Student Guest Posts: Profile of Dr. Brian Dixon

Tuesday, May 5, 2015

As part of the communication component in Dr. Swanson's Advanced Aquatic Ecology Course (Biol 606), graduate students from the Department interviewed several faculty members (students choice!) about their research interests and careers. Our second guest post is by Ashley Stasko (PhD candidate) and Rachel De Jong (MSc student) - both from the Swanson Lab.


Dr. Brian Dixon

Meet Waterloo’s Resident Fish Doctor – Dr. Brian Dixon

He has travelled to more than 48 countries. He speaks four languages. He owns a lot of hats, and every one of them has a story.

Meet Dr. Brian Dixon, the Canada Research Chair in Fish and Environmental Immunology. Dr. Dixon has been a faculty member in the Biology Department at the University of Waterloo for 15 years. His research is centred around understanding the immune systems of fish, which he’ll happily tell you is slippery business!

Which came first for Dr. Dixon - a love of fish or a love of immunology? Well, not quite either. Let’s rewind a few (undisclosed) years to when Dr. Dixon was a budding scientist. He always had a keen interest in animal biology, but during his undergraduate honours project at Wilfred Laurier University he found himself working on epigenetics in flax plants. When he began his MSc at the University of Guelph, he moved away from studying plants to studying vertebrates, but his interest in molecular biology stuck with him. His MSc research investigated cell cycle regulation using mouse cell lines.

After his MSc, he claims that the most important determinant of his future – serendipity - took over. He was unsure if he wanted to begin a PhD, but he was certain that he was looking for new experiences and wanted to look beyond those available in Ontario. A few applications later, he found himself working at a molecular laboratory in Halifax where he was introduced to molecular immunology, a subject he soon fell in love with. He loved it so much, in fact, that after a year of working in the lab he agreed to stay and work longer hours for less pay. In other words, he began his PhD.

As a PhD student, Dr. Dixon worked to improve the understanding of immune responses to cod worm, a parasite that had been harming the cod industry. Cod with heavy loads of this parasite were unable to be sold for human consumption; cod worm was thus a substantial economic threat. Cod worm requires seals as a host for part of its life cycle. Parasite eggs are released through seal feces, which then cycle through a number of invertebrate hosts before infecting cod. The research group that Dr. Dixon was working with targeted seals, trying to find a way to elicit an immune response that would reduce the number of parasite eggs released into the environment. The group made substantial progress, and by the time Dr. Dixon completed his PhD, cod worm was no longer an economic issue. Of course, that was because a moratorium on cod fishing closed the fishery, but the technology had been developed nonetheless and would have worked! The technology has since been applied to population control of both seals and deer, where a triggered immune response causes antibody expression on egg cells, which then are unable to implant in the womb.

After a few international post-doctoral positions, Dr. Dixon decided that fish immunology was where his greatest interests lay (not to mention, he thought it was a strategic choice considering how few fish immunologists existed in Canada). He was hired as a faculty member at the University of Windsor, and started his fish immunology research program. After two years, and with a little prodding from his wife, he decided to dust off his CV and look for a job in a more exciting city - and that’s how he came to be at the University of Waterloo.

Since beginning a research career at the University of Waterloo, Dr. Dixon has had the opportunity to work on many interesting projects that have introduced him to a wide variety of fishes, diseases, people, and countries. He has had students examine detailed protein-protein interactions in the fish immune system, the development of disease-resistant families of fish for aquaculture, and molecular markers in wild fish populations.

One of the most common research applications in the Dixon lab is improvement of fish health in aquaculture settings. Although the Dixon lab does not develop vaccines directly, research results do contribute to disease control by shedding light on the fish immune system. For instance, the lab is currently working toward a better understanding of the immunological processes involved in temperature-dependent diseases. Fish immune systems often shut down at temperatures near the lower end of their tolerance range. As a result, many cold-water specific diseases have evolved, and in a country like Canada this can have very expensive implications for sea-cage aquaculture.

Vaccines are one method for disease control in aquaculture. However, Dr. Dixon explains that vaccines often do not work well in fish because their immune systems respond differently than those of terrestrial vertebrates (for which most of the vaccine research to date has been conducted). Thus, another component of his research program involves aspects of population biology and genetics that help aquaculture facilities develop breeding stocks with higher natural disease resistance. He is currently involved in two such projects– one involving the largest Atlantic Salmon producer in the world -  based in Chile - and one involving an organic Chinook Salmon farm in British Columbia.

Dr. Dixon is also hoping to advance the field of fish immunology by developing research tools that will be available to other labs. In order to study the function of cytokine (signalling) proteins in fish immune responses, cytokine-specific antibodies are needed. However, antibodies for fish cytokines are not commercially available for research. Dr. Dixon is working with Cedarlane laboratories to develop and market these antibodies so they will become available to fish immunologists worldwide.

Dr. Dixon’s lab has many exciting projects currently underway. You can read more about his research here:

Dr. Brian Dixon

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