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Calculating the entropy of black holes helps solve fundamental questions about our universe

Physicists have shown that the Cardy limit can be used to calculate entropy

Marina David

Theoretical Physics

University of Michigan

Black holes are mysterious objects in space that physicists use as a tool to learn about gravity. On the experimental side, physicists use data from large telescopes to further understand how our universe works. On the theoretical side, the mathematics behind how black holes work have become our main guide towards a more fundamental interpretation of our universe.

Currently, physicists, including myself, are trying to explain the properties of black holes. This turns out to be quite a challenge! One way to tackle this is to use a principle that relates the gravitational theory of black holes to another physical theory called quantum field theory. This principle has become a dictionary of sorts, allowing us to translate ideas about black holes, such as entropy and temperature, between gravitational theory and quantum field theory. 

Recently, a group of scientists has predicted the entropy of black holes on the quantum side using a unique method, called the Cardy limit. The Cardy limit is a limit on the angular momentum of the black hole and corresponds to highly spinning black holes. No one has yet confirmed this method on the gravity side.

My collaborators and I have taken on this challenge to verify that the Cardy limit is valid on the gravity side and reproduces the expected entropy. It turns out this method works best when we zoom towards the event horizon of a black hole — a region of spacetime that acts a bit strange. If we get too close to the event horizon, nothing — not even light — can escape and we are destined to fall into the black hole! Yet, this region of spacetime along with the Cardy limit lead us to the same entropy and other properties of the black hole that were computed on the quantum side.

Our paper is one of many recent results that aim to solve the riddles behind black holes. It is a step towards getting closer to a full understanding our of universe.

Sabre-toothed carnivores killed many types of prey in many ways

New study reveals richer diversity among these convergently evolved predators than previously thought

Hector Tejero

Ecology & Evolutionary Biology

Institute of Evolutionary Biology, Barcelona

In evolution, convergence refers to different groups of organisms developing a similar body structure independently. Birds and bats are a common example: They both have wings, but those wings evolved independently. This concept is very useful for comparative biology, since convergence in the shape is usually related to convergence in the function — different organisms with similar structures usually show similar behavior involving that body structure. Thanks to the phenomenon of convergence, we learn a lot about how extinct species lived by looking at their body structures in the fossil record.

However, this can sometimes be misleading. 

In a paper recently published in the journal Proceedings of the Royal Society B, researchers explore convergence in the skulls of sabre-toothed carnivores. Sabre-tooth skulls, often showing remarkably elongated canine teeth, evolved independently in unrelated groups of animals over more than 200 millions of years. Until now, scientists interpreted that skull shape as an adaptation for eating large animals, assuming each of these carnivores had a similar hunting behavior. 

The researchers, however, found evidence against this assumption. They performed a series of biomechanical analyses, studying jaw shape and bite force. These analyses led them to conclude that animals with sabre-tooth skulls prey on animals of a variety of sizes — not just large prey. They also use their skulls to kill in many ways, including a ‘killing bite’ and a ‘canine-shear bite’. 

This study shows a disconnect between morphological convergence and functional convergence. Most importantly, it is an example of one essential characteristic of science: the ability of revising long-standing assumptions and assessing their prevalence when new methodologies and ideas are developed.

Killing germs with slime bacteria M. llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogochensis

The very real soil microbe uses chemistry to hunt other microbes

Dori Grijseels

Neuroscience

University of Sussex

When scientists discover a new species, they are allowed to make up its binomial (Latin) name. This results in interesting names, like Scaptia beyonceae, a horse fly that was named after Beyonce, or Laboulbenia quarantenae, which got its name because it was discovered during quarantine. Scientists from Aberystwyth University in Wales, UK, decided to keep it simple and name one of the species of myxobacteria after where they found it. The only problem: it was found in Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch, giving this species the name Myxococcus llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogochensis.

Myxobacteria are slime bacteria that mostly live in the soil and have particularly large genomes. By studying those genomes found in soil samples, David Whitworth and his team identified five new species. These species are interesting because they create many different chemicals, including some that hunt other microorganisms, which are potential antibiotics. 

In their study published in Genome Biology and Evolution, the scientists searched the genome of the myxobacteria for gene clusters producing and found that more than two-thirds of them were new gene clusters that had not been found before. This makes these species great candidates for finding new bioactive components that can be used to create new drugs and other useful substances.

The scientists named another one of the species they found after its location: Pyxidicoccus caerfyrddinensis, which was found in Caerfyrddin. The other three species got the names M. vastator (meaning ‘ravager’), M. eversor (meaning ‘destroyer’), and P. trucidator (meaning ‘slaughterer’), named for their hunting abilities. All pretty badass names, if you ask me!

Stress hormones and mitochondrial health determine who will lose muscle after surgery

New research uncovers the cellular and genetic risk factors of post-surgery muscle loss

Luke Whitcomb

Physiology and Biomedical Sciences

Colorado State University

It’s common for people to lose muscle after surgery. Such degradation can result in longer recovery periods and increased risk of injury or death. But people often experience different degrees of muscle loss — even after undergoing the exact same procedure.

Understanding this variation may help to identify high-risk patients, develop therapies to prevent muscle degradation, and expedite recovery.

New research from the National Heart and Lung Institute at the Imperial College in London suggests two factors may be key: levels of the stress hormone cortisol, which causes muscle breakdown; and the health of your mitochondria prior to surgery. 

To evaluate these factors, the researchers used ultrasound imaging to scan the rectus femoris — a larger muscle in the thigh — of 20 male patients before and after aortic valve surgery. In addition, blood samples were collected to search for both compounds excreted by dysfunctional mitochondria and stress hormones such as cortisone and cortisol.

When the body is under stress, cortisone converts to cortisol, which signals for muscles to be broken down for emergency fuel. This cortisol is then converted back to inactive cortisone through the enzyme 11‐βHSD2. Researchers found that the ratio of cortisol relative to the amount of cortisone was higher in patients who experienced more muscle loss. This indicates that 11‐βHSD2 may be less active in these patients.

Mitochondria are small subunits of animal and plant cells in charge of producing energy and maintaining electron balance. When these subunits are damaged, as in diseases such as diabetes, cancer, or other diseases, they take up less fuel from the blood and produce more compounds associated with inflammation. In surgery patients who lost more muscle, researchers detected less mitochondrial fuel uptake and more inflammatory markers.

This research indicates that genetic factors that influence cortisol inactivation and mitochondrial damage due to pre-existing conditions like diabetes may make a person more likely to lose muscle after surgery. 

Worms and germs in ancient poop tell us about past human health

DNA from centuries-old toilet scrapings can help us today

Farah Qaiser

Molecular Genetics

University of Toronto

To better understand human health in earlier centuries, scientists can turn to many different methods, including pottery analysis, radiocarbon dating or simply perusing old records. But answers can also be found in unlikely places — such as ancient latrine sediment, which is the collective biological waste generated by past communities.

(Yes, I am talking about ancient, fossilized human poop.)

In a new study published by The Royal Society, researchers investigated the parasites and human gut microbes found in ancient human feces and latrine sediment at two archaeological sites found in Jerusalem and Riga, Latvia. 

During the 15th century, the Jerusalem latrine was used by multiple different users from more than one household. Eggs in that fossilized feces belonged to various helminths, such as the roundworm and tapeworm. Similarly, the Riga latrine was dated to 1536 CE, and was reported to be used by the general town population. Researchers extracted DNA from sediment samples in the two latrine sites and sequenced that DNA to build a picture of the organisms present in ancient human gut microbiomes.

The researchers identified a range of bacteria, archaea, parasitic worms, and other organisms present in the ancient human gut, though it should be noted that findings are representative of the community as a whole, rather than a single person. One example is the Bifidobacterium species, which are generally enriched in populations with industrialized agriculture.

Overall, this study showed that DNA is still preserved in ancient latrines, and that ancient poop from toilets that have long been out of order can still reveal information about past human health.

Microscopic physical forces shape developing embryos

Research in African clawed frogs shows the importance of mechanical cues in early development

Raj Rajeshwar Malinda

Cell Biology and Developmental Biology

In animals, early developmental events are complex processes crucial for an individual to live a healthy life. Biological factors such as genetics and protein production are known cues that are important for embryonic development, but still not enough to trigger every step. 

Recently researchers at the National Institute for Basic Biology in Japan published a study demonstrating how mechanical cues — physical forces acting on dividing cells and developing tissues — influence early developmental processes in animals. Using the African clawed frog (Xenopus laevis) as a model organism, they showed that as the shapes of tissues change from forces like stretching and pulling, chemical signals cascade through the frog's embryo and help it develop. This healthy development makes the tissues more resilient and prevents them from becoming deformed during later stages of development, highlighting the primary importance of mechanical cues in embryonic development.

Viruses can 'spill back' into wildlife populations, increasing the risk of disease in humans

Using yellow fever as a case study, researchers examined whether chikungunya, Zika, and dengue could become established in the Neotropics

Alejandro Rossi

Biology

Universidad Nacional de Córdoba

As the COVID-19 pandemic has made very clear, viral spillover from animal hosts to humans is a serious threat. However, viruses are also capable of spilling back into wildlife from humans, establishing reservoir populations in wildlife in new geographic regions. This idea of "spillback" is also an important aspect for scientists to study in our efforts to prevent pandemics.

A paper recently published in PLOS Neglected Tropical Diseases looked at viral spillback in the Neotropics—Central and South America, as well as Mexico and the Caribbean. They used yellow fever as a case study, as it has spilled back and established a persistent enzootic reservoir in primates and mosquitoes. They wanted to understand what ecological factors may cause other viruses to do the same. They highlight the endemic circulation of the chikungunya, dengue, and Zika viruses as other points of concern for South American countries. All of these are spread by mosquitos and have primate hosts.

The researchers used mathematical modelling to explore how a spillback event could play out. Parameters such as the virus' extrinsic incubation period, mosquito lifespan, and primate population size, predicted the effects a single infected primate might have in creating an enzootic reservoir. Evidence showed that given the right conditions, spillback events can occur and the chikungunya, dengue, and Zika viruses could establish persistent reservoirs in the Neotropics. This possibility is of great concern to epidemiologists, given the danger of these four mosquito-borne viruses to humans.

A captive breeding program taught Puerto Rican parrots to "speak" differently

The new dialect may now complicate their conservation

Enzo M. R. Reyes

Conservation Biology

Massey University

Parrots are one of the most diverse groups of birds and can be found across the tropics. Aside from their colorful beauty, parrots are also popular due to their intelligence and ability to mimic different sounds, including human language. 

But it is this popularity with humans that threaten wild parrot species. This is the case with the Puerto Rican parrot, a critically endangered species whose fate depends mainly on the efforts of captive breeding programs and reintroductions.

The Puerto Rican parrot has been a focus for conservationists since the 1970s when a captive breeding program began. Since then, several captive parrots have been reintroduced to the wild. During the early stages of the program, due to the small number of adult Puerto Rican parrots, conservationists used Hispaniolan parrots to help raise the chicks. 

Now decades later, scientists have shown that this likely led to a new dialect of parrot calls in the captive breeding population. This turned out to be a pesky problem. Since the captive birds communicate differently than the wild ones, the process of reintroduction might be harder. 

Although geographic differences in vocalizations and dialects across populations are common in the wild, this is the first time that researchers found the development of a new dialect linked to conservation practices. Now, conservationists are exposing the captive-bred population to the vocalizations of wild birds with the goal of familiarizing the captively-bred parrots with the dialects of wild populations. 

Rodent fathers suggest dopamine is key to an neuroscience of parenting

A new study shines light (literally) on the brain chemistry of paternal behavior

Laura Haetzel

Neuroscience

UC Berkeley

Good parenting is essential to the survival of species across the animal kingdom. However, parenting is often linked exclusively to maternal care. Years of insightful scientific work have explored the maternal brain, identifying exactly what molecules give rise to maternal behavior. The research landscape investigating the neuroscience behind paternal care is comparatively barren.

Psychology studies show that both maternal and paternal care crucially shape a child’s development. Why, then, do most studies only look at the neural mechanisms of maternal care? The scientific techniques used address such questions are highly invasive and cannot be used in humans. Neuroscientists thus conventionally turn to non-human mammals. However, very few non-human mammals demonstrate paternal behavior.

A paper recently published in the journal Cell circumvents this issue. The researchers studied both mouse and rat sires — male rodents that have fathered offspring. Mouse sires naturally demonstrate paternal behavior, whereas rat sires do not. To find the difference between the paternal mouse brain and the non-paternal rat brain, they looked at a brain region called the hypothalamus because it has been identified as a key region in maternal parenting behavior.

The hypothalamus receives many inputs, including from neuroendocrine dopamine neurons. As their name suggests, these neurons release dopamine. The researchers measured the amount of dopamine released onto the hypothalamus in mouse and rat sires and found a key difference: the levels of dopamine were higher in rat sires than in mouse sires. 

The researchers then tested the hypothesis that higher dopamine levels released onto the hypothalamus lead to reduced paternal behavior. Using optogenetics — a technique that uses light to activate neurons — they manipulated the dopaminergic neurons of the paternal mouse sires to release more dopamine. As predicted, the mouse sires showed impaired paternal behavior.

This addresses an important gap in the scientific literature on parenting. We now know that the rodent brain has built-in mechanisms to regulate paternal behavior. It would be interesting to explore the same effect in human fathers, when scientific techniques advance to be less invasive.

Iberian lynx eat more species of prey than previously thought

This big cat has recovered from the brink of extinction over the past 20 years

Luis Manuel Fernandez Porras

Conservation Biology

Canadian Organization for Tropical Education and Rainforest Conservation

Iberian lynx (Lynx pardinus) has been a paradigm of conservation efforts in Spain for decades. Between 2000 and 2019, its population increased from about 250 to 400 lynx, due to conservation initiatives such as translocation and reintroduction. Most of the studies on this species happened in southern Spain, where the Iberian lynx was considered a trophic super specialist, but there are populations in central Spain as well. Its decline has been attributed to the decline of its main prey species, the European rabbit. Now, research has challenged the traditional vision of the Iberian lynx as a trophic specialist. The lynx has a much wider diet than previously thought.

Within mammals, the study of large predator diets is mostly based on analyzing their scat (fecal matter) for undigested content such as hairs or feathers that hints at what the predator is eating. To do so, the first step is to find the scat and properly identify what species they belong to. In the case of Iberian Lynx, its scat is easily misidentified as belonging to European wildcats and red foxes. Therefore, in this study, genetic methods were necessary to properly identify the scat samples.

Researchers classified the content found in 46 scat samples into four different groups (small mammals, lagomorphs, birds, and ungulates) and calculated the proportion of each of them in the total. They compared these proportions between the central and southern lynx populations, and found that the former is better able to adapt to sub-par ecological conditions. They adopt a more generalist diet when there is an abundant variety of prey and a more specialist diet when there is low prey diversity.

Understanding the variables that determine the presence of a species in a specific habitat is vital to take informed decisions on wildlife management and to implement successful conservation actions. This finding sheds new light into the biology of an endangered and charismatic species of the Iberian fauna that can improve its recovery from the brink of extinction.

Marine sponges are coral reefs' great recyclers

Sponges eat the "marine snow" that falls from other organisms in the ocean

Sarah Heidmann

Fish ecology

University of the Virgin Islands

There are many threats to tropical coral reefs. For example, in addition to climate change, corals are susceptible to being smothered by sedimentation, and fishes are being extracted faster than they can reproduce. But these are not the only types of life on a reef.

Marine sponges, which are typically overlooked by recreational divers attracted to the colorful and active fish and to the corals that form massive bioengineered structures, play a key role in coral reef ecosystems through nutrient cycling. A paper recently published in the ISME Journal has determined the mechanism by which marine sponges consume and digest dissolved organic matter, or DOM. 

Just as dust in your home comes in part from dead skin, DOM  (sometimes called “marine snow”) is bits of carbon sloughed off of various ocean-dwelling organisms. Sponges filter these particles out of the water, using it as one of their main food sources while cleaning the water for more sensitive organisms like coral.

The predominant opinion used to be that DOM processing is performed by bacteria acting as symbionts, but this study found it also occurs in the cells of the sponge itself, with ratio of sponge versus symbiont processing varying across species and environments. This strategy of recycling has allowed sponges to exist for over 600 million years without large changes in their approach to life. 

Your antidepressants could affect color-changing shrimp

The jury is still out for the shrimp, but our medications do affect water-dwelling wildlife

Rafe Cotton

Marine Biology

The common sand shrimp, Crangon crangon, a small shrimp endemic to the northeast Atlantic, is capable of changing color to match its surroundings. This superpower is made possible by pigments in special organs embedded in their skin called chromatophores.

The effects that antidepressants have on wildlife is a growing research topic as more people take these drugs and secrete the leftover compounds into wastewater. These compounds then find their way into water bodies, like the ocean. They are so damaging due to their effect on the neurotransmitters, molecules important for movement, present in all animals.

A pair of researchers from the UK's University of Portsmouth designed an experiment to investigate the possible interaction between antidepressants and cryptic coloration in sand shrimp. They exposed adult shrimp to varying low levels of the antidepressant fluoxetine for three time intervals (1 hour, 1 day, or 1 week). Then, they altered the color of the substrate the shrimp were in from solid white to solid black and measured how dark their bodies became as the shrimps' chrompatophores gained or lost pigment. 

The results of the investigation were inconclusive. In two of the three studies the researchers saw a high degree of correlation between shrimp "darkness" and substrate color. But, there was no clear effect of fluoxetine exposure on this correlation. Although inconclusive, this investigation does draw attention to an important issue: how do the medications we take affect wildlife downstream?

Testing for lesser known antibodies produces a better COVID-19 test

Most antibody tests look for responses to SARS-CoV-2's spike protein, but more accurate results include antibodies against the virus's other proteins

Kialani Mackey

Biology

Occidental College

Before we can go back to a somewhat “normal” state, many scientists say we need widespread testing and contact tracing—but how effective is our current testing system? 

To determine if someone currently has COVID-19 we test for the presence of the virus. To determine if someone was previously infected, we test for the antibodies their body produced in response to the infection. These antibodies usually specifically target the COVID-19 spike protein—an appendage that helps the virus enter human cells. 

Many caution against the accuracy of COVID-19 tests as studies show a growing number of false negative results from infected individuals with milder symptoms. A paper published recently in Nature outlines that analyzing antibody responses to the lesser studied, nonstructural COVID-19 proteins—proteins of unknown function—answer this diagnostic problem.

These researchers measured levels of antibodies targeting various COVID-19 proteins in the blood of infected and uninfected individuals. Results showed that analyzing the combined antibody response to the presence of two specific nonstructural proteins, called ORF8 and ORF3b, produced results that were 73 percent more accurate than testing for all spike protein antibodies. 

ORF8 and ORF3b antibody levels were most constant across infected participants from 1 to over 30 days after the onset of symptoms. This suggests that, unlike the current spike protein antibody test, diagnostic tests looking at ORF8 and ORF3b antibodies are ideal for diagnosing individuals with current or past COVID-19 infections.  

COVID-19 testing previously ignored nonstructural SARS-CoV-2 protein antibodies. But now these have clear potential to replace current diagnostic targets. More accurate testing will allow for both the public and public health experts to better understand the spread of the virus so that they can work together to contain this destructive pandemic. 

Flash droughts are a new type of extreme weather event

Scientists are figuring out how to pinpoint the onset of a flash drought

Jack Hawley

Oceanography

Humboldt State University

You’ve heard of a flash flood, but what about a flash drought? Flash droughts are extreme weather events that occur rapidly, much like flash floods, and can have severe impacts on plants, animals, and people. Researchers at the National Center for Atmospheric Research in Boulder, Colorado in collaboration with Californian, Australian, and German universities have now proposed two methods to identify whether an area is suffering from a flash drought.

Currently, most drought monitoring is done on a monthly or weekly schedule. But flash droughts need monitoring methods for daily timescales. One potential variable that these researchers draw on is the Evaporative Demand Drought Index (EDDI), a measurement of how "thirsty" the atmosphere is in a certain location for a given period of time. They also propose using the US Drought Monitor (USDM). This system classifies areas by five categories that range from D0 (abnormally dry) through D4 (exceptional drought).

Using these metrics, the researchers came up with two scientific definitions for flash droughts: 

1) A 50% increase in Evaporative Demand Drought Index (EDDI) for two weeks, with the resulting high EEDI levels persisting for another two weeks

2) A two-category change in the USDM over two weeks that persists for another two weeks.

Both definitions come with their own caveats, but the researchers note that the first definition could be a good general definition for prediction and climate change research. Because the second definition uses the USDM, it is only relevant in the United States, and this definition would have to be tailored to existing drought monitoring systems for use in other countries.

These definitions are a good foundation for the next steps toward understanding flash droughts: Future research on the connectivity of soil moisture, land to atmosphere interactions, large scale atmospheric events, and the effects of a changing climate will be needed to characterize this new type of extreme weather event.

Eating a high-fat diet could change your brain for the worse

Research in mice shows how fatty foods alter the brain's response to healthy foods

Samuel J Walker

Neuroscience

Harvard Medical School and Beth Israel Deaconess Medical Center

Dieting is notoriously difficult. Thanks in part to evolution, we love foods that are high in calories. Not only that, but once we have experienced the kind of high-calorie foods that surround us in the modern world, more nutritionally-balanced foods become much less attractive. But why?

To understand how the brain makes dieting so difficult, and high-calorie foods so tempting, the authors of a recent study turned to mice, where they could record and manipulate the activity of specific neurons involved in energy balance and reward. They asked how exposing mice to high-calorie foods affected their consumption of, and neural responses to, regular foods.

When researchers gave the mice access to both high-fat (HFD) and standard (SD) diets, mice completely stopped eating the SD almost immediately, and preferred the HFD. They then removed the HFD, and saw that mice still ate very little SD, and so lost substantial weight. This devaluation of regular food was so strong that even fasting mice presented with an SD ate very little — they would only eat a lot if the HFD was available. Just experiencing the HFD for 24 hours was enough time to make the SD less tasty.

a cartoon of a mouse eating human foods

Suzanne Beaky 

To see how HFD exposure affects the brain’s response to food, the scientists recorded the activity of AgRP neurons, a population of neurons that is active during hunger and controls energy balance, and midbrain dopamine neurons, which release dopamine as a signal of reward. Exposure to the HFD greatly reduced the response of both groups of neurons to the SD: afterward, these neurons would only respond strongly to the HFD. Regular food became less rewarding, and less satiating, than high-calorie food.

Under normal conditions, AgRP neurons would only respond to food when a mouse is hungry. But after HFD withdrawal (mimicking dieting), the AgRP neurons became so sensitive to HFD that they would respond even if the mouse was not hungry. This could explain why when we diet, high-calorie foods are so hard to resist – these foods become rewarding even when we aren’t hungry.

This study suggests that exposure to a HFD alters the brain’s response to food so that only high-calorie foods are rewarding and satiating, while more nutritionally-balanced foods become less valuable. And, abstaining from high-fat foods might just make our brains' hunger centers responsive to these foods even when we’re not hungry, making it difficult to resist the urge to binge. Research on the circuits that regulate food intake will potentially lead to therapies that allow us to manipulate these biological urges and control the obesity epidemic.

Scientists identify a powerful anti-inflammatory compound in psychedelic drugs

The compound, called 2 C-H, reduces inflammation without mind-altering effects

Milena Marinković

Neurobiology

University of Exeter

People have long believed that using psychedelic drugs such as LSD, DMT, and psilocybin (from ''magic mushrooms") can help the body fight inflammation. Scientific support for this idea has emerged in the past couple decades, and newly published research goes further to show exactly which structural parts of these molecules are responsible for the anti-inflammatory effect.

Psychedelic drugs exert their profound effects on the mind by interacting with a serotonin receptor in the brain called 5HT-2A. This receptor can also be found in almost all other parts of the body, including immune-related structures like the spleen and white blood cells. The effects of serotonin made in immune cells are mainly pro-inflammatory, and its secretion can influence the progression of disorders like asthma and rheumatoid arthritis.

Like serotonin, psychedelic drugs can also activate the 5HT-2A receptor and reduce inflammation. This new study, which was published in ACS Pharmacology & Translational Science, shows what molecular structure is responsible for this effect. The researchers looked at rats with asthmatic symptoms to test 21 different compounds that activate the 5HT-2A receptor, and found that many of them were able to prevent and reverse inflammation in the lungs. They also discovered that the compound called 2C-H has the molecular structure that yields the fullest anti-inflammatory effects of the compounds they tested.

2C-H is structurally very similar to the popular psychedelic drug 2C-B (which is similar to ecstasy and MDMA), but it does not itself have any psychoactive effects. As such, 2C-H might open an exciting new venue in anti-inflammatory drug design: it is a powerful anti-inflammatory agent that won't get you high.

Keystone predators could help mitigate the effects of climate change

Sea otters keep Aleutian kelp forests healthy

Ashley Marranzino

Marine Biology

University of Rhode Island

Keystone species maintain order and uphold the balance in ecosystems. Scientists studying the shifting landscapes of Aleutian kelp forests suggest that keystone species may also help ecosystems cope with climate change. 

Sea otters are renowned keystone species — by preying upon kelp-eating sea urchins, sea otters regulate urchin populations and protect the entire kelp forest ecosystem. When fur traders depleted sea otter populations in the 18th and 19th centuries, sea urchins populations grew unchecked and decimated kelp forests. Kelp forests rebounded when sea otters were reintroduced, but sea otter populations are once again declining as the growing killer whale population — recovering from pre-industrial whaling — has added sea otters to their menu. In the absence of sea otters, sea urchin populations can once again flourish, jeopardizing kelp forest health. 

The slow-growing, calcareous red algal species (Clathromorphum nereostratum) that builds the Aleutian kelp forests managed to survive destruction when sea otters were initially wiped out because its hard skeleton deterred sea urchin predators. But climate change has made the algae susceptible to over-grazing as warming water speeds up sea urchin metabolism and ocean acidification weakens the algae’s protective skeleton. 

Aleutian kelp forests are rapidly declining due to combined effects from the restructuring of food webs and environmental changes. Based on models of sea otter abundance and sea urchin grazing rates on the red algae over the past 40 years, scientists suspect that kelp forest loss was initiated by the disappearance of sea otters and then worsened by environmental changes. If sea otters recovered, however, the researchers believe they would serve as a buffer — mitigating the detrimental effects of climate change on the kelp forest environment. It is possible that other keystone species could help lessen ecosystem changes in the face of rapidly changing environmental conditions. 

Daisy Shearer

Experimental Quantum Physics

University of Surrey

You may know that there are two classes of fundamental particles — fermions and bosons — underlying what we normally think of as matter. Neutrons, protons, and electrons are all fermions; photons are an example of bosons. Fermions repel each other, and bosons don't. These quantum statistics are well-known. But physicists have now observed particles that don’t fall under either category. 

Enter the anyon: a type of quasiparticle found in two dimensional systems which is neither a fermion or a boson that may be the key to the next stage of quantum technologies.

Although anyons have been theorized for many years now, evidence of such particles has only recently been observed experimentally. Anyons are of particular interest in the field of quantum computing as they are the building blocks of the topological quantum computer, which physicists believe would make a more stable version of the technology. But to bring such a machine out of the realm of theory and into reality, we first need to be able to create and control anyons.

In their experiment published in April in the journal Science, physicists developed a tiny particle collider to detect anyons. The device was made of a microscopic semiconductor. Inside this material system, electrons were confined in two dimensions. And in the presence of a large magnetic field, anyons arose. But here’s where things got a little tricky: because of the quantum mechanical nature of such a system, researchers needed to use sophisticated techniques, such as quantum tunneling, to guide, collide and detect the anyons.

They were able to study the quantum statistics of the system and see evidence of anyons in their experiment. They saw that the particles in their device did not display fermion-like or boson-like statistics, but instead something in between. Their results provide experimental evidence for the anyon-statistics previously predicted theoretically. 

This is the first step in a long journey to creating a physical topological quantum computer. Although likely to take decades, such a technology could revolutionize our society. But first, we need to learn a lot more about anyons to uncover their potential in quantum technology and beyond. 

Noisy, high-speed recreation disturbs sensitive wildlife

Camera traps in British Columbia show that mountain biking and ATVs affect wildlife more than hiking or horseback riding

I remember the first time I flipped through the images from a camera capturing the lives of wildlife without any humans around. After countless videos of grass blowing in the wind, there it was: A leopard, stalking a diminutive antelope called a dik dik through my experimental plots in the Kenyan savanna. I’ve been hooked ever since.

These glimpses into the animal world can help us navigate the needs of both wildlife and human recreation when designing protected areas. With people increasingly turning to the outdoors to socialize, exercise, and escape the 2020 news cycle, how might this be impacting wildlife and their habitat use? In a study published recently in Conservation Science and Practice, researchers used motion-triggered camera traps to examine how wildlife respond to human activity on the trails that bisect their habitat.

The researchers captured images of wildlife and humans in South Chilcotin Mountains Provincial Park in British Columbia. By strategically placing the cameras along trails, they identified 60 wildlife species. But the most common species recorded, by far, was humans.

Camera traps embed data such as the time and date on each photo. This lets the researchers calculate the time taken for a species to return after a human has passed through. 

Focusing on the 13 most frequent species — including coyotes, bears, moose, and wolves — the researchers found that all avoided humans on trails, but appeared to have a stronger aversion to mountain bikes and motorized vehicles than to hikers and horseback riders. In fact, and somewhat surprisingly, mountain bikes appeared to exhibit the strongest avoidance response in both moose and grizzlies.

By dissecting how species react to human activity, we can better incorporate this information into land-use planning and conservation efforts. Particularly sensitive species can be protected by limiting new trails in their habitat, or by restricting the most disturbing activities during sensitive periods (such as nesting season).

Researchers have reversed Parkinson's disease in mice

Infecting astrocytes with a virus made them develop into neurons

Ellie Tanimura

Neurobiology

Parkinson’s Disease is a movement disorder caused by the progressive loss of dopamine neurons in a brain-region called the substantia nigra (SN). Current treatments only relieve symptoms temporarily because they don't reverse what causes them: the loss of neurons. 

In a study recently published in Nature, researchers demonstrated that it is possible to reverse neuronal loss by converting astrocytes (helper brain cells) into neurons. They did so by injecting an astrocyte-targeting virus into the brains of mice. The simple virus suppressed the production of a protein called PTB, which blocks astrocytes from making neuronal proteins. 

With lower levels of PTB, these infected astrocytes could produce neuronal proteins, and became increasingly similar to neurons. Eventually, the former astrocytes were structurally and functionally indistinguishable from their neuronal counterparts! Following this conversion, researchers not only saw a significant restoration of dopamine neurons in the SN, but a full correction of movement symptoms in the mice. 

As bizarre as growing back a part of your brain sounds, the discovery of this new technique has transformed the idea of reversing Parkinson’s disease from a fantasy to a potential reality. 

Golden-collared manakins change choreography when the environment shifts

These bright yellow birds have elaborate courtship dances. Can they learn to do them differently?

Sukanya Ramani

Animal Behavior and Evolutionary Biology

Prayoga Education Research Centre

Males of many bird species perform elaborate courtship displays and dances that entice females into mating. This ritual acts as a precursor for females to choose males with “superior” characteristics, such as the ability to survive harsh environmental conditions, that she can ultimately pass on to her future offspring. 

Male golden collared manakins (Manacus vitellinus) are no exception — in fact, they have one of the most acrobatic courtship rituals among birds. They hop quickly from tree to tree in a consistent pattern within their display courts, a dance culminating in the final courtship element that is performed on a specific tree (the mating sapling) to win the chance to copulate with a nearby female. In a new paper published in Animal Behavior, scientists asked whether this consistent courtship behavior changes with a sudden change in the environment. In other words, do the birds adapt their dances when the layouts of their display courts change? 

The researchers first set out to measure different attributes of a courtship display, such as its duration and the speed of the courtship elements, from each of eight males. This was the pre-test phase. During the test phase, they placed a piece of bark on the mating sapling which was big enough so that the males wouldn’t be able to move it. They again measured the time taken for the courtship elements to be performed before the males perched onto an alternative mating sapling. They repeated the experiment at two different times each day for four consecutive days. Finally, in the post test phase, they removed the bark to see if the males came back to the original mating sapling or they continued using the alternative mating sapling. 

They found that the male manakins repeated a courtship element of the dance to buy time into choosing an alternative mating sapling, thereby showing behavioral flexibility. Some males went back to the original mating sapling in the post-test phase, and some alternated between the original and alternate saplings. Further research would help in showing why some males prefer going back to the original sapling while some prefer both, and what this meant for their mating success with their female audiences.

What will dexamethasone do to President Trump?

The cognitive and immunological effects of steroids face a test at a critical point in Trump's illness

Max G. Levy

Science and Health Journalism and Chemical Engineering

The president has had a life-threatening, infectious disease for over a week, and he and his doctors haven’t been very transparent about the timeline and course of his affliction. In lieu of detailed disclosures, reporters have to piece together his condition based on the treatments he’s been receiving. 

Trump was started off on an experimental therapeutic — an antibody cocktail — and then advanced to another — remdesivir. The other biomolecules coursing through Donald Trump's system (and this week's headlines) are corticosteroids, called dexamethasone.

You may have heard of cytokine storms, where the body's immune response to severe COVID-19 bombards healthy cells, making the illness worse. Trump has been given dexamethasone, an immuno-supressant that doctors prescribe to temper that effect. Unlike the other experimental treatments, dexamethasone is common and somewhat easy to access. However, it is rarely administered to a patient with a case as (self-)reportedly mild as Donald Trump’s.  In an interview with New York Magazine's Intelligencer, the co-author of a recent study testing dexamethasone elaborates:

James D. Walsh: Is there any reason to administer steroids to a patient who isn’t a severe case?
Bryan McVerry: I don’t think so. I don’t think that steroids are a preventive treatment in terms of progression of COVID-19 and if you look at the data from the recovery trial, which was the study published out of the U.K. in September, that was sort of the first steroid paper, a dexamethasone study, in patients with less severe disease, there was no clinical benefit, and potentially a trend towards worse clinical outcomes in patients who got it with milder disease. That didn’t reach statistical significance, but the odds ratio was headed in the wrong direction with the patients that they had recruited. I’m not sure you can draw any real conclusions from that except to say but there was no benefit — at least no trend towards benefit — on the population.

That lack of evidence is concerning as Trump heads into a critical point in the course of his illness. COVID-19 is known for being a bit of a roller coaster, with intermittent fevers, mysterious symptoms, and rapid declines. Abraar Karan, a physician with experience treating patients with COVID-19, told Monique Brouillette at Scientific American that some people have turned corners and left the hospital, only to  “come back feeling much sicker, with even worse oxygen levels and possibly other harm to the body’s organs.”

It is theoretically possible that the early steroid treatment may ward off a dangerous auto-inflammatory reaction. But beyond the inherent risks of immuno-supression, corticosteroids may also cause behavioral side effects in the President. Trump's cognitive and behavioral state has been a point of concern for years. Potent steroids such as dexamethasone are known to increase appetite, decrease restful sleep, and bring about heightened "maniacal" energy states.

As the nation enters the weekend, Speaker of the House Nancy Pelosi is rolling out a 25th amendment commission, Trump is boasting a miraculous recovery with a Fox News doctor, and the rest of us continue to wait and learn how biology will run its course. For better or worse, the side effects our president experiences may prove to have historical consequences. To my knowledge, “roid rage” has never been a factor in nuclear geopolitics. 

Female Barbary ground squirrels control their territory while males fly solo

New research uncovers the social lives of this African squirrel species

Jazmin Murphy

Ecology and Science Journalism

Since the 1980s, researchers have generally agreed that squirrels’ social structures are determined primarily by the females’ tendency to occupy a given territory. In a paper recently published in the Journal of Mammalogy, scientists took a closer look at the lives of Barbary ground squirrels to find out if they also exhibited this behavior. 

The researchers expected that, if the Barbary squirrels follow the behavioral patterns shown in other species of ground-dwelling squirrels in Africa, then the females would be “philopatric” (the ones who determine where the group lives) and males would be the dispersing sex, who must leave their family territories once they become adults to live alone or in all-male groups. 

Although the Barbary ground squirrel is native to Morocco and parts of Algeria, this study focused on an invasive population in the Canary Islands. The squirrels were live-trapped and marked for later identification, then released and observed through binoculars from morning to night. The relative stability of female and male groups was also measured by closely watching which individuals shared burrows each night, among other techniques that measured home range size and genetic relatedness. 

After spending about three breeding seasons with the squirrels, the research team had their answers. They concluded that the Barbary ground squirrels' social organization was just as they predicted. Interestingly, though, adult male and female squirrels share the same spaces during the day, but sleep separately at night.

In general, these squirrels were found to be far more gregarious (social) than initially thought, with surprising communal behavior from even lactating and nursing females. As the only living species in the genus Atlantoxerus — and an invasive one at that — the Barbary squirrel can now be better managed in areas where they are considered invasive and may endanger other wildlife. 

Working-class ants take the reins when the Indian jumping ant queen dies

This transition fundamentally changes their brains

Sree Rama Chaitanya

Molecular Biology

Instituto de Medicina Molecular

Social insect colonies, like those of ants and bees, are divided into castes based on distinct tasks such as reproduction, foraging, defense, and nest maintenance. Individuals belonging to different social castes show distinct molecular, physical, and behavior characters. These are usually established at the larval stage.    

But Indian jumping ants (Harpegnathos saltator) are unique. Unlike other ants, Indian jumping ants can switch castes when the reproductive queen dies. In these cases, about 70 percent of non-reproductive workers fight for dominance. Some successfully become reproductive queen-like ants, called gamergates, to ensure the continuation of the colony. This worker-gamergate transition incurs dramatic brain structural remodeling.

New research published in Science Advances has looked more closely at how the brains of gamergates compare to worker Indian jumping ants. By measuring gene expression changes in the brains of these ants at single-cell resolution, scientists discovered that the number of ensheathing glial cells — supportive neuronal cells essential to brain health and homeostasis — increases by 40 percent during the worker-gamergate transition. 

Not only that, when the scientists injured the brains of young Indian jumping ants (from stable or non-transitioning colonies) using needle punctures or antenna ablation, these same cells activated and expressed injury-responsive genes at a higher rate to cope with brain damage.

In ant colonies, reproductive queens live about ten times longer than workers, and gamergates about five times longer than workers. This study found that even older gamergates (~120 days in age) contained significantly more ensheathing glial cells than workers of the same age. (To put this into perspective, 120 days of Indian jumping ant life would translate to about 57 years on a human-age scale.) Older gamergates also expressed higher levels of injury-responsive genes after brain injury. Thus, scientists suggest that ensheathing glial cells protect gamergates from brain damage even in old age.

Yet, Indian jumping ants of all castes are genetically the same, so what makes them inherently distinct? The answer could be epigenetics: the inheritance of biological variation independent of the genetic sequence. Ants — and other social insects — provide a great example to study epigenetics and to explore the relative influence of nature and nurture on their lives.

Some people's immune systems control HIV infections without drugs

"Elite controllers" keep the deadly virus in check, and hide its DNA in a quiet section of the genome.

Hazel Walker

Immunology and Cell Biology

University of Cambridge

In what could be a world first, it appears that an HIV-1 patient may have completely eradicated their body of functional copies of the virus without requiring medical treatment. 

Researchers were studying a rare cohort of people known as "elite controllers," in which HIV-1 replication is suppressed by the immune system for many years. In order to better understand how this desirable control of the virus happens, researchers used advanced sequencing techniques to investigate the number of functional and non-functional copies of the virus and their location in the infected individual’s genomes. 

When compared with patients receiving the standard treatment of antiretroviral therapy, elite controllers had fewer viable copies of the virus in their genome. Furthermore, the viral DNA was stored in naturally inactive parts of the genome, rendering the virus mostly inert. 

The researchers also made another exciting finding: a patient known as "EC2" who had previously tested positive for HIV-1 appeared to have no functional copies of the virus despite analysis of over 1.5 billion of their cells. Provided viable virions are not lurking elsewhere, this could be the first instance of a natural cure.

Until now, cures came in the form of gruelling bone marrow transplants in the case of the "Berlin patient" and the "London patient" who simultaneously dealt with cancers. The Berlin patient, Timothy Ray Brown, was free from HIV for 13 years before he died in September of related leukemia.

This step forward in the understanding of elite controllers could help researchers developing therapies for the treatment of HIV-1, also highlighting that in some rare cases the immune system may be able to deal with the viral infection on its own.

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