Episode 02: Kristina Micheva, PhD

The following interview was conducted in-class, during the Spring 2021 session of Hidden Figures: Brain Science through Diversity, taught by Dr. Adema Ribic at the University of Virginia. What follows is an edited transcript of the interview, transcribed by Misha Alam, Isabelle Sajonia, and Matthew Mehfoud, who also drafted Dr. Micheva’s biography. Editing (for brevity) was by Dr. Adema Ribic. The original recordings are available in Podcasts.

Dr. Kristina Micheva is a Senior Research Scientist at Stanford University. She completed her undergraduate studies at the University of Sofia, Bulgaria, and later moved to the University of Montreal, Canada to pursue her Ph.D. Dr. Micheva moved to Stanford for her postdoc and joined Dr. Stephen Smith’s lab, where she developed array tomography, a technique that enables high-resolution and high-throughput visualization of proteins in tissue sections using standard light microscopy. Dr. Micheva currently uses array tomography to study how different brain structures develop and change with experience. Dr. Micheva is a third-degree black belt in karate and teaches karate to children in her free time.

Dr. Micheva, can you tell us a little bit about your background-where do you come from?

I am from Sofia, Bulgaria. I was born there and I studied biology at the University of Sofia. I also earned my master’s degree in plant ecology as it was the only available research at the time. I was lucky to get a research position after that in a lab that used electron microscopy, which is where I learned that technique.

When did you move to the USA?

I went to Montreal in Quebec for my Ph.D. studies first. I worked with Dr. Clermont Beaulieu, and I was lucky that I was their first student. I also had to defend my thesis in French and that was exciting. After that, I did a postdoc at McGill with Dr. Peter McPherson, which is when I went to Marine Biological Laboratory (Woods Hole, MA) neurobiology course for two months. That was a really great opportunity and I actually returned later to teach in that course.  

What did you research during your Ph.D.?

That’s easy-I was plucking out rat whiskers! The idea was to study how sensory experience changes the development of the brain, specifically in the cortex. Rodents have this very cool organization where you can find the place for each whisker in their brain. That way, one can trim the whiskers or stimulate them with vibration and see what happens in the cortex. I would pull the three middle whiskers and leave the rest intact for my project. I’d let the rats grow up and then I’d look in their brain for changes in synaptic circuitry.

What methodology did you use at the time?

I used electron microscopy. I spent a bunch of years counting different synapses in the parts of the cortex that correspond to the whiskers that I pulled out versus other parts where the whiskers were intact. I also kept track of how many synapses were inhibitory how many were excitatory. I found a reduction in inhibitory synapses on spines after whisker trimming. Even more exciting, several years later, another group showed the complete opposite after whisker stimulation. One really cool thing that I enjoy a lot in science is how you do something and then somebody else takes it and goes further with it.

Did you move to Stanford as a postdoc?

Yes. I moved to Stanford, to work with Dr. Stephen Smith, which is where we developed array tomography. Initially, we had a really bad fluorescent microscope stuffed somewhere in the closet so I would go there and work and try to see if my staining worked. I did this staining for a dendritic marker, and went into a dark room and saw the bright lines going all in the same direction and I was so excited. I was telling everybody how it works and I was really excited for several weeks. But then I went back to my samples and realized that what I had initially seen was not the antibody signal-they were just folds in my section.

What drew you to Stanford for your postdoc and how do you think your department or maybe even the institution as a whole is doing and helping underrepresented groups overcome some common barriers for research?

I ended up at Stanford because of the neurobiology course I took at MBL-this is where I met Dr. Smith. What also helped was the fellowship I got from MRC which allowed me to go anywhere I wanted. My department is definitely doing a lot and trying to make sure that everybody feels included and

welcome.

When did you realize how important array tomography was?

When we figured out that you can combine it with electron microscopy to see both where different molecules are and the ultrastructure.  

What is the most challenging or difficult part of array tomography?

When you're trained in electron microscopy is, it's kind of an extension of what electron microscopy is. I usually tell people “oh it's easy, just follow the steps”. And then I realized how complicated that is and how many steps there are and how everything can go wrong.

Are you still studying synapses?

I started studying myelin, the insulating wrap of the neurons. With array tomography, we can visualize details not seen before with other types of microscopy.

What is the unique benefit of using array tomography?

I think one of the big benefits that I see is that it helps you localize a lot of different proteins in exactly the same structure. Usually, when you do immunofluorescence, you're limited to 3-4 proteins that you can see because most regular microscopes can visualize only that many colors. Array tomography has the ability to repeat the staining many, many times. At a time we're looking at three or four different probes, but you can do that 10 times with array tomography, so that gives you 40 different probes. The other huge advantage is that you can put it together with the ultrastructural studies.

How did you come up with the idea for a tomography?

That’s one of those lucky breaks. Around that time Winifred Denk started doing electron microscopy by cutting and imaging the surface of the tissue serially. That was a big advancement that we talked about in the lab and Stephen (Smith) said, “I wonder if we could do the same thing with staining: we can stain the surface, image, shave a section off of it and repeat”. We thought about it and I wanted to test it in order to prepare it for imaging. But that’s how that idea evolved.

You mentioned how antibodies involve a lot of trial and error. Is there anything that you did to narrow down the search and is there anything that you can do to predict which antibodies will work?

Most people start by trying to look at previous publications, what other people are using. A lot of times you can actually talk to the representative of the company and ask for small samples. There is an antibody company in UC Davis and we teamed up with them for antibody screening.

Can you tell us more about your research on myelin?

One unresolved question is the role of myelin in things other than speed (of action potentials). There is also traffic support of the axon or energy conservation, and I think those roles are very important, especially for fast-spiking neurons. I am also interested in what happens during the development.

What got you interested in the structure and kind of function of neuron circuits and how you narrowed down what part of the science you really wanted to research and partake in?

It's a combination of how things happen. My first job was sectioning and looking at brain structure so I think that's when I realized how beautiful it is, and how many things are unknown about it. In the type of research that I do, even when the experiment doesn't work, you still end up with beautiful images. That keeps you going because a lot of times the experiments don’t work. A lot of my research was by chance because you are researching one question and then you stumble into something else that's really interesting and you realize that nobody else knows anything about it, and that means you have to address it, so you jump on that one, and then something else appears. I have to admit it's not always some deep thought and hypothesis that motivated-it's just curiosity.

Can your research be extended into the neurodegenerative effects of COVID?

I hope eventually we'll be able to do that. I have a colleague that I hope will be able to provide me with some samples.

How do you stay motivated and patient despite obstacles in your research, especially when the outcome isn't as clear and whether you had any advice for how to stay patient through those tough times?

I wish somebody would give me that advice too! I am wired to find the positive things and focus on them and forget the negative, so that helps. Finding and enjoying whatever else is available and accessible right now helps a lot. I'm teaching karate to kids. I started doing more of that and doing zoom calls from my backyard, where I'm leading karate classes recently.

Do you think some of that positive attitude comes from growing up in Bulgaria?

Yes-there are setbacks here too, but also there are so many opportunities here that do keep you going and make you feel so grateful and optimistic.

What you are most looking forward to and is there any future research anything coming up that you're excited about?

I am currently both excited and not excited because I am in the middle of writing a grant application. That's one of the not-so-fun parts of being a scientist, writing grants and convincing people that what you want to do is really exciting. But, I am excited. One thing we want to add to the things that we're doing is to include the ability to learn more about the neurons by doing RNA sequencing from the interneurons. During electrophysiology experiments, we would take the nucleus out and find the genes expressed. I’d also like to work more with human samples.

What made you decide to stay versus going off the traditional tenure track route in the job market and having your own lab?

I decided to stay in the role of a research scientist because I really enjoyed working as a scientist. It also meant that I do not have to deal with administrative things.

Do you have a typical daily routine?

One advantage of being a scientist is that you can set up your own routine. A lot of the things that I do are on my own. From the time when my kids were young, I had to adapt my schedule a lot, and many times I wouldn't work during the day, but during the night.

You mentioned training karate-are you belted?

Yes, I'm a third-degree black belt-I just tested for the 4th degree.

This interview was conducted during the Spring Session of UVA’s Hidden Figures class in 2021. Class roster:

Addis, Lucas; Ahmed, Anushey; Akram, Amman; Alam, Maisha; Anderson, Sydney; Bhatia, Rhianna; Bonagiri, Paavan; Booth, Morgan; Clarke, Casey; Fisher, Grayson; Gandhi, Shreyal; Hossain, Mohammed; Rayan; Jensen, Kate; Kim, Michael; Lahham, Zina; Lea-Smith, Kori; Leffler, Schuyler; Leventhal, Emily; Mehfoud, Matthew; Morrisroe, Erin; Pham, Twindy; Sajonia, Isabelle; Sisk, Emma; Suram, Ananya; Wang, Jessica Beth; Webster, Tessa; Wilson, Gina. TA: McDonald, Amalia. Instructor: Ribic, Adema, PhD.