12 April 2018: Frogs Bouncing Back with Surprising Secretions

The Americans are basically now playing a game of chicken with Russia over Syria, the UK is hacking ISIS, and China wins the prize for World’s Top Executioner. Important stuff, but for your own sanity, take a break from the news for a few minutes for some positivity from the science desk.

Frog populations have been in decline for decades around the world, in many cases from to an epidemic of the deadly amphibian chytrid fungus. Some Central American frog populations are bouncing back in an unexpected way: they appear to be developing better skin resistance to the fungus pathogen.

The finding should assist frog conservation programs against future disease outbreaks, and could even aid the fights against some human diseases.

Associate Professor Louise Rollins-Smith at Vanderbilt University and her international team of researchers tracked the deadly fungus as it spread across central America from Costa Rica through Panama over ten years, to test the strength of the fungus’s pathogens over time. 

Frogs defend against the fungal disease by secreting chemicals through their skin. The researchers measured the effectiveness of this defence response in areas where the fungus was established, in recently invaded areas, and in regions free of the disease. 

The finding that some frog species were winning the battle against the fungus was a welcome discovery, but also surprising.

The scientists expected the frog populations to be recovering because the fungus was becoming less toxic. Instead, they found that the frogs themselves were the cause: where the disease was established, the frogs’ skin secretions were more effective against the fungus, compared with secretions from frogs in unaffected regions.

It isn’t clear yet whether this is because the frogs that survive the disease already had stronger defences, or if the frogs were chasing their secretions in response to the infection.

Understanding how these frog populations have adapted to the fungal epidemic can aid researchers in dealing with future disease outbreaks and assist conservation efforts. 

The research may also provide new pathways for understanding and treating human diseases. Past research by Professor Rollins-Smith’s team identified frog skin secretions could be effective against some human pathogens, such as HIV and gonorrhoea.

Source: https://www.eurekalert.org/pub_releases/2018-04/vumc-srd041118.php

Original Paper: http://science.sciencemag.org/content/359/6383/1517