Tuesday: Grand Challenges in Physiology

Image from the American Physiological Society's website.  http://www.the-aps.org/mm/Conferences/APS-Conferences/2014-Conferences/Comparative Image from the American Physiological Society's website.

Tuesday was no less exciting than Monday!

Here are some highlights:

I thoroughly enjoyed a session called "Overcoming a Major Physiological Barrier: Adaptation from Saline to Freshwater Habitats" which highlighted the need for several species to shift how they regulate ion balance when they migrate between fresh water (ion absorption from the water) and salt water (ion secretion to the water).

Clements K, Bojarski L, Johnson K, McMillan S, White L, Angert E (Univ Auckland; Auckland Univ of Tech; and Cornell Univ). Presented research on gut microbes and how they are important to the host because they can convert dietary sugars to fatty acids in addition to providing amino acids to some species of animals. For marine herbivorous fish, gut microbes were found to produce significant quantities of amino acids to the fish tissues.

Vatner D, Yan L, and Vatner S (Rutgers Univ) showed some really interesting data for hibernating woodchucks (aka: marmots). They discovered that during hibernation marmots are protected from damage caused by heart attacks. During a heart attack, the lack of blood flow and oxygen delivery (ischemia) causes the heart tissue to become damaged. The marmots develop increased concentrations of an endogenous vasodilatory enzyme called endothelial nitric oxide synthase which helps to promote vasodilation (i.e. opening of the blood vessels) to maintain normal blood flow...much like how nitroglycerin works in humans to cause vasodilation thereby preventing a heart attack.

Sirsat SG, Sirsat T, Pineda M, Dzialowski EM (Univ North Texas) presented data showing that thyroid hormone is important in the development of endothermy (metabolic regulation of body temperature) in Red-winged blackbirds.

Buckley B, Sleadd I (Portland State Univ) showed that exposure of cells from cold-adapted antarctic fish to even small increases in temperatures of only 2degC causes cell death (apoptosis). This is not good news for these fish when considering climate changes predictions.

Wolf B, McKechnie A, Gerson A, Whitfield M, Smit B, Smith E, Talbot W, O'Neill J and McWhorter T (Univ New Mexico; Univ Pretoria; Nelson Mandela Metropolitan Univ; Univ Adelaid) presented data regarding the effects of climate change on bird species. Various species of birds were exposed to temperatures ranging from 30-64degC. Pigeons, doves, nightjars, and nighthawks were found to tolerate very high temperatures up to 60degC. In contrast, several species of passerine birds could only tolerate temperatures up to 50degC. The main difference is that species who can tolerate higher temperatures used mainly evaporative water loss (ex: from the skin or gular apparati) to lower their temperatures as opposed to panting. These findings explain why passerine birds tend to succumb to large heat waves in desert localities. Also not a good news for passerines given the predicted increase in heat waves.

Morash A, Ashmore T, West J, Griffin J, Montgomery H, Murray A (Univ Tasmania; Univ Cambridge; Univ Coll London) discovered that ketone bodies, produced when skeletal muscle is broken down during chronic exposure to low oxygen (i.e. hypoxia), can be used by the heart for energy in rats. They predict that ketone bodies may also help to protect the heart tissue from damage during hypoxic exposure. I wonder if the human heart can also rely on ketones for energy during a low carbohydrate diet when ketone production is increased...


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