Life Lines by Dr. Dolittle

Sponsored by the American Physiological Society

Hibernation and Hypoxia

Extreme tolerance of dehydration stress

Talk about an extreme animal. During the rainy season annual killifish, Austrofundulus limnaeus, lay eggs that are resistant to droughts. This is an important attribute for a fish that lives in temporary pools of water. The stress-resistant embryos within the eggs literally shut down their metabolism to survive months – possibly years without water. For many fish, exposure to air (and oxygen) can cause profound oxidative stress. Remarkably, this is […]

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Anoxia tolerance in goldfish

The reason mammals are not very good at tolerating hypoxic (i.e. low oxygen) environments, is because the brain relies heavily on oxygen for metabolism. It is so stingy, it uses about 20% of the oxygen in the body to make ATP. Without oxygen, the brain has to rely on glycolysis to make ATP and this process is not good at meeting the energy requirements of the neurons, ultimately resulting in […]

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Even the brainless need sleep

Most animals that we know of sleep. Sleep is very important for a healthy brain and our brains are important in regulating sleep. Interestingly, recent studies have shown that the cerebrospinal fluid actually washes out toxins from the brain when we get enough sleep at night. That “rinse cycle” so to speak is the brain’s way of staying healthy and is thought to prevent neurodegenerative diseases like Alzheimer’s. You may […]

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Extreme Fasting

While giant pandas roll in horse manure to stay warm in the winter (that’s a different story), other animals spend up to 8 months hibernating to conserve energy during times of reduced food availability and freezing temperatures. During their long winter’s nap, animals such as the Arctic ground squirrel and 13-lined ground squirrel go without food or water while at the same time avoiding muscle wasting – a rather impressive […]

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How a really long winter’s nap can impact sperm production

As winter approaches, hibernating animals will finalize their preparations for taking a ‘long winter’s nap’. These remarkable animals reduce their metabolism to help conserve energy at a time when environmental resources are scarce and considerable energy would otherwise need to be spent on just staying warm. For many species of hibernators, periodically entering this state of torpor allows them to reduce their energy needs by 90% compared to intermittent states […]

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Nature’s architects

Nature has already solved many problems that doctors, researchers, and architects are still trying to solve for humans. For example, some of our prior posts have talked about how some animals are resistant to developing cancer: Elephants Tasmanian devils Naked mole rats Other animals have developed special nano antibodies (nanobodies) to fight disease. Llamas While several are tolerant of very low oxygen levels in the environment, others are champions of […]

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Comparative Physiologist listed among the 100 most influential people of 2020

I was very excited to see Comparative Physiologist and astronaut Jessica Meir listed among Time’s 100 most influential people of 2020. Together with astronaut Christina Koch, who was also named among the top 100, the astronauts performed the first all-female spacewalk at the International Space Station in 2019. In all, the pair completed three spacewalks while aboard the International Space Station. It is hard to imagine how challenging it must […]

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Researchers discover cause of hearing loss in an underground dweller

Naked mole rats are rather extreme animals in many ways. As underground dwellers, they live in chronically hypoxic environments and are blind. These animals also age more slowly than other mammals and are resistant to developing cancer even though they are long-lived. Did you also know, they are hard of hearing? In a new study published in Current Biology, researchers have discovered the cause of their hearing loss. The inner […]

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We all need to get some shut eye

I have to confess that I have been spending way too much time binge watching shows about sharks during this year’s Shark Week on Discovery Channel. I know I should be getting 7 hours of sleep a night…but could watching just one more show be that bad? Speaking of sleep, I am reminded of a study that I read awhile back examining whether sharks and rays need sleep. This may […]

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Avian red blood cells produce hydrogen sulfide to maintain cell integrity and longevity

Birds have strange red blood cells, at least in comparison to mammals. While they both are responsible for transporting oxygen molecules throughout the body, avian red blood cells have mitochondria and a nucleus. Mammalian red blood cells, on the other hand, are missing a nucleus as well as organelles. By eliminating these structures, mammalian red blood cells are able to carry more oxygen molecules and fold more easily to fit […]

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