Five 91探花 researchers have been named AAAS Fellows, according to a . They are among 471 newly elected fellows from around the world, who are recognized for their 鈥渟cientifically and socially distinguished achievements鈥� in science and engineering. A tradition dating back to 1874, election as an AAAS Fellow is a lifetime honor. All fellows are expected to meet the commonly held standards of professional ethics and scientific integrity.

This year鈥檚 91探花AAAS fellows are:

, professor of genome sciences in 91探花Medicine, was recognized for her distinguished contributions to the field of the evolution of tissue development by signaling pathways and to the training of junior scientists. She studies developmental biology, and her work focuses on the patterns and shapes that appear as an organism forms into a living creature composed of a variety of cell types and organs. Her laboratory models are fruit flies, and her investigations begin in the egg chamber and the laid egg. Among her research interests are cell signals and cell migration critical to development, and the evolution of these processes. In addition, new genomic technologies are enabling her research team to manipulate the timing and location of gene activity within developing fly cells. Berg and her team also have designed a system to obtain live imaging of some of the developmental events that take place. Among Berg鈥檚 overarching goals is to better understand the genetic and molecular dysfunctions that lead to prenatal malformations and other disorders. The hope, Berg says, is that basic research, over the long term, might lead to clinical diagnostics for risk factors and to evaluation of potential treatments. Berg鈥檚 course topics are wide-ranging, and include introductory biology, biomedical ethics and forensic genetics at crime scenes.

, the David R. M. Scott Endowed Professor in Forest Resources and professor of plant microbiology in the 91探花School of Environmental and Forest Sciences, was recognized for distinguished contributions to unraveling mechanisms by which microbes colonize plants, increase plant growth and yields in nutrient-limited conditions, increase water use efficiency and drought tolerance, and improve plant health. Her research is on the importance of the plant microbiome as a resource for nature-based solutions to environmental challenges including pollution, climate change and colonizing the moon. A 91探花faculty member since 2003, she has received several awards and honors including the Lockwood Endowed Professorship (2013-2021), Director鈥檚 Faculty Award for 鈥渆xemplary contributions to student mentoring鈥� and the Faculty Member of the Year award (2014). She serves on the executive teams of the International Poplar Commission (Co-Vice Chair, Environmental and Ecosystem Services) and the International Symbiosis Society (VP, Education). She holds an adjunct faculty appointment in the Department of Microbiology.

, professor of microbiology in 91探花Medicine, was recognized for his distinguished contributions to the field of microbial interactions, particularly with regard to unraveling mechanisms responsible for the formation of surface-attached communities called biofilms. Parsek explores the social biology of bacterial communities. One of his areas of investigation is quorum-sensing 鈥� how bacteria use signaling molecules to sense the presence of others of the same species. This communication system allows them to coordinate their behavior as a group. Another of his related fields of interest is biofilms. These are bacteria that produce an extracellular matrix to bind themselves together. The matrix protects the community and plays a role, for example, in resistance to antimicrobials and antibiotics and in the persistence of chronic infection. Parsek鈥檚 lab studies the composition of this matrix and how it is assembled. They are especially interested in Pseudomonas aeruginosa, which lives in several different environmental niches, but is notorious for infecting the lungs of cystic fibrosis patients and for colonizing burn wounds and growing on implanted biomaterials. In recent work his lab looked at how these bacteria can sense surfaces. A 91探花faculty member since 2011, Parsek is a member of the American Academy of Microbiology and was named a Kavli fellow by the National Academy of Sciences.

, the Lloyd and Kay Chapman Endowed Chair for Oral Health in the 91探花School of Dentistry, was recognized for translating knowledge from the behavioral and social sciences to address the causes of children鈥檚 oral health inequities. In recent years Chi has studied why some parents reject fluoride for their children and worked with Yup鈥檌k communities to improve the oral health of Alaska Native children. In 2018 he was named Pediatric Dentist of the Year by the American Academy of Pediatric Dentistry, and in 2025 he received the Presidential Early Career Award for Scientists and Engineers (PECASE) from President Joe Biden. A member of the 91探花faculty since 2010, Chi is also the associate dean for research in the School of Dentistry and a professor of health systems and population health in the 91探花School of Public Health. He is editor-in-chief the International Journal of Paediatric Dentistry and treats patients at the Odessa Brown Children鈥檚 Clinic in Seattle.

, the Larry R. Dalton Endowed Chair in Chemistry and associate dean for research in the College of Arts & Sciences, is honored for his contributions to the development and application of time-dependent quantum theory and relativistic electronic structure theory, and for advancing educational pathways and diversity in STEM. Li conducts research at the intersection of physics, chemistry, materials science, mathematics and scientific computing, and he has developed widely used computational software. A 91探花faculty member since 2005, Li’s honors include a Sloan Research Fellowship, the NSF CAREER Award, the American Chemical Society Jack Simons Award in Theoretical Physical Chemistry and the 91探花Distinguished Teaching Award. He is a fellow of the American Physical Society (APS) and the Royal Society of Chemistry (RSC), a Lab Fellow at Pacific Northwest National Laboratory and an elected member of the Washington State Academy of Sciences.

Bacteria may draw other bacteria to a site of infection by laying down trails of a 鈥渕olecular glue鈥� that lead free-swimming individuals to come together and organize into colonies.

In the study, researchers were looking at how a species of bacteria called Pseudomonas aeruginosa attach and move about on surfaces. P. aeruginosa is a common cause of serious, often difficult-to-treat infections.

One reason they are so difficult to treat is their ability to mass together and surround themselves with matrix of proteins, DNA and polysaccharides, called a biofilm, that protects them from antibiotics and the body鈥檚 immune attack.

The study was the result of a collaboration of researchers from the University of California, Los Angeles, the 91探花 in Seattle, and Northwestern University in Evanston, Illinois.

The findings were published May 8 in Nature in a titled, “Psl trails guide exploration and microcolony formation in Pseudomonas aeruginosa biofilms.”

Kun Zhao. from the UCLA Department of Bioengineering and Boo Shan Tseng from the 91探花Department of Microbiology are the paper鈥檚 lead authors. The senior authors are Gerald C. L. Wong, professor of bioengineering at the California Nanosystems Institute at UCLA;聽 Matthew R. Parsek,聽 UW聽 professor of microbiology, and Erik Luitjen, at Northwestern University.

In earlier studies, the researchers had noticed that when individual, free-swimming P. aeruginosa attached themselves to glass and began to crawl along the surface they left a trail of a polysaccharide called Psl.

鈥淭his was surprising because in the bacterial world this is somewhat unusual,鈥� said Parsek,. 鈥淎nd it looked cool. But the question was whether it was biologically important.鈥�

For this study, the researchers used a specially designed chamber that allowed them to watch how free-swimming P. aeruginosa attached to and moved about on a glass surface. They then used video microscopy to track and analyze the behavior the bacteria.

鈥淪ome of the bacteria remained fixed in position,鈥� said Parsek. 鈥淏ut some moved around on the surface, apparently randomly but leaving a trail that influenced the surface behavior of other bacteria that encountered it.鈥�

Once enough of the bacteria had gathered, about 50 or so, their behavior changed: they abandoned their wandering ways and began to organize into small structures called micro-colonies, the first step in biofilm formation.

If there are ways to inhibit the formation of these trails or block their effect, it may be possible to inhibit the formation of biofilms, Parsek said. This might help prevent infections or make them easier to treat.

The researchers are also interested to learn whether other bacterial species also take these polysaccharide trails as a signal to congregate. Pseudomonas infections often involve other bacterial species and this might explain how these polymicrobial infections get started.

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The 91探花portion of the study was supported by National Institutes of Health grants R01HL087920, R01AI077628, R01AI081983, R56AI061396 and National Science Foundation grant MCB0822405.