Season 3, Ep. 1

Yamilex Acevedo-Sánchez: It never really even crossed my mind, the possibility of becoming a scientist. I didn’t really have a proper exposure to biology specifically until I reached college. And that’s when I was like, wow, this is amazing.

[“Something Elated” begins]

Raleigh McElvery: Welcome to Season 3 of BioGenesis, where we get to know a biologist, where they came from, and where they’re going next. I’m Raleigh McElvery from the MIT Department of Biology —

[“Something Elated” fades out]

Conor Gearin: And I’m Conor Gearin from Whitehead Institute.

McElvery: This season, we’ll introduce you to three graduate students who are “Breaking the Mold.”

Gearin: Over the course of their research training, these biologists have shattered the pre-conceived notions they grew up with about what scientists look like and where scientists come from.

McElvery: Today, you’ll meet Yamilex Acevedo-Sánchez.

Conor: Her first exposure to science was through TV. But she’s since learned that the media often showcases a narrow swath of the faces behind the discoveries.

McElvery: Now a scientist herself, she’s seen firsthand the diversity of disciplines and brainpower that fuels the research community. Her own research project explores how deleterious pathogens sneak from one cell to the next, spurring infection.

[“Two Pound” begins]

Acevedo-Sánchez: My name is Yamilex Acevedo-Sánchez, but I go by Yami because it’s easier to pronounce. I am a third-year graduate student in the Biology Department and I’m in the Lamason lab. I was born in Philly. Both my mom and my dad met in Philly, they met while they were dancing. And I think that’s why I love dancing so much. And they had me. And then when I was three years old, they moved back to Puerto Rico.

My formation was heavily influenced by Puerto Rico because my parents aren’t fluent in English and they’re Puerto Rican. So everything that was done in the household was definitely influenced by Puerto Rican culture.

My dad didn’t finish high school. He actually dropped out when he was in eighth grade. At the time, my mom only had her high school diploma, but like both of them always encouraged me to pursue higher education just because that was something that they didn’t really have at the time. And later on, when I was, I think, like 12 or 13, my mom finished her bachelor’s in education. So she’s a teacher now.

[“Two Pound” fades out]

I always got really good grades because, like, my mom was very strict with that, like I could not go with a bad grade to my house. She really doesn’t understand what I do, but she’s always encouraged me to pursue my dreams.

McElvery: Academically, Yami’s childhood was a flurry of reading, math, and science competitions. Above all, though, she enjoyed astronomy.

[“Louver” begins]

Acevedo-Sánchez: Something I would always love to do, which is something I can’t do here, was sit outside at night with my dad and watch the stars. I remember a black chalkboard, and I would always teach the same lesson on astronomy to my toys, because I had like an encyclopedia, a Mickey Mouse encyclopedia.

I would always watch documentaries on the History Channel about space. And then my dad loves animals because he grew up on a farm, basically. And so we would always watch Animal Planet and just, I don’t know, see the people narrating, how the animals behaved. and all these things.

Gearin: The scientists in these TV shows were the first researchers Yami encountered.

Acevedo-Sánchez: My idea of a scientist was male, white, old — a very common stereotype, I think. I’m a woman first and foremost. I’m brown. I’m not old, yet. And so it never really even crossed my mind, the possibility of becoming a scientist.

[“Louvre” fades out]

Going to college was just a big achievement in itself. I didn’t even think much about what I wanted to be. I just needed to pick an institution. And that was really hard, because in addition to not having people in my family — or like friends or friends of friends that were scientists — I really didn’t know much about what was a school that could provide me with the tools I needed to be successful.

McElvery: Luckily Yami’s high school counselor —

Acevedo-Sánchez: Peña, Luz Peña —

McElvery: Pointed Yami towards her own alma mater, the University of Puerto Rico in Mayaguez.

Acevedo-Sánchez: It was between really two schools, and Peña helped me narrow it down to Mayaguez.

Gearin: But picking a college and getting accepted was just the first hurdle.

[“Friction Model” begins]

Acevedo-Sánchez: I didn’t have any savings. Because I was a student, I didn’t work. I was fully focused on college and my parents really lived — still live — bill to bill. So they didn’t have any savings for me to go to college.

Luckily, because I had good grades, the town where I went to high school, they give money to students. But I remember that first semester was really, really rough because the financial aid wasn’t enough and I didn’t even have enough money for my last rent payment of the year. And what saved me was that I have an uncle who’s better off economically than me and my family. And without even me asking, he gave me money and it was enough to pay the rent. So yeah, it was really rough. But I’ve always had people who have helped me.

[“Friction Model” fades out]

Gearin: Yami began at UPR in 2013, intending to become a cardiologist.

Acevedo-Sánchez: I was interested in becoming a physician because my dad had heart problems. And that changed like six months in. I was definitely sure that was not something I wanted to do.

McElvery: Her interest in fundamental biology started where most things do: at the level of DNA.

[“Mercurial Vision” begins]

Acevedo-Sánchez: Yeah, it was Intro to Biology, which sounds very simple, but to me it was everything. Before going to college, I knew DNA was the thing — I knew DNA was what determined who you were and what distinguished us from everyone and every living thing. But I really didn’t understand what that meant.

McElvery: She quickly switched from the pre-med track to a major in industrial microbiology.

[“Mercurial Vision” fades out]

Acevedo-Sánchez: But then it was a thing of like, OK, you don’t want to be a physician, which has always been the plan. How are you going to tell your family and what are you going to do? And that’s when my professor — my Intro Bio professor, another one of my mentors who’s helped me a lot more than I think she knows, Dr. Navas — she would always talk to freshmen about internships and different research going on in UPR from different professors. And she would always encourage us to seek out those opportunities.

At the end of my first year, I applied to one internship, didn’t get in. And then my second year,  I actually reached out to a bunch of professors and was turned down by one. And he was very mean about it, I remember. And one thing he said was, you know, like, my students end up in, like, top tier institutions. And I need to make sure that if I get a student in my lab, like, they’ll end up in a top tier institution. So you can come back, like, in the next year, and we can talk about you being my lab. Of course, I never came back, but now I think well, I’m at MIT, you know so.

But anyways, so, yes, I reached out to a bunch of professors and I didn’t get an opportunity, but I applied to an internship and I got the internship at Northeastern University. And that was definitely crucial because after that, when I came back to Puerto Rico, I started working in the lab of Dr. Martínez-Cruzado. And I was able to join the MARC program, which stands for Maximizing Access and Research Careers for minority students. And that’s basically an NIH-funded program that pays students to do research and to take specific advanced classes.

[“First Results” begins]

Gearin: As Yami’s portfolio of research experiences began to grow, the image of the scientists she grew up watching on her TV screen were replaced with new faces.

Acevedo-Sánchez: When I started doing summer internships, I saw that I was capable of getting into said programs and performing experiments. That helped me evolve my view. So I think that, yeah, definitely the summer internships and seeing the diversity in the interns definitely helped. I think that in a way helped me break that idea that only a specific group could be a scientist.

And that goes to a point that I always like to make, which is like the importance of having these programs, just allowing students to see that if they want to become a scientist, they can, and that it’s something that’s achievable by anyone. And it’s not something that is influenced solely by how you look or who you are.

[“First Results” fades out]

I will say, though, you know, some groups definitely have a harder time getting into science than others. And that is something that can’t be debated. So, in a way, who you are does influence, but it shouldn’t deter you from going into science, you know? I don’t know who said this to me, but that’s something I say to my friends: Don’t say no to yourself. Let others say no to you. You know, don’t limit yourself.

McElvery: One particularly formative experience was the Quantitative Methods Workshop, a week-long boot camp offered by the MIT Department of Biology.

Acevedo-Sánchez: This was my second time in Massachusetts, my first time in Cambridge. And it was a very intense week I remember.

[“Chafftop” begins]

McElvery: The following summer, Yami returned to Cambridge, Mass., this time for 8 weeks as part of MIT’s Summer Research Program in Biology, a.k.a. MSRP-Bio.

Gearin: She was placed in Alan Grossman’s lab, studying DNA replication and horizontal gene transfer in the bacterium Bacillus subtilis.

Acevedo-Sánchez: After MSRP, it was very clear that I was going to go to graduate school. And at the end of the day, it was just very logical to come to MIT. I already knew everyone and I knew the department and I knew the ins and outs. So MIT was my last interview and I knew. I knew. Like, I knew. As soon as I was here, I was like, if they take me, this is it. I’m not even going to think twice.

[“Chafftop” fades out]

Conor: When Yami arrived on campus in the Fall of 2018 as a grad student, she had a concrete plan and a specific list of labs she wanted to work in. But that changed when she started taking her required classes.

Acevedo-Sánchez: When I started graduate school, I thought I was interested in gene expression and gene regulation and all these types of genetic questions. And after taking some of the core courses, I realized I was more interested in biochemistry than in genetics. And that changed my plan entirely.

McElvery: By the time the annual faculty poster sessions rolled around in January, Yami was a free agent — prepared to hear what each faculty member had to say about their lab and their research.

Acevedo-Sánchez: And so the approach I took was just, OK, you’re going to listen to different talks and you’re going to see what sparks your interest. If someone starts talking and you come up with multiple questions, then you should talk to that person. And when Becky gave her talk, I remember that that happened.

Gearin: Assistant Professor Becky Lamason had recently opened her lab, aiming to explore how bacterial pathogens hijack molecular machinery in host cells to spread.

Acevedo-Sánchez: I wanted to be in a lab where, you know, everything that was discovered was game changing. And I think Becky’s lab definitely had that and has that still. And in addition to that, I really like the concept of, you know, we study host-pathogen interactions — and for that you really need to know microbiology, but also cell biology. And I like that I didn’t have to pick between either field. I could be in a lab that is constantly thinking about the bacteria, but also about the cell.

[“Crumbtown” begins]

We specifically study Listeria monocytogenes and Rickettsia parkeri. And I focus on Listeria monocytogenes, which is a human pathogen that causes listeriosis.

McElvery: The disease mostly affects immunocompromised individuals and newborns. Precisely how Listeria spreads from one host cell to another remains a mystery. But the Lamason lab suspects the process goes something like this:

Gearin: The pathogen enters the host cell and commandeers the host’s machinery to assemble a tail of proteins and rocket around, ramming into the cell membrane.

McElvery: That force creates a protrusion poking through to the membrane of the neighboring cell. Somehow, the cell engulfs the protrusion into a membrane-bound bubble encircling the pathogen.

Conor: Once it’s safely inside the new cell, Listeria escapes out of its bubble and the infectious cycle continues.

[“Crumbtown” fades out]

McElvery: As a postdoc at UC Berkeley, Becky conducted a type of genetic screen, known as an RNAi screen, that helped curate a list of potential proteins that could be involved in cell-to-cell spread.

Conor: On that list were two types of proteins —

Acevedo-Sánchez: Caveolins and PACSIN2 —

Conor: Which healthy cells use to transfer material into the cell through a process called endocytosis.

McElvery: This could signify that Listeria is co-opting the host endocytosis machinery to spur its own spread.

[“Lo Margin” begins]

Acevedo-Sánchez: We knew at the time that these proteins were positive regulators of spread. So, the bug needs these proteins to move from one cell to another. But we really didn’t know how — and at this point we don’t know how. I decided to pick that project because I wanted to figure out the molecular, mechanistic type of a process that was happening for this regulation to happen.

And we know that caveolins and PACSIN2 interact. And in their native environment, they form a membrane structure called the caveoli that’s important for tension buffering, and also for trafficking. So we know that they have some sort of involvement. But the types of questions I’m addressing right now are: Does Listeria need this interaction to happen for cell-to-cell spread to happen? And how exactly is it that these proteins are facilitating cell-to-cell spread in Listeria. But as of now, I’m just introducing a CRISPR system to the Lamason lab. Before that, all the work we had done was RNAi-based.

[“Lo Margin” fades out]

McElvery: Both RNAi and CRISPR-Cas9 are gene silencing tools. RNAi targets the mRNA to prevent protein expression, but CRISPR acts on the DNA to edit the sequence and permanently silence the gene’s expression.

Gearin: RNAi is also an older technique has more off-target effects than CRISPR. At the moment, Yami is working to make the cell lines she needs to create a CRISPR system to study the role caveolins and PACSIN2 play in Listeria’s spread.

Acevedo-Sánchez: Yeah, making the cell lines, validating them just to make sure that they’re behaving as the RNAi based work suggests that they should be behaving. And then just addressing some of the key questions I need to address to launch later pilot experiments. And so now it’s a lot of just building and cloning, making cell lines and cloning a bunch of mutants. So a lot of time in the tissue culture room for sure.

McElvery: But Yami also makes space in her schedule to share some of the lessons she has learned with others in the community.

Acevedo-Sánchez: I try and split my time between just like doing lab stuff and then like doing other things outside of lab. So I’ve tried to be involved in kind of, like, these diversity, outreach types of activities for the department.

Gearin: Her outreach activities include working with the MIT Biology and the Office of Graduate Education to recruit students; serving as a “BioPal” and mentor to younger Biograds; organizing events for the student-led Biology Diversity Community; and speaking to younger students back home.

[“Plain Grey” begins]

Acevedo-Sánchez: Every time I get a chance, I try to talk to students in Puerto Rico in high school about like science and just show my face and be like, you can be a scientist too. I always think about that and just how much I’ve learned in like five or four years, it just amazes me.

You’re not in graduate school because you know everything. If so, you wouldn’t be here. You’re here because you can learn and you showed that you can learn. And I think that over the years I’ve been able to see that, you know, and I think that’s true for everyone in graduate school and in life, like, if you don’t know something, you can learn it. Resources are definitely not evenly distributed. But if you look hard enough, I’m pretty sure you will look for the appropriate resources. And, you know, I’m here. Like, I’m definitely a resource that people can utilize.

To people that are in science, just keep in mind how important it is to reach out to these communities that don’t necessarily have these resources available. Because, you know, we don’t know if the next big discovery lies in the hands of someone who is in this neighborhood that does not have these resources available because of their upbringing.

[“Plain Grey” fades out]

Gearin: Well, that’s all for today. Next time, tune in to hear about a student who is bringing deep learning techniques to bear on the mysteries of microRNAs, which are short RNA sequences that are essential to regulating gene expression.

[“Something Elated” begins]

McElvery: Subscribe to the podcast on Soundcloud and iTunes or find us on our websites at MIT Biology and Whitehead Institute.

[“Something Elated” fades out]

Gearin: Thanks for listening.

[“Something Elated” fades out]

Produced by Raleigh McElvery and Conor Gearin.

Music for this episode came from the Free Music Archive and Blue Dot Sessions at www.sessions.blue. In order of appearance:

• “Something Elated” — Broke for Free
• “Two Pound” — Blue Dot Sessions
• “Louver” — Blue Dot Sessions
• “Friction Model” — Blue Dot Sessions
• “Mercurial Vision” — Blue Dot Sessions
• “First Results” — Blue Dot Sessions
• “Chafftop” — Blue Dot Sessions
• “Crumbtown” — Blue Dot Sessions
• “Lo Margin” — Blue Dot Sessions
• “Plain Grey” — Blue Dot Sessions