Nancy describes her research and what she discovered, and explains how she enjoyed being part of the DigiBrain project.
Can you describe your PhD project - what were you trying to discover and what were the overall aims of the project?
Over the last few years, there have been a lot of genes that were found to be associated with psychiatric disorders. However, many of the functions of these genes in such diseases are still not fully known. Whilst there have been efforts from different researchers around the world to understand these genetic functions better, we are still a long way from understanding the whole picture.
My project was part of a consortium called DigiBrain, which is part of Digital Life Norway. One of the DigiBrain project’s main goals is to connect specific gene variants to different brain functions and disorders. The consortium is very diverse, with clinicians, computational biologists, physicists, and biologists all working together. Different groups within the consortium also use different model systems, for example, some only work with rodents whereas our work from NCMM centred on the use of zebrafish models to help understand the effects of these genetic mutations on the brain.
Did you focus on a particular gene for your project?
The clinicians involved in the consortium helped to identify two particular genes of interest and that warranted further research. They had observed that some patients in their clinics who had mutations in the genes typically associated with calcium channel function tended to have more severe symptoms of certain psychiatric disorders. The existing literature on the topic also highlighted that these particular genes were thought to have an impact on the severity of some psychiatric diseases. All this then helped us to decide that we would focus our research on these genes.
How did you further investigate these genes?
We obtained zebrafish that were genetically engineered to carry mutations in these particular genes of interest. Using larvae bred from these mutant fish, we compared several characteristics using several different methods. This included behavioural experiments, such as testing social interactions of the fish. We also observed deficits in the fish’s prepulse inhibition – a type of startle response that humans also have. This meant measuring physiological changes in the brain and could be determined by tracking the fish’s behaviour when they were exposed to different stimuli. We also saw that the fish with the mutations demonstrated some social defects, such as staying away from one another. In terms of their locomotor activity (or movement) this was harder to determine. A few demonstrated hypo locomotor activity, so they would ‘freeze’ more and weren’t so active, but generally, the larvae behaved normally in this regard.
We also observed that some of the larvae showed forms of hyperlocomotor activity. In zebrafish, this can be associated with seizure-like events, psychosis-like events, or anxiety. However, we needed to be certain as to what was driving this hyperlocomotion. With seizures, we would expect to see a spike in brain activity. To measure this activity, we conducted the zebrafish equivalent of an EEG (electroencephalogram). We didn’t see any significant differences here though and, based on the fact that EEGs are usually the gold standard for determining brain activity, we were able to rule out that the hyperlocomotor activity we were seeing was not due to seizures.
As a next step, we decided to test two different drugs that were already used in the treatment of schizophrenia patients. Surprisingly, one of these drugs, an antipsychotic, reversed the hyperlocomotor activity. The other drug, valproic acid, which is usually used to treat epilepsy as well as other conditions like bipolar and schizophrenia, slightly reduced the hyperlocomotor activity but its effects were not quite as strong.
What do the findings from this project mean for the future?
Based on our findings from this mutant and the genes we examined, we concluded that the behaviours we were observing were likely caused by a “psychosis-like” state. We were then able to make the argument that this particular model could work well for use in future projects to further explore drug efficacy and safety, concerning drugs for psychiatric disorders.
We are hoping that, since prepulse inhibition is one of the hallmark deficits of psychiatric disorders, we can use some of these mutant fish as a model to perform a drug screen in order to identify compounds that can help treat psychiatric disorders in the future. Hopefully, this will mean trying completely new compounds or repurposing some existing compounds or FDA approved drugs that are not currently known to be effective with regard to psychiatric disorders.
What makes zebrafish so useful for research projects like yours?
Zebrafish are a very simple model to use, which makes them very useful for, among others, psychiatric disorders. As many as 70% of the genes that cause disease in humans can also be found in zebrafish. They’re also very easy to manipulate and engineer as their genome has been fully sequenced. Furthermore, they also respond well to many of the drugs used in humans, so zebrafish are perfect for things like toxicology screening and pharmacology. We use them at the larval stage, which is when they are optically transparent, making it easy to track them and see clearly what’s happening inside the body and the brain. There is much talk of reducing the use of animal models and, as we are using zebrafish larvae, these are less sentient than rodents or primates.
What have you most enjoyed about your project?
One thing I loved was working with multidisciplinary teams through DigiBrain. This setting gave me a lot of valuable feedback. It was also a useful learning curve; sometimes when I was presenting data or giving a talk, I had to factor in that I was talking to physicists, mathematicians, clinicians and many others who perhaps didn’t have full knowledge of the type of work I do. It was really valuable to learn how to talk to these people and explain my research in a way that they could understand. The variety of different expertise within the consortium was also very interesting; I learned from their different fields and their feedback was very useful. Some of the analyses we did, such as the electrophysiology to measure brain excitability, meant I could use the expertise of a physicist, for example.
How have you found being a PhD student in Norway?
I really liked the research schools that Norway offers. These are open to those working within similar domains. There is one for pharmacy students for example, where PhD students from the whole of Norway can come together. The school organises scientific and popular science events, so it’s great for meeting lots of people and building your network. The research schools also host courses, and you can suggest topics that might be useful. They also offer some funding for travel to help with attending conferences or training.
The Centre for Digital Life also had a research school that I was part of and they funded my internship during my PhD, so it was a wonderful resource.
What are your plans for the future?
I am very open-minded about what comes next! I love to teach, and in the past worked as a graduate teaching assistant so this could be something I pursue. I also like anything related to regulatory policy, such as the regulation of new technology, scientific regulatory policy, or supporting in these areas. I’m also interested in science communication and dissemination. I think the need for sharing reliable and accurate scientific information has become all the more apparent during the COVID-19 pandemic. There has been quite a lot of distrust towards scientists from different areas of the general population. I think good communication and transparency here can only help to overcome this problem.
Nancy completed her PhD in the group of Dr Camila Esguerra. Commenting on Nancy’s time in the group, Dr Esguerra adds:
Nancy has been a joy to work with and to mentor during the past four years. She has shown an incredibly positive attitude, cheerful disposition and team spirit, alongside hard work and perseverance throughout. For this, she must truly be commended. Her project was high risk with many unknowns when we started on the journey together to model schizophrenia in developing zebrafish, and we encountered a number of tough and unexpected challenges. Nancy tackled them very well, applying critical thinking and a strong work ethic to ensure quality, reproducibility and validity of her results. It has been a pleasure to witness Nancy develop and to mature as a researcher. I wish her much success in her next career stage!
Read more about Nancy’s research in a further interview with Titan.uio.no at:
Muterte akvariefisk kan gje svar om psykiske lidingar https://titan.uio.no/farmasi/2021/muterte-akvariefisk-og-psykiske-lidingar?utm_campaign=fai&utm_medium=akvariefisk&utm_source=ncmm (available in Norwegian only).