Transformation: a tool for studying fungal pathogens of plants

Plant diseases caused by plant pathogenic fungi continuously threaten the sustainability of global crop production. An effective way to study the disease-causing mechanisms of these organisms is to disrupt their genes, in both a targeted and random manner, so as to isolate mutants exhibiting altered virulence. Although a number of techniques have been employed for such an analysis, those based on transformation are by far the most commonly used. In filamentous fungi, the introduction of DNA by transformation typically results in either the heterologous (illegitimate) integration or the homologous integration of the transforming DNA into the target genome. Homologous integration permits a targeted gene disruption by replacing the wild-type allele on the genome with a mutant allele on transforming DNA. This process has been widely used to determine the role of newly isolated fungal genes in pathogenicity. The heterologous integration of transforming DNA causes a random process of gene disruption (insertional mutagenesis) and has led to the isolation of many fungal mutants defective in pathogenicity. A big advantage of insertional mutagenesis over the more traditional chemical or radiation mutagenesis procedures is that the mutated gene is tagged by transforming DNA and can subsequently be cloned using the transforming DNA. The application of various transformation-based techniques for fungal gene manipulation and how they have increased our understanding and appreciation of some of the most serious plant pathogenic fungi are discussed. Received 9 May 2001; received after revision 2 July 2001; accepted 3 July 2001     

Role of fungal statling growth products in inter-specific competition among phylloplane fungi

Summary The effect of fungal staling growth products on leaf-inhabiting microfungi, with special reference to a leaf spot pathogenPestalotiopsis funerea Desm. ofEucalyptus globulus Labill. was studied. Results depict that antibiotics produced by competing microfungi caused the phenomenon of mycostasis on the leaf surfaces.Acknowledgments. I would like to express my thanks to Professor R.S. Dwivedi for his encouragement and to CSIR (Indian Govt.) for financial assistance.     

俄罗斯海洋政策和战略

文章综述了俄罗斯近年来的海洋政策、管理体制、发展战略和对世界海洋资源分配和开发立场以及维权措施.     

How plants recognize pathogens and defend themselves

Plants have an innate immunity system to defend themselves against pathogens. With the primary immune system, plants recognize microbe-associated molecular patterns (MAMPs) of potential pathogens through pattern recognition receptors (PRRs) that mediate a basal defense response. Plant pathogens suppress this basal defense response by means of effectors that enable them to cause disease. With the secondary immune system, plants have gained the ability to recognize effector-induced perturbations of host targets through resistance proteins (RPs) that mediate a strong local defense response that stops pathogen growth. Both primary and secondary immune responses in plants depend on germ line-encoded PRRs and RPs. During induction of local immune responses, systemic immune responses also become activated, which predispose plants to become more resistant to subsequent pathogen attacks. This review gives an update on recent findings that have enhanced our understanding of plant innate immunity and the arms race between plants and their pathogens. Received 24 June 2007; received after revision 18 July 2007; accepted 15 August 2007     

Chitotriosidase and gene therapy for fungal infections

Chitotriosidase secreted by activated human macrophages has been implicated in the defence against chitin-bearing pathogens. The antifungal properties of human chitotriosidase were investigated here following retroviral vector-mediated gene transfer of the open reading frame of the chitotriosidase gene into Chinese hamster ovary cells. A chitinase assay confirmed that the engineered cells secreted recombinant chitotriosidase constitutively. Two dimensional gel electrophoresis and western blotting indicated that the recombinant protein is the major, chitin-binding, fifty kilodalton isoform. Culture medium conditioned by the transduced cells inhibited growth of isolates of Aspergillus niger, Candida albicans and Cryptococcus neoformans. Furthermore, longevity was significantly increased in a mouse model of cryptococcosis when cells transduced with the chitotriosidase gene and encapsulated in alginate microspheres were implanted subcutaneously in the animals. Engraftment of microcapsules containing cells transduced with the chitotriosidase gene has the potential to combat infections caused by chitinous pathogens through the prolonged delivery of recombinant chitotriosidase. Received 29 November 2008; received after revision 11 January 2009; accepted 13 January 2009     

海洋生物地球化学的产生与发展

对全球环境问题如全球气候变化、全球生态环境变化等的关注导致了海洋生物地球化学的飞速发展,使海洋生物地球化学成为了全球变化研究的核心,本文阐述了海洋生物地球化学的产生与发展及我们实验室近年来这方面研究的主要结果。     

Modulation of connexin signaling by bacterial pathogens and their toxins

Inherent to their pivotal tasks in the maintenance of cellular homeostasis, gap junctions, connexin hemichannels, and pannexin hemichannels are frequently involved in the dysregulation of this critical balance. The present paper specifically focuses on their roles in bacterial infection and disease. In particular, the reported biological outcome of clinically important bacteria including Escherichia coli, Shigella flexneri, Yersinia enterocolitica, Helicobacter pylori, Bordetella pertussis, Aggregatibacter actinomycetemcomitans, Pseudomonas aeruginosa, Citrobacter rodentium, Clostridium species, Streptococcus pneumoniae, and Staphylococcus aureus and their toxic products on connexin- and pannexin-related signaling in host cells is reviewed. Particular attention is paid to the underlying molecular mechanisms of these effects as well as to the actual biological relevance of these findings.     

世界海洋环境中的塑料污染现状分析及治理建议

塑料碎片在环境中广泛存在,目前已成为海洋污染的重要来源,是当今海洋环境中不可忽视的新型污染物。本文对近几年国际上有关海洋塑料污染的研究进行了梳理,综述了塑料碎片在世界海洋环境中的含量分布及对海洋生态环境的危害,分析了国际上为应对海洋塑料污染采取的相关行动举措,同时对加强海洋塑料污染的防治提出了建议。     

中国海洋科技研究动态与前瞻

海洋科技是人类利用海洋的产物,又是人类推动海洋经济社会与海洋环境可持续发展的主要驱动力。中国学者围绕海洋科技战略、海洋科技产业、海洋科技创新能力与绩效、海洋科技成果转化、海洋科技体制以及重点海洋基础学科与海洋工程技术学科的相关领域进行了卓有成效的探索。梳理文献发现中国海洋科技研究有4个主要特点:1海洋科技战略研究侧重战略目标及其实现路线、重点海洋产业的技术战略、海洋科技成果的产业化战略等;2海洋科技产业研究局限在产业集聚影响因素与集聚区建设模式、效益评估与区域合作路径;3海洋科技创新能力研究集中在资源配置、省份与市的海洋科技能力横向或纵向比较、共性技术研发模式及科技效率问题;4海洋科技成果转化研究关注不同主体及其转化过程实现机制,而海洋科技管理研究则关注宏观体制变革;海洋科研项目的立项、评审与经费管理;海洋科技主体与载体建设等。最后立足于海洋科技国际发展趋势,指出未来研究前沿领域。     

Preliminary report on toxigenic fungal isolates ofAspergillus niger in market foods and foodstuffs

Summary 14 out of 22 fungal isolates ofA. niger from market foods and foodstuffs were toxigenic to weanling rats. Approximately 2/3 of these cultures were highly toxigenic. Histopathologic changes were observed mostly in kidney with necrosis of the tubular epithelium and to a less extent in liver with centrolobular necorsis of the hepatic cells.Acknowledgment. We wish to thank Miss Wilai Limpasuk for her excellent secretarial assistance.     

The STING pathway and regulation of innate immune signaling in response to DNA pathogens

The innate immune system has evolved a variety of sensing mechanisms to detect and counter microbial invasion. These include the Toll-like receptor (TLR), cytoplasmic, nucleotide binding oligomerization domain (NOD)-like receptor and RIG-I-like helicase (RLH) pathways. However, how the cell detects pathogen-associated DNA to trigger host defense, including the production of interferon, remains to be fully clarified. Understanding these processes could have profound implications into how we understand and treat a variety of microbial-related disease, including viral-associated cancers, as well as autoimmune disorders. Recently, an endoplasmic reticulum-associated molecule referred to as STING (for stimulator of interferon genes) was isolated and shown to be critical for regulating the production of IFN in response to cytoplasmic DNA. Here, we review recent discoveries relating to the detection of foreign DNA, including the importance of the STING and inflammasome pathways and the triggering of innate signaling processes.     

Hyaluronan synthases: fascinating glycosyltransferases from vertebrates, bacterial pathogens, and algal viruses

Hyaluronan (or hyaluronic acid or hyaluronate; HA) is a polysaccharide found in the extracellular matrix of vertebrate tissues and in the surface coating of certain Streptococcus and Pasteurella bacterial pathogens. At least one algal virus directs its host to produce HA on the cell surface early in infection. HA synthases (HASs) are the enzymes that polymerize HA using uridine diphospho-sugar precursors. In all known cases, HA is secreted out of the cell; therefore, HASs are normally found in the outer membranes of the organism. In the last 6 years, the HASs have been molecularly cloned from all the above sources. They were the first class of glycosyltransferases identified in which a single polypeptide species catalyzes the transfer of two different monosaccharides; this finding is in contrast to the usual 'single enzyme, single sugar' dogma of glycobiology. There appear to be two distinct classes of HASs based on differences in amino acid sequence, topology in the membrane, and reaction mechanism. This review discusses the current state of knowledge surrounding the molecular details of HA biosynthesis and summarizes the possible evolutionary history of the HASs.     

Photodecomposition of orellanine and orellinine,the fungal toxins ofCortinarius orellanus Fries andCortinarius speciossimus

Summary The photosensitivity of orellanine, the main toxin ofCortinarius orellanus Fries mushrooms, and its transformation to orelline via orellinine is discussed. All three substances were found in methanolic extracts ofCortinarius orellanus andCortinarius speciossimus mushrooms. The problem of homogeneity of orellanine is also discussed.Acknowledgment. The authors wish to express their gratitude to Prof. Dr W. Steglich from the Institut für Organische Chemie und Biochemie der Universität Bonn (Federal Republic of Germany) for having provided them with a sample of dried material ofC. speciossisimus.     

Pathogenesis of skin ulcers: lessons from the Mycobacterium ulcerans and Leishmania spp. pathogens

Skin ulcers are most commonly due to circulatory or metabolic disorders and are a major public health concern. In developed countries, chronic wounds affect more than 1 % of the population and their incidence is expected to follow those observed for diabetes and obesity. In tropical and subtropical countries, an additional issue is the occurrence of ulcers of infectious origins with diverse etiologies. While the severity of cutaneous Leishmaniasis correlates with protective immune responses, Buruli ulcers caused by Mycobacterium ulcerans develop in the absence of major inflammation. Based on these two examples, this review aims to demonstrate how studies on microorganism-provoked wounds can provide insight into the molecular mechanisms controlling skin integrity. We highlight the potential interest of a mouse model of non-inflammatory skin ulceration caused by intradermal injection of mycolactone, an original lipid toxin with ulcerative and immunosuppressive properties produced by M. ulcerans.     

海洋活性肽研究的回顾与展望

海洋环境资源丰富,物种多样,是活性肽开发与研究的巨大宝库。本文分析了活性肽丰富的海洋来源及生物功用,并且对活性肽的自然来源途径和人工合成来源途径进行了论述,包括活性肽的分离、纯化、合成、筛选等方面,并强调了海洋活性肽在食品工业、医药学、畜牧业、水产养殖业、尤其是在环境保护中的应用现状与潜力,还从多角度、多层面对海洋活性肽的研究作出展望．