Advances in studies on hepatic stem cells

The question whether hepatic stem cells exist or not has been debated for several decades. Current researches confirm that there are hepatic stem cells in the liver. Oval cells, putative bipotential hepatic stem cells, are probably located within canals of Hering, portal tracts or branches of biliary trees. Bone marrow is a potential source of oval cells, indicating that there exists a close relationship between liver and hematopoiesis in adulthood. Hepatic stem cells are able to proliferate in vitro and can be induced to differentiate into hepatocytes. This will provide a promising approach of cell transplantation, tissue engineering and gene therapy for liver diseases. In this review, the evidence of their presence, origin, identification, proliferation in vitro, differentiation by induction, application prospects of hepatic stem cells and future directions for the field are discussed.     

Stamen specification and anther development in rice

Male reproductive development is a complex biological process which includes the formation of the stamen with differentiated anther tissues, in which microspores/pollens are generated, then anther dehiscence and subsequently pollination. Stamen specification and anther development involve a number of extraordinary events such as meristem transition, cell division and differentiation, cell to cell communication, etc., which need the cooperative interaction of sporophytic and gametophytic genes. The advent of various tools for rice functional gene identification, such as complete genome sequence, genome-wide microarrays, collections of mutants, has greatly facilitated our understanding of mechanisms of rice stamen specification and anther development. Male sterile lines are critical for hybrid rice breeding, therefore understanding these processes will not only contribute greatly to the basic knowledge of crop developmental biology, but also to the development of new varieties for hybrid rice breeding in the future.     

Induced pluripotent stem cell (iPS) technology: promises and challenges

In 2006, an article published in Cell by Shinya Yamanaka took by surprise the stem cell research community. By performing systematic retroviral transduction of factors enriched in embryonic stem (ES) cells, the authors demonstrated the reprogramming of mouse fibroblasts into an ES cell-like state. These cells, baptized iPS (induced pluripotent stem) cells, were immediately recognized as a ground-breaking discovery. Subsequently, the same authors and other groups reported a similar achievement with human fibroblasts. Two years later, the number of top quality papers on iPS is astonishing, and interest in the scientific community has risen to a fever pitch. But although iPS has the potential to revolutionize Regenerative Medicine, important questions still remain unanswered. Work from multiple laboratories worldwide including ours is focused on deciphering the molecular mechanisms of iPS, and trying to improve the technique to make it suitable for the clinic. In this review article we briefly discuss the past, present and future of iPS, with emphasis on urgent issues to be solved. Supported by the National Nature Science Foundation of China (Grant Nos. 30725012, 30630039 and 90813033), Knowledge Innovation Project of Chinese Academy of Sciences (Grant No. KSCX2-YW-R-48), National Key Basic Research and Development Program of China (Grant Nos. 2006CB701504, 2006CB943600, 2007CB948002, 2007CB947804. 2007CB947900) and Guangzhou Science and Technology Development Funds (Grant No. 2008A1-E4011)     

The mobilization of rat’s mesenchymal stem cells into peripheral blood by LiCL and its potency differentiation

Mesenchymal stem cells （MSCs） are multipotent cells, which can differentiate into different tissues. It is still controversial whether MSCs can be isolated from adult peripheral blood （PB） under normal conditions and whether they can be mobilized in a way similar to that of hematopoieUc stem cells （HSCs）. In this study, rat MSCs circulating in the PB under normal conditions can be isolated and cultured, and MSCs from PB and BM can be mobilized by LiCL. The mobilized MSCs can be induced to differentiate into neuron by such factors as β-mercaptoethanol and supernatants of nerve cell cultures. The present study provides a broader perspective on the repair of neural trauma.     

Process modeling of fuel cell vehicle power system

Constructed here is a mathematic model of PEM Fuel Cell Vehicle Power System which is composed of fuel supply model, fuel cell stack model and water-heat management model. The model was developed by Matlab/Simulink to evaluate how the major operating variables affect the output performances. It shows that the constructed model can represent characteristics of the power system closely by comparing modeling results with experimental data, and it can be used in the study and design of fuel cell vehicle power system. Supported by the National High Technology Research and Development Program of China (Grant No. 2007AA05Z145), State Key Development Program for Basic Research of China (Grant No. 2007cb209707) and Shanghai Science and Technology Project (Grant Nos. 06SN07115 and 07JC14024)     

Genome-wide distribution of histone H3 acetylation in all- trans retinoic acid induced neuronal differentiation of SH-SY5Y cells

With chromatin immunoprecipitation (ChIP) and promoter DNA microarray analyses (ChIP-on-chip), we analyzed the variations of acetylation on histone H3 in all-trans retinoic acid (RA) induced neuronal cell differentiation. Neuroblastoma SH-SY5Y cells were treated with RA for 24 h and the acetylation on histone H3 in the promoter region of the genes was detected. Results showed that, after treatment, the level of acetylation on histone H3 elevated in 597 genes in the genome, and reduced in the other 647 genes compared with those of the control. In summary, we have successfully adopted a high throughput technique to detect and analyze variations of acetylation of histone H3 in human genome at the early phage of RA induced neuronal differentiation of the SH-SY5Y cells. Supported by National Natural Science Foundation of China (Grant Nos. 90408007 and 30721063) and National Key Basic Research and Development Program of China (Grant No. 2004CB518605)     

Arbitrarily long distance quantum communication using inspection and power insertion

The biggest obstacle for long distance quantum communication is the channel loss and the channel noise on photons. In this paper, a method to solve this problem was analyzed using inspection and power insertion (IPI). It is proved that quantum communication may be established over arbitrarily long distance using this technology. The amount of resources required is a polynomial function of the distance. IPI is proposed as a general technique to prolong quantum secure direct communication where secret messages are transmitted directly over a quantum channel. Supported by the National Basic Research Program of China (Grant No. 2006CB921106), National Natural Science Foundation of China (Grant No. 10325521) and Key Project of Ministry of Education of China (Grant No. 306020)     

Study on the specific interaction between angiogenin and aptamer by atomic force microscopy （AFM）

The specific interaction between angiogenin and aptamer has been investigated by using AFM. The specificity of the interaction is revealed by comparing the binding probability of aptamer to other elements in a series of control experiments. The results have shown that there is specific interaction force between angiogenin and aptamer. Moreover, the single molecular pull-off force between angiogenin and aptamer has also been determined using the Poisson statistical method to be 133.7±11.7 pN. These findings obtained are helpful to the better revelation of recognition mechanism between angiogenin and aptamer, which provided basis for further understanding the inhibition of the aptamer to angiogenic activity.     

Induction of corneal epithelial prosenitors from bone-marrow mesenchymal stem cells of rhesus monkeys in vitro

Bioengineered corneas are substitutes for human donor tissue that are designed to treat severe disease affecting ocular surfaces. However, a shortage of candidate seed cells for bioengineering corneas is still a problem. Bone-marrow mesenchymal stem cells （MSCs） are capable of multilineage differentiation. Therefore, we determined whether MSCs differentiate into corneal epithelial cells （ECs）. We applied three exoteric-microenvironmental systems to induce MSCs to become ECs. Induced MSC were identified by means of morphologic examination, immunocytochemical analysis, and flow cytometry. MSCs grown in one microenvironment had characteristics similar to those of corneal epithelial progenitors. Induced MSCs expressed markers for EC, including integrin 61, Cx43, Pax6, and P63. MSCs were successfully induced to become corneal epithelial progenitors. Therefore, the use of MSCs may hold substantial promise for reconstructing the ocular surface after corneal injury.[第一段]     

Cell fusion is the principal source of bone-marrow-derived hepatocytes

Evidence suggests that haematopoietic stem cells might have unexpected developmental plasticity, highlighting therapeutic potential. For example, bone-marrow-derived hepatocytes can repopulate the liver of mice with fumarylacetoacetate hydrolase deficiency and correct their liver disease. To determine the underlying mechanism in this murine model, we performed serial transplantation of bone-marrow-derived hepatocytes. Here we show by Southern blot analysis that the repopulating hepatocytes in the liver were heterozygous for alleles unique to the donor marrow, in contrast to the original homozygous donor cells. Furthermore, cytogenetic analysis of hepatocytes transplanted from female donor mice into male recipients demonstrated 80,XXXY (diploid to diploid fusion) and 120,XXXXYY (diploid to tetraploid fusion) karyotypes, indicative of fusion between donor and host cells. We conclude that hepatocytes derived form bone marrow arise from cell fusion and not by differentiation of haematopoietic stem cells.     

Records of volcanic events since AD 1800 in the East Rongbuk ice core from Mt. Qomolangma

Continuous Bi profile of the East Rongbuk (ER) ice core near Mt. Qomolangma reveals nine major volcanic events since AD 1800. Compared with Volcanic Explosivity Index (VEI), it shows that the concentrations of Bi in the ER ice core can reflect the major volcanic events within the key areas. This provides a good horizon layer for ice core dating, as well as a basis for reconstructing a long sequence of volcanic records from the Qinghai-Xizang (Tibet) Plateau ice cores. Supported jointly by National Basic Research Program of China (Grant No. 2007CB411501), National Natural Science Foundation of China (Grant No. 90411003), Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX3-SW-344) and Hundred Talents Project of the Chinese Academy of Sciences     

Biomimetic coupling effect of non-smooth mechanical property and microstructural features on thermal fatigue behavior of medium carbon steel

Some kinds of particular functions possessed by natural organisms are often formed by coupling up the multiple typical features on their body surfaces. Inspired by the coupling phenomenon in biological system, the medium carbon steel specimens with the coupling effect of non-smooth mechanical property and microstructural features were fabricated by laser processing. Thermal fatigue behavior of specimens with biomimetic coupling surface was investigated and compared. The results confirmed that such a biomimetic method has the beneficial effect on improving the thermal fatigue property of medium carbon steel specimens. The related mechanisms behind the biomimetic coupling effect for explaining the enhanced thermal fatigue resistance were discussed preliminarily. Supported by the Key Program of National Natural Science Foundation of China (Grant No. 50635030), Project 985-Automotive Engineering of Jilin University, International Cooperation key Project (Grant No. 2005DFA00850) and Transfer Foundation of Scientific and Technical Fruits in Agriculture (Grant No. 2007GB23600467) of Ministry of Science and Technology of China     

Arctic dipole anomaly and summer rainfall in Northeast China

A dipole structure anomaly in summer Arctic atmospheric variability is identified in this study, which is characterized by the second mode of empirical orthogonal function （EOF） analysis of summer monthly mean sea level pressure （SLP） north of 70°N, accounting for 12.94% of the variance. The dipole anomaly shows a quasi-barotropic structure with opposite anomalous centers over the Canadian Arctic and the Beaufort Sea and between the Kara Sea and the Laptev Sea. The dipole anomaly reflects alternating variations in location of the polar vortex between the western and eastern Arctic regions. The positive phase of the dipole anomaly corresponds to the center of the polar vortex over the western Arctic, leading to an increase in summer mean rainfall in Northeast China. The dipole anomaly has a predominant 6-year periodicity, and shows interdecadal variations in recent decades.     

Ionic liquids based on S-alkylthiolanium cations and TFSI anion as potential electrolytes

New ionic liquids based on S-alkylthiolanium cations with TFSI anions were synthesized and charac-terized.The physical and electrochemical properties,including melting point,thermal stability,solubility,viscosity,conductivity and electrochemical window,were reported.Relation between these properties and the structure of the cations was discussed.In this series,T4TFSI and T5TFSI have melting points below -60℃,and their conductivities are 2.10 mS/cm and 1.46 mS/cm;their electrochemical windows are 4.1 V and 4...     

Near-infrared spectroscopy-based quantification of substrate and aqueous products in wastewater anaerobic fermentation processes

In this study, a Fourier transform near-infrared （FT-NIR） technique was used for process monitoring of anaerobic fermentation. Orthogonal signal correction （OSC） method was used as NIR spectral pre- processing options. Calibration models were established and the validation of the method was per- formed with the sucrose, ethanol and volatile fatty acids （VFAs） contents determined by the anthrone and gas chromatography methods, respectively. Spectral range and the number of internal latent variables were optimized for the best correlation coefficient. Test set validation of sucrose resulted in excellent measurement of prediction performance and the correlation coefficient of determination is 0.930. Similar prediction statistics for individual VFA and total VFA contents were obtained. These re- sults proved that the NIR spectroscopy technology is able to quantify the contents of both volatile fatty acids and sucrose in wastewater anaerobic fermentation process.     

Elemental composition in surface snow from the ultra-high elevation area of Mt. Qomolangma （Everest）

A total of 14 surface snow （0-10 cm） samples were collected along the climbing route （6500-8844 m a.s.h） on the northern slope of Mt. Qomolangma in May, 2005. Analysis of elemental concentrations in these samples showed that there are no clear trends for element variations with elevation due to redistribution of surface snow by strong winds during spring. In addition, local crustal aerosol inputs also have an influence on elemental composition of surface snow. Comparison between elemental concentration datasets of 2005 and 1997 indicated that data from 2005 were of higher quality. Elemental concentrations （especially for heavy metals） at Mt. Qomolangma are comparable with polar sites, and far lower than large cities. This indicates that anthropogenic activities and heavy metal pollution have little effect on the Mt. Qomolangma atmospheric environment, which can be representative of the background atmospheric environment.     

Optical limiting of niobic tellurite glass induced by self-trapped exciton absorption of the AgCl nanocrystal dopant

Niobic tellurite glass doped by silver chloride nanocrystal was prepared with the melting-quenching and heat treatment method, and the self-trapped exciton absorption band of the silver chloride nanocrystal was observed at 532 nm in the UV-visible absorption spectrum. The glass structure characteristics were investigated by Raman spectroscopy, and the mechanism of self-trapped exciton was analyzed by Jahn-Teller model. Its optical limiting was measured with 532 nm picosecond laser pulses, and the corresponding nonlinear absorption coefficient was measured with open-aperture Z-scan. The experimental results showed that optical limiting at 532 nm was attributed to free carrier absorption between the self-trapped state and the continuum band. Supported by Shanghai Leading Academic Discipline Project (Grant No. B408), National Basic Research Program of China (Grant Nos. 2006CB806006, 2006CB921105), Program for Changjiang Scholars and Innovative Research Team in University, Doctoral Program of High Education (Grant No. 20050269011) and Project sponsored by Shanghai Science and Technology Committee (Grant Nos. 06DJ14008, 07dz22025, 06QH14003)