No. 76

June 2011

Headline News Innovation and Development

Applied Technology

Basic Science Cooperation between CAS and Local Authorities
Bioscience International Cooperation Brief News Geoscience


Conversional Liver Cells Obtained

The Chinese people account for about one-third of 350 million chronic hepatitis B virus carriers in the world. Hepatitis B virus-induced chronic liver disease has become the second main cause of infectious disease - associated death in China. A research team led by Prof. Hui Lijian from the Shanghai Institutes for Biological Sciences, CAS published online the successful conversion of mouse tail cells into functional liver cells on Nature on 12th, May. For the first time, the team demonstrated that somatic non-liver cells could be converted directly into functional liver cells. This finding might lead to generate functional liver cell for liver transplantation from patients¡¯ own somatic cell. The discovery was firstly reported in the world. Their results demonstrated not only that induced hepatic cells (iHep) look like primary hepatocytes in epithelial morphology and in gene expression profiles, but also their function in vivo closely mirrors their natural counterpart, such as sugar storage, lipid intake, and hormone and drug metabolism. Further animal experiments were carried together with Prof. Wang Xin¡¯s team from the same institute. Nature and other internationally renowned scientific journals and institutes commented that this finding is a breakthrough that sets a standard for other following research in the field.

Anti-tumor Biosynthesis: Research on Natural Products

With three years or more hard work, researchers of the State Key Lab of the Bio-organic Chemistry, Shanghai Institute of Organic Chemistry, CAS, adopted the PCR approach of cloning the specific genes of hydroxy-methylglutaryl coenzyme A synthetase and cloned the whole FR901464 biosynthetic gene cluster from pseudomonas sp. No. 2663. This gene cluster contains 20 genes that were encoded as five AT-less polyketide synthases (PKS), one hybrid polyketide synthase/ nonribosomal polypeptide synthase (NRPS), one nonribosomal polypeptide synthase (NRPS), three independent acyltransferases (AT), four polyketide skeleton ¦Â-alkylation associated proteins, four post-modifying enzymes and two regulating proteins. Through the combination of in vivo gene knockout and in vitro biochemical experiments, researchers initially explained FR901464¡¯s unique biosynthetic way: adopt the highly heterozygous ternary system of PKS-NRPS-HCS with glycerin as the starting unit of PKS to conduct Baeyer-Villiger oxide dissociation of polyketone chains. This research revealed the complicated and diverse biosynthetic mechanisms in the biosynthesis of natural polyketone products and created conditions for further discovery of new enzyme-catalyzed reactions and the production of substance with similar structures through the regulation of its biosynthetic genes. Some results of this research were published on J. Am. Chem. Soc. 2011, 133, 2452-2462.

A Giant Cousin of Tyrannosaurus Rex Found in China

Drs. David Horn, Corwin Sullivan, Profs. Xu Xing and Zhao Xijing at the Institute of Vertebrate Paleontology and Paleoanthropology, CAS, collaborated with researchers at the Zhucheng Dinosaur Museum and the Chinese Academy of Geological Sciences, have identified a new species of gigantic theropod dinosaur, a close relative of T. rex, from teeth and maxilla discovered from the upper Cretaceous Wangshi Formation of Zhucheng, Shangdong Province, China. According to findings published recently on the journal of Cretaceous Research, the newly named dinosaur species ¡°Zhuchengtyrannus magnus¡± is inferred to be about 11 meters long, stood about 4 meters high, and weighed close to 6 tons. Comparable in size and scale to the legendary Tyrannosaurus. rex, this new dinosaur is one of the largest theropod (carnivorous) dinosaurs ever identified by scientists. Itcan be distinguished from other tyrannosaurines by a combination of unique features in the skull not seen in any other theropod. The tyrannosaurines existed in North America and eastern Asia during the Late Cretaceous Period, which lasted from about 99 to 65 million years ago. T. rex is the most famouse dinosaur among the tyrannosaruines.

New Solution for Algal Blooms

The eutrophication frequently occurs and the algal blooms increasingly develop in some lakes and reservoirs. Once microcystis are released to water in algal blooms, it is harmful and difficult to remove using the conventional treatments. The Microcystis may threaten aquatic species and human health. Dr. Fang Yanfen, who was a graduate of the Institute of Mountain Hazards and Environment, CAS, with guidance from Prof. Cheng Genwei of the same Institute, had provided a new efficient method to eliminate one of the most commonly found cyanotoxin in water, microcystin-LR (MC-LR), using a relatively new semiconductor material, bismuth oxybromide (BiOBr) as photocatalyst. Microcystins are cyclic peptides that are acute toxic to animals and human, acting mainly through interactions with protein phosphatase PP1 and PP2A. Exposure to high levels of these environmentally persistent microcystins can lead to liver damage and even result in death. Also, chronic exposure to low levels of microcystins has been suspected to lead to cancer. The normal water treatments measures are not able to completely remove MC-LR in the drinking water. But the synthesis and characteristics of BiOBr, as a new type catalyst, have been previously studied, which showed good catalytic activity under visible light. The BiOBr to photodegrade MC-LR was used for the first time in their test, and they found BiOBr could selectively decarboxylate the stable free carboxyl groups that were previously found difficult to degrade by other methods. Since these key functional groups are effectively eliminated, it could mean that the toxicity can be reduced even if the macrostructure of MC-LR is not completely destroyed. They are currently working on further elucidating the detailed degradation pathways of this method and also validating its practical feasibility in drinking water treatment. Their paper entitled Unique Ability of BiOBr to Decarboxylate D-Glu and D-MeAsp in the Photocatalytic Degradation of Microcystin-LR in Water has been selected as Top Paper of 2010 in the environmental technology field by the Environmental Science & Technology (Yanfen, F.; Yingping, H.; Jing, Y.; Pan, W.; Genwei, C. 2011, 45 (4), 1593_1600) of the US Chemical Society.

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