It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Tuesday, July 15, 2025
Pavlov’s dogs were conditioned to go to their treat. Why do some animals learn to interact with the bell instead?
High school students learn that Pavlov’s dogs were conditioned to associate the sound of a bell with getting food. The association was so strong that the dogs would begin to salivate when they heard the bell, before there was even a whiff of food. When they were finally presented with the food, they ate it.
They did not lick the bell.
But that’s just what some animals will do when presented with a stimulus, or cue, that has been paired with a reward: interact with the cue. Sometimes they’ll paw at it and even gnaw at it, said Sara Morrison, research assistant professor in the Department of Neuroscience at Pitt’s Kenneth P. Dietrich School of Arts and Sciences. Only once the reward has been delivered will they turn their attention to that tasty sugar pellet.
Animals who display this behavior are known as sign trackers. Alternatively, goal trackers head toward the area where they expect their reward to be delivered. A study from Morrison’s lab, published in the Journal of Neuroscience on June 25, found that sign tracking is an altogether different learning process than goal tracking.
The research showed that in rats, sign trackers, learning to value a cue relies on the availability of the neurotransmitter dopamine in a particular brain region at the time they receive their reward. Neither inhibiting nor increasing dopamine had any effect on goal trackers, Morrison said, a finding contrary to the way researchers have historically thought of cue-reward associations: as dopamine-dependent. While that seems to be the case for sign trackers, Morrison’s research indicates goal tracking is reliant on a different, non-dopamine-dependent learning mechanism.
A better understanding of the neurological basis of sign tracking, and how to unlearn it, may help researchers better understand risk factors for related psychiatric disorders.
Sign tracking has been linked to risk-taking, impulsivity and substance abuse relapse. And it’s “sticky” — even after a reward is taken away, sign trackers are more likely to react to a cue than goal trackers. Even if the reward is switched to something the animals aren’t interested in, sign trackers continue to react to the cue.
The research team, led by first author Ethan Herring (A&S ’23), used rats engineered with dopamine neurons that could be turned on and off using light, a method known as optogenetics, in the brain’s ventral tegmental area. The team could inhibit or increase the release of dopamine at will.
After giving rats the 8-second cue that they had been conditioned to associate with sugar pellets, the researchers turned off dopamine neurons at the time the reward was delivered. “Inhibiting dopamine prevented the rats from learning to sign track,” Morrison said. “When we stopped the inhibition, after a few days some went on to become sign trackers again.”
Adding additional dopamine when rats received the reward, however, did not help sign trackers learn the association any faster. And when the additional stimulation was taken away, the rats stopped developing sign-tracking abilities for a few days.
“This says something really cool,” Morris said. “The signal seemed to scale to the amount of dopamine provided. It was like we were giving a bigger reward, then took half of that away.” The rats reacted as if the higher dopamine output was their baseline for a few days, after which they again began to improve as sign trackers.
That response makes sense, according to Morrison. “We all learn equally well from all different kinds of rewards. There must be some way our brain scales the rewards to the appropriate learning rate.”
A team that includes Rutgers University-New Brunswick scientists has unlocked some of the secrets of corn DNA, revealing how specific sections of genetic material control vital traits such as plant architecture and pest resistance.
The discovery could enable scientists to use new technologies to improve corn, making it more resilient and productive, the scientists said.
In a report in the science journal Nature Plants, researchers described finding where certain proteins called transcription factors attach to the DNA in corn plants and how this sticking changes how genes are turned on or off in a particular tissue. They looked at two lines of corn and found big differences at these spots in the DNA sequence, which they said could help explain why the plants look and act differently.
“In this work, we discovered where transcription factors are binding in the genome and therefore influencing the expression of maize [corn] genes,” said Andrea Gallavotti, a professor at the Waksman Institute of Microbiology and an author of the study. “Importantly, we did this analysis in two distinct maize [corn] lines that are different for many traits, including resistance to disease and architecture.”
In North America, “corn” and “maize” refer to the same cereal grain. However, “maize” is the more internationally recognized and scientifically preferred term, said Gallavotti, also a professor in the Department of Plant Biology in the Rutgers School of Environmental and Biological Sciences.
Corn or maize touches many aspects of daily life worldwide. It is a staple food for many cultures around the world and is rich in carbohydrates, fiber, vitamins and minerals. It also has major industrial applications -- used as livestock feed, for the production of biodegradable plastics, adhesives and textiles, and to produce ethanol.
The research is a collaborative effort between Rutgers and New York University scientists, led by Shao-shan Carol Huang, and other institutions, who are focused on tackling inquiries into the extremely complex and large maize genome. This partnership has been instrumental in advancing their understanding of what regulates when and where genes are turned on and off in maize, Gallavotti said.
The team started by looking to achieve a better understanding of how transcription factors modulate maize genes, adjusting, regulating or controlling their level of activity. Sifting through vast amounts of bioinformatic data, they created a map of the binding sites of transcription factors in the maize genome. The transcription factors affix themselves to special parts of the maize plant’s DNA called cis-regulatory regions.
Once the researchers had this information, they were able to compare these binding sites across different maize lines to understand variations. The team contrasted two different types of maize plants, B73 and Mo17, in the study.
“We found that there are big differences in where transcription factors bind and in the organization of these cis-regulatory regions in the two types of maize,” Gallavotti said. “These differences affect gene expression, and the resulting traits are an important source of variation in maize.”
Using an extremely precise biological tool known as CRISPR-Cas9, the team edited some of these DNA regions and studied the effects of the changes on the plant, including on a gene regulating resistance to ear worms.
CRISPR stands for clustered regularly interspaced short palindromic repeats. It is a natural defense mechanism found in bacteria, used to protect themselves from viruses. Scientists have adapted this system for use in gene editing.
The system involves two key components. CRISPR RNA is a molecule that guides the system to the specific DNA sequence that needs to be edited. Cas9 is an enzyme or protein that acts like molecular scissors to cut the DNA at the targeted location.
“Variation in these cis-regulatory regions was crucial for the domestication and improvement of many crops,” Gallavotti said. “Today, technologies like CRISPR-Cas9 allow us to introduce changes in certain traits, and cis-regulatory regions are important targets for these changes.”
Until now, the challenge for scientists has been to figure out what to target.
“Our analysis helps map and study these regions, which can be used to improve crop species,” Gallavotti said. “We hope this resource can be used to target particular regions for any trait. It could be resistance to stress, resistance to pests, modification of the architecture of a plant.”
Rutgers researchers at the Waksman Institute of Microbiology who contributed to the study included Mary Galli, the main author of this study, Zongliang Chen, Amina Chaudhry, Jason Gregory and Fan Feng. This research was mainly supported by grants from the National Science Foundation and the National Institutes of Health.
Warming ocean temperatures are causing a phenomenon called coral bleaching, putting corals at a greater risk of starvation, disease and death.
This study shows that rice coral, an important reef-building species, passes on thermal resistance to their offspring and avoids coral bleaching. Understanding this is important to building healthier coral reefs and protecting their future.
Coral reefs are habitats for nearly a quarter of all marine life, protect coasts from erosion and support the livelihoods of millions. Protecting coral reefs is crucial to preserving the future of our oceans.
EAST LANSING, Mich. — Plunge into the shallows off the Florida Keys, Hawaiʻi or the Great Barrier Reef in Australia and you are likely to meet a startling sight.
Where there were once acres of dazzling coral — an underwater world of dayglo greens, brassy yellows and midnight blues — is now a ghostly landscape, with many reefs seemingly drained of their pigment.
Caused by stressful conditions like warming ocean temperatures, coral bleaching is a leading threat to some of our planet’s most diverse and vital ecosystems.
Now, a team of researchers has found that some corals survive warming ocean temperatures by passing heat-resisting abilities on to their offspring.
The findings, published in the journal NatureCommunications, are the result of a collaboration between Michigan State University, Duke University and the Hawaiʻi Institute of Marine Biology, or HIMB, at the University of Hawaiʻi at Mānoa. This work, funded by the National Science Foundation and a Michigan State University Climate Change Research grant, is crucial in the race to better conserve and restore threatened reefs across the globe.
Coral reefs are habitats for nearly a quarter of all marine life, protecting coastlines from storms and erosion and supporting the livelihoods of millions of people around the world. Though still alive, bleached corals are at a much higher risk of disease, starvation and eventual mortality.
In their latest study, the team explored how resistance to thermal stress is passed down from parent to offspring in an important reef-building species known as rice coral. These findings are helping researchers breed stronger, heat-tolerant generations to better face environmental stress.
“The Coral Resilience Lab in Hawaiʻi has developed amazing methods to breed and rear corals during natural summer spawning,” said Spartan biochemist and study co-author Rob Quinn, whose lab takes samples of these corals and generates massive datasets on their biochemistry with instruments at MSU.
“This is a true scientific collaboration that can support coral breeding and reproduction to cultivate more resilient corals for the warming oceans of the future.”
A colorful crowd
The kaleidoscopic of shades we associate with healthy coral is the product of a bustling exchange of resources between a coral animal and its algae partners.
When all is well, you might think of this relationship as that of tenants living in a home and paying a bit of rent.
In exchange for cozy, sheltered spaces found within the coral tissue as well as nutrients, algae use photosynthesis to produce sugars. These sugars can provide up to 95% of the energy that coral needs to grow and form the sprawling, breathtaking reefs we know.
In tropical waters often lacking nutrients, disruptions in this exchange — like those that occur during bleaching events — can be disastrous.
When looking at a specimen of coral that’s suffered bleaching, you’re glimpsing a coral that’s “kicked out” its algae, leaving behind a pale skeleton.
“Corals are like the trees in an old growth forest; they build the ecosystems we know as reefs on the energetic foundation between the animal and algae,” explained Crawford Drury, an assistant researcher at the Coral Resilience Lab at HIMB and co-author of the study.
In the waters of Kāneʻohe Bay, the Coral Resilience Lab is spearheading research to best understand this coral reef ecology and the molecular mechanisms driving thermal stress.
The lab is likewise pioneering the breeding of thermally resistant coral for experiments and the restoration of reefs, a highly specialized process few labs in the world can achieve.
So, while you’d usually be hard pressed to find fresh coral for study in East Lansing, MSU’s partnership with the Coral Resilience Lab has led to a globe-spanning collaboration that closes the gap between field and laboratory.
“HIMB and MSU have developed a really amazing partnership. I’m just happy they’ve let me be a part of it. I can’t wait to see what comes out of it next,” said Ty Roach, a visiting faculty at Duke University and lead author of the new study.
Heat-resistant hand-me-downs
In the wild, rice coral takes on a dizzying array of shapes, from jutting, spiky protrusions to flat, tiered terraces — all identifiable by the tiny grain-like projections that lend the species its name.
When samples arrive at MSU, Quinn applies an analytical approach known as metabolomics to understand the complex biochemistry of the organisms.
Like a snapshot of life in motion, metabolomics allows researchers to get an idea of what’s occurring within a cell or tissue sample at a precise moment in time.
Leveraging advanced instrumentation found in MSU’s Mass Spectrometry and Metabolomics Core, the team searched for biochemical signatures associated with bleaching resistance in their samples.
This included analyzing coral sperm, eggs, embryos and larvae, as well as their algal “collaborators.”
Through their analyses, the researchers discovered that both coral and algae pass along the biochemical signature of thermal tolerance, and that this tolerance was successfully maintained from parent coral into the next generation.
Given rice coral’s method of reproduction and the numerous stages of the coral life cycle, this was an impressive feat.
“Corals usually spawn based on the lunar cycle; for our experiment, this means late nights around the summer new moons and months of work rearing coral larvae and juveniles,” said Drury.
This summer, Quinn group graduate student Sarah VanDiepenbos had the chance to join Coral Resilience Lab researchers to witness one such nighttime coral spawning and breeding event.
“It was such a serene, beautiful experience. The timing is impeccable, as the process only lasts 20 to 30 minutes total,” VanDiepenbos explained.
“The coral bundles slowly float upward, trying to find another gamete to combine with once they get to the surface. This release is gradual, so they can have a maximum chance of finding spawn from a different coral,” she added.
Tougher genes for warmer seas
While many species of corals uptake symbionts from the surrounding seawater, rice coral provide their eggs with algae, handing this relationship down from parent to child.
“To have this algae’s thermal tolerance remain through an entire generation and all the stages of coral development, that’s surprising, and promising for the future of coral reefs,” Quinn said, who’s also an associate professor in MSU’s Department of Biochemistry and Molecular Biology.
Especially compelling was the fact that the earliest stages of the coral lifecycle, like embryos and larva, showed chemical signatures linked to whether parent organisms were thermally tolerant or not.
This means that not only do offspring receive heat-resistant genes, but also beneficial molecules to give them a head start against heat stress.
“Some of the most interesting findings from this work is that coral lipid biochemistry is maintained through all stages of development during reproduction,” Quinn said.
“Importantly, these lipids come from both the host coral and its algal symbiont, indicating there is crosstalk between them to prepare the next generation to resist bleaching,” he added.
In showing how inherited thermal resistance originates from both coral and algae, this research provides deeper insight into the finely tuned, symbiotic microcosm found in corals across the world’s oceans.
Most exciting for the team is how these findings are contributing to the science behind the restoration of reefs and the breeding of stronger, more heat-tolerant coral generations.
“Our metabolomics research at MSU could support reef restoration efforts at places like the Kāneʻohe Bay by identifying corals that are resistant to bleaching,” Quinn said.
By Connor Yeck
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Michigan State University has been advancing the common good with uncommon will for 170 years. One of the world’s leading public research universities, MSU pushes the boundaries of discovery to make a better, safer, healthier world for all while providing life-changing opportunities to a diverse and inclusive academic community through more than 400 programs of study in 17 degree-granting colleges.
For generations, Spartans have been changing the world through research. Federal funding helps power many of the discoveries that improve lives and keep America at the forefront of innovation and competitiveness. From lifesaving cancer treatments to solutions that advance technology, agriculture, energy and more, MSU researchers work every day to shape a better future for the people of Michigan and beyond. Learn more about MSU’s research impact powered by partnership with the federal government.
URBANA, Ill. – Gaining a better understanding of how romantic relationships develop over time is key to helping couples maintain a satisfying union and overcome challenges. Researchers and practitioners rely on theories to provide insights, and it’s important that they are accurate and reliable. A new paper from the University of Illinois Urbana-Champaign discusses how contemporary methodologies can be applied to common relationship theories in a more rigorous way.
“How relationships change influences relational, individual, and broader family functioning,” said lead author Jeremy Kanter, associate professor in the Department of Human Development and Family Studies at Illinois. “If we can refine and strengthen existing theories, we can move the field forward and help support relationship interventions for couples.”
To study relationship development, such as how relationship satisfaction changes over time, scholars often use Group-Based Trajectory Modeling (GBTM) in their studies. This approach groups individuals whose relationships change in a similar fashion across time together, facilitating a deeper understanding of the most common change patterns as relationships progress. For example, this approach has helped highlight that declines in marital satisfaction are not inevitable for most couples.
Kanter and his colleagues suggest employing GBTM to more rigorously test relationship science theories. They provide examples of refutable hypotheses when using GBTM approaches that reflect core concepts in those theories and can be used to test their relevance and accuracy in empirical studies.
The researchers discuss five popular relationship theories:
Enduring dynamics: A couple’s experiences during courtship will largely determine how their relationship develops. Those who start out with high levels of relationship functioning will likely maintain these high levels over time, while couples that start out with lower levels will remain so, indicating a pattern of stability throughout a relationship.
Emergent distress: Most couples are relatively satisfied early in their union, but some couples will experience increased negativity and hostility over time, which can be detrimental to the relationship.
Gradual disillusionment: Some couples who have very high levels of initial satisfaction will have unrealistic expectations of their partner and eventually experience disappointment and disillusionment, leading to declining relationship quality over time.
Vulnerability-stress-adaptation: Individual characteristics, stressful events, and couples’ interaction patterns combine to influence relationship quality. As a result, most couples begin their union relatively satisfied, and changes in satisfaction depend on the broader context surrounding the couple.
Relational turbulence: Couples tend to be the most vulnerable during transitional periods when partners are adapting to new roles and routines. Couples that struggle during these transitions may feel that the relationship is turbulent, resulting in later relational distress.
“These different theories are going to have different foci of intervention — whether we should focus on supporting couples when they are dating, as newlyweds, or before a transition happens,” Kanter said.
Each theory also leads to a different set of hypotheses. For example, the enduring dynamics theory would predict significant differences between couples initially and stable satisfaction over time. The emergent distress model, in contrast, would predict initial similarities among couples, but significant differences in changes over time.
“In the past years, we’ve had rapid advancements in methodology. Many of our theories were developed before we had the sophisticated tools to collect and analyze data that we do now. We want to ensure we're bringing our theories along as those innovations are happening within the research field,” he said.
For example, it’s important to consider fluctuation patterns in relationship processes (non-linear ebbs and flows) and dyadic patterns (how each partner’s changes affect the other) for a more comprehensive understanding of relationship development, Kanter noted.
“Perhaps some of the theories should be modified or combined to better reflect current knowledge of relationship patterns. This will ultimately help practitioners develop recommendations for families at risk and provide suggestions for enhancing or maintaining relationship quality.”
The paper, “Using group-based trajectory modeling to test theoretically driven hypotheses about relationship development,” is published in the Journal of Family Theory & Review [10.1111/jftr.12632]. Authors include Jeremy Kanter, Christine M. Proulx, Amy J. Rauer, and H. Cailyn Ratliff.
A groundbreaking study from Michigan State University (MSU), recently published in Nature Communications, has revealed how the multidrug-resistant superfungus Candida auris uniquely reconstructs its cell wall to survive antifungal treatments. The discovery marks a significant step toward understanding and combating one of the most dangerous fungal pathogens threatening hospitalized patients worldwide.
Led by Tuo Wang, a Carl Brubaker Endowed Professor at Department of Chemistry, the research compares C. auris with its more common relative, Candida albicans. While both species share similar cell wall structures, the study shows they deploy markedly different strategies to resist echinocandins — a class of frontline antifungal drugs.
“Invasive infections by Candida species are a growing threat, especially with the rise of drug-resistant species like C. auris and complications from COVID-19-related candidiasis,” said Wang. “Our study provides high-resolution insight into how these fungi adapt to treatment.”
Using advanced solid-state nuclear magnetic resonance spectroscopy, the team found that both fungi experience stiffening of key cell wall polysaccharides—such as β-1,6-glucans and mannan sidechains—when treated with the antifungal drug caspofungin. However, while C. albicans thickens its cell wall and alters chitin and glucan dynamics in response, C. auris takes a different approach: it increases production of β-1,6-glucan to preserve its structural integrity.
The study also sheds light on the long-mysterious role of β-1,6-glucan, an underexplored component of fungal cell walls that appears to play a critical role in drug resistance. “Gene deletion and subsequent structural analysis revealed that β-1,6-glucan is directly tied to how C. auris responds to antifungal drugs like micafungin and caspofungin,” Wang explained.
The interdisciplinary research team included MSU graduate students Kalpana Singh and Malitha Dickwella Widanage, visiting scholar Yifan Xu (now entering MSU’s Chemistry PhD program), and postdoctoral associate Jayasubba Reddy Yarava.
This interdisciplinary effort was strengthened by contributions from leading microbiologists, including Dr. Frederic Lamoth’s team at Lausanne University Hospital and the University of Lausanne (Switzerland), Dr. Neil A. R. Gow of the University of Exeter (UK), and Dr. Ping Wang of Louisiana State University Health Sciences Center. The research also benefited from access to state-of-the-art instrumentation at the National High Magnetic Field Laboratory (Tallahassee, Florida), with technical support from Dr. Frederic Mentink-Vigier and Dr. Faith Scott.
Ultimately, the research not only clarifies how C. auris survives drug treatment but also offers a roadmap for designing more effective antifungal therapies in the future by targeting species-specific structural adaptations.
