Structural characterization of a pectic polysaccharide from Nerium indicum flowers

A polysaccharide fraction, J6, was isolated from the hot-water extract of flowers of oleander Nerium indicum Mill., using ethanol precipitation, cetyltrimethylammonium bromide (CTAB) complexing, anion-exchange chromatography and gel permeation chromatography. J6 was found to contain l-rhamnose, l-arabinose, d-galactose, and d-galacturonic acid, in the ratio of 10.1:49.8:30.1:10.0. Its structure was investigated by methylation analysis, periodate oxidation, Smith degradation, partial acid hydrolysis, electrospray ionization mass spectrometry and NMR spectroscopic methods. It was found that J6 is an RG-I type polysaccharide, which contains a rhamnogalacturonan backbone, with various branches attached to O-4 of l-rhamnose. The branches probably involve (1 → 4)-β-d-galactan, branched l-arabino-(1 → 3)(1 → 6)-β-d-galactan, and (1 → 5)-α-l-arabinan. J6 stimulated NO production of macrophage RAW264.7 cells in a preliminary test.     

Diverse set of microRNAs are responsive to powdery mildew infection and heat stress in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Background  

MicroRNAs (miRNAs) are a class of small non-coding regulatory RNAs that regulate gene expression by guiding target mRNA cleavage or translational inhibition. MiRNAs can have large-scale regulatory effects on development and stress response in plants.     

An examination of targeted gene neighborhoods in strawberry

Background  

Strawberry (Fragaria spp.) is the familiar name of a group of economically important crop plants and wild relatives that also represent an emerging system for the study of gene and genome evolution. Its small stature, rapid seed-to-seed cycle, transformability and miniscule basic genome make strawberry an attractive system to study processes related to plant physiology, development and crop production; yet it lacks substantial genomics-level resources. This report addresses this deficiency by characterizing 0.71 Mbp of gene space from a diploid species (F. vesca). The twenty large genomic tracks (30-52 kb) captured as fosmid inserts comprise gene regions with roles in flowering, disease resistance, and metabolism.     

Knowledge and adherence to antiretroviral therapy among adult people living with HIV/AIDS treated in the health care centers of the association "Espoir Vie Togo" in Togo,West Africa

Background  

The efficiency of antiretroviral therapy (ART) depends on a near perfect level of patients' adherence. The level of adherence of adults HIV-infected patients treated in the HIV/AIDS health care centres of the association "Espoir Vie Togo" in Togo, West Africa is not properly documented. The aim of the present study was to examine by means of self-reports the knowledge, the adherence level and associated factors to antiretroviral therapy (ART) among these patients.     

Target-specific cellular uptake of taxol-loaded heparin-PEG-folate nanoparticles

To enhance site-specific intracellular delivery against folate receptor, heparin-PEG-folate (H-PEG-F) containing succinylated-heparin conjugated with folate via PEG 1000/3000 spacers has been prepared. Due to covalent strategy, H-PEG-F displays amphiphilic property, which is capable of entrapping a hydrophobic agent, like taxol, to form heparin-PEG-folate-taxol nanoparticles (H-PEG-F-T NPs) in aqueous solution. Hydrophobic agents can be entrapped within the core, while the H-PEG-F conjugates can stabilize the nanoparticles with exposing folate moieties on the surface. The structure of carrier and naoparticles has been characterized by(1)H NMR, and the content of folate and taxol has been quantitatively analyzed by UV method. The morphology and size of H-PEG-F-T NPs have been measured by field emission scanning electron microscopy (FESEM) and dynamic lighting scatter (DLS). All the NPs are in spherical shape and the sizes are less than 200 nm. The sizes of the NPs increases with increasing PEG segment length. By employing the flow cytomery method, the extent of cellular uptake has been comparatively evaluated under various conditions. The results of cellular uptake demonstrate that the cellular uptake of the carrier and the NPs is exceedingly higher for KB-3-1 cells (folate receptor overexpressing cell line) than for A549 cells (folate receptor deficiency cell line); H-PEG-F-T NPs show far greater extent of cellular uptake than that of H-PEG-F conjugates against A549 cells; when the content of folate is fixed at the same value, the extent of cellular uptake for the carrier and NPs ascends with the increase of PEG chain length against KB-3-1 cells. It suggests folate-receptor-mediated endocytosis and formation of nanoparticle and spacer length are considered to coaffect the cellular uptake efficiency of H-PEG-F-T NPs and H-PEG-F conjugates. Flow cytometry analysis depicts that KB-3-1 cells treated with H-PEG-F-T are arrested in the G(2)/M phase of the cell cycle, which states the similar inhibition mechanism as taxol. The strategy based on the formation of H-PEG-F-T NPs could be potentially applied for cancer cell targeted delivery of various therapeutic agents.     

布氏锥虫苯丙氨酰-tRNA合成酶在大肠杆菌中的克隆、表达、纯化及活性测定

苯丙氨酰-tRNA合成酶是布氏锥虫蛋白合成过程中的一类重要酶,以其为靶点的抑制剂可能发展成为新一代的抗锥虫药物,但此前并没有分离锥虫苯丙氨酸-tRNA合成酶的报道。本研究用大肠杆菌成功克隆表达并纯化了布氏锥虫苯丙氨酰-tRNA合成酶并进行了活性测定。首先通过PCR方法从布氏锥虫细胞基因组中分别扩增出苯丙氨酰-tRNA合成酶的α亚基、β亚基的基因,依次克隆入pCOLADuet共表达载体,然后在大肠杆菌BL21(DE3)RIPL中进行了成功表达,并采用Ni-Bind亲和层析对其进行了纯化,最后用免疫印迹进行了鉴定。此外还采用放射性同位素方法进行了酶活性测定,这为下一步进行布氏锥虫苯丙氨酰-tRNA合成酶抑制物的设计和体外筛选奠定了良好的基础。     

猪链球菌1、2、14、1/2型荚膜多糖的单糖组成比较

【目的】猪链球菌1、2、14和1/2型间存在单向或双向的交叉抗原性,这种交叉抗原性的产生原因至今未被揭示。【方法】采用Sephacryl S-300凝胶层析柱对猪链球菌14和1/2型荚膜多糖进行分离纯化,经苯酚-硫酸检测和dot-ELISA辅助鉴定,确定荚膜多糖成分。采用高效凝胶渗透色谱法测定14和1/2型猪链球菌荚膜多糖分子量分别为487.38 kDa和512.72 kDa。【结果】经柱前衍生高效液相色谱法、荧光标记液相色谱法和核磁共振测定14和1/2型猪链球菌荚膜多糖单糖组成分别为:Glc/Gal/GlcNAc/Rha/Neu5Ac(1∶2.94∶1.35∶0.24∶0.37)和Glc/Gal/GlcNAc/GalNAc/Rha/Neu5Ac(1∶1.67∶1.05∶0.93∶0.72∶0.7)。并与已知的猪链球菌1、2型荚膜多糖的单糖组成进行比较分析,发现4种血清型荚膜多糖都具有Glc、GlcNAc、Gal和Neu5Ac,但单糖组成和比列并无明显相似性,这种交叉抗原性可能是由于荚膜多糖的空间结构相似性和(或)细胞表面的其他成分引起的。     

地中海拟无枝菌酸菌U32染色体特性的脉冲场电泳分析

地中海拟无枝菌酸菌(Amycolatopsis mediterranei)U32是产力复霉素SV的工业生产菌株。采用脉冲场电泳分析发现,地中海拟无枝菌酸菌U32仅有一条约10 Mb的线性染色体, 没有内源性质粒。利用Southern杂交法,对11个编码力复霉素生物合成、相关初级、次级代谢关键酶以及调控蛋白的基因,在U32染色体DNA的PshBI酶切片段上进行了定位。分析发现在一条长度约700kb的PshBI酶切片段上,分别存在着力复霉素合成基因簇(rif)、氮代谢的亚硝酸还原酶小亚基基因(nasD)、衔接初级与次级代谢的甲基丙二酰变位酶基因(mcm)、脂肪酸代谢的乙酰辅酶A羧化酶生物素载体蛋白基因(accA)以及一套核糖体RNA转录单元。同时还发现U32至少有5套核糖体RNA转录单元。其余定位的基因均只出现单一杂交信号。     

Evaluation of Beauveria bassiana (Hyphomycetes) isolates as potential agents for control of Dendroctonus valens

Abstract The red turpentine beetle (RTB), Dendroctonus valens LeConte, as a destructive invasive pest, has become one of the most economically important forest pest in China. Effective control measures are desperately needed. Entomopathogenic fungi, such as Beauveria bassiana, have shown great potential for the management of some bark beetle species. In this study, 12 isolates of B. bassiana from bark beetle were examined for biological characteristics and virulence, to assess their potential as biocontrol agents for RTB. There were significant differences (at P= 0.05) in colony growth rate, conidial yield, conidial germination, tolerance to UV light and extracellular proteases activity among the tested B. bassiana isolates. Isolates, including Bb1801, Bb1906, Bb789 and Bb773, exhibited the best characteristics, because they have faster hyphal growth rate, higher spore production and faster spore germination, higher UV tolerance and protease (Pr1) production. The results of a pathogenicity test of B. bassiana on RTB larvae showed that most isolates of B. bassiana have demonstrated high efficacy and the highest virulent isolate was Bb1801, which killed 100% of the treated insects and had a median lethal time (LT₅₀) of 4.60 days at a concentration of 1×10⁷ conidia/mL. Therefore, isolate Bb1801 has a great potential for sustainable control of RTB in the forest. The correlation between biological characteristics and virulence of the fungal isolates is discussed and the possibility of combination of entomopathogenic fungi with semiochemicals, as one of the promising strategy for RTB control, is considered.