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61.
James Skelton Michelle A. Jusino Paige S. Carlson Katherine Smith Mark T. Banik Daniel L. Lindner Jonathan M. Palmer Jiri Hulcr 《Molecular ecology》2019,28(22):4971-4986
A prevailing paradigm in forest ecology is that wood‐boring beetles facilitate wood decay and carbon cycling, but empirical tests have yielded mixed results. We experimentally determined the effects of wood borers on fungal community assembly and wood decay within pine trunks in the southeastern United States. Pine trunks were made either beetle‐accessible or inaccessible. Fungal communities were compared using culturing and high‐throughput amplicon sequencing (HTAS) of DNA and RNA. Prior to beetle infestation, living pines had diverse fungal endophyte communities. Endophytes were displaced by beetle‐associated fungi in beetle‐accessible trees, whereas some endophytes persisted as saprotrophs in beetle‐excluded trees. Beetles increased fungal diversity several fold. Over forty taxa of Ascomycota were significantly associated with beetles, but beetles were not consistently associated with any known wood‐decaying fungi. Instead, increasing ambrosia beetle infestations caused reduced decay, consistent with previous in vitro experiments that showed beetle‐associated fungi reduce decay rates by competing with decay fungi. No effect of bark‐inhabiting beetles on decay was detected. Platypodines carried significantly more fungal taxa than scolytines. Molecular results were validated by synthetic and biological mock communities and were consistent across methodologies. RNA sequencing confirmed that beetle‐associated fungi were biologically active in the wood. Metabarcode sequencing of the LSU/28S marker recovered important fungal symbionts that were missed by ITS2, though community‐level effects were similar between markers. In contrast to the current paradigm, our results indicate ambrosia beetles introduce diverse fungal communities that do not extensively decay wood, but instead reduce decay rates by competing with wood decay fungi. 相似文献
62.
Role of fungi in freshwater ecosystems 总被引:7,自引:0,他引:7
Michelle K.M. Wong Teik-Khiang Goh I. John Hodgkiss Kevin D. Hyde V. Mala Ranghoo Clement K.M. Tsui Wai-Hong Ho Wilson S.W. Wong Tsz-Kit Yuen 《Biodiversity and Conservation》1998,7(9):1187-1206
There are more than 600 species of freshwater fungi with a greater number known from temperate, as compared to tropical, regions. Three main groups can be considered which include Ingoldian fungi, aquatic ascomycetes and non-Ingoldian hyphomycetes, chytrids and, oomycetes. The fungi occurring in lentic habitats mostly differ from those occurring in lotic habitats. Although there is no comprehensive work dealing with the biogeography of all groups of freshwater fungi, their distribution probably follows that of Ingoldian fungi, which are either cosmopolitan, restricted to pantemperate or pantropical regions, or in a few cases, have a restricted distribution. Freshwater fungi are thought to have evolved from terrestrial ancestors. Many species are clearly adapted to life in freshwater as their propagules have specialised aquatic dispersal abilities. Freshwater fungi are involved in the decay of wood and leafy material and also cause diseases of plants and animals. These areas are briefly reviewed. Gaps in our knowledge of freshwater fungi are discussed and areas in need of research are suggested. 相似文献
63.
Jaing C Gardner S McLoughlin K Mulakken N Alegria-Hartman M Banda P Williams P Gu P Wagner M Manohar C Slezak T 《PloS one》2008,3(5):e2163
Emerging known and unknown pathogens create profound threats to public health. Platforms for rapid detection and characterization of microbial agents are critically needed to prevent and respond to disease outbreaks. Available detection technologies cannot provide broad functional information about known or novel organisms. As a step toward developing such a system, we have produced and tested a series of high-density functional gene arrays to detect elements of virulence and antibiotic resistance mechanisms. Our first generation array targets genes from Escherichia coli strains K12 and CFT073, Enterococcus faecalis and Staphylococcus aureus. We determined optimal probe design parameters for gene family detection and discrimination. When tested with organisms at varying phylogenetic distances from the four target strains, the array detected orthologs for the majority of targeted gene families present in bacteria belonging to the same taxonomic family. In combination with whole-genome amplification, the array detects femtogram concentrations of purified DNA, either spiked in to an aerosol sample background, or in combinations from one or more of the four target organisms. This is the first report of a high density NimbleGen microarray system targeting microbial antibiotic resistance and virulence mechanisms. By targeting virulence gene families as well as genes unique to specific biothreat agents, these arrays will provide important data about the pathogenic potential and drug resistance profiles of unknown organisms in environmental samples. 相似文献
64.
Bitinaite J Rubino M Varma KH Schildkraut I Vaisvila R Vaiskunaite R 《Nucleic acids research》2007,35(6):1992-2002
Here we report a PCR-based DNA engineering technique for seamless assembly of recombinant molecules from multiple components. We create cloning vector and target molecules flanked with compatible single-stranded (ss) extensions. The vector contains a cassette with two inversely oriented nicking endonuclease sites separated by restriction endonuclease site(s). The spacer sequences between the nicking and restriction sites are tailored to create ss extensions of custom sequence. The vector is then linearized by digestion with nicking and restriction endonucleases. To generate target molecules, a single deoxyuridine (dU) residue is placed 6–10nt away from the 5′-end of each PCR primer. 5′ of dU the primer sequence is compatible either with an ss extension on the vector or with the ss extension of the next-in-line PCR product. After amplification, the dU is excised from the PCR products with the USER enzyme leaving PCR products flanked by 3′ ss extensions. When mixed together, the linearized vector and PCR products directionally assemble into a recombinant molecule through complementary ss extensions. By varying the design of the PCR primers, the protocol is easily adapted to perform one or more simultaneous DNA manipulations such as directional cloning, site-specific mutagenesis, sequence insertion or deletion and sequence assembly. 相似文献
65.
Ben Khalaf N De Muylder G Ratnam J Kean-Hooi Ang K Arkin M McKerrow J Chenik M 《Journal of biomolecular screening》2011,16(5):545-551
The use of a high-throughput technique to perform a pilot screen for Leishmania major protein disulfide isomerase (LmPDI) inhibitors identification is reported. In eukaryotic cells, protein disulfide isomerase (PDI) plays a crucial role in protein folding by catalyzing the rearrangement of disulfide bonds in substrate proteins following their synthesis. LmPDI displays similar domain structure organization and functional properties to other PDI family members and is involved in Leishmania virulence. The authors used a method based on the enzyme-catalyzed reduction of insulin in the presence of dithiothreitol. The screen of a small library of 1920 compounds was performed in a 384-well format and led to the identification of 27 compounds with inhibitory activity against LmPDI. The authors further tested the cytotoxicity of these compounds using Jurkat cells as well as their effect on Leishmania donovani amastigotes using high-content analysis. Results show hexachlorophene and a mixture of theaflavin monogallates inhibit Leishmania multiplication in infected macrophages derived from THP-1 cells, although the inhibitory effect on LmPDI enzymatic activity does not necessarily correlate with the antileishmanial activity. 相似文献
66.
Critical but distinct roles for the pleckstrin homology and cysteine-rich domains as positive modulators of Vav2 signaling and transformation 下载免费PDF全文
Vav2, like all Dbl family proteins, possesses tandem Dbl homology (DH) and pleckstrin homology (PH) domains and functions as a guanine nucleotide exchange factor for Rho family GTPases. Whereas the PH domain is a critical positive regulator of DH domain function for a majority of Dbl family proteins, the PH domains of the related Vav and Vav3 proteins are dispensable for DH domain activity. Instead, Vav proteins contain a cysteine-rich domain (CRD) critical for DH domain function. We evaluated the contribution of the PH domain and the CRD to Vav2 guanine nucleotide exchange, signaling, and transforming activity. Unexpectedly, we found that mutations of the PH domain impaired Vav2 signaling, transforming activity, and membrane association. However, these mutations do not influence exchange activity on Rac and only slightly affect exchange on RhoA and Cdc42. We also found that the CRD was critical for the exchange activity in vitro and contributed to Vav2 membrane localization. Finally, we found that phosphoinositol 3-kinase activation synergistically enhanced Vav2 transforming and signaling activity by stimulating exchange activity but not membrane association. In conclusion, the PH domain and CRD are mechanistically distinct, positive modulators of Vav2 DH domain function in vivo. 相似文献
67.
68.
Katy Jeannot Laure Diancourt Sophie Vaux Michelle Thouverez Amandina Ribeiro Bruno Coignard Patrice Courvalin Sylvain Brisse 《PloS one》2014,9(12)
Carbapenem-resistant Acinetobacter baumannii have emerged globally. The objective of this study was to investigate the epidemiology, clonal diversity and resistance mechanisms of imipenem non-susceptible A. baumannii isolates in France. Between December 2010 and August 2011, 132 notifications were collected, including 37 outbreaks corresponding to 242 cases (2 to 55 per cluster). Multilocus sequence typing, pulsed-field gel electrophoresis (PFGE) and characterisation of carbapenemase-encoding genes were performed on 110 non-repetitive isolates. Gene bla
OXA-23 was the most frequently detected (82%), followed by bla
OXA-24 (11%) and bla
OXA-58 (7%). Eleven sequence types (ST) were distinguished, among which sequence types ST1, ST2 (64%), ST20, ST25, ST85 and ST107. Isolates from epidemiological clusters had the same ST and resistance genes, indicating probable transmission within centres. In contrast, PFGE types of isolates differed among centres, arguing against transmission among centers. This study provides the first epidemiological snapshot of the population of A. baumannii with reduced susceptibility to carbapenems from France, and further underlines the predominance of international clones. 相似文献
69.
70.
The TEL-Syk fusion protein was isolated from a patient with myelodysplasia with megakaryocyte blasts. Expression of TEL-Syk transforms interleukin-3 (IL-3)-dependent Ba/F3 cells in vitro by deregulating STAT5-mediated signal transduction pathways. In vivo, TEL-Syk expression in pre-B cells blocks B cell differentiation, leading to lymphoid leukemia. Here, we demonstrate that TEL-Syk introduced into fetal liver hematopoietic cells, which are then adoptively transferred into lethally irradiated recipients, leads to an aggressive myelodysplasia with myelofibrosis that is lethal in mice by 60–75 days. Expression of TEL-Syk induces a short-lived myeloexpansion that is rapidly followed by bone marrow failure and extreme splenic/hepatic fibrosis accompanied by extensive apoptosis. The disease is dependent on Syk kinase activity. Analysis of serum from TEL-Syk mice reveals an inflammatory cytokine signature reminiscent of that found in the sera from patients and mouse models of myeloproliferative neoplasms. TEL-Syk expressing cells showed constitutive STAT5 phosphorylation, which was resistant to JAK inhibition, consistent with deregulated cytokine signaling. These data indicate that expression of TEL-Syk in fetal liver hematopoietic cells results in JAK-independent STAT5 phosphorylation ultimately leading to a uniquely aggressive and lethal form of myelofibrosis. 相似文献