Life Lines by Dr. Dolittle

Sponsored by the American Physiological Society

Diet and Exercise

Experimental Biology – Day 2

Yesterday was a great day for comparative physiology! Highlights from the seminars on comparative physiology: Melissa Reiterer, graduate student from Florida Atlantic University, presented her research on how freshwater turtles (Trachemys scripta) survive for long periods of time without oxygen and do not develop oxidative stress after oxygen is restored. The turtles are able to do this by creating their own antioxidants as well as eliminating oxidative stress. In contrast, mammals including humans, develop […]

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Obese rhesus monkeys develop diabetes too

A new study published in American Journal of Physiology – Endocrinology and Metabolism shows that rhesus monkeys (Macaca mulatta) who spontaneously develop obesity with aging are prone to insulin resistance and diabetes, similar to humans. The major goal of insulin is to lower blood sugar after eating a meal. In line with this goal, muscles respond to insulin by taking up large amounts of the sugar. Similarly, insulin blocks the breakdown of glucose […]

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What do frogs and humans have in common?

Leptin is a hormone that signals the brain to suppress appetite in humans. While researchers at the University of Michigan described a similar appetite regulating role for leptin in South African clawed frogs (Xenopus), they also discovered that leptin signals limb development in tadpoles. They suspect that this happens once there are sufficient energy stores to begin the process of metamorphosis. Shalitin and Kiess (2017) also described a role for leptin in skeletal development of children and researchers implicate leptin in […]

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Growing meaty fish

Similar to humans, muscle growth in fish is increased with exercise. Unlike humans, however, teleost fish are able to continue growing in length as well as weight throughout their lives. This type of meat, I mean muscle, growth happens in two ways: 1) muscle cells get bigger and 2) new muscle cells form. Researchers at the University of Barcelona in Spain wanted to know what effect moderate sustained swimming would have on the muscles of young […]

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The ultimate desalination plant: the eel esophagus

I love fish. The diversity of these aquatic creatures is so vast, I find them fascinating. Take the eel for example: In a study published this month in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, researchers wanted to link information they learned from sequencing the RNA of eels with understanding how the animals adapt to saline environments. During acclimation to saltwater, fish have no choice but […]

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The cause of stomach rumbling

The stomach and small intestine of many species moves rhythmically during fasting, something called the rhythmic ‘migrating motor complex’, or MMC. The MMC has 3 phases: no contraction, intermittent small contractions followed by regular large contractions. These contractions are thought to help clean the GI tract by moving along debris and bacteria as well as preparing our guts for the next meal. They are also the cause of ‘stomach rumbles’ when we are hungry. If […]

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Why orcas go through menopause

Orcas are one of only three species of mammals that go through menopause, including humans of course. A new study published in Current Biology may have discovered why this happens in killer whales. Examination of 43 years worth of data collected by the Center for Whale Research and Fisheries and Oceans Canada, revealed a remarkable finding about the costs of reproduction in orcas. Older mothers tend to spend more time taking care […]

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The obese marathon mouse

As the name implies, Dummerstorf marathon mice are bred to run. If allowed to be sedentary, these animals can build up quite a bit of fat within their peripheral tissues even if they do not overeat. If given an exercise wheel, however, they burn fat very quickly. In a new study published in the Journal of Comparative Physiology – B, researchers discovered that the livers of these mice have an increased ability to not only […]

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Will Santa have to find replacements for his reindeer?

New research presented at the British Ecological Society, Liverpool shows that reindeer are shrinking. These findings come from a survey conducted between 1994-2010 in Svalbard, a Norwegian island, which found the animals have lost about 12% of their body mass over this timeframe. The research team thinks the shrinking reindeer phenomenon might be caused by global warming as females have increased access to grasslands and give birth to more calves annually than in […]

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