Metabolic priming by a secreted fungal effector

Maize smut caused by the fungus Ustilago maydis is a widespread disease characterized by the development of large plant tumours. U. maydis is a biotrophic pathogen that requires living plant tissue for its development and establishes an intimate interaction zone between fungal hyphae and the plant plasma membrane. U. maydis actively suppresses plant defence responses by secreted protein effectors. Its effector repertoire comprises at least 386 genes mostly encoding proteins of unknown function and expressed exclusively during the biotrophic stage. The U. maydis secretome also contains about 150 proteins with probable roles in fungal nutrition, fungal cell wall modification and host penetration as well as proteins unlikely to act in the fungal-host interface like a chorismate mutase. Chorismate mutases are key enzymes of the shikimate pathway and catalyse the conversion of chorismate to prephenate, the precursor for tyrosine and phenylalanine synthesis. Root-knot nematodes inject a secreted chorismate mutase into plant cells likely to affect development. Here we show that the chorismate mutase Cmu1 secreted by U. maydis is a virulence factor. The enzyme is taken up by plant cells, can spread to neighbouring cells and changes the metabolic status of these cells through metabolic priming. Secreted chorismate mutases are found in many plant-associated microbes and might serve as general tools for host manipulation.     

云南省个体、私营企业多层次抽样调查方案设计

为适应云南省经济体制的发现,提高应用抽样调查技术的水平,在考虑云南省个体或私营企业有关调查数据特点的基础上,设计了具有针对性的自然分层相接合的分层二阶抽样方案,以满足省和地区两组政府的需求。     

模糊化拟阵的最新进展

本文拟对模糊化拟阵理论做一个简短的介绍和评述,试图使读者了解模糊化拟阵理论的最新研究成果.     

一类矩阵方程的正交对称问题

针对约束矩阵方程问题,提出了一类矩阵方程的正交对称约束问题.通过研究正交对称矩阵与对称矩阵的关系,应用矩阵的标准相关分解(CCD)原理,获得了矩阵方程正交对称约束问题存在解的充要条件,以及该问题的通解表达式,并导出了与已知矩阵最佳逼近的正交对称解,也获得了方程相应的最小范数解.     

A point mutation in PTPRC is associated with the development of multiple sclerosis

Multiple sclerosis (MS) is the most common demyelinating disease of the central nervous system. It is widely accepted that a dysregulated immune response against brain resident antigens is central to its yet unknown pathogenesis. Although there is evidence that the development of MS has a genetic component, specific genetic factors are largely unknown. Here we investigated the role of a point mutation in the gene (PTPRC) encoding protein-tyrosine phosphatase, receptor-type C (also known as CD45) in the heterozygous state in the development of MS. The nucleotide transition in exon 4 of the gene locus interferes with mRNA splicing and results in altered expression of CD45 isoforms on immune cells. In three of four independent case-control studies, we demonstrated an association of the mutation with MS. We found the PTPRC mutation to be linked to and associated with the disease in three MS nuclear families. In one additional family, we found the same variant CD45 phenotype, with an as-yet-unknown origin, among the members affected with MS. Our findings suggest an association of the mutation in PTPRC with the development of MS in some families.     

改进的线性判别回归分类人脸识别算法

对线性回归分类算法进行了改进。考虑了线性回归分类算法中没有考虑的类间信息,通过选择类模式的投影方向判别不同类的模式,不同类的模式互相远离,相同类的模式尽可能靠近来估计投影矩阵;再利用投影矩阵将训练图像及测试图像投影到各类的特征子空间;最后,计算出测试图像与训练图像间的距离,利用K-近邻分类器完成人脸的识别。在FERET人脸数据库上进行实验验证。实验结果表明,相比其他回归分类算法,本算法取得了更好的识别效果。     

胺法烟气脱硫最新进展

胺法烟气脱硫技术是一种再生型分离技术.该技术主要的优势是:脱硫副产物综合利用价值高,并且不产生二次污染.对胺法烟气脱硫技术进行了评述,并对其发展趋势进行展望.     

丸尺蛾属(尺蛾科,灰尺蛾亚科)一中国新纪录种

记述采自四川乐山市的丸尺蛾属一中国新纪录种——Plutodes unidentata Holloway,1976.对其外部形态和生殖器进行了简要描述,给出其特征图.研究标本保存于西华师范大学昆虫标本馆.     

关于将脊椎动物形态解剖与分类学实验合并的思考与探索

动物形态解剖特征是分类的重要依据,与动物的进化和生态适应密不可分.但现有的动物学实验教材却将脊椎动物各纲的形态解剖与分类设置为不同的实验,这样就造成了形态解剖与分类学实验在时间、材料和内容上的脱节,影响学习效果.笔者建议在今后的实验教材编制、实验大纲设置和实验操作过程中,将这两类分别独立开设的实验合并为一个大实验.在学生系统学完一章的理论知识后,通过这一综合性实验,使学生能将动物的结构与分类鉴别特征及其生态功能的适应性有机地结合,以增强学习内容之间的内在联系,减少资源浪费,提高学生学习的兴趣和效率.