甜叶菊斑枯病病原菌的生物学特性

甜叶菊斑枯病病原菌经鉴定为Septoria steviae Ishiba Yokoyama et Tani．,病菌分离菌株生长慢,在8种不同培养基上生长速度、产生分生孢子器和分生孢子的能力相差很大．光照对菌体产孢影响显,但对菌丝生长没有影响．降低马铃薯葡萄糖琼脂培养基中葡萄糖的含量,菌体生长慢,但可提高单位面积菌体产孢量．微量元素硼在一定范围内有促进产孢的作用．菌体在pH值3～10范围内均可生长,生长最适pH值是5．0～6．0．     

Fungicidal and spectral studies of some triphenyltin compounds

In the interest of developing a more effective fungicide to combat Dutch elm disease, our laboratories have synthesized several triphenyltin carboxylates and some 1:1 addition compounds of triphenyltin chloride using 2,3-disubstituted thiazolidin-4-ones as the ligand and screened them in vitro against Ceratocystis ulmi, the causative agent of Dutch elm disease, using a shake culture method. Elemental analyses and spectroscopic data indicate that the structures of the carboxy- lates in the solid state are monomeric with a tetrahedral tin atom with the exception of the furan-2-carboxylic acid derivative, which was found to be polymeric. The triphenyltin chloride adducts are trigonal-bipyramidal with the three phenyl groups in the equatorial plane. Far-infrared data indicate that the three phenyl groups are not co-planar. Screening results for both series of organotins indicate that these two classes of compounds are effective inhibitors of Ceratocystis ulmi, with the adducts having a higher activity. The furan-2-carboxylic acid derivative has a markedly decreased activity compared with the other carboxylates and this is attributed to its polymeric structure. © 1998 John Wiley & Sons, Ltd.     

Pseudomonas brassicacearum的数量分布差异及生物防治小麦全蚀病和油菜根腐病

通过3种PCR技术测定基因特征和测定3种生化特征,对来自南澳洲两块对比小麦田土壤中的Pseudomonas brassicacearum种群的菌株进行了分析研究.结果显示,两种不同土壤和两种不同根部区域(根表和根际),该种群具有高度多样性,其基因型和基因组也具有显著差异(P<0.05).所分离到的菌株中,四分之三具有独特的基因组,90%以上的基因组是其原种群所独具有的.所有菌株的基因组的平均同源性比较低(22%),聚类分析不能证明来自不同小麦田和不同根部区域的菌株具有亲缘性.聚类分析显示,种群内的基因流动是受到限制的,菌株基因组的差异是由于基因的随机漂流引起的,由根表得到的基因型是与所采集的对比土壤相关联的.有三分之一的菌株检测到了2,4-二乙酰基均苯三酚(PhlD)生物合成基因,这些菌株形成了一相关联的组群(同源性为60%).4株产生PhlD的菌株(两种野生型,表型不同)对小麦全蚀病和腐霉引起的油菜根腐病具有显著的防治效果,展现出了对这类病原菌引起的根部病害的防治潜能.     

MR findings of intestinal graft-versus-host disease

Graft-versus-host disease (GVHD) occurs as a complication of allogenic bone marrow transplantation (BMT). The disease is characterized by skin rash, jaundice, mucosal inflammation, and diarrhea. In this report, we describe magnetic resonance (MR) findings of intestinal GVHD, which is correlated with endoscopic biopsy. MR findings demonstrated generalized increased bowel wall thickness associated with substantial bowel wall enhancement with gadolinium chelate.     

神经元及神经环路活性异常与阿尔茨海默病研究进展

 细胞外淀粉样蛋白（Aβ）沉积和细胞内神经纤维缠结是阿尔茨海默病的典型病理特征。淀粉样蛋白和tau蛋白（神经纤维缠结的主要组成成分）在脑中的异常聚集会导致神经元活性异常,进而引起神经环路结构及功能紊乱,最终造成阿尔茨海默病患者认知功能障碍。概述了Aβ及tau蛋白的生成及调控,阐述了Aβ及tau蛋白异常聚集在神经元及神经环路活动中的作用和机制,综述了ApoE、炎症反应及成体神经发生异常在AD神经元及神经环路活动障碍中的作用。     

阿尔茨海默病研究进展

 综述了阿尔茨海默病（Alzheimer's disease,AD）发病机制的胆碱能假说、Aβ级联假说、免疫炎症学说、兴奋毒性学说和糖脂代谢学说等的研究进展;介绍了近几年发展起来的新的研究手段,如光遗传及冷冻电镜技术和光、磁、超声技术在AD研究及治疗领域的应用;提出应注重与其他跨界学科的交叉,如先进成像/检测技术、精准诊断和防治、可穿戴式物理治疗仪等。     

阿尔茨海默病的基因组学与功能基因组学研究进展

 阿尔茨海默病（AD）是最常见的神经退行性疾病与最主要的痴呆类型,其发病率随着年龄增加而呈指数式增长。随着人口老龄化,AD造成的社会经济负担愈趋严重。AD的遗传力接近80%,其人群易感程度、表型差异等性状特征受机体遗传变异的极大影响。总结了基于家系连锁分析、病例对照全基因组关联分析、全基因组测序等基因组学分析手段鉴定与AD发生发展相关的遗传变异与风险基因,梳理了基于各种组学数据的功能基因组学研究手段,解析遗传变异背后的调控元件、效应基因及其分子过程的研究进展。对风险基因及其转录与蛋白水平改变的揭示,可为AD的发病机制解析、药物开发、精准诊断与早期预测提供直接的靶点。     

ApoE4干扰大脑代谢诱发阿尔茨海默病

 阿尔茨海默病（AD）是导致老年人认知障碍的最主要疾病。AD也是主要的一种神经退行性疾病,其中约95%是晚发型AD（LOAD）。目前,LOAD的发病机制仍不清楚,但是,4型载脂蛋白E （ApoE ε4,ApoE4）是已知的最大风险基因。以临床及基础实验结果为证据,探讨了ApoE4导致大脑出现糖脂代谢异常及相关机制。AD患者早期脑内也有糖脂代谢的紊乱,且代谢紊乱进一步加重认知障碍。因此,ApoE导致大脑代谢紊乱,可能促进AD的发生发展。靶向ApoE4改善大脑代谢,可能是AD药物研发的新方向。     

Image-Feature Based Deep Learning Model for Plant Leaf Disease Detection

Currently, everyone is facing significant difficulties with food scarcity. There may be several causes for this, but food loss is a well-known issue. Specifically, crop losses bring on by plant and leaf diseases during farming operations. Plant disease is typically identified visually or through laboratory testing, which delays detection and reduces crop yields by the time it is finished. The wide use of smartphones along with recent advancements in computer vision has made it viable to diagnose any ailment by applying machine learning techniques. Smartphone-assisted disease diagnosis is now a reality. In this study, a multi-Support Vector Machine (SVM) model is used to detect four different diseases as well as healthy conditions of plant leaves. Using 13 feature vectors for each input, a total of 2400 leaves representing four distinct classes (four varieties) have been used to train and test the model. The experimental results give an average accuracy of 91.25% for diseased leaves detection and 99% accuracy for healthy leaves detection.     

Synthesis of Proposed Structure of Aaptoline A,a Marine Sponge-Derived 7,8-Dihydroxyquinoline,and Its Neuroprotective Properties in C. elegans

A concise and efficient synthesis of the proposed structure of aaptoline A, a 7,8-dihydroxyquinoline derived from a marine sponge, was accomplished in seven steps with a 52% overall yield. A key feature of the synthesis is the high-yielding Ag(I)-catalyzed cycloisomerization of the N-propargylaniline precursor to afford the quinoline carboxylate skeleton from acid-labile methyl aminobenzoate. However, the spectral data of the synthesized aaptoline A were not consistent with those of previous studies. The structure of the synthesized aaptoline A was confirmed by combined 2D NMR analysis. Additional studies on the bioactivity of the synthesized aaptoline A revealed that it has the ability to protect dopaminergic neurons against MPP⁺-induced neurotoxicity in C. elegans. In addition, impaired food-sensing ability and travel distance capability in C. elegans were significantly ameliorated by aaptoline A treatment, suggesting that aaptoline A can protect dopaminergic neurons both morphologically and functionally.