Earlier this year in my AP Biology class, I got to do an experiment on planarian worms. Planarians are flatworms that, when cut into pieces, can regenerate fully into several new worms. My class was able to do this thanks to Dr. Carolyn Adler from Cornell University, who provided the planarian worms and came to present to my class. I recently had the pleasure of speaking with her again to ask some more questions about her research and her journey through science.
Lily Wang ’26: When and how did you become interested in biology?
Dr. Carolyn Adler: I first became aware of biology when I was a kid in Hawaii, snorkeling and exploring the oceans. But I really fell in love with biology in high school, thanks to my teacher whom I had for both freshman biology and AP Biology.
LW: What’s the path that led you to where you are today?
CA: I went to a liberal arts college. My high school biology teacher encouraged me to make the most of this education and take as many classes outside of biology as I could, so I actually took the minimum number of required biology classes at my college! After I graduated, I took a job in a lab in Boston where I was working with frogs as well as cultured cells. I had to learn a lot about proteins and genes and how they work together as frogs develop.
From this experience, I fell in love with being in the lab and being surrounded by people who were really smart, thoughtful, and logical, so I decided to apply to graduate school to keep working in this kind of environment. I also really fell in love with mixing tiny quantities of clear liquids in a tube, and then seeing them do something on a gel. I love this abstraction of being able to see something that you cannot really see normally, like an enzymatic reaction or DNA being stitched together. It’s really amazing to me.
LW: How did you choose what to study for your research and what drew you to this field?
CA: When I was in graduate school, I loved working with invertebrates—small animals with no backbones—because you can do really creative experiments. For me, doing biology is this perfect blend of being a creative human and trying to figure out how the natural world works. I did my PhD studying C. elegans, which is a small nematode that’s really awesome for doing genetics. It is a clear animal, so you can do a lot of beautiful microscopy with it. My entire PhD was looking at one single cell in the worm as the worm developed.
Then when I finished my PhD, I knew I wanted to do something that was a little bit broader and had a different element of discovery in it, so I decided to work with planarians. They are also worms, but flatworms, and they had been studied in the past hundred years because of their regenerative properties. But there [is] only a very small community studying them now. I knew that if I worked with planarians, I would be getting in at the ground floor to develop the tools and resources to understand regeneration. Right now, my lab studies planarians because we think of them as essentially bags of stem cells. To my knowledge, there isn’t really another organism like that. We are trying to understand how the stem cells are able to recognize what is missing [from the worm] and how to make it.
LW: What has been your most significant finding?
CA: My research looks at how planarians can make all their organs. They have a brain, mouth, intestine, and muscle, basically all types of tissue that we have in our bodies, but a little simpler. The stem cells in the worms can make all of those different organs in an adult planarian. That is cool because in our bodies, this [the stem cells’ ability to make all different organs] is something that only happens during embryonic development; but in planarians it happens in an adult worm who has been alive for who knows how long!
I figured out how to remove one entire organ from an adult planarian and see it get rebuilt within an adult animal. This would be equivalent to me taking away your liver, and your body growing it back with a new liver working totally normally as if it were never gone. I was interested in identifying how the stem cells are able to recognize what organ has been taken away, and how the cells are instructed at a protein level to construct an entire new organ.
LW: Why is your research important?
CA: My research is important because it is very unique. Many other animals that are studied cannot regenerate to the extent that planarians can. The goal of our research is to understand the fundamental rules that govern how regeneration can happen.
LW: What are some applications of your research to organisms besides planarians?
CA: In our bodies, we have stem cells that are constantly making new cells. For example, in your intestine, there are stem cells that are rebuilding your entire intestinal lining. It is amazing that the entire inside of your intestine is completely turned over every single week. However, those stem cells are only able to make the intestinal lining. The same is true with your blood stem cells, which can only make more blood cells. This is fundamentally different from the stem cells in planarians, which can give rise to any type of cell. For example, you can take a tiny piece of the tail, and it can regenerate into an organism with a brain.
What we want in the future is to be able to live in a world where we can repair a severed spinal cord and help people with significant neural injuries with stem cells. We hope that we can use planarians to learn how the stem cells are able to recognize what is missing and how to make it.
LW: What does a typical day for you look like?
CA: Every day is different, actually. This is one of the wonderful things about being a scientist. At different stages of becoming a scientist your days change dramatically. When I was just learning how to do science, I was in the lab all day long for eight, ten, or twelve hours doing experiments, making mistakes, learning from my mistakes, and then trying again.
Now, my job is a lot more complicated with more parts. Part of my days are a mix of making sure the lab is functioning properly; taking care of our worms—we probably have one hundred thousand worms to feed—and overseeing graduate students who are moving forward projects in the lab, because they all focus on different aspects of regeneration. I also spend a lot of my day writing. We need to acquire funding for our research, and a lot of this money comes from the government. Otherwise, I’m writing papers, talking to students, and teaching. There is no day that is identical to the next one, and that is really fun.
LW: What is your favorite aspect of your job?
CA: I have two. One is being surrounded by people that are really smart, creative, and excitable. The other is working with young scientists, like undergraduates and PhD students who are just learning how to do research. It’s really exciting to see someone grow up [scientifically] in my lab, and it’s so gratifying to see them mature and go on to do really wonderful things.
LW: What are obstacles you have encountered in your career and how did you overcome them?
CA: There are so many obstacles, but I would say the biggest obstacle is believing in myself and thinking that I can continue to do this. Sometimes you are your own worst enemy, and you can talk yourself out of applying for a grant, a job, or an opportunity. Finding the confidence to push through and surrounding myself with people who can help me has been a real challenge.
LW: What is it like being a woman in STEM?
CA: I don’t know anything different! I don’t know what it’s like to be a man in STEM. There are times when I have felt excluded, for one reason or another, but I don’t know for sure if it is because I am a woman. When I was in high school and college, I was so amazed at the strength and the perseverance of the pioneering women scientists that I read about in books. I found a lot of inspiration from those role models. Since then it has always been really exciting for me to meet them or see them speak. When I hear those stories, it doesn’t necessarily resemble my own experience; but it makes me feel a tremendous obligation to continue and not give up as a scientist.
LW: What advice would you give to high school students who are interested in science?
CA: If you like science now, stick with it! Sometimes the classes that you take in high school and early in college might seem a little bit dry, but they are providing you with an essential foundation for your future. There are so many important problems to be solved through science: climate change, emerging diseases, and the possibility of finding life on other planets. These problems will require creativity and synthesis of ideas only possible through human innovation.
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