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Anja Kombrink, Hanna Rovenich, Xiaoqian Shi-Kunne, Eduardo Rojas-Padilla, Grardy C M van den Berg, Emmanouil Domazakis, Ronnie de Jonge, Dirk-Jan Valkenburg, Andrea Sánchez-Vallet, Michael F Seidl, Bart P H J Thomma
Chitin-binding LysM effectors contribute to virulence of various plant pathogenic fungi that are causal agents of foliar diseases. Here, we report on LysM effectors of the soil-borne fungal vascular wilt pathogen Verticillium dahliae. Comparative genomics revealed three core LysM effectors that are conserved in a collection of V. dahliae strains. Remarkably, and in contrast to the previously studied LysM effectors of other plant pathogens, no expression of core LysM effectors was monitored in planta in a taxonomically diverse panel of host plants...
December 2, 2016: Molecular Plant Pathology
Flávio Augusto Cardozo, Nadia Catalina Alfonso Vargas, Cristina Kraemer Zimpel, Adalberto Pessoa, Irma Nelly Gutierrez Rivera
We report here the draft genome sequence of Aeromonas caviae CH129, a marine-derived bacterium isolated from the coast of São Paulo state, Brazil. Genomic analysis revealed genes encoding enzymes involved in binding, transport, and chitin metabolism and different virulence-associated factors.
December 1, 2016: Genome Announcements
Takafumi Itoh, Takao Hibi, Fumiko Suzuki, Ikumi Sugimoto, Akihiro Fujiwara, Koji Inaka, Hiroaki Tanaka, Kazunori Ohta, Yutaka Fujii, Akira Taketo, Hisashi Kimoto
The Gram-positive bacterium Paenibacillus sp. str. FPU-7 effectively hydrolyzes chitin by using a number of chitinases. A unique chitinase with two catalytic domains, ChiW, is expressed on the cell surface of this bacterium and has high activity towards various chitins, even crystalline chitin. Here, the crystal structure of ChiW at 2.1 Å resolution is presented and describes how the enzyme degrades chitin on the bacterial cell surface. The crystal structure revealed a unique multi-modular architecture composed of six domains to function efficiently on the cell surface: a right-handed β-helix domain (carbohydrate-binding module family 54, CBM-54), a Gly-Ser-rich loop, 1st immunoglobulin-like (Ig-like) fold domain, 1st β/α-barrel catalytic domain (glycoside hydrolase family 18, GH-18), 2nd Ig-like fold domain and 2nd β/α-barrel catalytic domain (GH-18)...
2016: PloS One
Dithi Banerjee, Timothy C Umland, John C Panepinto
The use of amphotericin B (AmB) in conjunction with 5-fluorocytosine (5-FC) is known to be the optimal therapy for treating cryptococcosis, but the mechanism by which 5-FC synergizes with AmB is unknown. In this study, we generated a Cryptococcus neoformans ura1Δ mutant lacking dihydroorotate dehydrogenase (DHODH), which demonstrated temperature-sensitive growth due to a defect in cell integrity and sensitivity to cell wall-damaging agents. In addition, sensitivity to AmB was greatly increased. Inclusion of uracil or uridine in the medium did not suppress the cell wall or AmB phenotype, whereas complementation with the wild-type URA1 gene complemented the mutant phenotype...
November 2016: MSphere
Stefan Cord-Landwehr, Rebecca L J Melcher, Stephan Kolkenbrock, Bruno M Moerschbacher
To successfully survive in plants, endophytes need strategies to avoid being detected by the plant immune system, as the cell walls of endophytes contain easily detectible chitin. It is possible that endophytes "hide" this chitin from the plant immune system by modifying it, or oligomers derived from it, using chitin deacetylases (CDA). To explore this hypothesis, we identified and expressed a CDA from Pestalotiopsis sp. (PesCDA), an endophytic fungus, in E. coli and characterized this enzyme and its chitosan oligomer products...
November 30, 2016: Scientific Reports
Ezzeddin M A Hejjaji, Alan M Smith, Gordon A Morris
Chitosan (CS) is a natural cationic polymer obtained by the partial N-deacetylation of chitin. Chitosan microparticles can be prepared by cross-linking with tripolyphosphate (TPP) via the ionic interaction between positively charged amino groups (CS) and negatively charged counter ions (TPP). This can be controlled by the charge density of CS and TPP, which depend on the pH and ionic strength of the solution. The purpose of this study is to investigate the combined effects of three independent variables (pH, ionic strength and CS: TPP ratio) on three important physico-chemical properties (viscosity, zeta potential and particle size) during the preparation of microparticles...
November 25, 2016: International Journal of Biological Macromolecules
Yue-Cheng Lin, Hong-Peng Wang, Faryal Gohar, Muhammad Haseeb Ullah, Xiang Zhang, Dong-Fang Xie, Hui Fang, Jun Huang, Jun-Xing Yang
Chitosan was prepared by alkaline N-deacetylation of β-chitin from squid pens. Thiosemicarbazide group was introduced to chitosan via formaldehyde-derived linkages, and thiosemicarbazide chitosan (TSFCS) with different degrees of substitution (DS) was synthesized. The DS values of TSFCS calculated by elemental analysis were 0.19, 0.36 and 0.63. The structure of the TSFCS was confirmed by elemental analysis, FTIR, XRD, TGA and SEM. The adsorption capacity of Cu(II) ions by TSFCS showed good correlation with the DS and pH (pH range 2...
November 24, 2016: International Journal of Biological Macromolecules
Catherine Espinoza, Yan Liang, Gary Stacey
In nature, plants need to respond to multiple environmental stresses that require involvement and fine-tuning of different stress signaling pathways. Cross-tolerance in which plants pre-treated with chitin (a fungal microbe-associated molecular pattern) have improved salt tolerance was observed in Arabidopsis but is not well understood. Here, we show a unique link between chitin and salt signaling mediated by the chitin receptor CHITIN ELICITOR RECEPTOR KINASE 1 (CERK1). Transcriptome analysis revealed that salt stress-induced genes are highly correlated with chitin-induced genes, while this was not observed with other microbe-associated molecular patterns (MAMP) or with other abiotic stresses...
November 26, 2016: Plant Journal: for Cell and Molecular Biology
Suhair S Al-Nimry, Khouloud A Alkhamis, Kawthar Z Alzarieni
Chitin-metal silicates are multifunctional excipients used in tablets. Previously, a correlation between the surface acidity of chitin-calcium and chitin-magnesium silicate and the chemical decomposition of cefotaxime sodium was found but not with chitin-aluminum silicate. This lack of correlation could be due to the catalytic effect of silica alumina or the difference in surface area of the excipients. The objective of this study was to investigate the effect of the specific surface area of the excipient on the chemical decomposition of cefotaxime sodium in the solid state...
November 22, 2016: Journal of Pharmaceutical Sciences
Tengchao Li, Jie Chen, Xiaobin Fan, Weiwen Chen, Wenqing Zhang
BACKGROUND: Two RNA silencing pathways in insects are known to exist that are mediated by short interfering RNAs (siRNAs) and microRNAs (miRNAs), which have been hypothesized to be promising methods for insect pest control. However, a comparison between miRNA and siRNA in pest control is still unavailable, particularly in targeting chitin synthase gene A (CHSA). RESULTS: The dsRNA for Nilaparvata lugens CHSA (dsNlCHSA) and microR-2703 (miR-2703) mimic targeting NlCHSA delivered via feeding affected the development of nymphs, reduced their chitin content and led to lethal phenotypes...
November 25, 2016: Pest Management Science
Misa Ohno, Masahiro Kimura, Haruko Miyazaki, Kazuaki Okawa, Riho Onuki, Chiyuki Nemoto, Eri Tabata, Satoshi Wakita, Akinori Kashimura, Masayoshi Sakaguchi, Yasusato Sugahara, Nobuyuki Nukina, Peter O Bauer, Fumitaka Oyama
Chitinases are enzymes that hydrolyze chitin, a polymer of β-1, 4-linked N-acetyl-D-glucosamine (GlcNAc). Chitin has long been considered as a source of dietary fiber that is not digested in the mammalian digestive system. Here, we provide evidence that acidic mammalian chitinase (AMCase) can function as a major digestive enzyme that constitutively degrades chitin substrates and produces (GlcNAc)2 fragments in the mouse gastrointestinal environment. AMCase was resistant to endogenous pepsin C digestion and remained active in the mouse stomach extract at pH 2...
November 24, 2016: Scientific Reports
Isabelle R Gonçalves, Sophie Brouillet, Marie-Christine Soulié, Simonetta Gribaldo, Catherine Sirven, Noémie Charron, Martine Boccara, Mathias Choquer
BACKGROUND: Chitin, the second most abundant biopolymer on earth after cellulose, is found in probably all fungi, many animals (mainly invertebrates), several protists and a few algae, playing an essential role in the development of many of them. This polysaccharide is produced by type 2 glycosyltransferases, called chitin synthases (CHS). There are several contradictory classifications of CHS isoenzymes and, as regards their evolutionary history, their origin and diversity is still a matter of debate...
November 24, 2016: BMC Evolutionary Biology
Hui-Qiang Feng, Gui-Hua Li, Du Shun-Wen, Song Yang, Xue-Qian Li, Paul de Figueiredo, Qing-Ming Qin
Many phytopathogenic fungi use infection structures (IFSs, i.e., appressoria and infection cushions) to penetrate host cuticles. However, the conserved mechanisms that mediate initiation of IFS formation in divergent pathogens upon sensing the presence of host plants remain obscure. Here, we demonstrate that a conserved septin gene SEP4 plays crucial roles in this process. Disruption of SEP4 in the plant gray mold fungus Botrytis cinerea completely blocked IFS formation and abolished the virulence of ΔBcsep4 mutants on unwounded hosts...
November 23, 2016: Environmental Microbiology
Ji-Feng Shi, Li-Li Mu, Xu Chen, Wen-Chao Guo, Guo-Qing Li
Dietary introduction of bacterially expressed double-stranded RNA (dsRNA) has great potential for management of Leptinotarsa decemlineata. Identification of the most attractive candidate genes for RNA interference (RNAi) is the first step. In the present paper, three complete chitin synthase cDNA sequences (LdChSAa, LdChSAb and LdChSB) were cloned. LdChSAa and LdChSAb, two splicing variants of LdChSA gene, were highly expressed in ectodermally-derived epidermal cells forming epidermis, trachea, foregut and hindgut, whereas LdChSB was mainly transcribed in midgut cells...
2016: International Journal of Biological Sciences
Zailei Zhang, Ji Chul Jung, Ning Yan
Despite intensive research into support substrates for the dispersal of nanoparticles and their applications, there has been a lack of general methods to produce metal oxide hollow substrates supporting a wide range of metal and metal oxides. Herein, a synthetic protocol for the preparation of CuO hollow structure-supported MOx (M = Zn, Fe, Ni, Sn, Mn, Co, Ce, Mg, and Ag) and noble metals (Pt and Au) with the desired properties and shell structure, such as CuO/Fe2O3, CuO/ZnO, CuO/SnO2, CuO/MgO, CuO/NiO, CuO/Mn2O3, CuO/CoO, CuO/CeO2, CuO/Ag2O, CuO/Pt, CuO/Au hollow cubes, CuO/ZnO double-shell hollow cubes, CuO/SnO2 double-shell hollow octahedra, CuO/SnO2/Fe2O3 and CuO/Mn2O3/NiO double-shell hollow cubes, was developed based on controlled calcination and etching...
December 1, 2016: Nanoscale
Diana Pisa, Ruth Alonso, Alberto Rábano, Michael N Horst, Luis Carrasco
Recent findings provide evidence that fungal structures can be detected in brain tissue from Alzheimer's disease (AD) patients using rabbit polyclonal antibodies raised against whole fungal cells. In the present work, we have developed and tested specific antibodies that recognize the fungal proteins, enolase and β-tubulin, and an antibody that recognizes the fungal polysaccharide chitin. Consistent with our previous studies, a number of rounded yeast-like and hyphal structures were detected using these antibodies in brain sections from AD patients...
2016: Frontiers in Microbiology
Veronika Loiko, Johannes Wagener
Echinocandins target the fungal cell wall by inhibiting biosynthesis of the cell wall carbohydrate β-1,3-glucan. This antifungal drug class exhibits a paradoxical effect which is characterized by the resume of growth of otherwise susceptible strains at higher drug concentrations (approx.4-32 μg/ml). The nature of this phenomenon is still unknown. In this study, we analyzed the paradoxical effect of the echinocandin caspofungin on the pathogenic mold Aspergillus fumigatus Using a conditional fks1 mutant, we show that very high caspofungin concentrations exert an additional antifungal activity beside inhibition of the β-1,3-glucan synthase...
November 21, 2016: Antimicrobial Agents and Chemotherapy
Jason A Lee, Nicole Robbins, Jinglin L Xie, Troy Ketela, Leah E Cowen
Fungal biofilms are complex, structured communities that can form on surfaces such as catheters and other indwelling medical devices. Biofilms are of particular concern with Candida albicans, one of the leading opportunistic fungal pathogens of humans. C. albicans biofilms include yeast and filamentous cells that are surrounded by an extracellular matrix, and they are intrinsically resistant to antifungal drugs such that resolving biofilm infections often requires surgery to remove the contaminated device. C...
November 2016: PLoS Genetics
Odette González Macé, Katja Steinauer, Alexandre Jousset, Nico Eisenhauer, Stefan Scheu
Flooding frequency is predicted to increase during the next decades, calling for a better understanding of impacts on terrestrial ecosystems and for developing strategies to mitigate potential damage. Plant diversity is expected to buffer flooding effects by providing a broad range of species' responses. Here we report on the response of soil processes to a severe summer flood in 2013, which affected major parts of central Europe. We compared soil microbial respiration, biomass, nutrient limitation and enzyme activity in a grassland biodiversity experiment in Germany before flooding, one week and three months after the flood...
2016: PloS One
Yuuki Hayakawa, Daiki Kato, Katsumi Kamiya, Chieka Minakuchi, Ken Miura
The importance of the insect cuticle as a primary protective barrier against entomopathogens has long been noted. In the present study, we addressed this issue by utilizing an experimental infection system composed of the model beetle T. castaneum and two entomopathogenic fungal species, Beauveria bassiana and Metarhizium anisopliae. The pupae were relatively susceptible to these fungi by the natural route of infection, with some refractoriness developed with age, while the adults exhibited much higher refractoriness...
November 17, 2016: Journal of Invertebrate Pathology
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