Life Lines by Dr. Dolittle

Sponsored by the American Physiological Society

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Domestic zebrafish are less plastic

Zebrafish have been used in medical research since at least the 1970’s as their anatomy, physiology, as well as genetics are similar to humans. Other advantages to studying zebrafish is that they are inexpensive to raise, and they reproduce well in captivity. The ability to adjust one’s physiology in response to varying environments is called plasticity. An organism may encounter any number of environmental fluctuations (light/dark, temperatures, predation risk, noise, […]

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Are declines in food availability to blame for the menu change?

Yesterday, we marveled over the recent sightings of two killer whales targeting sharks off the coast of South Africa. The recent uptick in shark hunting has scientists wondering how the loss of great white sharks will impact the ecosystem. But it also has some wondering why the orcas are targeting so many sharks when their diets typically consist of a variety of fish and marine mammals.   Clues may lie […]

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Killer whales scare off sharks

A pair of killer whales, nicknamed ‘Port and Starboard’, has been terrorizing great white sharks. In recent years as many as 8 sharks (possibly more) have succumbed to the pair. Many of the discovered sharks were missing their fatty liver and sometimes their heart. While orca hunting escapades are not particularly newsworthy, the antics of these orcas have attracted the attention of scientists as they are altering the ecosystem. Once […]

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Under pressure: One way our bodies regulate blood pressure

Did you know that blood vessels come fully equipped with the ability to help regulate blood pressure? This is possible because of smooth muscle cells that wrap around blood vessels (see image above). Because they wrap around the inner layers of the blood vessel, when these cells contract, the lumen od the blood vessel becomes narrow and increases blood pressure. When they relax, the blood vessels widen thereby lowering blood […]

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Humans do it, cats do it, dogs do it…why can’t rodents or rabbits do it?

Did you know that rodents and rabbits are not able to vomit? This was certainly news to me. So, I had to find out more… First, let’s talk about the difference between retching and vomiting. During retching (or dry heaves), the diaphragm and abdominal muscles contract, which helps increase pressure within the stomach (and prepare the contents for expulsion). Vomiting also involves contractions of the diaphragm, abdominal as well as […]

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Buoyancy and Balance

Existing species of coelacanths (pictured above) are descendants of a group of fish that existed about 410 million years ago, during the early Devonian period. They can be found in the Western Indian Ocean off the coast of Indonesia. These fish are really interesting because they have very low metabolic rates. In fact, their metabolism is among the lowest of any other existing vertebrate. Even sloths are jealous of their […]

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Turning up the heat

There are several ways to stay warm on a cold day. If you are human, you can turn up the heat in your home, put on a sweater, snuggle, and even produce body heat through shivering as well as non-shivering metabolic pathways – although the ability to produce heat metabolically typically declines with aging. If you are a small mammal, turning up the heat or putting on a sweater are […]

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Nitrites and noses

If you have ever had a fish tank, you may be familiar with monitoring ammonia levels in the water. Ammonia levels can rise due to overcrowding, overfeeding, as well as fish waste. Nitrite levels in the water also require monitoring as nitrite can bind to hemoglobin, which prevents oxygen from binding. In effect, by preventing oxygen from binding, the fish can succumb to hypoxia. Hannah Hughes, a graduate student working […]

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More than milk

Prolactin is an important pituitary hormone in mammals that works with oxytocin to provide milk for offspring. It also plays a role in promoting bonding between new mothers and their offspring. But did you know that non-mammalian vertebrates have prolactin too? Considering non-mammalian organisms do not have mammary glands, it must serve a different purpose in these animals.   As it turns out, prolactin is very important in the ability […]

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