59 research outputs found

    Transcriptome Analysis of the Oriental Fruit Fly (Bactrocera dorsalis)

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    The oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most economically important pests in the world, causing serious damage to fruit production. However, lack of genetic information on this organism is an obstacle to understanding the mechanisms behind its development and its ability to resist insecticides. Analysis of the B. dorsalis transcriptome and its expression profile data is essential to extending the genetic information resources on this species, providing a shortcut that will support studies on B. dorsalis.We performed de novo assembly of a transcriptome using short read sequencing technology (Illumina). The results generated 484,628 contigs, 70,640 scaffolds, and 49,804 unigenes. Of those unigenes, 27,455 (55.13%) matched known proteins in the NCBI database, as determined by BLAST search. Clusters of orthologous groups (COG), gene orthology (GO), and the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations were performed to better understand the functions of these unigenes. Genes related to insecticide resistance were analyzed in additional detail. Digital gene expression (DGE) libraries showed differences in gene expression profiles at different developmental stages (eggs, third-instar larvae, pupae, and adults). To confirm the DGE results, the expression profiles of six randomly selected genes were analyzed.This transcriptome greatly improves our genetic understanding of B. dorsalis and makes a huge number of gene sequences available for further study, including both genes of known importance and genes of unknown function. The DGE data provide comprehensive insight into gene expression profiles at different developmental stages. This facilitates the study of the role of each gene in the developmental process and in insecticide resistance

    Functional Analysis of the Kinome of the Wheat Scab Fungus Fusarium graminearum

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    As in other eukaryotes, protein kinases play major regulatory roles in filamentous fungi. Although the genomes of many plant pathogenic fungi have been sequenced, systematic characterization of their kinomes has not been reported. The wheat scab fungus Fusarium graminearum has 116 protein kinases (PK) genes. Although twenty of them appeared to be essential, we generated deletion mutants for the other 96 PK genes, including 12 orthologs of essential genes in yeast. All of the PK mutants were assayed for changes in 17 phenotypes, including growth, conidiation, pathogenesis, stress responses, and sexual reproduction. Overall, deletion of 64 PK genes resulted in at least one of the phenotypes examined, including three mutants blocked in conidiation and five mutants with increased tolerance to hyperosmotic stress. In total, 42 PK mutants were significantly reduced in virulence or non-pathogenic, including mutants deleted of key components of the cAMP signaling and three MAPK pathways. A number of these PK genes, including Fg03146 and Fg04770 that are unique to filamentous fungi, are dispensable for hyphal growth and likely encode novel fungal virulence factors. Ascospores play a critical role in the initiation of wheat scab. Twenty-six PK mutants were blocked in perithecia formation or aborted in ascosporogenesis. Additional 19 mutants were defective in ascospore release or morphology. Interestingly, F. graminearum contains two aurora kinase genes with distinct functions, which has not been reported in fungi. In addition, we used the interlog approach to predict the PK-PK and PK-protein interaction networks of F. graminearum. Several predicted interactions were verified with yeast two-hybrid or co-immunoprecipitation assays. To our knowledge, this is the first functional characterization of the kinome in plant pathogenic fungi. Protein kinase genes important for various aspects of growth, developmental, and infection processes in F. graminearum were identified in this study

    Comparison of low temperature adaptation ability in three native and two hybrid strains of the rotifer Brachionus plicatilis species complex

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    The low temperature adaptation ability of five selected strains of the Brachionus plicatilis species complex, i.e., three native strains [ Japanese (NH1L), Australian, German] and two hybrid strains [♀NH1L and ♂Australian (N × A) and ♀NH1L and ♂German (N × G),was investigated in terms of life history traits, reproductive characteristics, and mobility under different thermal conditions (12 and 25 °C). The life history traits of these five strains included a longer lifespan, reproduction period and generation times at 12 °C than at 25 °C, combined with reduced lifetime egg and offspring production. At 12 °C, the intrinsic rate of natural increase was higher in NH1L and N × A strains. Reproductive characteristics determined at 12 °C by batch culture showed active population growth for NH1L and N × G strains, while no resting egg production was observed in all of the strains tested. The ratio of swimming rotifers at 12 °C was monitored every hour for 6 h (short term) and every day for 10 days (long term). In the short-term study there was a 81% ratio of swimming rotifers of the NH1L strain, while other strains exhibited low swimming ratios (75% swimming ratio from the initial day of the study. These results suggest that outcrossing of rotifer strains is useful to obtain live food resources for the larviculture of cold water fish

    金属氧化物纳米材料的设计与合成策略

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    Synthesis and characterization of In<inf>2</inf>O<inf>3</inf>/SnO <inf>2</inf> hetero-junction beaded nanowires

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    Hetero-junction beaded nanowires were synthesized via a simple thermal vapor deposition method. These nanowires were characterized with XRD, Raman, SEM, TEM, HRTEM, SAED and PL spectroscopy. Many single-crystal In 2O3 beads epitaxially grown along the axis of the single-crystal core SnO2 nanowires form the beaded nanowires. The In2O3 beads have definite orientations along the [2 0 0] direction of the core SnO2 nanowires and show regular rhombohedral morphology. A possible growth mechanism for the beaded nanowires is proposed. © 2005 Published by Elsevier B.V

    Synthesis, structure, and photoluminescence of Zn<inf>2</inf>SnO <inf>4</inf> single-crystal nanobelts and nanorings

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    A large quantity of single-crystal Zn2SnO4 (ZTO) nanobelts is synthesized by using a thermal evaporation method. The lengths of the nanobelts are up to several hundreds of micrometers, and the average width and thickness are about 400 and 30 nm, respectively. Some ring-like nanobelts, called nanorings here, are also observed. The nanobelts are characterized in detail with scanning electron microscope, X-ray powder diffraction, transmission electron microscope, high-resolution transmission electron microscope and selected area electron diffraction. Possible growth mechanisms for the ZTO nanobelts and nanorings are proposed. In addition, the photoluminescence spectrum (PL) of the nanobelts at room temperature shows a stable broad blue-green emission around the 400-600 nm wavelengths with a maximum center at 490 nm. The strong PL emission of the nanobelts may find potential applications in nano-scale optoelectronic devices. © 2004 Elsevier Ltd. All rights reserved

    Silver nanowires with five-fold symmetric cross-section

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    Uniform silver (Ag) nanowires with an average length of 6 μm and diameter of 70 nm have been synthesized via PVP-assisted (polyvinylpyrrolidone, PVP-K30) polyol reduction. The structure of thus-obtained Ag nanowires has been investigated thoroughly through scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Combined with the previous results, it is concluded that the Ag nanowires possess five-fold twinned crystal structure with [1 1 0] growth direction, bounded by five [1 0 0] planes and capped by ten [1 1 1] planes. The SAED of the pentagonal cross-section gives direct evidence of the five-fold symmetry of the Ag nanowires. The high-resolution TEM image clearly shows the five twinning boundaries with various defects. UV-visible absorption spectra, which are related to the well-defined structure of the Ag nanowires, exhibit unique transversal modes of the Ag nanowries. IR spectra of the Ag nanowires, compared with the pure PVP, indicate that the Ag atoms on the surface of the Ag nanowires are coordinated with oxygen atoms in the carbonyl group of the PVP. It has been proposed that the PVP main chain might lie on the surface of the Ag nanowires with the pyrrolidone ring tilted on them. © 2004 Elsevier B.V. All rights reserved
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