A cracker jack team of U of U undergrads works with principal investigator Ben Myers to break open a decades-old biological mystery of Hedgehog Signaling.

Corvin Arveseth

Corvin Arveseth, BS’21, can’t remember when he wasn’t fascinated by science and biology. So, when he came to the University of Utah and declared his majors in biology and biochemistry, he knew he wanted hands-on experience in research. “I didn’t know anything [about the] Hedgehog (Hh) signaling [pathway] until I read an advertisement put out by Ben Myers, [principal investigator at Huntsman Cancer Institute, assistant professor of oncological sciences at the University of Utah, and head of the Myers Lab] in a biology department newsletter looking for undergraduate researchers,” he says. “After reading some background information and meeting with Ben about the Hh pathway, I became intrigued with the work being done in his lab.”

The Hh pathway he’s referring to is akin to a master set of instructions for animal development and regeneration. It controls the formation of nearly every organ in the human body. Signaling pathways like Hh serve as molecular “telephone wires” from the cell surface to the nucleus. When cells in our bodies communicate with one another, signals are relayed along these molecular telephone wires, turning on expression of genes involved in growth, differentiation, or in some cases skin and brain cancers.

Corvin Arveseth and Will Steiner

The Hh pathway got its unusual name from decades-old genetic studies in fruit flies, where mutations in critical developmental genes led the flies to take on a bristly hedgehog-like appearance. However, versions of the Hh pathway operate throughout the animal kingdom, controlling development, stem cell biology, and cancer in many different contexts.

But even after many years of effort by labs all over the world, surprisingly little was known about how the Hh pathway actually works at a molecular level. Scientists knew that the signals conveyed by these molecular telephone wires were fundamental to human development and disease, but they didn’t know what the signals were, or how they were transmitted intracellularly. Consequently, health researchers’ ability to control Hh signaling in many diseases including cancer had been limited.

So, this is a story not just about a seemingly intractable research question, which is de rigeur in scientific circles, but how a team of largely undergraduate students in a four-year-old lab worked together under enormous odds to shake loose that answer. Myers says that that it was because of inexperience, not in spite of it, that the undergraduates in his lab were able to make these discoveries. These students’ fresh, undaunted determination to scientific inquiry, combined with a lack of preconceived notions and a willingness to learn, were key factors that enabled their groundbreaking discoveries.

Two papers, both with U undergraduates as first or co-first authors, were the gratifying result. PLOS Biology and Nature.com

Ben Myers

“It is a truly remarkable and inspiring collaboration that continues to this day, and I am so proud of how everybody was able to join forces and overcome so many obstacles created by the COVID-19 pandemic.”

Mysterious pathways
When Myers first set up his lab at the U in 2018, the key molecule in the Hh pathway that grabbed his attention was SMOOTHENED (SMO), a so-called “transmembrane protein” that spans across the cell membrane from the outside to the interior. SMO was known to be critical for transmitting signals from the cell surface to the nucleus. But what were the five or six steps between receiving the message and turning on gene expression? There was a “major disconnection about how this worked,” says Myers.

Nate Iverson

The twenty-five-year-old mystery was indeed tantalizing. It was “this interesting mystery coupled with the importance of Hh function,” says Arveseth, “in developmental and cancer biology [which] hooked me right away.”

Spearheading the project
Arveseth was the point of the spear for this project begun at the beginning of his sophomore year. But there were many others on the team, all of whom are “both incredibly smart, and also very kind and a lot of fun to work with,” according to Myers.

This includes Nate Iverson, a third year chemistry major with an interest in cellular signaling. “Having HCI in close connection with the University gave me greater access to research possibilities, and I was able to find an opening in the Myers lab studying Hh signal transduction.”

And then there was biology major Isaac Nelson, who worked tirelessly to produce a freezer full of carefully prepared, purified fragments of SMO for biochemical studies, only to hit a brick wall when he and Myers were unable to formulate a good hypothesis to drive an experiment.

Isaac Nelson

“It was only after starting up an international collaboration,” says Myers, “that the critical experiments snapped into view for us.” This led Nelson to send his samples to one of the lab’s new collaborators in Germany, and they used his samples to try an experiment that worked right away. In the midst of a raging pandemic, Nelson’s purified proteins helped to launch a new and entirely unexpected phase of the project, expanding the collaboration to include other scientists around the world.

“It was another scenario,” says Myers, “where everyone worked well together.”

Recent graduate Madison “Madi” Walker, BS’21, with a cell and molecular emphasis, was also part of the team. She is still working in the Myers lab studying another critical aspect of SMO signaling, namely the interaction between SMO and the enzyme G protein-coupled receptor kinase 2. Earlier, former undergraduate Jacob Capener, BS’20, assisted in the work.

Another critical member of the Myers lab team is Will Steiner, BS’21, who is currently collaborating with Arveseth and Nelson to purify SMO in complex with its binding partners in order to work out their atomic structures. He became interested in this area of research after taking the cell biology and biochemistry course at the U. “Biochemistry was particularly compelling and got me excited about the chemical reactions behind human physiology,” he says.

Madison Walker

It starts in the classroom
Rigorous courses were critical in preparing Myers’ undergraduate team for the hands-on research that led to their remarkable findings in the lab. He has nothing but kudos for the U’s curriculum. “Coursework before the lab experience [for undergraduate researchers] was very, very good here. In general, I’ve been lucky to attract motivated and curious students to my lab. They are inspired to push the research forward. They are all up to the challenge. And they have a great esprit de corps. They all work incredibly well together as a team to drive the science forward.”

That kind of correlated teamwork was not necessarily easy to enact under the circumstances. “Fortunately, we were able to finish the last key experiment of the first paper,” says Myers, in March 2020, just before the pandemic started to take hold and shut lab work down. He’s always believed that having undergraduates get a taste of cutting-edge research is important. They “shouldn’t have to work on something trivial… . What’s exciting about science is to push the boundaries.”

And yes, for Myers and the other senior members of his lab, including graduate students Danielle Hedeen and Aram Centeno, lab manager Ju-Fen Zhu, and former lab technician John Happ, “you have to be committed to helping everybody in your lab, even if they’re neophytes.” Clearly it’s been worth it. “And being a little bit of a neophyte is good,” he says, “because you don’t talk yourself out of doing experiments that are simple, unorthodox.”

Will Steiner

Asking the right questions
What Myers is trying to say, and seems to have proven over the course of the past three years and now the publication of two discovery-laden papers, is that their remarkable findings stemmed from the initial naïve view that the SMO protein didn’t fit the mold of other proteins as was previously assumed. He and Arveseth took a guess that SMO might be directly coupled to a critical intracellular signaling molecule called PKA. This was a rather wild idea, since there were few if any examples of transmembrane proteins that directly interacted with PKA. “It was a guess, how it might work, and a couple of months later: big discovery. Our initial guess was on the right track. There was a whole new unexpected thing going on but that made sense.”

Though early on the team suspected what they had discovered was important, “we didn’t know if we had a full explanation of how the system worked. We weren’t sure if it was the main event or an auxiliary event.” In the first paper, published in the journal PLOS Biology last year, they explained that: what they thought they knew, and what they weren’t sure about . . . yet.

But it was only after the pandemic was in full force that the team pivoted to the second exciting phase of the project, expanding to include Susan Taylor’s lab at the University of California, San Diego, one of the world’s foremost authorities on the PKA molecule the Myers team had implicated in their research.

Taylor and her colleagues had a critical insight regarding the SMO-PKA interaction which eventually formed the basis of a second manuscript, recently published in Nature Structural and Molecular Biology. “It is a truly remarkable and inspiring collaboration that continues to this day, and I am so proud of how everybody was able to join forces and overcome so many obstacles created by the COVID-19 pandemic,” says Myers. And his team is anticipating that even more exciting discoveries are on the horizon. Eventually, this work may lead to better drugs to treat some of the diseases that result from aberrant Hh signaling, including various skin and brain cancers.

In all, with the resulting two papers, the project turned out to be a “best case scenario that wasn’t planned,” and a lesson of how important it is to keep an open mind, which often leads to big discoveries.

Success is never final, however. And Arveseth, recipient of no less than ten scholarships and awards during his sojourn at the U, is now enrolled in the MD/PhD program at the Washington University in St. Louis, where he will focus on hematology and oncology. His colleagues are also pursuing their academic and research careers full-steam ahead. They, along with their mentor, Ben Myers are a testament to the notion that persistence in knowledge gathering pays off but that it must be paired and even driven by a relentlessly open mind.

The Meyers Lab

Concludes Myers, “To be honest, it comes down to the willingness to try new things and to have the ability to work together as a team. In reality, this would have been way too much for any individual scientist, even a highly trained one, to do alone.” You can follow him and his lab on Twitter @Myers_lab

Find the full study here.

Hooded Vulture

The decline of vultures and rise of dogs carries disease risks.

In the yards behind the slaughterhouses—also called abattoirs—of Ethiopia, an ecological shift is unfolding that echoes similar crises the world over. Species with a clear and effective ecological role are in serious decline, and the less-specialized but more aggressive species that have moved in to take their place are not only less effective, but are harmful to their ecosystem which, in this case, includes humans.

This is a story about vultures, feral dogs, rabies—and piles of rotting animal carcasses. Buckle up. But in the end, it’s about the power of conservation to keep ecosystems, even urban ecosystems, in balance, benefitting the people who live there.

“Carrion consumption by vultures is declining, and increasing by most other scavengers, but that increase is not sufficient to make up for the loss of vultures.” says SBS alumnus Evan Buechley, PhD’17, now with The Peregrine Fund, “So there’s a gap there. And what happens with that gap is a bit of an unanswered question, but that’s where the problem lies.”

The study is published in the Journal of Wildlife Management and is funded by the National Science Foundation, the University of Utah, HawkWatch International, The Peregrine Fund and the National Geographic Society.

Vultures are awesome

Worldwide, vultures are perfectly equipped to take care of the unpleasant remnants of death. Rotting carcasses can become hotbeds of disease, overrun by bacteria and insects. But vultures are an efficient clean-up crew. By eating carrion, they remove the carcasses and pass them through a highly acidic digestive system that wipes out disease-causing agents. And a diversity of vultures is better—some species are specialized to tear away hides and skin while others, coming in last, literally gulp down the bones.

Evan Buechley

“Carrion consumption by vultures is declining, and increasing by most other scavengers, but that increase is not sufficient enough to make up for the loss of vultures.”

But vultures have been in trouble in recent decades. They’re susceptible to poisons in the carrion they eat, whether that’s lead ammunition, the drug diclofenac, or poisons used against predatory animals. And with vultures producing relatively few chicks and taking a relatively long time to mature, it’s harder for them to recover from population declines.

Çağan Şekercioğlu, associate professor in the University of Utah School of Biological Sciences, showed that vultures were the most threatened group of birds (called an ecological guild, when the group uses the same or related resources) in 2004 when he conducted the first known ecological analysis of all bird species while in graduate school.

In 2012, Şekercioğlu accepted Buechley as his first doctoral student at the U. Buechley brought extensive experience working with vultures and condors. He and Şekercioğlu began a project tracking Egyptian vultures in eastern Turkey and the Horn of Africa.

“Evan led this project brilliantly and expanded it to the other vulture species of Ethiopia and the Horn,” Şekercioğlu says. “Despite the many challenges, he also decided to study the scavenger communities of the Addis Ababa abattoirs, to quantify the causes and consequences of vulture declines in the region.”

In 2016, Şekercioğlu and Buechley re-analyzed the ecology of all bird species. “We realized that vultures not only have the fewest species of any avian ecological guild, making them irreplaceable, but since that first analysis in 2004, they had gone downhill faster than any other group,” Şekercioğlu says.

Yes, there are other scavenger species that can take vultures’ place at the carrion table. But the loss of vultures, as we’ll see, can lead to human costs.

A white-backed vulture, a hooded vulture and a thick-billed raven.

Abattoirs’ feathered “employees”

At the abattoirs of Ethiopia, vultures are welcome partners. After butchering animals in clean conditions, the workers move the remnants of the carcasses – hooves, organs and bones, for example, to separate compounds. It’s a . . . unique sensory experience, Buechley says.

“It can be pretty stinky and pretty gross, by any objective measure.”

So abattoirs are grateful for the scavengers, including critically endangered white-backed, Rüppell’s and hooded vultures, that eagerly clean up the pile.

Study co-author Alazar Daka Ruffo, from Addis Ababa University, has interviewed abattoir staff members to see how they feel about the vultures.

“Some abattoir staff say half-jokingly, but not fully, that they see the vultures as employees of the abattoir,” says Buechley, reporting Ruffo’s findings. “They’re serving an important function. There’s intentionality behind the system.”

Other winged scavengers frequent the disposal piles, including crows, ravens, ibises and marabou storks. Four-legged visitors include packs of feral dogs.

“It’s an urban ecology situation where you have the human food supply meeting and really directly interacting with the wildlife food supply of scavengers,” Buechley adds. “It’s just a really complicated, kind of gross but fascinating system.”

With a research team including Rebecca Bishop, Tara Christensen and Şekercioğlu from the U’s School of Biological Sciences, Buechley set out to quantify the amount of carrion consumed by scavengers at six abattoirs in Ethiopia over five years, from 2014 to 2019.

Decline in vultures and rise in rabies

The team noted the types and abundance of scavengers that visited the abattoir buffets, and used this to extrapolate how much they ate. At first, vultures were eating more than half of the carrion in the disposal piles. White-backed, Rüppell’s and hooded vultures together ate an average of around 550 pounds (250 kg) of carrion a day.

But by the end of the five-year study, the number of Rüppell’s and white-backed vultures visiting the abattoir disposal yards decreased by 73%. Hooded vulture visits decreased by 15%. Over the same time, feral dog detections more than doubled.

A committee of hooded vultures.

“Although we can’t say for sure if the decline represents a population crash or if the vultures are being displaced by dogs and moving away from the abattoirs, either way this is really concerning,” says Megan Murgatroyd, Interim Director of International Programs for HawkWatch International.

“We know that the vultures are declining and we know that the feral dogs are increasing, but we don’t know exactly why,” Buechley says, adding that abattoir practices are also changing and that further studies will be needed to draw a cause-and-effect relationship.

Regardless, the vultures can ill afford the loss of abattoirs as a food supply. Rüppell’s, white-backed and hooded vultures are listed as critically endangered. “That’s the highest threat category before going extinct or extinct in the wild,” Buechley says.

The population of Rüppell’s vultures has declined by over 90% over the past three generations (approximately 40 years). White-backed and hooded vultures are doing a little better—but not by much. They’re estimated to have declined by 81% and 83%, respectively, over three generations.

“So it does seem that their disappearance from abattoirs is likely linked to a population crash,” says Murgatroyd. “Vultures need all the help they can get right now, and having to compete with growing dog populations is only making things worse.”

Other scavengers on the rise, including dogs, ibises and corvids (crows and ravens) couldn’t pick up the slack at the abattoirs. By 2019, scavengers were consuming nearly 43,000 pounds (around 20,000 kg) less carrion per year than they were in 2014, back when vultures were more abundant and dogs more scarce.

A chilling consequence of the rise of dogs may be a rise of rabies rates in humans. In the late 1990s, vulture populations in India and Pakistan crashed. Feral dog populations increased to take advantage of the uneaten carrion.

“They’re also disease vectors,” Buechley says, “and they interact really closely with people. And there’s been a link drawn between a big spike in feral dog populations and rabies in India.”

Is the same thing likely to happen in Ethiopia? Scientists haven’t yet drawn a link between vulture loss and rabies rise in that country. But Ethiopia already bears a heavy rabies burden with around 3,000 deaths from the disease per year.

“Unlike a lot of diseases which impact the elderly, rabies disproportionately affects young children, which are the most likely to be bit by rabid dogs,” Buechley says.

Fencing dogs out

The researchers provide a straightforward recommendation to help the situation: Use fences to keep the dogs out. And many abattoirs already have fences in place.

“But a pack of feral dogs is really persistent,” Buechley says. “It’s hard to keep hungry animals away from lots of food.”

An abattoir disposal pile with a kettle of vultures overhead.

The dogs can fight and dig their way through many fences, and maintaining or fortifying them may cut into the abattoirs’ profit margins.

“It’s a matter of weighing how important it is to keep the fences maintained,” Buechley says. “Improvement of these fences could really have a lot of benefits.” Those include potentially reducing the numbers of feral dogs, which reproduce quickly and whose population keeps pace with the available food supply. That in turn could help control rabies in humans and diseases in other animals, such as the critically endangered Ethiopian wolf, which are carried by the feral dogs.

And, counterintuitively, fencing out the abundant dogs could increase the rates of carrion consumption. Without the dogs around to scare off other scavengers, vultures could return in larger numbers to more quickly and efficiently clean up the disposal piles.

“That could lead to less smell, less groundwater contamination, fewer insects like flies that can breed on the carcasses,” Buechley says. “There’s a lot of potential benefits of investing in repairing the fences around abattoirs, which are found throughout Africa and elsewhere worldwide. We encourage abattoirs, local governments and international organizations to consider this when looking for solutions to waste disposal, human health and scavenger conservation.”

The results of the study show that the loss of specialist species from an ecosystem can’t always be compensated for by other species.

“The overarching point is that vultures are super important,” Buechley says. “If they decline, we expect there to be pretty profound ecological consequences and there may be increases in human disease burden. And so we should appreciate vultures and invest in their conservation.”

Find the full study here.