News... News... News... (en anglais)

[askook 0]

Rattler's reputation takes a toxic turn for the worse

Experts suspect species is becoming deadlier

With warming weather comes the return of rattlesnakes and renewed reports that one species of the slithering reptile may be biting more people and becoming more dangerous.

In recent years, some doctors and toxicologists in Southern California and across the Southwest have reported anecdotal evidence of an increase in snakebite cases, with more patients suffering extreme – sometimes fatal – consequences.

Last summer, San Diego Poison Control officials said the recorded number of “unusually powerful” snakebites had increased for the second consecutive year. Media attention has fanned the furor, most recently an article in the current issue of Scientific American that suggests the venom of the southern Pacific rattlesnake, a common species in San Diego County, is becoming “extratoxic.”

That's bad news for potential bite victims and arguably worse news for rattlesnakes, but some herpetologists and snake experts question whether the phenomenon is real.

Each year, the San Diego division of the California Poison Control System records 40 to 60 rattlesnake bites in San Diego County, said Dr. Richard Clark, a toxicologist at the University of California San Diego and medical director of the local poison control center. In 2004, the poison control system recorded 42 rattlesnake bites to humans in the county. In 2005, there were 45; in 2006, 54; in 2007, 47; and last year, 41.

The real number is higher, Clark said, because snakebites are not among cases that doctors are required to report. Clark said he believes that locally, one or two snakebites in 2008 were fatal.

In the United States, according to the Centers for Disease Control and Prevention, there are roughly 7,000 reported venomous snakebites each year, 15 of which on average prove fatal.

Clark said the number of snakebites varies with shifting environmental conditions. Wildfires, for example, can substantially affect rattlesnake habitat, reproduction rates and prey availability. He predicted that the annual number of rattlesnake bites will trend upward “as we continue to build and expand into East County and snake habitat.”

San Diego County is home to four species of rattlesnake: the speckled, the red diamond, the sidewinder and the southern Pacific, which is a subspecies of the western rattlesnake and the most abundant rattler in the region.

It's the southern Pacific rattlesnake that's generating headlines and concern, with speculation that the species is evolving and expanding into a more dangerous animal. To some degree, scientists say, there are reasons to worry.

First, southern Pacifics are more widely distributed than other indigenous rattlesnakes. They live in diverse habitat from the beaches to the mountains, and they are tolerant of disturbed, developed areas.

“Southern Pacific rattlesnakes thrive where people prefer to live, so people encounter them relatively frequently,” said Dr. Sean Bush, a professor of emergency medicine at Loma Linda University and a snake researcher.

Second, the snakes appear to be more easily annoyed than other species and are more likely to defend themselves aggressively. Clark described them as having “nasty dispositions” and more inclined than other rattlers to bite before retreat.

Bush called them “people-biting snakes.”

It's the bite, of course, that concerns doctors, scientists and potential victims. Rattlesnake venom is a lethal cocktail of toxins that quickly causes significant tissue damage and hemorrhaging. The bitten prey weakens and dies, and then the snake consumes it.

In humans, an ordinary rattlesnake bite produces initial swelling and bruising around the wound, but quick treatment and new antivenins mean rattlesnake bites are rarely fatal.

There is research to indicate that the venom of at least some southern Pacific rattlesnakes contains an additional deadly ingredient: a fast-acting neurotoxin that affects breathing and muscle control. (A telling symptom of a southern Pacific bite is rapid, uncontrollable muscle twitching.)

A neurotoxin is also present in the Mohave rattlesnake, a deadlier, desert-dwelling species found primarily in Arizona and Mexico, though part of its range reaches into eastern San Diego County.

Some researchers have speculated that interbreeding with Mohave rattlesnakes has produced a deadlier version of the southern Pacific. Richard Dart, director of the Rocky Mountain Poison and Drug Center in Denver, said it's possible. “If they're rattlesnakes, they'll interbreed. I've seen it in the lab, though it's probably not something that happens in nature every mating season.”

William Hayes, a biologist and snake researcher at Loma Linda University, is more skeptical. He dismisses the idea that southern Pacific rattlesnakes are naturally evolving a more toxic venom. The majority of western rattlesnakes lack neurotoxins in their venom, he said. If some southern Pacific rattlesnakes do in fact have them, it's likely to be an unidentified toxin.

Bush suggests the phenomenon may be an example of convergent evolution.

“That is, an animal develops a similar trait because it utilizes it for a similar task,” Bush said. “Sort of like giraffes and brontosauruses both having long necks, probably to feed on leaves high in trees.”

On one thing all of the researchers agree: Size matters in snakebites. Adult victims tend to fare better than children because of greater body mass. And the bigger the snake, the worse its bite.

“I don't know where the myth about baby rattlers being more dangerous came from,” said Dr. Roy Johnson, an Escondido-based physician and herpetologist. “The key is how much venom is injected, and a big snake injects a lot more venom than a small snake.”

Anecdotal reports of nastier snakebites may be due to a proportionate increase in big snakes. Hayes said chronic drought conditions in Southern California may have reduced reproductive rates among rodents and other small mammals, which are the southern Pacific's preferred prey.

As a result, the rattlesnake's reproductive rate has also declined, reducing the number of juvenile snakes. “We may well be seeing a shift toward more bites being inflicted by larger rattlesnakes simply because smaller snakes may now be disproportionately few,” Hayes said. Southern Pacific rattlesnakes can grow up to 4 feet in length.

Snakebite data suggest big snakes usually bite big people. Children tend to be bitten by small rattlesnakes they stumble upon inadvertently. Adults are more often bitten by rattlesnakes they try to pick up.

“If anything, we can expect the escalating emphasis on snakes in nature television programming to inspire more people to make dumb decisions about handling venomous snakes,” Hayes said. “We might be seeing a shift in the demography of snakebite victims, with more adult men, many under the influence of alcohol, getting bitten by snakes they should not have been messing with.”

Johnson, the Escondido physician who has treated hundreds of snakebite victims over 30 years, agreed: “Mostly people get bitten because they tried picking up a snake, because they weren't smart enough to know better.”
Source:http://www3.signonsandiego.com/stories/2009/apr/20/1n20rattlers223712-rattlers-reputation-takes-toxic/

[askook 0]

Transcriptomic basis for an antiserum against Micrurus corallinus (coral snake) venom

Micrurus corallinus (coral snake) is a tropical forest snake belonging to the family Elapidae. Its venom shows a high neurotoxicity associated with pre- and post-synaptic toxins, causing diaphragm paralysis, which may result in death.

In spite of a relatively small incidence of accidents, serum therapy is crucial for those bitten. However, the adequate production of antiserum is hampered by the difficulty in obtaining sufficient amounts of venom from a small snake with demanding breeding conditions.

In order to elucidate the molecular basis of this venom and to uncover possible immunogens for an antiserum, we generated expressed sequences tags (ESTs) from its venom glands and analyzed the transcriptomic profile. In addition, their immunogenicity was tested using DNA immunization.

Results: A total of 1438 ESTs were generated and grouped into 611 clusters. Toxin transcripts represented 46% of the total ESTs.

The two main toxin classes consisted of three-finger toxins (3FTx) (24%) and phospholipases A2 (PLA2s) (15%). However, 8 other classes of toxins were present, including C-type lectins, natriuretic peptide precursors and even high-molecular mass components such as metalloproteases and L-amino acid oxidases.

Each class included an assortment of isoforms, some showing evidence of alternative splicing and domain deletions. Five antigenic candidates were selected (four 3FTx and one PLA2) and used for a preliminary study of DNA immunization.

The immunological response showed that the sera from the immunized animals were able to recognize the recombinant antigens.

Conclusions: Besides an improvement in our knowledge of the composition of coral snake venoms, which are very poorly known when compared to Old World elapids, the expression profile suggests abundant and diversified components that may be used in future antiserum formulation. As recombinant production of venom antigens frequently fails due to complex disulfide arrangements, DNA immunization may be a viable alternative.

In fact, the selected candidates provided an initial evidence of the feasibility of this approach, which is less costly and not dependent on the availability of the venom.
Source:http://7thspace.com/headlines/305366/transcriptomic_basis_for_an_antiserum_against_micrurus_corallinus_coral_snake_venom.html

[askook 0]

Venom cures

Local man claims there is a poisonous cure for cancer
SENECA — Next time you see a Copperhead snake in your backyard, leave it alone. Not because it has the potential to bite you and cause severe damage, but because one day, it might just save your life.

Joel LaRocque, Seneca resident and avid snake handler and enthusiast, claims the answer to cancer treatment lies in the jaws of these reptiles.

LaRocque was bitten and spared by a deadly Cottonmouth in the late 1960s. He has been intrigued and awed by snakes ever since. His admiration has grown to immeasurable lengths.

Now, he works with numerous cancer laboratories across the world as he freeze dries and ships off Copperhead venom that, one day, could be used to stop the spread of cancer cells and even shrink tumors, he said.

“In the late 1990s, Japanese scientists found that Copperhead venom carried a tiny protein called ‘Contortrostatin,’” he said. “Then in early 2000, scientists at Loma Linda University in California found that this protein can actually halt the spread of cancer cells with early detection.”

So the question is … why on earth aren’t scientists pushing to get this treatment into hospitals and homes around the world?

“It’s the money issue and all the legalities that come along with new treatments,” he said. “Especially ones such as this, that would take so much money away from other treatments like radiation and chemotherapy,” LaRocque argues.

Like LaRocque, Bill Haast, a laboratory researcher at the Miami Serpentarium who has worked most of his 95 years around venomous snakes and understands the potential for venom to “heal,” has been bitten more than 170 times.

To ward off the dangers of their occupation, both men inject themselves with a cocktail of venom once a month to build up antibodies.

“The pain is incredible, but it has really helped me stay healthy and safe from probable snake bites,” LaRocque said.

In the end, he said, it pains him more than anything to know there is an up and coming treatment that could save lives, but isn’t being utilized.

“Sometimes it is hard to swallow that money is so much more important than saving lives,” he said. “But that’s the system that has been installed, and there isn’t much we can do about it.”

After his many discussions with laboratory workers and researchers, LaRocque said he understands the process that needs to be followed when developing a possible new cure, but he can't help but think of the 40,000 or more women who lose their lives to breast and other cancers each year.

“These snakes could literally save their lives,” he said. “It’s just a shame to know you are holding a key to health
but this feasible treatment won't hit the shelves for another 25 years or more.”

And even though LaRocque and his wife, Janice, continue to care for snakes and hope to benefit cancer victims in the future, they don’t have nearly the number of slithering pets they once had in Louisiana.

“We were wiped out by Katrina,” he said. “We lost hundreds of our snakes, and it absolutely broke our hearts. We moved to Oconee County just under a year ago and we hope to make a difference nationwide from the beautiful Upstate.”

LaRocque also wants to spread the overall knowledge of snakes to youth in the community.

“We would love to travel to schools and show these kids what to look out for, which snakes to avoid and how to identify them. We just want to give back to the community and I think students and teachers alike would benefit from our presentation.”

"The cure to breast cancer lies in these Copperheads," claims Joel LaRocque


This Copperhead is being "milked" for its venom. Even though no one has died from a Copperhead bite, these snakes can cause extreme nerve and tissue damage once they bite and inject venom.

Source:http://www.upstatetoday.com/news/2009/mar/10/venom-cures/

[askook 0]

Cannibalism Among Rattlesnakes Helps Females To Recover After Birth

Spanish, American and Mexican researchers have produced the first quantitative description of cannibalism among female rattlesnakes (Crotalus polystictus) after monitoring 190 reptiles. The study has shown that these animals ingest on average 11% of their postpartum mass (in particular eggs and dead offspring) in order to recover energy for subsequent reproduction.

The lack of information about cannibalism in rattlesnakes (Crotalus polystictus) led researchers to start a study in 2004, which they continued for three years in central Mexico, where this species is endemic. They measured "cannibalistic behaviour" among 190 females, which had 239 clutches of eggs, and determined that this phenomenon is justified by "enabling the mother to recover and regain strength".

"A cannibal rattlesnake female can recover lost energy for reproduction without having to hunt for food, a dangerous activity that requires time and expends a great deal of energy," Estrella Mociño and Kirk Setser, lead authors of the study and researchers at the University of Granada, along with Juan Manuel Pleguezuelos, tell SINC.

The study, published in the latest issue of the journal Animal Behaviour, shows that cannibalism in this species is an evolutionary result of its feeding behaviour, since its prey is dead for some time before being eaten by the snake. "Viperids in general are prepared to eat carrion, and for this reason it is not so strange that they consume the non-viable sections of their clutches after going through the great energy expenditure caused by reproduction," says Mociño.

The research team say this behaviour can be explained by four biological factors - the day of the birth (females that give birth at the end of July are more likely to be cannibals, since they have less time to feed and prepare themselves to reproduce again), the proportion of dead babies per clutch, the level of maternal investment (the larger the brood, the greater the chance that it will contain non-viable elements, which she will eat), and stress caused by being in captivity (the researchers maintained the females in captivity for an average of 21 days).

Of all the females, 68% consumed part or all of their dead offspring, and 83% of these ate them all, and waited little time to do so (around 16 hours), although some ate them "immediately after giving birth", adds Mociño. The rest (40%) of the females "did not display cannibalistic behaviour".

According to the scientists, cannibalism is "not an aberrant behaviour, and is not an attack on the progeny", since it is not the same as parricide or infanticide as it does not involve live elements. It simply recovers some of what the snake invested in the reproduction process, and prepares it to reproduce once again.

Snakes can distinguish between dead and live offspring

The scientists showed there was a low risk of the snakes eating healthy offspring, which look very similar to dead ones for the first two hours after emerging from their membranes. During the study, only one female ate live babies.

"In comparison with mammals or birds, snakes are not as maternal, but the study shows that they also display behaviour that has evolved, and that helps the female and her offspring to reproduce and grow successfully," say Mociño and Setser.

Crotalus polystictus is categorised as a "threatened species" according to the Official Mexican Regulations on protection of native species of wild flora and fauna in Mexico. Limited habitat, urban expansion and the growth of agriculture are the main threats to the snake.

To date, the scientists have marked more than 2,000 individuals of this species, which range in length on average from 50cm to 90 cm, and which display different survival strategies from many other rattlesnakes in the north of Mexico and the United States.

This reptile has a very rapid reproduction rate, suggesting that it is experiencing a high death rate caused by external factors. As well as contributing to scientific knowledge about animal cannibalism from an evolutionary perspective, the scientists hope that publicising these results will "lead to human beings being less aggressive towards these snakes".
Source:http://www.sciencedaily.com/releases/2009/02/090219095533.htm

Article de référence:
Mociño-Deloya et al. Cannibalism of nonviable offspring by postparturient Mexican lance-headed rattlesnakes, Crotalus polystictus. Animal Behaviour, 2009; 77 (1): 145

[paul371 0]

Of cours...
Bonne chance a ceux qui lisent l'anglais contrairement a moi

[Wolfen1 0]

Google est ton ami

http://translate.google.fr/translate?js=n&prev=_t&hl=fr&ie=UTF-8&u=http%3A%2F%2Fwww3.signonsandiego.com%2Fstories%2F2009%2Fapr%2F20%2F1n20rattlers223712-rattlers-reputation-takes-toxic%2F&sl=en&tl=fr&history_state0=
http://translate.google.fr/translate?js=n&prev=_t&hl=fr&ie=UTF-8&u=http%3A%2F%2F7thspace.com%2Fheadlines%2F305366%2Ftranscriptomic_basis_for_an_antiserum_against_micrurus_corallinus_coral_snake_venom.html&sl=en&tl=fr&history_state0=
http://translate.google.fr/translate?js=n&prev=_t&hl=fr&ie=UTF-8&u=http%3A%2F%2Fwww.upstatetoday.com%2Fnews%2F2009%2Fmar%2F10%2Fvenom-cures%2F&sl=en&tl=fr&history_state0=
http://translate.google.fr/translate?js=n&prev=_t&hl=fr&ie=UTF-8&u=http%3A%2F%2Fwww.sciencedaily.com%2Freleases%2F2009%2F02%2F090219095533.htm&sl=en&tl=fr&history_state0=

http://translate.google.fr/translate_t#

[Valko03 0]

Merci beaucoup Wolfen

[Marie-Laure1111 0]

C'est vrai que c'est beaucoup mieux avec une traduction.

Les traduction sont très comiques. Surtout sur le sujet du cannibalisme des crotales.

[askook 0]

Venomous Sea Snakes Play Heads Or Tails With Their Predators

In a deadly game of heads or tails venomous sea snakes in the Pacific and Indian Oceans deceive their predators into believing they have two heads, claims research published August 5 in Marine Ecology.

The discovery, made by Dr Arne Redsted Rasmussen and Dr Johan Elmberg, showed that Yellow-lipped Sea Kraits (Laticauda colubrina) use skin markings and behaviour patterns to fool predators into thinking their tail is a second head, complete with lethal venom.

There are over 65 species of sea snakes in the tropical waters of the Southern Hemisphere, ranging from Africa to the Gulf of Panama. Most spend their entire lives in the sea, inhabiting shallow water and are active predators, feeding on small fish found around coral reefs. All sea snakes have extremely potent venom which is among the most toxic known in all snake species.

When hunting for food sea snakes probe crevices and coral formations, temporarily forcing them to drop their guard to threats from the surrounding waters and making them highly vulnerable to attack. However, the Yellow-lipped Sea Krait has been found to twist its tail so that the tip corresponds with the dorsal view of the head, which combined with deceptive colouring, gives the illusion of having two heads and two loads of deadly venom.

Apart from the Yellow-lipped Sea Krait the ecology of sea snakes has largely gone understudied, due mainly to their off-shore and nocturnal behaviour. Yet, despite the number of behavioural studies devoted to this species, the discovery of this false-head-behaviour is a hitherto overlooked anti-predator adaptation.

The discovery was made while senior author Arne Redsted Rasmussen was diving off the coast of the Bunaken Island in Indonesia. A large Krait was followed for thirty minutes, swimming between corals and crevices hunting for food. Rasmussen was momentarily distracted by a second snake, but when looking back he was surprised to see the "head" was facing him while the tail probed the coral. Rasmussen's surprise grew when he saw a second head emerge from the coral instead of the expected tail. It was only when the snake swam away that the first head was clearly seen to be a paddling tail.

To build upon this discovery researchers examined 98 Sea Kraits from three major museum collections in Paris, Berlin and Copenhagen while also monitoring the behaviour of wild Sea Kraits in Solomon Islands during the Danish Galathea 3 Expedition. The research confirmed that all snakes of this species had a distinctive colouration pattern, with a bright yellow horseshoe marking on the tip of the head and the tail. The yellow was deeper than the colours on the rest of the body and the black colorations were much longer than the dark bands on the rest of the body, highlighting the similarity between the head and the tail.

The reason for this mixture of behaviour and coloration results from a developed defence strategy needed when the snake is probing for prey. Despite being extremely venomous sea snakes are susceptible to attack from several predators such as sharks, large bony fishes, and even birds.

"The value of such an adaptation is twofold; it may increase the chances of surviving predator attack by exposing a less 'vital' body part, but more importantly it may deter attack in the first place if attackers perceive the tail as the venomous snakes head," said Rasmussen.

Similar defence mechanisms have been discovered in lizards, and some land snakes have developed ingenious camouflage deterrent behaviour strategies, but this defence has never been associated with other lethally venomous predators such as sea snakes.

Traditionally the only evidence of a defence behaviour strategy in sea snakes has been documented in individual cases, when a snake was exposed to and aware of an imminent danger. This research is the first record of a combined false-head-behaviour and false-head-camouflage defence strategy used as instinct when a snake is hunting for food.

"It is intriguing that this discovery is observed in this species, as one of the key differences between the Yellow-lipped Sea Krait and other sea snakes is that they spend almost equal time on land and in the sea," said Rasmussen. "They therefore live in two worlds where two very different rules of survival apply. It remains to be confirmed whether Sea kraits use their sea defence tactic of motioning their tails when on land."
Source:http://www.sciencedaily.com/releases/2009/08/090805201539.htm

Traduction:
http://translate.google.com/translate?hl=fr&u=http%3A%2F%2Fwww.sciencedaily.com%2Freleases%2F2009%2F08%2F090805201539.htm