Research

What rats can tell us about the opioid crisis

Rachel Sauer — Mon, 14 Jul 2025 13:30:00 +0000

What rats can tell us about the opioid crisis Rachel Sauer Mon, 07/14/2025 - 07:30

Blake Puscher

CU Boulder scientists estimate the heritability of opioid use disorder with a rodent study

Opioid use disorder is an ongoing global health crisis. In the United States alone, almost 108,000 people died from drug overdose in 2022, and about 75% of those deaths involved opioids.

Although many factors contribute to this crisis—and there are many approaches to addressing it as a result—one important line of research is into the genetic factors that increase people’s risk for developing an opioid use disorder (OUD). Once these risk factors are known, doctors may be able to prescribe opioids more strategically to people at higher risk of OUD, and such individuals could make more informed choices.

In recently published research, scientists from the ��—including Eamonn Duffy, Jack Ward, Luanne Hale, Kyle Brown and Ryan Bachtell of the Bachtell Laboratory, and Andrew Kwilasz, Erika Mehrhoff, Laura Saba and Marissa Ehringer—tested the influence of genetics on opioid-related behaviors, which include OUD. Specifically, they looked at its heritability by conducting an experiment in which rats were given the ability to self-administer oxycodone, a semi-synthetic opioid that is used medically to treat pain.

CU Boulder researchers tested the influence of genetics on opioid-related behaviors, specifically looking at its heritability by conducting an experiment in which rats were given the ability to self-administer oxycodone, a semi-synthetic opioid that is used medically to treat pain. (Photo: Jon Anders Wiken/Dreamstime.com)

Experimental design

More than 260 inbred rats from 15 strains were used for the study. In this case, an inbred strain is defined as a population produced by 20 or more generations of brother-sister mating. This was important for the study because the rats within inbred strain are isogenic: “They’re almost like clones; their genomes are identical, except for the X and Y chromosomes between males and females,” Duffy explains.

Like the use of identical-twin research involving humans, this makes the results more reliable. In a twin study, most differences between twins are caused by their environment, so researchers can determine the genetic influence on a trait by how much it varies. Similarly, within an inbred strain, most individual differences are caused by sex differences, and this provides insight into the importance of biological sex to a given trait. Between inbred strains, differences are attributable to either the strains’ different genes, sex differences, or a combination of the two.

The animals in the study could self-administer the oxycodone using levers, so their behaviors could be measured. There were two retractable levers in the testing chamber: one active, which would give the rats a dose of oxycodone after being pulled, and one inactive, which would do nothing.

After the active lever was pulled, there was a cooldown period of 20 seconds, during which time pulling the lever would not dispense another dose. Regardless of whether pulling a lever had an effect, it would be recorded. This allowed researchers to measure two substance-use behaviors in addition to the total amount of oxycodone consumed. These variables were referred to as “timeout responding” and “lever discrimination.”

Timeout responses were pulls on the active lever that happened during the cooldown period. Lever discrimination was a measure of how often rats pulled the inactive lever. Both essentially tracked the rats’ ability to self-administer substances in a regulated manner, although lever discrimination could have other associations. Attempting to get more oxycodone very quickly (timeout responding) and attempting to get it in an illogical way (low lever discrimination, especially once the animals had time to learn how the levers worked) are signs of dysregulated drug use.

These measures are important in addition to total dosage because the rats naturally consumed more oxycodone as they developed a tolerance to the drug, making it difficult to characterize their drug use on that basis alone. “With addiction,” Duffy says, “it’s a complicated story. They’re developing tolerance, and they’re showing dysregulated use.”

Push the lever, get the oxycodone

The tests were split into two phases: acquisition and escalation. Although the number of daily doses the rats received generally increased over time, especially between the two phases, their self-administration behaviors varied significantly by strain.

For example, in the escalation phase, the females of one strain pushed the lever for a total oxycodone dose of less than 100 mg/kg, whereas rats of another strain took a total of about 300. There was also variation between males and females within a strain, though not always: In some strains, males and females consumed a similar amount of oxycodone, while in others, consumption was notably divergent, with males consuming around 200 mg/kg more oxycodone overall.

Once the genetic factors that increase people's risk for developing an opioid use disorder (OUD) are known, doctors may be able to prescribe opioids more strategically to people at higher risk of OUD, and such individuals could make more informed choices. (Photo illustration: iStock)

This is evidence for a strain-sex interaction, meaning that the rats’ substance-use behaviors were determined by a combination of genetic background and biological sex, not either alone, according to the researchers. Although the obvious explanation for this would be different genes encoded on the sex chromosomes of the various strains, this isn’t necessarily the case.

“Some of our collaborators in San Diego have performed several genetic mapping studies,” Duffy says, “and they found that the Y chromosome didn’t appear to play much of a role in regulating behavioral traits.”

It is possible that X-chromosome genes are a greater factor. However, the biggest influence would probably be sex hormones or related differences, Duffy adds. For example, according a separate study, the sex hormone estradiol can increase oxycodone metabolism indirectly by raising the concentration of a protein in the brain.

Moreover, Duffy says, “there could be developmental aspects to the sex difference, so seeing if they’re exposed to testosterone versus estrogen as they’re growing up, that may affect how their brain is wired.”

Several other strains showed notably divergent behaviors. Some strains were fairly stable in their use, while others increased their oxycodone intake rapidly during the acquisition phase. Lever discrimination also varied by strain, with one strain increasing its lever discrimination quickly, for example, while another failed to increase its lever discrimination much over time.

The biggest discovery that emerged from the research was the discovery of how heritable several behaviors related to opioid use are.

The influence of genetics

Heritability is a measure of what part of the variation in a group is due to genetic or heritable characteristics.

“With heritability,” Duffy explains, “when you’re looking at everything that goes into some kind of trait, like opioid use disorder, the average genetic component will be your heritability. You also have environmental influences, which could be things such as diet.”

Taking OUC as an example, variation might be understood qualitatively in terms of how destructive the effects of drug use are on individuals, from having minimal effect on people’s lives to potentially causing overdoses and death, Duffy adds.

If the heritability of OUD were 0, the fact that some people use the drug safely and others die because of it would be explained entirely by non-genetic factors. If the heritability of OUD were 1, this fact would be explained entirely by genetics. However, as with most traits, OUD appears to be caused by a combination of genetic and environmental factors.

According to the study, measures of oxycodone intake ranged between 0.26 and 0.54 heritability. The high end of this range is total oxycodone intake over the course of the experiment, while the low end is change in intake (increase in intake over the acquisition phase). The other behavioral phenotypes had heritability scores of 0.25 to 0.42, with timeout responding being more heritable than lever discrimination.

“�� half of that variability is due to genetic background,” Duffy says, referring to total intake. “That’s really strong heritability.” However, because these data come from rats, the heritability of these behavioral phenotypes may be different in humans. “We’re not going to capture everything about OUD in a rat model, but we can capture specific aspects and use that to put together a bigger picture.

“OUD is hard to study in humans because there aren’t as many people using opioids as alcohol or nicotine, and of that smaller population, we also have people using several types of drugs, so it’s harder to calculate these heritability values, but I believe ours do fall within the range for opioid dependence and opioid use disorder in humans.”

“With addiction, it’s a complicated story. They’re developing tolerance, and they’re showing dysregulated use.”

It's also important to recognize that heritability is a population-level statistic. This means that it does not represent the chance for any individual to develop a trait, even if that trait could be inherited from the individual’s parents. However, a higher heritability of some trait would correspond to a greater resemblance between parents and offspring in that respect throughout the population, Duffy says.

What genes contribute to OUD?

While it is useful to know how heritable opioid use disorder is, meaningfully assessing the risk for individuals requires knowing what genes contribute to it. This study doesn’t identify these genes, but progress has already been made to this end.

“There’ve been a number of studies in humans that have found that these SNPs, or single nucleotide polymorphisms, are associated with your risk of developing conditions like opioid dependence or opioid use disorder,” Duffy says. “There’s another group that is performing some genetic mapping in outbred rats, and that’s going to be the next stage of this project for us as well.”

One potential gene influencing OUD in mice is an SNP in the Oprm1 gene, which is explained in the study to affect the brain’s response to reward-related behavior generally and analgesics like oxycodone specifically. Common Oprm1 SNPs have also been associated with dysregulated use of an opioid in humans, specifically heroin.

Once relevant SNPs are identified, however, the situation remains complex. “It’s not going to be a simple answer,” Duffy says. “Like, you have this one SNP in Oprm1 and that’s going to increase or influence your risk for OUD. It’s probably going to be a multitude of SNPs, and those additive effects are going to influence the risk for this disorder.”

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CU Boulder scientists estimate the heritability of opioid use disorder with a rodent study.

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How deep is that snow? Machine learning helps us know

Rachel Sauer — Thu, 10 Jul 2025 13:30:00 +0000

How deep is that snow? Machine learning helps us know Rachel Sauer Thu, 07/10/2025 - 07:30

Blake Puscher

CU Boulder researchers apply machine learning to snow hydrology in Colorado mountain drainage basins, finding a new way to accurately predict the availability of water

Determining how much water is contained as snow in mountain drainage basins is very important for water management, because measuring it is a necessary part of predicting the availability of water—especially in places that rely on snowmelt for their water supply, like Colorado and other western states.

Snow water equivalent is the amount of water in a mass of snow or snowpack. The depth of this water is a fraction of the snow depth, and this fraction is obtained by multiplying the depth by the snow density, which is expressed as a percentage of the density of water. If there are 10 inches of snow with a density of 10%, the snow water equivalent is 1 inch.

A persistent challenge is that snow water content is calculated from both snow depth and snow density, yet it remains unfeasible to directly measure snow density over a large area. Traditionally, this issue has been addressed with remote sensing, which allows for consistent and relatively large-scale measurements. However, remote sensing methods have their own limitations, which has prompted the search for an alternative in machine-learning technology.

CU Boulder researchers Jordan Herbert (left), a PhD candidate, and Eric Small, a professor of geological sciences, developed a model that can estimate the snow density at times when and in places where it has not been observed or sensed.

In their study on the subject, �� Ph.D. candidate Jordan Herbert and Professor Eric Small of the Department of Geological Sciences developed a model that can estimate the snow density at times when and in places where it has not been observed or sensed. This model is split into different scenarios, each trained on a different subset of the data, and while performance varied, all scenarios were more accurate than extrapolation from remote sensing methods, according to Herbert and Small.

Model performance analyses also demonstrated that information from Airborne light detection and ranging (LIDAR) can be transferred to different times and places within the region it was collected.

LIDAR and SNOTEL data

LIDAR surveys are an important tool in snow hydrology, as they provide detailed information about snow properties, specifically through their detection of snow depth.

“You fly the plane twice,” Small says, “once when there’s no snow, once when there is snow. The laser reflects off the surface, and if you know where the plane is and the distance to the surface, then you know the height of the snow relative to the ground surface.” This is called differential LIDAR altimetry.

While LIDAR is very useful in snow hydrology, it does have some limitations. The first is that it only measures snow depth, but snow density (either measured or modeled) is also needed to determine snow water equivalent. This isn’t a unique limitation, however, because snow density cannot be surveyed in the same way as snow depth.

“Measuring snow density in the field reveals just how variable the snowpack is,” Herbert explains. “Depending on if you dig a snow pit under a tree or on a north versus south facing aspect, you can get a completely different answer.”

This is a major limitation of on-site observations. Density also varies with depth, and remote sensing signals will be affected by the amount of liquid water content in snow, which makes measuring snow density remotely or over a broad scale impossible for the foreseeable future.

The second and more easily addressed issue with LIDAR surveys is the logistical issues associated with necessary plane flights.

“You can’t fly a plane all the time,” Small says. “It’s too expensive, and we don’t have enough planes to fly everywhere.” Planes also cannot be flown when the weather is bad, and surveys only provide a snapshot of snow depth, which can change rapidly as snow falls or melts.

“Measuring snow density in the field reveals just how variable the snowpack is. Depending on if you dig a snow pit under a tree or on a north versus south facing aspect, you can get a completely different answer,” says CU Boulder researcher Jordan Herbert. (Photo: Pixabay)

These limitations can be worked around by using the LIDAR data to train computer models. “Based on that,” Small says, “you can use the LIDAR information to make predictions in the absence of LIDAR at another time or date or location. So, you’re leveraging the scientific information from LIDAR to improve your knowledge generally.”

Snow telemetry (SNOTEL) is an automated system of snow and climate sensors run by the National Resource Conservation Service, which is part of the U.S. Department of Agriculture. There are about a thousand SNOTEL sites across the western United States—small wilderness areas filled with sensing equipment that measures precipitation, snow mass and snow depth.

“All snow hydrology is based on data from these stations,” Small says. “The problem is that they only cover a small area. If you take all the SNOTEL stations in the western U.S. and put them next to each other, they’d be about the size of a football field, so they’re vastly under sampling. That’s why people want to use LIDAR to fill in all the spaces around them.”

The random forest model

Linear regression makes quantitative predictions based on one or more variables, but it becomes difficult to perform when many of these variables interact with each other in complex ways. In this case, some examples are elevation, solar radiation, slope, tree cover and so on. The difficulty of working with all these variables can be minimized by a modeling tool called a regression tree.

“A binary regression tree splits your sample into two groups, and it splits that sample to figure out which variable has the most effect on the thing you're trying to predict,” Small explains. The branching structure created by these splits gives the model its name and is designed to minimize errors. Each branching point is a condition like true/false or yes/no, the answer to which determines the path taken.

Regression trees are useful in that they fit the data better than multiple linear regression models, which are the other option when it comes to using linear regression when there are many variables involved. The better a model fits the observed data, the better it will be at predicting data that have not been observed, Small says.

However, regression trees have their own limitations.

“The downside of a binary regression tree is that it only gives you categorized values,” Small says. “For example, snow depth could be 70 centimeters, 92 centimeters or 123 centimeters. You end up with a map that just has these particular values.” This issue can be solved by combining multiple regression trees into a random forest model.

“What a random forest does,” Small explains, “is take a bunch of these binary regression trees and samples them randomly to give you continuous distributions of the variable that you care about. So instead of it being in these categories, it's more like how we think about snow depth.”

“All snow hydrology is based on data from (SNOTEL) stations. The problem is that they only cover a small area. If you take all the SNOTEL stations in the western U.S. and put them next to each other, they’d be about the size of a football field, so they’re vastly under sampling," says CU Boulder Professor Eric Small. (Photo: Ruvin Miksanskiy/Pexels)

Machine learning

While using binary regression trees allows the predictive model discussed in this study to fit the data better, there are other things to consider, Small says. “In machine learning and other statistics, there’s this trade-off between how well a model can fit the information you give it and how generalizable it is. If I keep adding training data, training the model and tuning the parameters, I can have it fit the data pretty well, but then it becomes fixated on those very specific data, and it’s not going to make good predictions elsewhere.”

This is called “overfitting,” and it can be described simply as the model becoming too used to patterns in the data it was trained on. In anticipating these patterns, the model will make incorrect predictions that would have been right in the same place or under the same circumstances as the training data were collected, but aren’t otherwise.

This explains the different performance of the three different versions of the model: the site-specific model, the regional model and the site-specific and regional (SS+Reg) model. The site-specific model makes predictions about a given basin using LIDAR data from the same basin that was collected at other dates, whereas the regional model makes predictions about a basin using data from other basins and at other dates. The SS+Reg model was trained using all available data.

The SS+Reg model was the most accurate, but all models were generally accurate, both compared to models from prior studies and remote sensing methods. Because models of the sort used in this study output on the 50-meter scale, this scale was used to compare this study’s models to existing ones, and the former were more accurate. The models’ outputs were at a scale of 50 meters, but these were upscaled to 1- and 4-kilometer scales as well.

The 1- and 4-kilometer scales are more typically used in water management applications, and all three models became more accurate when applied to these scales, outperforming SNOTEL. This means that the models were more accurate than extrapolation from observation data. The success of both the SS+Reg and regional models indicates that information gained from LIDAR is transferable to different times and locations within the Rocky Mountain Region.

Besides fitting the data well and being adaptable to different scales between the three model scenarios, this approach is also beneficial because it does not rely on modeling physical processes (like snow formation, accumulation and melt) or on uncertain weather data. This makes it so that, once a model is trained, it doesn’t take long to make predictions. “The big gain is that it's much more computationally efficient and it just takes a fraction of the time,” Small says. “It's about 100 times faster.”

Herbert says “machine learning has been a huge benefit to my research, with the results to back it up. It’s freed up my time in the winter to put skis on and dig more snow pits to get the density data we desperately need.”

“For whatever reason, all our physically based models and our knowledge of science just gets in our way of making predictions,” Small explains, “because we've tried to boil it down to these simple equations, but it's not simple.”

"Machine learning has been a huge benefit to my research, with the results to back it up. It’s freed up my time in the winter to put skis on and dig more snow pits to get the density data we desperately need."

Expanding to other regions

The primary limitation of the snow density-measuring framework that the researchers created for this study was its reliance on on-site and LIDAR data for snow depth measurements. Small says that this could be addressed by bringing in other data sets, which would provide a more independent test of success than models’ ability to predict snow density in regions they were not trained on.

One of these data sets, the fractional snow-covered area (how much of the ground is covered by snow), could be measured using LIDAR equipment mounted to a satellite rather than relying on airplanes. While LIDAR has been used with satellite technology, this doesn’t address the limitations of plane-mounted LIDAR, because as Small says, “the (satellite) overpass interval is very slow. It’s about 90 days before it comes back to the place you’re looking at. So, you get a snapshot very infrequently, but it’s everywhere on the planet.”

The next step of developing this kind of model is to apply it to other regions, and it remains to be seen how easily that translation can be made, Herbert says.

“We’ve just begun running the model in California to see if the model works in regions with different climates,” he says. “We want to see how transferable data from one region is to another, and California is an ideal test site since it has more LIDAR than anywhere else in the world.”

The presence of LIDAR is important because these data were the most useful when it came to statistical model validation, or making sure that the models were accurate and reliable, compared to data limited by the small-area reporting of SNOTEL and the variability of on-the-ground snow density measurements. Without data to judge models’ predictions against, it is impossible to determine how well they do, because the actual snow depth is unknown.

Also, because LIDAR isn’t available everywhere, it is important to continue developing other methods of validation, the researchers say. Small says reducing reliance on LIDAR will help the innovative modeling framework apply to many parts of the country.

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CU Boulder researchers apply machine learning to snow hydrology in Colorado mountain drainage basins, finding a new way to accurately predict the availability of water.

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That lightbulb represents more than just a good idea

Rachel Sauer — Tue, 08 Jul 2025 18:39:18 +0000

That lightbulb represents more than just a good idea Rachel Sauer Tue, 07/08/2025 - 12:39

Rachel Sauer

In research recently published in Science, CU Boulder scientists detail how light—rather than energy-intensive heat—can efficiently and sustainably catalyze chemical transformations

For many people, the role that manufactured chemicals plays in their lives—whether they’re aware of it or not—may begin first thing in the morning. That paint on the bedroom walls? It contains manufactured chemicals.

From there, manufactured chemicals may show up in prescription medicine, in the bowls containing breakfast, in the key fob that unlocks the car, in the road they take to work. These products are so ubiquitous that it’s hard to envision life without them.

Professor Niels Damrauer and his CU Boulder and CSU research colleagues were inspired by photosynthesis in designing a system using LED lights to catalyze transformations commonly used in chemical manufacturing.

The process of transforming base materials into these desired products, however, has long come at significant environmental cost. Historically, catalyzing transformations in industrial processes has frequently used extreme heat to create the necessary energy.

Now, continuing to build on a growing body of research and discovery, �� scientists are many steps closer to using light instead of heat to catalyze transformations in industrial processes.

In a study recently published in Science, Niels Damrauer, a CU Boulder professor of chemistry and Renewable and Sustainable Energy Institute fellow, and his research colleagues at CU Boulder and Colorado State University found that a system using LED lights can catalyze transformations commonly used in chemical manufacturing. And it’s entirely possible, Damrauer says, that sunlight could ultimately be the light source in this system.

“With many transformations, the economics are, ‘Well, I need this product and I’m going to sell it at this price, so my energy costs can’t be larger than this amount to make a profit’,” Damrauer says. “But when you start to think about climate change and start to think about trying to create more efficient ways to make things, you need different approaches.

“You can do that chemistry with very harsh conditions, but those harsh conditions demand energy use. The particular chemistry we are able to do in this paper suggests we’ve figured out a way to do these transformations under mild conditions.”

Inspired by plants

Damrauer and his colleagues—including first authors Arindam Sau, a CU Boulder PhD candidate in chemistry, and Amreen Bains, a postdoctoral scholar in chemistry at Colorado State University in the group of Professor Garret Miyake—work in a branch of chemistry called photoredox catalysis, “where ‘photo’ means light and ‘redox’ means reduction and oxidation,” Damrauer explains. “This type of chemistry is fundamentally inspired by photosynthesis. A lot of chemistry—not all of chemistry, but a huge fraction of chemistry—involves the movement of electrons out of things and into other things to make transformations. That happens in plants, and it happens in photoredox catalysis as well.

“In photosynthesis, there’s a beautiful control over not only the motion of electrons but the motion of protons. It’s in the coupling of those two motions that a plant derives functions it’s able to achieve in taking electrons out of something like water and storing it in CO2 as something like sugar.”

Further inspired by photosynthesis and a plant’s use of chlorophyl to collect sunlight, the research team used an organic dye molecule as a sort of “pre-catalyst” that absorbs light and transforms into a catalyst molecule, which also absorbs light and accelerates chemical reactions. And because the four LED lights surrounding the reactor are only slightly brighter than a regular home LED lightbulb, the transformation process happens at room temperature rather than extreme heat.

The molecule is also able to “reset” itself afterward and harvest more light, beginning the process anew.

“We set out to understand the behavior of a photocatalyst that was inefficient at this process, and my student Arindam discovered there was this fundamental transformation to the molecule occurring while we did the reaction,” Damrauer says, adding that the team discovered there are key motions not just of electrons, which is essential for photoredox, but also of protons.

“In our mechanism, the motion of the proton occurs in the formation of a water molecule, and that very stable molecule prevents another event that would undermine the storage of energy that we’re trying to achieve,” Damrauer says. “We figured out what the reaction was and, based on that reaction, we started to make simpler molecules.

“This was a really fortuitous discovery process: We were studying something, saw a change, took the knowledge of what that change was and started to design systems that were even better. This is the best advertisement for basic science—sometimes you can’t design it; you’ve got to discover things, you’ve got to have that freedom.”

A sunny future

Damrauer, Sau and their colleagues in the multidisciplinary, multi-institutional Sustainable Photoredox Catalysis Research Center (SuPRCat) are continuing to build on these discoveries, which happen at a small scale now but may have the potential for large-scale commercial use.

In an essay for The Conversation, Sau noted, “Our work points toward a future where chemicals are made using light instead of heat. For example, our catalyst can turn benzene—a simple component of crude oil—into a form called cyclohexadienes. This is a key step in making the building blocks for nylon. Improving this part of the process could reduce the carbon footprint of nylon production.

“Imagine manufacturers using LED reactors or even sunlight to power the production of essential chemicals. LEDs still use electricity, but they need far less energy compared with the traditional heating methods used in chemical manufacturing. As we scale things up, we’re also figuring out ways to harness sunlight directly, making the entire process even more sustainable and energy efficient.”

Damrauer adds that he and his colleagues aren’t trying to change the nature of manufactured chemicals, but the approach to how they’re made. “We’re not looking at making more stable paint, for example, but we’re asking if it costs a certain number of joules to make that gallon of paint, how can we reduce that?”

In addition to Niels Damrauer, Arindam Sau and Amreen Bains, Brandon Portela, Kajal Kajal, Alexander Green, Anna Wolff, Ludovic Patin, Robert Paton and Garret Miyake contributed to this research.

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In research recently published in Science, CU Boulder scientists detail how light—rather than energy-intensive heat—can efficiently and sustainably catalyze chemical transformations.

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Top image: dreamstime.com

Supporting survivors of sexual assault through community

Rachel Sauer — Thu, 03 Jul 2025 00:31:29 +0000

Supporting survivors of sexual assault through community Rachel Sauer Wed, 07/02/2025 - 18:31

Cody DeBos

CU PhD graduate Tara Streng-Schroeter's research offers a new way to support survivors of sexual violence

The first time Tara Kay Streng-Schroeter stepped into a sorority house to deliver her sexual assault support training, she hoped it would help students feel more prepared to support one another.

She didn’t anticipate the crowd of women lining up afterward to ask questions and offer thanks.

“At one chapter, many women came up to me and thanked me for being there, told me how important they think this training is,” she recalls. “Some said it was better than any training they’ve received from school or as an RA (resident advisor).”

CU Boulder scholar Tara Streng-Schroeter, who earned a PhD in sociology in May, designed a peer-based intervention program designed to help students respond supportively when someone they care about discloses they have experienced sexual violence.

That moment reaffirmed Streng-Schroeter’s belief in what she’d spent years building: a peer-based intervention program designed to help students respond supportively when someone they care about discloses they have experienced sexual violence.

Her program, called Building Support for Survivors (BSS), offers a promising new approach to how college campuses can support students who experience sexual violence.

“We know the majority of survivors never seek support from the police or formal support from a non-profit or university resources. They instead disclose to a close connection,” Streng-Schroeter says.

Yet most students haven’t been trained to handle such a sensitive moment. Even well-intentioned responses can backfire, leading to shame, self-blame or isolation for survivors.

That’s the gap Streng-Schroeter, who in May earned her PhD in sociology from the ��, hopes to close.

Taking innovative research to the front lines

Streng-Schroeter has spent more than a decade working both professionally and academically in the field of sexual-violence response. She has coordinated sexual-assault response teams, trained volunteer victim advocates and witnessed firsthand the long-term effects of both harm and healing.

After talking with hundreds of survivors, she was acutely aware of the opportunity that existed to help college students support their peers who have experienced sexual violence.

Building Support for Survivors, a 90-minute training intervention that she designed to be implemented with peer groups of college students and has piloted with sorority chapters, combines education about the prevalence of sexual violence with hands-on learning around how to listen, what to say and what not to say.

As part of Building Support for Survivors, Streng-Schroeter also provides customized flyers listing local confidential and non-confidential support options.

“Even though there are so many victims within campus communities, students don’t necessarily know the right thing to say to someone who’s experienced this kind of violence unless they have received training,” she says. “And it’s those individuals that don’t have the training but need it that we’re trying to help.”

Over the course of her study, Streng-Schroeter partnered with sorority chapters at nine universities across the country, delivering her training in person at four of them.

A wake-up call

“We know the majority of survivors never seek support from the police or formal support from a non-profit or university resources. They instead disclose to a close connection,” says CU Boulder researcher Tara Streng-Schroeter.

One of the most striking findings of Streng-Schroeter’s research was just how many students have been affected by sexual violence. More than half of the sorority women who completed her surveys reported experiencing sexual violence in their lives.

That number is significantly higher than national averages had previously suggested.

“It could have happened in the week or the month or the semester leading up to when they took a survey,” Streng-Schroeter says, “but it also could have happened when they were a child, or when they were in high school.”

She notes that sorority members, as well as queer students, are disproportionately affected by sexual violence on college campuses. However, many studies only ask about incidents within a narrow time frame, obscuring the full picture.

“Knowing more about what the actual affected population looks like was very important to me,” Streng-Schroeter says.

The data from her study underscores the urgency of making peer support more effective. Fortunately, there are many promising signs that her intervention works.

Rethinking support for survivors

After completing Streng-Schroeter’s BSS training, students showed meaningfully improved responses in how they thought about and responded to sexual-assault disclosures.

Participants who received the training reported lower levels of rape-myth acceptance—the false or harmful beliefs about what “counts” as sexual violence or who is to blame.

“The program also increased how often participants in chapters that received the training actually provided positive responses to their friends’ disclosure of sexual victimization,” Streng-Schroeter says. “And the data also appears to show that the training reduced negative responses and reduced how often participants anticipate that they will use negative responses when faced with a disclosure of sexual violence in the future.”

Streng-Schroeter believes that her community-first training model is an essential part of why it’s so effective.

Unlike large, anonymous lectures, her program is delivered in already-formed social networks. She theorizes that within peer groups where trust already exists and that experience disproportionately high levels of sexual violence, individuals may be more likely to disclose being the victim of sexual violence to one another.

"Even though there are so many victims within campus communities, students don’t necessarily know the right thing to say to someone who’s experienced this kind of violence unless they have received training."

“The social community aspect is a really important aspect of why we saw promising results with this,” Streng-Schroeter says. “Deploying the exact same training in an orientation for new students … it wouldn’t have the same effect because those friendship networks aren’t there yet.”

In other words, the best way to support survivors may be to start with the people they already lean on by giving them the tools to respond appropriately.

Healing together

With her dissertation completed and defended, Streng-Schroeter now hopes to expand the BSS program. She believes the model could scale to more chapters—and other student communities where close peer-bonds exist—with more funding.

She says, “One goal is to secure funding so I can provide this training across a whole network of a sorority, every chapter. That could impact thousands of people’s lives.”

She’s also eager to adapt the training for queer student organizations, college athletic teams and other student clubs.

Streng-Schroeter knows institutional and cultural reform takes time. But helping students become better friends, listeners and supporters can happen right now.

“People just voluntarily sharing that they felt this training was impactful really meant a lot. It made me think, ‘Okay, something good is happening here,’” Streng-Schroeter says.

As her training and research show, the most important support doesn’t always come from an office or through official channels. Often, healing begins when one person is ready to talk and another is prepared to hear them.

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CU PhD graduate Tara Streng-Schroeter's research offers a new way to support survivors of sexual violence.

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Harnessing the abundant resource of sunlight

Rachel Sauer — Tue, 24 Jun 2025 17:55:24 +0000

Harnessing the abundant resource of sunlight Rachel Sauer Tue, 06/24/2025 - 11:55

Arindam Sau , Amreen Bains and Anna Wolff

Light-powered reactions could make the chemical manufacturing industry more energy-efficient

Manufactured chemicals and materials are necessary for practically every aspect of daily life, from life-saving pharmaceuticals to plastics, fuels and fertilizers. Yet manufacturing these important chemicals comes at a steep energy cost.

Many of these industrial chemicals are derived primarily from fossil fuel-based materials. These compounds are typically very stable, making it difficult to transform them into useful products without applying harsh and energy-demanding reaction conditions.

Arindam Sau, a Ph.D. candidate in the CU Boulder Department of Chemistry, along with Colorado State University research colleagues Amreen Bains and Anna Wolff, have been working on a system that uses light to power reactions commonly used in the chemical manufacturing industry.

As a result, transforming these stubborn materials contributes significantly to the world’s overall energy use. In 2022, the industrial sector consumed 37% of the world’s total energy, with the chemical industry responsible for approximately 12% of that demand.

Conventional chemical manufacturing processes use heat to generate the energy needed for reactions that take place at high temperatures and pressures. An approach that uses light instead of heat could lower energy demands and allow reactions to be run under gentler conditions — like at room temperature instead of extreme heat.

Sunlight represents one of the most abundant yet underutilized energy sources on Earth. In nature, this energy is captured through photosynthesis, where plants convert light into chemical energy. Inspired by this process, our team of chemists at the Center for Sustainable Photoredox Catalysis, a research center funded by the National Science Foundation, has been working on a system that uses light to power reactions commonly used in the chemical manufacturing industry. We published our results in the journal Science in June 2025.

We hope that this method could provide a more economical route for creating industrial chemicals out of fossil fuels. At the same time, since it doesn’t rely on super-high temperatures or pressures, the process is safer, with fewer chances for accidents.

How does our system work?

The photoredox catalyst system that our team has developed is powered by simple LEDs, and it operates efficiently at room temperature.

At the core of our system is an organic photoredox catalyst: a specialized molecule that we know accelerates chemical reactions when exposed to light, without being consumed in the process.

Much like how plants rely on pigments to harvest sunlight for photosynthesis, our photoredox catalyst absorbs multiple particles of light, called photons, in a sequence.

These photons provide bursts of energy, which the catalyst stores and then uses to kick-start reactions. This “multi-photon” harvesting builds up enough energy to force very stubborn molecules into undergoing reactions that would otherwise need highly reactive metals. Once the reaction is complete, the photocatalyst resets itself, ready to harvest more light and keep the process going without creating extra waste.

Designing molecules that can absorb multiple photons and react with stubborn molecules is tough. One big challenge is that after a molecule absorbs a photon, it only has a tiny window of time before that energy fades away or gets lost. Plus, making sure the molecule uses that energy the right way is not easy. The good news is we’ve found that our catalyst can do this efficiently at room temperature.

Enabling greener chemical manufacturing

CSU chemistry researcher Amreen Bains performs a light-driven photoredox catalyzed reaction. (Photo: John Cline/Colorado State University Photography)

Our work points toward a future where chemicals are made using light instead of heat. For example, our catalyst can turn benzene — a simple component of crude oil — into a form called cyclohexadienes. This is a key step in making the building blocks for nylon. Improving this part of the process could reduce the carbon footprint of nylon production.

Imagine manufacturers using LED reactors or even sunlight to power the production of essential chemicals. LEDs still use electricity, but they need far less energy compared with the traditional heating methods used in chemical manufacturing. As we scale things up, we’re also figuring out ways to harness sunlight directly, making the entire process even more sustainable and energy-efficient.

Right now, we’re using our photoredox catalysts successfully in small lab experiments — producing just milligrams at a time. But to move into commercial manufacturing, we’ll need to show that these catalysts can also work efficiently at a much larger scale, making kilograms or even tons of product. Testing them in these bigger reactions will ensure that they’re reliable and cost-effective enough for real-world chemical manufacturing.

Similarly, scaling up this process would require large-scale reactors that use light efficiently. Building those will first require designing new types of reactors that let light reach deeper inside. They’ll need to be more transparent or built differently so the light can easily get to all parts of the reaction.

Our team plans to keep developing new light-driven techniques inspired by nature’s efficiency. Sunlight is a plentiful resource, and by finding better ways to tap into it, we hope to make it easier and cleaner to produce the chemicals and materials that modern life depends on.

Arindam Sau is a Ph.D. candidate in the �� Department of Chemistry; Amreen Bains is a postdoctoral scholar in chemistry at Colorado State University; Anna Wolff is a PhD student in chemistry at Colorado State University.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Light-powered reactions could make the chemical manufacturing industry more energy-efficient.

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Healing Indigenous communities from the ground up

Rachel Sauer — Mon, 23 Jun 2025 23:46:02 +0000

Healing Indigenous communities from the ground up Rachel Sauer Mon, 06/23/2025 - 17:46

Sarah Kuta

Mushroom mycelium can clean up the soil. Can it also help Indigenous people reconnect to the land? CU Boulder researcher Natalie Avalos aims to find out

Fungi are powerful and versatile organisms. They’re being used in a variety of beneficial ways, from degrading hard-to-recycle plastics and purifying contaminated water to developing new medicines and restoring forests after wildfires.

Now an innovative project from the �� will explore fungi’s ability to remediate urban soil and, in the process, reconnect Indigenous families to the land.

The project is being led by Natalie Avalos, a CU Boulder assistant professor of ethnic studies and core faculty member of the Center for Native American and Indigenous Studies (CNAIS). She’s working in partnership with Carissa Garcia, a Denver-based writer, educator and combat veteran with Picuris Pueblo heritage.

CU Boulder researcher Natalie Avalos, an assistant professor of ethnic studies, is leading a project to explore fungi’s ability to remediate urban soil and, in the process, reconnect Indigenous families to the land.

With grant funding from CNAIS, the duo plans to use mushroom mycelium to clean up the soil at various locations in Denver and Commerce City. They hope to inoculate small farm plots and garden beds on properties that are owned or rented by Indigenous people.

Soil remediation will allow Indigenous families to grow their own foods and medicines and may even lead to the revitalization of ancient crops. But, beyond that, Avalos and Garcia hope their land-based healing project will help Indigenous people restore and strengthen their sacred relationship with the land.

“We talk about decolonization as land repatriation, or the return of Indigenous lands to Indigenous people,” says Avalos. “But this is a form of rematriation, thinking about land as mother and returning to this relationship where you are tending to the health and well-being of the mother so that she can better attend to your health and well-being in return. Restoring that symbiotic relationship is profoundly impactful for families.”

The power of fungi

Mycelium is the name for the network of dense, fibrous, root-like threads that make up the body of a fungus. It’s typically hidden underground, often out of sight and out of mind until it produces mushrooms, which grow above the soil and help fungi reproduce.

In the wilderness, mycelium acts as nature’s clean-up crew. It plays a vital role in decomposition, breaking down dead plants and returning essential nutrients to the soil.

But researchers have also come to realize that mycelium can be a powerful ally for combating pollution. The process, known as “mycoremediation,” harnesses fungi’s natural abilities to remove or break down harmful contaminants in the soil. Scientists are using fungi to clean up everything from heavy metals and pesticides to petrochemicals and other hazardous substances.

Avalos and Garcia want to use mycelium to create healthy and resilient soil for Indigenous families, including some that live in heavily polluted areas on Colorado’s Front Range. They plan to take detailed measurements before, during and after inoculation, to see how the mycelium affects the soil, as well as the plants that will eventually grow in it. Based on these initial results, they hope to expand their mycoremediation work to other Indigenous farms and gardens—and, possibly, even to tribal lands.

They also want to use the soil remediation project to create hands-on educational opportunities for Indigenous communities, particularly Indigenous youth.

Garcia will spearhead the soil remediation work, which is slated to begin later this year. Then, after the mycelium works its magic, Avalos will investigate how the project is affecting Indigenous people.

“I’ll start collecting some oral histories, some ethnographic testaments about what this means to them,” says Avalos. “How is this confirming their relationship to land? How is it speaking to or shaping their religious life, their sense of identity, their Indigeneity? How is it that having restored soil is supporting their health and wellness and contributing to human flourishing?”

“We talk about decolonization as land repatriation, or the return of Indigenous lands to Indigenous people. But this is a form of rematriation, thinking about land as mother and returning to this relationship where you are tending to the health and well-being of the mother so that she can better attend to your health and well-being in return. Restoring that symbiotic relationship is profoundly impactful for families.”

Sovereignty and self-determination

Avalos is also curious to learn how soil remediation might contribute to sovereignty and self-determination for Indigenous people, especially those living in cities. Today, roughly 70% of American Indians and Alaska Natives live in urban areas—but this population is often overlooked.

“How is it that Native people can act as stewards of land, even though they often have less control over that land?” Avalos says. “They may be renters, they may be living in very polluted areas. But just to have that little bit of agency.”

Denver sits on the ancestral homelands of the Arapaho, the Cheyenne, the Ute and other tribes. But, today, the city is home to Indigenous people with a wide array of tribal backgrounds. This diversity largely stems from a federal program that pushed Native Americans away from reservations and into urban areas in the 1950s and ‘60s, as part of the government’s broader attempts to force Indigenous people to assimilate. Denver was one of nine relocation sites located across the country.

“For folks living in cities that have been impacted by displacement and disconnection, I want to document, how are they reconnecting? How are they re-Indigenizing?” Avalos says.

As the world grapples with pressing environmental issues, many Indigenous people are now looking to their sacred ways of life for answers. Long displaced from their lands and separated from their traditional cultural practices, they’re returning to ancestral medicines, deepening their relationships with all living creatures and opening themselves up to the knowledge that’s embedded in the land.

Avalos and Garcia hope their soil remediation project might play a small role in that broader work.

“We can’t count on the treaties, we can’t count on our federal leadership or even our state leadership to really protect us and protect land,” says Garcia. “My generation is looking at a grim future. We’re at a place where many of us are asking, how do we embody the Indigeneity and our sacred ways of knowing and being, and mesh that with an Indigenous futurism that will heal the planet and our people?”

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Mushroom mycelium can clean up the soil. Can it also help Indigenous people reconnect to the land? CU Boulder researcher Natalie Avalos aims to find out.

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Top image: mycelium growing on a log (Photo: iStock)

CU Boulder scientist receives $1.25 million award for cancer research

Rachel Sauer — Wed, 18 Jun 2025 17:12:44 +0000

CU Boulder scientist receives $1.25 million award for cancer research Rachel Sauer Wed, 06/18/2025 - 11:12

Edward Chuong is one of five researchers nationwide awarded funding to pursue ‘daring, paradigm-shifting research’ on cancer immunotherapy treatment

Edward Chuong, a �� assistant professor of molecular, cellular and developmental biology and a BioFrontiers Institute scientist, has been awarded $1.25 million by the New York City-based Cancer Research Institute (CRI) to pursue his cancer immunotherapy research.

Chuong was one of five researchers nationwide who received the unrestricted funding over a five-year period, which CRI said is designed to allow researchers to pursue high-risk, high-reward projects that could redefine cancer treatment. The organization called the researchers “scientific leaders poised to reshape cancer immunotherapy through daring, paradigm-shifting research.”

Edward Chuong, a CU Boulder assistant professor of molecular, cellular and developmental biology and a BioFrontiers Institute scientist, recently was awarded $1.25 million by the Cancer Research Institute to pursue cancer immunotherapy research.

“These are people who are hitting their stride scientifically and career-wise, and this is where you really want to put some jet fuel in the tank as they are getting established,” said Dr. E. John Wherry, associate director of CRI’s Scientific Advisory Council.

Echoing Wherry’s sentiment, Dr. Alicia Zhou, CRI chief executive officer, added, “Each of these researchers brings fearless curiosity and a willingness to challenge assumptions – the very qualities that drive breakthroughs. They aren’t just advancing cancer science; they are reinventing it.”

Chuong said he was surprised and honored to receive CRI funding for his research.

“As someone from an evolutionary biology background, this award means my outsider ideas are being welcomed into the cancer research community. It’s a huge boost,” he said.

Chuong’s research focuses on the role that ancient viral fragments in human DNA, called transposons, play in regulating immune cell signaling.

“Our lab started out exploring the evolution of transposons—bits of DNA derived from genetic parasites—and discovered they may function as hidden switches in our immune system,” Chuong said. “With this support, we’ll investigate how cancer cells hijack these switches to escape detection, and use that knowledge to develop new markers and therapies that make immunotherapy work better for more patients. I’m grateful to the Cancer Research Institute for supporting this unconventional perspective and I’m incredibly excited to see where it leads.”

Each year, CRI awards funding for scientists to pursue their research through its grant-making program honoring its founding scientific and medical director, Lloyd J. Old. The organization said its Lloyd J. Old STAR program—Scientists TAking Risks—is designed to provide long-term funding to mid-career scientists, giving them the freedom and flexibility to pursue research “at the forefront of discovery and innovation in cancer immunotherapy.”

CRI said its awards are given out based upon its “exceptional track record of identifying and supporting people who have had a major impact in immunotherapy.” The organization said its grants are not tied to a specific research project but rather support outstanding researchers based upon the quality and promise of researchers’ overall work.

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Edward Chuong is one of five researchers nationwide awarded funding to pursue ‘daring, paradigm-shifting research’ on cancer immunotherapy treatment.

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Farm-diversification research wins top international prize

Rachel Sauer — Tue, 17 Jun 2025 16:03:33 +0000

Farm-diversification research wins top international prize Rachel Sauer Tue, 06/17/2025 - 10:03

Clint Talbott

CU Boulder’s Zia Mehrabi is one of three researchers named international champions of the Frontiers Planet Prize for research that finds environmental and social benefits of agricultural diversification

Widespread agricultural diversification could improve the health of the world’s environment and that of its people, a landmark study published last year found.

Zia Mehrabi, assistant professor of environmental studies at the ��, has been named one of three international champions in the Frontiers Planet Prize, the Frontiers Research Foundation announced today. Mehrabi and his team will receive $1 million in funding to advance their research.

The Frontiers Planet Prize celebrates breakthroughs in Earth system and planetary science that “address these challenges and enable society to stay within the safe boundaries of the planet’s ecosystem.” The prize puts scientific rigor and ingenuity at its heart, helping researchers worldwide accelerate society toward a green renaissance, the Frontiers Research Foundation says.

Zia Mehrabi, a CU Boulder assistant professor of environmental studies, has been named the U.S. national champion for the Frontiers Planet Prize.

Professor Jean-Claude Burgelman, director of the Frontiers Planet Prize, said the planet faces immense threats that require bold, transformative solutions rooted in evidence and validated by science.

“Innovative yet scalable solutions are the only way for us to ensure healthy lives on a healthy planet,” Burgelman said. “By spotlighting the most groundbreaking research, we are helping scientists bring their work to the international stage and provide the scientific consensus needed to guide our actions and policies.”

Mehrabi, who leads the Better Planet Laboratory, was recognized, alongside his co-authors, for an article published last year in the journal Science titled “Joint environmental and social benefits from diversified agriculture.”

Laura Vang Rasmussen of the University of Copenhagen in Denmark and Ingo Grass of the University of Hohenheim in Germany were lead authors of the paper, which had 58 co-authors. Claire Kremen of the University of British Columbia was a senior author and co-principal investigator on the study.

The researchers found that diversifying crops and animals and improving habitat, soil and water conservation on individual farms can improve biodiversity while improving or, at a minimum, not coming at a cost to yields. Additionally, diversified farming can yield social benefits and improve food security—showing improved food access or a reduced number of hungry months, for example, particularly in smallholder systems.

The more diversification measures farms employed, the more benefits accrued, researchers observed. Essentially, the team found evidence to move toward agriculture that more closely reflects natural systems.

“If you look at how ecosystems operate, it’s not just plants growing alone. It’s not just animals or soil,” Mehrabi said last year. “It’s all of these things working together.”

Using data from 2,655 farms across 11 countries and covering five continents, the researchers combined qualitative methods and statistical models to analyze 24 different datasets. Each dataset studied farm sites with varying levels of diversification, including farms without any diversification practices. This allowed the team to assess the effects of applying more diversification strategies.

Diversified farming differs from the dominant model of agriculture: growing single crops or one animal on large tracts of land. That efficient, “monoculture” style of farming is a hallmark of agriculture after the Green Revolution, which reduced global famine by focusing on high-yield crops that rely on fertilizers and pesticides.

“The Green Revolution did many, many great things, but it came with a lot of costs,” Mehrabi says, noting that synthetic fertilizers and pesticides harm the environment.

Also, to increase labor productivity, large farms rely on mechanization, which tends to “replace people with machines.”

“So, the idea of trying to engineer nature into our agricultural systems is somewhat antithetical to the whole way we think about agricultural development,” Mehrabi says.

Making a case for a different way of doing agriculture is one thing. Implementing it on a widespread basis is something else. The dominant view, fostered by “big ag” (short for agriculture), is that “if you want to do ag, you’ve got to do it this way,” Mehrabi says.

“If you look at how ecosystems operate, it’s not just plants growing alone. It’s not just animals or soil. It’s all of these things working together,” says Zia Mehrabi.

“Our work challenges that idea, but it’s a bit of a David-and-Goliath situation,” he adds. “We have the stone, but it hasn’t yet landed.”

But it’s necessary to confront Goliath, Mehrabi contends, noting that agriculture affects all the things people care about environmentally, including climate change, water security, biodiversity, pollution, land use and habitat destruction.

A third of the Earth’s land is used for agriculture, and about a quarter of greenhouse gas emissions stem from agriculture, he notes. Climate change has reduced agricultural yields by as much as 5% to 10% in the last four decades, research has shown.

“If we want to do something about environmental issues, agriculture is one of the big buckets that we need to really, really start in.”

Separate from the research published in Science, Mehrabi has done modeling of the future state of agriculture globallyif the world continues business-as-usual farming. He found that in the next century, the number of farms is likely to be cut in half and the average size of farms would likely double.

Given that, along with what scientists know about the loss of natural ecosystems as farm sizes increase, “the future looks a little bit bleak,” Mehrabi says. But this new research shows it could be different.

Though he does not suggest that all farms must be small farms, he does advise that agriculture strive to diversify systems that have been “massively depleted and massively simplified.”

�� the Frontiers Planet Prize, Mehrabi says he and his team are gratified to be recognized as one of three international champions. Additionally, he underscores the importance of the Frontiers Research Foundation’s financial commitment to this kind of research, calling it a “signal” to other funding entities that might follow suit.

“We need to really think about innovation in agriculture,” Mehrabi said. “We all need food to eat. We really need to innovate, and we should put money behind that. It’s worth it.”

Launched by the Frontiers Research Foundation on Earth Day 2022, the prize encourages universities worldwide to nominate their top three scientists working on understanding and putting forward pathways to stay within the safe operating space of nine planetary boundaries that are outlined by the Stockholm Resilience Center.

These nominations are then vetted at the national level, and the top scientists face an independent jury of 100—a group of renowned sustainability and planetary health experts chaired by Professor Johan Rockström—who vote for the National and International Champions.

Read a guest opinion by Zia Mehrabi and co-authors at this link. See a Q&A with Mehrabi about adding carbon-footprint labels on food at this link.

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CU Boulder prof named Boettcher Investigator

Rachel Sauer — Fri, 06 Jun 2025 18:38:17 +0000

CU Boulder prof named Boettcher Investigator Rachel Sauer Fri, 06/06/2025 - 12:38

Assistant Professor Jennifer Hill is one of seven Colorado researchers to be recognized by the Boettcher Foundation for their pioneering biomedical research

The Boettcher Foundation and Colorado BioScience Association (CBSA) have named Assistant Professor Jennifer H. Hill with the ��’s Department of Molecular, Cellular and Developmental Biology and BioFrontiers Institute as one of seven outstanding early-career biomedical researchers.

Each scientist will receive a $250,000 grant through the Boettcher Foundation’s Webb-Waring Biomedical Research Awards Program to support up to three years of independent scientific research, with total grant funding reaching $1.75 million.

CU Boulder scientist Jennifer Hill, an assistant professor of molecular, cellular and developmental biology, has been named a 2025 Boettcher Investigator.

“It’s a huge honor to be selected as one of this year’s Boettcher Investigators, especially given the depth of groundbreaking biomedical research in Colorado,” Hill said. “The award gives my lab the resources to explore the relevance of our work in human tissues, bringing us closer to our goal of preventing type 1 diabetes in children. As a young investigator, receiving funds like these goes a long way to help offset some of the anxiety and uncertainty in the current federal funding landscape.”

This year’s class represents the next generation of scientific excellence and marks another milestone in Boettcher Foundation’s 16-year commitment to strengthening Colorado’s biomedical research ecosystem, according to the Boettcher Foundation. The Webb-Waring Biomedical Research Awards provide crucial early-career support and position recipients to compete for additional private, state and federal research funding.

“We are delighted to support our 2025 Boettcher Investigators, and as champions of their work, we are confident that these researchers will continue to spark new discoveries and drive innovation in medicine,” said Katie Kramer, president and CEO of the Boettcher Foundation. “The far-reaching impact of our Investigators’ research extends well beyond the lab—each advancement sets in motion a ripple effect that benefits patients, strengthens Colorado’s scientific community, and inspires future breakthroughs. We are proud to invest in these remarkable scientists, whose dedication and creativity are shaping a healthier future for all.”

Hill is a microbe scientist who studies the connection between the pancreas and microbes in the gut, examining microbiota in the development of insulin-producing beta cells. Four Boettcher Investigators with the University of Colorado Anschutz Medical Campus and two with Colorado State University are pursuing research into fields including osteoarthritis, autism spectrum disorder, cancer and autoimmune diseases, and developmental and neurological disorders.

Since its inception, the Webb-Waring Biomedical Research Awards Program has supported 113 Boettcher Investigators, including this year’s class, and awarded close to $27 million in grant funding. These researchers have gone on to secure more than $150 million in additional research funding from federal, state and private sources, according to the Boettcher Foundation.

“Colorado BioScience Association is grateful to the Boettcher Foundation for its continued investment in the next generation of scientific leaders in our state,” said Elyse Blazevich, president and CEO of Colorado BioScience Association. “The Webb-Waring Biomedical Research Awards provide essential early-career funding that empowers researchers to remain in Colorado and advance their discoveries within our world-class academic and research institutions. We are honored to celebrate the accomplishments of the 2025 class of Boettcher Investigators.”

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Assistant Professor Jennifer Hill is one of seven Colorado researchers to be recognized by the Boettcher Foundation for their pioneering biomedical research.

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Tree rings offer clues to small-population growth

Rachel Sauer — Thu, 05 Jun 2025 15:54:21 +0000

Tree rings offer clues to small-population growth Rachel Sauer Thu, 06/05/2025 - 09:54

Daniel Long

In a recently published paper, PhD student Ellen Waddle and her coauthors provide some clarity on a decades-old problem

When researching what drives the growth of small populations, ecologists consider several factors, says Ellen Waddle, a PhD student in the ��’s Department of Ecology and Evolutionary Biology.

“There’s climate. There’s density, which can be thought of as both the total number of individuals in a population or how crowded or spread out individuals are. And then there’s stochasticity, which is this big word that just means variance” or random chance.

CU Boulder scientists Ellen Waddle (left), a PhD student in ecology and evolutionary biology, and Dan Doak (right), a professor of environmental studies, and their research colleagues found "that climate data alone did a pretty poor job of predicting population growth (in small tree populations)."

But whether any of these drivers matters more than the others is a question that has challenged researchers since at least the 1950s, and one that Waddle and her coauthors Mark R. Lesser, Christopher Steenbock and Dan Doak take up in a paper recently published in Ecology and Evolution.

Time and perspective

Researchers have tended to fall into opposing camps with this question, Waddle explains.

“There’s a lot of people that think if we can perfectly predict what the climate’s going to be in an area, we’re going to be able to perfectly predict how that population is going to grow through time. And then you have another set of ecologists that argue, well, it also really matters how many individuals you have in the population.”

Yet in their paper, Waddle and her coauthors come to a less divisive conclusion. By analyzing the rings of two long-lived tree species, Ponderosa pine and limber pine, “we found that climate data alone did a pretty poor job of predicting population growth. We needed to include other drivers (in our predictive models), like competitive density effects and stochasticity, to accurately reconstruct population dynamics over time.”

This means that no individual driver proved more influential than the others. They all mattered.

Which was somewhat surprising, Waddle says, considering the long timescale she and her colleagues were dealing with—many hundreds of years. (The oldest tree they sampled dates back to 1470, half a century before Queen Elizabeth I was born.)

“We're averaging over such a long timeframe that you might be tempted to think that random fluctuations and stochasticity are less important, but this sort of study highlights that that's not always true. There's a lot of uncertainty in how long it's going to take small populations to grow.”

“The most important aspect of our work, to my mind,” adds Doak, professor of environmental studies at CU Boulder and head of the Doak Lab, “is showing that simplifying assumptions we often make about population growth don’t seem to hold up.”

‘The entire history of a tree’s life’

Tree rings, says Waddle, are a gold standard for measuring a tree’s history, one with which most people are familiar. The center, or pith, signifies when the tree established, or secured its roots and became capable of growing on its own, and each concentric ring around it represents a year of growth.

CU Boulder researchers studied small populations of Ponderosa pine (seen here) and limber pine to better understand how drivers such as climate data and competitive density affect growth. (Photo: Wikimedia Commons)

But for their study, Waddle and her coauthors used tree rings—in the form of tree cores, or centimeter-wide rods extracted from living tree trunks—a little differently.

“What we did, which has not been done often, was to core every single tree in the population,” says Waddle, which enabled her and her coauthors to get a clearer picture of how tree populations changed over time than they would have gotten coring only a handful of trees.

“Another way to put it: The tree core data basically allows us to reconstruct annual censuses of population from start (1400s-1500s) through present day because we can know exactly how many individuals were alive in each year and when each individual first established.”

The tree-core samples themselves came from Bighorn Basin, a mountain-encircled plateau region in north-central Wyoming about 500 miles from Boulder. Waddle collected some of the tree cores herself in 2017, while an undergrad at CU, for what turned out to be her first camping experience.

Yet the bulk of the core samples owe their existence to Lesser and Steenbock. Lesser alone cored around 1,100 Ponderosa pines between 2007 and 2008, in hot, sometimes tense conditions.

“We (Lesser and an undergraduate field technician) would start hiking to the first trees of the day typically around 5 a.m. to avoid the worst of the heat,” Lesser recalls. “Trekking up dry streambeds to reach the trees we would encounter multiple rattlesnakes each morning and on one occasion a mountain lion that set us on edge for the rest of the day! Many days we would core fewer than 20 trees due to the low density of the population and the ruggedness of the terrain—getting from one tree to the next often took an hour or more negotiating cliff faces, ravines and steep slopes.”

But the effort, he says, was worth it.

“Coring the trees itself was an incredibly rewarding experience—sizing up the tree to get a sense of its shape and where the pith was and then extracting the entire history of its life!”

Pick a species, any species

This research on small-population growth is no small matter, says Doak, “because all populations start small,” and “understanding what controls the growth of new populations has a new urgency as we try to predict whether wild species can shift their ranges to keep up with climate change.”

“Pick some species you care about,” says Waddle, who is currently writing her dissertation on how mountain terrain affects plant species’ ability to follow their preferred climate. “What I care about might be different than what someone else cares about, but there’s probably a species that matters to you, whether it’s a food species or your favorite animal.

“If we want to help keep those populations on the landscape, we need to know how small populations grow and how they persist.”

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In a recently published paper, PhD student Ellen Waddle and her coauthors provide some clarity on a decades-old problem.

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