microRNAs & cycling hypoxia

Many fish species live in a state of constant, overlapping environmental fluxes including daily or hourly cycles in oxygen level. During these cycles, fish rapidly switch between periods of tolerance (hypoxia) and periods of performance (normoxia).

My postdoctoral work investigates how fish co-ordinate tolerance-performance shifts at the molecular level. I'm focusing on microRNAs, molecules that act as transcriptional or posttranslational regulators in many physiological processes. microRNAs turnover rapidly and can target specific organelles, and may play a key role in modulating the coping response to oxygen cycles.

(Publications coming soon!)

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Mechanisms of lampricide toxicity

Sea lamprey invaded the Great Lakes in the early 20th century, and continue to threaten populations of native fishes. Control of these parasitic invaders involves regular application of specialized pesticides - TFM and niclosamide - to nursery streams containing lamprey larvae. 

My postdoctoral work investigated how niclosamide and TFM-niclosamide mixes directly affect the mitochondria of sea lamprey to cause their toxic effects.

Key papers in this research area:

Niclosamide is a much more potent toxicant of mitochondrial respiration than TFM in the invasive sea lamprey (Petromyzon marinus)

Exploiting the physiology of lampreys to refine methods of control and conservation


Intermittent cycles of hypoxia

Periods of low oxygen are a fact of life for many fishes, and physiologists have a good understanding of how fish cope with stable, prolonged periods of low oxygen. However, we have much poorer understanding of how fish cope with repeated cycles between low and high oxygen, even though we know so called patterns of 'intermittent hypoxia' are very common in the wild. 


My PhD thesis investigated how killifish cope with low oxygen, and how these fish use different strategies to deal with daily cycles of hypoxia-reoxygenation compared to constant exposure to low oxygen conditions.

Key papers in this research area:

Distinct physiological strategies are used to cope with constant hypoxia and intermittent hypoxia in killifish (Fundulus heteroclitus)

Distinct metabolic adjustments arise from acclimation to constant hypoxia and intermittent hypoxia in estuarine killifish (Fundulus heteroclitus)

Interspecific variation in hypoxia tolerance and hypoxia acclimation responses in killifish from the family Fundulidae

Hypoxia acclimation alters reactive oxygen species homeostasis and oxidative status in estuarine killifish (Fundulus heteroclitus)

Rapid and reversible modulation of blood haemoglobin content during diel cycles of hypoxia in killifish (Fundulus heteroclitus)

Aside from killifish, I've also worked in this area in the context of intertidal plainfin midshipman fish from the west coast of North America, which endure long periods of emersion during low tide.

Key papers in this research area (in collaboration with the Balshine lab, McMaster University):

Parental males of the plainfin midshipman are physiologically resilient to the challenges of the intertidal zone

Nesting on high: reproductive and physiological consequences of living in the intertidal zone

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Other projects

I'm broadly interested in how animals, especially fish, cope with both natural and human-generated environmental challenges. Check out my Academic Publications to learn more about the cool side projects I've worked on!