Which animals can best withstand climate change?

Peer-Reviewed Publication

UNIVERSITY OF SOUTHERN DENMARK

Extreme weather such as prolonged drought and heavy rainfall is becoming more and more common as the global average temperature rises – and it will only get worse in the coming decades. How will the planet’s ecosystems respond?

- That is the big question and the background for our study, said biologist John Jackson, who, together with his biologist colleagues Christie Le Coeur from the University of Oslo and Owen Jones from University of Southern Denmark, authored a new study, published in eLife (https://elifesciences.org/articles/74161).

John Jackson is now at Oxford University but was at the University of Southern Denmark when the study was made. Owen Jones is associate professor at the Department of Biology, University of Southern Denmark.

Llama, moose and elephant

In the study, the authors analyzed data on population fluctuations from 157 mammal species from around the world and compared them with weather and climate data from the time the animal data were collected. For each species there are 10 or more years of data.

Their analysis has given them an insight into how populations of animal species have coped at times of extreme weather: Did they become more, or less, numerous? Did they have more or fewer offspring?

- We can see a clear pattern: Animals that live a long time and have few offspring are less vulnerable when extreme weather hits than animals that live for a short time and have many offspring. Examples are llamas, long-lived bats and elephants versus mice, possums and rare marsupials such as the woylie, said Owen Jones.

Less affected by extreme weather:

African elephant, Siberian tiger, chimpanzee, greater horseshoe bat, llama, vicuña, white rhinoceros, grizzly bear, American bison, klipspringer, Schreibers's bat.

More affected by extreme weather:

Azara's grass mouse, olive grass mouse, elegant fat-tailed mouse opossum, Canadian lemming, Tundra vole, Arctic fox, stoat, common shrew, woylie, arctic ground squirrel.

Quick drop – but also quick boom

Large, long-lived animals are better able to cope with conditions like prolonged drought; their ability to survive, to reproduce and to raise their offspring is not affected to the same extent as small, short lived animals. They can, for example, invest their energy into one offspring, or simply wait for better times when conditions become challenging.

On the other hand, small short-lived rodents have more extreme population changes in the short term. In the event of a prolonged drought, for example, large parts of their food base may disappear more rapidly: insects, flowers, fruits, and they are left to starve because they have limited fat reserves.

The populations of these small mammals may also boom to take advantage when conditions improve because, in contrast to large mammals, they can produce many offspring.

Not the same as risk of extinction

- These small mammals react quickly to extreme weather, and it goes both ways. Their vulnerability to extreme weather should therefore not be equated with a risk of extinction, said John Jackson.

He also reminds us that the ability of an animal species to withstand climate change must not stand alone when assessing the species’ vulnerability to extinction:

- Habitat destruction, poaching, pollution and invasive species are factors that threaten many animal species - in many cases even more than climate change, he emphasized.

The animals we don't know much about

The researchers' study not only gives an insight into how these specific 157 mammal species react to climate changes here and now. The study can also contribute to a better general understanding of how the planet's animals will respond to ongoing climate change.

- We expect climate change to bring more extreme weather in the future. Animals will need to cope with this extreme weather as they always have. So, our analysis helps predict how different animal species might respond to future climate change based on their general characteristics – even if we have limited data on their populations, said Owen Jones.

An example is the woylie, a rare Australian marsupial. Biologists do not know very much about this species, but because it shares a similar life style with mice – that is, it is small, lives for a short time and reproduces quickly – it can be predicted that it will respond to extreme weather in a similar way to mice.

Entire ecosystems will change

- In the same way, there are lots of animal species that we don't know very much about, but whose reaction we can now predict, explained John Jackson.

In this way, the researchers expect that the ability of different animal species to adapt to climate change is related to their life strategy, and this can help us predict ecological changes:

As habitat suitability changes due to climate change, species may be forced to move to new areas as old areas become inhospitable. These shifts depend on species’ life strategies and can have big impacts on ecosystem function.

The work has been supported by Independent Research Fund Denmark.

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JOURNAL

eLife

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Animals

ARTICLE TITLE

Life history predicts global population responses to the weather in terrestrial mammals

Scientists identify liquid-like atoms in densely packed solid glasses

Peer-Reviewed Publication

CHINESE ACADEMY OF SCIENCES HEADQUARTERS

 

IMAGE: REVEALING LIQUID-LIKE ATOMS IN METALLIC GLASSES VIA DYNAMICS EXPERIMENTS view more 

CREDIT: INSTITUTE OF PHYSICS

Metallic glass is an important advanced alloy, holding promise for broad engineering applications. It appears as a solid form in many aspects, with beautiful metal appearance, exceeding elasticity, high strength, and a densely packed atomic structure. 

However, this all-solid notion has now been challenged. Prof. BAI Haiyang from the Institute of Physics of the Chinese Academy of Sciences (CAS) has recently shown the existence of liquid-like atoms in metallic glasses. These atoms inherit the dynamics of high-temperature liquid atoms, revealing the nature of metallic glasses as part-solid and part-liquid. 

Results were published in Nature Materials. 

Condensed matter can generally be classified into solid and liquid states. Under extreme conditions or in specific systems, matter exists in special states that simultaneously exhibit some properties of both solids and liquids. In this case, solids may contain rapidly diffusing, liquid-like atoms that can move fast even at low temperatures. 

For example, ice enters a "superionic" state under high pressure at high temperatures. In this state, H atoms can diffuse freely while O atoms are fixed in their sublattices. Such special states are also observed in Earth's inner core and in the Li-conducting materials of advanced batteries, which are drawing growing attention in science and engineering. 

In this study, the researchers revealed that liquid-like atoms exist in densely packed metallic glasses. Combining extensive dynamical experiments and computer simulations, they found that when the viscosity of a liquid deviates from Arrhenius behavior, not all atoms take part in cooperative flow and subsequent solidification. In fact, some atoms can maintain liquid Arrhenius behavior even when the system is cooled down to a glass state, thus appearing as persistent liquid-like atoms that lead to fast relaxation at rather low temperatures. 

"A glassy solid is essentially mostly solid and a small part liquid. Even at room temperature, liquid-like atoms in a glassy solid can diffuse just as easily as in its liquid state, with an experimentally determined viscosity as low as 107 Pa·s, while the viscosity of the solid part is larger than 1013 Pa·s," said Prof. BAI. 

These findings provide a clearer microscopic picture of glasses. This new picture can help scientists better understand how the properties of glass materials are related to their dynamics. For example, liquid-like atoms control the anelasticity of glasses and may affect their ductility. 

Moreover, the strong relationship between liquid-like atoms and disordered structure also has implications for studying the topological origin of fast diffusion in solids, such as superionic-state matters and ion conductors. 

This study was supported by the National Science Foundation of China, the Natural Science Foundation of Guangdong Province, and the Strategic Priority Research Program of CAS, among others. 

CAPTION

isualization of Liquid-like atoms in Al90La10 MG at 300K by MD simulations

CREDIT

Institute of Physics

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JOURNAL

Nature

DOI

10.1038/s41563-022-01327-w 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Liquid-like atoms in dense-packed solid glasses

ARTICLE PUBLICATION DATE

15-Aug-2022

1. Is Glass A Solid Or An Extremely Slow Moving Liquid?

   https://www.sciencedaily.com/releases/2007/08/070809130014.htm

   2007-08-13

2. Fact or Fiction?: Glass Is a (Supercooled) Liquid
   

   https://www.scientificamerican.com/article/fact-fiction-glass-liquid

   2007-02-22 · For practical purposes, such as holding a drink, glass is like a solid, Ediger says, although a disorganized one. Like liquids, these disorganized solids can flow, albeit very slowly. Over long...

FRONT PAGE ABOVE THE FOLD

First completely robot-supported microsurgical operations on humans

Münster surgeons use new operating method for the first time anywhere in the world

Business Announcement

UNIVERSITY OF MÜNSTER

 

IMAGE: DR. MAXIMILIAN KÜCKELHAUS PRESENTS THE NEW METHOD IN A DRY-RUN TRAINING SESSION. THE OPERATIONS ROBOT (RIGHT) IS NETWORKED WITH A ROBOTIC MICROSCOPE (LEFT). view more 

CREDIT: WWU - PETER LESSMAN

It is a great success for robotic microsurgery not only in Münster but worldwide – both for medicine and for science: a team led by scientists Dr. Maximilian Kückelhaus and Prof. Tobias Hirsch from the Centre for Musculoskeletal Medicine at the University of Münster has carried out the first completely robot-supported microsurgical operations on humans. The physicians used an innovative operating method in which a new type of operations robot, designed especially for microsurgery, is networked with a robotic microscope. This approach makes it possible for the operating surgeon to be completely taken out of the operating area. The use of robots for clinical research is undertaken in collaboration with Münster University Hospital and Hornheide Specialist Clinic.

The experts have been using this method for a good two months. So far, five operations have been successfully performed, with many more set to follow. “This new method for operations enables us to work with a much higher degree of delicacy and precision than is possible with conventional operating techniques,” says Maximilian Kückelhaus. “As a result, less tissue is destroyed and patients recover faster.” The specialists use the method for example on patients with breast cancer who need complex breast reconstructions, or after accidents in which patients need tissue transplants. With the aid of the robot and the robotic microscope, the microsurgeons can for example join up again the finest anatomical structures such as blood vessels, nerves or lymphatic vessels, which often have a diameter of only 0.3 millimetres.

During the operation, the robot – the so-called Symani Surgical System – adopts human hand movements via an electromagnetic field and joysticks. The robot carries out the operating surgeon’s movements, reduced in size by up to 20 times, via tiny instruments and, in doing so, completely eliminates any shaking present in (human) hands. A robotic microscope is connected to the operation robot, and this microscope shows the area being operated on via a so-called 3D Augmented Reality Headset with two high-resolution monitors. This headset contains a binoculars which are able to combine the real world with virtual information. In this way, the surgeon’s head movements can be recorded and transferred to the robot, making even complicated viewing angles possible on the area being operated on. In addition, the operating surgeon can access a variety of menus and perform functions with the robot without using his or her hands.

The new technology also has the advantage that operating surgeons can adopt a relaxed posture – whereas they otherwise have to perform operations in a strenuous posture over a period of several hours. “As we can now operate on patients in a remote fashion, we have much better ergonomics,” says Tobias Hirsch, who holds the Chair of Plastic Surgery at Münster University. “This in turn protects us from fatigue, and that means that our concentration can be maintained over a period of many hours. In initial studies involving the systems, before they were used in operations, we were already able to confirm the positive effects on the quality of operations and on ergonomics.” During training with students and established microsurgeons, the physicians were able to demonstrate that, while using the robotic system, the learning curve, the handling of the instruments, and the ergonomics all demonstrated an improvement over conventional operating techniques.

In the coming weeks and months, Maximilian Kückelhaus and Tobias Hirsch will be performing further operations and, in the process, collect data that they will be evaluating in scientific studies. Important issues to be addressed are, in particular, improvements to the quality of operations and to ergonomics. “Our hope is that with this new method we can not only perform operations with a greater degree of precision and safety – but also, in the case of the tiniest structures, go beyond limits imposed by the human body. Not having to be at the operating table can also mean that one day the operating surgeon will no longer have to be physically present. An expert might be able to perform special operations at any one of several locations – without having to travel and be there in person,” says Maximilian Kückelhaus, looking into the future.

Funding

For the development of, and the clinical trials for, this new method of treatment, Maximilian Kückelhaus received funding from the European Union initiative entitled “Recovery Assistance for Cohesion and the Territories of Europe”.

Robotic kidney cancer surgery shows desirable outcomes in study

Peer-Reviewed Publication

UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER AT SAN ANTONIO

 

IMAGE: IN THIS ILLUSTRATION, A MASS (DEPICTED AS JAGGED) IS SHOWN ON A KIDNEY (LEVEL I, AT LEFT). THE TUMOR EXTENDS UP THE INFERIOR VENA CAVA VEIN (BLUE) TO THE LIVER (LEVEL III) AND APPROACHES THE HEART (LEVEL IV). SURGICAL CLAMPS TO CONTROL THE TUMOR ARE SHOWN IN RED AND YELLOW. A ROBOTIC SURGICAL INSTRUMENT IS SHOWN IN BLACK. IMAGE COURTESY DHARAM KAUSHIK, MD/JOURNAL OF UROLOGY. view more 

CREDIT: DHARAM KAUSHIK, MD/JOURNAL OF UROLOGY

SAN ANTONIO (Aug. 19, 2022) — Kidney cancer is not always confined to the kidney. In advanced cases, this cancer invades the body’s biggest vein, the inferior vena cava (IVC), which carries blood out of the kidneys back to the heart. Via the IVC, cancer may infiltrate the liver and heart. The Mays Cancer Center at The University of Texas Health Science Center at San Antonio (UT Health San Antonio) is one of the high-volume centers in the U.S. with surgical expertise in treating this serious problem. The Mays Cancer Center is San Antonio’s National Cancer Institute-designated Cancer Center.

In a study featured on the cover of the Journal of Urology (Official Journal of the American Urological Association), researchers from the Mays Cancer Center and Department of Urology at UT Health San Antonio show that robotic IVC thrombectomy (removal of cancer from the inferior vena cava) is not inferior to standard open IVC thrombectomy and is a highly safe and effective alternative approach. The affected kidney is removed along with the tumor during surgery, which is performed at UT Health San Antonio’s clinical partner, University Hospital.

Harshit Garg, MD, urologic oncology fellow in the Department of Urology, is first author of the study, and Dharam Kaushik, MD, urologic oncology fellowship program director, is the senior author. Kaushik is an associate professor and the Stanley and Sandra Rosenberg Endowed Chair in Urologic Research at UT Health San Antonio.

The open surgery requires an incision that begins 2 inches below the ribcage and extends downward on both sides of the ribcage. “It looks like an inverted V,” Kaushik said. Next, organs that surround the IVC, such as the liver, are mobilized, and the IVC is clamped above and below the cancer. In this way, surgeons gain control of the inferior vena cava for cancer resection.

“Open surgery has an excellent success rate, and most cases are performed in this manner,” Kaushik said. “But now, with the robotic approach, we can achieve similar results with smaller incisions. Therefore, we need to study the implications of utilizing this newer approach.”

The study is a systematic review and meta-analysis of data from 28 studies that enrolled 1,375 patients at different medical centers. Of these patients, 439 had robotic IVC thrombectomy and 936 had open surgery. Kaushik and his team collaborated with Memorial Sloan Kettering Cancer Center, New York; Cedars-Sinai Medical Center, Los Angeles; and the University of Washington, Seattle, to perform this study.

“We pulled the data together to make conclusions because, before this, only small studies from single institutions had been conducted to compare the IVC thrombectomy approaches,” Kaushik said.

Findings

The results are encouraging and indicate further study of robotic IVC thrombectomy is warranted. The robotic approach in comparison with open was associated with:

• Fewer blood transfusions: 18% of robotic patients required transfusions compared to 64% of open patients.
• Fewer complications: 5% of robotic patients experienced complications such as bleeding compared to 36.7% of open thrombectomy patients.

These large, technically challenging surgeries last eight to 10 hours and involve a multidisciplinary team of vascular surgeons, cardiac surgeons, transplant surgeons and urologic oncology surgeons, Kaushik said.

“This study is the largest meta-analysis analyzing the outcomes of robotic versus open IVC thrombectomy,” Kaushik said. “In more than 1,300 patients, we found that overall complications were lower with the robotic approach and the blood transfusion rate was lower with this approach.

“That tells us there is more room for us to grow and refine this robotic procedure and to offer it to patients who are optimal candidates for it,” Kaushik said. “Optimal candidacy for a robotic surgery should be based on a surgeon’s robotic expertise, the extent and burden of the tumor, and the patient’s comorbid conditions. The open surgical approach remains the gold standard for achieving excellent surgical control.”

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A Decade of Robotic-Assisted Radical Nephrectomy with Inferior Vena Cava Thrombectomy: A Systematic Review and Meta-Analysis of Perioperative Outcomes

Harshit Garg, Sarah P. Psutka, Abraham Ari Hakimi, Hyung L. Kim, Ahmed M. Mansour, Deepak Pruthi, Michael A. Liss, Hanzhang Wang, Christine S. Gaspard, Chethan Ramamurthy, Robert S. Svatek, Dharam Kaushik

First published: June 28, 2022, Journal of Urology

https://pubmed.ncbi.nlm.nih.gov/35762219/

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The Mays Cancer Center at UT Health San Antonio is one of only four National Cancer Institute-designated Cancer Centers in Texas. The Mays Cancer Center provides leading-edge cancer care, propels innovative cancer research and educates the next generation of leaders to end cancer in South Texas. Visit www.cancer.uthscsa.edu.

Stay connected with The University of Texas Health Science Center at San Antonio on Facebook, Twitter, LinkedIn, Instagram and YouTube.

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JOURNAL

The Journal of Urology

DOI

10.1097/JU.0000000000002829 

METHOD OF RESEARCH

Systematic review

SUBJECT OF RESEARCH

People

ARTICLE TITLE

A Decade of Robotic-Assisted Radical Nephrectomy with Inferior Vena Cava Thrombectomy: A Systematic Review and Meta-Analysis of Perioperative Outcomes

Early blood tests predict death, severe disability for traumatic brain injury

In the study, the method predicted poor outcomes six months after injury with high accuracy

Peer-Reviewed Publication

MICHIGAN MEDICINE - UNIVERSITY OF MICHIGAN

 

IMAGE: A GRAPHIC OF TBI WITH BLOOD TEST VIALS. view more 

CREDIT: JUSTINE ROSS, MICHIGAN MEDICINE

A study finds that blood tests taken the day of a traumatic brain injury can predict which patients are likely to die or survive with severe disability, allowing clinicians to make decisions earlier on possible treatment of TBI. 

Researchers from Michigan Medicine, the University of California San Francisco and the University of Pennsylvania analyzed day-of-injury blood tests of nearly 1,700 patients with TBI. Results published in The Lancet Neurology reveal that higher values of two protein biomarkers, GFAP and UCH-L1, are associated with death and severe injury.

This is the first study to examine the association between biomarker levels of these two proteins and all-cause mortality following TBI, says first author Frederick Korley, M.D., Ph.D., associate professor of emergency medicine at the University of Michigan Medical School.

“Early and accurate prediction of TBI outcomes will help clinicians gauge how severe a brain injury is and inform how best to counsel family members about care for their loved ones with brain injury and what to expect with regards to their recovery,” Korley said. “It will also help researchers more precisely target promising TBI therapeutics to the right TBI patients.”

The U.S. Food and Drug Administration cleared the use of GFAP and UCH-L1 in 2018 to help clinicians decide whether to order CT scans for mild traumatic brain injury.

Researchers measured the proteins using two devices from Abbott Laboratories, the i-STAT Alinity and the ARCHITECT. Results were compared to evaluations made six months after injury using the Glasgow Outcome Scale-Extended, a system that grades the functional status of TBI patients.

Investigators found that compared to those with GFAP values in the bottom 20th percentile, those with GFAP values in the top 20th percentile had a 23 times higher risk of death during the subsequent six months. Similarly, compared to those with UCH-L1 values in the bottom 20th percentile, those with UCH-L1 values in the top 20th percentile had a 63 times higher risk of death during the subsequent 6 months.

“Modern trauma care can result in good outcomes in what we had once believed were non-survivable injuries,” said co-senior author Geoffrey Manley, M.D., Ph.D., professor and vice chair of neurosurgery at UCSF. “These blood tests are both diagnostic and prognostic, as well as easy to administer, safe and inexpensive.”

While the method is promising for determining poor outcomes in moderate and severe TBI, researchers say more must be done to examine its role in mild cases.

“As a next step, the TRACK-TBI team is planning a clinical trial that will examine the efficacy of promising therapeutic agents that may help traumatic brain injury patients recover quickly,” Korley said. “As part of this clinical trial, these biomarkers will be used as an objective method for selecting the right patients to enroll in this trial. We will also use these biomarkers to monitor individual patient response to these promising therapeutics.”

Korley previously consulted for Abbott Laboratories. Korley and Robertson have received research funding from Abbott Laboratories. Manley received research funding from a collaboration between Abbott Laboratories and the U.S. Department of Defense. Diaz-Arrastia consulted for MesoScale Discoveries, BrainBox Solutions, and NovaSignal. All other authors and collaborators declare no competing interests.

Paper cited: “Prognostic value of day-of-injury plasma GFAP and UCH-L1 concentrations for predicting functional recovery after traumatic brain injury in patients from the US TRACK-TBI cohort: an observational cohort study,” The Lancet Neurology DOI: 0.1016/S1474-4422(22)00256-3

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JOURNAL

The Lancet Neurology

DOI

10.1016/S1474-4422(22)00256-3 

METHOD OF RESEARCH

Randomized controlled/clinical trial

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Prognostic value of day-of-injury plasma GFAP and UCH-L1 concentrations for predicting functional recovery after traumatic brain injury in patients from the US TRACK-TBI cohort: an observational cohort study

ARTICLE PUBLICATION DATE

10-Aug-2022

COI STATEMENT

Korley previously consulted for Abbott Laboratories. Korley and Robertson have received research funding from Abbott Laboratories. Manley received research funding from a collaboration between Abbott Laboratories and the U.S. Department of Defense. Diaz-Arrastia consulted for MesoScale Discoveries, BrainBox Solutions, and NovaSignal. All other authors and collaborators declare no competing interests.

Certain environment authority decisions are based on trust in citizen data

UNIVERSITY OF GOTHENBURG

19-AUG-2022

County administrative boards and the Swedish Forest Agency use species sightings reported by the public to make various environmental decisions. This is done largely on the basis of trust between a few actors who determine which sightings can be used as a basis for decisions. This is shown by researchers at the University of Gothenburg who have investigated how citizen science is used in Swedish society.

In a new study, Dick Kasperowski and Niclas Hagen, both theorists of science, have looked at how county administrative boards and the Swedish Forest Agency use reports in Artportalen – a web portal for species sightings of Sweden's plants, animals and fungi, to which anyone can report species. More than 90 million sightings are registered, and it is now one of the largest species portals in the world. This form of citizen science creates a very valuable knowledge bank for Swedish nature conservation as regards species distribution. As Artportalen is used by several authorities and courts, it also provides researchers with a unique opportunity to understand how citizen data is used.

The study is based on interviews with officials around Sweden who use citizen’s sightings to make decisions on land and water issues. This may concern logging or exploiting land and water areas for road construction, wind turbines, emissions, industrial installations, or other types of interventions that have consequences for the environment. The researchers have studied how officials relate to these sightings when creating basis for such cases.

‘We saw that it is a small number of people who determine which reported sightings will influence decisions about the environment and the use of land and water, and that need not be a problem in itself, but to put it more bluntly, a sighting is not certain just because it has been reported; it is verified through a series of different arrangements and networks where technologies and people interact, and where trust has to be built,’ says Dick Kasperowski.
 
There are complex interactions between officials' interpretations of legal texts, the use of computer programmes to map sightings, lists of endangered species, tools to determine the time and place of sightings, and validations by committees within Artportalen. But it may also be that an official personally knows the reporter, or local knowledge of members of an ornithological society that is highly valued by agency staff that is involved.

‘Not infrequently, some submitted data is uncertain, and that's where trust comes in. We also show that trust is not evenly distributed in this system, but more concentrated in certain actors, which is due to interpersonal relationships that have developed over time,’ says Niclas Hagen.

The knowledge base that is to help our leaders make more informed decisions about major societal challenges, climate, and species preservation depends on many people getting involved, as is the case with Artportalen.

‘However, the validity of sightings is assessed by a small number of officials, members of evaluation committees and environmental lawyers. This means that the existing high expectations for citizen science to democratise science, in an almost representative sense, cannot be met. The higher up the decision-making pyramids we go, the fewer the assessors become, and the more resources they have. This is an issue that needs to be studied in more detail,’ says Dick Kasperowski.

International research shows that participants in citizen science are generally better educated, upper middle class, and middle-aged or older. In the case of large long-term species observation projects, they are dominated by individuals who identify as male, with an interest in certain species, particularly birds.
‘We will now move on with studies of how inequalities can manifest in citizen science,’ says Niclas Hagen.

The study also shows that Artportalen is used in environmental activism to pursue certain environmental issues, such as when there are plans for logging on sites deemed to be of high conservation value. This has resulted in cases in land and environmental courts against Swedish authorities for not complying with national or international environmental laws and conventions.

‘How this can change the political processes for difficult environmental issues is far beyond the scope of this article, but is definitely a question for future research,’ says Niclas Hagen.

The study is presented in Social Studies of Science and is titled Making particularity travel: Trust and citizen science data in Swedish environmental governance.

The article can be freely downloaded via this link: https://journals.sagepub.com/doi/pdf/10.1177/03063127221085241

The research on which the study is based has been conducted within the Citizen Science: collecting and using data for societal change project, funded by Formas (Registration no 2017 - 01212).

Contact:

• Dick Kasperowski, phone: 0766 181 945, email: dick.kasperowski@gu.se
• Niclas Hagen, phone: 031 786 5056, email: niclas.hagen@gu.se

Mosquitoes have a bizarre sense of smell, study finds

The unconventional way mosquitoes process odors could help explain why they are so good at finding humans to bite

Peer-Reviewed Publication

BOSTON UNIVERSITY

If you’ve ever sprayed yourself head to toe in bug repellent, yet still felt like a mosquito magnet, it will come as no shock to you that mosquitoes are very, very good at finding humans to bite. One key factor in this superpower is their keen sense of smell, or olfaction, which relies on the olfactory system. 

“Mosquitoes are highly specialized,” says Meg Younger, a Boston University College of Arts & Sciences assistant professor of biology who studies mosquito olfaction. These relentless, buzzing creatures are designed to find us, bite us, use proteins in our blood to reproduce—and repeat. Mosquitoes, as much as they feel like a seasonal nuisance in the Northeast US, are deadly creatures that kill more people than any other animal in the world. Depending where they live, certain types of mosquitoes transmit diseases like malaria, West Nile virus, Zika virus, dengue, eastern equine encephalitis, and others. And warmer, dry, and tropical climates battle mosquitoes all year long. 

Younger is working to crack the code on how mosquitoes use their sense of smell to track us in order to better understand how we can repel them more effectively. In a new paper published in Cell, Younger and her colleagues describe the unique and previously unknown way Aedes aegypti mosquitoes process smell at the biological level; their findings are a departure from the central theories that previously guided our understanding of insect olfaction. 

Aedes aegypti mosquitoes normally inhabit warm, tropical climates, and have caused minor outbreaks of dengue in southern states like Florida and Texas. But in recent years, they’ve been spotted as far north as Connecticut, raising alarm bells about what to expect as global temperatures continue to warm. 

“This is part of why this work is going to get more and more important,” says Younger, who began the study while completing postdoctoral research with Leslie B. Vosshall at The Rockefeller University, a biomedical research-focused institution in New York.

How Smell Works

For humans, scents are registered in the brain by a flow of communication that begins in the nose, which is lined with special cells called olfactory sensory neurons. These neurons—which house sensory receptors, specialized molecules that are stimulated by odor particles—act as detectors of odor and as messengers to the brain.

“The central dogma in olfaction is that sensory neurons, for us in our nose, each express one type of olfactory receptor,” Younger says. This is the underlying organizational principle of olfaction: one receptor to one neuron. For example, the smell of a freshly baked apple pie is actually a chemical code created by different odor molecules. As the distinct smell wafts into our noses, it triggers sensory receptors that match the different odor molecules; corresponding neurons then communicate to a brain region called the olfactory bulb—or the antenna lobe in insects—where it maps the odor code.

According to the study findings, Aedes aegypti mosquitoes’ olfactory system is organized very differently, with multiple sensory receptors housed within one neuron, a process called gene coexpression. This uniquely specialized olfactory system could help explain why mosquitoes are so good at sniffing out humans to bite. 

“This is shockingly weird,” says Younger, who initially thought her look into mosquito sensory neurons would prove it to be like every other olfactory system, like in flies and mice. The difference might seem technical, but it suggests that mosquitoes’ sense of smell is highly attuned to humans. “It’s not what we expected,” she says.   

Past research has found that even eliminating entire receptors in mosquitoes that are used for decoding carbon dioxide—a major chemical cue that they use to hunt humans—does not interfere with them finding people. Younger’s latest study may indicate one reason why.

In her lab at BU, Younger is raising mosquitoes in incubators and using modern genetic tools to understand olfaction in ways that were not possible a decade ago. For this study, the researchers developed mosquitoes that would light up under the microscope when exposed to certain smells—they expressed fluorescent proteins that glow under the microscope, allowing the researchers to see chemical responses to odorants. They also used CRISPR technology (which stands for clustered regularly interspaced short palindromic repeats and is a genetic tool created to edit DNA in living organisms) to label different groups of sensory neurons, while preserving the function of the cell proteins.

All of the results point to an olfactory system that is unconventional in the way that it coexpresses sensory receptors within individual sensory neurons. This suggests redundancy in the code for human odor—and possibly a stronger sense of smell that draws mosquitoes to humans. The next step is figuring out what role coexpression plays in driving the behaviors of Aedes aegypti mosquitoes. 

“A compelling idea is that it’s making them good at finding people,” Younger says. Her long-term goal is to intervene in mosquito biting by generating new, improved repellents, or attractants that are more appealing to mosquitoes than human blood. “As we learn about how odor is encoded in their olfactory system, we can create compounds that are more effective based on their biology,” she says.  

Until then, Younger uses bug spray—brands with 15 to 25 percent DEET or picaridin tend to be rated most effective—to protect herself from mosquitoes outdoors. Eventually, with more and more research, she hopes there will be a better option. 

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JOURNAL

Cell

ARTICLE TITLE

Non-canonical odor coding in the mosquito