What are the molecular mechanisms that keep different animal species from hybridising? Krista Gert, a recent PhD graduate from the lab of Andrea Pauli (Andi) at the IMP, investigated this question in zebrafish and medaka. After fruitful doctoral studies, Krista is looking for postdoc opportunities in reproductive and developmental biology of understudied species.
When did you join the IMP?
I participated in the Vienna BioCenter Summer School in 2016 in Andi’s lab. At the time, I was doing my master’s at Linköping University in Sweden. I had already joined a summer school in the United States during my bachelor’s, and I was excited to try out another one as a master student. I enjoyed my time at the IMP so much that I ended up completing my master thesis and then taking up my doctoral studies here.
How would you describe your PhD?
The lab’s focus is on the molecular mechanisms of fertilisation and early development. My project was about the species specificity of fertilisation in fish, particularly the protein Bouncer, which acts as a gatekeeper that selectively allows sperm to get in contact with the egg membrane. I found that specific changes between the zebrafish and medaka Bouncer proteins prevent cross-fertilisation of these species, and that Bouncer may play a role in fish evolution.
By switching this protein between eggs of the two species, I made fertilisation work between species that are normally unable to hybridise. Using this hybrid system, I explored the molecular mechanisms of zygotic genome activation, and was exposed to other research areas through collaborative projects studying the inheritance of DNA methylation and piRNAs.
Any highlight of your learning experience?
When I started in the Pauli lab, medaka wasn’t used as a model system there, so I had to establish it from scratch myself. It was very challenging, but incredibly rewarding. I also developed the hybrid system between medaka and zebrafish, which involved designing and testing cross-species IVF protocols – a real challenge! - and many more things. When I have a scientific question to address, I learn what I have to learn to get to the answer. If I have to make something work to achieve my goals, I make it work. I think perseverance and creativity are crucial skills in research. I’ve also helped other researchers use this newly established hybrid system for their own research, and supervised students to reach their objectives. Collaboration has been a highlight in my PhD.
Can you tell us more about the future position you’d like?
I’m not afraid of establishing new model systems and it’s something I’d be excited to do again in the future. Many of the molecular tools we use were developed in traditional model systems, but there are many more organisms out there whose biology is unknown.
There are two areas that I want to dive into in my next position: the conservation of endangered species on the one hand, and evolution and development on the other. I’m an experimentalist and a molecular biologist, so I don’t see myself becoming an ecologist. Instead, I’d like to continue investigating the molecular basis of reproduction, but in endangered or understudied species.
Do you have any species in mind?
I’d love to work with mammals whose mode of reproduction differs from usual model species or those which remain poorly studied: whales, marsupials, and afrotherians – a group of mammals that exclusively live on the African continent – are prime examples. During my PhD, I became fascinated by the reproductive biology of tenrecs, a group of Madagascan mammals in which fertilisation potentially occurs in the ovary, which is very unusual. This made me realise how little we know about reproduction in non-model species.
My dream would be to work with cetaceans. I'd like to establish and use in vitro approaches to try to expand our knowledge of whale reproduction, and hope to contribute to their conservation. So far in molecular biology, whales have mostly been studied from the angles of longevity and cancer evasion, but I’d like to tackle reproduction.
Do you have an example topic you could address in whales?
I could imagine a lab that investigates ageing in oocytes, and how that differs between mammalian species. Humans and a few toothed whale species are some of the only mammals known to undergo menopause, while other long-lived whale species remain fertile for comparatively longer periods of time. If you could establish an in vitro ovarian model from these species, it could make an interesting cellular and molecular comparison to human and mice models and help us understand mechanisms of reproductive longevity. In the longer run, this could be relevant for biomedical research and conservation biology.
What kind of PI would you like to work with?
What really matters to me is that my PI trusts me to do the best I can and develop my own research ideas. Ideally, our expertise would be complementary, so we can learn something from each other. I’d also like to have a PI who has a solid appreciation for a healthy work-life balance.
Was there someone who influenced you into becoming a biologist?
I’d name two: the first one is Linda Vick, a professor at my undergraduate university who was a very inspiring lecturer. She taught courses in zoology and developmental biology and the way she conveyed the course material made everything interesting. She’s a very knowledgeable and talented storyteller – I admire that. The second one is Andi Pauli, my PhD supervisor. She taught me to pursue my ideas, even if they didn’t fit my original plans, or if they were risky. If I found a question fascinating and relevant, she would encourage me to go for it. I really appreciate her love of fundamental biology.
Interested in Krista’s profile? Email her at krista.briedis[at]imp.ac.at