I have had a lot of fun at this year’s Experimental Biology conference. I always enjoy attending the symposia to listen to current research news as well as interact with fellow comparative physiologists at all levels of training. Here are the highlights from the sessions on Tuesday and Wednesday:
J. Hicks, August Krogh Lecture: “Tales from the heart: A comparative and evolutionary perspective of the vertebrate circulatory system”
Dr. Hicks gave a wonderful talk on the evolution of the heart and the physiological purpose of shunting that occurs in the crocodilian heart, which is four-chambered but has 2 aortas with the left aorta receiving mixed blood (oxygenated and deoxygenated) from both ventricles (image below). In mammals and birds, the right ventricle is responsible for pumping blood to the lungs to pick up oxygen then the left ventricle pumps the oxygenated blood throughout the body. Dr. Hicks found that as the metabolic demand increases, the left to right shunting of oxygenated blood increases, which promotes increased oxygen saturation of arterial blood. In contrast, under low metabolic demands, right to left shunting is favored because the oxygen demand is lower.
“Hydrogen Sulfide: Ecology, Physiology, and Clinical Applications”
This was a really interesting session. It opened with a talk given by D. Julian on how hydrogen sulfide is essential for some organisms, which actually have sulfide oxidizing bodies that metabolize it. Some nematodes have also evolved a symbiotic relationship with bacteria that rely on hydrogen sulfide. In separate talks by H. Kimura, JS Bian, and PJ Kemp, I learned that mammalian cells can produce hydrogen sulfide, which has been shown in mammals to have anti-inflammatory, cardioprotective and neuroprotective effects in addition to functioning as an oxygen sensor.
“Gastrointestinal Physiology and the Microbiome”
This was an entire session on microbes in the gut:
H. Carey gave a really interesting talk on how the intestinal microbes vary in ground squirrels during and following hibernation. She found that the diversity of microbes were higher in the spring after the animals had a chance to begin eating and repopulate the flora. Conversely, the diversity was lowest during the winter when the animals were not eating or drinking.
T. Stevenson et al., took this research one step further and discussed work with an extreme hibernator, the arctic ground squirrel. This animal hibernates for an impressive 200-270 days during which the body temperature drops to ~ -3 degrees C and basal metabolic rate is less than 2% of a non-hibernating squirrel. Similar to Dr. Carey’s findings, Dr. Stevenson observed that the intestinal flora was at the highest level in the spring after the animals had a chance to eat.
MGD Bello et al., discovered that the pattern of migration of H. pylori, a human gut microbe, is similar to that of human migration. It was mentioned that this important microbe is disappearing in our society with young children having little traceable amounts in their gut whereas elderly individuals have high levels. It is not clear how this shift in microbial flora may impact health.
MD Dearing et al., discovered that gut microbes may help herbivores detoxify secondary compounds from plants.