Wietske van der Ent: Zebrafish Is A Powerful Ally For Research And Medicine

The second guest of the podcast series was Wietske van der Ent, senior researcher in Camila Esguerra Group at Center for Molecular Medicine Norway (NCMM). Wietske provided a fascinating look into the realm of zebrafish research and its significance in studying neurodevelopmental disorders and cancer-related research. With a rich academic history from her PhD at Leiden University in Netherlands to her current role in Norway, Wietske shares her narrative of transition, highlighting the advantages and ethical considerations of using zebrafish as a model system in scientific studies.
We will explore the intricate process of handling those tiny organisms in a laboratory setting and touching upon the advancements in technology that aid in the precise execution of experiments. The practicality of zebrafish, coupled with their rapid development and transparent nature, allows researchers to observe physiological processes in real-time, making them a valuable tool in biomedical research. 

Kick back, relax, and let the waves of wisdom wash over you in this podcast episode – where learning meets laughter, and knowledge is served with a side of chill vibes.  

Wietske van der Ent (Linkedin): https://no.linkedin.com/in/wvanderent/en
Publication discussed in the episode: https://www.sciencedirect.com/science/article/pii/S0160412023005445?via%3Dihub
Camila Esguerra Group: https://www.med.uio.no/ncmm/english/about/organization/research-groups/esguerra-group/
For curious minds; https://projects.au.dk/nordic-embl-partnership/show-news/artikel/meet-camila-esguerra-converting-skeptics-to-believers-on-the-versatility-of-zebrafish-models

All music clips were used from the song "Jukka Tukka" after agreement with amazing band and friends 2+1 Jam band.
This podcast episode was created under the technical and official support of University of Oslo, Norway.

Transcript

Speaker 1 0:23

Welcome to our next episode of the podcast Inside Out, and today we have a very nice guest, witzke Hi Witzke. Hi so can you briefly introduce yourself, please?

Speaker 2 0:37

Yes, so I am Witzke van der Rente. I did my PhD in Leiden University and I'm currently a researcher at NCMM. I'm working with the group of Camilla Esguera and we're mostly interested in neurodevelopmental disorders and also the interplay between cancer and seizures.

Speaker 1 1:04

So you are doing the postdoc now at NCMM, or basically that period past now?

Speaker 2 1:10

I believe yes so I've been with NCMM for five years. So initially I was a postdoc and two years ago I transitioned to being a researcher in the group.

Speaker 1 1:22

So what was your motivation to move to Norway and maybe settle down in Oslo?

Speaker 2 1:29

Well, so I did my first postdoc in Paris in Institut Curie, where I was not working with ZebraFish, contrary to my PhD. And after this postdoc I realized that I would like to go back to this model system because it's really nice to work with. So I was looking for positions using ZebraFish models and, yeah, I saw a position posted by Camilla. So I decided, okay, let's interview for this, even though this was on neurodevelopmental disorders and my background is more on cancer research. But I thought, okay, let's try and let's see where it goes. And the interview was very nice and that's how I suddenly appeared in Norway. It wasn't really pre-planned, but I enjoyed a lot here.

Speaker 1 2:22

Have you visited Norway before you joined the lab, or was it your first?

Speaker 2 2:27

No, this was basically. The interview was online, and then the first moment I stepped foot in Norway was when I was moving there.

Speaker 1 2:35

Cool. So let me return a little bit to your PhD research. So you researched cancer and you researched Ewing's sarcoma. So this is like pediatric cancer.

Speaker 2 2:50

Yes, bone and soft tissue cancer.

Speaker 1 2:55

So what was so interesting for you to study this type of cancer, like for me, I know I was a little bit interested in the pediatric cancer myself during the study, so I'm wondering what was your motivation?

Speaker 2 3:09

Well, in the lab where I did my PhD initially I joined a research project that was setting up cancer models for any type of cancer. So this was during my master project and I was doing xenographs of different types. But then at some point we got into a collaboration with the University Hospital of Leiden and there they had the like the Dutch pathologist who got every case in the Netherlands of Ewing sarcoma passing his desk. So he was very knowledgeable about this and he was like interested in the fish model. So we decided to try it and this was one of the first cell lines that we tried. That was really aggressive, so initially I came out at it for more like, okay, this is working really nicely in this model. But yeah, then of course, being able to collaborate with this pathologist it's it was a really nice way to continue the project.

Speaker 1 4:09

So was it like a centralized care in at the research unit that specialized on the Ewing sarcoma, or was it like rather just like that they were focusing on the research of this topic?

Speaker 2 4:24

instead. So you mean like centralized care though. Yeah, yeah, so I think they got referred most of or all of the cases because he really specialized in this and then had the research group associated with this also, so they were doing a lot of research on, amongst other tumors, ewing sarcoma.

Speaker 1 4:48

Very good. How was it for you to work with zebrafish or, like you know, having it as as a aim for your PhD project, like you know, establishing the xenograft model for this type of disease? Did you enjoy it? Was it difficult and did you experience some you know drawbacks and moments of joy, maybe?

Speaker 2 5:14

So I like this model because it develops very rapidly. So within 24 hours you go from a single cell stage egg to something that almost resembles a complete fish and by three days, most of the major organ systems are already there. It also has a lot of transgenic lines that when you're looking at the fish using fluorescence microscopy, you can see the blood vessels growing to, for example, tumor cells, or you can see how the tumor cells interact with the immune system. So, as a student, since it was a very visual model, this was really exciting and very like beautiful in a way. So, yeah, this is one of the aspects that really drew me in at the time. And then, yeah, the more I worked with it, the nicer it was.

Speaker 2 6:13

Admittedly, though, after my PhD, there is always a downside to every model, right, and I think after my PhD, I wanted to work with some other models, like work maybe with just cell lines. So I switched away from the zebrafish for a while, but then, having this background, I always felt like, okay, but then how is it going to be in vivo? So I did, in the end, go back to it. But of course, working with animals, you have to be yeah, you have to really think about the experiments that you're doing and make sure that you're doing useful experiments and not wasting the animals, because, yeah, it is an ethical Balance. Let's say, like a case, the experiments that I'm doing, are they worth it? And, of course, in science is always needs to be the case. But, yeah, some people do perceive this as a downside.

Speaker 1 7:12

Yeah, definitely. I mean, I also work with mice, so I know the hustles of working with animals and how difficult it is. Actually was always curious with With these of these zebrafish model, you know, with the mice. They are quite tiny animals, but not that tiny as a rough ish right and if you want to do something, some experiments with them, or even like with the embryos, I would say it does a bra fish embryos? Yeah they are even Smaller.

Speaker 2 7:41

Yes.

Speaker 1 7:41

So how difficult is it to perform experiments with those? Do you use some robotics systems or something that can help you with that?

Speaker 2 7:49

Yeah, so working with zebrafish, you do have to be comfortable using a microscope, because normally the larvae you use them up to seven days post fertilization. This is very common. So then they're not much larger than four millimeters, so you can imagine that it's very tiny handleings that you're doing. And so, yeah, for example, when I'm in grafting cancer cells into these larvae, we use micromanipulators. So this is still its manual, but the needles that we use to inject cancer cells are Very carefully Moved, moved, but still this takes a lot of practice, especially if you want to go for four specific structures. So, for example, now I'm using brain cancer cells, so I want to implant this in the, in the brain area of the fish. It really takes a lot of practice to get these injections correct. And so there are now Companies and we are in collaboration with one of the companies who wants to develop an automated system for injecting cancer cells In order to not have this interperson variability when you're doing this research and I think that's it's quite important, because, yeah, it is.

Speaker 2 9:10

It is kind of an art and some people are better at injecting than others. I mean you have to have good stereo vision, you have to have the right amount of caffeine in the morning.

Speaker 1 9:21

Yeah, yeah, yeah, yeah yeah, there's.

Speaker 2 9:24

There's definitely Automation being developed for this.

Speaker 1 9:28

I think that would be very cool. I mean, I myself would be benefit some of the Automation for injection of mice because I mean it's not that probably that Difficult as to it with zebrafish, but it requires a lot of practice and also the mouse usually does not collaborate unless you Anesthesize.

Speaker 2 9:48

Yeah, yeah, and I imagine I mean I have never worked with mice, but there you're working, maybe more blind, I mean, you know this better. But for example, with the fish, because they're transparent, you do actually see where you're going with the needle. You know exactly where your needle tip is and if it's going in the hindbrain or if it's going in these veins, you can really control it nicely. So, yeah, as we, as you know, every model has their own peculiarity, that's true.

Speaker 1 10:17

What is the success rate actually for the injection into the brain? Let's say I'll see bra fish. I would say Currently.

Speaker 2 10:25

I'm on about 80% success, but the rates I do not dare to say. I think it's yeah. I mean normally when I'm injecting for two hours I would say I have about 150 Larvator work with the mouse, 150 Larvator work within the end that are properly injected in the correct sites and surviving After those injections.

Speaker 1 10:50

But yeah, that sounds very high to me. Success and the amount of animals. So now you're working with the zebrafish in epilepsy model and maybe also like in other contexts, of neurological diseases.

Speaker 2 11:08

Yes.

Speaker 1 11:09

So Was it a huge step forward, like for you, since, like you, used the cancer cell line and studied cancer in the context in zebrafish. How different was it working with the brain and neurological diseases like epilepsy? Is there any like, are there any challenges in this particular disease in zebrafish, etc.

Speaker 2 11:37

Yeah. So when I started in the Scare Group I came in pretty much blind. I mean, of course I've read up a bit, but this was not my field in the first instance. So, yeah, that was a bit of a yeah, a high steep learning curve. But in Camilla's group she values having people from different backgrounds, so we had some engineer, we had pharmacologist. Camilla herself is has a developmental biology background. So I think, yeah, there is the opportunity to learn from each other and so my colleagues really helped me a lot with getting acquainted with this model.

Speaker 2 12:22

And yeah, I mean, the first time I saw that you could actually implant an electrode in the fish brain at three days old, it was amazing to me. I did not, I did not expect that that was possible. But there you go. So it was yeah. And of course, yeah, I mean with any model, there's always some differences between the model system and the human system. So I'm not saying that zebrafish is the sale and all model, but I think it is a, as we talked about, like you can inject a lot of fish, you can use a lot of fish for your experiment, so it's quite a rapid model. So I think it's a good way to do some initial tests and develop your theories and then, once you have, for example, hit compounds that you want to use for a certain disease, or you have a certain theory, you can use different models also to validate this. Yeah, nice.

Speaker 1 13:20

Yeah, because I think it can be used for this high throughput discovery screenings, for example, since you don't need much of the space to house zebrafish.

Speaker 2 13:32

Yeah, correct, it's easy to keep a zebrafish larvae in 96 well plates and so considering that this is an actual organism and then you can just treat them with nanomolars of compounds. It's amazing. So you can screen a lot of larvae with minimal amount of drugs.

Speaker 1 13:55

I actually, when I learned about zebrafish at university or even during the animal course. I did here at the University of Oslo. There are so many tests, and behavioural tests as well. Do you have any favourite ones or do you use any of those on daily basis, when studying epilepsy, for example?

Speaker 2 14:16

Myself. I don't do a lot of behavioural tests anymore, but yeah, in the group we do, for example, locomotion tracking, because when the fish experiences a seizure it has this muscle contractions and this results in erratic swimming behaviour. But the one that I find always yeah, nice to see that this works is that larvae at such a young stage can experience anxiety and that it displays this sort of wall hugging behavior.

Speaker 2 14:51

It's called tic-mo-taxis and so when a fish is stressed out it tends to stay closer to a wall and just circle there, whilst if they are more relaxed I don't know if you can say that but less anxious, they are more exploratory and they go to the middle, for example in the six-wells plate.

Speaker 1 15:13

Interesting. Can you use it like? Can you use the prafish for studying? Like the anxiety in humans or like depression, for example? Would that be a useful model to use?

Speaker 2 15:27

Yes, you can at least look at, for example, drugs that have anxiolytic effects and look at that. So there are some models for that.

Speaker 1 15:47

So I will return a little bit more back again. So what is the research culture in the Netherlands versus, for example, France or maybe now in Norway? What do you like perceive it? How do you perceive it like personally, and if there's even like big differences or you know?

Speaker 2 16:11

I would say well, it's maybe a little bit difficult for me to compare research cultures from when I did a PhD and postdoc in France to here, because when I was doing my PhD I was in quite a large lab, so, and I was also I was a PhD student, so maybe at the time interested in different aspects of the organization than I am currently.

Speaker 2 16:36

I think that's a natural thing. But, for example, the difference between my PhD and the current group is that this group is a lot smaller. So here in Norway I have a lot more responsibilities and a lot more things that I'm working on. It's also natural, like progressing as more as you progress in your career and get more experience, it makes sense that you get more of the administration, responsibilities and all this type of thing. But in general and so in France, I was also in a large research group and there initially, when I got there, for me the system seemed quite different because they had much more permanent supporting staff. But it could also be that in this group I mean this was a group of quite well established Ewing's sarcoma researcher and so he had a lot of funds and so it was, I think, well, his lab was very established right, so he had a lot of supporting staff.

Speaker 2 17:41

So yeah, that's. It's very different types of labs that I was in. So yeah, you get different things.

Speaker 1 17:48

I think it's very nice to experience those differences because then you can realize like, okay, this was good here and this was maybe not that good or like would be done better when I look at it now from this different perspective. But I think it's very nice to explore and experience different research cultures. I actually wonder if you ever thought about leaving academia and exploring, you know, in the industry for example. I guess with your experience there must be quite a lot of industry targets for you.

Speaker 2 18:25

Yes, there would be. I mean, so far I've always been quite focused on academia. I enjoy the kind of creativity that it allows and that you have a little bit more flexibility to explore interesting side paths. But, for example, in the grants that I am currently on, we are collaborating with some small enterprises and so I see more how actually it is, how it works in companies that are working in the research field, because I've always been in academia.

Speaker 2 19:01

I've never done an internship in an enterprise, so this is really more my first experience. How does this look behind the scenes? Right, and yeah, it's also nice. I mean, it's a different way of working, but then it's also it seems that it's more like a culture of everybody together focusing on one goal, instead of, at least, what I've often experienced is that, okay, you have your project and you are responsible, perhaps in collaboration with students that pass through the labs, but usually it's you and your project. So, yeah, I think both have interesting aspects and I would like to stay in academia, but, as you know, it's also not for everybody an opportunity to stay.

Speaker 2 19:47

Because now, for example, I am already. I did my PhD in 2015,. So that's almost nine years well, less than nine years after I did my PhD in 2015. After, after defending and so funding opportunities, often for young researchers I'm already too old for that. So, yeah, then I would say that it crosses my mind more and more, the further I get in my academic career, to see, okay, maybe industry, but then in the end I'm really enjoying academic research. So if I can stay, I would love to yeah, that sounds good.

Speaker 1 20:22

Actually, have you ever wondered or talked about having your own group back in time, or even now still? Would that be something you would like to pursue?

Speaker 2 20:34

Yes, I would like to. I think I would enjoy it. There is, of course, becoming a group leader. You get more responsibilities on a certain side, so you're writing more grants here, doing more of the behind the scenes work and not being in the lab as much. I think I do enjoy being in the lab a lot, so I am enjoying the position that I currently have, but at the same time having your own group and sort of having your own like being the leader driver of the research and the responsible.

Speaker 2 21:18

it does appeal, of course, but it's not easy to. I mean, just wanting it is not enough. You do need to also have the perseverance and keep going and deal with setbacks of not getting grants and not getting things. So it takes a certain tenacity and we'll see.

Speaker 1 21:42

I got to hear myself also thinking about that future. So let's see.

Speaker 1 21:47

So I agree with all those things you mentioned. Actually, like you know, being in the academia there's like not necessarily like a must, but like you end up with supervising students. So personally I like that I supervise two students. I enjoy that. It's nice to see those young people growing and exploring their own way of science and how they think, how they think about stuff and how they improve over time. I think that's really nice to see. So how Is it for you Do you have experience with supervising, I guess, and how is your relationship to supervising in general?

Speaker 2 22:30

Yes, I've always really enjoyed it. So from when I was a PhD and we had, I think, 40% teaching responsibility, maybe that's a bit high. I don't recall it's been a long time since I did my PhD, but we had teaching responsibility and so mostly I felt that out by supervising students and, as you say, it's really nice to see yeah, introduce them to certain techniques, to models, and see how they respond and like, yeah, for example, you kind of re-experienced this first time that you are doing certain experiments.

Speaker 1 23:06

Yeah, definitely.

Speaker 2 23:07

Yeah, so I really liked that from since I was doing a PhD. So also here in Camilla's group I'm doing a lot of students supervision and I'm enjoying it a lot. It's just that I do see that the more responsibilities you get, the less time you have for them sometimes. And I feel that because of course I want to give the students the time they deserve and I do. But yeah, it's sometimes a little bit, you know, your day suddenly is gone and you still have so much to do.

Speaker 1 23:37

So yeah, yeah, I feel that the same. Yeah, yeah, I had some of those days myself. Yeah, exactly.

Speaker 2 23:45

Usually it's just some days and, yeah, normally it's very well manageable.

Speaker 1 23:51

Perfect. Okay, maybe I can ask a little bit about the negative aspects of academia for you, like if you ever experienced any negative part or negative sides doing research in academia or you know if there's anything that academia can change over time. It's not very flexible institution. Generally it takes some time to implement those new changes. So where do you see academia now and maybe where it should change in the future?

Speaker 2 24:29

Yeah, yeah, it's as you say, it's a difficult. Let's read that, let's see it is quite. Hmm, have to think a moment about this.

Speaker 1 24:50

Rigid no.

Speaker 2 24:52

Yeah, rigid is probably what I'm looking for. Yeah, yeah, it's. Academia is sometimes quite set in its ways. So, for example, you hear a lot of people saying that impact factor of journals should not matter this much and this is not a good metric for judging scientists, and I agree with that. But it's not looking like it's changing or going away Even though there maybe I'm in a bubble but that there's so many complaints about this, so it's difficult to judge this.

Speaker 2 25:33

And also academia, as we discussed, it's quite competitive because there's few positions and a lot of people. I mean, maybe the amount of people who start a PhD has increased a lot over time and the positions seem to have shrunk. I don't know how it is, but, for example, when I was leaving the university, I was already hearing complaints in the Netherlands that there's a lot of, a lot less funding for professors and that when professors had to retire, that they were not being replaced but their workload was being put on other people. So all the signs that I'm hearing, it's like it's so competitive and there's not a lot of support stuff. It would be nice if I could have a wish for academia.

Speaker 2 26:21

Yes, please, I would like that there is an extra layer between, maybe, the people running the head of the lab and postdocs, because postdocs are quite transient and also like, okay, you could say I'm a researcher but I'm also kind of, in a way, still transient. I don't have a permanent position in this lab, meaning that in many labs you just have a lot of turnover and there's just one or two people that stay in the same place, and so that sometimes feels like every time you kind of have to reinvent the wheel every few years, because then it's like oh yeah, how did these experiments go? Well, everybody who did them, are gone.

Speaker 2 27:11

So no, if I could have a wish, I would wish for a bit more permanent positions for supporting, like support for and the students and the head of the group, because they cannot do everything by themselves.

Speaker 1 27:24

That's a very true point I agree with that. So let's discuss a little bit your recent paper that was published in 2023. So in the Eora study there was like the link between one of those chemicals in a breast milk and the autism in newborns. Could you elaborate a little bit on that, Since I know that it costs a little bit more interest in Norway especially, and I found myself quite interesting.

Speaker 2 28:13

Yes, so this project was a collaboration with the Volker Health Institute, and so Norway is lucky in that they have a very nice mother-child cohort where they took breast milk samples and then followed up the children for many years, and so this has produced a lot of interesting results. And so what our collaborator was looking at is, like the occurrence of 27 known persistent pollutants in the environment, measured how much of these pollutants were present in breast milk and how this was correlated with autism in the children who, at the time of the study, were around 15 years old A bit more, a bit less and so they found this correlation between one of these chemicals beta HCH and autism. And in this collaboration we looked at what this compound was doing on a developing organism. So we exposed the zebrafish to it from a very early stage, only three, four hours after fertilization, and then see how it affected their brain development, and so we did see that it affected the dopaminergic population of neurons. It affected the behavior cell division. It had many aspects that it was affecting.

Speaker 1 29:41

I see. So it's not very good news, I guess, but since this beta HCH compound is forbidden to use nowadays, as it was forbidden from like by 2008, in Norway at least, and in Europe since, I think, 2008,.

Speaker 2 30:06

and in. Norway already in 1992, so yeah, more than 30 years ago.

Speaker 1 30:14

So we discussed this topic a little bit in advance. So you mentioned that it is stored in fatty fish quite heavily. So how is it? Is it healthy to eat those fatty fish, especially living in Norway, because it's a big part of the local cuisine?

Speaker 2 30:36

Well, I don't think Norway has a unique thing in here. No, it's. I mean it is fatty fish is known to be a bio accumulator, right? So the compound is a byproduct of pesticides and it's still used in some places as anti-laus, a compound against lice. So it is still being released in the environment and so it gets released in the water and then bio accumulates via plankton small fish and ends up in these fatty fish. So, yeah, it is present in this fish. I mean, this is as I said, the study was done in by measuring the amount of chemicals in the breast milk of mothers in the early 2000s, even though this compound had been banned for quite some time already.

Speaker 2 31:28

still they were being exposed to these compounds. So it's shocking like how, how long, even though we stopped doing something, this effect still continue on. So, yeah, it's something to be aware of, but it's certainly not the only thing. But yeah, personally, I still do eat fish. So there goes the show.

Speaker 1 31:51

Okay, don't don't spread the panic yet, but was there any correlation between the concentration found in breast milk of this compound versus the autism spectra?

Speaker 2 32:06

Yeah, so they did look at the different, like quartiles with higher concentrations or lower concentrations. That's how they divided the data. And yes, you do see, if you have a higher accumulation of this compound, there's a higher risk of autism developing.

Speaker 1 32:26

So yeah, I'm actually wondering since, like, how do you study the autism symptoms, let's say in zebrafish? Do you use some general markers or do you use some specialized essays to see the effect of those compounds on the zebrafish brain?

Speaker 2 32:49

So in the model that we are, in the paper that we published, we looked at the social behavior of the larvae at this point. I mean, this is certainly not the only aspect of autism, or even always the aspect, but this is one thing that we looked at and we did see that beta HCH did decrease the social tendencies of these larvae at early stages and then also we saw that it induced like an overproliferation of cells in the optic tectum and this is also seen in individuals with autism that they sometimes have like a thickening of the cortex because of overproliferation of the cells. So yeah, I see.

Speaker 1 33:34

Have you considered or is there any follow up on this, like you know, trying to find the treatment or something that could counterattack these symptoms by exposing this beta HCH Cj molecule, in zebrafish at least?

Speaker 2 33:58

Well, not from our group. Currently my projects have sort of gone a different way. But we did see that if we added precursor to dopamine, l-dopa, that this could counteract some of the effects. But of course we are working with very early stage larvae. To actually apply this in humans is maybe it's quite tricky, right, and yeah, well, yeah.

Speaker 1 34:32

I see. I mean I found it very nicely done the study and I learned a lot out of that. So I enjoyed it reading and nice to hear a little bit more from one of the first order of the study. So I would like to ask you actually about your advice, since you are a very experienced researcher and, of course, you was also a student back in the old days.

Speaker 1 35:07

So, I would like to ask you would you recommend to students like either now that are in the university or maybe considering study biology or medicine, that they might find interest in science in general? What would you suggest to them to help to decide if they would like to do the science or not, or if they would like to study those topics, for example?

Successful PhD Pursuit Through Prior Experience

Speaker 2 35:37

Well, I think I would advise them to try to get experience in different labs. Before picking your topic, I went this is against what I did, but it's always don't do as I do do as I say Now but I would advise them to try to get experience in different groups, like different methods, different diseases, different approaches, because there are so many interesting things to do and it's always difficult to make a choice. But when you start your PhD, it is an intense process, as you know Definitely. So you definitely have to enjoy it.

Speaker 2 36:24

So try to get as much experience beforehand and see, ok, where do you feel the most happy, and go for that.

Speaker 1 36:33

Yeah, thank you very much, witzke. It was nice to have you as a guest. Thank you, and have a nice day you too.