黄麻两个栽培种及其野生类型与三个近缘种的核型分析

本研究选取黄麻属（Corchorus）2个栽培品种及其4个野生类型和3个野生近缘种为材料,采用常规根尖压片法对黄麻属供试材料的染色体数目和核型进行研究。结果表明：染色体数目均为2n=14。核型公式分别为：宽叶长果（长果黄麻栽培种）2n=2x=14=14m(4SAT);南阳野生长果（长果黄麻野生类型）2n=2x=14=14m(2SAT);坦桑尼亚野生长果（长果黄麻野生类型）2n=2x=14=2M+12m;闽麻5号（圆果黄麻栽培种）2n=2x=14=12m+2sm;爱店野生圆果（圆果黄麻野生类型）2n=2x=14=14m ;廉江野生圆果（圆果黄麻野生类型） 2n=2x=14=4M+10m;假黄麻（黄麻属野生近缘种）2n=2x=14=2M+12m;假长果（黄麻属野生近缘种）2n=2x=14=2M+12m;甜麻（黄麻属野生近缘种）2n=2x=14=14m。其中除了宽叶长果核型分类为1B外,其他的都为1A型。本文还讨论了黄麻野生近缘种甜麻的分类学地位。     

克拉维酸生产中废乙酸乙酯的紫外扫描评价方法及树脂处理

建立克拉维酸生产中废乙酸乙酯的快捷评价方法。采用紫外吸收扫描,以吸收面积作为评价指标,全面评价废乙酸乙酯中的杂质残留。选用不同的树脂吸附处理废乙酸乙酯。结果表明:废乙酸乙酯经FPA90Cl树脂吸附处理后,紫外吸收面积最小,仅有225.601±5.499,残留的杂质最少。经条件优化后,批处理量为60 m3废乙酸乙酯的树脂用于克拉维酸生产,产品质量与新乙酸乙酯生产的产品质量相近。使用树脂处理废乙酸乙酯可减轻乙酸乙酯蒸馏回收和环保的压力,降低生产成本,具有良好的经济效益和环境效益。     

绝经后女性心血管危险因素与骨密度的相关关系

目的:本研究的目的是评估绝经后女性冠心病患者心血管危险因素与骨密度的相关关系。方法:评估216例拟行冠脉造影的绝经后女性冠心病患者的危险因素,并于冠脉造影检查前日或次日行骨密度检测,依据T值将受试者分为2组:骨量正常组(T值大于-1SD)、低骨量组(T值小于-1SD)。结果:2组患者在BMI、糖尿病、高血压及吸烟等均无显著性差异。低骨量组冠心病的发生率及年龄显著高于骨量正常组。Logistic回归分析显示绝经后女性冠心病患者年龄与骨密度独立相关(OR=1.072 CI:1.036～1.11p=0.001)。结论:年龄与绝经后女性冠心病患者骨密度负相关,心血管病危险因素或冠心病与骨量不相关。     

Biodiesel production using Aspergillus niger as a whole‐cell biocatalyst in a packed‐bed reactor

Enzymatic lipase transesterification of palm oil to biodiesel in a packed‐bed reactor (PBR) using a novel strain of the fungus Aspergillus niger, immobilized within polyurethane biomass support particles (BSPs), was investigated. A three‐step addition of methanol was used to reduce lipase inhibition by immiscible methanol. The influence of water content and PBR flow rate was investigated. FAME yield was enhanced with an increase of PBR flow rate in the range of 0.15–30 L h^?1, where inefficient mixing of the reaction mixture at lower flow rates resulted in low conversion rates i.e. 69% after 72‐h reaction. Adding the third mole equivalent of methanol resulted in lipase inhibition due to methanol migration into the accumulated glycerol layer. Glutaraldehyde (GA) solution (0.5 vol.%) was used to stabilize lipase activity, which led to a high FAME yield (>90%) in the PBR after 72‐h of reaction time at a flow rate of 15 L h^?1, and a water content of 15%. Moreover, a high conversion rate (>85%) was maintained after four palm oil batch conversion cycles in the PBR. In contrast, lipase activity of non‐GA‐treated cells decreased with each PBR batch cycle, where only 70% FAME was produced after the forth PBR cycle. Transesterification of palm oil in a PBR system using BSPs‐immobilized A. niger as a whole‐cell biocatalyst is a viable process for enzymatic biodiesel production.     

Human anti-V3 HIV-1 monoclonal antibodies encoded by the VH5-51/VL lambda genes define a conserved antigenic structure

Preferential usage of immunoglobulin (Ig) genes that encode antibodies (Abs) against various pathogens is rarely observed and the nature of their dominance is unclear in the context of stochastic recombination of Ig genes. The hypothesis that restricted usage of Ig genes predetermines the antibody specificity was tested in this study of 18 human anti-V3 monoclonal Abs (mAbs) generated from unrelated individuals infected with various subtypes of HIV-1, all of which preferentially used pairing of the VH5-51 and VL lambda genes. Crystallographic analysis of five VH5-51/VL lambda-encoded Fabs complexed with various V3 peptides revealed a common three dimensional (3D) shape of the antigen-binding sites primarily determined by the four complementarity determining regions (CDR) for the heavy (H) and light (L) chains: specifically, the H1, H2, L1 and L2 domains. The CDR H3 domain did not contribute to the shape of the binding pocket, as it had different lengths, sequences and conformations for each mAb. The same shape of the binding site was further confirmed by the identical backbone conformation exhibited by V3 peptides in complex with Fabs which fully adapted to the binding pocket and the same key contact residues, mainly germline-encoded in the heavy and light chains of five Fabs. Finally, the VH5-51 anti-V3 mAbs recognized an epitope with an identical 3D structure which is mimicked by a single mimotope recognized by the majority of VH5-51-derived mAbs but not by other V3 mAbs. These data suggest that the identification of preferentially used Ig genes by neutralizing mAbs may define conserved epitopes in the diverse virus envelopes. This will be useful information for designing vaccine immunogen inducing cross-neutralizing Abs.     

Metabolic patterns and biotransformation activities of resveratrol in human glioblastoma cells: relevance with therapeutic efficacies

Background

Trans-resveratrol rather than its biotransformed monosulfate metabolite exerts anti-medulloblastoma effects by suppressing STAT3 activation. Nevertheless, its effects on human glioblastoma cells are variable due to certain unknown reason(s).

Methodology/Principal Findings

Citing resveratrol-sensitive UW228-3 medulloblastoma cell line and primarily cultured rat brain cells/PBCs as controls, the effect of resveratrol on LN-18 human glioblastoma cells and its relevance with metabolic pattern(s), brain-associated sulfotransferase/SULT expression and the statuses of STAT3 signaling and protein inhibitor of activated STAT3 (PIAS3) were elucidated by multiple experimental approaches. Meanwhile, the expression patterns of three SULTs (SULT1A1, 1C2 and 4A1) in human glioblastoma tumors were profiled immunohistochemically. The results revealed that 100 µM resveratrol-treated LN-18 generated the same metabolites as UW228-3 cells, while additional metabolite in molecular weight of 403.0992 in negative ion mode was found in PBCs. Neither growth arrest nor apoptosis was found in resveratrol-treated LN-18 and PBC cells. Upon resveratrol treatment, the levels of SULT1A1, 1C2 and 4A1 expression in LN-18 cells were more up-regulated than that expressed in UW228-3 cells and close to the levels in PBCs. Immunohistochemical staining showed that 42.0%, 27.1% and 19.6% of 149 glioblastoma cases produced similar SULT1A1, 1C2 and 4A1 levels as that of tumor-surrounding tissues. Unlike the situation in UW228-3 cells, STAT3 signaling remained activated and its protein inhibitor PIAS3 was restricted in the cytosol of resveratrol-treated LN-18 cells. No nuclear translocation of STAT3 and PIAS3 was observed in resveratrol-treated PBCs. Treatment with STAT3 chemical inhibitor, AG490, committed majority of LN-18 and UW228-3 cells but not PBCs to apoptosis within 48 hours.

Conclusions/Significance

LN-18 glioblastoma cells are insensitive to resveratrol due to the more inducible brain-associated SULT expression, insufficiency of resveratrol to suppress activated STAT3 signaling and the lack of PIAS3 nuclear translocation. The findings from PBCs suggest that an effective anticancer dose of resveratrol exerts little side effect on normal brain cells.     

化感水稻种质资源鉴定及基因定位研究进展与展望

稻种资源化感作用的鉴定评价与深入研究是化感水稻品种选育的基础.本文概要介绍了化感水稻种质资源鉴定评价方法、化感作用生理生化机理以及化感特性遗传与基因定位方面的主要研究进展,并进一步讨论了水稻化感作用研究与利用的发展方向.     

Effects of pH and calcium ions on the conformational transitions in silk fibroin using 2D Raman correlation spectroscopy and 13C solid-state NMR

Silk fibroin exists in a number of different states, such as silk I and silk II, with different properties largely defined by differences in secondary structure composition. Numerous attempts have been made to control the transitions from silk I to silk II in vitro to produce high-performance materials. Of all the factors influencing the structural compositions, pH and some metal ions play important roles. This paper focuses on the influence of pH and Ca(2+) ions on the conformational transition from silk I to silk II in regenerated (redissolved) Bombyx mori fibroin. One- and two-dimensional correlation Raman spectroscopy was used to describe qualitatively the transitions in secondary structure in silk I, silk II, and their intermediates as pH and Ca(2+) ion concentration were changed, while (13)C cross polarization magic angle spinning (CP/MAS) solid-state NMR was used to quantify these changes. We showed that conditions (low pH, pH 5.2; a defined range of Ca(2+) ion concentrations; gradual water removal) that mimic natural silk spinning promote the formations of beta-sheet and distorted beta-sheet characteristic of silk II or silk II-related intermediate. In contrast, higher pH (pH 6.9-8.0) and higher Ca(2+) ion concentrations maintain "random coil" conformations typical of silk I or silk I-related intermediate. These results help to explain why the natural silk spinning process is attended by a reduction in pH from 6.9 to 4.8 and a change in the Ca(2+) ion concentration in the gland lumen as fibroin passes from the posterior division through the secretory pathway to the anterior division.     

Single live cell imaging of chromosomes in chloramphenicol-induced filamentous Pseudomonas aeruginosa

Pseudomonas aeruginosa is a leading opportunistic pathogen in human infections, and it is renowned for its intrinsic resistance to structurally and functionally unrelated antibiotics. Filamentation induced by antibiotics appears to trigger bacteria to depart from a normal growth phase and enter a stationary growth phase. As antibiotic concentrations decline below a therapeutic range, filamentous bacteria begin to divide normally, leading to a more rapid regrowth of the bacteria. Furthermore, filamentous bacteria are associated with an increase in endotoxin release. Moreover, the immune system of a patient needs to cope with uncharacteristic filamentous bacteria. Thus, it is biologically and clinically significant to study and understand bacterial filamentation. In this study, we investigate the frequencies, conditions, and characteristics of a filamentous P. aeruginosa at single cell and single chromosome resolutions. Our results show that filamentous cells (elongated rods) contain multiple copies of the cell's chromosome. It appears that the unsuccessful segregation of replicated chromosomes in an individual cell accompanies the formation of undivided filamentous cells. The quantity of chromosomes and the length of the filamentous wild-type cells increase as the chloramphenicol concentration increases to 50 and 250 microg/mL, suggesting that chloramphenicol induces the filamentation. Filamentation in three strains of P. aeruginosa depends on the expression level of efflux pump (MexAB-OprM) and the minimum inhibitory concentration of chloramphenicol. This study also opens up the new possibility of real-time monitoring of modes of actions of antibiotics in live cells with both temporal and spatial resolution.     

Using nanoparticle optics assay for direct observation of the function of antimicrobial agents in single live bacterial cells

Multidrug resistance (MDR) has been reported in both prokaryotes and eukaryotes, underscoring the challenge of design and screening of more efficacious new drugs. For instance, the efflux pump of Pseudomonas aeruginosa (gram-negative bacteria) can extrude a variety of structurally and functionally diverse substrates, which leads to MDR. In this study, we present a new platform that studies modes of action of antibiotics in living bacterial cells (P. aeruginosa), in real-time, at nanometer scale and single-cell resolution using nanoparticle optics and single living cell imaging. The color index of silver (Ag) nanoparticles (violet, blue, green, and red) is used as the sized index (30 +/- 10, 50 +/- 10, 70 +/- 10, and 90 +/- 10 nm) for real-time measurement of sized transformation of the cell wall and membrane permeability at the nanometer scale. We have demonstrated that the number of Ag nanoparticles accumulated in cells increases as the aztreonam (AZT) concentration increases and as incubation time increases, showing that AZT induces the sized transformation of membrane permeability and the disruption of the cell wall. The results demonstrate that nanoparticle optics assay can be used as a new powerful tool for real-time characterization of modes of action of antimicrobial agents in living cells at the nanometer scale. Furthermore, studies of mutants of WT bacteria (nalB-1 and DeltaABM), suggest that an efflux pump (MexA-MexB-OprM) effectively extrudes substrates (nanoparticles) out of the cells, indicating that the MDR mechanism involves the induction of changes in membrane permeability and the intrinsic pump machinery.