Answers to submitted questions will be answered and updated hopefully on a weekly basis. I will try my hardest to answer in a timely manner. Some responses may answer multiple questions that I grouped together. Check out what other people have asked first! Your burning question might have already been answered! ---Erin

1. How did you get to where you are today? Why did you become a scientist? Is it difficult? (Mark, Kaori, Kevin, and Jazmin, Colorado; Candace, New Mexico)

I’ve always liked looking at small creatures and animals in nature, and really enjoyed biology in middle school and high school. I was never afraid to do dissections and thought they were super cool! To get where I am today, I went to UC Santa Barbara after high school and got a B.S. in Biochemistry and Molecular Biology. I got involved in research pretty early as an undergrad, in my second year. I volunteered my time during the school year, and got paid to work over the summer and during an internship program, working on various projects in a lab studying sea squirts. I discovered that I really enjoyed doing research and asking questions about cells and how organisms develop. After I graduated, I got a job in the same lab for a year as a Research Technician. During that year, I decided I wanted to go to graduate school and get my Ph.D. I was accepted into a number of schools in California and ultimately picked Stanford’s Developmental Biology program!


As a graduate student at Stanford, I have learned how to ask good scientific questions and am still constantly learning how best to answer them with experiments! Doing research is definitely difficult, and requires a lot of perseverance. It is all about pushing the boundaries of what we currently know and learning new things. Unlike during college, I do very little memorizing and studying these days; instead, I do a lot of reading about other people’s research and thinking about how my experiments and data might answer new questions. It’s super exciting!


The O'Brien lab!

2. Do you work alone or do you have partners to help you with your science? (Jan, Colorado)

I work with lots of people! In my lab, there are two other graduate students, three post-doctoral researchers, three undergraduate research assistants, and one technician. We all work on research in the lab of our Principal Investigator, Dr. Lucy O'Brien. For more information on what those roles mean and how our lab is setup, check out this blog post!

3. How long did this research take you to complete? (Jazmin, Colorado)

Right now, I have been working for almost 3 years doing research on fruit fly stem cells. Some experiments take a couple of months to plan and get data from, while others might only take a week or two. But research is an ongoing process so it is hard to put a hard number on it!


4. How do you know when you are finished with your science experiment? (Davee, Colorado)

It really depends on the experiment! Some experiments that you start are easy to decide when they are done because the results are clear. Others might need to be repeated a lot, to make sure that the result you got was real. Others might not work in the way you wanted, and so you end it because you don’t think that it will answer your question. A good experiment requires careful planning and a clear idea of what you think it will tell you when it is done. This takes lots of practice to do!​


5. Why study Fruit Flies?! Can you only do this experiment to a fruit fly? What would the human body need in order to have the same characteristics of a fruit fly? (Racahel, Colorado; Tosty, Waunuleta, Areli,New Mexico)

While you would need to change a lot of physical things for a human to have the same characteristics of a fruit fly (size, appendages, bones vs exoskeleton etc. etc.), lots of the basic elements of patterning are the same between the two. For example, genes that control top to bottom patterning are the same! For more ways fruit flies are similar to humans, check out this cool website I found!

For my research project, I am only doing experiments with fruit flies, but you can ask a lot of the same questions that I am asking about stem cells in mice or humans. Flies are actually really, really similar to people when you look at their cells and their DNA. This is one of the big reasons why we study them. “About 61 percent of known human disease genes have a recognizable match in the genetic code of fruit flies”, say NASA scientists who send fruit flies into space to study how space affects their gene expression and behavior. Did you know NASA sends flies to space!? 


6. Why are stem cells in fruit fly guts important? Why did you want to study this? What made you interested enough about fruit flies to study them? (Jasmine, Evelyn, Bridgette, Colorad)

Great questions, why should anyone care about fruit flies or their stem cells anyways? Let me break this into a few different answers.


First, like I mentioned above, fruit flies are important for research because at the DNA level they are actually very similar to humans. So many key genes that are used to pattern a organisms body, or that are used to send signals between cells, are extremely similar between flies and other organisms, including humans. In biology, a lot of experiments we do would be unethical to do in humans, so we use flies! Flies also lay a lot of eggs, and consequently make a lot more flies in a short amount of time (about 10 days), which makes it easier to do repeated experiments on them. For more fun info on why flies are so great for research click the link below the photo. 

Second, we study stem cells in a fly, as a way to understand at a basic level how stem cells work, and ultimately how they work in humans. Just like in humans, the stem cells in a fruit fly's tissues are the key to making sure that any cells that die are replaced. The stem cells respond by dividing and making new cells when the tissue needs more cells. If the gut loses its stem cells, eventually the gut gets really sick because there aren’t enough cells available to do their jobs, and the fly dies. So stem cells are essential for the fly’s health. Also, a lot of the fly genes that are important for stem cells to function are genes that are often malfunctioning in human cancers. By studying how stem cells work normally, we can learn lot about what goes wrong in cancer.


Why am I interested in fruit flies? Because they are a great organism in which to study stem cells and the decisions they make! There are lots of crazy cool ways to manipulate genes that people have developed in the fruit fly, and this makes it a really fun and creative process to try to answer lots of burning biological questions!


7. The fruit fly is really small. Is it hard to take out the gut? How long does it take to dissect out the gut? Do you have to have really steady hands? What happens if a mistake occurs? (Armando, Dominic; Xitlali, Colorado; Luis, Dallin, New Mexico)

Yes, the fly is super small! Adults are only about 3-4 millimeters long! It does take a lot of practice to get good at dissecting the gut out of the fly’s abdomen. We have to do this under a microscope with really small tweezers. Now that I have gotten good at dissecting, I can dissect a gut out of a fly in only a few minutes. And yes, you do have to have really steady hands! For someone who is affected by caffeine pretty quickly, like me, it means you have to be careful about when you decide to have a cup of coffee that day! Shaky hands is really bad for nicely dissected guts!

If I make a mistake dissecting, I usually just try again. For my experiments, I have to dissect and image a lot of guts, so I prepare ahead of time and make sure that I have a lot of flies ready. That way if I break a gut or the image comes out badly, then I have lots of others available to make up for it. If I make a big mistake during an experiment (which I have done plenty of times!), I first determine whether it will interfere with the results or my interpretation of the results. If so, then that means that I unfortunately have to start over! I try to be organized and plan ahead so that I make less mistakes!


Hematopoietic Stem Cell Lineage

Yes! The stem cells in the fly gut can decide to (1) stay a stem cell, (2) become a hormone producing cell, or (3) become a nutrient absorbing cell. Each of these decisions is controlled by different signals both outside the cell and inside the cell. These signals cause different genes to be expressed inside the stem cell, which then ‘execute’ the decision.


Stem cells in different tissues can make different numbers of decisions depending on the types of cells the stem cells are responsible for producing. For example, in humans, hematopoietic stem cells are responsible for making ALL the types of cells in your blood (see image on left). Each of these decisions is controlled by different signals coming from many different sources in the body.

8. How do stem cells make decisions? Do stem cells make different decisions? 

(Hailey, New Mexico; Enrique, Colorado)


9. Does the speed of a fruit fly’s stem cell decisions differ from other animals' stem cells, or do all stem cells make decisions at the same speed? (Xitlali, Colorado; Elaine and Nasser, New Mexico)

Great question! I would love to know the answer to this question. My guess is that different stem cells in different animals might make decisions at different speeds. Maybe this depends on how long an animal lives or how extreme an environment it lives in!

I also think that stem cells in different tissues might make decisions at different speeds. For example, in a tissue that loses a lot of cells (like the acidic environment of the stomach), stem cells might need to divide and make decisions really fast, compared to a tissue that doesn’t lose very many cells (like your bones). You can see how fast the different parts of your own body get replaced here!


10. Are you studying anything else? (Bridgette -- Colorado)

Not right now! All of my work at the moment is on this project, with the goal of getting my Ph.D.! I did used to study sea squirts when I was an undergraduate research assistant at UC Santa Barbara though!


11. Are all the fruit flies you experiment on grown in the lab? What do you feed fruit flies? (Srini, California)

Yes! I work in a lab and we grow all of our fruit flies in different incubators. These look like a refrigerator, except instead of keeping your food cold, they keep our flies at different temperatures. Flies grow best at 25C (77F), but we also can grow them at 18C (64F) or 29C (84F) depending on what experiments we are doing. We grow fruit flies in vials and bottles that have their food mixture in the bottom.


As you might imagine, fruit flies eat things that you might find in rotting fruit! Mainly different sugars and yeast. Our fly food at Stanford is a mixture of cornmeal, agar and molasses. For important crosses and experiments, we also supplement with a paste made out of bread yeast and water. Flies get a lot of protein from the yeast and love it! For more info about flies and how you or your class can culture them at home, check out this great page from the Berg lab at the University of Washington. 

One of our incubators!

Flies growing in a food vial

12. How many years of school did it take for you to get where you are today? (Tayler, Shane, Shatia, Arianna, Colten and Tina, New Mexico)

So far I have complete high school (12 years), undergraduate (4 years), and some of graduate school (4 years). So right now I have been in school for about 20 years and am in the 20th grade!


13. What did you major in and where? (Pablo, Areli and Darion, New Mexico)

In college at UC Santa Barbara, I majored in Biochemistry and Molecular Biology. Now as a graduate student at Stanford, I am in the Developmental Biology department and so you can say I am majoring in Developmental Biology and Stem Cell Biology!


14. Is there a way for preserving stem cells and then using them later to help regrow parts of a body, like an arm or a leg? (Christopher, California)

So far, human body parts have proven to be pretty difficult to regrow! While this is a bit outside my area of study, I do know that while generally we can't regrow whole body parts in humans, we can regenerate parts of our livers and tissues like our blood from stem cell transplants. This is basically how doctors treat people with bad blood cancers. Doctors are able to isolate stem cells from another person's bone marrow that are capable of producing all the different types of blood cells in your body. These cells are transplanted into the sick person who has undergone radiation therapy to kill off their cancerous and sick blood stem cells. The cells that are transplanted should then home to the bone marrow and start generating new blood cells, hopefully making the sick person better.


The same concept is true for skin grafts. Doctors can take skin cells from another part of your body and grow them in a dish to graft onto a severely burned or injured part of your body! Regrowing your arm is much more complicated than the blood because your arm is made up of so many different kinds of tissues! Muscle cells, skin cells, nerve cells, fat cells, bone cells, blood cells and more all are needed to make up an arm. Each of these tissues requires at least one of its own types of adult stem cells, and so coordinating them all together would be an immense challenge! 

What is amazing though, is that there are actually organisms that can regrow whole body parts like their legs! Check out the adorable Axolotl! They are able to regenerate their arms and legs if they are amputated. Scientists study them to try to understand how we might be able to regenerate our own body parts in the future. So far, it seems like they are able to heal wounds using a pretty different and unique mechanism from mammals.


Axolotl have the ability to regrow their limbs if they are amputated


15. How much time do you spend working with other people vs being in the lab? (Saurav, California)

These days, since I have finished all of my classwork, I mostly spend my time doing experiments in my lab. This doesn't mean that I am not working with other people simultaneously though! My lab mates are usually in lab as well, and we talk about our projects together and discuss our ideas and experiments. We also talk about other things too, like how our weekends went or funny things that happened that day with my dog!


Every week we also have lab meeting, where the people in our lab all get together and meet with our professor to share data and talk about our projects. Sometimes one person presents their latest experiments and data for the whole meeting, and sometimes we do short 15min discussions. We also usually talk about any issues that have come up in the lab that week, or learn about any talks our professor wants us to attend. Its a good time to share what you are thinking about and get other people's feedback on your ideas.


During the school year, we also will go to presentations (called seminars) by scientists from other universities who come to share their research with people at Stanford. Anyone can actually come to these talks! They are a great way to learn about new ideas from other people who study things that interest you, and stay up to date on the latest cool work coming from labs you respect!


In September, my department also has an annual retreat, where all the labs come together in Monterey, by the beach, and people present posters and powerpoint talks about their work! It is a great way to practice talking in front of people and thinking on your toes! Its also a great time to relax and get to know people a bit better, and also just enjoy the beach and good food! Science can be a very social process!

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