Lab Notes

Rising global temperatures are one of the biggest threats to biodiversity. The slow creep up of the thermometer — 1.2 degrees Celsius over the past 150 years — is blisteringly fast on a geological timescale, and species can only adapt so fast. But they’ve evolved to deal with changing temperatures in the past — sometimes, very far in the past. Scientists writing in Nature earlier this year found that considering this “memory” of climate history helps better predict extinction risks as the planet continues to heat up.

The researchers tracked thousands of animal extinctions through the fossil record and compared their frequencies under different prehistoric combinations of long- and short-term temperature changes. If a rapid change in temperature was preceded by a slower temperature change in the opposite direction, the rapid change was usually less deadly. They presume this occurs because the second change returns to distant-past temperatures for which species remained fit, after timescales as long as 60 million years. On the other hand, rapid temperature changes in the same direction as a previous slower change were especially risky.

The effect of prior long-term temperature is strong enough to seriously impact predictions of extinction risk for any given group of species. According to their results, it changes the risk calculation as much as its geographic range or abundance. And, while even the “short-term” prehistoric extinctions happened over timescales far slower than today’s maelstrom of extinction, long-term temperature effects provide a bit of hope: The rapid warming of the Anthropocene was preceded by a long global cooling period, which could make climate change a little less deadly.

Neural networks, a type of machine learning algorithm that work similarly to the way our brains so, are bad at dealing with inputs that are different to what they’ve seen before. Facial recognition algorithms, for example, often fail to recognize the faces of Black people, typically because the algorithms were trained on mostly white faces.

The same can happen with tumor detection. When training a neural network to detect tumors in MRI scans, differences between the scanner setups at each hospital mean that a neural network trained and proficient with data from one hospital performs worse on scans made somewhere else.

One approach to making a more generally useful network is to penalize it for learning information that you’re not interested in. In a study published in the journal NeuroImage, researchers trained their network by rewarding it for identifying tumors correctly and penalizing it for being able to guess which hospital the scan was from. This arrangement pushed the network to learn ways to identify tumors without relying on scanner signatures specific to any one hospital. When they compared their network to a similar one without this technique, their network did much better on scans from new locations than the old network did.

This technique can be used to make neural networks that work better on new data that is different from the data they saw during training. This has the potential to improve the usefulness of neural networks for real life medical diagnosis assistance.

In humans and some animals, long periods of physical inactivity can lead to osteoporosis, a disease where bones break down and become weak. Osteoporosis is usually caused by either bone not being formed or an increase in bone resorption (where components of bone are reabsorbed into the body). But bears are inactive for 4-6 months of the year during their winter hibernation periods, yet they do not develop osteoperosis. New research, published in Scientific Reports, explores how black bears manage to escape this fate. 

During hibernation, black and grizzly bears (Ursus americanus and Ursus arctos horribilis) are known to decrease their metabolic rates by about 20-75 percent to save energy, relying solely on fat stores as their energy source. This new study shows that when bears reduce their metabolism, genes involved in bone resorption become less active. Additionally, there is no increase in the gene expression associated with bone formation or osteoblasts (cells that make bones). The researchers also found evidence of that genes involved with energy production from bone and bone marrow become more active during hibernation, which may provide the bears with an additional energy source during fasting.

In the last decade, we've learned so much about the microbial organisms living in our gut. The bacteria in our guts play important roles across our body, including digestion, stress signaling, and immune function. Despite exciting findings in rats and mice, few of these findings have translated to humans thus far. 

Nonetheless, research on the dietary fibers that these microbes feed on is yielding exciting results. These fibers cannot be broken down by our enzymes. Only our gut bacteria can digest them. In the process, the bacteria generate byproducts that interact with our nervous systems. Past research has shown that these byproducts reduced perceived stress in men. Now, a new study finds that galacto-oligosaccharide (GOS) fibers also reduce perceived anxiety in healthy women.

Nicola Johnstone of the University of Surrey and her colleagues designed a double-blind, placebo-controlled trial. Johnstone recruited 48 women (ages 18-25) to provide poop samples and undergo psychological testing. The participants were assessed in the beginning of the experiment. Then, for four weeks, they ingested either a small packet containing GOS or a placebo. After, they participated again in the same psychological tests. 

At both time points, the researchers collected samples for microbiome analysis. They also conducted questionnaires to assess the participants' moods before and after the intervention, and measured their and attention through the psychological tests. During these four weeks, all the participants kept a food diary.

The participants who took GOS showed a small increase in the growth of the gut bacterium Bifidobacterium, which feeds on these fibers. When Johnstone and her team analyzed the impact of GOS on anxiety, they found that GOS reduced self-reported anxiety in women with high-baseline anxiety. Women that had a low anxiety score at baseline did not experience a further reduction even in the GOS group. GOS did not associate with any other psychological measures or changes.

If you have ever traveled from the center of a big city to a rural area, or the other way around, one of the starkest contrasts is the change in air quality. Although there have been significant decreases in emissions recently, there are still regions where peaks of air pollution are reported. Leaving the climate catastrophe caused by burning fossil fuels aside for a minute, scientists have recently found that these pollutants also have a direct toll on our brains. 

Take for instance black carbon, a material emitted from gas and diesel engines and coal-fired power plants, and also one of the components of fine particulate matter (PM2.5). In both children and adults, exposure to this pollutant has been associated with poor cognitive abilities over the years. What Xu Gao and their colleagues discovered and demonstrated in a new paper, however, is that even short exposures can also cause significant declines in cognition.

The researchers were part of the Normative Aging Study, a cohort of older men from the greater Boston area. Alongside daily measurements of the levels of both PM2.5 and black carbon, over the period of 28 days, the team conducted two tests on 954 participants: the global cognitive function and Mini-Mental State Examination. They found that higher short-term exposure to PM2.5 reduced scores on both tests, and that even small concentrations of PM2.5 had a large effect. The effects of pollution were less for participants who used nonsteroidal anti-inflammatory drugs such as ibuprofen than for those who did not. 

While we already knew that air pollution has many different adverse effects on our health, this is the first time scientists have shown how these effects can manifest in short-term exposures, to relatively small concentrations of pollutants.

Sandwiched inside your laptop, at the back of your smartphone, and under the hood of your dream electric car are powerful and lightweight lithium-ion batteries. Even though these batteries are found inside the technology we use every day, they are rarely recycled — which means that the valuable metals inside them are not recovered for reuse.

Researchers at Texas A&M wanted to build a battery that would be lightweight and powerful, like lithium-ion batteries, but that would be more easily recyclable. To do this, they did something that had never been done before: they built electrodes, which transfer electrical charges in and out of a battery, with degradable polymers instead of metals. Their results appear in the journal Nature.

The researchers chose polymers called polypeptides because these polymers break apart into their building blocks, amino acids, when heated with just the right amount of acid. Polypeptides are not inherently conductive, though, so the researchers chemically modified them by attaching structural units that can transfer electrons back and forth. They then built electrodes by mixing the polypeptides with carbon black, another conductive material, and a binding material to hold everything together. 

After successfully charging and draining the new batteries up to 250 times, the researchers disassembled the batteries and broke the polypeptide electrodes down into amino acids and other small molecule building blocks that could be reused to re-build battery electrodes later. Although the polypeptide batteries didn’t perform quite as well as traditional lithium-ion batteries, they are an exciting alternative because the energy storing materials inside them were easily recovered. By degrading on-demand, these batteries could pave the way as a new class of recyclable batteries for the technology that we use every day.

When was the last time you had something bitter? The more bitter the food is, the less you probably want to eat it. And we are fortunate because of that — throughout the course of evolution, bitter sensations have kept humans away from potentially dangerous food or toxic molecules.

A similar sensory ability has also been detected in other animals such as rodents and Drosophila flies. While rodents have somewhat similar bitter taste receptors to humans, flies possess what are known as bitter-sensitive neurons located in their taste organ. But, similar to most animals, once the receptor is activated by contact with a bitter chemical, an aversive reaction is induced, and the flies stop eating the bitter food. Scientists have even observed that insects will willingly starve just to avoid the noxious compounds, skewing results of studies that involve feeding bitter food to flies.

Recently, researchers at Shoolini University of Biotechnology and Management Sciences in India published a method to trick flies into eating bitter compounds. They encapsulate these appalling molecules inside donut-shaped molecular cages known as cucurbiturils (CB). In the study, researchers prepared tweaked mixtures of caffeine and strychnine, a highly toxic pesticide commonly used for rodents, by confining them inside the molecule “CB7” – cucurbiturils formed by seven repeating units. As predicted, the flies found these masked compounds more palatable and were more willing to feed on CB7-caged caffeine and strychnine molecules.

Being able to feed insects using this method opens up a new area of exploration in elucidating flies’ taste experience on bitter food, as well as the relationship between bitter molecules and toxicity.

 This Lab Note is also available in English. 

Los humanos modificamos nuestros alrededores como mejor nos parece. Somos capaces de eliminar cualquier animal, desde un caracol inconveniente en el jardín hasta un lobo con la costumbre de matar ganado. No es de extrañar que los animales nos tengan miedo.

Pero los efectos de ese miedo se hacen notar más allá de los animales. Los animales son criaturas adaptables. Se adaptan a nuestros horarios y comportamientos modificando los suyos propios. Y estos cambios en sus comportamientos tienen consecuencias. Los efectos ecológicos de estos cambios se extienden hasta los grandes carnívoros, como los pumas.

Los pumas viven a lo largo de las Américas, desde la Patagonia en el sur hasta las regiones sub-árticas de Canadá. Pero la mayoría de la gente que vive en esos lugares pasará todas sus vidas sin ver a un solo puma. Ellos saben cómo evitarnos, y los animales que suelen ser presas de los pumas lo han notado.

Un nuevo artículo publicado en la revista científica Ecosphere ha encontrado que los ciervos de cola negra en las montañas de Santa Cruz de California están pasando más tiempo en las áreas del bosque más cercanas a la habitación humana. Y no es porque las plantas allí sean de mejor calidad o sepan mejor, o porque los humanos les estén dando de comer. Es porque los pumas están asustados de acercarse a estas áreas donde hay gente en las cercanías, y por ello evitan ir a esas áreas.

Los pumas están pasando tanto tiempo en esas áreas de los bosques que los están modificando. Las plantas en estas áreas se están volviendo más arbustivas, ya que los ciervos están básicamente podando las plantas. Esto, a su vez, crea más comida para los ciervos, creando un escenario ideal para los ciervos. Necesitamos más investigación para saber cómo estos cambios afectan a otros animales en estas áreas, como los pájaros o los insectos, pero el efecto indirecto que la presencia de los humanos ha causado en el paisaje está claro.

In every “Things you need to buy from Amazon!” list, you will almost always find one item: blue light-blocking glasses. At the height of the COVID-19 pandemic, we irradiated our eyes with blue light — by staring at smartphones, televisions, and computers far more often and for longer periods than we did during pre-pandemic times. Suddenly, people started eyeing light-blocking glasses to reduce eye strain. But do these glasses actually help, or are they just a scam?

At first glance, whittling down our exposure to blue light makes scientific sense. Blue light is critical in maintaining our circadian rhythms, which are the natural cycles our body goes through in a 24-hour period that dictate waking and sleeping. But timing is key in the way blue light controls our bodies. During the day, blue light activates the parts of our brain required for attention; at night, however, it blocks the production of melatonin, a molecule that induces sleep, and increases alertness.

This is why some researchers have used blue light-blocking glasses to see whether they can improve sleep quality. Studies have found that blue light-blocking glasses improved sleep in people with Parkinson’s disease, delayed sleep disorder, and insomnia. In fact, the use of blue light glasses promotes advanced sleep onset and melatonin production, suggesting that they could indeed be helpful in regulating sleep. 

However, this may not hold for individuals without sleep disturbances. An analysis of many studies found that blue light-blocking glasses did not improve sleep quality for the general population. It’s possible that these glasses only benefit individuals who already have some type of sleep disorder.

Furthermore, blue light glasses can't reduce digital eye strain — characterized by dry eyes, headaches, and blurred vision —  because it has nothing to do with blue light exposure. Mark Rosenfield, one of the researchers who debunked such advertising of glasses sellers, suggests instead taking breaks often and increasing the viewing distance to reduce digital eye strain. 

Whether blue light-blocking glasses help the rest of the population and how still remain to be studied. So, while these glasses may improve sleep quality for some, it will be just as necessary to reduce our exposure to digital devices as much as we can. So, if you need an excuse to decline yet another Zoom meeting, consider your eyes! 

Exposure to smoke in the areas around wildfire-prone forests is known to exacerbate respiratory and cardiovascular disease. However, surprisingly little is known about the exact mechanism by which this occurs. This is in part due to the complex nature of chemical reactions that occur as forests burn: Plants and trees are sophisticated living systems, and when they are subjected to the massive amount of heat in a fire, chemical reactions run wild, creating a myriad of combustion products. 

Shedding light on this issue requires tracking not just individual chemicals but the interplay between mixtures of chemicals. For example, chemical X might affect our lungs in one way by itself but in another way when accompanied by chemical Y. In a new study published in Science of the Total Environment, environmental scientists from the University of North Carolina analyzed the smoke of five commonly burned biomass components (eucalyptus, peat, pine, pine needles, and red oak). They identified at least 86 different chemicals that could be released when those materials burn.

By tracking the relationships between these chemicals, the researchers discovered that the degree of toxicity of wildfire smoke depends on the type of biomass being burned, with pine being one of the least harmful. This is primarily due to the presence of a class of molecules called methoxyphenols, including vanillin (which gives vanilla its flavor). Even when harmful inorganic or ionic components like lead, chlorine, or phosphates were present in high amounts, methoxyphenols acted as protective agents, suppressing the negative effects. This can be helpful not only to identify which people living nearby are most at risk based on the composition of nearby biomass, but also to give clues to how adverse effects could be mitigated by a mindful selection of trees for reforestation.

It’s widely believed that the now-undeniable therapeutic properties of psilocybin, the chemical found in magic mushrooms, are due to its hallucinogenic, consciousness-warping properties. Psilocybin and other psychedelics are extremely effective in treating a host of neurological conditions, from clinical depression to migraine  —  just one dose can make people feel less depressed for up to six months. 

But the features that make magic mushrooms a popular recreational drug (the six-plus hours of visual hallucinations, the altered state of consciousness), lower its clinical usability. Essentially, though psilocybin is largely benign, patients need to be observed and counseled for their trips. But contrary to conventional wisdom, or what your very chill, Burning man-going friend will tell you, the altered consciousness state may not be necessary for the beneficial effects of psilocybin.

 A recent study published in the journal PNAS showed that psilocybin still decreases depressive symptoms in mice even when it’s delivered alongside a drug that prevents psilocybin’s hallucinatory effects.  This means that in the future, people may be able to reap the beneficial effects of psilocybin from the comforts of their own homes — without things getting weird. 

Predator-prey interactions are like an arms race, with both parties trying to one up each other to survive. Animals have developed many ingenious ways to escape predation, such as by startling, confusing, or actively repelling their predators.

Typically, when an animal notices its predator lurking around, it either pauses its routine to run away from the predator or tries a defensive tactic to ward it off. That is why scientists were puzzled to see what fruit flies (Drosophila melanogaster) do when predatory wasps are nearby: they increase their mating. This finding is detailed in a new paper published in Nature Communications. 

Since wasps specifically target fruit fly larvae, the accelerated mating made no sense to the researchers. They started by checking whether the increased mating was a result of changes in male or female flies or a combination of both. To resolve this, they paired off females and males exposed to wasps with both exposed and unexposed partners. It turned out that, wasp exposure was making only the female flies more interested in mating — males exposed to wasps weren’t observed to be more interested than unexposed males. Turning their focus solely on the females, researchers then used mutant fly strains with impaired hearing and vision to confirm that seeing the wasp was essential for heightened mating response. 

These initial observations led the researchers to question the nature of the response to wasps — was it immediate or lasting? They introduced a gap of two hours between wasp-exposure and mating, to test out the possible timespan of this response. They saw that the response was indeed temporary. Exposed flies mated as usual if enough time elapsed after being around the wasps.

Upon comparing gene expression profiles of wasp-exposed and non-exposed flies, researchers were able to identify ten genes that showed high expression levels only in wasp-exposed flies. Among them, the IBIN gene showed highest increase. When they gave flies a mutated copy of IBIN gene, those flies didn't show that accelerated mating behavior near wasps. 

The researchers propose that female flies probably prioritize successful mating over finding a suitable mate, because they anticipated the additional effort required for finding a safe egg-laying sites when surrounded by the wasps.

The Chernobyl nuclear disaster of 1986 exposed millions of Ukrainian people to high levels of ionizing radiation. This type of radiation is known to increase DNA mutation rates and animal studies have suggested that parents exposed to ionizing radiation produce offspring who have higher-than-normal levels of DNA mutations. However, whether this occurs in humans has remained largely unknown. Studies that have tried to answer this question before have lacked sufficiently large sample sizes and defined radiation exposure levels in the parents to answer the question conclusively. 

A new study published in Science is the largest ever, and the first to sequence the entire genomes of parent/children trios to determine the full impact of radiation exposure on the next generation. Researchers interviewed Ukrainian parents about their exposure in the wake of the Chernobyl disaster and calculated cumulative radiation dose estimates for each person. They then sequenced DNA samples from over 100 exposed parent/child trios and calculated the parents' mutation rates, as well as the number of new mutations in the children. According to their analysis, there is no relationship between the number of new mutations in children's DNA and radiation exposure level of their parents. 

The finding comes as a relief for victims of the Chernobyl accident, and brings much needed hope to others who have experienced nuclear disasters. Survivors of nuclear incidents have not only suffered debilitating health consequences, but intense stigma from their communities. Women in particular have been shunned by potential partners due to fears that their children would inherit genetic defects, and in the immediate wake of the disaster it is estimated that tens of thousands of women intentionally terminated their pregnancies due to this same fear. The results of this study are therefore incredibly significant for the individuals and communities that have been ravaged by man-made nuclear disasters.

“Spatially resolved transcriptomics” was the “Method of the Year 2020” according to Nature Methods. But what is this technology, and what can we do with it? A recent study from the Lieber Institute for Brain Development provides an example.

First, a thin slice of biological tissue is placed on a specialized microscope slide. The tissue slice is photographed under the microscope. RNA molecules within the tissue are captured and sequenced to measure gene expression. The microscope photo helps determine which genes were expressed in specific parts of the tissue slice, revealing how gene expression varies across the tissue.

The approach is suitable for studying the human brain, especially the cerebral cortex which is organized into well-defined layers. Each layer has its own specific types of cells with a distinctive shape, molecular identity, and connectivity with the rest of the brain. Earlier studies measured the gene expression in layers of the cortex one gene at a time. In contrast, the recent study from the Lieber Institute measured layer-specific expression across all expressed genes, called the “transcriptome”.

Using brain tissue from three donors, the researchers measured gene expression across the layers of the prefrontal cortex – a brain region implicated in psychiatric and neurological diseases. They confirmed the previously described layer-specific expression pattern of several genes and identified additional genes which also show a layered pattern of expression. Further, the researchers found layer-specific expression of genes linked with schizophrenia and autism, a finding that could enhance our understanding of the mechanisms underlying these disorders.

The results of the study were made freely available to the community, representing a valuable resource for the many researchers who will undoubtedly apply this technology to further explore human cortical gene expression in the near future.

While it’s tempting to think that math is a discipline free from mistakes, the reality is quite different.  Published proofs have been found to contain errors and, worryingly, modern proofs are sometimes so long and complicated that it’s difficult for mathematicians to check that they are correct. (A proof, in mathematics, is a step-by-step logical argument that asserts some conclusion about a mathematical statement.) 

In a recent article published in the journal The Mathematics Intelligencer, Cambridge mathematician Anthony Bordg compared this situation to the replication crisis in science. According to his analogy, attempts to check the correctness of a proof are like attempts to replicate a scientific experiment.  If everything is correct, the proof has been replicated.  But if an error is found or if mathematicians cannot determine whether the proof is correct for some other reason, then the attempt to replicate the proof has failed. 

But too many proofs cannot be replicated.  So, what can we do to fix this?

One potential solution is to use computers during the peer review process.  Software called proof assistants can check if a proof is correct, once the proof has been translated into a language the software understands.  While human reviewers do not always rigorously check that every single inference in a proof is correct, a proof assistant does. And if it finds anything amiss, it will complain. A proof assistant's blessing therefore counts as a successful replication of the proof “once and for all.” 

But mathematicians have not yet welcomed proof assistants with open arms.  One problem is that they are not exactly user friendly, and Bordg acknowledges that there is plenty of room for improvement.  With further development, proof assistants will hopefully become more widely used in the near future.

Elon Musk, SpaceX's CEO and a notorious internet troll, announced in a tweet that one of SpaceX’s future missions will be paid for with Dogecoin, a cryptocurrency whose name is inspired by the Doge meme. This announcement fits with Musk’s track record of eccentric (and meme-like) moves, such as his launching a red Tesla into space for no good reason and his 2018 market-disrupting tweet that led to a lawsuit by the US Securities and Exchanges Commission. In similar pomp to how Reddit users caused Gamestop's shares to skyrocket in the recent wallstreetbets “GME to the Moon” campaign, Musk’s new tweet now also wants to take Dogecoin to the Moon, both literally and figuratively.

The mission referred to as DOGE-1 is, in fact, real — confirmed by collaborator Geometric Energy Corporation (GEC) in a press release. DOGE-1 will be a small satellite carried to the moon by a Falcon 9 rocket in early 2022, collecting yet unspecified images and other data of the lunar surface. Although Dogecoin started as a joke, this collaboration with GEC adds heft to Dogecoin’s tenuous reputation as a usable currency. GEC even claimed that Dogecoin “has been chosen as the unit of account for all lunar business between SpaceX and Geometric Energy Corporation and sets precedent for future missions to the Moon and Mars.”

As a leader in private space exploration, SpaceX is constantly setting precedents for humanity’s future in space, be it intentionally or not. It’s definitely worth considering what a future with meme missions dictated by the whims of a solitary billionaire would really look like, and if it's the kind of future we want.

In Darwin, Australia, a species of worm called Ramisyllis multicaudata makes its home inside the canals of a sponge. This worm is special — it can split and branch its posterior end. It is one of only two known species with this awesome adaptation. These worms might help us understand how different body parts grow and differentiate. 

A new study by researchers at the Universities of Göttingen and Madrid describe the worm's weird anatomy. Its head sits deep within a coral. Its various posterior ends  — in other words, its many butts — extend throughout the rest of the coral's canals. What always perplexed researchers was how the worm's body, especially its internal anatomy, could adapt to fit the coral. 

It turns out that every time that the worm's posterior splits into two (worms don't have butts, technically), its organs also split in half, and a "muscle bridge" forms to connect the split organs. The anatomy of these bridges suggested to the researchers that the worm's butt only begins splitting in adulthood. Its unique characteristics also allowed them to distinguish main branches from side branches.

They also figured out how this worm reproduces: from its butt, of course! The posterior ends begin to form reproductive organs, a nervous system, and eyes. The nervous system develops a brain-like ring around the intestines. It can then separate and search for a mate. While this study provides a lot more insight on this weird worm, it also shows that there's still a lot we don't know about its anatomy.

Did you know that you can help find new things in outer space?

You can, with Backyard Worlds. Backyard Worlds is a community (citizen) science project, a type of collaborative project where a large community helps scientists analyze data. Human eyes are often the best tool we have to look for changes or moving things in pictures of the night sky. If there’s a lot of data to sift through, scientists need more eyes to help look for interesting objects in their photos, and that's where you come in.

With Backyard Worlds, scientists and their community collaborators are searching for brown dwarfs, objects that are too big to be planets but not quite big enough to be stars. They found their first brown dwarf in 2017, and have just made another cool discovery — an unusual brown dwarf orbiting around a small red star. 

Two community scientists, Paul Beaulieu and Austin Rothermich, spotted the new brown dwarf in images from the Wide-field Infrared Survey Explorer (WISE) telescope. Their findings are described in a new publication in Research Notes of the AAS. 

Scientists captured observations of this brown dwarf with the Southern Astrophysical Research Telescope in Chile. It doesn’t quite match with any of the standard types of small stars or brown dwarfs, and seems to be right on the boundary between the two. 

Getting more data on this peculiar object will help scientists figure out exactly it is. In the meantime, you can join in the citizen science with Backyard Worlds to discover your own brown dwarf — or, if you’re more interested in galaxies, whales, or some other science, check out the other projects in need of assistance on Zooniverse. You might even get your name on a scientific paper, just like the discoverers of this new brown dwarf.

Our ability to “suppress” memories is quite useful. This prevents us from ruminating on painful moments, and can help us move forward. However, sleep deprivation reduces our ability to do so. In a recent paper in Trends in Cognitive Science, they put forward a model that links sleep deprivation with weakened control over our unwanted memories and emotions.

The researchers suggest that when we do not sleep, the right dorsolateral-prefrontal cortex (an area associated with self-control, memory, and attention) cannot properly block unwanted thoughts. This makes it difficult for us to suppress our negative memories, and can even make them pop up more frequently. This is corroborated by another recent study, in which sleep-deprived participants were also unable to “control” their memories. Not only were these participants unable to block them out, but they would often re-experience these thoughts frequently.

It appears that lack of sleep also makes us worse at controlling how our memories affect our emotions. In the same study, participants were shown images that could trigger negative feelings. Well-rested participants were not only able to suppress the memory of seeing negative images, but also reported less negative feelings when seeing these images compared to participants who were kept awake all night.

Taken together, this model suggests a link between sleep deprivation, memory and emotion control. Without sleep, many of the cognitive processes of the brain cannot function properly, potentially leading to a cycle of worsening psychological symptoms. For example, a person who has experienced a traumatic event could develop post-traumatic stress disorder (PTSD) and insomnia, worsening their recurring thoughts, which could lead to reduced sleep quality and more unwanted feelings. The researchers even suggest that this model might apply to other disorders that are characterized by unwanted, recurring thoughts, such as depression, obsessive-compulsive disorder, and schizophrenia.

Earth's atmosphere owes its oxygen to life. With an energy boost from sunlight, photosynthesis combines CO₂ and water, yielding sugar and oxygen. But turn off the lights, and making oxygen gets tricky. Only a small handful of microbes are known to do it. But dark oxygen production might be far more common — and important — than previously thought. 

Ammonia-oxidizing archaea (AOA) are widespread microbes found everywhere from the seafloor to Mt. Everest. They convert ammonia into nitrite for energy in an oxygen-dependent process called nitrification. Despite this, AOA somehow thrive in oxygen-minimum zones (OMZs), regions in the ocean where oxygen concentrations plummet.

Researchers at the University of Southern Denmark recently announced in a pre-print (a completed study which has not yet passed peer-review) that an AOA called Nitrosopumilus maritimus may have let them in on the secret to its success in OMZs. Sealed up in airtight containers, N. maritimus grew in the lab under the watch of super-sensitive oxygen sensors. As expected, the cells quickly consumed all available oxygen, using it for nitrification. But then something strange happened. Right after oxygen concentrations hit zero, they rose again. After two years of experiments it was clear that instead of dying out or hibernating after running out of oxygen, N. maritimus made its own oxygen from nitrite, producing dinitrogen (N₂) as a by-product. 

Additional tests confirmed that N. maritimus wasn't using any of the three previously known ways of making oxygen in the dark — its trick was all its own, and not only a novel method of light-independent oxygen production but also a completely new chemical pathway for recycling biological nitrogen into N₂.

This new metabolism can't replace photosynthesis—oxygen in the N. maritimus cultures peaked at levels about 1000x lower than would have been expected from photosynthesis. But because AOA are both incredibly common and critical for the nitrogen cycle, dark oxygen production might be far more important and widespread than previously thought.

Throughout the United States, many people are living and working in close proximity to Superfund sites — areas contaminated with leaked, dumped, or poorly managed hazardous waste. Superfund sites are often laden with heavy metals, asbestos, pesticides, and radioactive compounds, and the cleanup process for these contaminants can take many years.

Recently, a team researchers from the University of Houston and the University of Texas investigated how living near a Superfund site relates to life expectancy. In their study, which was published in Nature Communications, the researchers compared the life expectancies of people living in census tracts with a Superfund site to those living in neighboring tracts. (US census tracts contain approximately 4,000 people.) In addition to the more than 1,300 listed Superfund sites in the US, this study also included an additional 11,700 contaminated sites that are not currently on the Environmental Protection Agency’s National Priorities List.

They found that people living close to hazardous waste sites tend to have shorter life expectancies than those living further away. And life expectancies decreased even more for people near contaminated sites that were not being actively cleaned up, as well as for those living in flood-prone areas.

But these effects were not distributed equally for all people. The study found a clear negative relationship between contaminated sites and life expectancy in low-income census tracts, but not in higher-income areas. Wealthier residents may be able to avoid the risks of living near hazardous waste by paying for expensive health care and well-protected houses. Similarly, areas where most residents had health insurance showed little relationship between contamination and life expectancy.

While living near hazardous waste is likely to be dangerous for anyone, these risks seem to be magnified for the most socioeconomically disadvantaged residents. And to make matters worse, hazardous waste sites have disproportionately been built in low-income and racially marginalized communities. Hopefully the ongoing and future cleanup of these sites will lessen these disparities.

What do we have in common with blackbirds, frogs, and rabbits? We all have guts that are brimming with bacteria. However, while we know a great deal about human gut bacteria, the relationship between intestinal microbes and the health and lifestyle of wild animals is relatively unclear. Indeed, these tiny gut-dwellers could be the secret behind why some animals eat foods like rotting meat or poisonous plants without getting sick, or are immune to various diseases. 

In a new study published in Science, scientists sought to learn more about the gut microbes in animals from diverse classes, such as mammals or birds, and exhibiting different feeding behaviors, geographical location, and traits like body mass and lifespan. 

The investigators collected poop from 180 species of animals across the world, including everything from penguins and gorillas to kangaroos and turkey vultures. After sequencing DNA in the poop, the investigators used computer programming to characterize the bacterial community within the samples. 

They found that the animals’ gut bacterial communities varied depending on their class and traits like diet, body mass, and social structure (i.e. solitary vs social). Excitingly, over 900 of the 1209 bacterial species identified had never been recognized before. These mysterious microbes likely confer health benefits to their host. For instance, the investigators discovered novel microbe-associated enzymes in the gut of griffon vultures, which eat dead or decaying animals, that can degrade bacterial toxins. These enzymes may protect the birds from getting sick when they chow down on pathogen-infested meat. Similarly, some animals had microbial genes in their guts presumably associated with antibiotic biosynthesis or degradation of human-made chemicals. 

These results shine light on the associations between gut bacteria and animal physiology and behavior. Moreover, they suggest that animal guts may be gold mines for discovering bacteria with potential clinical and industrial applications, including those that produce novel antibiotics or compounds capable of eliminating industrial waste. 

New archaeological discoveries and improvements in our technology make it even easier to peek into the lives of Tyrannosaurus rex, the apex predator that roamed the earth more than 60 million years ago. Based on the size of their skulls, many paleontologists didn't think the T. rex was capable of complex behavior. Many were doubtful that T. rex lived or hunted in groups. But a new study of fossils preserved in a Utah quarry suggests that T. rex was indeed social. Researchers assessed a T. rex mass death site, the first of its kind.

In July 2014, the researchers explored the Rainbows and Unicorns Quarry in Utah. To their surprise, they found many fossilized T. rex specimens across a hectare of land. An analysis of the ancient landscape and erosion patterns revealed that the bones had been disturbed by river flooding, and so the researchers were challenged to prove the fossils weren't just brought together by the river.

The researchers looked at the chemical composition of these samples. If the dinosaurs died together, they predicted that they would find similar amounts of chemical elements in the fossils. After conducting their analysis, they verified that the fossils were created in the same environment, at the same time. Likely, this group of T. rex fell victim to flooding on the river.

With many other fossils buried in the quarry, this may be the first of many fascinating discoveries to come.

Visions of humans on Mars are now one step closer to reality. The Perseverance rover, which has already recorded the first sounds from another planet and flown the first helicopter on Mars, recently made another historic first—extracting oxygen from the Martian atmosphere.

Last month, the rover fired up one of its experiments known as MOXIE, the Mars Oxygen In-Situ Resource Utilization Experiment. Like the Ingenuity helicopter, this experiment is a technology demonstration, where scientists try something entirely new and never before attempted as part of a larger space mission. 

Inside the small metal box that is MOXIE, Martian air was heated to almost 1,500 degrees Fahrenheit, splitting carbon dioxide (CO₂) into one carbon monoxide (CO) and one oxygen atom (O). Mars’s atmosphere is around 96 percent carbon dioxide, so there’s plenty to use there! In its first hour-long test, MOXIE produced 5 grams of oxygen, enough for an astronaut to breathe for 10 minutes. Scientists will run a few more tests with MOXIE during the rest of the rover’s mission, trying to see how much oxygen it can make and how fast.

MOXIE addresses two huge challenges in human space exploration on Mars — finding enough breathable air for astronauts to stay alive, and bringing enough fuel for the rockets to make a return trip to Earth. Oxygen is a key part of rocket fuel, and getting four astronauts off the Martian surface and back to Earth would take a whopping 55,000 pounds of oxygen! Missions to Mars can’t just carry that much oxygen to Mars for the whole trip — it would make the payloads too heavy. MOXIE only weighs about 17 pounds, so future technology like this could help cut down the weight we have to haul with us on trips to Mars. 

Even if Mars won’t ever be a home quite like Earth, this experiment made a huge leap forward for our prospects of visiting the Red Planet.

Like fashion, popular medical topics come in phases. One favored subject now is the gut-brain axis: investigating how our stomachs and guts influence the rest of our bodies, both physically and mentally. 

The first notable focus on “the great abdominal brain” in Western medicine was actually in the nineteenth century, which left us with an abundance of physicians’ writings on the topic. While physicians were particularly interested in the nerves surrounding the guts (these nerves were already known to affect behavior), studying the body holistically lost its popularity in the twentieth century and the focus shifted to studying individual organs and cell types. 

These changes in holistic versus reductionist medical trends reflected the waxing and waning in general curiosity of the gut-brain axis. We are now seeing a renewed trend toward holistic biomedical approaches, with increasing research on the connections between our guts and brains. 

This focus, paired with the recent eruption of neuroscience techniques, has made unique gut-brain axis experiments possible. For example, a study published in the journal Cell Metabolism characterized nerves that relay information from the gut to the brain. They found that in mice, different nutrients recruit distinct nerves, which makes sense given that nutrients are detected by specific receptors. This means that information about nutrients being transmitted from the mice guts to their brains remains segregated.

One type of cell closely linked with food intake in the brain is AgRP neurons (neurons that make a protein called "Agouti-related protein"). An animal eats when these neurons are more active. Conversely, if AgRP neuron activity is suppressed, even starved animals cease caring about food. 

Researchers monitored these AgRP neurons in the brains of mice, while they ingested different foods. Assessing AgRP responses allowed the researchers to infer whether information about how each specific nutrient they were interested in was processed in the brain. Nutrients are primarily detected in the small intestine, and this study reports that certain nutrients are sensed in different parts of the small intestine. By identifying the distinct nerves relaying these signals, the researchers have confirmed that there is a labyrinth of pathways that convey caloric intake from our guts to our brains for maintaining energy balance.