Category: Science

A substance typically extracted from a rare Chinese plant may offer an effective and environmentally friendly way to control rats on a large scale, according to a new study.

And because the product impedes the ability of rats to reproduce instead of killing them, it is humane.

Rats thrive wherever there are humans. They have colonized every continent except Antarctica. Destruction and disease comes in their wake. Yet our fight against them has proven both ineffective—partly due to resistance—and dangerous to ecosystems.

“I joke a bit about this being a ‘woke’ product. It is sustainable, ethical to animals, and even strong on gender equality, as male rats are also targeted by this contraception. They become infertile for about a month after consuming it, which causes rat populations to drop dramatically,” says Johan Andersen-Ranberg of the plant and environmental sciences department at the University of Copenhagen and a founder of TripBIO, a spinout company involved in the substance’s development.

Rats are lured to a sweet and sticky liquid from a feeder developed by SenesTech, an American company. Among the sweet rat treat’s active ingredients is triptolide, a substance that makes the liquid a kind of contraceptive stew for male and female rats alike.

The substance is derived from Tripterygium wilfordii, also known as Thunder god vine, a rare Chinese vine plant that is harvested in the mountains by local gatherers. According to Andersen-Ranberg, in addition to being difficult to find and unstable in delivery, the plant also produces very little of the active substance. So little, that its value by weight is fifteen times more than gold.

As reported in Nature Communications, the researchers have found the enzymes and genes in the plant responsible for the substance, decoded the relevant DNA, and encoded it in the genetic material of a yeast. By doing so, they can ferment and produce the substance in a much faster, more stable, and, not least, cheaper way.

Dangerous rats, dangerous remedies

Extremely potent poisons are now used for rat control. But rats are cunning critters. If a poison encountered by a rat is not strong enough to kill it, the rodent will quickly find out how to avoid human traps. Furthermore, in Denmark among other places, many rats have developed resistance to milder poison variants.

The powerful poisons damage ecosystems and degrade very slowly, often taking a year before their effect is halved. During this time, birds and any scavengers that eat the rats can also receive lethal doses and carry the poison with them into the wild.

The authorities are aware of these “extremely toxic” current remedies, as the Danish Environmental Protection Agency refers to them, but allow them for a lack of alternatives and because the danger posed by rats is considered to be greater.

While nearly seven hundred years have passed since the Black Death here in Europe, as carriers of disease, rats are still considered a threat to public health. Elsewhere in the world, the problem is much greater. They are also responsible for significant economic damage. Their burrowing can damage sewer lines and even cause a home’s foundation to shift, making them a source of expensive to repair damages.

Environmental, ethical solution

The yeast developed by the researchers can be scaled to produce enough triptolide that even a problem as global and pervasive as rat control can realistically be solved with TriptoBIO as a supplier of this valuable substance.

“With our research and the yeast, we’ve now developed, we can ensure supply and get the price of triptolide down to a level where it is realistic for this environmentally friendly and ethical alternative to existing rat control to be widely used, Andersen-Ranberg says. “We are starting in the US, but are optimistic about getting the rest of the world on board.

“Initially, we will probably only make a few kilos of the substance. But when rat control using our substance grows as large as demand leaves us to believe that it will, we will be producing it by the ton. And we’ll be ready. On top of that, there are plenty of other perspectives for this substance. A number of other projects are also under development in which triptolide is a necessary ingredient. Fortunately, we can easily scale up.”

Source: Kristian Bjørn-Hansen for University of Copenhagen

Asking young people to take a short survey on a tablet before an appointment may help mental health providers identify those at risk of psychosis, according to new research.

The researchers found that when patients took a 21-question pre-visit survey, more than twice as many were identified at risk of psychosis compared to those who did not complete the survey.

But despite the improvement in detecting people at risk, the technology-based screening did not reduce the time between the participants’ first psychotic symptoms and when they received treatment.

Previous studies have shown that the longer the time between the first psychotic incident—such as hallucinations or delusions—and receiving treatment, the more severe the course of the disease.

According to the National Institute of Mental Health, psychosis often begins when a person is in his or her late teens to mid-twenties. About 100,000 new cases of psychosis are diagnosed each year in the US.

“The addition of a brief screener at the initial evaluation can make a dramatic difference in clinical decision-making, helping you to realize that an individual needs specialized care,” says Tara A. Niendam, a professor and executive director of the Health Early Psychosis Programs at the University of California, Davis, and first author of the study in JAMA Psychiatry.

Delayed mental health access in US

The researchers used data from 10 community clinics and four school sites in California. Sites were divided by those that used tablets for screening (“active screening”) and those that screened using clinical judgment (“treatment as usual”).

For the sites with active screening, individuals between the ages of 12 and 30 completed a questionnaire on a tablet before their visit with a mental health care provider.

Known as the PQ-B (Prodromal Questionnaire, Brief Version), questions included “Do familiar surroundings sometimes seem strange, confusing, threatening, or unreal to you?” and “Have you seen things that other people can’t see or don’t seem to see?”

If the questionnaire score was 20 or above, the participant was offered a referral to an early psychosis clinic for further evaluation.

If you or a loved one think you may be experiencing psychosis symptoms, UC Davis Health offers a free online screening survey.

Sites not using active screening relied on clinical judgment for further evaluation and referrals to early psychosis clinics.

The researchers evaluated data from 2,432 individuals at the active-screening sites and 2,455 at the treatment-as-usual sites.

Active-screening sites reported a significantly higher detection rate of psychosis spectrum disorders, with 136 cases (5.6%), compared to 65 (2.6%) in the sites that did not use the tablet screening.

The active-screening sites also referred 13 individuals with first-episode psychosis compared to four in the sites that did not use active screening.

But despite the early detection, the data showed no statistically significant difference in the duration of untreated psychosis. The mean for the active screening group was 239 days. The mean was 262.3 for the treatment-as-usual group.

The researchers note this was likely due to multiple factors leading to delayed access to the mental health system in the US.

“On average, our participants experienced untreated psychosis for approximately six months before presenting at one of our participating clinic sites,” says coauthor Mark Savill, assistant professor in the psychiatry and behavioral sciences department.

“A multifaceted approach that focuses on supporting individuals to seek help quicker and improving the pathway to appropriate services once they present for care may be necessary to achieve meaningful reductions in the duration of untreated psychosis.”

Benefits of psychosis screening

Twenty-four sites agreed to participate. However, only 10 community clinics and four school sites were able to fully implement the screening. Some study sites, such as primary care clinics, faced challenges implementing the screenings and reporting feedback; schools struggled with staffing issues and parent engagement.

The setbacks highlight some of the challenges that might be faced scaling up programs that offer the active screening. But the results highlight how many young people at risk of psychosis are not being identified with the current system.

“Population-based screening for psychosis has not been addressed systematically in the US prior to this study,” says senior author Cameron S. Carter, a professor of psychiatry and psychology and director of the UC Davis Health Imaging Research Center and the Behavioral Health Center for Excellence.

“Our increased identification of cases using the PQ-B questionnaire is an important finding. More people in this active group are getting into care,” Carter says. “That’s important because we know from previous research that individuals who are identified and receive treatment at the very early stages in their illness are likely to have the best outcomes.”

Additional coauthors are from the University of California, San Francisco; the University of Maryland, Baltimore; and UC Davis.

The National Institute of Mental Health funded the work.

Source: UC Davis

Deaths during pregnancy and the first year postpartum increased by 35% in the first nine months of the pandemic compared to the prior year, according to a new study.

The research found that deaths due to drugs, homicides, obstetric causes, and motor vehicle accidents all increased by 25%-55% during that period.

Only pregnancy-associated suicides declined during 2019-20, says study lead author Claire Margerison, an associate professor of epidemiology and biostatistics in the Michigan State University College of Human Medicine.

“We suspect these deaths are just the tip of the iceberg in terms of morbidity and suffering due to mental health, intimate partner violence, and substance use during pregnancy and postpartum,” says Margerison, a population health scientist in the epidemiology and biostatistics department. “These causes of death have been increasing over time, but it appears the pandemic exacerbated the ongoing upward trend in these deaths.”

For the study, published in JAMA Network Open, the researchers looked at death certificate records between 2018-20 of female US residents ages 15 to 44. The certificates have a standardized pregnancy box asking whether the decedent was pregnant at the time of death, within 42 days of death, or between 43 days and one year of death. All three categories were included as pregnancy-associated deaths. After calculating the pregnancy-associated death ratio, which previous studies had looked at, the researchers also looked at causes of death.

According to the report, the overall pregnancy-associated death ratio in 2020 was 66.9 deaths per 100,000 live births, an increase of 35% from the previous year. In that period, deaths due to drugs increased 55%; homicides by 41%; obstetric causes by 28%, and other causes (primarily motor vehicle accidents) by nearly 57%.

“Pregnancy is considered a window of opportunity for screening and prevention related to physical, mental, and behavioral health,” Margerison says. “Our data suggest that such opportunities were missed for hundreds of families during the pandemic.

“There is a critical need for prevention and intervention efforts—including harm reduction strategies—tailored to pregnant and postpartum people, particularly during times of population stress and decreased utilization of preventive care, such as a pandemic.”

Margerison says the study adds to the growing literature showing the impact the pandemic had on pregnancy-associated deaths, and that the team is planning on looking at other demographic patterns such as location and race/ethnicity to see how the pandemic affected different populations.

“We know that there are substantial and persistent inequities in these deaths by race and ethnicity,” Margerison says, adding they also are looking to better understand the pandemic’s impact on pregnant people.

“We’re looking at other data sets to understand how many people are going into emergency departments for similar issues or how many people are getting care in an outpatient setting. We want to understand the magnitude of the iceberg underneath the surface,” she says.

Additional coauthors are from Michigan State; the University of California, Merced; and Johns Hopkins University.

Source: Michigan State

A new way to measure the length of a single telomere could provide information on how rapidly we are aging and what we need to do to slow it down.

Telomeres—the caps at the ends of chromosomes that protect our genetic materials from the brunt of cellular wear and tear—are known to shorten and fray over time. Lifestyle, diet, and stress can exacerbate this process, leading to early loss of telomere protection and increasing the chances of early aging and lifestyle diseases, such as cancer and heart diseases.

To date, approaches for measuring biological aging based on telomere length have been limited as they can only ascertain average telomere lengths within a pool of DNA fragments, or are time-consuming and require highly-skilled specialists.

Being able to accurately and efficiently measure the length of an individual’s telomeres could open the doors to developing lifestyle interventions that slow aging and prevent disease.

“We applied a novel approach that uses DNA sequences—we call them ‘telobaits’—to latch onto the ends of telomeres in large pools of DNA fragments, like fishing in pond. Then, with specific scissor-like enzymes, we snip the telomeres out of the pools,” says Li Shang, associate professor with the Duke-NUS Cancer & Stem Cell Biology Programme and senior author of the study in Nature Communications.

“Using high-throughput genetic sequencing technology, we were able to read the DNA ‘letters’ that comprised each individual telomere, allowing us to very precisely measure their lengths.”

The team successfully validated this approach when they tested it using human cell lines and patient cells. Interestingly, the sequencing results revealed that the genetic sequences within certain parts of the telomeres, known as telomeric variant sequences, were distinct to each individual person.

“Based on this insight, a future area of study for us is the possible use of telomeric variant sequences as a means of biological identification, which could potentially prove useful for expanding the field of forensic science,” Li says.

The team believes this new approach could be used as a predictive biomarker for human aging and disease at the individual level, as well as for population-level studies on the impacts of lifestyle, diet, and the environment on human health.

“This method for telomere length measurement is an important advance in the field of aging research,” says senior coauthor Angela Koh, associate professor who is senior consultant with the department of cardiology at NHCS and associate professor with the SingHealth Duke-NUS Cardiovascular Sciences Academic Clinical Programme.

“From the clinical perspective, we view this as a very promising method for understanding clinical diseases associated with aging such as cardiovascular disease. Our partnership signifies what can be achieved by clinician-and-biomedical scientists to bring complex lab methods towards simpler, quantifiable methods that may be used in broader clinical labs in the future.”

Additional coauthors are from the Cancer Science Institute of Singapore; the National University of Singapore; A*STAR’s Genome Institute of Singapore and Institute of Molecular and Cell Biology; National Cancer Centre Singapore; Singapore General Hospital; the SingHealth Duke-NUS Institute of Precision Medicine; Kumamoto University (Japan); Guangzhou Medical University (China); the Chinese University of Hong Kong-Shenzhen (China); Shanghai University (China); and the University of California, Davis.

Source: Duke-NUS

Climate change and the projected savannization of the Brazilian Amazon threaten most land-based mammals that live there, new research shows.

“We’re losing Amazon forest as we speak.”

Threatened animals include jaguars, ocelots, anteaters, and capybara, but also animals that use both forest and savanna habitats, such as pumas and giant armadillos.

The study in the journal Animal Conservation also illustrates how species and lands protected through local conservation efforts are not immune to global climate change.

“We’re losing Amazon forest as we speak,” says lead author Daniel Rocha, who conducted the research as a doctoral student in the department of wildlife, fish, and conservation biology department at the University of California, Davis.

“The Amazon’s biodiversity is very susceptible to climate change effects. It’s not just local; it’s a global phenomenon. We cannot stop this just by law enforcement, for example. These species are more susceptible than we realized, and even protected areas can’t protect them as much as we thought.”

‘Savannization’ in the Brazilian Amazon

Pristine savanna is a unique biome that supports a diverse array of life. But “savannization” here refers to when lush rainforest gives way to a drier, open landscape that resembles savanna but is actually degraded forest. Local deforestation and global climate changes in temperature and precipitation favor this conversion along the southern and eastern edges of the Brazilian Amazon.

Arboreal species like monkeys clearly will be affected by such changes. But the study’s authors wanted to better understand how land-based mammals are expected to fare—especially those who use both forest and savanna habitats when they have access to both.

“Unfortunately, there are more losers than winners.”

The researchers conducted camera trap surveys of land-based mammals in four protected areas of the southern Brazilian Amazon, which is a mixture of rainforest and natural Cerrado, or savanna. Using statistical models, they quantified how savanna habitat affected 31 species. They then looked for differences among species known to use mostly rainforest, savanna, or both habitats.

The results showed that only a few species preferred savanna habitat. Rocha notes that the models were based on pristine—not degraded—savanna, so the negative effects of savannization among animals will likely be even stronger.

Riparian forests, which line the wet edges of rivers and streams, helped buffer the effects of savannization to some extent.

Rainforest winners and losers

“Unfortunately, there are more losers than winners,” says Rocha, who is currently an assistant professor at Southern Nazarene University in Oklahoma. “Most Amazon species, when they can choose between good forests and good savanna, they choose the forest. That’s true even for species considered ‘generalists,’ which use both habitats. As we lose forests, they suffer, too.”

The results indicate that if climate-driven savannization causes species to lose access to their preferred habitat, it will reduce the ability of even protected areas to safeguard wildlife. The authors say that should be considered when assessing the potential climate-change effects on these species.

Rahel Sollmann, Rocha’s former advisor at UC Davis who is now at the Leibniz Institute for Zoo and Wildlife Research in Berlin, Germany, is a coauthor of the study.

The CAPES-Ministry of Education in Brazil, the National Geographic Society, Horodas Family Foundation for Conservation Research, the Explorers Club, Alongside Wildlife Foundation, and the Hellman Foundation funded the work. This study received logistical support from ICMBio.

Source: UC Davis

Mothers struggling with depression tend to take longer to respond to their child during back-and-forth dialogue, according to a new study.

The findings provide the basis for further research to determine if the slower response time has any long-term effects on the children’s language development, vocabulary, or academic outcomes.

For the study, published in the journal Infant and Child Development, researchers listened to audio recordings of more than 100 families who were involved in the Early Head Start program, a federal child development program for children whose family’s income is at or below the federal poverty line.

Some of the moms involved were struggling with depression, and the researchers documented how much time passed in between responses for a mother and her child during back-and-forth dialogue.

“We found that the time gap in between responses, in general, gets shorter between mother and child as the child ages, and we also found the mom’s timing tended to predict the child’s timing and vice versa,” says Nicholas Smith, an assistant professor in the School of Health Professions at the University of Missouri.

“Mothers and children are in sync. Children who were slower to respond to their mom often had moms who were slower to respond to the child, and children who were faster to respond to their mom had moms who were faster to respond to the child. The significant new finding was that the moms who were more depressed took longer to respond to their child compared to moms who were less depressed.”

In the longitudinal study, using audio recordings, researchers compared the response time of back-and-forth dialogue between mothers and their children when the children were 14 months old and 36 months old.

Going forward, Smith plans to further study the dialogue response timing for the same individuals that were recorded in this study when the children were in pre-kindergarten and also when they were in fifth grade to examine how these effects play out later on in the children’s development.

“The overall objective we are hoping to accomplish is to better understand how mother-child interaction works as well as the underlying mechanisms and potential factors at play,” Smith says.

“Once we identify what factors drive successful development outcomes and what factors potentially impair development, we can better identify at-risk children and then tailor potential interventions toward those that can benefit from them the most.”

The Mizzou Alumni Association funded the work.

Source: University of Missouri

A new method allows researchers to control and follow in real time how tau protein changes from a benign protein essential for normal function in our brains to the toxic tangles that are a signature of Alzheimer’s.

The technique uses low voltage electricity as a surrogate for the natural signals that trigger the protein to fold and assemble, both for its normal function in the brain and in the runaway process leading to often fatal disease.

“This method provides scientists a new means to trigger and simultaneously observe the dynamic changes in the protein as it transitions from good to bad,” says Daniel E. Morse, professor emeritus of biochemistry and molecular genetics at the University of California, Santa Barbara and senior author of the study in the Journal of Biological Chemistry.

“The method should be widely useful to identify molecules and conditions that direct different trajectories of assembly in a number of different but related amyloid diseases,” says lead author Eloise Masqulier.

Under normal circumstances, tau is a soluble protein that starts out in an open, loose configuration, like a piece of string. In response to a signal, tau proteins fold up and progressively assemble with one another, enabling them to bind to tiny cylindrical structures—microtubules—that support the shape of the neurons and transport nutrients and molecules inside the cells.

However, in pathological cases, the signal goes too far, causing the protein to assemble uncontrollably, forming the insoluble amyloid filaments that become neurofibrillary tangles inside neurons, interrupting their function and eventually killing them.

Using their new method with the core portion (a peptide) of tau, the investigators were able to observe and analyze a critical “tipping point” between normal, reversible folding and assembly, and the irreversible, pathological assembly that underlies tauopathic, neurodegenerative diseases.

Using less than a volt of electrical potential to mimic hyperphosphorylation (the disease-promoting signal), the scientists triggered and finely tuned the tau-peptide’s folding in their lab experiments, using spectroscopic methods to reveal details of the folding and progressive assembly to form amyloid-like filaments.

Unlike other modes of examining protein folding and assembly, such as X-ray diffraction or cryo-electron microscopy that provide static snapshots of the processes as they occur in time, the new electrochemical method allows users to continuously witness and analyze details of the progressive, dynamical folding and assembly as they occur in real time, permitting the first direct observations of the critical earliest steps in these processes.

Also, unlike most techniques previously used for studies of tau and its core peptide, because the electrical trigger closely mimics the natural triggering signal, the method permits direct observation of these processes without the need for additional “helper” molecules.

The authors report that the technology can also be used as a tool to more rapidly test and identify drugs and antibodies potentially useful for prevention or treatment of Alzheimer’s and other amyloid diseases.

“Because we can turn on and fine-tune the process at will,” Morse says, “we can use this system to see what molecules could interdict or block specific stages of folding and assembly.”

Source: UC Santa Barbara

The cannabis component CBD inhibits the breakdown of THC, which may result in a stronger and longer high after using edibles, research finds.

Contrary to some common claims, the researchers found that relatively high doses of CBD may increase the adverse effects of THC, the main active ingredient in cannabis that can cause a mood alteration or a “high” sensation.

The results of the study, published in JAMA Network Open, show that the maximum amount of THC measured in participants’ blood samples was almost twice as high after consuming a brownie containing THC with CBD than after eating a brownie with only THC, even though the dose of THC in each brownie (20 mg) was the same. In addition, the maximum amount of 11-OH-THC (a metabolic byproduct of THC that produces drug effects similar to THC) was 10-fold greater after eating the brownie with the high CBD extract compared with the one containing high THC extract.

The work examines how the body absorbs, eliminates, and responds to cannabis extracts that varied with respect to THC and CBD concentrations.

“The fact that THC and CBD were orally administered was very important for the study and played a large role in the behavioral effects and drug interactions we saw,” says Austin Zamarripa, postdoctoral research fellow at the Johns Hopkins University School of Medicine and the study’s lead author.

Prior controlled human studies evaluating these interactions have predominantly administered THC and CBD by inhalation or intravenously, or have not administered them at the same time. For this reason, much of the existing data regarding interactions between THC and CBD may not apply to edible cannabis products such as baked goods, candies, and gummies, which get metabolized in the intestine and liver.

“Overall, we saw stronger subjective drug effects, greater impairment of cognitive [thinking] and psychomotor [moving] ability and greater increase in heart rate when the same dose of THC was given in a high CBD cannabis extract, compared with a high THC extract with no CBD,” says Zamarripa.

The new study, which tested each type of cannabis extract and a placebo within the same subjects rather than using different people for each drug type, took place from January 2021 to March 2022 at the Behavioral Pharmacology Research Unit at Johns Hopkins Bayview Medical Center. The researchers recruited 18 adult participants (11 men and 7 women) who had not used cannabis for at least 30 days prior to beginning the study.

Study volunteers took part in three sessions, each separated by at least one week. In each session, participants consumed a brownie containing either 20 mg of THC, 20 mg of THC and 640 mg of CBD, or no THC or CBD (placebo). Neither the participants nor the investigators knew in advance what was in the brownie that participants ate on a given session. Participants also took a drug cocktail consisting of five cytochrome, or CYP, probe drugs (100 mg caffeine, 25 mg losartan, 20 mg omeprazole, 30 mg dextromethorphan, and 2 mg midazolam) 30 minutes after eating each brownie. These drugs will help the scientists figure out how CBD and THC affect how participants’ bodies metabolize other commonly used medications and dietary supplements (in analyses that they will publish separately).

To create a basis for comparison, baseline blood samples were collected from all participants before each session, along with their vital signs, including heart rate and blood pressure, and measures of cognitive and psychomotor performance. Participants provided blood and urine samples at timed intervals for 12 hours and then again approximately 24 hours after drug dosing was completed. Self-reported drug effects were measured using the Drug Effect Questionnaire, or DEQ, a standardized tool used to assess aspects of subjective experiences after being given a psychoactive drug like THC or cannabis.

Although participants experienced the typical effects produced by cannabis with both the CBD and THC extracts, there were notable differences between the two, which are likely the result of the increased concentration of THC and 11-OH-THC in the blood after the CBD extract was consumed.

Using the DEQ tool, participants rated subjective drug effects with a scale from 0 to 100, with 0 being “not at all affected” and 100 being “extremely affected.” Among the subjective ratings, participants experienced greater increases in overall drug effects, unpleasant drug effects, feeling sick, dry/red eyes, and difficulty performing routine tasks when they consumed the brownie with both CBD and THC compared the THC-only brownie. After eating the brownie with the high CBD cannabis extract, participants showed significantly more impairment in performance on tests of memory and attention compared with when they consumed the brownie with the high THC extract.

Consuming the high CBD extract brownie also resulted in a greater increase in heart rate, from a 10 beats per minute increase from baseline [THC] to a 25 beats per minute increase from baseline [THC + CBD]. The placebo brownie did not increase the subjective drug effect ratings or alter the performance on any cognitive or psychomotor tasks.

“We have demonstrated that with a relatively high oral dose of CBD [640 mg] there can be significant metabolic interactions between THC and CBD, such that the THC effects are stronger, longer-lasting, and tend to reflect an increase in unwanted adverse effects,” says Ryan Vandrey, professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine and the study’s senior author.

Vandrey notes that another of his team’s recent studies found that CBD products don’t always have correct labels.

“Our new study suggests that it’s important for folks to be aware that if they’re going to take a high-dose CBD extract, they also need to be mindful about interactions with other medications. Individuals should discuss with their doctor whether they should consider dose adjustments of THC and other medications if they’re also taking CBD,” says Vandrey.

The researchers say that future studies are needed to further understand the impact of CBD and THC dose, relative concentration, frequency of use, and individual health differences on how our bodies metabolize commonly used medications. This kind of research is needed to inform clinical and regulatory decision-making regarding the therapeutic and nontherapeutic use of cannabis products.

Source: Johns Hopkins University

A newly identified tsetse fly pheromone reveals new insights into how the insects communicate—and may help in reducing disease spread.

The tsetse fly is a blood-sucking insect that spreads diseases in both humans and animals across much of sub-Saharan Africa.

Tsetse flies are known to carry parasites called African trypanosomes. When the insects bite humans or animals, they transmit these parasites, spreading diseases such as African sleeping sickness, which can be fatal to humans, and nagana, a disease that affects livestock and other animals.

“African sleeping sickness is a dreadful disease that’s hard to treat. Our immune systems have a hard time clearing trypanosomes and most of the drugs we have to kill them are toxic,” says John Carlson, professor of molecular, cellular, and developmental biology at Yale University and senior author of the new study. “And nagana, which affects livestock, has had terrible economic impacts in the region.”

Further, with climate change projected to expand the areas in which tsetse flies can survive, more humans and animals are expected to be affected by these diseases in the coming years.

One strategy identified as a way to control the spread of tsetse flies is to use their own pheromones—particularly volatile pheromones, or pheromones that work over distances rather than through direct contact—to attract and trap the insects.

To identify volatile pheromones that might be used for this purpose, the researchers took tsetse flies—of the species G. morsitans—and placed them in a liquid to collect any chemicals they might be emitting. They then ran those extracts through a device called a gas chromatograph-mass spectrometer, which can identify specific compounds from a mixed sample.

The researchers found several chemicals that had never previously been reported, including three that elicited responses from tsetse flies. One in particular, a chemical called methyl palmitoleate (MPO), had the strongest effects.

Specifically, in a series of experiments led by first author Shimaa Ebrahim, a postdoctoral fellow in Carlson’s lab, researchers found that MPO attracted male tsetse flies, caused them to stop and remain where they were for some time, and acted as an aphrodisiac. A drop of liquid containing MPO attracted male tsetse flies to knots in yarn that only resembled flies and to females of another tsetse fly species that they would not typically interact with.

To better understand how MPO mediated behavior, the researchers then tested whether neurons on the flies’ antennae responded to MPO. Indeed, they identified a subpopulation of olfactory neurons on the antennae that increased their firing rates when exposed to the pheromone.

Together, the findings indicate that MPO is a tsetse fly attractant, say the researchers, and therefore, it may be useful in slowing disease spread.

Currently, the most effective method of controlling tsetse fly populations is through traps that use odors from the animals the flies prefer to feed on.

“Now we’ve found this pheromone that could be used in combination with the host odors,” says Carlson. “Especially since MPO not only attracts the flies but causes them to freeze where they are.”

While animal odors have the benefit of attracting tsetse flies across large distances, they tend to fade quickly. MPO works at shorter distances but is effective for longer periods of time, Carlson adds.

“MPO could be one more tool in the toolbox when it comes to combatting tsetse flies and the diseases they spread,” he says.

The team is now working with collaborators in Kenya to test whether MPO is useful in traps in the real world, not just in a lab setting.

Additionally, the researchers want to understand what causes tsetse flies infected with trypanosomes to emit an entirely different set of chemicals—something else they identified in the study—and how that affects fly communication.

The study appears in the journal Science.

Source: Mallory Locklear for Yale University