Posts Tagged ‘Frog’

Poison frogs produce toxins that plow down a nervous system. Get a tiny amount of the poison in your system, and you’re in for trouble. They manage this by storing up toxins ingested from their prey. And yet the frogs themselves are totally immune. How does a frog that stores and dispenses poison manage to avoid negative effects from its own lethal toxins? It’s actually a complex evolution of amino acid replacements, according to a recent study in the journal Science.

The frog neurotoxin epibatidine binds to acetylcholine receptors, which makes it difficult for frogs to gain a resistance to epibatidine. But one amino acid replacement that has evolved in three clades of poison frogs allows the amphibians a lower sensitivity to epibatidine, while still maintaining receptor functionality.

The study’s authors “found that the single amino acid change common to all the poison frogs made the receptor less sensitive to the toxin, yet also rendered it less responsive to acetylcholine, its endogenous ligand,” the Scientist magazine notes. “But the different combinations of additional amino acid substitutions observed in two of the groups of poison frogs recovered the receptor’s function, suggesting that these mutations compensate for the cost associated with avoiding self-poisoning.”

In other words, poison frogs are immune to the toxins because they have been able to reorganize how their nervous system works using amino acid replacements.

https://www.mnn.com/earth-matters/animals/blogs/why-dont-poison-dart-frogs-poison-themselves

Advertisements

by Katie Forster

Powerful new remedies for the flu could be created using a molecule found in frog slime after scientists discovered it destroys the virus.

Mucus from a colourful species of Indian frog contains a compound that kills influenza, according to a new study published in the scientific journal Immunity.

The frog, called hydrophylax bahuvistara, was discovered in 2015. It is a type of fungoid frog that lives in the forests of south west India and has a striking orange stripe on its upper body.

Researchers captured the frog and collected secretions from its skin after delivering a mild electric shock. They then released the amphibians back into the wild and studied the chemicals in their slime.

Joshy Jacob, a scientist at Emory University in Atlanta, who led the study, said they managed to isolate a small structure called a peptide that kills the flu virus but leaves healthy tissue intact.

“This peptide kills the viruses. It kind of blows them up,” Dr Jacob, an associate professor in microbiology, told NBC News. “There’s no collateral damage,”

Dr Jacob and his team decided to name the compound urumin – after an Indian sword called an urumi with a flexible blade that acts like a whip, used in martial arts from the southern city of Kerala.

Mice vaccinated with urumin were protected against a lethal amount of swine flu virus, also known as Influenza A of H1, which caused a pandemic in 2009.

It’s likely the frog produces the flu-fighting substance in its slime by coincidence, as one of a number of compounds that guard against harmful bacteria and fungi.

The scientists hope their discovery will lead to the development of new drugs to stop outbreaks of influenza, which is highly contagious and can be deadly, especially for the elderly and very young.

They will also continue the search for other frog slime compounds that could be used to treat other viral infections such as hepatitis, HIV and Zika.

The difficulty is finding molecules that attack flu but do not harm healthy cells as well – of the four peptides found in the hydrophylax bahuvistara mucus, only urumin did not kill red blood cells.

“In the beginning, I thought that when you do drug discovery, you have to go through thousands of drug candidates, even a million, before you get one or two hits. And here we did 32 peptides, and we had four hits,” said Dr Jacob.

Urumin is thought to target a viral surface protein called haemagluttinin – the H in H1.

“The virus needs the haemagglutinin to get inside our cells,” said Dr Jacob. “What this peptide does is it binds to the haemagglutinin and destabilises the virus. And then it kills the virus.”

http://www.independent.co.uk/news/health/frog-slime-flu-virus-compound-blows-up-kills-influenza-hydrophylax-bahuvistara-immunity-a7690141.html