Life Lines by Dr. Dolittle

Sponsored by the American Physiological Society

EB2022: Facing Oxygen Challenges

I learned a lot about how animals adapt to changing environmental oxygen levels in the Experimental Biology symposium on “Functional Integration across the Oxygen Cascade in the Face of Challenging Environments.” Here is what I learned…

Photo of an American bullfrog by Carl D. Howe via Wikimedia Commons

The first presenter, Dr. Lara do Amaral-Silva (postdoctoral fellow at the University of North Carolina at Greensboro working with Dr. Joseph (Joe) Santin), spoke about her research on adaptations in the bullfrog “super-brain” that allow these animals to avoid brain damage resulting from oxygen deprivation during overwintering when these animals are literally frozen. Her research may someday lead to clues that can help humans.  

Dr. Jay Storz (left) and postdoctoral fellow Dr. Anthony Signore (right), University of Nebraska – Lincoln; Photo by Craig Chandler / University Communication

The next speaker, Dr. Anthony Signore (postdoctoral researcher at the University of Nebraska – Lincoln working with Dr. Jay Storz – also pictured above), presented research exploring how variations in hemoglobin help penguins hold their breath while diving as they hunt for food. His team’s research was recently published in the Proceedings of the National Academy of Sciences. Hemoglobin is the molecule in red blood cells that is responsible for transporting oxygen from the lungs to tissues throughout the body where it can be used for metabolism. Considering penguins can hold their breath for >30 minutes during a dive, it is perhaps not surprising they have lots of hemoglobin. To find out how their hemoglobin may have evolved, Dr. Anthony Signore and Dr. Jay Storz compared hemoglobin from modern penguins to the common ancestor of penguins. As it turns out, hemoglobin from the common ancestor was very good at capturing most of the oxygen the animals inhaled. Although it can bind the oxygen tightly, more recent penguin ancestors developed hemoglobin that could also readily release the oxygen at tissues. In fact, Dr. Signore reported that modern animals had almost no measurable oxygen in the blood after returning to the surface after a dive.  

Photo by Tomás Castelazo via Wikimedia Commons

Postdoctoral researcher, Dr. Naim Bautista (University of Nebraska – Lincoln), spoke about his research on the unique attributes of crocodilian hemoglobin based on his recent publication in the Journal of Experimental Biology. Like penguins, crocodiles can hold their breath a loooooong time. In fact, they are known for being able to dive for more than 2 hours! Unlike other vertebrates, it seems that hemoglobin from crocodilians is regulated by bicarbonate that is created when CO2 is taken up by the red blood cells. In fact, crocodilian hemoglobin can bind both bicarbonate and CO2, which decreases its ability to bind oxygen thus helping improve oxygen delivery to tissues.  

Photo of an Andean leaf-eared mouse from iNaturalist

The symposium was wrapped up by Dr. Jay Storz, who spoke about his challenges and observations of Andean leaf-eared mice, which were only recently discovered living at altitudes greater than 22,000 feet (6739 meters) above sea level. At that elevation, these are the highest known dwelling mammal. Talk about extreme hypoxia tolerance…and a difficult mammal to study! His research aims to unravel how these animals thrive at such high elevations – information I am sure many mountain climbers would be interested in learning about.   

Other sources:

NM Bautista, H Malte, C Natarajan, T Wang, JF Storz, A Fago. New insights into the allosteric effects if CO2 and bicarbonate on crocodilian hemoglobin. Journal of Experimental Biology. 224(15): jeb242615, 2021.

AV Signore, MS Tift, FG Hoffman, TL Schmitt, H Moriyama, JF Storz. Evolved increases in hemoglobin-oxygen affinity and the Bohr effect coincided with the aquatic specialization of penguins. Proceedings of the National Academy of Sciences. 118(13): e2023936118, 2021.

Categories: Agriculture, Aquaculture, and Livestock, Climate Change, Environment, Exercise, Extreme Animals, Hibernation and Hypoxia, Intelligence and Neuroscience, Nature's Solutions, Ocean Life, Physiology on the Road

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