ECR Spotlight is a series of interviews with early-career authors from a selection of papers published in Journal of Experimental Biology and aims to promote not only the diversity of early-career researchers (ECRs) working in experimental biology during our centenary year, but also the huge variety of animals and physiological systems that are essential for the ‘comparative’ approach. Michael Lim is an author on ‘ Intergenerational plasticity to cycling high temperature and hypoxia affects offspring stress responsiveness and tolerance in zebrafish’, published in JEB. Michael conducted the research described in this article while a PhD candidate in Dr Nicholas J. Bernier's lab at the University of Guelph, Canada, investigating the impacts of anthropogenic activities on animals, and how research can improve our ability to understand and mitigate the effects.

Michael Lim

Describe your scientific journey and your current research focus

I started in research as an undergraduate student in Dr Chris Wood's lab at McMaster University. Under the mentorship of then PhD Candidate Alex Zimmer, I studied the effects of waterborne copper exposure, such as from mining effluent, on ammonia transport in rainbow trout. After catching the research bug, I continued studying anthropogenic impacts for my MSc in Dr Joanna Wilson's lab at McMaster University. I was part of a team of researching the potential impacts of effluent from thermal power plants on lake whitefish and round whitefish. Recently, I completed my PhD in Dr Nicholas Bernier's lab at the University of Guelph, where I studied the transfer of climate change-linked stress across generations in zebrafish. I currently work as a Policy Analyst at the Public Health Agency of Canada.

How would you explain the main finding of your paper to a member of the public?

When it comes to being stressed, recent research suggests that it may not only affect you, but could also affect later generations, including your children and grandchildren. This is not necessarily bad, as sharing information about stressful conditions with your offspring could help prepare them to handle similar stressors. However, it was not clear how this information was shared. My recent study on zebrafish has shown that when parents are exposed to climate change stressors – such as high temperature and low oxygen levels – they increase and decrease different levels of compounds associated with stress and cellular damage. Strikingly, these changes to the compound levels were associated with producing offspring that were more stress-tolerant than offspring from unstressed parents!

What are the potential implications of this finding for your field of research, and is there anything that you learned during this study that you wish you had known sooner?

For my field, my research helps shed light on potential mechanisms that may be at least responsible for the trans-generational effects seen in other studies that used environmental stressor exposures. Notably, my work provides a spotlight on the potential role of heat shock proteins, which have been gaining more focus in multi-generational studies because of their linkage with epigenetic modifications. In terms of anything I wish I knew earlier, considering the incremental, step-wise nature of research and understanding, I would have been happy even knowing just one aspect of my end results ahead of time (to help reach that next incremental research step sooner!).

Which part of this research project was the most rewarding/challenging?

Although perhaps more closely linked with establishing the design in an earlier study, the more challenging part of my work was designing the setup for mixed, cycling stressors. Understandably, most studies use single, static stressors and observe the resulting impacts of that exposure. However, nature is rarely so straightforward. To serve as a step towards more ecologically relevant exposures, I used multiple stressors (elevated temperature and hypoxia) which changed throughout time at rates that were similarly reported in the zebrafish's natural habitat (shallow waters in India). It was incredibly rewarding to see significant effects on my treatments that used this approach, and I'm looking forward to how future studies help move the needle closer to environmental relevance.

Recently fertilized zebrafish embryos under the microscope.

Recently fertilized zebrafish embryos under the microscope.

Why did you choose JEB to publish your paper?

JEB is a fantastic source of excellent studies in the field of comparative physiology, with several relevant studies to my work previously published with them. I wanted to be able to help add to that large body of work, and hopefully help push forward a future researcher's understanding.

Are there any important historical papers from your field that have been published in JEB?

I'm not sure if it would necessarily classify as ‘historical’, but my research questions were certainly influenced by work that came before me in JEB, including Ho and Burggren's 2012 paper ‘Parental hypoxic exposure confers offspring hypoxia resistance in zebrafish (Danio rerio)’ (doi:10.1242/jeb.074781). This paper demonstrated the potential for zebrafish to confer trans-generational stress resistance, and the importance of longer exposures. Also, Lockwood et al. (2017) ‘Maternal loading of a small heat shock protein increases embryo thermal tolerance in Drosophila melanogaster’ (doi:10.1242/jeb.164848) highlighted the potential role for heat shock proteins in conferring trans-generational stress resistance.

If you had unlimited funding, what question in your research field would you most like to address?

I would love to tease apart the relationship between the increased heat shock proteins and decreased cortisol transfer in my study and the resulting effects on offspring stress tolerance. There are many potential aspects that could have been changed, such as altered production, breakdown and excretion of these compounds, and it is unclear if my observed effects would be long lasting. For example, would increased heat tolerance be maintained until later in life? What about multiple generations?

What changes do you think could improve the lives of early-career researchers, and what would make you want to continue in a research career?

To be honest, more funding and financial support. It is an incredibly competitive field, with little funding to go around for all the talented individuals with fantastic research questions. There should also be more support for obtaining null results. ECRs have to walk a tightrope of taking on enough risk for their research to be novel and eye-catching for institutions to want to keep them, while at the same time consistently reporting large, significant results in order to publish. This has given rise to a culture where researchers may feel pressured to fudge results or only complete research they are certain will have significant effect, even if it is not relevant to their research question.

Michael Lim's contact details: Public Health Agency of Canada, Ottawa, ON, Canada, K1A 0K9.


M. Y.-T.
N. J.
Intergenerational plasticity to cycling high temperature and hypoxia affects offspring stress responsiveness and tolerance in zebrafish
J. Exp. Biol.