Wnt-beta-catenin signaling initiates taste papilla development

Fungiform taste papillae form a regular array on the dorsal tongue. Taste buds arise from papilla epithelium and, unusually for epithelial derivatives, synapse with neurons, release neurotransmitters and generate receptor and action potentials. Despite the importance of taste as one of our five senses, genetic analyses of taste papilla and bud development are lacking. We demonstrate that Wnt-beta-catenin signaling is activated in developing fungiform placodes and taste bud cells. A dominant stabilizing mutation of epithelial beta-catenin causes massive overproduction of enlarged fungiform papillae and taste buds. Likewise, genetic deletion of epithelial beta-catenin or inhibition of Wnt-beta-catenin signaling by ectopic dickkopf1 (Dkk1) blocks initiation of fungiform papilla morphogenesis. Ectopic papillae are innervated in the stabilizing beta-catenin mutant, whereas ectopic Dkk1 causes absence of lingual epithelial innervation. Thus, Wnt-beta-catenin signaling is critical for fungiform papilla and taste bud development. Altered regulation of this pathway may underlie evolutionary changes in taste papilla patterning.     

不同林地清理方式下生物炭和氮添加对桉树红锥混交林土壤养分的影响

【目的】阐明不同林地清理方式下(火烧清理和人工清理)生物炭和氮添加对桉树红锥混交林土壤养分的影响,为人工林的经营管理提供参考。【方法】在火烧清理和人工清理林地的桉树红锥混交林中,设置生物炭和氮添加的控制实验,研究生物炭和氮添加对土壤有机碳(SOC)、全氮(TN)、全磷(TP)、全钾(TK)、有效磷(AP)和有效钾(AK)含量的影响。【结果】不同林地清理方式下,生物炭和氮添加对林地土壤养分的影响存在差异:与对照相比,人工清理林地时,添加生物炭显著增加了20～40cm土层的AP含量;氮添加极显著增加了0～10cm土层的SOC、TP、AP含量和C∶N;10～20cm土层的SOC、AK含量,20～40cm土层的AP和AK含量也显著增加;而0～10cm土层的N∶P则极显著降低。林地清理方式为火烧清理时,生物炭添加极显著增加0～10cm土层的TP含量,而0～10cm、10～20cm土层的SOC和AK含量,0～10cm土层的C∶N,10～20cm的AP∶TP、C∶P以及0～10cm、10～20cm、20～40cm土层的AK∶TK显著降低,0～10cm土层的AP含量、AP∶TP、C∶P和N∶P更是极显著降低。氮添加显著降低10～20cm土层的N∶P以及0～10cm土层的AP∶TP,0～10cm土层的AP含量以及10～20cm的TN含量下降达到极显著水平。【结论】人工清理林地条件下,实施生物炭和氮添加有利于提高桉树红锥混交林的土壤养分。     

Synthesis of the 3D porous carbon-manganese oxide (3D-C@MnO) nanocomposite and its supercapacitor behavior study

A 3D porous carbon-manganese oxide ([email protected]) nanocomposite is successfully synthesized via a thermal plasma deposition method. The chemical bonds and compositions, phase structures, surface morphologies, etc. of as-obtained [email protected] nanocomposite were characterized by the various equipment, such as X-ray diffractometer, X-ray photoelectron spectroscopy, and electron microscopes. The electrochemical performances of the [email protected] nanocomposite electrode showed a specific capacitance of 780 F g^?1 at a current density of 2 A g^?1 and a capacitance retention rate of 99% after 5000 charge-discharge cycles at a high current density of 10 A g^?1. These excellent capacitive performances may be attributed to the encapsulation of MnO nanoparticles by porous carbon sheets in the [email protected] MnO nanocomposite structure. It is believed that the carbon-encapsulated MnO nanoparticles can be protected from a volume deformation during the charge adsorption/desorption cycle and can be electrically improved by the encapsulated carbon sheets, resulting in better overall capacitive performance. In addition, this study also demonstrates the practical applicability by assembling a supercapacitor using the as-obtained [email protected] nanocomposite to glow a light emitting diode.     

PTC124 targets genetic disorders caused by nonsense mutations

Nonsense mutations promote premature translational termination and cause anywhere from 5-70% of the individual cases of most inherited diseases. Studies on nonsense-mediated cystic fibrosis have indicated that boosting specific protein synthesis from <1% to as little as 5% of normal levels may greatly reduce the severity or eliminate the principal manifestations of disease. To address the need for a drug capable of suppressing premature termination, we identified PTC124-a new chemical entity that selectively induces ribosomal readthrough of premature but not normal termination codons. PTC124 activity, optimized using nonsense-containing reporters, promoted dystrophin production in primary muscle cells from humans and mdx mice expressing dystrophin nonsense alleles, and rescued striated muscle function in mdx mice within 2-8 weeks of drug exposure. PTC124 was well tolerated in animals at plasma exposures substantially in excess of those required for nonsense suppression. The selectivity of PTC124 for premature termination codons, its well characterized activity profile, oral bioavailability and pharmacological properties indicate that this drug may have broad clinical potential for the treatment of a large group of genetic disorders with limited or no therapeutic options.     

一种围数为八的低密度校验码校验矩阵设计

提出了一种低密度校验（IDPC）码的规则校验矩阵设计算法．首先设计3个不同的子矩阵,每个子矩阵通过对单位矩阵进行不同的移位运算后组合生成,然后将这3个子矩阵组合生成所需要的低密度校验矩阵,最后利用文中提到的短环检验算法搜索出使得生成的校验矩阵四环数、六环数均为零的移位算子．用该校验矩阵所对应的生成矩阵对随机信息进行编码,AWGN信道下的仿真结果表明,具有逼近MacKay随机码的误码率性能．     

Provable Efficient Certificateless Group Key Exchange Protocol

Certificateless public key cryptography （CL-PKC） avoids the inherent escrow of identity-based cryptography and does not require certificates to guarantee the authenticity of public keys. Based on CL-PKC, we present an efficient constant-round group key exchange protocol, which is provably secure under the intractability of computation Diffie-Hellman problem. Our protocol is a contributory key exchange with perfect forward secrecy and has only two communication rounds. So it is more efficient than other protocols. Moreover, our protocol provides a method to design efficient constant-round group key exchange protocols and most secret sharing schemes could be adopted to construct our protocol.     

The recent expansion of Pluto's atmosphere

Stellar occultations--the passing of a relatively nearby body in front of a background star--can be used to probe the atmosphere of the closer body with a spatial resolution of a few kilometres (ref. 1). Such observations can yield the scale height, temperature profile, and other information about the structure of the occulting atmosphere. Occultation data acquired for Pluto's atmosphere in 1988 revealed a nearly isothermal atmosphere above a radius of approximately 1,215 km. Below this level, the data could be interpreted as indicating either an extinction layer or the onset of a large thermal gradient, calling into question the fundamental structure of this atmosphere. Another question is to what extent Pluto's atmosphere might be collapsing as it recedes from the Sun (passing perihelion in 1989 in its 248-year orbital period), owing to the extreme sensitivity of the equilibrium surface pressure to the surface temperature. Here we report observations at a variety of visible and infrared wavelengths of an occultation of a star by Pluto in August 2002. These data reveal evidence for extinction in Pluto's atmosphere and show that it has indeed changed, having expanded rather than collapsed, since 1988.     

Fgf8 is required for outgrowth and patterning of the limbs

The expression pattern and activity of fibroblast growth factor-8 (FGF8) in experimental assays indicate that it has important roles in limb development, but early embryonic lethality resulting from mutation of Fgf8 in the germ line of mice has prevented direct assessment of these roles. Here we report that conditional disruption of Fgf8 in the forelimb of developing mice bypasses embryonic lethality and reveals a requirement for Fgf8 in the formation of the stylopod, anterior zeugopod and autopod. Lack of Fgf8 in the apical ectodermal ridge (AER) alters expression of other Fgf genes, Shh and Bmp2.     

城市二级排水回用作循环冷却水处理技术

城市二级排水回用作循环冷却水 ,重点是应去除二级排水中的COD和氨氮 ,本文介绍了相关的净化技术 ,并对其进行了评价     

Statistical tests on two characteristics of the shapes of cluster diagrams

A cluster diagram is a rooted planar tree that depicts the hierarchical agglomeration of objects into groups of increasing size. On the null hypothesis that at each stage of the clustering procedure all possible joins are equally probable, we derive the probability distributions for two properties of these diagrams: (1)S, the number of single objects previously ungrouped that are joined in the final stages of clustering, and (2)m _k, the number of groups ofk+1 objects that are formed during the process. Ecological applications of statistical tests for these properties are described and illustrated with data from weed communities of Saskatchewan fields.This work was supported by the Natural Sciences and Engineering Research Council of Canada.