Snakebite antivenom discovery in American opossums


This video from the USA says about itself:

Virginia Opossum Family

12 July 2012

A short video clip of a Virginia Opossum family in wildlife rehabilitation at Evelyn’s Wildlife Refuge, Virginia Beach, VA. The mother Opossum came into care with an eye injury and front feet injuries.

From the East County Magazine in the USA:

SNAKEBITE ANTIVENOM SOURCE FOUND IN OPOSSUMS

By Miriam Raftery

April 5, 2015 (San Diego’s East County) – Opossums aren’t typically thought of as a powerhouse in the animal kingdom. The term “playing possum” after all refers to one way opossums react to predators –by playing dead. But it turns out that opossums have a peptide that gives them a natural immunity to snakebites and other toxins – and now scientists are working to harness it to create anti-venoms.

Scientists have isolated the peptide, and in lab tests with mice exposed to venom, those opossum peptides proved effective against Western diamondback rattlers and Russell’s vipers from Pakistan. The results offer hope that a universal antivenom could be developed to counter the poisonous effects of snakebites from multiple species, National Geographic reports.

That’s big news, since worldwide, about 421,000 poisonous snake bites occur each year, and 20,000 deaths result, according to International Society on Toxicology. Human testing is next on the horizon.

Moreover, Newswise reporters, scientists found they could reproduce the peptide from E-coli bacteria, meaning it can be replicated cheaply and easily—no opossums need to be harmed in the process. Unlike standard snakebite anti-venoms, this one has thus far produced no serious side effects such as wheezing, rash or rapid heartbeat.

The anti-venom may even prove effective against other forms of toxins, since opossums also have a natural resistance to poisonous scorpions and some forms of toxic plants as well.

The results were presented in late March at the National Meeting and Exposition of the American Chemical Society in Denver.

The opossum, which resembles a large rat, is a marsupial tracing its origins back 65 million years, around the time dinosaurs went extinct. But only now have we learned a key secret to its survival against threats that kill many other animals.

So the next time you see a lowly opossum hanging by its tail from a fence or waddling across a road, remember – this ancient animal just may hold the key to saving your life if you’re ever bitten by a snake.

Adder research in the Netherlands, video


This Dutch video is about adder research in the Netherlands.

Adder mating season: here.

2015, Year of the Adder


This video from South Yorkshire in England is called Adders mating (Vipera berus).

2015 is not just the Year of Vincent van Gogh. And the Year of the Penny Bun for mycologists. And the Year of the Goat in the Chinese calendar (starting on 19 February). And the Year of the Badger.

The Dutch RAVON herpetologists have decided that 2015 is the year of the only venomous snake in the Netherlands: the adder. They hope that this year there will be more measures for a better environment for adders, like tunnels enabling them to cross roads.

See also here.

Dutch amphibians and reptiles in winter


This video from France shows a grass snake and an adder together.

Because winter weather has been relatively mild so far in January, some reptiles and amphibians in the Netherlands are already active, Dutch RAVON herpetologists report.

From 1 till 19 January 2015 were seen: two adders; four slow worms; eight Alpine newts; fifteen great crested newts; twenty smooth newts; eighteen common toads; 35 common frogs; one moor frog; six edible frogs; one red-eared slider turtle; and one loggerhead sea turtle.

Biodiversity, including small predators such as dragonflies and other aquatic bugs that attack and consume parasites, may improve the health of amphibians, according to a team of researchers. Amphibians have experienced marked declines in the wild around the world in recent decades, the team added: here.

Dutch reptiles use life-saving tunnel


This video is about reptiles in France and Tunisia.

In 2009, herpetologists designed a special wildlife corridor for reptiles and amphibians, a ‘herpetoduct‘ for nature reserve Elspeetsche Heide in the Netherlands.

It is a tunnel under the N310 motorway and a bicycle track, preventing crossing animals from being killed by traffic.

Research at various times in 2012-2014 proves much wildlife, especially lizards, use the tunnel. 16 viviparous lizards used the tunnel. Once, even at least five young viviparous lizards were born in the tunnel. Other species: four sand lizards; one slow worm; two adders; one moor frog; one European toad; one Alpine newt. Also, one smooth snake was seen.

Results of the research were published in the Zeitschrift für Feldherpetologie.

How some snakes became venomous, new research


This video is called The Evolution of Venom – Who is The Most Poisonous? [Full Documentary]

From the University of Texas at Arlington in the USA today:

Team proposes new model for snake venom evolution

17 hours ago

Technology that can map out the genes at work in a snake or lizard‘s mouth has, in many cases, changed the way scientists define an animal as venomous. If oral glands show expression of some of the 20 gene families associated with “venom toxins,” that species gets the venomous label.

But, a new study from The University of Texas at Arlington challenges that practice, while also developing a new model for how snake venoms came to be. The work, which is being published in the journal Molecular Biology and Evolution, is based on a painstaking analysis comparing groups of related genes or “gene families” in tissue from different parts of the Burmese python, or Python molurus bivittatus.

A team led by assistant professor of biology Todd Castoe and including researchers from Colorado and the United Kingdom found similar levels of these so-called toxic gene families in python oral glands and in tissue from the python brain, liver, stomach and several other organs. Scientists say those findings demonstrate much about the functions of genes before they evolved into venoms. It also shows that just the expression of genes related to venom toxins in oral glands of snakes and lizards isn’t enough information to close the book on whether something is venomous.

“Research on venom is widespread because of its obvious importance to treating and understanding snakebite, as well as the potential of venoms to be used as drugs, but, up until now, everything was focused in the , where venom is produced before it is injected,” Castoe said. “There was no examination of what’s happening in other parts of the snake’s body. This is the first study to have used the genome to look at the rest of that picture.”

Learning more about venom evolution could help scientists develop better anti-venoms and contribute to knowledge about gene evolution in humans.

Castoe said that with an uptick in genetic analysis capabilities, scientists are finding more evidence for a long-held theory. That theory says highly toxic venom proteins were evolutionarily “born” from non-toxic genes, which have other ordinary jobs around the body, such as regulation of cellular functions or digestion of food.

“These results demonstrate that genes or transcripts which were previously interpreted as ‘toxin genes’ are instead most likely housekeeping genes, involved in the more mundane maintenance of normal metabolism of many tissues,” said Stephen Mackessy, a co-author on the study and biology professor at the University of Northern Colorado. “Our results also suggest that instead of a single ancient origin, venom and venom-delivery systems most likely evolved independently in several distinct lineages of reptiles.”

Castoe was lead author on a 2013 study that mapped the genome of the Burmese python. Pythons are not considered venomous even though they have some of the same genes that have evolved into very toxic venoms in other species. The difference is, in highly venomous snakes, such as rattlesnakes or cobras, the venom gene families have expanded to make many copies of those shared genes, and some of these copies have evolved into genes that produce highly toxic venom proteins.

“The non-venomous python diverged from the snake evolutionary tree prior to this massive expansion and re-working of venom gene families. Therefore, the python represents a window into what a snake looked like before venom evolved,” Castoe said. “Studying it helps to paint a picture of how these gene families present in many vertebrates, including humans, evolved into deadly toxin encoding genes.”

Jacobo Reyes-Velasco, a graduate student from Castoe’s lab, is lead author on the new paper. In addition to Castoe and Mackessy, other co-authors are: Daren Card, Audra Andrew, Kyle Shaney, Richard Adams and Drew Schield, all from the UT Arlington Department of Biology; and Nicholas Casewell, of the Liverpool School of Tropical Medicine.

The paper is titled “Expression of Venom Gene Homologs in Diverse Python Tissues Suggests a New Model for the Evolution of Snake Venom.” It is available online here.

The research team looked at 24 gene families that are shared by pythons, cobras, rattlesnakes and Gila monsters, and associated with venom. The traditional view of venom evolution has been that a core venom system developed at one point in the evolution of snakes and lizards, referred to as the Toxicofera, and that the evolution of highly venomous snakes, known as caenophidian snakes, came afterward. But little explanation has been given for why evolution picked just 24 genes to make into highly toxic venom-encoding genes, from the 25,000 or so possible.

“We believe that this work will provide an important baseline for future studies by venom researchers to better understand the processes that resulted in the mixture of toxic molecules that we observe in venom, and to define which molecules are of greatest importance for killing prey and causing pathology in human snakebite victims,” Casewell said.

When they looked at the python, the team found several common characteristics among the venom-related gene families that differed from other genes. Compared with other python gene families, venom are “expressed at lower levels overall, expressed at moderate-high levels in fewer tissues and show among the highest variation in expression level across tissues,” Castoe said.

“Evolution seems to have chosen what genes to evolve into venoms based on where they were expressed (or turned on), and at what levels they were expressed,” Castoe said.

Based on their data, the new paper presents a model with three steps for venom evolution. First, these potentially venomous genes end up in the oral gland by default, because they are expressed in low but consistent ways throughout the body. Then, because of natural selection on this expression in the oral gland being beneficial, tissues in the mouth begin expressing those genes in higher levels than in other parts of the body. Finally, as the venom evolves to become more toxic, the expression of those genes in other organs is decreased to limit potentially harmful effects of secreting such toxins in other body tissues.

The team calls its new model the Stepwise Intermediate Nearly Neutral Evolutionary Recruitment, or SINNER, model. They say differing venom levels in snakes and other animals could be traced to the variability of where different species, or different genes within a species, are along the continuum between the beginning and end of the SINNER model.

Castoe said the next step in the research would be to examine the genome of highly venomous snakes to see if the SINNER model bears out. For now, he and the rest of the team hope that their findings about the presence of venom-related in other parts of the python change some thinking on what species are labeled as venomous.

“What is a venom and what species are venomous will take a lot more evidence to convince people now,” Castoe said. “It provides a brand new perspective on what we should think of when we look at those oral glands.”