Cell Division's Missing Link: Dr. Masayuki Onishi

headshot of Dr. Masa Onishi, man with black hair

In this episode of BioGist, Tyler Edwards, a member of the class of 2022 majoring in Biology, interviews Dr. Masayuki Onishi, an Assistant Professor in the Biology department at Duke University.

Listen to hear Dr. Onishi describe how a drawstring-like structure used in the cell division process is a missing link in the tree of life.

To find out more about Dr. Onishi, visit his lab website at https://sites.duke.edu/onishilab/  and follow him on Twitter @onishilab

Listen here





Cell division, myosin,  structure, duke university, genes, Chlamydomonas reinhardtii, algae, flagella, biology


Tyler Edwards, Dr. Masayuki Onishi

Tyler Edwards  00:03

Hi there. I'm Tyler Edwards and welcome to BioGist where we bring you the gist of biology at Duke University. This time, I had the great opportunity to speak with Dr. Masayuki Ohnishi, and Assistant Professor here at Duke. Dr. Onishi, it's great to have you here. And my first question for you is: what do you study?

Dr. Masayuki Onishi  00:23

Yeah, thanks, Tyler for having me. Yeah, it's great to be here. And I like to introduce myself as a geneticist and biologist who's passionate about anything that involves cell shape, cell division and changes in those processes. So what do I study? So I study, the mechanism of cell division in eukaryotic organisms, so this is, you know, essential process to biology, and we are really passionate about understanding how this process works. And currently, we use this model [unclear] Chlamydomonas reinhardtii, which is one of the green algae and you can also find two flagella or cilia and Chlamydomonas use these flagella to swim around. If you put them under the microscope, you'll often find them moving about using these two cilia as if they are swimming by breaststroke. And it's not a big, you know, common system to study cell division. So I continue, you know, if you're interested why we decided to use this organism. Do you want to hear about it?

Tyler Edwards  01:31

Yeah, for sure. Yeah, I saw something about how C. reinhardtii is evolutionarily close to plants, but it divides like an animal. And I'd love to hear more about that.

Dr. Masayuki Onishi  01:43

Yeah, absolutely. That's exactly right. The problem is that the major mechanism that's believed to be essential for division in animals, is not conserved in this Chlamydomonas reinhardtii. And therefore, there is a huge question of how do they do that? Right. And this is a very simple question, but it has big deep implications behind it. And the reason why is that the set mechanism that's believed to be important for cell division in animals, is actually conserved only in a small range of eukaryotic organs, animals, fungi, and some other related species, these organisms have this structure called the actomyosin ring, as the name suggests, this actomyosin ring is made of genomic actin cytoskeleton, and the type two motor protein called myosin. So acto-myosin. And these two and some other proteins comes together to form a ring, and then there's the plasma membrane, when a cell divides into two, this ring shrinks in size in there, by putting a membrane from inside of the cell border. You can imagine a bag, there's a ring like structure under one part of the cell in that main structure shrinks its size, through the membrane, like the purse string. But as I said earlier, this system is conserved only in animals, fungi, amoeba, and some related species. What that means is that the common ancestor of these vast types of eukaryotes also divided like animals, but they didn't have the structure that's important for division.

Tyler Edwards  03:30

Gotcha. So it sounds like this is like a missing puzzle piece for the tree of life. That's so cool.

Dr. Masayuki Onishi  03:38

I actually call it a missing link.

Tyler Edwards  03:40

Absolutely. Absolutely. Yeah. So I've, you mentioned a couple of different methods. And I'm curious about a) which of those techniques do you feel are most important for your work, and b) if there's any of them that you really enjoy doing?

Dr. Masayuki Onishi  03:54

Yeah. So always have to do genetic screens to identify something new. This is the exploratory part of our results. So we are actually going out into unknown territory and try to find something new. That's the genetics part. And this is something that I truly enjoy now is probably just because you're finding something new is always exciting. One bonus to that is you find your own gene, through your own screen, you get to name that gene.

Tyler Edwards  04:23


Dr. Masayuki Onishi  04:24

Yeah [laughs].

Tyler Edwards  04:25

That is so cool. Have you named any genes?

Dr. Masayuki Onishi  04:28

It was always my dream, to name my gene. Since we moved to Chlamydomonas we've named a few genes. And yeah, and that was pretty exciting.

Tyler Edwards  04:37

My next question for you is so you and you've talked about this a little bit, but what what gets you excited about your research?

Dr. Masayuki Onishi  04:46

The reason why I feel passionate about doing research is deep sense of contribution to the society and that's through my research itself, and also through training that I provide to students and other trainees such as postdocs.

Tyler Edwards  05:03


Dr. Masayuki Onishi  05:04

And that part actually is connected to what gets me most excited and happy about doing research. And that's when someone I'm working with makes a new discovery. And they get excited about their discovery. Of course, you know, when I find that usually, I'm super happy, excited. But you can be sure that if someone you work with has the same experience, then the joy is outweighed by by 100 fold. You know, I've worked with three or four people so far, but I've already had that, that joy.

Tyler Edwards  05:37

That is so sweet! So I'm curious about what things you're passionate about outside of science.

Dr. Masayuki Onishi  05:43

I used to be an avid cyclist, and I used to bike least 100 miles every week and 200 on my long rides. So I think most of my best research ideas came up while I was biking.

Tyler Edwards  05:57

My next question is, what do you hope that people learn and know about your research?

Dr. Masayuki Onishi 06:03

Now, one of the things that I hope my research contributes to the Duke community is the sense that even though research in any field has been going on for many years, there's always something new, something important, and something exciting to start studying. It's about going outside of the beaten path, then I hope that our lab can set an example of doing that.

Tyler Edwards 06:32

Thanks for joining us for BioGist. Also, thank you to the Duke University biology department for supporting this podcast and Poddington Bear for the music. See you next time.