The study, published in Nature Communications, reveals that several lizard groups evolved teeth with multiple tips (“cusps”) that allowed new plant-based diets and higher speciation rates — that is, how fast new species appear. Surprisingly, tooth evolution was more flexible in lizards and snakes than mammals, revealing a more nuanced view of tooth and dietary evolutionary adaptations in vertebrates.

Tooth shape is closely linked with diet

Scientists have richly documented the connection of tooth shape and diet in mammals, showing very diverse teeth fuelled their evolutionary success. But what about other toothed animals? The authors chose to study squamates, the group including lizards and snakes. “The teeth of squamates have received limited attention, even though they twice outnumber mammals in species numbers, and span many habitats and geographic ranges,” remarks Nicolas Di-Poï, Associate Professor at the Institute of Biotechnology, University of Helsinki.

The researchers performed comparative analyses on tooth shape and diet data for more than 500 living and fossil species. They found the ancestor to all snakes and lizards had simple peg-like teeth and fed on insects. Later, complex teeth bearing multiple cusps — similar to those of early mammals — evolved multiple times independently in different lizard lineages. The appearance of multiple-cusped teeth allowed some lizard groups to evolve more plant-rich diets, sometimes leading to even more complex teeth.

Lizards’ teeth evolution took two directions

The team also found that complex teeth and plant consumption provided an evolutionary advantage, as both traits favoured the appearance of new species. However, many lizard lineages also lost complex teeth to re-evolve the ancestral simple tooth morphology. “This came as a complete surprise,” says PhD candidate Fabien Lafuma from the University of Helsinki, “as complex teeth appear as a critical innovation for both squamates and mammals.”

The study suggests that all land-living vertebrates experience the same selective pressures for more cusps to increase plant consumption. Nevertheless, fundamental differences make squamates stand out. Contrary to mammals, tooth evolution was not unidirectional, and numerous lineages reduced complexity over time. This difference could stem from variations in tooth development, showing that minor molecular changes may produce widely different outcomes over evolutionary time scales. Lafuma concludes, “this work gives us a more nuanced understanding of how the same critical adaptation evolved in different vertebrate groups.”

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As the climate heats up and ocean temperatures rise, researchers expect to see significant changes in plankton distribution. Yet there are hardly any studies investigating where different species of plankton might thrive in the future.

Part of this knowledge gap has now been filled by a research team led by Fabio Benedetti and Meike Vogt, the former a postdoctoral researcher and the latter a senior scientist in Nicolas Gruber’s group at ETH Zurich, in collaboration with colleagues from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL).

The project team put together a new global dataset to create distribution maps for more than 860 species of phytoplankton and zooplankton based on various statistical algorithms and climate models. They then overlaid these maps to determine what plankton communities might look like in the future and where they might occur. The results of their work were recently published in the journal Nature Communications.

Warming drives diversity

Benedetti and his colleagues showed that the diversity of both phytoplankton and zooplankton can be expected to increase in the future across many regions, because warmer water generally tends to promote greater diversity.

However, at very high temperatures — that is, temperatures above 25 degrees Celsius — phytoplankton and zooplankton respond differently to warming: phytoplankton diversity continues to increase, while zooplankton diversity decreases. This will lead to a reduction in zooplankton diversity in the tropics.

Emergence of new communities

Plankton species from the tropics and subtropics will shift polewards and replace species that are adapted to cooler waters. This will give rise to numerous new communities that have never existed in these combinations before, a convergence of species that do not currently occupy the same habitat and whose interrelationships are not clearly aligned.

Researchers expect the biggest changes to occur in oceans at high and temperate latitudes — precisely those regions that are crucial for CO₂ fixation and fisheries.

“In some areas of the ocean, we will see a rise in species numbers that may, on the face of it, seem positive. But this boost in diversity could actually pose a serious threat to the existence and functioning of well-established marine ecosystems at higher latitudes,” says lead author Benedetti.

Marine ecosystems at high and mid-latitudes are currently dependent on species-poor plankton communities. The size distribution of plankton organisms also has an important influence on the quality of the ecosystem service.

To determine whether these factors change when plankton communities and thus their size distributions change, the researchers simulated the effects of climate change on the size structure of two important plankton groups, the diatoms and copepods. Data on the size of individual species is available for these organisms.

Smaller organisms replace larger ones

Using the simulations, the scientists demonstrated that the quality of the habitat increases for smaller organisms, while it decreases for the larger ones. Therefore, plankton communities could change, so too do the relative proportions of small and large species: smaller organisms become more abundant and numerous, especially at high and temperate latitudes, while larger organisms decrease in number.

According to the researchers, this will affect the ecosystem services that plankton provide: if changes occur in the plankton’s species composition and size structure, this could have a negative impact on the ecological pyramid and thus on fish yields.

Plankton also play an important role in oceanic carbon fixation. Some of the carbon fixed by phytoplankton sinks to the deep ocean and is effectively removed from exchange with the atmosphere.

For example, the Arctic Ocean is currently home to phytoplankton that are larger than those in tropical seas. Many of these have shells, and their excretions are also larger and heavier. As a result, both dead organisms and their excrement sink faster and to greater depths before the carbon they contain is decomposed back to CO₂. Dissolved in deeper waters, this CO₂ remains trapped in the depths for long periods of time due to density stratification and the slower circulation of the deep ocean.

If smaller species replace larger ones, this transfer of carbon to the deep ocean will decrease.

However, scientists cannot say exactly how significant these effects will be. “The only thing we can determine right now is how important certain areas of the ocean are today in terms of different ecosystem services and whether this provision of services will change in the future” Benedetti says.

Distribution shift well underway

Scientists have been observing shifts in plankton distribution since the Researchers have been observing that the distribution of plankton is shifting for several decades. The first systematic monitoring programme, the so-called Continuous Plankton Recorder (CPR), began in the North Atlantic in the 1930s. With the help of the CPR data, other researchers have recently been able to show that smaller copepods have displaced the larger species in the North Atlantic since the 1950s due to climate warming. This has also reduced the sequestration of atmospheric CO₂ in the deep sea.

Jellyfish, another type of zooplankton, are also migrating northwards. In 2005, Ireland detected a huge influx of tropical jellyfish, which devastated salmon farms along the coast. “Events like this show that shifts in plankton distribution are already well underway,” says co-author Meike Vogt.

“This is the largest metabolome analysis available on the brain, worldwide. It covers 1,547 identified metabolites, enabling analysis of many chemical conversions for energy, neurotransmitters or complex lipids in the brain,” said Professor Oliver Fiehn, director of the West Coast Metabolomics Center at the UC Davis Genome Center and senior author on the paper.

Metabolomics is the study of the chemical fingerprints of metabolism in living cells. It uses advanced high-throughput techniques to separate and identify all the different chemicals, or metabolites, present at a given time in a cell, tissue or organ. Alongside genomics, transcriptomics and proteomics, these techniques allow scientists to better understand what is happening inside cells and tissues.

Postdoctoral scholar Jun Ding, Fiehn and colleagues sampled mice at ages 3 weeks (adolescent), 16 weeks (early adult), 59 weeks (middle age) and 92 weeks (old age). They looked at ten separate brain regions with different functions. The new atlas can be used to better understand these different functions, Fiehn said.

The results show that the brain metabolome clearly is clearly distinct between large brain regions such as the brainstem, which controls vital functions such as breathing and blood pressure, from the cerebrum, which controls movements, speech and thinking, Fiehn said. In addition, specific sections showed high concentrations of metabolites associated with particular receptors, such as adenosine, ceramides and phospholipid ethers.

They did not find any significant metabolic differences between the brains male and female mice.

Metabolome of the aging brain

When the team compared animals of different ages, they found that overall, adult mice showed the greatest metabolic difference between brain sections. The differences between regions were less in adolescence and much less at very old ages.

“At very old age, energy functions appear to be less efficient, and the myelin sheaths that surround the axons, or wiring, of the brain change composition,” Fiehn said.

Lipid molecules especially showed large differences in aging and across brain regions. These lipids deserve specific investigation to see how they relate to changes in brain function, for example in signaling.

At very old age, the response system against oxidative stress becomes very active, while proteins start breaking down into peptides at an increased rate, he said. These changes are reflected in the metabolome.

The work was conducted in collaboration with the UC Davis Mouse Biology Program, led by Professor Kent Lloyd.

“This landmark paper clearly demonstrates the power of the laboratory mouse as a model to accelerate our understanding of brain metabolism, including and especially in humans,” Lloyd said.

The complete dataset is publicly available at https://mouse.atlas.metabolomics.us/.

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Snapshot of the lattice condition

“Our approach is different,” explains Dr. Régis Decker, lead author of the study. “We keep the sample at a certain temperature during the spectra acquisition. And we do that for many temperatures, from -120°C to 450°C for Gd — and much higher (1000°C) for previous experiments with Ni and FeNi. This allows us to quantify the effect of the phonons for each temperature on the ultrafast demagnetization, where the temperatures of the lattice, electrons and spins subsystems evolve with time. In other words, by placing the system at a certain temperature, we do a capture of the lattice condition at a given time after the ultrashort laser pulse and we measure there.”

Gadolinium examined

The element gadolinium has 4f and 5d electron orbitals, which both contribute to its ferromagnetic properties. The higher the temperature, the more the crystalline sample vibrates — and as physicists say: the more the population of phonons increases, and the more likely spin-flips are to occur due to the scattering of electrons with phonons from the crystal lattice.

Scattering rates distinguished

Using the method of inelastic X-ray scattering (RIXS), the physicists were not only able to determine the number of phonons at a given temperature, but also to distinguish the interactions between phonons and 4f- and 5d-electrons. Using the strict X-ray spectroscopic symmetry selection rules, the evaluation succeeded in distinguishing between the scattering rates of the 4f and 5d electrons.

5d electrons interact with phonons

The data show that there is hardly any scattering between the localized 4f electrons and phonons, but most of the scattering process takes place between 5d electrons and phonons, so that a spin-flip only occurs there. “Our approach evidences that the electron-phonon scattering, which is known to be one of the main trigger of ultrafast demagnetization, applies to the 5d electrons only. Interestingly, it also shows the presence of a temperature threshold, which depends on the material, below which this mechanism does not occur. This indicates the existence of another microscopic mechanism at lower temperature, as predicted by theory,” Decker explains.

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“Dogs share many similarities with humans, including physiological traits and the same environment. In addition, ADHD-like behaviour naturally occurs in dogs. This makes dogs an interesting model for investigating ADHD in humans,” says doctoral researcher Sini Sulkama.

Professor Lohi’s research group collected data on more than 11,000 dogs by conducting an extensive behavioural survey. Hyperactivity, impulsivity and inattention were examined using questions based on a survey utilised in human ADHD research. The goal of the study was to identify environmental factors underlying canine ADHD-like behaviour and potential links to other behavioural traits.

The dog’s age and gender as well as the owner’s experience of dogs make a difference

“We found that hyperactivity, impulsivity and inattention were more common in young dogs and male dogs. Corresponding observations relating to age and gender in connection with ADHD have been made in humans too,” says Jenni Puurunen, PhD.

Dogs who spent more time alone at home daily were more hyperactive, impulsive and inattentive than dogs who spent less time on their own.

“As social animals, dogs can get frustrated and stressed when they are alone, which can be released as hyperactivity, impulsivity and inattention. It may be that dogs who spend longer periods in solitude also get less exercise and attention from their owners,” Sulkama muses.

The researchers discovered a new link between hyperactivity and impulsivity, and the owner’s experience with dogs, as the two traits were more common in dogs who were not their owners’ first dogs. The causality of this phenomenon remains unclear.

“People may pick as their first dog a less active individual that better matches the idea of a pet dog, whereas more active and challenging dogs can be chosen after gaining more experience with dogs,” explains Sulkama.

Significant differences between breeds

Breeding has had a significant effect on the breed-specific behaviour of different dog breeds. Differences between breeds can also indicate genes underlying the relevant traits.

“Hyperactivity and impulsivity on the one hand, and good concentration on the other, are common in breeds bred for work, such as the German Shepherd and Border Collie. In contrast, a more calm disposition is considered a benefit in breeds that are popular as pets or show dogs, such as the Chihuahua, Long-Haired Collie and Poodle, making them easier companions in everyday life. Then again, the ability to concentrate has not been considered as important a trait in these breeds as in working breeds, which is why inattention can be more common among pet dogs,” Professor Lohi says.

Link to other behavioural problems

The study confirmed previously observed interesting links between hyperactivity, impulsivity and inattention, and obsessive-compulsive behaviour, aggressiveness and fearfulness. ADHD is also often associated with other mental disorders and illnesses. For example, obsessive-compulsive disorder (OCD) often occurs in conjunction with ADHD. In dogs, OCD-like obsessive-compulsive behaviour can appear as, among other things, tail chasing, continuous licking of surfaces or themselves, or staring at ‘nothing’.

“The findings suggest that the same brain regions and neurobiological pathways regulate activity, impulsivity and concentration in both humans and dogs. This strengthens the promise that dogs show as a model species in the study of ADHD. In other words, the results can both make it easier to identify and treat canine impulsivity and inattention as well as promote ADHD research,” Sulkama sums up.

Probably not, if annual influenza vaccination rates are any indication, especially if you’re under the age of 65. According to a Houston Methodist review published in the Journal of the American Heart Association, Americans with heart disease continue to have low vaccination rates every year despite higher rates of death and complications from influenza.

The flu vaccination rate for American adults who are less than 65 years of age and have heart disease is less than 50%, compared to 80% in older adults with heart disease.

“It seems that younger Americans with high-risk conditions have not gotten the same memo that their older counterparts have received about the importance of getting the influenza vaccine,” says Dr. Priyanka Bhugra, internal medicine specialist at Houston Methodist and lead author of the JAHA article. “That’s dangerous, considering people with heart conditions are particularly vulnerable to influenza-related heart complications, whether they’ve reached retirement age or not.”

It’s well-known that the flu can lead to significant respiratory symptoms such as pneumonia, bronchitis and bacterial infection of the lungs. The virus’ effects on the heart have historically been harder to parse out, in part because many patients already have a known predisposition to cardiac events and in part because the cardiac event often occurs weeks after the onset of the flu.

But here’s what recent research has shown:

• Cardiovascular deaths and influenza epidemics spike around the same time.
• Patients are six times more likely to experience a heart attack the week after influenza infection than they are at any point during the year prior or the year after the infection.
• In one study looking at 336,000 hospital admissions for flu, 11.5% experienced a serious cardiac event.
• Another study looking at 90,000 lab-confirmed influenza infections showed a strikingly similar rate of 11.7% experiencing an acute cardiovascular event.
• One in eight patients, or 12.5%, admitted to the hospital with influenza experienced a cardiovascular event, with 31% of those requiring intensive care and 7% dying as a result of the event, another study found.

The reason influenza stresses the heart and vascular system so much has to do with the body’s inflammatory response to the infection.

Inflammation occurs when your body’s “first responders” — white blood cells and what they produce in order to protect you — convene in an area and get to work fighting an infection, bacteria or virus. When you’re sick, you can typically feel the effects of these “combat zones” in the swelling, tenderness, pain, weakness and sometimes redness and increased temperature of your joints, muscles and lymph nodes.

The increased activity can also cause a traffic jam of sorts, leading to blood clots, elevated blood pressure and even swelling or scarring within the heart. The added stressors make plaque within your arteries more vulnerable to rupture, causing a blockage that cuts off oxygen to the heart or brain and results in heart attacks or strokes, respectively.

Additionally, non-cardiac complications from the viral illness, including pneumonia and respiratory failure, can make heart failure symptoms or heart arrhythmia much worse.

In short, the added stress on the cardiovascular system could be overwhelming to an already weakened heart muscle.

Because influenza viruses are constantly mutating, scientists alter the vaccine each year to match the likely prevalent strands. On average, it’s effective at preventing infection 40% of the time. While that might not sound great — especially in comparison to the highly effective mRNA COVID-19 vaccines — it’s enough to significantly lower the risk of severe illness in most people.

Lately, studies have been able to show that not only is the vaccine effective at protecting the general population and the most vulnerable age groups (over 65 and under 2) from severe cases of the flu, but it’s also protective against cardiovascular mortality as well, especially among the high-risk population.

Some of the recent findings:

• Adults who received the vaccine were 37% less likely to be hospitalized for the flu and 82% less likely to be admitted to the ICU because of it. Among people admitted to the hospital with the flu, those vaccinated were 59% less likely to be admitted to the ICU. Vaccinated patients admitted to the ICU spent four fewer days in the ICU than unvaccinated patients.
• Vaccination was associated with a lower risk of cardiovascular events (2.9% vs 4.7%) if the patient got the flu. Among the highest-risk patients with more active coronary disease, vaccination was associated with considerably better outcomes.
• Patients admitted to the hospital with acute coronary syndrome were randomly assigned to either receive a flu vaccine or not before discharge. Major cardiovascular events occurred less frequently in the vaccine group than the control group (9.5% vs. 19%).

As a result of the demonstrated benefits conferred by influenza vaccination and the risks posed by flu infection among those with cardiovascular disease, the CDC and numerous other international societies strongly recommend annual influenza vaccination in patients with cardiovascular disease.

Clinicians should ensure high rates of influenza vaccination, especially in those with underlying chronic conditions, to protect against acute cardiovascular events associated with influenza.

Unfortunately, many heart patients visit their cardiologist more frequently than their primary care providers, and cardiology practices typically do not provide flu vaccinations, though proposed recommendations may change in the future. Until then, it is incumbent upon both the cardiology provider and the primary care provider to communicate the increased risk to their patients and the importance of getting vaccinated.

For patients with heart conditions, there are two important steps you can take to reduce your risk:

• Make sure you do obtain your influenza vaccine from your local pharmacy or primary care provider. The earlier you get it, the better it is at protecting you, as you never know when the virus may begin to spread.
• Make sure you are taking your medications and following your recommended diet, exercise and stress reduction plans. If your heart condition is stable and you end up with the flu, chances are you’ll experience fewer, less severe complications than if your heart condition is poorly managed.

The team headed by Anne Bierbrauer, Professor Oliver Wolf and Professor Nikolai Axmacher from the RUB Institute of Cognitive Neuroscience describes the findings in the journal Current Biology, published online on 14 October 2021.

Different theories

“We usually have detailed images in your mind’s eye of stressful experiences, such as taking the driving test, even after many years,” says Oliver Wolf. “Whereas a walk through the park on the same day is quickly forgotten.” The neuroscientists at RUB would like to understand the reasons for this phenomenon.

Earlier studies and theoretical considerations had led to different predictions about how memories of stressful experiences differ from neutral ones: “One idea was that very different memory representations might have been the key to more powerful memories; on the other hand, there were indications that stress memories have resembled each other more closely,” explains Anne Bierbrauer. The current study provides evidence for the second theory.

Analysing stressful experiences in the lab

Unlike in many laboratory studies, the researchers set out to record the memory trace of a real event in their experiments, using the so-called Trier Social Stress Test for this purpose. This test requires the participants to speak in front of an application committee, all of whom wear a neutral expression and don’t give any positive feedback. The test unfailingly triggers stress in the participants.

During the job interview simulation, the committee used a number of everyday objects; for example, one of the committee members took a sip from a coffee cup. The control group was confronted with the same objects, but the participants were not subjected to any stress. One day later, the researchers showed the objects to participants in both groups while recording brain activity in a magnetic resonance imaging scanner. The stressed participants remembered the objects better than members of the control group.

The researchers analysed primarily the brain activity in the amygdala, a region whose main functions include emotional learning. They compared the neuronal traces of objects that had been used by the committee members in the stress situation with those of objects that hadn’t been used. The result was: the memory traces of objects that had been used resembled each other more closely than those of objects that hadn’t been used. This was not the case in the control group. In other words, the brain representations of the objects from the stressful situations were very closely linked, and they were thus clearly set apart from other experiences.

Stressful memories are based on their resemblance to the stressor

One day after the stress test, the researchers showed the participants not only pictures of the objects from the job interview, but also photos of members of the committee. The participants mainly remembered objects where the brain activity was similar to the activity triggered by the presentation of the committee members. “The committee members triggered the stress in the interview situation. Accordingly, it seems that the link between the objects and the stress triggers was crucial for the enhanced memory,” concludes Nikolai Axmacher.

The findings obtained in this study argue against the theory that stronger memories are triggered by memory representations that differ from each other as much as possible — at least when it comes to emotional or stressful memories. Rather, the mechanism that reinforces emotional memories appears to be rooted in the fact that the important aspects of the episode are linked at the neural level and become more closely related to the stress trigger. “This result could be an important building block to better understand emotional and traumatic memories,” points out Anne Bierbrauer.

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