Life Lines by Dr. Dolittle

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Archive for January 2017

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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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First known case of zebra shark switching to asexual reproduction

The story begins in 1999 when Leonie, a zebra shark (aka a leopard shark in Australia), was captured from the wild. In 2006 she was transferred to Reef HQ Aquarium in Queensland, Australia where she met her mate. By 2008, she had started laying eggs and the pair had multiple litters of offspring through sexual reproduction. After her mate was removed from the tank to prevent further breeding, she has shared the tank with […]

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Ammonia tolerance of goldfish

Liver failure or congenital defects can lead to a build-up of ammonia in the brain of mammals resulting in life-threatening swelling, convulsions and comas. For goldfish (Carassius auratus), environmental exposure to ammonia causes reversible swelling of the brain. In a new study published in the American Journal of Physiology – Regulatory, Integrative and Comparative Physiology, researchers wanted to explore how the fish were able to accomplish this. They exposed goldfish to high […]

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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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