeposits.

The progressive loss of nutrients in Lakes Michigan's water column, a process called oligotrophication, has generated skepticism among some scientists around the likelihood of Asian carp establishment there. But laboratory experiments have demonstrated that Asian carp are capable of surviving--and even gaining weight--while feeding only on quagga mussel biodeposits.

In their study, Alsip and his colleagues used simulated food abundance and water temperature values from a three-dimensional biophysical model of Lake Michigan to study the growth rate potential of bighead and silver carp.

They looked at how well individual adults of the two carp species could grow in Lake Michigan when feeding on various combinations of the three food types--phytoplankton, zooplankton and detritus--at various depths. Areas where bighead and silver carp could either maintain or increase their body weight were classified as suitable habitat.

"We found that suitable habitat for bighead carp is widespread in Lake Michigan, and that's a result of fundamental ecological importance for many reasons," said study co-author Hongyan Zhang of Eureka Aquatic Research in Ann Arbor. Zhang, formerly of U-M's School for Environment and Sustainability and the Cooperative Institute for Great Lakes Research, was Alsip's thesis adviser.

Phytoplankton are single-celled, photosynthetic algae and cyanobacteria. Zooplankton are tiny animals at the base of the food chain that feed on phytoplankton. A big concern about Asian carp is that they might outcompete resident plankton-eating fish, including the larval stages of most fish species.

The new study showed that the widespread availability of quagga mussel fecal pellets in Lake Michigan would likely help keep Asian carp alive, enabling them to migrate through plankton-depleted open waters and eventually spreading throughout the lake. Bighead and silver carp are collectively known to scientists as bigheaded carp, or BHC.

"The ability of BHC to flexibly feed on phytoplankton, zooplankton and detritus mitigates their risk of starvation--even in offshore waters--and, therefore, increases their probability of establishment," according to the authors. "Therefore, it seems likely that BHC could survive, establish, and spread to favorable habitat in Lake Michigan and its tributaries despite having to travel across expansive areas with minimal plankton biomass."

Bighead and silver carp were imported to the Southern United States in the 1970s to control algae growth in reservoirs and sewage-treatment lagoons. They escaped and quickly spread throughout the Mississippi River Basin, establishing dense populations in places like the Illinois River, where they now comprise 63% of the total weight of all fish in the river.

Currently, bighead and silver carp are established in watersheds close to the Great Lakes but not in the lakes themselves.

The impact of Asian carp on already invaded ecosystems, as well as the proximity of the invasion front to Lake Michigan, have elevated concerns about the potential invasion of the Great Lakes via the Chicago Area Waterway System, the man-made connection between the Illinois River and Lake Michigan.

In May, the head of the U.S. Army Corps of Engineers sent Congress a $778 million plan to install carp defenses at the Brandon Road Lock and Dam near Joliet, Illinois, about 40 miles from Lake Michigan. In July, the region's eight U.S. governors and two Canadian premiers endorsed the plan.

The Freshwater Biology study is titled "Lake Michigan's Suitability for Bigheaded Carp: The Importance of Diet Flexibility and Subsurface Habitat." DOI: 10.1111/fwb.13382.

In addition to Alsip and Zhang, other authors are Mark Rowe, Doran Mason and Edward Rutherford of the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory in Ann Arbor; Catherine Riseng of the U-M School for Environment and Sustainability and Michigan Sea Grant; and Zhenming Su of the Michigan Department of Natural Resources.

The project was funded by the Michigan Sea Grant Graduate Research Fellowship, with matching funds provided by the Institute for Fisheries Research at the Michigan Department of Natural Resources. Additional support was provided by Michigan Sea Grant, the Institute for Fisheries Research, CIGLR, GLERL and the Great Lakes Aquatic Non-indigenous Species Information System.

Using the same approach described above, Alsip and colleagues are currently studying how Asian carp habitat suitability is affected by meteorology, lakewide phosphorus loads, and quagga and zebra mussels. Their findings could provide a clearer picture of how a warming climate will affect Lake Michigan's vulnerability to Asian carp and how habitat suitability has changed over time in response to nutrient-load reductions and the mussel invasion.

Like the eponymous character in Shel Silverstein's classic children's tale, trees are generous with their gifts, cleaning the air we breathe and slowing the ravages of global warming by absorbing about a quarter of all human-caused carbon dioxide emissions. But this generosity likely can't last forever in the face of unabated fossil fuel consumption and deforestation. Scientists have long wondered whether trees and plants could reach a breaking point and no longer adequately absorb carbon dioxide.

An international team led by scientists at Stanford University and the Autonomous University of Barcelona finds reason to hope trees will continue to suck up carbon dioxide at generous rates through at least the end of the century. However, the study published Aug. 12 in Nature Climate Change warns that trees can only absorb a fraction of carbon dioxide in the atmosphere and their ability to do so beyond 2100 is unclear.

"Keeping fossil fuels in the ground is the best way to limit further warming," said study lead author César Terrer, a postdoctoral scholar in Earth system science in Stanford's School of Earth, Energy & Environmental Sciences. "But stopping deforestation and preserving forests so they can grow more is our next-best solution."

Weighing carbon dioxide

Carbon dioxide - the dominant greenhouse gas warming the earth - is food for trees and plants. Combined with nutrients like nitrogen and phosphorus, it helps trees grow and thrive. But as carbon dioxide concentrations rise, trees will need extra nitrogen and phosphorus to balance their diet. The question of how much extra carbon dioxide trees can take up, given limitations of these other nutrients, is a critical uncertainty in predicting global warming.

"Planting or restoring trees is like putting money in the bank," said co-author Rob Jackson, the Michelle and Kevin Douglas Provostial Professor in Earth System Science at Stanford. "Extra growth from carbon dioxide is the interest we gain on our balance. We need to know how high the interest rate will be on our carbon investment."

Several individual experiments, such as fumigating forests with elevated levels of carbon dioxide and growing plants in gas-filled chambers, have provided critical data but no definitive answer globally. To more accurately predict the capacity of trees and plants to sequester carbon dioxide in the future, the researchers synthesized data from all elevated carbon dioxide experiments conducted so far - in grassland, shrubland, cropland and forest systems - including ones the researchers directed.

Using statistical methods, machine-learning, models and satellite data, they quantified how much soil nutrients and climate factors limit the ability of plants and trees to absorb extra carbon dioxide. Based on global datasets of soil nutrients, they also mapped the potential of carbon dioxide to increase the amount and size of plants in the future, when atmospheric concentrations of the gas could double.

Their results show that carbon dioxide levels expected by the end of the century should increase plant biomass by 12 percent, enabling plants and trees to store more carbon dioxide - an amount equivalent to six years of current fossil fuel emissions. The study highlights important partnerships trees forge with soil microbes and fungi to help them take up the extra nitrogen and phosphorus they need to balance their additional carbon dioxide intake. It also emphasizes the critical role of tropical forests, such as those in the Amazon, Congo and Indonesia, as regions with the greatest potential to store additional carbon.

"We have already witnessed indiscriminate logging in pristine tropical forests, which are the largest reservoirs of biomass in the planet," said Terrer, who also has a secondary affiliation with the Institut de Ciencia i Tecnologia Ambientals, Universitat Autonoma de Barcelona. "We stand to lose a tremendously important tool to limit global warming."

Neutron stars are not only the most dense objects in the Universe, but they rotate very fast and regularly.

Until they don't.

Occasionally these neutron stars start to spin faster, caused by portions of the inside of the star moving outwards. It's called a "glitch" and it provides astronomers a brief insight into what lies within these mysterious objects.

In a paper published today in the journal, Nature Astronomy, a team from Monash University, the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav), McGill University in Canada, and the University of Tasmania, studied the Vela Pulsar, a neutron star in the southern sky, that is 1,000 light years away.

According to the paper's first author, Dr Greg Ashton, from the Monash School of Physics and Astronomy, and a member of OzGrav, Vela is famous - not only because only 5% of pulsars are known to glitch but also because Vela "glitches" about once every three years, making it a favourite of "glitch hunters" like Dr Ashton and his colleague, Dr Paul Lasky, also from Monash and OzGrav.

By reanalysing data from observations of the Vela glitch in 2016 taken by co-author Dr Jim Palfreyman from the University of Tasmania, Dr Ashton and his team found that during the glitch the star actually started spinning even faster, before relaxing down to a final state.

According to Dr Lasky, an ARC Future Fellow also from the Monash School of Physics and Astronomy, and a member of OzGrav this observation (done at the Mount Pleasant Observatory in Tasmania) is particularly important because, for the first time, the scientists got a glimpse into the interior of the star - revealing that the inside of the star actually has three different components.

"One of these components, a soup of superfluid neutrons in the inner layer of the crust, moves outwards first and hits the rigid outer crust of the star causing it to spin up," Dr Lasky said.

"But then, a second soup of superfluid that moves in the core catches up to the first causing the spin of the star to slow back down.

This overshoot has been predicted a couple of times in the literature, but this is the first real time it's been identified in observations," he said.

One such prediction of the overshoot came from study co-author Dr Vanessa Graber from McGill University, who visited the Monash team as an OzGrav international visitor earlier this year.

Another observation, according to Dr Ashton, defies explanation.

"Immediately before the glitch, we noticed that the star seems to slow down its rotation rate before spinning back up," Dr Ashton said.

"We actually have no idea why this is, and it's the first time it's ever been seen.

"It could be related to the cause of the glitch, but we're honestly not sure," he said adding that he suspects this new paper to inspire some new theories on neutron stars and glitches.

Recent studies into the relationship between decreases in sea ice in the Arctic and ice-cold winters in the mid-latitudes, like the Polar Vortex cold waves in North America, seem to suggest that such a connection does indeed exist. However, the mechanisms behind this relationship have remained unclear so far, mainly due to the chaotic nature of the climate system. This has changed with the publication of an article in Nature Climate Change, with honorary Professor Richard Bintanja from the University of Groningen as one of the co-authors.

This article uses for the first time a very extensive set of climate data produced by two detailed climate models; including the KNMI climate model EC-Earth. The large amount of climate data enabled the authors to make statistical connections that were previously hidden in the noise of the climate system.

Analysis of the model data shows that relatively cold winters and Arctic sea ice decline occur at the same time, but that one does not cause the other. Both changes appear to be the result of a completely different mechanism, namely large-scale anomalies in atmospheric circulation. An important supportive finding of this study is that both climate models come to exactly the same conclusion. Also, a simulation with sea ice decrease imposed does not lead to cold winters at all.

Professor Richard Bintanja: "The findings in our article show that a further decrease in Arctic sea ice in the near future will most likely not lead to more and intense wintry cold waves, because episodes with little Arctic sea ice are the result of unusual atmospheric circulation patterns, and not the cause."

Bottom Line: An analysis of claims data for privately insured patients suggests out-of-network billing for inpatient admissions and emergency department (ED) visits to in-network hospitals has increased along with the patient financial liability associated with it. This study included 5.4 million inpatient admissions and nearly 13.6 million ED visits to in-network hospitals between 2010-2016. Of all the ED visits, 39.1% generated an out-of-network bill and 37% of all the inpatient admissions resulted in an out-of-network bill. The percentage of ED visits with an out-of-network bill increased from 32.3% to 42.8% during the study period and the percentage of inpatient admissions with an out-of-network bill increased from 26.3% to 42% during that same time.  The potential patient financial responsibility associated with out-of-network bills increased too, from an average $220 to $628 for ED visits and from an average $804 to $2,040 for inpatient admissions. A common example of out-of-network billing was ambulance transport. This study has some limitations, including no information on what patients actually paid to settle out-of-network bills. Researchers suggest their findings support strengthening legislative protections against the surprise medical bills associated with out-of-network billing.

Authors: Eric Sun, M.D., Ph.D., of Stanford University Medical Center in Stanford, California, is the corresponding author.

(doi:10.1001/jamainternmed.2019.3451)

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.

Cybersecurity researchers have discovered vulnerabilities in the backend systems that feed content and advertising to smartphone applications through a network of cloud-based servers that most users probably don't even know exists.

In research to be reported August 15 at the 2019 USENIX Security Symposium, researchers from the Georgia Institute of Technology and The Ohio State University identified more than 1,600 vulnerabilities in the support ecosystem behind the top 5,000 free apps available in the Google Play Store. The vulnerabilities, affecting multiple app categories, could allow hackers to break into databases that include personal information - and perhaps into users' mobile devices.

To help developers improve the security of their mobile apps, the researchers have created an automated system called SkyWalker to vet the cloud servers and software library systems. SkyWalker can examine the security of the servers supporting mobile applications, which are often operated by cloud hosting services rather than individual app developers.

"A lot of people might be surprised to learn that their phone apps are communicating with not just one, but likely tens or even hundreds of servers in the cloud," said Brendan Saltaformaggio, an assistant professor in Georgia Tech's School of Electrical and Computer Engineering. "Users don't know they are communicating with these servers because only the apps interact with them and they do so in the background. Until now, that has been a blind spot where nobody was looking for vulnerabilities."

The Air Force Office of Scientific Research and the National Science Foundation supported the research.

In their study, the researchers discovered 983 instances of known vulnerabilities and another 655 instances of zero-day vulnerabilities spanning across the software layers - operating systems, software services, communications modules and web apps - of the cloud-based systems supporting the apps. The researchers are still investigating whether attackers could get into individual mobile devices connected to vulnerable servers.

"These vulnerabilities affect the servers that are in the cloud, and once an attacker gets on the server, there are many ways they can attack," Saltaformaggio said. "It's a whole new question whether or not they can jump from the server to a user's device, but our preliminary research on that is very concerning."

The researchers identified three types of attack that could be made on the backend servers: SQL injection, XML external entity and cross-site scripting, explained Omar Alrawi, a Georgia Tech graduate research assistant and co-first author with Chaoshun Zuo at Ohio State. By taking control of these machines in the cloud, attackers could gain access to personal data, delete or alter information or even redirect financial transactions to deposit funds in their own accounts.

To study the system, Alrawi and Zuo ran applications in a controlled environment on a mobile device that connected to backend servers. They then watched the communications between the device and servers, and repeated the process for all of the applications studied.

"We found that a lot of applications don't encrypt the communications between the mobile app and the cloud service, so an attacker that is between the two points or on the same network as the mobile could get information about the user - their location and user name - and potentially execute password resets," Alrawi said.

The vulnerabilities were not easy to spot. "You have to understand the context through which the app communicates with the cloud server," he said. "These are very deep bugs that cannot be identified by simply scanning and using traditional tools that are used for web application security."

The operators of vulnerable systems were notified of the findings. Concerns about who is responsible for securing those backend servers is one of the issues to come out of the study.

"It's actually a significant problem because of how many different software developers may have their hands in building these cloud servers," Saltaformaggio said. "It's not always clear who is responsible for doing the patching and who is responsible for the vulnerabilities. It's tough to track down these vulnerabilities, but it's also tough to get them patched."

To save app developers from having to do the security research they did, the researchers are offering SkyWalker, an analysis pipeline to study mobile backends. Developers will be able to submit their apps to SkyWalker at (https://mobilebackend.vet) and get a report on what it finds.

"SkyWalker will watch how the application communicates with those cloud servers, and then it will try to communicate with the servers to find vulnerabilities," said Alrawi. "This information can give an app developer a heads-up about potential problems before they make their application public."

The researchers studied only applications in the Google Play Store. But applications designed for iOS may share the same backend systems.

"These servers provide backend services for mobile apps that any device could use," Alrawi said. "These cloud services are essential components of modern mobile apps. They are part of the always-connected world."

For the future, the researchers hope to study how the vulnerabilities could affect smartphone users, and to check on whether the problems they identified have been addressed.

"We are going to keep doing these sorts of studies and will revisit them later to see how the attack landscape has improved," said Saltaformaggio. "We will keep looking for more blind spots that need to be studied. In the new world of smartphones and mobile applications, there are unique problems that need to be rooted out."