Antifungal peptides: a potential new class of antifungals for treating vulvovaginal candidiasis caused by fluconazole‐resistant Candida albicans

Vulvovaginal candidiasis/candidosis is a common fungal infection afflicting approximately 75% of women globally caused primarily by the yeast Candida albicans. Fluconazole is widely regarded as the antifungal drug of choice since its introduction in 1990 due to its high oral bioavailability, convenient dosing regimen and favourable safety profile. However, its widespread use has led to the emergence of fluconazole‐resistant C. albicans, posing a universal clinical concern. Coupled to the dearth of new antifungal drugs entering the market, it is imperative to introduce new drug classes to counter this threat. Antimicrobial peptides (AMPs) are potential candidates due to their membrane‐disrupting mechanism of action. By specifically targeting fungal membranes and being rapidly fungicidal, they can reduce the chances of resistance development and treatment duration. Towards this goal, we conducted a head‐to‐head comparison of 61 short linear AMPs from the literature to identify the peptide with the most potent activity against fluconazole‐resistant C. albicans. The 11‐residue peptide, P11‐6, was identified and assayed against a panel of clinical C. albicans isolates followed by fungicidal/static determination and a time‐kill assay to gauge its potential for further drug development. Copyright © 2017 European Peptide Society and John Wiley & Sons, Ltd.     

An improved method for Beauveria bassiana transformation using phosphinothricin acetlytransferase and green fluorescent protein fusion gene as a selectable and visible marker

An improved transformation method for the biocontrol agent, Beauveria bassiana, was developed. For convenience of transformation selection and detection, the coding regions of the genes for phosphinothricin acetyltransferase and green fluorescent protein were fused and an expression vector, pBFT, carrying this fusion was constructed. Under optimum conditions, over 60 transformants microg(-1) plasmid DNA were obtained. B. bassiana conidia frozen 1 month at -80 degrees C were fully competent for transformation. The method was significantly less laborious and more rapid than current methods for B. bassiana. The bar::egfp provides a selectable and visible marker which may expedite future genetic engineering of this fungus.     

下调TLR4对LPS诱导的支气管上皮16HBE细胞损伤的影响及其机制

目的探讨TLR4对脂多糖（LPS）诱导的支气管上皮16HBE细胞损伤的影响及其机制。 方法将3条siRNA-TLR4-1、siRNA-TLR4-2和siRNA-TLR4-3转染至16HBE细胞中,筛选出最佳的siRNA-TLR4干扰序列进行实验。实验分为对照组（未处理）、LPS组（给予50 μg/ml LPS处理）、LPS+siNC组（转染siRNA-NC后给予50 μg/ml LPS处理）和LPS+siTLR4组（分别转染设计的3条siRNA-TLR4后给予50 μg/ml LPS处理）,采用RT-PCR检测TLR4、IL-6和TNF-α mRNA的表达,MTT法检测细胞活力,流式细胞仪检测细胞凋亡率,Western Blot检测Bcl-2、Bax、Cleaved Caspase-3、NF-κB p65和IκBα蛋白的表达。多组间比较使用单因素方差分析,组间多重比较采用SNK-q,两组间比较采用独立样本t检验。 结果LPS组与LPS+siTLR4-2组TLR4 mRNA（2.05±0.12,3.28±0.15）和蛋白表达（0.38±0.03,0.77±0.05）比较,差异具有统计学意义（t?= 11.091,11.585,P均< 0.001）;LPS组与LPS+siTLR4-3组TLR4 mRNA（1.39±0.09,3.28±0.15）和蛋白表达（0.31±0.02,0.77±0.05）比较,差异具有统计学意义（t?= 20.857,12.650,P均?< 0.001）且siRNA-TLR4-3的效果最为显著。与对照组相比,LPS组、LPS+siNC组和LPS+siTLR4组细胞中IL-6 mRNA（11.42±1.05,11.38±1.34,6.22±0.35,0.97±0.06,F?= 98.803,P均< 0.01）、TNF-α mRNA（15.76±1.12,15.69±0.87,7.54±0.41,1.03±0.09,F?= 278.064,P均< 0.01）、Cleaved Caspase-3蛋白（0.75±0.06,0.77±0.05,0.38±0.03,0.13±0.02,F?= 154.851,P均< 0.01）、Bax蛋白（0.48±0.05,0.52±0.05,0.33±0.02,0.11±0.02,F?= 71.310,P均< 0.01）、NF-κBp65蛋白（0.64±0.05,0.67±0.05,0.45±0.04,0.28±0.02,F?= 56.571,P?均?< 0.01）的表达水平和细胞凋亡率[（21.36±2.85）﹪,（20.94±3.22）﹪,（13.08±1.16）?﹪,（7.25±1.28）﹪,F?= 25.685,P均< 0.01]均明显升高,而细胞活力（0.53±0.04,0.51±0.04,0.78±0.06,1.15±0.08,F?= 80.811,P均< 0.01）和Bcl-2蛋白（0.28±0.03,0.25±0.03,0.40±0.03,0.69±0.06,F?= 76.762,P均< 0.01）、IκBα蛋白（0.38±0.03,0.35±0.03,0.44±0.03,0.72±0.06,F?= 53.635,P均< 0.01）的表达水平均明显降低;与LPS组相比,LPS+siTLR4组中IL-6 mRNA、TNF-α mRNA、Cleaved Caspase-3蛋白、Bax蛋白、NF-κBp65蛋白的表达水平和细胞凋亡率均明显降低,差异有统计学意义（t = 8.138,11.937,9.553,4.825,5.140,4.661,P均< 0.01）,而细胞活力和Bcl-2蛋白、IκBα蛋白的表达水平均明显升高,差异有统计学意义（t = 6.005,4.899,3.674,P < 0.05）,而LPS组和LPS+siNC组间差异无统计学意义（P > 0.05）。 结论下调TLR4可通过抑制NF-κB通路激活抑制LPS诱导的细胞凋亡和炎症反应减轻16HBE细胞损伤。     

Inference of individual ploidy level using codominant markers

A significant portion of plant species are polyploids, with ploidy levels sometimes varying among individuals and/or populations. Current techniques to determine the individual ploidy, e.g., flow cytometry, chromosome counting or genotyping‐by‐sequencing, are often cumbersome. Based on the genotypic probabilities for polysomic inheritance under double‐reduction, we developed a model to estimate allele frequency and infer the ploidy status of individuals from the allelic phenotypes of codominant genetic markers. The allele frequencies are estimated by an expectation‐maximization algorithm in the presence of null alleles, false alleles, negative amplifications and self‐fertilization, and the posterior probabilities are used to assign individuals into different levels of ploidy. The accuracy of this method under different conditions is evaluated. Our methods are freely available in a new software package, ploidyinfer , for use by other researchers which can be downloaded from http://github.com/huangkang1987/ploidyinfer .     

Calcium Oxalate Crystals: An Integral Component of the Sclerotinia sclerotiorum/Brassica carinata Pathosystem

Oxalic acid is an important virulence factor for disease caused by the fungal necrotrophic pathogen Sclerotinia sclerotiorum, yet calcium oxalate (CaOx) crystals have not been widely reported. B. carinata stems were infected with S. sclerotiorum and observed using light microscopy. Six hours post inoculation (hpi), CaOx crystals were evident on 46% of stem sections and by 72 hpi on 100%, demonstrating that the secretion of oxalic acid by S. sclerotiorum commences before hyphal penetration. This is the first time CaOx crystals have been reported on B. carinata infected with S. sclerotiorum. The shape of crystals varied as infection progressed. Long tetragonal rods were dominant 12 hpi (68% of crystal-containing samples), but by 72 hpi, 50% of stems displayed bipyramidal crystals, and only 23% had long rods. Scanning electron microscopy from 24 hpi revealed CaOx crystals in all samples, ranging from tiny irregular crystals (< 0.5 μm) to large (up to 40 μm) highly organized arrangements. Crystal morphology encompassed various forms, including tetragonal prisms, oval plates, crystal sand, and druses. Large conglomerates of CaOx crystals were observed in the hyphal mass 72 hpi and these are proposed as a strategy of the fungus to hold and detoxify Ca²⁺ions. The range of crystal morphologies suggests that S. sclerotiorum growth and infection controls the form taken by CaOx crystals.     

Enhancement of human ACAT1 gene expression to promote the macrophage-derived foam cell formation by dexamethasone

In macrophages, the accumulation of cholesteryl esters synthesized by the activated acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT1) results in the foam cell formation, a hallmark of early atherosclerotic lesions. In this study, with the treatment of a glucocorticoid hormone dexamethasone (Dex), lipid staining results clearly showed the large accumulation of lipid droplets containing cholesteryl esters in THP-1-derived macrophages exposed to lower concentration of the oxidized low-density lipoprotein (ox-LDL). More notably, when treated together with specific anti-ACAT inhibitors, the abundant cholesteryl ester accumulation was markedly diminished in THP-1-derived macrophages, confirming that ACAT is the key enzyme responsible for intracellular cholesteryl ester synthesis. RT-PCR and Western blot results indicated that Dex caused up-regulation of human ACAT1 expression at both the mRNA and protein levels in THP-1 and THP-l-derived macrophages. The luciferase activity assay demonstrated that Dex could enhance the activity of human ACAT1 gene P1 promoter, a major factor leading to the ACAT1 activation, in a cell-specific manner. Further experimental evidences showed that a glucocorticoid response element (GRE) located within human ACAT1 gene P1 promoter to response to the elevation of human ACAT1 gene expression by Dex could be functionally bound with glucocorticoid receptor (GR) proteins. These data supported the hypothesis that the clinical treatment with Dex, which increased the incidence of atherosclerosis, may in part due to enhancing the ACAT1 expression to promote the accumulation of cholesteryl esters during the macrophage-derived foam cell formation, an early stage of atherosclerosis.     

Perivascular epithelioid cell tumor (PEComa) of the uterine cervix associated with intraabdominal "PEComatosis": A clinicopathological study with comparative genomic hybridization analysis

Background  

The World Health Organization recently recognized a family of neoplasms showing at least partial morphological or immunohistochemical evidence of a putative perivascular epithelioid cell (PEC) differentiation. These tumors include angiomyolipoma (AML), clear cell "sugar" tumors of the lung (CCST), lymphangioleiomyomatosis (LAM), clear cell myomelanocytic tumors of the falciform ligament and distinctive clear cell tumors at various other anatomic sites.     

Crystal structure and nmr conformation of a cyclic pseudotetrapeptide containing urethane backbone linkages

Urethane bonds, derived from the hydroxyl group of the tyrosine side chain, have been investigated as a new type of amide bond mimetic in the design of pseudopeptides. The structure of a representative cyclic pseudotetrapeptide that consists of an — Ala — Tyr(urethane) Ala — Tyr (urethane) sequence fused into a rigid ring has been studied in the solid state by x-ray crystallography and in solution by two-dimensional nmr techniques. The cyclic pseudotetrapeptide has an oblong shape. The backbone urethane bonds assume a trans–trans conformation. The carbonyl groups in the ring have an alternating pattern of down, up, down, up with respect to the average ring plane. Solution nmr studies give observed nuclear Overhauser effects and coupling constants largely in agreement with the crystal structure. However, in solution the observed structure is likely to be conformationally averaged, and in the averaged structure, the urethane bond is perpendicular to the plane of the aromatic ring of the tyrosine, while in the crystal it is close to this plane. These differences may be explained by intermolecular hydrogen-bonding interactions. Four aspects of the conformation of the cyclic pseudotetrapeptide were investigated in detail: the tyrosine residue with the attached side-chain urethane bond (the tyrosine-urethane unit), the conformation of the two urethane backbone linkages, the conformation of the two conventional peptide bonds within this unusual ring structure, and the tight turns within the cyclic pseudotetrapeptide. The conformation of the tight turns present in the cyclic pseudotetrapeptide is very similar to that of a β-bend of type II. Intermolecular hydrogen bonding, joining adjacent layers of the cyclic pseudotetrapeptide in the solid state, resemble a parallel β-pleated sheet. The presence of these structural motifs in the cyclic pseudotetrapeptide indicates that the tyrosine urethane unit may find applications in peptide and protein engineering. © 1994 John Wiley & Sons, Inc.     

黑河流域高寒草甸生态系统水分收支及蒸散发拆分研究

水分收支是对水循环要素降水、蒸发蒸腾、径流以及土壤贮储水量变化等的定量刻画,对水资源的可持续开发及利用至关重要。基于黑河流域阿柔观测站2014和2015年水文气象观测数据,运用水量平衡理论,定量的评估了高寒草甸生态系统的水分收支动态,并结合双源模型对高寒草甸生态系统蒸散发(植被蒸腾和土壤蒸发)进行拆分及评价。研究结果表明(1)在生长季(5—9月)植被蒸腾是高寒草甸生态系统主要的耗水形式,2014和2015年生长季平均蒸散比(T/ET)分别为0.74和0.79;(2)土壤水分的剧烈变化主要发生在0—40 cm处,且受冻融过程影响显著;(3)在降水较多的年份(2014)高寒草甸生态系统水分收支基本平衡,且不受冻融影响的月份(6—9)有地表径流产生约42 mm;在正常年份(2015),生态系统呈现水分亏缺,亏缺量约为134 mm,6—9月约亏缺26 mm;(4)模型估算蒸散发(ET)与实测蒸散发具有很好的一致性,相关系数可达0.90,敏感性分析表明模型输入变量对蒸散发(ET)及蒸散比(T/ET)产生的误差较小,双源模型可以很好地实现对高寒草甸生态系统蒸散发(ET)的拆分。