Effect of heterologous xylose transporter expression in Candida tropicalis on xylitol production rate

Xylose utilization is inhibited by glucose uptake in xylose-assimilating yeasts, including Candida tropicalis, resulting in limitation of xylose uptake during the fermentation of glucose/xylose mixtures. In this study, a heterologous xylose transporter gene (At5g17010) from Arabidopsis thaliana was selected because of its high affinity for xylose and was codon-optimized for functional expression in C. tropicalis. The codon-optimized gene was placed under the control of the GAPDH promoter and was integrated into the genome of C. tropicalis strain LXU1 which is xyl2-disrupted and NXRG (codon-optimized Neurospora crassa xylose reductase) introduced. The xylose uptake rate was increased by 37–73 % in the transporter expression-enhanced strains depending on the glucose/xylose mixture ratio. The recombinant strain LXT2 in 500-mL flask culture using glucose/xylose mixtures showed a xylose uptake rate that was 29 % higher and a xylitol volumetric productivity (1.14 g/L/h) that was 25 % higher than the corresponding rates for control strain LXU1. Membrane protein extraction and Western blot analysis confirmed the successful heterologous expression and membrane localization of the xylose transporter in C. tropicalis.     

Early Diagnosis of Neurodegenerative Diseases – The Long Awaited Holy Grail and Bottleneck of Modern Brain Research – 19th HUPO BPP Workshop

The HUPO Brain Proteome Project (HUPO BPP) held its 19th workshop in Dortmund, Germany, from May 22 to 24, 2013. The focus of the spring workshop was on strategies and developments concerning early diagnosis of neurodegenerative diseases     

Rapid identification of potential drought tolerance genes from Solanum tuberosum by using a yeast functional screening method

Identification of major stress tolerance genes of a crop plant is important for the rapid development of its stress-tolerant cultivar. Here, we used a yeast functional screen method to identify potential drought-tolerance genes from a potato plant. A cDNA expression library was constructed from hyperosmotic stressed potato plants. The yeast transformants expressing different cDNAs were selected for their ability to survive in hyperosmotic stress conditions. The relative tolerances of the selected yeast transformants to multiple abiotic stresses were also studied. Specific potato cDNAs expressed in the tolerant yeast transformants were identified. Sixty-nine genes were found capable of enhancing hyperosmotic stress tolerance of yeast. Based on the relative tolerance data generated, 12 genes were selected, which could be most effective in imparting higher drought tolerance to potato with better survival in salt and high-temperature stresses. Orthologues of few genes identified here are previously known to increase osmotic stress tolerance of yeast and plants; however, specific studies are needed to confirm their role in the osmotic stress tolerance of potato.     

后侧手术入路、锁定钢板固定治疗胫骨平台后髁骨折的临床疗效

目的：探讨采用膝关节后内和后外侧切口、锁定钢板固定治疗胫骨平台后髁骨折的临床疗效。方法：选取2009年1月～2011年12月来我院治疗的13例胫骨平台后髁骨折患者作为研究对象,所有患者采用后内和后外侧切口、锁定钢板固定治疗,观察术后骨折愈合情况,采用Rasmussen放射学评分评定骨折复位情况,采用HSS评分系统评定膝关节功能疗效。结果：术后随访6～24个月,平均13．6个月,所有患者骨折均于16周内愈合。Rasmussen放射学评分15～18分,平均17．4分,其中优8例,良3例,可2例,优良率为84．7％。末次随访时膝关节功能HSS评分73~97分,平均91．4分,其中获优7例,良5例,可1例,优良率为92．3％。结论：采用膝关节后内和（或）后外侧切口、锁定钢板固定治疗胫骨平台后髁骨折具有操作简单、显露清晰、直视下复位骨折及关节面、固定牢靠、利于早期功能锻炼、临床疗效确切、并发症少等优点。     

西瓜DUS测试标准品种SSR指纹图谱构建及应用

本研究采用代表最大限度西瓜遗传多样性的SSR核心引物组合,分析了西瓜DUS测试指南中的24份标准品种遗传多样性与核酸指纹。以基于重测序获得的SNP标记构建的17份西瓜材料的系统发育树为参照,对24份标准品种进行了遗传多样性分析,在遗传相似系数0.80处将24份标准品种分为3大类群,分析表明：核酸指纹分类比传统形态学分类更为准确。采用二维（QR）编码构建了西瓜24份标准品种的SSR指纹图谱,并利用本技术以保护品种“京欣2号”与对照品种“京欣1号”为例,进行了DUS分子鉴定测试,共扩增32个SSR位点,“京欣1号”和“京欣2号”之间存在4个位点的差异,品种间遗传相似系数为0.89,比形态学鉴定的差异位点更多且更准。本研究建立的西瓜DUS标准品种SSR指纹图谱与分子检测技术,可以应用到西瓜品种DUS分子检测实践,同时也为西瓜品种纯度与真实性鉴定及遗传背景分析提供了技术方案。     

Highest Efficiency Plasmonic Polycrystalline Silicon Thin-Film Solar Cells by Optimization of Plasmonic Nanoparticle Fabrication

Excitation of surface plasmons in metallic nanoparticles is a promising method for increasing the light absorption in solar cells and hence the cell photocurrent. Comprehensive optimization of a nanoparticle fabrication process for enhanced performance of polycrystalline silicon thin-film solar cells is presented. Three factors were studied: the Ag precursor film thickness, annealing temperature and time. The thickness of the precursor film was 10, 14 and 20 nm; annealing temperature was 190, 200, 230 and 260 °C; and annealing time was varied between 20 and 95 min. Performance enhancement due to light-scattering by nanoparticles was calculated by comparing absorption, short-circuit current density and energy conversion efficiency in solar cells with and without nanoparticles formed under different process conditions. Nanoparticles formed from 14-nm-thick Ag precursor film annealed at 230 °C for 53 min result in the highest absorption enhancement in the 700–1,100 nm wavelength range, in the highest enhancement of total short-circuit current density. The highest photocurrent enhancement was 33.5 %, which was achieved by the cell with the highest absorption enhancement in the 700–1,100 nm range. The plasmonic cell efficiency of 5.32 % was achieved without a back reflector and 5.95 % with the back reflector; which is the highest reported efficiency for plasmonic thin-film solar cells.     

Optimization of Dielectric-Coated Silver Nanoparticle Films for Plasmonic-Enhanced Light Trapping in Thin Film Silicon Solar Cells

Surface plasmonic-enhanced light trapping from metal nanoparticles is a promising way of increasing the light absorption in the active silicon layer and, therefore, the photocurrent of the silicon solar cells. In this paper, we applied silver nanoparticles on the rear side of polycrystalline silicon thin film solar cell and systematically studied the dielectric environment effect on the absorption and short-circuit current density (Jsc) of the device. Three different dielectric layers, magnesium fluoride (MgF₂, n?=?1.4), tantalum pentoxide (Ta₂O₅, n?=?2.2), and titanium dioxide (TiO₂, n?=?2.6), were investigated. Experimentally, we found that higher refractive index dielectric coatings results in a redshift of the main plasmonic extinction peak and higher modes were excited within the spectral region that is of interest in our thin film solar cell application. The optical characterization shows that nanoparticles coated with highest refractive index dielectric TiO₂ provides highest absorption enhancement 75.6 %; however, from the external quantum efficiency characterization, highest short-circuit current density Jsc enhancement of 45.8 % was achieved by coating the nanoparticles with lower refractive index MgF₂. We also further optimize the thickness of MgF₂ and a final 50.2 % Jsc enhancement was achieved with a 210-nm MgF₂ coating and a back reflector.     

Wheat seed proteins regulated by imbibition independent of dormancy status

Seed dormancy is an important trait in wheat (Trticum aestivum L.) and it can be released by germination-stimulating treatments such as after-ripening. Previously, we identified proteins specifically associated with after-ripening mediated developmental switches of wheat seeds from the state of dormancy to germination. Here, we report seed proteins that exhibited imbibition induced co-regulation in both dormant and after-ripened seeds of wheat, suggesting that the expression of these specific proteins/protein isoforms is not associated with the maintenance or release of seed dormancy in wheat.     

ScFKBP12 bridges rapamycin and AtTOR in Arabidopsis

FKBP12 encodes a prolyl isomerase and highly conserved in eukaryotic species. In yeasts and animals, FKBP12 can interact with rapamycin and FK506 to form rapamycin-FKBP12 and FK506-FKBP12 complex, respectively. In higher plants, FKBP12 protein lost its function to bind rapamycin and FK506. Early studies showed that yeast and human FKBP12 protein can restore the rapamycin sensitivity in Arabidopsis, but the used concentration is 100–1000 folds higher than that in yeast and animals. High concentration of drugs would increase the cost and cause the potential secondary effects on plant growth and development. Here we further discovered that BP12 plants generated in our previous study are hypersensitive to rapamycin at the concentration as low as that is effective in yeast and animals. It is surprising to observe that WT and BP12 plants are not sensitive to FK506 in normal growth condition. These findings advance the current understanding of rapamycin-TOR signaling in plants.