Showing posts with label China. Show all posts
Showing posts with label China. Show all posts

Friday, December 9, 2011

Odorrana Frogs as a Source for New Antibiotics

The  Chinese Odorrana tormota. Photo Credit 
Albert Feng
About 45 species of ranid frogs are currently recognized in the genus Odorrana, they inhabit high-gradient streams in Asia from Myanmar and Thailand and Malaya southward through the Sunda Shelf (Sumatra to Borneo) and eastward into China and Japan. And at least some species use ultrasonic sound to communicate through the noise of running water. Now, Yang et al. (2011) find that they may produce the greatest known variety of anti-bacterial substances known, and that they hold promise for becoming new weapons in the battle against antibiotic-resistant infections. The dorous frogs have been described as smelling like decomposing flesh. Zhang's research group at the Kunming Institute of Zoology, of the Chinese Academy worked to identify the specific antimicrobial peptides (AMPs) for developing new antibiotics. They identified more than 700 of these substances from nine species of odorous frogs and concluded that the AMPs account for almost one-third of all AMPs found in the world, the greatest known diversity of these germ-killing chemicals. Interestingly, some of the AMPs have a dual action, killing bacteria directly and simultaneouly activating the immune system. Their results sugest that identical AMPs were widely distributed in odorous frogs; 49 known AMPs can be found in different amphibian species. Purified peptides showed a strong and effective antimicrobial activity against four tested strains of microbe. They synthesized another 23 peptides and evaluated their antimicrobial, antioxidant, hemolytic, immunomodulatory and insulin-releasing properties. Their research demonstrates the extreme diversity of AMPs in amphibian skins and provides numerous templates for developing novel peptide antibiotics. Thus, we have yet another reason to protect biodiversity.

Xinwang Yang, Wen-Hui Lee, Yun Zhang. 2011. Extremely Abundant Antimicrobial Peptides Existed in the Skins of Nine Kinds of Chinese Odorous Frogs. Journal of Proteome Research, 2011: 111118134814004 DOI: 10.1021/pr200782u

Thursday, July 21, 2011

Oldest Viviparous Squamata

The embryonic skeletons can be seen in 
side of their mother's remains. Photo
Credit: Susan Evans.

The lizard genus Yabeinosaurus Endo and Shikama 1942 was first described from Early Cretaceous deposits from the Jehol Group of northeastern China. Early interpretations suggested, Yabeinosaurus  was a small, weakly ossified lizard with gekkotan affinities. However, Evans et al. (2005) reported adults exceeded  300 mm snout–pelvis length, and lizard had a large, heavily ossified and strongly sculptured skull. Their results suggested Yabeinosaurus was close to the iguanian–scleroglossan dichotomy and they hypothesized that Yabeinosaurus may represent a relict species in the Jehol Biota, a survivor of the Pan-Laurasian lizard fauna of the Jurassic. Now, Wang and Evans (2011) document viviparity in Yabeinosaurus with the remains of a gravid female that contains more than 15 young with skeletal development that suggests they are near full term. Because Yabeinosaurus occupies a relatively basal position within crown-group squamates, they suggests that the anatomical and physiological preconditions for viviparity arose early within Squamata. It is the oldest terrestrial reptile known to give live birth, and it extends the evolution of viviparity to at least 120 million years ago. Yabeinosaurus probably lived on the banks of a stream and the remains were associated with hundreds of exquisitely preserved specimens of dinosaurs, fish, amphibians, reptiles, birds and mammals, plants and invertebrates.

Evans, S. E.; Wang, Y.; Li C. (2005). "The Early Cretaceous lizard genus Yabeinosaurus from China: resolving an enigma". Journal of Systematic Palaeontology 3 (4): 319–335. doi:10.1017/S1477201905001641.

Yuan Wang and Susan E. Evans. 2011. A gravid lizard from the Cretaceous of China and the early history of squamate viviparity. Naturwissenschaften

Wednesday, July 20, 2011

Molecules From the Skin of Hyla simplex

The skin of tree frogs tells a story of peril. Constantly assaulted by predators, these amphibians survive by waging chemical warfare using skin secretions. The potent molecules within may help humans too, as a potential source of new medications. Researchers have now analyzed the skin secretions of Chinese tree frogs, Hyla simplex, and found a potent mix of deadly snake-venom-like toxins as well as therapeutic chemicals (J. Proteome Res., DOI: 10.1021/pr200393t).

Han Liu of the Kunming Institute of Zoology at the Chinese Academy of Sciences, and colleagues captured and collected secretions of tree frogs from forests in Guangxi province. They determined the amino acid sequences of 27 proteins and peptides using a standard sequencing method coupled with mass spectrometry. The researchers also confirmed the protein and peptide identities using DNA sequences derived from RNA samples in the skin secretions.

The researchers subjected the agents to a battery of tests to check whether they could act as antimicrobials, painkillers, neurotoxins, or promoters of blood vessel regrowth. These studies revealed that some skin secretions are toxic to mice, water snakes, insects, and birds. Others seemed capable of helping the frog heal its own wounded flesh or dull its perception of pain.

The researchers also found that the amino acid sequences of several of the proteins bear remarkable similarity to those of neurotoxins from snake venom. Because snakes are predators of tree frogs, Liu says that the similarity in their toxins may indicate an arms race in which each species evolves increasingly sophisticated chemical weaponry and resistance. Though more work is needed to confirm this relationship, Liu says, frog skin could shed light on how a small amphibian survives in a snaky wilderness.

The above is a press release from the Kunming Institute of Zoology at the Chinese Academy of Sciences.

Saturday, May 21, 2011

Xilousuchus sapingensis - An Early Archosaur

A reconstruction of X. sapingensis, based on the fossil. Sterling Nesbitt
A fossil unearthed in China in the 1970s of a creature that died about 247 million years ago, originally thought to be a distant relative of both birds and crocodiles, turns out to have come from the crocodile family tree after it had already split from the bird family tree, according to research led by a University of Washington paleontologist.

The only known specimen of Xilousuchus sapingensis has been reexamined and is now classified as an archosaur. Archosaurs, characterized by skulls with long, narrow snouts and teeth set in sockets, include dinosaurs as well as crocodiles and birds.

The new examination dates the X. sapingensis specimen to the early Triassic period, 247 million to 252 million years ago, said Sterling Nesbitt, a UW postdoctoral researcher in biology. That means the creature lived just a short geological time after the largest mass extinction in Earth’s history, 252 million years ago at the end of the Permian period, when as much as 95 percent of marine life and 70 percent of land creatures perished. The evidence, he said, places X. sapingensis on the crocodile side of the archosaur family tree.

“Archosaurs might have survived the extinction or they might have been a product of the recovery from the extinction,” Nesbitt said.

The research is published May 17 online in Earth and Environmental Science Transactions of the Royal Society of Edinburgh, a journal of Cambridge University in the United Kingdom.

Co-authors are Jun Liu of the American Museum of Natural History in New York and Chun Li of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China. Nesbitt did most of his work on the project while a postdoctoral researcher at the University of Texas at Austin.

The X. sapingensis specimen – a skull and 10 vertebrae – was found in the Heshanggou Formation in northern China, an area with deposits that date from the early and mid-Triassic period, from 252 million to 230 million years ago, and further back, before the mass extinction.

The fossil was originally classified as an archosauriform, a “cousin” of archosaurs, rather than a true archosaur, but that was before the discovery of more complete early archosaur specimens from other parts of the Triassic period. The researchers examined bones from the specimen in detail, comparing them to those from the closest relatives of archosaurs, and discovered that X. sapingensis differed from virtually every archosauriform.

Among their findings was that bones at the tip of the jaw that bear the teeth likely were not downturned as much as originally thought when the specimen was first described in the 1980s. They also found that neural spines of the neck formed the forward part of a sail similar to that found on another ancient archosaur called Arizonasaurus, a very close relative of Xilousuchus found in Arizona.

The family trees of birds and crocodiles meet somewhere in the early Triassic and archosauriforms are the closest cousin to those archosaurs, Nesbitt said. But the new research places X. sapingensis firmly within the archosaur family tree, providing evidence that the early members of the crocodile and bird family trees evolved earlier than previously thought.

“This animal is closer to a crocodile, but it’s not a crocodile. If you saw it today you wouldn’t think it was a crocodile, especially not with a sail on its back,” he said.

The research was funded by the National Science Foundation, the Society of Vertebrate Paleontology, the American Museum of Natural History and the Chinese Academy of Sciences.

“We’re marching closer and closer to the Permian-Triassic boundary with the origin of archosaurs,” Nesbitt said. “And today the archosaurs are still the dominant land vertebrate, when you look at the diversity of birds.”

Monday, April 4, 2011

Zhuchengtyrannus magnus - a T. rex Relative

Scientists have identified a new species of gigantic theropod dinosaur, a close relative of T. rex, from fossil skull and jaw bones discovered in China.

According to findings published in the scientific journal Cretaceous Research, the newly named dinosaur species “Zhuchengtyrannus magnus” probably measured about 11 metres long, stood about 4 metres tall, and weighed close to 6 tonnes.

“We named the new genus Zhuchengtyrannus magnus - which means the ‘Tyrant from Zhucheng’ - because the bones were found in the city of Zhucheng, in eastern China's Shandong Province,” says Dr Hone.

A key member of the international team of scientists involved in the study is Professor Xu Xing of the Beijing Institute of Vertebrate Paleontology and Paleoanthropology in China.

Professor Xu has named more than 30 dinosaurs, making him the world leader in describing new dinosaur species.

The tyrannosaurines, the group including T. rex and its closest relatives, were huge carnivores characterised by small arms, two-fingered hands, and large powerful jaws that could have delivered a powerful bone-crushing bite. They were likely both predators and scavengers.

Together with nearby sites, the quarry in Shandong Province, eastern China where the remains of this huge carnivore were found contains one of the largest concentrations of dinosaur bones in the world. Most of the specimens recovered from the quarry belong to a gigantic species of hadrosaur, or duck-billed dinosaur. Research suggests that the area contains so many dinosaur fossils because it was a large flood plain where many dinosaur bodies were washed together during floods and fossilised.

Zhuchengtyrannus magnus was named in honour of Zhucheng, the city in eastern China where the fossils were found. Tyrannus is the Latin for ‘king’ or ‘tyrant’, and magnus is the Latin for ‘great’. The name is intended to convey ‘great tyrant of Zhucheng’. This new dinosaur species, alongside Tarbosaurus and Tyrannosaurus, is one of the largest members of the tyrannosaurines, a specialised group of large theropods that lived during the Late Cretaceous Period (99 to 65 million years ago).

David W.E. Hone, Kebai Wang, Corwin Sullivan, Xijin Zhao, Shuqing Chen, Dunjin Li, Shuan Ji, Qiang Ji, Xing Xu. A new tyrannosaurine theropod, Zhuchengtyrannus magnus is named based on a maxilla and dentary. Cretaceous Research, 2011; DOI: 10.1016/j.cretres.2011.03.005

Tuesday, January 25, 2011

A New Species of Wolf Snake from Yunnan China

There are more than 40 species of  Asian Wolf Snakes in the genus Lycodon. Gernot Vogel and Patrick David have now described Lycodon synaptor from Yunnan Province in China. The new species can be recognized by the combination of the loreal scale not entering orbit; and its narrow dorsal bands, with the first band starting at ventral 5–9. Most other characters are shared with Lycodon fasciatus. The species is indirectly named in honor of Dr. Wolfgang B√∂hme for his efforts to unite professional and amateur herpetologists. There is no information available on the biology of Boehme’s Wolf Snake, but the region it comes from - Dongchuan - is mountainous.

Vogel, G. and P. David. 2010. A new species of the genus Lycodon ) Boie, 1826) from Yunnan Province China (Serpentes: Colubridae). Bonn Zoological Bulletin 57:289-296.