The Respiration Group.
This group is interested in animal respiration in the widest sense. How animals obtain oxygen and deliver it to their mitochondria, how mitochondria produce energy and are distributed in different tissues, how animals use the energy produced, and how they eliminate gaseous wastes (carbon dioxide and ammonia). These processes are explored at many different levels, whether the gas exchange and metabolism of whole animals, or gene expression in response to tissue oxygen supply. We are particularly interested in how these processes contribute to environmental adaptation, including to human influences such as climate change.
The photo shows a tropical fish, the jeju (Hoplerythrinus unitaeniatus) coming up to the surface to gulp air, which it stores in a modified swimbladder to extract the oxygen. The red trace shows its heart beat during this process, as an electrocardiogram. The heart slows before the breath and speeds up afterwards. All air-breathing fish show this variation in heart rate but no-one knows why.
The link below links to a film showing a giant mudskipper (Periopthalmodon schlosseri), a tropical amphibious fish which obtains oxygen by holding air in its gill pouches. The sequence shows it exhaling stale air, then filling up with fresh. In between, it ventilates water through the gill pouches three times, presumably to excrete carbon dioxide and ammonia. This bizarre gas-exchange strategy is associated with a life on tidal mudflats, where the fish defend deep burrows.
Please click here to download and watch the video
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David McKenzie works for the CNRS in France, in the Institut des Sciences de l’Evolution de Montpellier (www.isem.cnrs.fr), where he studies the respiratory and cardiovascular physiology of fish, both basic mechanisms and their applications in ecophysiology, ecotoxicology and aquaculture.
