Cell crawling is a form of locomotion where a cell moves across a surface by repeatedly extending its front, anchoring it and then pulling its body forward. The movement is driven by the dynamic remodeling of the cell’s internal cytoskeleton, primarily involving the protein actin. In this structured illumination micrograph, a crawling cell is shown with DNA in blue and actin filaments in pink.
Image courtesy of Dylan T. Burnette, Vanderbilt University.
Collagen is a strong, ropelike molecule that forms stretch-resistant fibers. The most abundant protein in our bodies, collagen accounts for roughly one-quarter of our total protein mass. Among its many functions is giving strength to our tendons, ligaments and bones, and providing scaffolding for skin wounds to heal. There are about 20 different types of collagen, each adapted to the needs of specific tissues.
Image courtesy of Tom Deerinck, NCMIR, UCSD.
Meet one of our early-career scientists at Sanford Burnham Prebys: Alexandra Houser, PhD, a postdoctoral researcher in the lab of Shengjie Feng, PhD. Houser is a structural biologist studying ion channels to better understand how the brain works.
When and how did you become interested in science?
A family friend of ours was a scientist. When I was younger, she would take me to the woods near where my dad worked as a mechanic to look for owl pellets and put the tiny skeletons inside the pellets back together.
When I ended up going to community college, I found the science courses were the most interesting. I earned my associate’s degree in biology and then transferred to a university.
What did you imagine you would be doing professionally, and how did it evolve?
I am always in awe of people that knew what they wanted to do their entire lives because I had no idea.
I remember back when I didn’t even know that research happened on university campuses. I was really surprised when people told me I could go work in a lab. I remember asking what class to sign up for and they said I could just go talk to a scientist if I was interested in what they were doing.
Soon after that, I started working in a lab on motor proteins such as kinesin, which I found fascinating. When I was getting closer to graduating with my bachelor’s degree, my mentor said I had a lot of potential as a scientist and that I should go to graduate school.
I told her that I couldn’t afford grad school, and she told me about tuition remission and getting paid a living stipend. I thought, “Oh, my god, I have to do this!”
Over time, I’ve gotten more and more into biochemistry, and now I’m here working as a biochemist.
What brought you to the Feng lab at Sanford Burnham Prebys?
I learned about her research because we were working in similar fields. In grad school, I worked on sodium ion channels. Shengjie works on potassium ion channels.
I used to host an ion channel journal club in graduate school. I gave a presentation on one of her papers and loved it and then saw that she was starting a lab.
Sodium and potassium ion channels play a big role in the brain. What generates the electrical signal is the difference between sodium and potassium inside and outside the cell. It’s the balance of those two ion channels that turn neurons on or off.
In graduate school, I basically looked at how neurons turn on through sodium ion channels, and now I’m looking at how they turn off via potassium ion channels.
What are the key areas of research you focus on?
Someone once told me that some people prefer areas of science that are broad in scope and where you have to make more generalized assumptions, and others like areas of science where you can unequivocally determine if something is this or that.
I am in the unequivocally this or that camp. I do what I like to call protein selfies. When you take a selfie, you take a bunch of pictures and pick the best one. With a protein selfie, I take more than a bunch. A few million more.
Because proteins are so small, I need to average these millions of pictures together to see what it looks like. And then with an image of the structure, we can get ideas of what the protein does and how.
What motivates you about your research?
I’ve worked a lot of jobs in my life, but this feels different. Sometimes I just stay late because I’m excited and it’s fun. I may be seeing something for the first time that no one else has ever seen.
When you’re doing basic research, sometimes you just find really cool stuff!
What do you like about working here?
I love the support that’s here for postdoctoral researchers. Honestly, it’s been almost universally positive. I don’t think that is true everywhere.
The postdoc community here is so active organizing standout events such as family day and holiday gatherings. We have tremendous opportunities for workshops and industry tours.
I’ve also enjoyed events put on by the Workforce Engagement & Belonging team, especially this summer’s book club. It was great getting to meet people from administrative offices and other labs, all the different people that make up Sanford Burnham Prebys.
How do you hope your work will advance science and/or improve health?
As a basic scientist, I feel like my research will help other researchers make an impact in the future.
I’m doing everything I can to explain a protein’s structure and how it influences function. I imagine someone years from now will use my science to develop a new drug for this protein target. My work can help them understand areas where a drug could bind the protein, for example.
What are your hopes for the next stage in your career?
I’d really like to go into industry. It often goes that the more successful you are as a principal investigator, the less time you can spend at the laboratory bench conducting experiments.
And I love being at the bench.
Have you had an influential mentor?
My undergraduate mentor made a major difference in my career. I had a lot to learn. I didn’t know anything about academic science. He was really good at pushing me but also giving me room to fail.
He taught me so many things that I use all the time, such as how to focus on the big picture of your science. In structural biology, you can analyze your data for five years. Understanding your big question helps you know when you’ve reached the resolution needed to answer this question. Then you can move forward with the next question.
What do you enjoy doing when you’re not in the lab?
I’m a big reader. I read books all the time. My fellow lab members make fun of me because even when I’m eating lunch, I’m always there with my books.
I also like cooking dinner together with friends and going to the beach with my son and my dog.
Postdocs at Sanford Burnham Prebys are pushing the boundaries of science every day through curiosity, collaboration, and innovation. This series highlights their unique journeys, what inspires their work, and the impact they’re making across our labs.
A growing Vibrio cholerae biofilm. Cholera bacteria form colonies called biofilms that enable them to resist antibiotic therapy within the body and other challenges to their growth. Each slightly curved comma shape represents an individual bacterium from assembled confocal microscopy images. Different colors show each bacterium’s position in the biofilm in relation to the surface on which the film is growing.
Image courtesy of Jing Yan and Bonnie Bassler, Princeton University.
Basic research is sometimes mocked or misunderstood because its ultimate value to human society may not be obvious. Most modern advances in medicine, science and technology originated with basic research that created new knowledge and laid the path to greater health and prosperity.
In the October 29 issue of Nature, the journal celebrates “7 basic science discoveries that changed the world.” Among them, the discovery of a heat-loving bacterium named Thermus aquaticus in a Yellowstone National Park hot spring by microbiologist Thomas Brock (1926-2021) and his undergrad assistant Hudson Freeze, PhD, now director of the Sanford Children’s Health Research Center at Sanford Burnham Prebys.
“I was seeing something that nobody had ever seen before,” Freeze told the journal. “I still get goosebumps when I remember looking into the microscope.”
The discovery of T. aquaticus in 1966 and the isolation of a key bacterial enzyme by Brock and Freeze began the scientific journey that led to the development of the polymerase chain reaction or PCR, a method for rapidly making thousands of copies of a single fragment of DNA.
PCR has since proven to be an indispensable and ubiquitous tool throughout biomedical research and medicine.
The extracellular matrix (ECM) is a network of proteins and carbohydrates that surrounds and supports cells in tissues throughout the body. In this image, the ECM (pink) is present between the axons of nerve cells. Blue-colored nerve cell axons are surrounded by brown-colored, myelin-supplying Schwann cells, which act like insulation to help speed the transmission of electric nerve impulses down the axon. The tiny brown spots within the ECM are collagen fibers.
Image courtesy of Tom Deerinck, NCMIR, UCSD.
Feng lab member Alexandra Houser impressed the judges with her pitch on the importance of turning off brain cells
Turning off neurons in our brain is just as important as turning them on, according to third-place Postdoc Pitch Competition contestant Alexandra Houser, PhD.
Houser, a postdoctoral associate at Sanford Burnham Prebys Medical Discovery Institute in the Feng lab, discussed how our ability to have complex thoughts is due to a sequence of on and off signals—akin to a version of Morse code—that neurons use to communicate to one another. She studies proteins called voltage-gated potassium channels that are an important facilitator of these neuron-to-neuron interactions.
Better understanding of the structure of these proteins—and how it changes in aging or in diseases such as epilepsy—may help future scientists develop new treatments.
Joining Houser at the contest was fellow Sanford Burnham Prebys scientist Jessica Proulx, PhD, a postdoctoral associate in the Adams lab. She presented her work regarding how aging interferes with the harmonious balance of transcription factors and chromatin regulators that control which genes are turned on or off in different types of cells.
Proulx shared the team’s success in restoring the activity of a master transcriptional regulator of liver cell identity—HNF4 alpha—using viral-mediated gene delivery tools. This approach may underpin future treatments for age-associated liver dysfunction.
Houser and Proulx were selected to participate in the inaugural Mesa-wide Postdoc Pitch Competition held at Sanford Burnham Prebys on October 23, 2025, after being named the two best presenters at the qualifying event for the institute’s postdoctoral researchers on September 30.
Jessica Proulx, PhD, a postdoctoral associate in the Adams lab at Sanford Burnham Prebys. Image credit: Sanford Burnham Prebys.
The Postdoc Pitch Competition was hosted by the Torrey Pines Training Consortium and sponsored by local companies Yamay Bio, BD, Complete Genomics, Hamilton, TriLink Biotechnologies and Wilson Sonsini. The event featured scientists from Sanford Burnham Prebys, Scripps Research, the Salk Institute and the University of California San Diego. Participants were asked to present their work in a compelling, accessible and engaging pitch—and in three minutes or less.
Additional 2025 Postdoc Pitch Competition contestants
Event recording now available for panel discussion with scientists held on October 14, 2025
David A. Brenner, MD, president and CEO of Sanford Burnham Prebys Medical Discovery Institute, welcomed members of the San Diego community to the latest event in the “A Conversation About” community engagement program on October 14, 2025.
Attendees participated in an engaging afternoon exploring the connections between aging and metabolic disorders. Brenner moderated the discussion among three featured panelists:
The event was introduced by Reena Horowitz, founder of Group of 12 and Friends at Sanford Burnham Prebys, whose support has been instrumental in fostering dialogue around science and health within our community.
The “A Conversation About” series brings together Sanford Burnham Prebys researchers, clinicians, and community members to explore how aging influences key health issues that affect older adults. Each session highlights current findings, innovative collaborations, and opportunities to translate scientific discoveries into improved health outcomes.
Previous events included:
In this stained fluorescence image of a slice of mouse brain, green depicts the excitatory hippocampal neurons; in red are obesity-associated proteins and cell nuclei in blue.
Image courtesy of Ainara Pintor.
Dubbed “Pollock’s Glia,” this 3D reconstructed immunostained micrograph depicts astrocytes (white), oligodendrocytes (blue) and microglia (red) in human brain white matter, reminiscent of the artist Jackson Pollock’s abstract paintings.
Image courtesy of Yixun Su.