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Ammonia tolerance of goldfish [Life Lines]

Source: http://scienceblogs.com/lifelines/2017/01/17/ammonia-tolerance-of-goldfish/

Image result for carassius auratus

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

Why orcas go through menopause [Life Lines]

Source: http://scienceblogs.com/lifelines/2017/01/13/why-orcas-go-through-menopause/

Image of an orca and her calf from Wikimedia Commons

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 of the family, so to speak, by making sure her offspring know where or when to find food. While this cooperative foraging behavior helps improve survival of the mother’s family, further offspring from the mother are 1.7 times more likely to die than her daughter’s offspring. This reproductive competition (or conflict) is thought to be a reason why the whales (and perhaps humans) evolved to go through menopause.

Source:

DP Croft, RA Johnston, S Ellis, S Nattrass, DW Franks, LJN Brent, S Mazzi, KC Balcomb, JKB Ford, MA Cant. Reproductive Conflict and the Evolution of Menopause in Killer. Current Biology. 27: 1-7, 2017. DOI: 10.1016/j.cub.2016.12.015

 

Is the California Drought Over? [Greg Laden's Blog]

Source: http://scienceblogs.com/gregladen/2017/01/13/is-the-california-drought-over/

My friend Peter Gleick tosses this question aside and informs us that there are actually better questions. Is California having a wet year? How does the snowpack look? Are the reservoirs filling up? Will the groundwater recharge? Will the forests in the Sierra recover with all this precip? Will farmers get all the water they want this year? Will a wet year help the endangered salmon? Will governor Brown cancel the drought declaration? Can Californians stop conserving water and throw some on their lawn?

It turns out that the answer to most of these questions is not what you would assume unless you know a lot about California’s water. Hey, this would make a great facebook quiz! “Only 50% of Californians can answer all of these questions correctly. Take the quiz now!”

Anyway, read this: Gleick: Is the drought over? Wrong question!