Numerical Investagation of a Castle-like Contour Plasmonic Nanoantenna with Operating Wavelengths Ranging in Ultraviolet–Visible, Visible Light, and Infrared Light

We propose a new design of a plasmonic nanoantenna and numerically study its optical properties by means of the 3D finite element method. The nanoantenna is composed of two identical castle-like contour nanometal-filled dielectric media inside the hollows. We examine the influence of the contour thickness, gap width, and dielectric media filled inside the hollows on the antenna resonance conditions. Through these simulations, we show that it is possible to tune an antenna with a constant length over a broad spectral range (ranging in ultraviolet–visible, visible light, and infrared light).     

Methylation profiling using degenerated oligonucleotide primer-PCR specific for genome-wide amplification of bisulfite-modified DNA

DNA methylation is one of the essential epigenetic processes that play a role in regulating gene expression. Aberrant methylation of CpG-rich promoter regions has been associated with many forms of human cancers. The current method for determining the methylation status relies mainly on bisulfite treatment of genomic DNA, followed by methylation-specific PCR (MSP). The difficulty in acquiring a methylation profiling often is limited by the amount of genomic DNA that can be recovered from a given sample, whereas complex procedures of bisulfite treatment further compromise the effective template for PCR analysis. To circumvent these obstacles, we developed degenerated oligonucleotide primer (DOP)-PCR to enable amplification of bisulfite-modified genomic DNA at a genome-wide scale. A DOP pair was specially designed as follows: first 3' DOP, CTCGAGCTGHHHHHAACTAC, where H is a mixture of base consisting of 50% A, 25% T, and 25% C; and second 5' DOP, CTCGAGCTGDDDDDGTTTAG, where D is a mixture of base consisting of 50% T, 25% G, and 25% A. Our results showed that bisulfite-modified DNAs from a cell line, cord blood cells, or cells obtained by laser capture microdissection were amplified by up to 1000-fold using this method. Subsequent MSP analysis using these amplified DNAs on nine randomly selected cancer-related genes revealed that the methylation status of these genes remained identical to that derived from the original unamplified template.     

Functional Contribution of Ca2+ and Mg2+ to the Intermolecular Interaction of Visinin-like Proteins

The interaction of human visinin-like protein 1 (VILIP1) and visinin-like protein 3 (VILIP3) with divalent cations (Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺) was explored using circular dichroism and fluorescence measurement. These results showed that the four cations each induced a different subtle change in the conformation of VILIPs. Moreover, VILIP1 and VILIP3 bound with Ca²⁺ or Mg²⁺ in a cooperative manner. Studies on the truncated mutants showed that the intact EF-3 and EF-4 were essential for the binding of VILIP1 with Ca²⁺ and Mg²⁺. Pull-down assay revealed that Ca²⁺ and Mg²⁺ enhanced the intermolecular interaction of VILIPs, and led to the formation of homo- and hetero-oligomer of VILIPs. Together with previous findings that Ca²⁺-dependent localization of VILIPs may be involved in the regulation of distinct cascades and deprivation of Ca²⁺-binding capacity of VILIPs did not completely eliminate their activity, it is likely to reflect that Mg²⁺-bound VILIPs may play a role in regulating the biological function of VILIPs in response to a concentration fluctuation of Ca²⁺ in cells.     

Recombinant dioscorins of the yam storage protein expressed in Escherichia coli exhibit antioxidant and immunomodulatory activities

Dioscorins, the major storage proteins in yam tubers, exhibit biochemical and immunomodulatroy activities. To investigate the potential application of dioscorins in biomedical research, we expressed the dioscorin genes Dj-dioA3 and Dp-dioA2 from Dioscorea japonica and Dioscorea pseudojaponica, respectively, in E. coli and routinely obtained approximately 15mg proteins per liter Escherichia coli culture (mg/L) to 30mg/L of rDj-dioscorinA3 and 4 to 8mg/L of rDp-dioscorinA2. Western blot analyses revealed that both recombinant dioscorins contained epitopes with similar antigenicities to those of the native dioscorins. Results from dithiothreitol (DTT) treatment followed by monobromobimane (mBBr) staining showed that both recombinant dioscorins, like the native dioscorins, contain an intramolecular disulfide bond between Cys(28) and Cys(187) residues. Circular dichroism spectroscopy findings indicated that the secondary structural contents of the recombinant dioscorins showed high similarity to those of their corresponding native dioscorins. Both recombinant dioscorins, like the native dioscorins, exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and Toll-like receptor 4 signaling activities, and stimulated the phagocytosis of E. coli by macrophage. Overall, our results indicated that substantial amounts of recombinant dioscorins can be purified easily from E. coli and that these recombinant dioscorins are appropriate for application in future investigations of the biomedical functions of dioscorins.     

Influencing effect of intra-granule mass transfer in expanded granular sludge-bed reactors treating an inhibitory substrate

Two expanded granular sludge-bed (EGSB) reactors (superficial velocity u s=6.0 and 9.0m/h) were used to treat an inhibitory substrate phenol. The granule diameter (dp) increased with increasing organic loading rate (OLR) and u(s). At the OLRs of 1.67-4.44 kg phenol/m3 d, the accumulation of volatile fatty acids (VFAs) was insignificant; whereas at the OLR of 5.11 kg phenol/m3 d, both the accumulation of VFAs and the washout of large hollow granules (average dp=2.90-3.12 mm) occurred. The comparative experimental and simulated results showed that the proposed kinetic model is suitable for design and predicting purposes. The calculation results of mass transfer parameters (Thiele modulus, Biot number, diffusion layer thickness, and overall effectiveness factor) and parametric sensitivity analysis results (half-saturation constant Ks and dp) showed that the intra-granule mass transfer would lead to a more influencing effect than the external mass transfer on the overall substrate removal rate in EGSB reactors.     

菌丝桥在日本落叶松幼苗间磷传递和植株生长中的作用

 应用四室隔网系统研究了菌丝桥在日本落叶松(Larix kaempferi)幼苗间传递磷的作用。结果表明,供体接种卷缘桩菇(Paxillus involutus)和彩色豆马勃（Pisolithus tinctorius）后,其外延菌丝可以穿过隔离层侵染受体落叶松,在供体和受体落叶松间形成了菌丝桥。供体植株接种菌根真菌后生物量明显增加,但是对受体植株没有显著的影响。菌根真菌侵染的供体和受体植株的根、地上部吸磷量均分别显著高于对照,而且供体植株根、地上部吸磷量增加的程度明显高于受体。被卷缘桩菇和彩色豆马勃侵染的受体植株体内32P的放射性强度分别是对照的10倍和6倍,两者形成菌丝桥后传递到受体植株的32P分别为供体植株体内32P的1.10%和0.22%。供体植株吸收的32P可以通过菌丝桥传递给受体,但是绝对数量十分有限,对受体植株磷营养没有产生显著的影响,但P. involutus和P. tinctorius侵染受体植株后,促进了受体落叶松对磷的吸收,这是菌丝桥形成后,真菌帮助受体植株吸收磷引起的。     

土壤中棉花黄萎病菌SYBR Green Ⅰ荧光RT-PCR定量检测技术研究

为实现田间土壤棉花黄萎病菌的早期检测,建立了土壤中棉花黄萎病菌的SYBR Green I荧光定量PCR检测方法。以含342bp PCR扩增产物的阳性质粒为参考,构建了标准曲线,并对该曲线的特异性、敏感性、可重复性进行了评价。结果表明,该方法具有快速、特异性强、敏感度高等特点。检测范围在3.8×103-3.8×108copies/μL之间有良好的线性关系,相关系数R2为0.996,扩增效率为101.5%,灵敏度比常规PCR方法高102倍。