Meet the amazing and 'ew'-inspiring Pacific hagfish

dr. dolittle — Sat, 29 Jul 2017 22:21:08 +0000

Image via NOAA/Flickr

Pacific hagfish (Eptatretus stoutii), aka "slime eels", are primitive fish that occupy burrows on the ocean floor. Like earthworms, they have 5 hearts. They have no true eyes, no jaws, nor do they have a stomach. They locate their meals through great senses of smell and touch. In addition to small invertebrates, they are known for consuming carrion that fall to the ocean floor. By consume, I mean burrow into the decomposing carcasses and eating them from the inside out. Ew. Given their dietary habits, it is no surprise they are regularly exposed to little to no oxygen and high ammonia levels as they burrow into carcasses. While some fish suffer from brain swelling, coma and even death with exposure to high ammonia levels, hagfish are remarkably tolerant of ammonia. A recent study published in the American Journal of Physiology - Regulatory, Integrative and Comparative Physiology, discovered what makes hagfish so tolerant. As it turns out, hagfish can get rid of excess ammonia by excreting it through special transporters in their gills and skin.

That's not all that comes from their skin. Like Slimer, from the Ghostbusters, hagfish have glands on their bodies that produce slime to help them escape predators. It is thought that the slime can gum up their attacker's gills. Hagfish slime contains thousands of very skinny, and very strong, long protein threads. Some researchers are exploring how these threads may be woven to produce strong fabrics or even artificial tissues.

Just fascinating.

Sources:

Wired

dr. dolittle Sat, 07/29/2017 - 18:21

Ammonia tolerance of goldfish

dr. dolittle — Tue, 17 Jan 2017 00:01:52 +0000

Ammonia tolerance of goldfish

Image of goldfish from Wikipedia

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 levels of ammonia for 72 hours which, like mammals, caused oxidative stress and swelling of the brain. What they also noticed, however, is that the goldfish increased the activities of several antioxidants in their brains to combat the oxidative stress and reverse some of the swelling. This protective mechanism may help the fish to thrive in otherwise uninhabitable waters for predators or competing fish. I wonder if my mother knew about this when she flushed Goldie my goldfish down the toilet by accident so many years ago...

For humans, this research may lead to new ways to help protect tissues from potential oxidative damage resulting from liver failure or congenital defects.

Source:

DFJ Lisser, ZM Lister, PQH Pham-Ho, GR Scott, MP Wilkie. Relationship between oxidative stress and brain swelling in goldfish (Carassius auratus) exposed to high environmental ammonia. American Journal of Physiology - Regulatory, Integrative and Comparative Physiology. 312(1): R114-R124, 2017. DOI: 10.1152/ajpregu.00208.2016

dr. dolittle Mon, 01/16/2017 - 19:01