Maddison Reed, a Hamilton native who fell in love with Ottawa during her undergraduate studies, has unlocked one of nature’s most critical survival mechanisms. Her groundbreaking research reveals the neurochemicals involved in how fish detect low oxygen levels and instantly alert their brains to take life-saving action. As a PhD student in the Department of Biology, Maddison became fascinated by a fundamental question: how do animals sense when oxygen levels drop dangerously low? It’s a matter of life and death for fish, especially as climate change warms our waters and drains the oxygen they need to survive.
“In zebrafish, there are special cells in the gills that can detect low oxygen levels,” Maddison explains. “Somehow, these cells send an urgent message to the brain, triggering immediate, life-saving changes throughout the entire animal.”
But how? “The first cell responsible for sensing low oxygen sends a signalling molecule to nearby neurons to activate a pathway that will transmit that signal out of the gills and to the brain,” Maddison says.
“Understanding how other vertebrate species detect and react to hypoxia may also inform how we treat human diseases associated with hypoxia.”
Maddison Reed
— PhD graduate, Department of Biology
While scientists had long suspected this happened, Maddison and her team cracked the code, identifying the specific cells and neurotransmitters involved in oxygen sensing among non-mammals. Using zebrafish as their model, the team described the precise signalling molecules generated within the gill that are responsible for relaying this critical survival message to the brain.
“This research provides crucial insights into how aquatic animals might adapt to our changing world,” Maddison says. “And understanding how other vertebrate species detect and react to hypoxia may also inform how we treat human diseases associated with hypoxia.”
The discovery was so significant that the Department of Biology nominated Maddison for the prestigious T.W.M. Cameron Outstanding PhD Thesis Award from the Canadian Society of Zoologists, an honour that still amazes her. “It’s still kind of hard to believe that I was nominated for that,” she says with characteristic humility.
But behind the science is a story of teamwork and resilience. “Experiments fail all the time,” Maddison laughs. “That’s something you don’t expect going in. You spend days, weeks even, and sometimes things don’t work. But there’s value in those failures. They’re how you learn.”
She credits the tight-knit Department of Biology for supporting her through those tough moments. Her supervisor, Professor Michael Jonz, provided his support and guidance from day one. Other professors like Jan Mennigen and Kathleen Gilmour also helped shape the project into the award-worthy thesis it became.
Beyond the lab, Maddison built a community of researchers and friends, hosted physiology seminars and mentored undergraduate students. “There’s such power in collaboration,” she says. “Science isn’t something you do alone. Everyone brings something unique.”
Today, Maddison is continuing her journey as a postdoctoral researcher at the University of Oxford, one of the world’s leading research institutions, under Nobel Prize winner Peter Ratcliffe. There, she’s working in a lab focused on cancer and oxygen sensitivity, helping to establish zebrafish as a model for studying these processes at the molecular level. “Mutations in the hypoxia-sensing pathway have been implicated in many different types of cancer,” she notes. “The more pieces of this pathway we understand, the more therapeutic targets we will have.”
When asked what advice she’d give to aspiring biologists, Maddison shares a refreshingly simple answer: “Follow what excites you. Let curiosity guide you, not just career plans.”
Her own journey proves the power of that approach. What began as curiosity about fish physiology has led to research that could impact both wildlife conservation and human medicine.
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