Earth

Cells consist of a multitude of molecular structures, some of them exhibiting a staggering complexity. Ribosomes, the protein factories of the cell, belong to the biggest and most sophisticated complexes and are made up of RNA as well as a large number of proteins. They exist in every living being and are considered as one of the cellular machines that has changed the least through all stages of the evolution. But there are exceptions: In mitochondria, cellular organelles that serve as power plants, ribosomes look considerably different.

An extensive machinery

Scientists are not only interested in the structure and function of such ribosomes, but also in the "construction process" - how do cells manage the assembly of these complex structures? And how do these construction methods differ, for different structures? It is clear that an extensive cellular machinery is needed to guarantee for a smooth assembly of all the building bricks. This cellular machinery responsible for ribosome assembly in mitochondria has not been described yet. Now, researchers from the André Schneider group of the University of Bern and the Nenad Ban group of ETH Zurich, investigated the mitochondrial ribosome assembly process using the unicellular parasite Trypanosoma brucei. They were able to follow the construction process and to identify the associated cellular machinery dedicated to assemble these mitoribosomes. Since T. brucei causes hardly treatable diseases including sleeping sickness, the results could lead to new therapies. The project was made possible by the National Center of Competence in Research "RNA & Disease", which studies the role of RNA in disease mechanisms. The findings have now been published in "Science".

Unknown elements in the "construction business"

The parasite Trypanosoma brucei was used as a model system since its mitoribosomes are particularly complex and, therefore, likely to require many assembly steps. The researchers could follow all these steps in detail. "We have found fascinating differences", says Moritz Niemann from the Department of Chemistry and Biochemistry of the University of Bern, co-author. In mitochondrial ribosomes RNA can be considered as the steel in reinforced concrete, whereas in other ribosomes it can be considered to play key structural role as in iron-based structures such as the Eiffel Tower. Analysis showed that the assembly of mitoribosomes in T. brucei proceeds through the formation of several assembly intermediates. It also involves a large number of proteins that form a huge adaptive scaffolding around the emerging mitoribosome that is not present in the completed structure. Martin Saurer from the Department of Biology of ETH Zurich and first author, says that many of these proteins were unknown in the "construction business". "Cryo-electron microscopy does not only allow us to visualize known complexes but also to discover and describe an entire cellular process: the construction site and the machinery involved in assembling mitochondrial ribosomes," he adds. Moritz Niemann was especially baffled by the enormous effort the cell is putting into this: "Up to a quarter of all proteins in the mitochondrion are components of the mitoribosomes or are required to build them."

Better understanding leads to new therapies

Since several of the assembly proteins have look-alikes in other organisms, the researchers believe that the obtained insights provide general information for better understanding ribosomal maturation in all organisms. And because all these proteins are essential for the functioning of the cell, these findings could be useful for developing therapies against T. brucei and related parasites that cause many devastating diseases in humans and animals.

RNA & Disease - The Role of RNA Biology in Disease Mechanisms

The NCCR &laquoRNA & Disease - The Role of RNA Biology in Disease Mechanisms» studies a class of molecules that has long been neglected: RNA (ribonucleic acid) is pivotal for many vital processes and much more complex than initially assumed. For instance, RNA defines the conditions, in a given cell, under which a given gene is or is not activated. If any part of this process of genetic regulation breaks down or does not run smoothly, this can cause heart disease, cancer, brain disease and metabolic disorders.The NCCR brings together Swiss research groups studying different aspects of RNA biology. By researching which regulatory mechanisms are dysregulated in disease, the NCCR discovers new therapeutical targets. Leading institution is the University of Bern, with the ETH Zurich co-leading. National Centers of Compentence in Research are a research instrument of the Swiss National Science Foundation (SNSF).
https://nccr-rna-and-disease.ch/

NASA has the unique capability of peering under the clouds in storms and measuring the rate in which rain is falling. Global Precipitation Measurement mission or GPM core satellite passed over Tropical Storm Jerry from its orbit in space and measured rainfall rates throughout the storm.

The GPM's core satellite passed over Tropical Storm Jerry in the Atlantic Ocean on Sept. 18 at 11:51 p.m. EDT (Sept. 19 at 0351 UTC). GPM found the heaviest rainfall stretching from the eastern to southern side of the storm where it was falling at a rate of over 25 mm (about 1 inch) per hour there and in a fragmented band of thunderstorms west of center. Forecasters at NOAA's National Hurricane Center or NHC incorporate the rainfall data into their forecasts.

Hurricanes are the most powerful weather event on Earth. NASA's expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

NHC issued a Tropical Storm Watch for Barbuda, Anguilla, St. Maarten, St. Martin, St. Barthelemy, Saba and St. Eustatius.

At 8 a.m. EDT (1200 UTC), the center of Tropical Storm Jerry was located near latitude 16.4 degrees north and longitude 53.9 degrees west. That puts Jerry's center about 525 miles (845 km) east of the Leeward Islands. Jerry is moving toward the west-northwest near 16 mph (26 kph). A west-northwest motion at a slightly faster forward speed is expected over the next few days.

Maximum sustained winds remain near 70 mph (110 kph) with higher gusts. Jerry is forecast to become a hurricane later today, with little change in strength anticipated on Friday or Saturday. The estimated minimum central pressure is 995 millibars.

NHC noted in its key messages that "Jerry is expected to become a hurricane before it moves close to the northern Leeward Islands Friday. Although the core of Jerry is currently expected to pass north of the islands, tropical-storm-force winds and locally heavy rainfall are possible, and tropical storm watches have been issued for a portion of this area." Additional key messages for Jerry can be found on the web at: http://www.hurricanes.gov/text/MIATCDAT5.shtml.

Researchers from North Carolina State University have shown that the E75 protein is a key regulator of some biological rhythms through interactions with nitric oxide. Suppression of E75 results in longer molt cycles and reduced numbers of offspring in the water flea, Daphnia magna. The work also raises questions about the ability of nitric oxide from environmental sources to disrupt biological rhythms that are critical to population sustainability.

Gerald LeBlanc, professor of biology at NC State and corresponding author of a paper describing the work, was interested in the role that environmental cues played in regulating biological rhythms using Daphnia magna as a model organism.

Daphnia magna, or the common water flea, is a crustacean found in most freshwater ponds in North America. The water flea is not only a keystone species - important for the maintenance of food webs in these ecosystems - it is also a lab model for crustaceans more generally.

"We are looking at how biological rhythms regulate physiological processes," LeBlanc says. "How does an organism know when to molt? Or when to migrate? Many rhythms are based on environmental cues; for example, our own circadian - or sleep cycle - is based in part on experiencing light and dark. But are there similar environmental cues that regulate longer rhythms - and if so, what effect might environmental stressors have on them?"

LeBlanc and his team targeted a protein, E75, known to play a role in regulating some biological rhythms. Nitric oxide, a short-lived hormone and potent signaling molecule, inhibits E75's activity. The researchers exposed daphnids to the nitric oxide-generating compound sodium nitroprusside, which disrupted the molecular cascade that leads to molting and increased the length of the molt cycle. They then established that direct suppression of E75 using RNA interference produced similar results. Not only did suppression of E75 lengthen the molt cycle but it also reduced the number of offspring produced.

"Water fleas produce nitric oxide naturally," LeBlanc says, "but they can also take up nitrogenous compounds from their surroundings and convert them into nitric oxide. E75 is the first domino in the molt cycle, and a critical regulator of molting and reproduction, since they are coordinated in water flea. We show that nitric oxide can disrupt the rhythm, thereby disrupting growth, time to reproductive maturation and fecundity. The consequences of such a disruption over time could be devastating to the population.

"We also know that the molt cycle is regulated by environmental cues. It is possible that nitric oxide is the environmental modulator, in which case environmental sources of nitrogen - such as fertilizer runoff - could fool the animal and disrupt the population. These are questions we would like to explore in the future."

In a crystal, atoms are highly ordered, occupying well-defined locations that form spatial patterns. Seven years ago, the 2004 Physics Nobel laureate Frank Wilczek pondered the possibility of a 'time analogue of crystalline spatial order' - systems that display sustained periodic temporal modulations in their lowest-energy state. The concept of such structures with an oscillating ground state is highly intriguing. Alas, not long after the idea has been published, it was proven that such time crystals are not possible without breaking fundamental laws of physics. Not all was lost, though. Subsequent theory work suggested that when quantum many-body systems are periodically driven, then new persistent time correlations emerge that are evocative of Wilczek's time crystals. These driven systems were dubbed 'discrete time crystals', and in 2017 the first experimental realizations of such states were reported in ensembles of coupled particles (ions, electrons and nuclei) that display quantum-mechanical properties.

A not-so-brief history of time crystals

Before long, astute observers spotted distinct similarities between discrete time crystals in quantum systems and so-called parametric resonators, a concept in classical physics reaching back to work by Michael Faraday in 1831. The connection between these two bodies of work remained, however, opaque. Now, a new framework goes a long way towards lifting the ambiguities surrounding the similarities between periodically driven classical and quantum systems. Writing in an article published today in the journal Physical Review Letters, Toni Heugel, a PhD student in the Department of Physics at ETH Zurich, and Matthias Oscity, a Master student there, working with Dr. Ramasubramanian Chitra and Prof. Oded Zilberberg form the Institute for Theoretical Physics and with Dr. Alexander Eichler from the Laboratory for Solid State Physics, report theoretical and experimental work that establishes how discrete time crystals can be generated that, on the one hand, require no quantum mechanical effects and, on the other hand, display genuine many-body effects, which is a characteristic of discrete time crystals reported in quantum systems.

Many ways to subharmonic frequencies

There is one obvious similarity between classical parametric resonators and experimentally realized discrete time crystals in quantum many-body systems: Both display emergent dynamics at frequencies that are fractions of the drive frequency. In the context of discrete time crystals, the emergence of oscillations at such subharmonic frequencies breaks the temporal periodicity of the driven system, providing a form of 'time analogue' to crystalline spatial order, where the symmetry of space is broken. In classical parametrically driven systems, subharmonic frequencies appear in more familiar ways: A child on a swing, for instance, modifies the centre of gravity at twice the frequency of the resulting oscillation; or the ponytail of a runner oscillates at half the frequency of the vertical head movement.

But do these dissimilar phenomena have anything to do with one another? Yes, say the ETH physicists. In particular, they pinpoint where many-body aspects appear in classical systems. To do so, they considered classical nonlinear oscillators with tunable coupling between them.

Unifying framework for periodically driven classical and quantum systems

It is well known that for certain driving frequencies and strengths, parametric oscillators become unstable and then undergo a so-called period-doubling bifurcation, beyond which they oscillate at half their driving frequency. Heugel, Oscity and their colleagues explore what happens as several such oscillators are coupled together. In calculations as well as in experiments -- using two strings with variable coupling between them -- they find two distinct regimes. When the coupling is strong, the two-string system moves collectively, recreating in essence the movements of the child on a swing or the ponytail of a runner. However, in the case of weak coupling between the strings, the dynamics of each string is close to that displayed by the uncoupled system. As a consequence, the coupled oscillators do not bifurcate collectively but bifurcate individually at slightly different parameters of the drive, leading to richer overall dynamics, which gets ever more complex as the systems get larger.

The ETH researchers argue that such weakly-coupled modes are similar to the ones that emerge in quantum many-body systems, implying that their framework might explain the behaviours seen experimentally in these systems. Moreover, the new work prescribes general conditions for generating classical many-body time crystals. These could ultimately be used to both interpret and explore features of their quantum counterparts.

Taken together, these findings therefore provide a powerful unifying framework for periodically driven classical and quantum systems displaying dynamics at emergent subharmonic frequencies -- systems that have been so far described in very different contexts, but might be not that dissimilar after all.

Since they first arrived on land, plants have likely been using the same genetic tools to regulate whether they grow bigger or reproduce. The discovery was made using liverwort, one descendant of the first plants to move out of the ancient oceans and onto land.

Liverworts grow all over the world and resemble moss, spreading on moist soil under some shade. Male and female versions of liverwort are recognized by unique, umbrella-shaped structures that shoot up from the base of the plant.

"Liverworts have the maximum power with the least structure," said Professor Yuichiro Watanabe from the University of Tokyo's Department of Life Sciences, an expert in plant molecular biology.

The liverwort genome is structurally simple compared to the flowering plants that are commonly used in research laboratories, like tobacco and thale cress (Arabidopsis). Flowering plants are evolutionarily "younger" plants than liverworts, with gene duplications and redundancies that make studying their genomes more complicated.

Despite that simplicity, the liverwort genome appears to have all the same life-cycle stages and powers to regulate them.

Genome similarities

The entire genome of the liverwort species Marchantia polymorpha was first sequenced in 2017 by an international team, which included several researchers who also participated in the recently published gene analysis.

When they examined the full genome, researchers discovered that even the simple liverwort has about 100 different types of a small molecule, called microRNA, which regulate the activity of other genes.

About eight of the liverwort microRNAs were nearly identical to known thale cress microRNAs. These eight microRNAs fascinated researchers because the ancestral plants that evolved into modern liverworts and modern thale cress split over 450 million years ago.

"So, why keep them? We want to know what those shared microRNAs are doing, and liverworts are now a convenient model for us to investigate," said Watanabe.

To get bigger or to reproduce

Most mammals, including humans, are born with the cells that they'll need as adults to produce their own offspring. Plants, however, develop their reproductive cells only after switching from the vegetative stage, when they grow new leaves or get bigger, to the reproductive stage.

One of the microRNAs that helps flowering plants control the shift to the reproductive stage is also one of the eight microRNAs shared between thale cress and liverworts. That microRNA is known to researchers as microRNA156/529.

To pin down the potential role of this evolutionarily conserved microRNA, Watanabe's research group created a genetically modified version of liverwort that lacked microRNA156/529. Those so-called microRNA156/529 knockout liverworts produced reproductive cells on their vegetative tissues rather than developing the normal umbrella-shaped reproductive structures that distinguish males and females.

"This was amazing to us. Those liverworts skipped some part of the reproductive process and the body itself becomes the reproductive organ," said Watanabe.

Identifying the same molecule with a similar role in the vegetative-to-reproductive switch in such different plant species reveals that microRNA156/529 and the other molecules it interacts with are part of an important control module used by potentially all land plants to regulate their reproductive timing.

Watanabe imagines that in the future, farmers could measure the amount of microRNA156/529 in crops to predict harvest times.

"We hope our results inspire others to develop new applications for plant reproduction," said Watanabe.

For long-distance transportation within the cell, RNA molecules rely on hitchhiking.

A microscopic RNA molecule might need to travel as far as a meter to get from the nucleus of a nerve cell to its tip, where it's needed to make a protein. But exactly how RNA gets around has been "a long-standing question in the field" - and one with big implications for how cells work, says Jennifer Lippincott-Schwartz, a senior group leader at the Howard Hughes Medical Institute's Janelia Reseach Campus.

Now, she and her colleagues, including co-senior author Michael Ward at the National Institute of Neurological Disorders and Stroke, have found one explanation: RNA molecules hitch a ride on structures called lysosomes, best known for their role as cellular recycling centers, the team reports September 19, 2019, in the journal Cell.

This transit might go awry in people with the neurodegenerative disease amyotrophic lateral sclerosis (ALS), the work suggests.

RNA transportation is a key part of keeping a cell functioning properly. RNA carries instructions for building proteins. Often, it's dispatched to wherever the protein it codes for is needed, then translated into a protein on-site. So if RNA isn't distributed around a cell correctly, key proteins might not end up in the right places. That's a particularly big deal in large cells like neurons.

In a healthy neuron, RNA molecules cluster together with proteins to form "granules," packets of RNA that can be ferried around more easily than individual RNA strands. Then, a protein called Annexin A11 works like a power adaptor, Lippincott-Schwartz, Ward, and their colleagues showed. It can latch onto both standard membrane-bound organelles, like lysosomes, and membraneless structures, like the RNA granules.

Lysosomes easily zip around the cell. The adaptor protein allows RNA to take advantage of lysosomes' mobility and plug into a transportation network that would otherwise be inaccessible.

People with ALS often have mutations in the gene for Annexin A11, says Lippincott-Schwartz. Now, it's becoming clear how these mutations affect patients. When her team introduced mutations into the protein that mimic those seen in ALS patients, the RNA granules couldn't attach to the lysosomes. And if RNA can't get a ride to the places where it's needed to make proteins, neurons might have trouble either surviving or signaling properly to other cells.

In theory, RNA granules could hitchhike on any number of organelles. But lysosomes make sense for a few reasons, says study lead author Ya-Cheng Liao, an associate at Janelia. They're already highly mobile, moving around the cell to clean up trash. And they can pull double duty: Once the RNA has been deposited at its destination to be translated, the lysosome can perform its traditional function of taking up and digesting molecules from its surroundings.

"You can think of this paper as defining a new function for lysosomes," says Lippincott-Schwartz.

Next, the researchers plan to investigate whether other proteins might work like Annexin A11, and how the RNA granules form and disassemble.

CAMBRIDGE, MA -- People who are accustomed to listening to Western music, which is based on a system of notes organized in octaves, can usually perceive the similarity between notes that are same but played in different registers -- say, high C and middle C. However, a longstanding question is whether this a universal phenomenon or one that has been ingrained by musical exposure.

This question has been hard to answer, in part because of the difficulty in finding people who have not been exposed to Western music. Now, a new study led by researchers from MIT and the Max Planck Institute for Empirical Aesthetics has found that unlike residents of the United States, people living in a remote area of the Bolivian rainforest usually do not perceive the similarities between two versions of the same note played at different registers (high or low).

The findings suggest that although there is a natural mathematical relationship between the frequencies of every "C," no matter what octave it's played in, the brain only becomes attuned to those similarities after hearing music based on octaves, says Josh McDermott, an associate professor in MIT's Department of Brain and Cognitive Sciences.

"It may well be that there is a biological predisposition to favor octave relationships, but it doesn't seem to be realized unless you are exposed to music in an octave-based system," says McDermott, who is also a member of MIT's McGovern Institute for Brain Research and Center for Brains, Minds and Machines.

The study also found that members of the Bolivian tribe, known as the Tsimane', and Westerners do have a very similar upper limit on the frequency of notes that they can accurately distinguish, suggesting that that aspect of pitch perception may be independent of musical experience and biologically determined.

McDermott is the senior author of the study, which appears in the journal Current Biology on Sept. 19. Nori Jacoby, a former MIT postdoc who is now a group leader at the Max Planck Institute for Empirical Aesthetics, is the paper's lead author. Other authors are Eduardo Undurraga, an assistant professor at the Pontifical Catholic University of Chile; Malinda McPherson, a graduate student in the Harvard/MIT Program in Speech and Hearing Bioscience and Technology; Joaquin Valdes, a graduate student at the Pontifical Catholic University of Chile; and Tomas Ossandon, an assistant professor at the Pontifical Catholic University of Chile.

Octaves apart

Cross-cultural studies of how music is perceived can shed light on the interplay between biological constraints and cultural influences that shape human perception. McDermott's lab has performed several such studies with the participation of Tsimane' tribe members, who live in relative isolation from Western culture and have had little exposure to Western music.

In a study published in 2016, McDermott and his colleagues found that Westerners and Tsimane' had different aesthetic reactions to chords, or combinations of notes. To Western ears, the combination of C and F# is very grating, but Tsimane' listeners rated this chord just as likeable as other chords that Westerners would interpret as more pleasant, such as C and G.

Later, Jacoby and McDermott found that both Westerners and Tsimane' are drawn to musical rhythms composed of simple integer ratios, but the ratios they favor are different, based on which rhythms are more common in the music they listen to.

In their new study, the researchers studied pitch perception using an experimental design in which they play a very simple tune, only two or three notes, and then ask the listener to sing it back. The notes that were played could come from any octave within the range of human hearing, but listeners sang their responses within their vocal range, usually restricted to a single octave.

Western listeners, especially those who were trained musicians, tended to reproduce the tune an exact number of octaves above or below what they heard, though they were not specifically instructed to do so. In Western music, the pitch of the same note doubles with each ascending octave, so tones with frequencies of 27.5 hertz, 55 hertz, 110 hertz, 220 hertz, and so on, are all heard as the note A.

Western listeners in the study, all of whom lived in New York or Boston, accurately reproduced sequences such as A-C-A, but in a different register, as though they hear the similarity of notes separated by octaves. However, the Tsimane' did not.

"The relative pitch was preserved (between notes in the series), but the absolute pitch produced by the Tsimane' didn't have any relationship to the absolute pitch of the stimulus," Jacoby says. "That's consistent with the idea that perceptual similarity is something that we acquire from exposure to Western music, where the octave is structurally very important."

The ability to reproduce the same note in different octaves may be honed by singing along with others whose natural registers are different, or singing along with an instrument being played in a different pitch range, Jacoby says.

Limits of perception

The study findings also shed light on the upper limits of pitch perception for humans. It has been known for a long time that Western listeners cannot accurately distinguish pitches above about 4,000 hertz, although they can still hear frequencies up to nearly 20,000 hertz. In a traditional 88-key piano, the highest note is about 4,100 hertz.

People have speculated that the piano was designed to go only that high because of a fundamental limit on pitch perception, but McDermott thought it could be possible that the opposite was true: That is, the limit was culturally influenced by the fact that few musical instruments produce frequencies higher than 4,000 hertz.

The researchers found that although Tsimane' musical instruments usually have upper limits much lower than 4,000 hertz, Tsimane' listeners could distinguish pitches very well up to about 4,000 hertz, as evidenced by accurate sung reproductions of those pitch intervals. Above that threshold, their perceptions broke down, very similarly to Western listeners.

"It looks almost exactly the same across groups, so we have some evidence for biological constraints on the limits of pitch," Jacoby says.

One possible explanation for this limit is that once frequencies reach about 4,000 hertz, the firing rates of the neurons of our inner ear can't keep up and we lose a critical cue with which to distinguish different frequencies.

Jacoby and McDermott now hope to expand their cross-cultural studies to other groups who have had little exposure to Western music, and to perform more detailed studies of pitch perception among the Tsimane'.

Such studies have already shown the value of including research participants other than the Western-educated, relatively wealthy college undergraduates who are the subjects of most academic studies on perception, McDermott says. These broader studies allow researchers to tease out different elements of perception that cannot be seen when examining only a single, homogenous group.

"We're finding that there are some cross-cultural similarities, but there also seems to be really striking variation in things that a lot of people would have presumed would be common across cultures and listeners," McDermott says. "These differences in experience can lead to dissociations of different aspects of perception, giving you clues to what the parts of the perceptual system are."

In a new study, researchers at Uppsala University have identified a previously unknown mechanism that regulates release of insulin, a hormone that lowers blood glucose levels, from the β-cells (beta cells) of the pancreas. This mechanism is disrupted in type 2 diabetes. The scientists hope this finding will be used to develop new treatments against the disease.

Globally, more than 400 million people suffer from type 2 diabetes. One of the main problems is inadequate secretion, from the β-cells of the pancreas, of insulin hormone, which lowers blood sugar (blood glucose).

It has been known for some time that impaired insulin secretion is due to an inability of the insulin-containing secretory granules attach themselves ('dock') to, and then fuse with, the cell membrane. As a result, less insulin reaches the blood and, accordingly, the body becomes less able to reduce blood glucose levels sufficiently.

In the new study, the scientists identify a protein, Sac2, that is found at lower levels in patients with type 2 diabetes. In experiments, the researchers show that lowering the levels of this protein by experimental means leads to reduced insulin secretion from the β-cells. By using advanced microscopy techniques, the researchers were able to show that Sac2 is an important component on the surface of the insulin-containing secretory granules, where it modifies the fat composition of the membrane. In the absence of Sac2, a specific fat molecule accumulates on the surface of the secretory granules. This incapacitates them, so that they cannot dock to the cell membrane, which in turn causes insulin secretion to be reduced.

This study shows, first and foremost, that reduced levels of a single protein gives rise to β-cells that exhibit several defects associated with type 2 diabetes. But it also shows that the fat composition of the insulin-containing secretory granules is of importance for their ability to be released from the cells. The scientists now hope that it will be possible to use these findings to develop new ways of treating type 2 diabetes.

Per- and polyfluoroalkyl substances (PFAS) are building up in the environment, and scientists are becoming concerned. These substances, ubiquitous as water-repellent or nonstick additives in many consumer products, are persistent and have been accumulating in organisms throughout the food chain over many years. Now, researchers reporting in the ACS journal Environmental Science & Technology have identified bacteria from a New Jersey wetland that, surprisingly, can break carbon-fluorine bonds and degrade PFAS.

The carbon-fluorine (C-F) covalent bond is the strongest in organic chemistry, and until now, no organism was known to be capable of breaking it. In previous work, Shan Huang and Peter Jaffé isolated a bacterium, called Acidimicrobiaceae sp. A6 (A6), from the soil of New Jersey wetlands that could perform an unusual chemical reaction: using iron in the soil to help break down ammonium, a pollutant found in sewage and fertilizer runoff, without any oxygen. Huang and Jaffé wondered if this reaction, called Feammox, could also help break down PFAS.

To find out, the researchers grew cultures of A6 in iron- and ammonium-rich medium and added one of two PFAS: perfluorooctanoic acid (PFOA) or perfluorooctane sulfonate (PFOS). The team found that A6 used the Feammox reaction to transfer electrons from ammonium or hydrogen gas to PFAS, removing the fluoride atoms and rendering the substances harmless. As a result, over a 100-day period, the microbes degraded up to 60% of the PFOA and 50% of the PFOS added to the cultures. These results indicate that under appropriate environmental conditions, A6 and the Feammox process could biodegrade PFAS in contaminated soil and groundwater, the researchers say.

Prior research has shown that immigrants have lower rates of offending, arrest, and incarceration than nonimmigrants. However, that work hasn't examined whether this holds true for recidivism. A new study compared recidivism rates of foreign-born and native-born individuals formerly incarcerated for felonies and released from prisons in Florida. It found that immigrants are significantly less likely to reoffend by committing another felony than their nonimmigrant peers.

The study, by researchers at Florida State University, appears in Justice Quarterly, a publication of the Academy of Criminal Justice Sciences.

"In concluding that immigrants reoffend at a lower rate than their nonimmigrant peers, our study continues to dispel the myth of the criminal immigrant," explains Marin R. Wenger, assistant professor in the College of Criminology and Criminal Justice at Florida State University, who coauthored the study. "Our findings suggest that policymakers and others should ignore the heated rhetoric directed toward foreign-born individuals and, in a time of limited resources, focus on groups for which reducing recidivism would translate into safer communities rather than focusing on immigrants."

Using data from the Florida Department of Corrections, the study compared recidivism rates of 192,556 immigrants and nonimmigrants formerly incarcerated for felonies and released from Florida prisons between 2004 and 2011. Of the total, 188,677 were nonimmigrants and 3,879 were immigrants. Researchers found that 32% of nonimmigrants were reconvicted of a felony offence within three years of release, compared to only 19% of immigrants. Recidivism was defined as reconviction for a felony offence with a new sentence imposed within three years of release.

To determine whether differences in rates of recidivism between the two groups could be accounted for by other factors associated with criminality, the study took into account participants' gender, age, race and ethnicity, prior felony convictions and most recent felony conviction, and whether the individual had been labeled a habitual offender in Florida. It also considered participants' prior violations while under supervision; the number of times they were committed to prison; and whether they had a high school diploma, were married, or were employed when they were incarcerated. And it took into account in which judicial circuit the participants were sentenced and their year of release.

Researchers used a variety of methods to assess the link between immigration status and recidivism. While they found that the time to recidivism among those reconvicted was similar for the two groups--19.5 months for immigrants and 19.3 months for nonimmigrants--they also found that nonimmigrants were more likely to be reconvicted than immigrants, even after taking into account the abovementioned factors. This result held when they repeated their analyses measuring time to recidivism with one, two, and five years.

The authors acknowledge that because their study was restricted to individuals who served time in Florida prisons and were released to a county in Florida, the findings may not be generalizable to other U.S. states. And because their measure of recidivism was restricted to reconviction for a felony offense, results may not be generalizable to other measures of recidivism, like re-arrest.

"Given the current political and social climate and the demand among some legislators for more exclusionary immigration policies, our study is important because it shows that immigrant ex-inmates pose a smaller risk to the community than nonimmigrant ex-inmates," says Javier Ramos, a doctoral candidate at Florida State University, who coauthored the study.

One of the ways NASA researches tropical cyclones is using infrared data that provides temperature information. The AIRS instrument aboard NASA's Aqua satellite captured a look at those temperatures in Tropical Depression Imelda and gave insight into the storm's rainfall potential over eastern Texas.

Cloud top temperatures provide information to forecasters about where the strongest storms are located within a tropical cyclone. Tropical cyclones do not always have uniform strength, and some sides have stronger sides than others. The stronger the storms, the higher they extend into the troposphere, and they have the colder cloud temperatures.

NASA provides data to forecasters at NOAA's National Hurricane Center or NHC so they can incorporate in their forecasting.

On Sept. 17 at 3:41 p.m. EDT (1541 UTC) NASA's Aqua satellite analyzed the storm using the Atmospheric Infrared Sounder or AIRS instrument. AIRS found coldest cloud top temperatures as cold as or colder than minus 63 degrees Fahrenheit (minus 53 degrees Celsius) north and east of Imelda's center. NASA research has shown that cloud top temperatures that cold indicate strong storms that have the capability to create heavy rain. Some of the heaviest rain at the time of the image was over the Texas coastline.

Forecasters incorporated the insight into rainfall potential into their forecasts. On Sept. 18, as Imelda moved slowly to the north, heavy rains and significant flash flooding were spreading inland over eastern Texas and are expected during the next couple of days.
NOAA's National Weather Service (NWS) Weather Prediction Center (WPC) in College Park, Md. posted, "Flash flood watches were in effect for southeast Texas and extreme southwest Louisiana."

That heavy rainfall potential is in the forecast from the NWS WPC: Imelda is expected to produce the following rainfall amounts through Friday [Sept. 20]: Across the Upper Texas Coast into eastern Texas, including the Houston and Galveston areas...additional 5 to 10 inches. Isolated storm totals of 20 to 25 inches. Across portions of southwest Louisiana...4 to 8 inches with isolated totals of 10 inches. These rainfall totals may produce significant to life threatening flash floods.

At 11 a.m. EDT (1500 UTC), NWS said the center of Tropical Depression Imelda was located near latitude 30.6 degrees north and longitude 95.6 degrees west. The depression is moving toward the north near 5 mph (7 km/h) and this motion is expected to continue through tonight. Maximum sustained winds are near 30 mph (45 kph) with higher gusts. Little change in strength is forecast during the next 48 hours. The estimated minimum central pressure is 1009 millibars.

Hurricanes are the most powerful weather event on Earth. NASA's expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

The AIRS instrument is one of six instruments flying on board NASA's Aqua satellite, launched on May 4, 2002.

For updated forecasts, visit: http://www.nhc.noaa.gov

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ANN ARBOR--The rate at which the planet warms in response to the ongoing buildup of heat-trapping carbon dioxide gas could increase in the future, according to new simulations of a comparable warm period more than 50 million years ago.

Researchers at the University of Michigan and the University of Arizona used a state-of-the-art climate model to successfully simulate--for the first time--the extreme warming of the Early Eocene Period, which is considered an analog for Earth's future climate.

They found that the rate of warming increased dramatically as carbon dioxide levels rose, a finding with far-reaching implications for Earth's future climate, the researchers report in a paper scheduled for publication Sept. 18 in the journal Science Advances.

Another way of stating this result is that the climate of the Early Eocene became increasingly sensitive to additional carbon dioxide as the planet warmed.

"We were surprised that the climate sensitivity increased as much as it did with increasing carbon dioxide levels," said first author Jiang Zhu, a postdoctoral researcher at the U-M Department of Earth and Environmental Sciences.

"It is a scary finding because it indicates that the temperature response to an increase in carbon dioxide in the future might be larger than the response to the same increase in CO2 now. This is not good news for us."

The researchers determined that the large increase in climate sensitivity they observed--which had not been seen in previous attempts to simulate the Early Eocene using similar amounts of carbon dioxide--is likely due to an improved representation of cloud processes in the climate model they used, the Community Earth System Model version 1.2, or CESM1.2.

Global warming is expected to change the distribution and types of clouds in the Earth's atmosphere, and clouds can have both warming and cooling effects on the climate. In their simulations of the Early Eocene, Zhu and his colleagues found a reduction in cloud coverage and opacity that amplified CO2-induced warming.

The same cloud processes responsible for increased climate sensitivity in the Eocene simulations are active today, according to the researchers.

"Our findings highlight the role of small-scale cloud processes in determining large-scale climate changes and suggest a potential increase in climate sensitivity with future warming," said U-M paleoclimate researcher Christopher Poulsen, a co-author of the Science Advances paper.

"The sensitivity we're inferring for the Eocene is indeed very high, though it's unlikely that climate sensitivity will reach Eocene levels in our lifetimes," said Jessica Tierney of the University of Arizona, the paper's third author.

The Early Eocene (roughly 48 million to 56 million years ago) was the warmest period of the past 66 million years. It began with the Paleocene-Eocene Thermal Maximum, which is known as the PETM, the most severe of several short, intensely warm events.

The Early Eocene was a time of elevated atmospheric carbon dioxide concentrations and surface temperatures at least 14 degrees Celsius (25 degrees Fahrenheit) warmer, on average, than today. Also, the difference between temperatures at the equator and the poles was much smaller.

Geological evidence suggests that atmospheric carbon dioxide levels reached 1,000 parts per million in the Early Eocene, more than twice the present-day level of 412 ppm. If nothing is done to limit carbon emissions from the burning of fossil fuels, CO2 levels could once again reach 1,000 ppm by the year 2100, according to climate scientists.

Until now, climate models have been unable to simulate the extreme surface warmth of the Early Eocene--including the sudden and dramatic temperature spikes of the PETM--by relying solely on atmospheric CO2 levels. Unsubstantiated changes to the models were required to make the numbers work, said Poulsen, a professor in the U-M Department of Earth and Environmental Sciences and associate dean for natural sciences.

"For decades, the models have underestimated these temperatures, and the community has long assumed that the problem was with the geological data, or that there was a warming mechanism that hadn't been recognized," he said.

But the CESM1.2 model was able to simulate both the warm conditions and the low equator-to-pole temperature gradient seen in the geological records.

"For the first time, a climate model matches the geological evidence out of the box--that is, without deliberate tweaks made to the model. It's a breakthrough for our understanding of past warm climates," Tierney said.

CESM1.2 was one of the climate models used in the authoritative Fifth Assessment Report from the Intergovernmental Panel on Climate Change, finalized in 2014. The model's ability to satisfactorily simulate Early Eocene warming provides strong support for CESM1.2's prediction of future warming, which is expressed through a key climate parameter called equilibrium climate sensitivity.

The term equilibrium climate sensitivity refers to the long-term change in global temperature that would result from a sustained doubling--lasting hundreds to thousands of years--of carbon dioxide levels above the pre-industrial baseline of 285 ppm. The consensus among climate scientists is that the ECS is likely to be between 1.5 C and 4.5 C (2.7 F-8.1 F).

The equilibrium climate sensitivity in CESM1.2 is near the upper end of that consensus range at 4.2 C (7.7 F). The U-M-led study's Early Eocene simulations exhibited increasing equilibrium climate sensitivity with warming, suggesting an Eocene sensitivity of more than 6.6 C (11.9 F), much greater than the present-day value.

Risk of compound flooding, which can result when rapid sea level rises associated with storms occur along with heavy rains, is currently concentrated along Mediterranean countries but will greatly increase for Northern European in the future as the climate warms, according to a new modeling study. This is the first study of compound flooding to consider future changes that could result from combined geographic shifts in precipitation, storm surges, waves and tides. The hazard of compound flooding is not usually included in coastal flooding risk analyses, even though storm surges and extreme precipitation runoff are related. What's more, coastal cities are expected to further grow in the coming decades, underscoring an urgent need to assess future compound flooding probability - which other analyses have overlooked. E. Bevacqua et al. modeled the probability of high sea levels and heavy precipitation occurring simultaneously along European coasts both in the present and under a future business-as-usual climate change scenario. Assuming a warmer future climate, the researchers found the probability of compound flooding risk is likely to increase heavily along the west coast of Great Britain, northern France, the east and south coast of the North Sea, and the eastern half of the Black Sea. The Bristol Channel and the Devon and Cornwall coast in the UK, as well as the Dutch and German North Sea coast, are considered hot spots, with compound flooding events likely to occur more than once every six years. The threat is even worse near Noorderzijlvest in the Netherlands, where the compound flooding risk is expected to triple, and around Bergen on the Norwegian coast, where it may increase by fivefold.

In 2018, breast cancer was the most common cancer in women worldwide, accounting for about a quarter of all reported cancers. One of the biggest problems with any type of cancer is metastasis; and when breast cancer metastasizes, the brain is a common destination.

The prevalence of breast-to-brain metastases has led scientists to suspect that there is an underlying rationale for why breast cancer cells seek out and seed tumor growths in the brain. Elucidating the rationale might give us the means to minimize breast-to-brain metastases or even prevent them altogether.

Publishing in Nature, scientists at EPFL's Swiss Institute for Experimental Cancer Research (ISREC) have discovered that this process involves the "N-methyl-D-aspartate receptor" (NMDAR), which is found on the cell membranes of neurons and is involved in the transmission of nerve impulses. The NMDAR is activated by the amino acid glutamate, released from pre-synaptic neurons during synaptic transmission of such impulses.

The ISREC group has shown in the past that glutamate-stimulated NMDAR signaling helps both neuroendocrine and ductal pancreatic tumors grow invasively, and that this co-opted neuronal signaling circuit is generally associated with a poor treatment prognosis in a variety of cancer types. So when the researchers began looking for suspects in breast-to-brain metastases, the NMDAR was at the top of the list.

The investigation paid off: The researchers grew breast-to-brain metastasis cells in the lab to study their relationship to the NMDAR. And, sure enough, the cells were found to co-opt the entire system by which the NMDAR relays its effects to neurons - what biologists refer to as a "signaling pathway".

It seems then that a key to metastasizing to the brain involves turning on the NMDAR. Although some cancer cells secrete sufficient glutamate to auto-activate NMDAR, the current study found that it's not sufficient in breast cancer cells. So, how might they activate the NMDAR receptor?

In a breakthrough discovery, the researchers found that the breast cancer cells form "fake" synapses with the neurons that normally secrete glutamate as a neurotransmitter. The synapse is "pseudo-tripartite" because it resembles the tripartite synapse between two neurons and the surrounding non-neuronal, supporting cells (e.g. astrocytes).

Once the synapses are formed, the neurons supply the breast-cancer cells with ample glutamate, and the NMDAR receptor turns on, providing what the authors call "an insidious rationale for brain metastasis".

"This remarkable mechanism for fueling the growth of metastatic tumors in the brain adds to an expanding knowledge base about the parameters of metastasis that we hope will be applicable to prevention and therapy," says Douglas Hanahan. "The challenge is the insidious proximity of the cancer cells to normal neuronal synapses, for which NMDAR signaling is crucial. Thus, in future research, we and others will need to search for specific vulnerabilities in glutamate-fueled metastatic breast cancer cells that can be targeted therapeutically to block brain metastasis, while sparing the adjacent normal neurons."

What The Study Did: This study examined the association of adverse childhood experiences and caregiver support with the development of regions of the brain in childhood and adolescence. The analysis included 211 children who had neuroimaging and behavioral assessments conducted during preschool and adolescence. Magnetic resonance imaging (MRI) measured changes in volume of specific regions of the brain. Preschool and school-age adverse childhood experiences and caregiver support were assessed.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamanetworkopen.2019.11426)

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.