Lophiomys imhausi: The Poison Dart Rat

A poisonous surprise under the coat of the African crested rat

Authors:

Kingdon et al

Abstract:

Plant toxins are sequestered by many animals and the toxicity is frequently advertised by aposematic displays to deter potential predators. Such ‘unpalatability by appropriation’ is common in many invertebrate groups and also found in a few vertebrate groups. However, potentially lethal toxicity by acquisition has so far never been reported for a placental mammal. Here, we describe complex morphological structures and behaviours whereby the African crested rat, Lophiomys imhausi, acquires, dispenses and advertises deterrent toxin. Roots and bark of Acokanthera schimperi (Apocynaceae) trees are gnawed, masticated and slavered onto highly specialized hairs that wick up the compound, to be delivered whenever the animal is bitten or mouthed by a predator. The poison is a cardenolide, closely resembling ouabain, one of the active components in a traditional African arrow poison long celebrated for its power to kill elephants.

Component of Centipede Venom Blocks Pain Better Than Morphine

Researchers from the Chinese Academy of Sciences and The University of Queensland have discovered a [a component of ] venom from centipedes [is] capable of blocking pain more effectively than morphine!

[...]

Certain voltage-gated sodium channels (Nav1.7) are involved in the sensation of pain. In fact, people with mutated Nav1.7 channels are insensitive to pain. In a new study published in the Proceedings of the National Academy of Sciences, USA this week, researchers purified a component of the venom that can specifically inhibit Nav1.7 sodium channels. In the article, they describe it as “a highly selective inhibitor of Nav1.7 that is a more effective analgesic than morphine in rodent pain models.” Prior inhibitors of Nav1.7 channels have been less specific resulting in undesirable side effects. The good news about this new peptide is that it is more specific and according to the results of this study had no negative side effects on blood pressure, heart rate or motor function.

link.

Yikes! Venomous Raptors!

A group of University of Kansas researchers working with Chinese colleagues have discovered a venomous, birdlike raptor that thrived some 128 million years ago in China. This is the first report of venom in the lineage that leads to modern birds.

"This thing is a venomous bird for all intents and purposes," said Larry Martin, KU professor and curator of vertebrate paleontology at the Natural History Museum and Biodiversity Institute. "It was a real shock to us and we made a special trip to China to work on this."

The KU-China team's findings will be published in the early edition of the Proceedings of the National Academy of Sciences during the week of Dec. 21.

"We think it's going to make a big splash," said Martin.

The article's authors are Enpu Gong, geology department at Northeastern University in Shenyang, China, and researchers Martin, David Burnham and Amanda Falk at the KU Natural History Museum and Biodiversity Institute.

The dromaeosaur or raptor, Sinornithosaurus (Chinese-bird-lizard), is a close relative to Velociraptor. It lived in prehistoric forests of northeastern China that were filled with a diverse assemblage of animals including other primitive birds and dinosaurs.

"This is an animal about the size of a turkey," said Martin. "It's a specialized predator of small dinosaurs and birds. It was almost certainly feathered. It's a very close relative of the four-winged glider called Microraptor."

The venom most likely sent the victim into rapid shock, shrinking the odds of retaliation, escape or piracy from other predators while the raptor manipulated its prey.

"You wouldn't have seen it coming," said Burnham. "It would have swooped down behind you from a low-hanging tree branch and attacked from the back. It wanted to get its jaws around you. Once the teeth were embedded in your skin the venom could seep into the wound. The prey would rapidly go into shock, but it would still be living, and it might have seen itself being slowly devoured by this raptor."

The genus had special depressions on the side of its face thought by the investigators to have housed a poison gland, connected by a long lateral depression above the tooth row that delivered venom to a series of long, grooved teeth on the upper jaw. This arrangement is similar to the venom-delivery system in modern rear-fanged snakes and lizards. The researchers believe it to be specialized for predation on birds.

"When we were looking at Sinornithosaurus, we realized that its teeth were unusual, and then we began to look at the whole structure of the teeth and jaw, and at that point, we realized it was similar to modern-day snakes," Martin said.

More also at Not Exactly Rocket Science.

It'd be funny if the reason why there were so few large carnivores in the Maastrichtian was because the medium sized ones were all poisonous lil monsters...and pack hunters. Wow. Talk about a nasty combo!