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Sample records for plant short silencing

  1. RNA silencing movement in plants

    Institute of Scientific and Technical Information of China (English)

    Glykeria Mermigka; Frederic Verret; Kriton Kalantidis

    2016-01-01

    Multicellular organisms, like higher plants, need to coordinate their growth and development and to cope with environmental cues. To achieve this, various signal molecules are transported between neighboring cells and distant organs to control the fate of the recipient cells and organs. RNA silencing produces cell non-autonomous signal molecules that can move over short or long distances leading to the sequence specific silencing of a target gene in a well defined area of cells or throughout the entire plant, respectively. The nature of these signal molecules, the route of silencing spread, and the genes involved in their production, movement and reception are discussed in this review. Additionally, a short section on features of silencing spread in animal models is presented at the end of this review.

  2. Epigenetic silencing in transgenic plants

    Directory of Open Access Journals (Sweden)

    Sarma eRajeev Kumar

    2015-09-01

    Full Text Available Epigenetic silencing is a natural phenomenon in which the expression of gene is regulated through modifications of DNA, RNA or histone proteins. It is a mechanism for defending host genomes against the effects of transposable element, viral infection and acts as a modulator of expression of duplicated gene family members and as a silencer of transgenes. A major breakthrough in understanding the mechanism of epigenetic silencing was discovery of silencing in transgenic tobacco plants due to interaction between two homologous promoters. The molecular mechanism of epigenetic mechanism is highly complicated and it is not completely understood yet. Two different molecular routes have been proposed for this, i.e. transcriptional gene silencing (TGS, which is associated with heavy methylation of promoter regions and blocks the transcription of transgene. The basic mechanism underlying post-transcriptional gene silencing (PTGS is degradation of the cytosolic mRNA of transgenes or endogenous genes. Undesired transgene silencing is of a major concern in transgenic technology used in crop improvement. A complete understanding of this phenomenon will be very useful for transgenic applications, where silencing of specific genes are required. The current status of epigenetic silencing in transgenic technology has been discussed and summarized in this mini-review.

  3. Epigenetic silencing in transgenic plants

    Science.gov (United States)

    Rajeevkumar, Sarma; Anunanthini, Pushpanathan; Sathishkumar, Ramalingam

    2015-01-01

    Epigenetic silencing is a natural phenomenon in which the expression of genes is regulated through modifications of DNA, RNA, or histone proteins. It is a mechanism for defending host genomes against the effects of transposable elements and viral infection, and acts as a modulator of expression of duplicated gene family members and as a silencer of transgenes. A major breakthrough in understanding the mechanism of epigenetic silencing was the discovery of silencing in transgenic tobacco plants due to the interaction between two homologous promoters. The molecular mechanism of epigenetic mechanism is highly complicated and it is not completely understood yet. Two different molecular routes have been proposed for this, that is, transcriptional gene silencing, which is associated with heavy methylation of promoter regions and blocks the transcription of transgenes, and post-transcriptional gene silencing (PTGS), the basic mechanism is degradation of the cytosolic mRNA of transgenes or endogenous genes. Undesired transgene silencing is of major concern in the transgenic technologies used in crop improvement. A complete understanding of this phenomenon will be very useful for transgenic applications, where silencing of specific genes is required. The current status of epigenetic silencing in transgenic technology is discussed and summarized in this mini-review. PMID:26442010

  4. RNA silencing and plant viral diseases.

    Science.gov (United States)

    Wang, Ming-Bo; Masuta, Chikara; Smith, Neil A; Shimura, Hanako

    2012-10-01

    RNA silencing plays a critical role in plant resistance against viruses, with multiple silencing factors participating in antiviral defense. Both RNA and DNA viruses are targeted by the small RNA-directed RNA degradation pathway, with DNA viruses being also targeted by RNA-directed DNA methylation. To evade RNA silencing, plant viruses have evolved a variety of counter-defense mechanisms such as expressing RNA-silencing suppressors or adopting silencing-resistant RNA structures. This constant defense-counter defense arms race is likely to have played a major role in defining viral host specificity and in shaping viral and possibly host genomes. Recent studies have provided evidence that RNA silencing also plays a direct role in viral disease induction in plants, with viral RNA-silencing suppressors and viral siRNAs as potentially the dominant players in viral pathogenicity. However, questions remain as to whether RNA silencing is the principal mediator of viral pathogenicity or if other RNA-silencing-independent mechanisms also account for viral disease induction. RNA silencing has been exploited as a powerful tool for engineering virus resistance in plants as well as in animals. Further understanding of the role of RNA silencing in plant-virus interactions and viral symptom induction is likely to result in novel anti-viral strategies in both plants and animals.

  5. Tapping RNA silencing pathways for plant biotechnology.

    Science.gov (United States)

    Frizzi, Alessandra; Huang, Shihshieh

    2010-08-01

    Plants have evolved a variety of gene silencing pathways mediated by small RNAs. Mostly 21 or 24 nt in size, these small RNAs repress the expression of sequence homologous genes at the transcriptional, post-transcriptional and translational levels. These pathways, also referred as RNA silencing pathways, play important roles in regulating growth and development as well as in response to both biotic and abiotic stress. Although the molecular basis of these complicated and interconnected pathways has become clear only in recent years, RNA silencing effects were observed and utilized in transgenic plants early in the plant biotechnology era, more than two decades ago. Today, with a better understanding of the pathways, various genetic engineering approaches have been developed to apply RNA silencing more effectively and broadly. In addition to summarizing the current models of RNA silencing, this review discusses examples of its potential uses and related issues concerning its application in plant biotechnology.

  6. [RNA silencing and viral disease induction in plants].

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    Shimura, Hanako; Masuta, Chikara

    2012-06-01

    RNA silencing plays an important role in plant resistance against viruses. As a counter-defense against RNA silencing, plant viruses have evolved RNA silencing suppressors (RSSs). RNA silencing is likely to play a major role in disease development. For example, RSSs have been found to disturb the gene expression controlled by miRNAs in plant tissue and organ development, resulting in plant malformation. Mosaic symptoms, which are typical in virus-infected plants, are actually a consequence of local arms race between host RNA silencing and viral RSSs. In addition, recent studies revealed that viral siRNAs could induce RNA silencing even against a certain host gene and thus a disease symptom through a complementary (homologous) sequence coincidentally found between virus and host gene. RNA silencing is the principal mediator of viral pathogenicity and disease induction and therefore should be exploited as a powerful tool for engineering virus resistance in plants as well as in animals.

  7. Antiviral RNA silencing viral counter defense in plants

    NARCIS (Netherlands)

    Bucher, E.C.

    2006-01-01

    The research described in this thesis centres around the mechanism of RNA silencing in relation to virus-host interaction, an area of increasing importance. It shows how this recently disclosed mechanism can be used to produce virus-resistant plants. Based on the activity of the RNA silencing machin

  8. Antiviral RNA silencing viral counter defense in plants

    NARCIS (Netherlands)

    Bucher, E.C.

    2006-01-01

    The research described in this thesis centres around the mechanism of RNA silencing in relation to virus-host interaction, an area of increasing importance. It shows how this recently disclosed mechanism can be used to produce virus-resistant plants. Based on the activity of the RNA silencing

  9. Antiviral RNA silencing viral counter defense in plants

    NARCIS (Netherlands)

    Bucher, E.C.

    2006-01-01

    The research described in this thesis centres around the mechanism of RNA silencing in relation to virus-host interaction, an area of increasing importance. It shows how this recently disclosed mechanism can be used to produce virus-resistant plants. Based on the activity of the RNA silencing machin

  10. Micro RNAs and Short-interfering RNAs in Plants

    Institute of Scientific and Technical Information of China (English)

    Ramanjulu Sunkar; Jian-Kang Zhu

    2007-01-01

    Gene silencing can occur either at the transcriptional level or post-transcriptional level or both. Many instances of sequence-specific silencing requires small RNAs that can be divided into two major classes: microRNAs (miRNAs) and short-interfering RNAs (siRNAs). miRNAs function in post-transcriptional gene silencing by guiding mRNA degradation or translational repression. Endogenous siRNAs are more diverse in plants than in animals and can direct post-transcriptional gene silencing through mRNA degradation or transcriptional gene silencing by triggering DNA methylation and histone modifications. This review discusses recent advances in the field of small RNA-guided gene silencing in plants including rice.

  11. Homology-dependent gene silencing and host defense in plants.

    Science.gov (United States)

    Matzke, Marjori A; Aufsatz, Werner; Kanno, Tatsuo; Mette, M Florian; Matzke, Antonius J M

    2002-01-01

    Analyses of transgene silencing phenomena in plants and other organisms have revealed the existence of epigenetic silencing mechanisms that are based on recognition of nucleic acid sequence homology at either the DNA or RNA level. Common triggers of homology-dependent gene silencing include inverted DNA repeats and double-stranded RNA, a versatile silencing molecule that can induce both degradation of homologous RNA in the cytoplasm and methylation of homologous DNA sequences in the nucleus. Inverted repeats might be frequently associated with silencing because they can potentially interact in cis and in trans to trigger DNA methylation via homologous DNA pairing, or they can be transcribed to produce double-stranded RNA. Homology-dependent gene silencing mechanisms are ideally suited for countering natural parasitic sequences such as transposable elements and viruses, which are usually present in multiple copies and/or produce double-stranded RNA during replication. These silencing mechanisms can thus be regarded as host defense strategies to foreign or invasive nucleic acids. The high content of transposable elements and, in some cases, endogenous viruses in many plant genomes suggests that host defenses do not always prevail over invasive sequences. During evolution, slightly faulty genome defense responses probably allowed transposable elements and viral sequences to accumulate gradually in host chromosomes and to invade host genes. Possible beneficial consequences of this "foreign" DNA buildup include the establishment of genome defense-derived epigenetic control mechanisms for regulating host gene expression and acquired hereditary immunity to some viruses.

  12. Silencing and Innate Immunity in Plant Defense Against Viral and Non-Viral Pathogens

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    Anna S. Zvereva

    2012-10-01

    Full Text Available The frontline of plant defense against non-viral pathogens such as bacteria, fungi and oomycetes is provided by transmembrane pattern recognition receptors that detect conserved pathogen-associated molecular patterns (PAMPs, leading to pattern-triggered immunity (PTI. To counteract this innate defense, pathogens deploy effector proteins with a primary function to suppress PTI. In specific cases, plants have evolved intracellular resistance (R proteins detecting isolate-specific pathogen effectors, leading to effector-triggered immunity (ETI, an amplified version of PTI, often associated with hypersensitive response (HR and programmed cell death (PCD. In the case of plant viruses, no conserved PAMP was identified so far and the primary plant defense is thought to be based mainly on RNA silencing, an evolutionary conserved, sequence-specific mechanism that regulates gene expression and chromatin states and represses invasive nucleic acids such as transposons. Endogenous silencing pathways generate 21-24 nt small (sRNAs, miRNAs and short interfering (siRNAs, that repress genes post-transcriptionally and/or transcriptionally. Four distinct Dicer-like (DCL proteins, which normally produce endogenous miRNAs and siRNAs, all contribute to the biogenesis of viral siRNAs in infected plants. Growing evidence indicates that RNA silencing also contributes to plant defense against non-viral pathogens. Conversely, PTI-based innate responses may contribute to antiviral defense. Intracellular R proteins of the same NB-LRR family are able to recognize both non-viral effectors and avirulence (Avr proteins of RNA viruses, and, as a result, trigger HR and PCD in virus-resistant hosts. In some cases, viral Avr proteins also function as silencing suppressors. We hypothesize that RNA silencing and innate immunity (PTI and ETI function in concert to fight plant viruses. Viruses counteract this dual defense by effectors that suppress both PTI-/ETI-based innate responses

  13. Recent patents in RNA silencing in plants: constructs, methods and applications in plant biotechnology.

    Science.gov (United States)

    López-Gomollón, Sara; Dalmay, Tamas

    2010-11-01

    RNA silencing is a recently discovered mechanism to regulate gene expression at transcriptional and posttranscriptional levels. It is based on the recognition and methylation of target genes or cleavage of target mRNAs by small RNA molecules, with length varying from 21 to 24 nucleotides. RNA silencing plays an important role modulating most of the important cell processes, such as growth, development or stress response. During the past few years, diverse strategies have been applied to exploit RNA silencing as a tool to create plants with enhanced economical properties or able to cope with pathogens or abiotic stress. This review describes the most important patents related to RNA silencing in plants, which disclose vectors designed to induce RNA silencing by hairpin RNAs, amplicons or virus-based plasmids, methods for detection and quantification of silencing as well as general uses in plant biotechnology.

  14. Anti-viral RNA silencing: do we look like plants ?

    Directory of Open Access Journals (Sweden)

    Lecellier Charles-Henri

    2006-01-01

    Full Text Available Abstract The anti-viral function of RNA silencing was first discovered in plants as a natural manifestation of the artificial 'co-suppression', which refers to the extinction of endogenous gene induced by homologous transgene. Because silencing components are conserved among most, if not all, eukaryotes, the question rapidly arose as to determine whether this process fulfils anti-viral functions in animals, such as insects and mammals. It appears that, whereas the anti-viral process seems to be similarly conserved from plants to insects, even in worms, RNA silencing does influence the replication of mammalian viruses but in a particular mode: micro(miRNAs, endogenous small RNAs naturally implicated in translational control, rather than virus-derived small interfering (siRNAs like in other organisms, are involved. In fact, these recent studies even suggest that RNA silencing may be beneficial for viral replication. Accordingly, several large DNA mammalian viruses have been shown to encode their own miRNAs. Here, we summarize the seminal studies that have implicated RNA silencing in viral infection and compare the different eukaryotic responses.

  15. A modular plasmid assembly kit for multigene expression, gene silencing and silencing rescue in plants.

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    Andreas Binder

    Full Text Available The Golden Gate (GG modular assembly approach offers a standardized, inexpensive and reliable way to ligate multiple DNA fragments in a pre-defined order in a single-tube reaction. We developed a GG based toolkit for the flexible construction of binary plasmids for transgene expression in plants. Starting from a common set of modules, such as promoters, protein tags and transcribed regions of interest, synthetic genes are assembled, which can be further combined to multigene constructs. As an example, we created T-DNA constructs encoding multiple fluorescent proteins targeted to distinct cellular compartments (nucleus, cytosol, plastids and demonstrated simultaneous expression of all genes in Nicotiana benthamiana, Lotus japonicus and Arabidopsis thaliana. We assembled an RNA interference (RNAi module for the construction of intron-spliced hairpin RNA constructs and demonstrated silencing of GFP in N. benthamiana. By combination of the silencing construct together with a codon adapted rescue construct into one vector, our system facilitates genetic complementation and thus confirmation of the causative gene responsible for a given RNAi phenotype. As proof of principle, we silenced a destabilized GFP gene (dGFP and restored GFP fluorescence by expression of a recoded version of dGFP, which was not targeted by the silencing construct.

  16. Viral counterdefense on RNA silencing : analysis of RNA silencing suppressors from arthropod-borne negative strand RNA plant viruses

    NARCIS (Netherlands)

    Schnettler, E.

    2010-01-01

    This thesis describes that RNA silencing suppressor (RSS) proteins encoded by negative-stranded RNA plant viruses are able to interfere with different RNA silencing pathways in a variety of organisms by interacting with double stranded (ds)RNA molecules. These RSS proteins are able to counteract the

  17. Viral counterdefense on RNA silencing : analysis of RNA silencing suppressors from arthropod-borne negative strand RNA plant viruses

    NARCIS (Netherlands)

    Schnettler, E.

    2010-01-01

    This thesis describes that RNA silencing suppressor (RSS) proteins encoded by negative-stranded RNA plant viruses are able to interfere with different RNA silencing pathways in a variety of organisms by interacting with double stranded (ds)RNA molecules. These RSS proteins are able to counteract the

  18. Regeneration of transgenic citrus plants under non selective conditions results in high-frequency recovery of plants with silenced transgenes.

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    Domínguez, A; Fagoaga, C; Navarro, L; Moreno, P; Peña, L

    2002-06-01

    Insertion of foreign DNA into plant genomes frequently results in the recovery of transgenic plants with silenced transgenes. To investigate to what extent regeneration under selective conditions limits the recovery of transgenic plants showing gene silencing in woody species, Mexican lime [ Citrus aurantifolia (Christm.) Swing.] plants were transformed with the p25 coat protein gene of Citrus tristeza virus (CTV) with or without selection for nptII and uidA. Strikingly, more than 30% of the transgenic limes regenerated under non-selective conditions had silenced transgenes, and in all cases silencing affected all the three transgenes incorporated. These results indicate that the frequency of transgene silencing may be greatly underestimated when the rate of silencing is estimated from the number of regenerants obtained under selective conditions. To our knowledge, this is the first report in which the frequency of gene silencing after transformation has been quantified. When the integration pattern of T-DNA was analyzed in silenced and non-silenced lines, it was observed that inverted repeats as well as direct repeats and even single integrations were able to trigger gene silencing. Gene silencing has often been associated with the insertion of DNA sequences as inverted repeats. Interestingly, here, direct repeats and single-copy insertions were found in both silenced and non-silenced lines, suggesting that the presence of inverted-repeat T-DNAs and the subsequent formation of dsRNAs triggering gene silencing cannot account for all silencing events.

  19. Visualization of plant viral suppressor silencing activity in intact leaf lamina by quantitative fluorescent imaging

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    Francis Kevin P

    2011-08-01

    Full Text Available Abstract Background Transient expression of proteins in plants has become a favoured method over the production of stably transformed plants because, in addition to enabling high protein yields, it is both fast and easy to apply. An enhancement of transient protein expression can be achieved by plant virus-encoded RNA silencing suppressor proteins. Since viral suppressor proteins differ in their efficiency to enhance transient protein expression in plants, we developed a whole-leaf green fluorescent protein (GFP-based imaging assay to quantitatively assess suppressor protein activity. Results In a transient GFP-expression assay using wild-type and GFP-transgenic N. benthamiana, addition of the plant viral suppressors Beet mild yellowing virus (BMYV-IPP P0 or Plum pox virus (PPV HC-Pro was shown to increase fluorescent protein expression 3-4-fold, 7 days post inoculation (dpi when compared to control plants. In contrast, in agroinfiltrated patches without suppressor activity, near complete silencing of the GFP transgene was observed in the transgenic N. benthamiana at 21 dpi. Both co-infiltrated suppressors significantly enhanced GFP expression over time, with HC-Pro co-infiltrations leading to higher short term GFP fluorescence (at 7 dpi and P0 giving higher long term GFP fluorescence (at 21 dpi. Additionally, in contrast to HC-Pro co-infiltrations, an area of complete GFP silencing was observed at the edge of P0 co-infiltrated areas. Conclusions Fluorescence imaging of whole intact leaves proved to be an easy and effective method for spatially and quantitatively observing viral suppressor efficiency in plants. This suppressor assay demonstrates that plant viral suppressors greatly enhanced transient GFP expression, with P0 showing a more prolonged suppressor activity over time than HC-Pro. Both suppressors could prove to be ideal candidates for enhancing target protein expression in plants.

  20. Characteristics of RNA silencing in plants: similarities and differences across kingdoms.

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    Susi, P; Hohkuri, M; Wahlroos, T; Kilby, N J

    2004-01-01

    RNA silencing is a collective term that encompasses the sequence of events that leads to the targeted degradation of cellular mRNA and thus to the silencing of corresponding gene expression. RNA silencing is initiated after introduction into the host genome of a gene that is homologous to an endogenous gene. Transcription of the introduced gene results in the formation of double-stranded RNA (dsRNA) that is cut into smaller dsRNA species termed small interfering RNAs (siRNAs) by an RNaseIII-like enzyme called 'Dicer'. siRNAs associate with a protein complex termed the 'RNA-induced silencing complex' (RISC), which mediates the binding of one strand of siRNAs with mRNAs transcribed from the native 'target' gene. The binding of siRNAs with native gene mRNAs earmarks native gene mRNAs for destruction, resulting in gene silencing. In plants, RNA silencing appears to serve as a defence mechanism against viral pathogens and also to suppress the activity of virus-like mobile genetic elements. In an apparent response to RNA silencing, some plant viruses express suppressors of RNA silencing. RNA silencing also is directly implicated in the regulation of the function(s) of microRNAs, which are the key determinants in an additional cellular mechanism related to the translational repression of genes, the effect of which ultimately impinges on development. The high degree of sequence similarity that exists between genes involved in RNA silencing in widely different organisms underscores the conserved nature of many aspects of the RNA silencing mechanism. However, depending (for example) on the precise nature of the target gene involved, there also are significant differences in the silencing pathways that are engaged by various organisms.

  1. Endogenous, tissue-specific short interfering RNAs silence the chalcone synthase gene family in glycine max seed coats.

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    Tuteja, Jigyasa H; Zabala, Gracia; Varala, Kranthi; Hudson, Matthew; Vodkin, Lila O

    2009-10-01

    Two dominant alleles of the I locus in Glycine max silence nine chalcone synthase (CHS) genes to inhibit function of the flavonoid pathway in the seed coat. We describe here the intricacies of this naturally occurring silencing mechanism based on results from small RNA gel blots and high-throughput sequencing of small RNA populations. The two dominant alleles of the I locus encompass a 27-kb region containing two perfectly repeated and inverted clusters of three chalcone synthase genes (CHS1, CHS3, and CHS4). This structure silences the expression of all CHS genes, including CHS7 and CHS8, located on other chromosomes. The CHS short interfering RNAs (siRNAs) sequenced support a mechanism by which RNAs transcribed from the CHS inverted repeat form aberrant double-stranded RNAs that become substrates for dicer-like ribonuclease. The resulting primary siRNAs become guides that target the mRNAs of the nonlinked, highly expressed CHS7 and CHS8 genes, followed by subsequent amplification of CHS7 and CHS8 secondary siRNAs by RNA-dependent RNA polymerase. Most remarkably, this silencing mechanism occurs only in one tissue, the seed coat, as shown by the lack of CHS siRNAs in cotyledons and vegetative tissues. Thus, production of the trigger double-stranded RNA that initiates the process occurs in a specific tissue and represents an example of naturally occurring inhibition of a metabolic pathway by siRNAs in one tissue while allowing expression of the pathway and synthesis of valuable secondary metabolites in all other organs/tissues of the plant.

  2. Artificial microRNA mediated gene silencing in plants: progress and perspectives.

    Science.gov (United States)

    Tiwari, Manish; Sharma, Deepika; Trivedi, Prabodh Kumar

    2014-09-01

    Homology based gene silencing has emerged as a convenient approach for repressing expression of genes in order to study their functions. For this purpose, several antisense or small interfering RNA based gene silencing techniques have been frequently employed in plant research. Artificial microRNAs (amiRNAs) mediated gene silencing represents one of such techniques which can utilize as a potential tool in functional genomics. Similar to microRNAs, amiRNAs are single-stranded, approximately 21 nt long, and designed by replacing the mature miRNA sequences of duplex within pre-miRNAs. These amiRNAs are processed via small RNA biogenesis and silencing machinery and deregulate target expression. Holding to various refinements, amiRNA technology offers several advantages over other gene silencing methods. This is a powerful and robust tool, and could be applied to unravel new insight of metabolic pathways and gene functions across the various disciplines as well as in translating observations for improving favourable traits in plants. This review highlights general background of small RNAs, improvements made in RNAi based gene silencing, implications of amiRNA in gene silencing, and describes future themes for improving value of this technology in plant science.

  3. Host-delivered RNAi: an effective strategy to silence genes in plant parasitic nematodes.

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    Fairbairn, David J; Cavallaro, Antonino S; Bernard, Margaret; Mahalinga-Iyer, Janani; Graham, Michael W; Botella, José R

    2007-11-01

    Root-knot nematodes (Meloidogyne spp.) are obligate, sedentary endoparasites that infect many plant species causing large economic losses worldwide. Available nematicides are being banned due to their toxicity or ozone-depleting properties and alternative control strategies are urgently required. We have produced transgenic tobacco (Nicotiana tabacum) plants expressing different dsRNA hairpin structures targeting a root-knot nematode (Meloidogyne javanica) putative transcription factor, MjTis11. We provide evidence that MjTis11 was consistently silenced in nematodes feeding on the roots of transgenic plants. The observed silencing was specific for MjTis11, with other sequence-unrelated genes being unaffected in the nematodes. Those transgenic plants able to induce silencing of MjTis11, also showed the presence of small interfering RNAs. Even though down-regulation of MjTis11 did not result in a lethal phenotype, this study demonstrates the feasibility of silencing root-knot nematode genes by expressing dsRNA in the host plant. Host-delivered RNA interference-triggered (HD-RNAi) silencing of parasite genes provides a novel disease resistance strategy with wide biotechnological applications. The potential of HD-RNAi is not restricted to parasitic nematodes but could be adapted to control other plant-feeding pests.

  4. Supervised learning classification models for prediction of plant virus encoded RNA silencing suppressors.

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    Zeenia Jagga

    Full Text Available Viral encoded RNA silencing suppressor proteins interfere with the host RNA silencing machinery, facilitating viral infection by evading host immunity. In plant hosts, the viral proteins have several basic science implications and biotechnology applications. However in silico identification of these proteins is limited by their high sequence diversity. In this study we developed supervised learning based classification models for plant viral RNA silencing suppressor proteins in plant viruses. We developed four classifiers based on supervised learning algorithms: J48, Random Forest, LibSVM and Naïve Bayes algorithms, with enriched model learning by correlation based feature selection. Structural and physicochemical features calculated for experimentally verified primary protein sequences were used to train the classifiers. The training features include amino acid composition; auto correlation coefficients; composition, transition, and distribution of various physicochemical properties; and pseudo amino acid composition. Performance analysis of predictive models based on 10 fold cross-validation and independent data testing revealed that the Random Forest based model was the best and achieved 86.11% overall accuracy and 86.22% balanced accuracy with a remarkably high area under the Receivers Operating Characteristic curve of 0.95 to predict viral RNA silencing suppressor proteins. The prediction models for plant viral RNA silencing suppressors can potentially aid identification of novel viral RNA silencing suppressors, which will provide valuable insights into the mechanism of RNA silencing and could be further explored as potential targets for designing novel antiviral therapeutics. Also, the key subset of identified optimal features may help in determining compositional patterns in the viral proteins which are important determinants for RNA silencing suppressor activities. The best prediction model developed in the study is available as a

  5. Heterologous expression of plant virus genes that suppress post-transcriptional gene silencing results in suppression of RNA interference in Drosophila cells

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    Canto Tomas

    2004-08-01

    Full Text Available Abstract Background RNA interference (RNAi in animals and post-transcriptional gene silencing (PTGS in plants are related phenomena whose functions include the developmental regulation of gene expression and protection from transposable elements and viruses. Plant viruses respond by expressing suppressor proteins that interfere with the PTGS system. Results Here we demonstrate that both transient and constitutive expression of the Tobacco etch virus HC-Pro silencing suppressor protein, which inhibits the maintenance of PTGS in plants, prevents dsRNA-induced RNAi of a lacZ gene in cultured Drosophila cells. Northern blot analysis of the RNA present in Drosophila cells showed that HC-Pro prevented degradation of lacZ RNA during RNAi but that there was accumulation of the short (23nt RNA species associated with RNAi. A mutant HC-Pro that does not suppress PTGS in plants also does not affect RNAi in Drosophila. Similarly, the Cucumber mosaic virus 2b protein, which inhibits the systemic spread of PTGS in plants, does not suppress RNAi in Drosophila cells. In addition, we have used the Drosophila system to demonstrate that the 16K cysteine-rich protein of Tobacco rattle virus, which previously had no known function, is a silencing suppressor protein. Conclusion These results indicate that at least part of the process of RNAi in Drosophila and PTGS in plants is conserved, and that plant virus silencing suppressor proteins may be useful tools to investigate the mechanism of RNAi.

  6. Chemical induction of hairpin RNAi molecules to silence vital genes in plant roots.

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    Liu, Siming; Yoder, John I

    2016-11-29

    Understanding the functions encoded by plant genes can be facilitated by reducing transcript levels by hairpin RNA (hpRNA) mediated silencing. A bottleneck to this technology occurs when a gene encodes a phenotype that is necessary for cell viability and silencing the gene inhibits transformation. Here we compared the use of two chemically inducible plant promoter systems to drive hpRNA mediated gene silencing in transgenic, hairy roots. We cloned the gene encoding the Yellow Fluorescence Protein (YFP) into the dexamethasone inducible vector pOpOff2 and into the estradiol induced vector pER8. We then cloned a hpRNA targeting YFP under the regulation of the inducible promoters, transformed Medicago truncatula roots, and quantified YFP fluorescence and mRNA levels. YFP fluorescence was normal in pOpOff2 transformed roots without dexamethasone but was reduced with dexamethasone treatment. Interestingly, dexamethasone removal did not reverse YFP inhibition. YFP expression in roots transformed with pER8 was low even in the absence of inducer. We used the dexamethasone system to silence acetyl-CoA carboxylase gene and observed prolific root growth when this construct was transformed into Medicago until dexamethasone was applied. Our study shows that dexamethasone inducibility can be useful to silence vital genes in transgenic roots.

  7. Detailed characterization of the posttranscriptional gene-silencing-related small RNA in a GUS gene-silenced tobacco

    NARCIS (Netherlands)

    Hutvágner, G.; Mlynarova, L.; Nap, J.P.H.

    2000-01-01

    Posttranscriptional gene-silencing phenomena such as cosuppression and RNA interference are associated with the occurrence of small, about 21-23 nt short RNA species homologous to the silenced gene. We here show that the small RNA present in silenced transgenic plants can easily be detected in total

  8. Comparative analysis of RNA silencing suppression activities between viral suppressors and an endogenous plant RNA-dependent RNA polymerase.

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    Yoon, Ju-Yeon; Han, Kyoung-Sik; Park, Han-Yong; Choi, Seung-Kook

    2012-06-01

    RNA silencing is an evolutionarily conserved system that functions as an antiviral mechanism in eukaryotes, including higher plants. To counteract this, several plant viruses express silencing suppressors that inhibit RNA silencing in host plants. Here, we show that both 2b protein from peanut stunt virus (PSV) and a hairpin construct (designated hp-RDR6) that silences endogenous RNA-dependent RNA polymerase 6 (RDR6) strongly suppress RNA silencing. The Agrobacterium infiltration system was used to demonstrate that both PSV 2b and hp-RDR6 suppressed local RNA silencing as strongly as helper component (HC-Pro) from potato virus Y (PVY) and P19 from tomato bush stunt virus (TBSV). The 2b protein from PSV eliminated the small-interfering RNAs (siRNAs) associated with RNA silencing and prevented systemic silencing, similar to 2b protein from cucumber mosaic virus (CMV). On the other hand, hp-RDR6 suppressed RNA silencing by inhibiting the generation of secondary siRNAs. The small coat protein (SCP) of squash mosaic virus (SqMV) also displayed weak suppression activity of RNA silencing. Agrobacterium-mediated gene transfer was used to investigate whether viral silencing suppressors or hp-RDR6 enhanced accumulations of green fluorescence protein (GFP) and β-glucuronidase (GUS) as markers of expression in leaf tissues of Nicotina benthamiana. Expression of both GFP and GUS was significantly enhanced in the presence of PSV 2b or CMV 2b, compared to no suppression or the weak SqMV SCP suppressor. Co-expression with hp-RDR6 also significantly increased the expression of GFP and GUS to levels similar to those induced by PVY HC-Pro and TBSV P19.

  9. RNAi Codex: a portal/database for short-hairpin RNA (shRNA) gene-silencing constructs.

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    Olson, A; Sheth, N; Lee, J S; Hannon, G; Sachidanandam, R

    2006-01-01

    Use of RNA interference (RNAi) in forward genetic screens is proliferating. Currently, short-interfering RNAs (siRNAs) and short-hairpin RNAs (shRNAs) are being used to silence genes to tease out functional information. It is becoming easier to harness RNAi to silence specific genes, owing to the development of libraries of readymade shRNA and siRNA gene-silencing constructs by using a variety of sources. RNAi Codex, which consists of a database of shRNA related information and an associated website, has been developed as a portal for publicly available shRNA resources and is accessible at http://codex.cshl.org. RNAi Codex currently holds data from the Hannon-Elledge shRNA library and allows the use of biologist-friendly gene names to access information on shRNA constructs that can silence the gene of interest. It is designed to hold user-contributed annotations and publications for each construct, as and when such data become available. We will describe features of RNAi Codex and explain the use of the tool.

  10. Interaction between viral RNA silencing suppressors and host factors in plant immunity.

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    Nakahara, Kenji S; Masuta, Chikara

    2014-08-01

    To elucidate events in the molecular arms race between the host and pathogen in evaluating plant immunity, a zigzag model is useful for uncovering aspects common to different host-pathogen interactions. By analogy of the steps in virus-host interactions with the steps in the standard zigzag model outlined in recent papers, we may regard RNA silencing as pattern-triggered immunity (PTI) against viruses, RNA silencing suppressors (RSSs) as effectors to overcome host RNA silencing and resistance gene (R-gene)-mediated defense as effector-triggered immunity (ETI) recognizing RSSs as avirulence proteins. However, because the standard zigzag model does not fully apply to some unique aspects in the interactions between a plant host and virus, we here defined a model especially designed for viruses. Although we simplified the phenomena involved in the virus-host interactions in the model, certain specific interactive steps can be explained by integrating additional host factors into the model. These host factors are thought to play an important role in maintaining the efficacy of the various steps in the main pathway of defense against viruses in this model for virus-plant interactions. For example, we propose candidates that may interact with viral RSSs to induce the resistance response. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Heat-induced release of epigenetic silencing reveals the concealed role of an imprinted plant gene.

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    Diego H Sanchez

    2014-11-01

    Full Text Available Epigenetic mechanisms suppress the transcription of transposons and DNA repeats; however, this suppression can be transiently released under prolonged heat stress. Here we show that the Arabidopsis thaliana imprinted gene SDC, which is silent during vegetative growth due to DNA methylation, is activated by heat and contributes to recovery from stress. SDC activation seems to involve epigenetic mechanisms but not canonical heat-shock perception and signaling. The heat-mediated transcriptional induction of SDC occurs particularly in young developing leaves and is proportional to the level of stress. However, this occurs only above a certain window of absolute temperatures and, thus, resembles a thermal-sensing mechanism. In addition, the re-silencing kinetics during recovery can be entrained by repeated heat stress cycles, suggesting that epigenetic regulation in plants may conserve memory of stress experience. We further demonstrate that SDC contributes to the recovery of plant biomass after stress. We propose that transcriptional gene silencing, known to be involved in gene imprinting, is also co-opted in the specific tuning of SDC expression upon heat stress and subsequent recovery. It is therefore possible that dynamic properties of the epigenetic landscape associated with silenced or imprinted genes may contribute to regulation of their expression in response to environmental challenges.

  12. Plant-mediated gene silencing restricts growth of the potato late blight pathogen Phytophthora infestans.

    Science.gov (United States)

    Jahan, Sultana N; Åsman, Anna K M; Corcoran, Pádraic; Fogelqvist, Johan; Vetukuri, Ramesh R; Dixelius, Christina

    2015-05-01

    Phytophthora infestans is an oomycete that causes severe damage to potato, and is well known for its ability to evolve rapidly in order to overcome resistant potato varieties. An RNA silencing strategy was evaluated here to clarify if small interfering RNA homologous to selected genes in P. infestans could be targeted from the plant host to reduce the magnitude of the infection. As a proof-of-concept, a hairpin RNA (hp-RNA) construct using the GFP marker gene was designed and introduced in potato. At 72 hpi, a 55-fold reduction of the signal intensity of a corresponding GFP expressing P. infestans strain on leaf samples of transgenic plants, compared with wild-type potato, was detected. This suggests that an RNA interference construct in the potato host could be processed and target a transcript of the pathogen. Three genes important in the infection process of P. infestans, PiGPB1, PiCESA2, and PiPEC, together with PiGAPDH taking part in basic cell maintenance were subsequently tested using an analogous transgenic strategy. Out of these gene candidates, the hp-PiGPB1 targeting the G protein β-subunit (PiGPB1) important for pathogenicity resulted in most restricted disease progress. Further, Illumina sequencing of inoculated transgenic potato leaves revealed sRNAs of 24/25 nt size homologous to the PiGPB1 gene in the transgenic plants indicating post-transcriptional silencing of the target gene. The work demonstrates that a host-induced gene-silencing approach is functional against P. infestans but is highly dependent on target gene for a successful outcome. This finding broadens the arsenal of control strategies to this important plant disease.

  13. Mitochondrial GPX1 silencing triggers differential photosynthesis impairment in response to salinity in rice plants.

    Science.gov (United States)

    Lima-Melo, Yugo; Carvalho, Fabricio E L; Martins, Márcio O; Passaia, Gisele; Sousa, Rachel H V; Neto, Milton C Lima; Margis-Pinheiro, Márcia; Silveira, Joaquim A G

    2016-08-01

    The physiological role of plant mitochondrial glutathione peroxidases is scarcely known. This study attempted to elucidate the role of a rice mitochondrial isoform (GPX1) in photosynthesis under normal growth and salinity conditions. GPX1 knockdown rice lines (GPX1s) were tested in absence and presence of 100 mM NaCl for 6 d. Growth reduction of GPX1s line under non-stressful conditions, compared with non-transformed (NT) plants occurred in parallel to increased H2 O2 and decreased GSH contents. These changes occurred concurrently with photosynthesis impairment, particularly in Calvin cycle's reactions, since photochemical efficiency did not change. Thus, GPX1 silencing and downstream molecular/metabolic changes modulated photosynthesis differentially. In contrast, salinity induced reduction in both phases of photosynthesis, which were more impaired in silenced plants. These changes were associated with root morphology alterations but not shoot growth. Both studied lines displayed increased GPX activity but H2 O2 content did not change in response to salinity. Transformed plants exhibited lower photorespiration, water use efficiency and root growth, indicating that GPX1 could be important to salt tolerance. Growth reduction of GPX1s line might be related to photosynthesis impairment, which in turn could have involved a cross talk mechanism between mitochondria and chloroplast originated from redox changes due to GPX1 deficiency.

  14. Virus induced gene silencing of three putative prolyl 4-hydroxylases enhances plant growth in tomato (Solanum lycopersicum).

    Science.gov (United States)

    Fragkostefanakis, Sotirios; Sedeek, Khalid E M; Raad, Maya; Zaki, Marwa Samir; Kalaitzis, Panagiotis

    2014-07-01

    Proline hydroxylation is a major posttranslational modification of hydroxyproline-rich glycoproteins (HRGPs) that is catalyzed by prolyl 4-hydroxylases (P4Hs). HRGPs such as arabinogalactan proteins (AGPs) and extensios play significant roles on cell wall structure and function and their implication in cell division and expansion has been reported. We used tobacco rattle virus (TRV)-based virus induced gene silencing to investigate the role of three tomato P4Hs, out of ten present in the tomato genome, in growth and development. Eight-days old tomato seedlings were infected with the appropriate TRV vectors and plants were allowed to grow under standard conditions for 6 weeks. Lower P4H mRNA levels were associated with lower hydroxyproline content in root and shoot tissues indicating successful gene silencing. P4H-silenced plants had longer roots and shoots and larger leaves. The increased leaf area can be attributed to increased cell division as indicated by the higher leaf epidermal cell number in SlP4H1- and SlP4H9-silenced plants. In contrast, SlP4H7-silenced plants had larger leaves due to enhanced cell expansion. Western blot analysis revealed that silencing of SlP4H7 and SlP4H9 was associated with reduced levels of JIM8-bound AGP and JIM11-bound extensin epitopes, while silencing of SlP4H1 reduced only the levels of AGP proteins. Collectively these results show that P4Hs have significant and distinct roles in cell division and expansion of tomato leaves.

  15. Induction and maintenance of DNA methylation in plant promoter sequences by apple latent spherical virus-induced transcriptional gene silencing

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    Tatsuya eKon

    2014-11-01

    Full Text Available Apple latent spherical virus (ALSV is an efficient virus-induced gene silencing vector in functional genomics analyses of a broad range of plant species. Here, an Agrobacterium-mediated inoculation (agroinoculation system was developed for the ALSV vector, and virus-induced transcriptional gene silencing (VITGS is described in plants infected with the ALSV vector. The cDNAs of ALSV RNA1 and RNA2 were inserted between the CaMV 35S promoter and the NOS-T sequences in a binary vector pCAMBIA1300 to produce pCALSR1 and pCALSR2-XSB or pCALSR2-XSB/MN. When these vector constructs were agroinoculated into Nicotiana benthamiana plants with a construct expressing a viral silencing suppressor, the infection efficiency of the vectors was 100%. A recombinant ALSV vector carrying part of the 35S promoter sequence induced transcriptional gene silencing of the green fluorescent protein gene in a line of N. benthamiana plants, resulting in the disappearance of green fluorescence of infected plants. Bisulfite sequencing showed that cytosine residues at CG and CHG sites of the 35S promoter sequence were highly methylated in the silenced generation 0 plants infected with the ALSV carrying the promoter sequence as well as in progeny. The ALSV-mediated VITGS state was inherited by progeny for multiple generations. In addition, induction of VITGS of an endogenous gene (chalcone synthase-A was demonstrated in petunia plants infected with an ALSV vector carrying the native promoter sequence. These results suggest that ALSV-based vectors can be applied to study DNA methylation in plant genomes, and provide a useful tool for plant breeding via epigenetic modification.

  16. Comprehensive protein-based artificial microRNA screens for effective gene silencing in plants.

    Science.gov (United States)

    Li, Jian-Feng; Chung, Hoo Sun; Niu, Yajie; Bush, Jenifer; McCormack, Matthew; Sheen, Jen

    2013-05-01

    Artificial microRNA (amiRNA) approaches offer a powerful strategy for targeted gene manipulation in any plant species. However, the current unpredictability of amiRNA efficacy has limited broad application of this promising technology. To address this, we developed epitope-tagged protein-based amiRNA (ETPamir) screens, in which target mRNAs encoding epitope-tagged proteins were constitutively or inducibly coexpressed in protoplasts with amiRNA candidates targeting single or multiple genes. This design allowed parallel quantification of target proteins and mRNAs to define amiRNA efficacy and mechanism of action, circumventing unpredictable amiRNA expression/processing and antibody unavailability. Systematic evaluation of 63 amiRNAs in 79 ETPamir screens for 16 target genes revealed a simple, effective solution for selecting optimal amiRNAs from hundreds of computational predictions, reaching ∼100% gene silencing in plant cells and null phenotypes in transgenic plants. Optimal amiRNAs predominantly mediated highly specific translational repression at 5' coding regions with limited mRNA decay or cleavage. Our screens were easily applied to diverse plant species, including Arabidopsis thaliana, tobacco (Nicotiana benthamiana), tomato (Solanum lycopersicum), sunflower (Helianthus annuus), Catharanthus roseus, maize (Zea mays) and rice (Oryza sativa), and effectively validated predicted natural miRNA targets. These screens could improve plant research and crop engineering by making amiRNA a more predictable and manageable genetic and functional genomic technology.

  17. rgs-CaM Detects and Counteracts Viral RNA Silencing Suppressors in Plant Immune Priming.

    Science.gov (United States)

    Jeon, Eun Jin; Tadamura, Kazuki; Murakami, Taiki; Inaba, Jun-Ichi; Kim, Bo Min; Sato, Masako; Atsumi, Go; Kuchitsu, Kazuyuki; Masuta, Chikara; Nakahara, Kenji S

    2017-10-01

    Primary infection of a plant with a pathogen that causes high accumulation of salicylic acid in the plant typically via a hypersensitive response confers enhanced resistance against secondary infection with a broad spectrum of pathogens, including viruses. This phenomenon is called systemic acquired resistance (SAR), which is a plant priming for adaption to repeated biotic stress. However, the molecular mechanisms of SAR-mediated enhanced inhibition, especially of virus infection, remain unclear. Here, we show that SAR against cucumber mosaic virus (CMV) in tobacco plants (Nicotiana tabacum) involves a calmodulin-like protein, rgs-CaM. We previously reported the antiviral function of rgs-CaM, which binds to and directs degradation of viral RNA silencing suppressors (RSSs), including CMV 2b, via autophagy. We found that rgs-CaM-mediated immunity is ineffective against CMV infection in normally growing tobacco plants but is activated as a result of SAR induction via salicylic acid signaling. We then analyzed the effect of overexpression of rgs-CaM on salicylic acid signaling. Overexpressed and ectopically expressed rgs-CaM induced defense reactions, including cell death, generation of reactive oxygen species, and salicylic acid signaling. Further analysis using a combination of the salicylic acid analogue benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) and the Ca(2+) ionophore A23187 revealed that rgs-CaM functions as an immune receptor that induces salicylic acid signaling by simultaneously perceiving both viral RSS and Ca(2+) influx as infection cues, implying its autoactivation. Thus, secondary infection of SAR-induced tobacco plants with CMV seems to be effectively inhibited through 2b recognition and degradation by rgs-CaM, leading to reinforcement of antiviral RNA silencing and other salicylic acid-mediated antiviral responses.IMPORTANCE Even without an acquired immune system like that in vertebrates, plants show enhanced whole-plant

  18. Efficient gene silencing mediated by tobacco rattle virus in an emerging model plant physalis.

    Directory of Open Access Journals (Sweden)

    Ji-Si Zhang

    Full Text Available The fruit of Physalis has a berry and a novelty called inflated calyx syndrome (ICS, also named the 'Chinese lantern'. Elucidation of the underlying developmental mechanisms of fruit diversity demands an efficient gene functional inference platform. Here, we tested the application of the tobacco rattle virus (TRV-mediated gene-silencing system in Physalis floridana. First, we characterized the putative gene of a phytoene desaturase in P. floridana (PfPDS. Infecting the leaves of the Physalis seedlings with the PfPDS-TRV vector resulted in a bleached plant, including the developing leaves, floral organs, ICS, berry, and seed. These results indicated that a local VIGS treatment can efficiently induce a systemic mutated phenotype. qRT-PCR analyses revealed that the bleaching extent correlated to the mRNA reduction of the endogenous PfPDS. Detailed comparisons of multiple infiltration and growth protocols allowed us to determine the optimal methodologies for VIGS manipulation in Physalis. We subsequently utilized this optimized VIGS methodology to downregulate the expression of two MADS-box genes, MPF2 and MPF3, and compared the resulting effects with gene-downregulation mediated by RNA interference (RNAi methods. The VIGS-mediated gene knockdown plants were found to resemble the mutated phenotypes of floral calyx, fruiting calyx and pollen maturation of the RNAi transgenic plants for both MPF2 and MPF3. Moreover, the two MADS-box genes were appeared to have a novel role in the pedicel development in P. floridana. The major advantage of VIGS-based gene knockdown lies in practical aspects of saving time and easy manipulation as compared to the RNAi. Despite the lack of heritability and mosaic mutation phenotypes observed in some organs, the TRV-mediated gene silencing system provides an alternative efficient way to infer gene function in various developmental processes in Physalis, thus facilitating understanding of the genetic basis of the evolution

  19. Efficient gene silencing mediated by tobacco rattle virus in an emerging model plant physalis.

    Science.gov (United States)

    Zhang, Ji-Si; Zhao, Jing; Zhang, Shaohua; He, Chaoying

    2014-01-01

    The fruit of Physalis has a berry and a novelty called inflated calyx syndrome (ICS, also named the 'Chinese lantern'). Elucidation of the underlying developmental mechanisms of fruit diversity demands an efficient gene functional inference platform. Here, we tested the application of the tobacco rattle virus (TRV)-mediated gene-silencing system in Physalis floridana. First, we characterized the putative gene of a phytoene desaturase in P. floridana (PfPDS). Infecting the leaves of the Physalis seedlings with the PfPDS-TRV vector resulted in a bleached plant, including the developing leaves, floral organs, ICS, berry, and seed. These results indicated that a local VIGS treatment can efficiently induce a systemic mutated phenotype. qRT-PCR analyses revealed that the bleaching extent correlated to the mRNA reduction of the endogenous PfPDS. Detailed comparisons of multiple infiltration and growth protocols allowed us to determine the optimal methodologies for VIGS manipulation in Physalis. We subsequently utilized this optimized VIGS methodology to downregulate the expression of two MADS-box genes, MPF2 and MPF3, and compared the resulting effects with gene-downregulation mediated by RNA interference (RNAi) methods. The VIGS-mediated gene knockdown plants were found to resemble the mutated phenotypes of floral calyx, fruiting calyx and pollen maturation of the RNAi transgenic plants for both MPF2 and MPF3. Moreover, the two MADS-box genes were appeared to have a novel role in the pedicel development in P. floridana. The major advantage of VIGS-based gene knockdown lies in practical aspects of saving time and easy manipulation as compared to the RNAi. Despite the lack of heritability and mosaic mutation phenotypes observed in some organs, the TRV-mediated gene silencing system provides an alternative efficient way to infer gene function in various developmental processes in Physalis, thus facilitating understanding of the genetic basis of the evolution and development

  20. Elucidating the role of highly homologous Nicotiana benthamiana ubiquitin E2 gene family members in plant immunity through an improved virus-induced gene silencing approach.

    Science.gov (United States)

    Zhou, Bangjun; Zeng, Lirong

    2017-01-01

    Virus-induced gene silencing (VIGS) has been used in many plant species as an attractive post transcriptional gene silencing (PTGS) method for studying gene function either individually or at large-scale in a high-throughput manner. However, the specificity and efficiency for knocking down members of a highly homologous gene family have remained to date a significant challenge in VIGS due to silencing of off-targets. Here we present an improved method for the selection and evaluation of gene fragments used for VIGS to specifically and efficiently knock down members of a highly homologous gene family. Using this method, we knocked down twelve and four members, respectively of group III of the gene family encoding ubiquitin-conjugating enzymes (E2) in Nicotiana benthamiana. Assays using these VIGS-treated plants revealed that the group III E2s are essential for plant development, plant immunity-associated reactive oxygen species (ROS) production, expression of the gene NbRbohB that is required for ROS production, and suppression of immunity-associated programmed cell death (PCD) by AvrPtoB, an effector protein of the bacterial pathogen Pseudomons syringae. Moreover, functional redundancy for plant development and ROS production was found to exist among members of group III E2s. We have found that employment of a gene fragment as short as approximately 70 base pairs (bp) that contains at least three mismatched nucleotides to other genes within any 21-bp sequences prevents silencing of off-target(s) in VIGS. This improved approach in the selection and evaluation of gene fragments allows for specific and efficient knocking down of highly homologous members of a gene family. Using this approach, we implicated N. benthamiana group III E2s in plant development, immunity-associated ROS production, and suppression of multiple immunity-associated PCD by AvrPtoB. We also unraveled functional redundancy among group III members in their requirement for plant development and

  1. Silencing of the AV2 gene by antisense RNA protects transgenic plants against a bipartite begomovirus

    Directory of Open Access Journals (Sweden)

    Zafar Yusuf

    2007-01-01

    Full Text Available Abstract Whitefly-transmitted geminiviruses (genus Begomovirus are phytopathogens that cause heavy losses to crops worldwide. Efforts to engineer resistance against these viruses are focused mainly on silencing of complementary-sense virus genes involved in virus replication. Here we have targeted a virion-sense gene (AV2 to develop resistance against Tomato leaf curl New Delhi virus, a bipartite begomovirus prevalent throughout the Indian subcontinent. We show that tobacco plants transformed with an antisense construct targeting this gene are resistant to the virus. Following challenged with the virus, transgenic plants remained symptomless, although viral DNA could be detected in some plants by PCR. This is the first report of transgenic resistance against a bipartite begomovirus obtained by targeting a virion-sense gene. The relatively conserved nature of the gene suggests that the technology may be useful to develop broad-spectrum resistance which is required because of the fact that plants are often infected with multiple begomoviruses in the field.

  2. Silencing of the PiAvr3a effector-encoding gene from Phytophthora infestans by transcriptional fusion to a short interspersed element.

    Science.gov (United States)

    Vetukuri, Ramesh R; Tian, Zhendong; Avrova, Anna O; Savenkov, Eugene I; Dixelius, Christina; Whisson, Stephen C

    2011-12-01

    Phytophthora infestans is the notorious oomycete causing late blight of potato and tomato. A large proportion of the P. infestans genome is composed of transposable elements, the activity of which may be controlled by RNA silencing. Accumulation of small RNAs is one of the hallmarks of RNA silencing. Here we demonstrate the presence of small RNAs corresponding to the sequence of a short interspersed retrotransposable element (SINE) suggesting that small RNAs might be involved in silencing of SINEs in P. infestans. This notion was exploited to develop novel tools for gene silencing in P. infestans by engineering transcriptional fusions of the PiAvr3a gene, encoding an RXLR avirulence effector, to the infSINEm retroelement. Transgenic P. infestans lines expressing either 5'-infSINEm::PiAvr3a-3' or 5'-PiAvr3a::SINEm-3' chimeric transcripts initially exhibited partial silencing of PiAvr3a. Over time, PiAvr3a either recovered wild type transcript levels in some lines, or became fully silenced in others. Introduction of an inverted repeat construct was also successful in yielding P. infestans transgenic lines silenced for PiAvr3a. In contrast, constructs expressing antisense or aberrant RNA transcripts failed to initiate silencing of PiAvr3a. Lines exhibiting the most effective silencing of PiAvr3a were either weakly or non-pathogenic on susceptible potato cv. Bintje. This study expands the repertoire of reverse genetics tools available for P. infestans research, and provides insights into a possible mode of variation in effector expression through spread of silencing from adjacent retroelements.

  3. Characterization of the RNA silencing suppression activity of the Ebola virus VP35 protein in plants and mammalian cells.

    Science.gov (United States)

    Zhu, Yali; Cherukuri, Nil Celebi; Jackel, Jamie N; Wu, Zetang; Crary, Monica; Buckley, Kenneth J; Bisaro, David M; Parris, Deborah S

    2012-03-01

    Ebola virus (EBOV) causes a lethal hemorrhagic fever for which there is no approved effective treatment or prevention strategy. EBOV VP35 is a virulence factor that blocks innate antiviral host responses, including the induction of and response to alpha/beta interferon. VP35 is also an RNA silencing suppressor (RSS). By inhibiting microRNA-directed silencing, mammalian virus RSSs have the capacity to alter the cellular environment to benefit replication. A reporter gene containing specific microRNA target sequences was used to demonstrate that prior expression of wild-type VP35 was able to block establishment of microRNA silencing in mammalian cells. In addition, wild-type VP35 C-terminal domain (CTD) protein fusions were shown to bind small interfering RNA (siRNA). Analysis of mutant proteins demonstrated that reporter activity in RSS assays did not correlate with their ability to antagonize double-stranded RNA (dsRNA)-activated protein kinase R (PKR) or bind siRNA. The results suggest that enhanced reporter activity in the presence of VP35 is a composite of nonspecific translational enhancement and silencing suppression. Moreover, most of the specific RSS activity in mammalian cells is RNA binding independent, consistent with VP35's proposed role in sequestering one or more silencing complex proteins. To examine RSS activity in a system without interferon, VP35 was tested in well-characterized plant silencing suppression assays. VP35 was shown to possess potent plant RSS activity, and the activities of mutant proteins correlated strongly, but not exclusively, with RNA binding ability. The results suggest the importance of VP35-protein interactions in blocking silencing in a system (mammalian) that cannot amplify dsRNA.

  4. Virus-induced gene silencing as a tool for functional analyses in the emerging model plant Aquilegia (columbine, Ranunculaceae

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    Kramer Elena M

    2007-04-01

    Full Text Available Abstract Background The lower eudicot genus Aquilegia, commonly known as columbine, is currently the subject of extensive genetic and genomic research aimed at developing this taxon as a new model for the study of ecology and evolution. The ability to perform functional genetic analyses is a critical component of this development process and ultimately has the potential to provide insight into the genetic basis for the evolution of a wide array of traits that differentiate flowering plants. Aquilegia is of particular interest due to both its recent evolutionary history, which involves a rapid adaptive radiation, and its intermediate phylogenetic position between core eudicot (e.g., Arabidopsis and grass (e.g., Oryza model species. Results Here we demonstrate the effective use of a reverse genetic technique, virus-induced gene silencing (VIGS, to study gene function in this emerging model plant. Using Agrobacterium mediated transfer of tobacco rattle virus (TRV based vectors, we induce silencing of PHYTOENE DESATURASE (AqPDS in Aquilegia vulgaris seedlings, and ANTHOCYANIDIN SYNTHASE (AqANS and the B-class floral organ identity gene PISTILLATA in A. vulgaris flowers. For all of these genes, silencing phenotypes are associated with consistent reduction in endogenous transcript levels. In addition, we show that silencing of AqANS has no effect on overall floral morphology and is therefore a suitable marker for the identification of silenced flowers in dual-locus silencing experiments. Conclusion Our results show that TRV-VIGS in Aquilegia vulgaris allows data to be rapidly obtained and can be reproduced with effective survival and silencing rates. Furthermore, this method can successfully be used to evaluate the function of early-acting developmental genes. In the future, data derived from VIGS analyses will be combined with large-scale sequencing and microarray experiments already underway in order to address both recent and ancient evolutionary

  5. Composite potato plants with transgenic roots on non-transgenic shoots: a model system for studying gene silencing in roots

    DEFF Research Database (Denmark)

    Horn, Patricia; Santala, Johanna; Nielsen, Steen Lykke;

    2014-01-01

    Composite plants, with transgenic roots on a non-transgenic shoot, can be obtained by shoot explant transformation with Agrobacterium rhizogenes. The aim of this study was to generate composite potato plants (Solanum tuberosum) to be used as a model system in future studies on root...... of composite potato plants expressed significantly higher amounts of β-glucuronidase (GUS) than the roots of a GUS-transgenic potato line event. Silencing of the uidA transgene (GUS) was tested by inducing roots on the GUS-transgenic cv. Albatros event with strains of A. rhizogenes over-expressing either......-mediated silencing (co-suppression) was not functional in roots. The results suggest that composite plants offer a useful experimental system for potato research, which has gained little previous attention....

  6. RNA-mediated gene silencing signals are not graft transmissible from the rootstock to the scion in greenhouse-grown apple plants Malus sp.

    Science.gov (United States)

    Flachowsky, Henryk; Tränkner, Conny; Szankowski, Iris; Waidmann, Sascha; Hanke, Magda-Viola; Treutter, Dieter; Fischer, Thilo C

    2012-01-01

    RNA silencing describes the sequence specific degradation of RNA targets. Silencing is a non-cell autonomous event that is graft transmissible in different plant species. The present study is the first report on systemic acquired dsRNA-mediated gene silencing of transgenic and endogenous gene sequences in a woody plant like apple. Transgenic apple plants overexpressing a hairpin gene construct of the gusA reporter gene were produced. These plants were used as rootstocks and grafted with scions of the gusA overexpressing transgenic apple clone T355. After grafting, we observed a reduction of the gusA gene expression in T355 scions in vitro, but not in T355 scions grown in the greenhouse. Similar results were obtained after silencing of the endogenous Mdans gene in apple that is responsible for anthocyanin biosynthesis. Subsequently, we performed grafting experiments with Mdans silenced rootstocks and red leaf scions of TNR31-35 in order to evaluate graft transmitted silencing of the endogenous Mdans. The results obtained suggested a graft transmission of silencing signals in in vitro shoots. In contrast, no graft transmission of dsRNA-mediated gene silencing signals was detectable in greenhouse-grown plants and in plants grown in an insect protection tent.

  7. Expression of geminiviral AC2 RNA silencing suppressor changes sugar and jasmonate responsive gene expression in transgenic tobacco plants

    Directory of Open Access Journals (Sweden)

    Soitamo Arto J

    2012-11-01

    Full Text Available Abstract Background RNA-silencing is a conserved gene regulation and surveillance machinery, which in plants, is also used as major defence mechanism against viruses. Various virus-specific dsRNA structures are recognized by the silencing machinery leading to degradation of the viral RNAs or, as in case of begomoviruses, to methylation of their DNA genomes. Viruses produce specific RNA silencing suppressor (RSS proteins to prevent these host defence mechanisms, and as these interfere with the silencing machinery they also disturb the endogenous silencing reactions. In this paper, we describe how expression of AC2 RSS, derived from African cassava mosaic geminivirus changes transcription profile in tobacco (Nicotiana tabacum leaves and in flowers. Results Expression of AC2 RSS in transgenic tobacco plants induced clear phenotypic changes both in leaves and in flowers. Transcriptomes of these plants were strongly altered, with total of 1118 and 251 differentially expressed genes in leaves and flowers, respectively. The three most up-regulated transcript groups were related to stress, cell wall modifications and signalling, whereas the three most down-regulated groups were related to translation, photosynthesis and transcription. It appears that many of the gene expression alterations appeared to be related to enhanced biosynthesis of jasmonate and ethylene, and consequent enhancement of the genes and pathways that are regulated by these hormones, or to the retrograde signalling caused by the reduced photosynthetic activity and sugar metabolism. Comparison of these results to a previous transcriptional profiling of HC-Pro RSS-expressing plants revealed that some of same genes were induced by both RSSs, but their expression levels were typically higher in AC2 than in HC-Pro RSS expressing plants. All in all, a large number of transcript alterations were found to be specific to each of the RSS expressing transgenic plants. Conclusions AC2 RSS in

  8. Expression of geminiviral AC2 RNA silencing suppressor changes sugar and jasmonate responsive gene expression in transgenic tobacco plants.

    Science.gov (United States)

    Soitamo, Arto J; Jada, Balaji; Lehto, Kirsi

    2012-11-07

    RNA-silencing is a conserved gene regulation and surveillance machinery, which in plants, is also used as major defence mechanism against viruses. Various virus-specific dsRNA structures are recognized by the silencing machinery leading to degradation of the viral RNAs or, as in case of begomoviruses, to methylation of their DNA genomes. Viruses produce specific RNA silencing suppressor (RSS) proteins to prevent these host defence mechanisms, and as these interfere with the silencing machinery they also disturb the endogenous silencing reactions. In this paper, we describe how expression of AC2 RSS, derived from African cassava mosaic geminivirus changes transcription profile in tobacco (Nicotiana tabacum) leaves and in flowers. Expression of AC2 RSS in transgenic tobacco plants induced clear phenotypic changes both in leaves and in flowers. Transcriptomes of these plants were strongly altered, with total of 1118 and 251 differentially expressed genes in leaves and flowers, respectively. The three most up-regulated transcript groups were related to stress, cell wall modifications and signalling, whereas the three most down-regulated groups were related to translation, photosynthesis and transcription. It appears that many of the gene expression alterations appeared to be related to enhanced biosynthesis of jasmonate and ethylene, and consequent enhancement of the genes and pathways that are regulated by these hormones, or to the retrograde signalling caused by the reduced photosynthetic activity and sugar metabolism. Comparison of these results to a previous transcriptional profiling of HC-Pro RSS-expressing plants revealed that some of same genes were induced by both RSSs, but their expression levels were typically higher in AC2 than in HC-Pro RSS expressing plants. All in all, a large number of transcript alterations were found to be specific to each of the RSS expressing transgenic plants. AC2 RSS in transgenic tobacco plants interferes with the silencing

  9. Epitope-tagged protein-based artificial miRNA screens for optimized gene silencing in plants.

    Science.gov (United States)

    Li, Jian-Feng; Zhang, Dandan; Sheen, Jen

    2014-04-01

    Artificial miRNA (amiRNA) technology offers highly specific gene silencing in diverse plant species. The principal challenge in amiRNA application is to select potent amiRNAs from hundreds of bioinformatically designed candidates to enable maximal target gene silencing at the protein level. To address this issue, we developed the epitope-tagged protein-based amiRNA (ETPamir) screens, in which single or multiple potential target genes encoding epitope-tagged proteins are constitutively or inducibly coexpressed with individual amiRNA candidates in plant protoplasts. Accumulation of tagged proteins, detected by immunoblotting with commercial tag antibodies, inversely and quantitatively reflects amiRNA efficacy in vivo. The core procedure, from protoplast isolation to identification of optimal amiRNA, can be completed in 2-3 d. The ETPamir screens circumvent the limited availability of plant antibodies and the complexity of plant amiRNA silencing at target mRNA and/or protein levels. The method can be extended to verify predicted target genes for endogenous plant miRNAs.

  10. Heterologous RNA-silencing suppressors from both plant- and animal-infecting viruses support plum pox virus infection.

    Science.gov (United States)

    Maliogka, Varvara I; Calvo, María; Carbonell, Alberto; García, Juan Antonio; Valli, Adrian

    2012-07-01

    HCPro, the RNA-silencing suppressor (RSS) of viruses belonging to the genus Potyvirus in the family Potyviridae, is a multifunctional protein presumably involved in all essential steps of the viral infection cycle. Recent studies have shown that plum pox potyvirus (PPV) HCPro can be replaced successfully by cucumber vein yellowing ipomovirus P1b, a sequence-unrelated RSS from a virus of the same family. In order to gain insight into the requirement of a particular RSS to establish a successful potyviral infection, we tested the ability of different heterologous RSSs from both plant- and animal-infecting viruses to substitute for HCPro. Making use of engineered PPV chimeras, we show that PPV HCPro can be replaced functionally by some, but not all, unrelated RSSs, including the NS1 protein of the mammal-infecting influenza A virus. Interestingly, the capacity of a particular RSS to replace HCPro does not correlate strictly with its RNA silencing-suppression strength. Altogether, our results suggest that not all suppression strategies are equally suitable for efficient escape of PPV from the RNA-silencing machinery. The approach followed here, based on using PPV chimeras in which an under-consideration RSS substitutes for HCPro, could further help to study the function of diverse RSSs in a 'highly sensitive' RNA-silencing context, such as that taking place in plant cells during the process of a viral infection.

  11. The NS3 protein of Rice hoja blanca tenuivirus suppresses RNA silencing in plant and insect hosts by efficiently binding both siRNAs and miRNAs

    NARCIS (Netherlands)

    Hemmes, J.C.; Lakatos, L.; Goldbach, R.W.; Burgyan, J.; Prins, M.W.

    2007-01-01

    RNA silencing plays a key role in antiviral defense as well as in developmental processes in plants and insects. Negative strand RNA viruses such as the plant virus Rice hoja blanca tenuivirus (RHBV) replicate in plants and in their insect transmission vector. Like most plant-infecting viruses, RHBV

  12. The NS3 protein of Rice hoja blanca tenuivirus suppresses RNA silencing in plant and insect hosts by efficiently binding both siRNAs and miRNAs

    NARCIS (Netherlands)

    Hemmes, J.C.; Lakatos, L.; Goldbach, R.W.; Burgyan, J.; Prins, M.W.

    2007-01-01

    RNA silencing plays a key role in antiviral defense as well as in developmental processes in plants and insects. Negative strand RNA viruses such as the plant virus Rice hoja blanca tenuivirus (RHBV) replicate in plants and in their insect transmission vector. Like most plant-infecting viruses, RHBV

  13. Is Impatiens balsamina a qualitative short-day plant?

    Directory of Open Access Journals (Sweden)

    Elżbieta Teske

    2014-01-01

    Full Text Available Impatiens balsamina which, in literature on the physiology of flowering, is assigned to qualitative short-day plants, flowers under Polish climatic conditions from June until September. It flowers, therefore. during the period of the longest day. The photoperiodic responses of I. balsamina plants raised from seeds obtained from botanical gardens located within the range of 23 -65° N. lat. were studied. The experiment revealed marked differences in the photoperiodic responses within the species. Qualitative short-day plants, quantitative short-day plants and day-neutral plants were found in the studied material. An evident correlation was found between the place of origin of the studied seeds and the photoperiodic sensitivity of the plants raised from them.

  14. A strategy for screening an inhibitor of viral silencing suppressors, which attenuates symptom development of plant viruses.

    Science.gov (United States)

    Shimura, Hanako; Fukagawa, Takako; Meguro, Ayano; Yamada, Hirokazu; Oh-Hira, Mahito; Sano, Shinsuke; Masuta, Chikara

    2008-12-10

    To find out whether we can control plant virus diseases by blocking viral RNA silencing suppressors (RSSs), we developed a strategy to screen inhibitors that block the association of RSSs with siRNAs using a surface plasmon resonance assay. The screened chemicals were tested in competition with RSSs for binding to siRNAs using a mobility shift assay. We then confirmed that tested chemicals actually inhibited the RSS activity in vivo using a protoplast assay which was developed for this purpose. This entire system can be adapted to screening inhibitors of not only plant viruses but also some animal viruses possessing RSSs.

  15. Solanum venturii, a suitable model system for virus-induced gene silencing studies in potato reveals StMKK6 as an important player in plant immunity

    NARCIS (Netherlands)

    Dobnik, David; Lazar, Ana; Stare, Tjaša; Gruden, Kristina; Vleeshouwers, Vivianne G.A.A.; Žel, Jana

    2016-01-01

    Background: Virus-induced gene silencing (VIGS) is an optimal tool for functional analysis of genes in plants, as the viral vector spreads throughout the plant and causes reduced expression of selected gene over the whole plant. Potato (Solanum tuberosum) is one of the most important food crops,

  16. Artificial MicroRNA-Based Specific Gene Silencing of Grain Hardness Genes in Polyploid Cereals Appeared to Be Not Stable Over Transgenic Plant Generations

    Science.gov (United States)

    Gasparis, Sebastian; Kała, Maciej; Przyborowski, Mateusz; Orczyk, Waclaw; Nadolska-Orczyk, Anna

    2017-01-01

    Gene silencing by RNA interference is a particularly important tool in the study of gene function in polyploid cereal species for which the collections of natural or induced mutants are very limited. Previously we have been testing small interfering RNA-based approach of gene silencing in wheat and triticale. In this research, artificial microRNAs (amiRs) were studied in the same species and the same target genes to compare effectiveness of both gene silencing pathways. amiR cassettes were designed to silence Puroindoline a (Pina) and Puroindoline b (Pinb) hardness genes in wheat and their orthologues Secaloindoline a (Sina) and Secaloindoline b (Sinb) genes in triticale. Each of the two cassettes contained 21 nt microRNA (miR) precursor derived from conserved regions of Pina/Sina or Pinb/Sinb genes, respectively. Transgenic plants were obtained with high efficiency in two cultivars of wheat and one cultivar of triticale after using the Pinb-derived amiR vector for silencing of Pinb or Sinb, respectively. Lack of transgenic plants in wheat or very low transformation efficiency in triticale was observed using the Pina-derived amiR cassette, despite large numbers of embryos attempted. Silencing of Pinb in wheat and Sinb in triticale was highly efficient in the T1 generation. The transcript level of Pinb in wheat was reduced up to 92% and Sinb in triticale was reduced up to 98%. Moreover, intended silencing of Pinb/Sinb with Pinb-derived amiR cassette was highly correlated with simultaneous silencing of Pina/Sina in the same transgenic plants. High downregulation of Pinb/Pina genes in T1 plants of wheat and Sinb/Sina genes in T1 plants of triticale was associated with strong expression of Pinb-derived amiR. Silencing of the target genes correlated with increased grain hardness in both species. Total protein content in the grains of transgenic wheat was significantly lower. Although, the Pinb-derived amiR cassette was stably inherited in the T2 generation of wheat and

  17. Plant community controls on short-term ecosystem nitrogen retention.

    Science.gov (United States)

    de Vries, Franciska T; Bardgett, Richard D

    2016-05-01

    Retention of nitrogen (N) is a critical ecosystem function, especially in the face of widespread anthropogenic N enrichment; however, our understanding of the mechanisms involved is limited. Here, we tested under glasshouse conditions how plant community attributes, including variations in the dominance, diversity and range of plant functional traits, influence N uptake and retention in temperate grassland. We added a pulse of (15) N to grassland plant communities assembled to represent a range of community-weighted mean plant traits, trait functional diversity and divergence, and species richness, and measured plant and microbial uptake of (15) N, and leaching losses of (15) N, as a short-term test of N retention in the plant-soil system. Root biomass, herb abundance and dominant plant traits were the main determinants of N retention in the plant-soil system: greater root biomass and herb abundance, and lower root tissue density, increased plant (15) N uptake, while higher specific leaf area and root tissue density increased microbial (15) N uptake. Our results provide novel, mechanistic insight into the short-term fate of N in the plant-soil system, and show that dominant plant traits, rather than trait functional diversity, control the fate of added N in the plant-soil system.

  18. Short Hairpin RNA Silencing of PHD-2 Improves Neovascularization and Functional Outcomes in Diabetic Wounds and Ischemic Limbs.

    Directory of Open Access Journals (Sweden)

    Kevin J Paik

    Full Text Available The transcription factor hypoxia-inducible factor 1-alpha (HIF-1α is responsible for the downstream expression of over 60 genes that regulate cell survival and metabolism in hypoxic conditions as well as those that enhance angiogenesis to alleviate hypoxia. However, under normoxic conditions, HIF-1α is hydroxylated by prolyl hydroxylase 2, and subsequently degraded, with a biological half-life of less than five minutes. Here we investigated the therapeutic potential of inhibiting HIF-1α degradation through short hairpin RNA silencing of PHD-2 in the setting of diabetic wounds and limb ischemia. Treatment of diabetic mouse fibroblasts with shPHD-2 in vitro resulted in decreased levels of PHD-2 transcript demonstrated by qRT-PCR, higher levels of HIF-1α as measured by western blot, and higher expression of the downstream angiogenic genes SDF-1 and VEGFα, as measured by qRT-PCR. In vivo, shPHD-2 accelerated healing of full thickness excisional wounds in diabetic mice compared to shScr control, (14.33 ± 0.45 days vs. 19 ± 0.33 days and was associated with an increased vascular density. Delivery of shPHD-2 also resulted in improved perfusion of ischemic hind limbs compared to shScr, prevention of distal digit tip necrosis, and increased survival of muscle tissue. Knockdown of PHD-2 through shRNA treatment has the potential to stimulate angiogenesis through overexpression of HIF-1α and upregulation of pro-angiogenic genes downstream of HIF-1α, and may represent a viable, non-viral approach to gene therapy for ischemia related applications.

  19. Salicylic acid and gentisic acid induce RNA silencing-related genes and plant resistance to RNA pathogens.

    Science.gov (United States)

    Campos, Laura; Granell, Pablo; Tárraga, Susana; López-Gresa, Pilar; Conejero, Vicente; Bellés, José María; Rodrigo, Ismael; Lisón, Purificación

    2014-04-01

    We have observed that treatments with salicylic acid (SA) or gentisic acid (GA) induced resistance to RNA pathogens such as ToMV and CEVd in tomato and Gynura auriantiaca, respectively. Accumulation of SA and GA has been found to occur in plants infected by these pathogens, thus pointing out a possible defence role of both molecules. To study the molecular basis of the observed induced resistance to RNA pathogens the induction of silencing-related genes by SA and GA was considered. For that purpose, we searched for tomato genes which were orthologous to those described in Arabidopsis thaliana, such as AtDCL1, AtDCL2, AtDCL4, AtRDR1, AtRDR2 and AtRDR6, and we tracked their induction in tomato along virus and viroid infections. We observed that CEVd significantly induced all these genes in tomato, with the exception of ToRDR6, being the induction of ToDCL4 the most outstanding. Regarding the ToMV asymptomatic infection, with the exception of ToRDR2, we observed a significant induction of all the indicated silencing-related genes, being ToDCL2 the most induced gene. Subsequently, we analyzed their transcriptional activation by SA and at the time when ToMV was inoculated on plants. ToDCL2, ToRDR1 and ToRDR2 were significantly induced by both SA and GA, whereas ToDCL1 was only induced by SA. Such an induction resulted more effective by SA treatment, which is in agreement with the stronger SA-induced resistance observed. Our results suggest that the observed delay in the RNA pathogen accumulation could be due to the pre-induction of RNA silencing-related genes by SA or GA.

  20. Suppression of RNA silencing by a plant DNA virus satellite requires a host calmodulin-like protein to repress RDR6 expression.

    Directory of Open Access Journals (Sweden)

    Fangfang Li

    2014-02-01

    Full Text Available In plants, RNA silencing plays a key role in antiviral defense. To counteract host defense, plant viruses encode viral suppressors of RNA silencing (VSRs that target different effector molecules in the RNA silencing pathway. Evidence has shown that plants also encode endogenous suppressors of RNA silencing (ESRs that function in proper regulation of RNA silencing. The possibility that these cellular proteins can be subverted by viruses to thwart host defense is intriguing but has not been fully explored. Here we report that the Nicotiana benthamiana calmodulin-like protein Nbrgs-CaM is required for the functions of the VSR βC1, the sole protein encoded by the DNA satellite associated with the geminivirus Tomato yellow leaf curl China virus (TYLCCNV. Nbrgs-CaM expression is up-regulated by the βC1. Transgenic plants over-expressing Nbrgs-CaM displayed developmental abnormities reminiscent of βC1-associated morphological alterations. Nbrgs-CaM suppressed RNA silencing in an Agrobacterium infiltration assay and, when over-expressed, blocked TYLCCNV-induced gene silencing. Genetic evidence showed that Nbrgs-CaM mediated the βC1 functions in silencing suppression and symptom modulation, and was required for efficient virus infection. Moreover, the tobacco and tomato orthologs of Nbrgs-CaM also possessed ESR activity, and were induced by betasatellite to promote virus infection in these Solanaceae hosts. We further demonstrated that βC1-induced Nbrgs-CaM suppressed the production of secondary siRNAs, likely through repressing RNA-DEPENDENT RNA POLYMERASE 6 (RDR6 expression. RDR6-deficient N. benthamiana plants were defective in antiviral response and were hypersensitive to TYLCCNV infection. More significantly, TYLCCNV could overcome host range restrictions to infect Arabidopsis thaliana when the plants carried a RDR6 mutation. These findings demonstrate a distinct mechanism of VSR for suppressing PTGS through usurpation of a host ESR, and

  1. Cytoplasmic and nuclear quality control and turnover of single-stranded RNA modulate post-transcriptional gene silencing in plants

    Science.gov (United States)

    Moreno, Ana Beatriz; Martínez de Alba, Angel Emilio; Bardou, Florian; Crespi, Martin D.; Vaucheret, Hervé; Maizel, Alexis; Mallory, Allison C.

    2013-01-01

    Eukaryotic RNA quality control (RQC) uses both endonucleolytic and exonucleolytic degradation to eliminate dysfunctional RNAs. In addition, endogenous and exogenous RNAs are degraded through post-transcriptional gene silencing (PTGS), which is triggered by the production of double-stranded (ds)RNAs and proceeds through short-interfering (si)RNA-directed ARGONAUTE-mediated endonucleolytic cleavage. Compromising cytoplasmic or nuclear 5′–3′ exoribonuclease function enhances sense-transgene (S)-PTGS in Arabidopsis, suggesting that these pathways compete for similar RNA substrates. Here, we show that impairing nonsense-mediated decay, deadenylation or exosome activity enhanced S-PTGS, which requires host RNA-dependent RNA polymerase 6 (RDR6/SGS2/SDE1) and SUPPRESSOR OF GENE SILENCING 3 (SGS3) for the transformation of single-stranded RNA into dsRNA to trigger PTGS. However, these RQC mutations had no effect on inverted-repeat–PTGS, which directly produces hairpin dsRNA through transcription. Moreover, we show that these RQC factors are nuclear and cytoplasmic and are found in two RNA degradation foci in the cytoplasm: siRNA-bodies and processing-bodies. We propose a model of single-stranded RNA tug-of-war between RQC and S-PTGS that ensures the correct partitioning of RNA substrates among these RNA degradation pathways. PMID:23482394

  2. Gene silencing: concepts, applications, and perspectives in woody plants Silenciamento gênico: conceitos, aplicações e perspectivas em plantas lenhosas

    Directory of Open Access Journals (Sweden)

    Amancio José de Souza

    2007-12-01

    Full Text Available RNA interference, transcriptional gene silencing, virus induced gene silencing, and micro RNAs comprise a series of mechanisms capable of suppressing gene expression in plants. These mechanisms reveal similar biochemical pathways and appear to be related in several levels. The ability to manipulate gene silencing has produced transgenic plants able to switch off endogenous genes and invading nucleic acids. This powerful biotechnological tool has provided plant breeders and researchers with great opportunity to accelerate breeding programs and developmental studies in woody plants. This research work reports on gene silencing in woody plants, and discuss applications and future perspectives.RNA de interferência, silenciamento gênico transcricional, silenciamento gênico induzido por vírus e micro RNAs compõem uma série de mecanismos capazes de suprimir a expressão gênica em plantas. Estes mecanismos revelaram rotas metabólicas parecidas e interagem em vários níveis. A capacidade de manipular técnicas de silenciamento gênico tem produzido plantas transgênicas capazes de suprimir a expressão de genes endógenos e ácidos nucléicos invasores. Esta poderosa ferramenta biotecnológica tem ofertado a possibilidade de acelerar programas de melhoramento e pesquisas em desenvolvimento de plantas lenhosas. Este trabalho visa revisar pesquisas de silenciamento gênico em plantas lenhosas e discutir aplicações e rumos futuros.

  3. Silence multiple

    DEFF Research Database (Denmark)

    Søndergaard, Katia Dupret

    The article highlights the importance of silences in the processes of innovation in organizations, and the claim is that silence and the absence of talk distribute authority, responsibility and decisions. The act of silencing is conceptualised as a central “configurating actor”. Using an Actor-Network...... it an important analytical element in understanding organizing and organizations....

  4. Improved silencing suppression and enhanced heterologous protein expression are achieved using an engineered viral helper component proteinase.

    Science.gov (United States)

    Haikonen, T; Rajamäki, M-L; Valkonen, J P T

    2013-11-01

    RNA silencing limits transient expression of heterologous proteins in plants. Co-expression of viral silencing suppressor proteins can increase and prolong protein expression, but highly efficient silencing suppressors may stress plant tissue and be detrimental to protein yields. Little is known whether silencing suppression could be improved without harm to plant tissues. This study reports development of enhanced silencing suppressors by engineering the helper component proteinase (HCpro) of Potato virus A (PVA). Mutations were introduced to a short region of HCpro (positions 330-335 in PVA HCpro), which is hypervariable among potyviruses. Three out of the four HCpro mutants suppressed RNA silencing more efficiently and sustained expression of co-expressed jellyfish green fluorescent protein for a longer time than wild-type HCpro in agroinfiltrated leaves of Nicotiana benthamiana. Leaf tissues remained healthy-looking without any visible signs of stress.

  5. Short-term tests of estrogenic potential of plant stanols and plant stanol esters

    NARCIS (Netherlands)

    Turnbull, D.; Frankos, V.H.; Leeman, W.R.; Jonker, D.

    1999-01-01

    To test for potential estrogenic activity of plant stanols and plant stanol esters, two short-term tests were performed. These were the E-screen test, which measures a substance's ability to induce proliferation of estrogen-responsive human breast adenocarcinoma (MCF-7) cells in culture, and an in

  6. Short-term tests of estrogenic potential of plant stanols and plant stanol esters

    NARCIS (Netherlands)

    Turnbull, D.; Frankos, V.H.; Leeman, W.R.; Jonker, D.

    1999-01-01

    To test for potential estrogenic activity of plant stanols and plant stanol esters, two short-term tests were performed. These were the E-screen test, which measures a substance's ability to induce proliferation of estrogen-responsive human breast adenocarcinoma (MCF-7) cells in culture, and an in v

  7. Short-term tests of estrogenic potential of plant stanols and plant stanol esters

    NARCIS (Netherlands)

    Turnbull, D.; Frankos, V.H.; Leeman, W.R.; Jonker, D.

    1999-01-01

    To test for potential estrogenic activity of plant stanols and plant stanol esters, two short-term tests were performed. These were the E-screen test, which measures a substance's ability to induce proliferation of estrogen-responsive human breast adenocarcinoma (MCF-7) cells in culture, and an in v

  8. Silence multiple

    DEFF Research Database (Denmark)

    Søndergaard, Katia Dupret

    The article highlights the importance of silences in the processes of innovation in organizations, and the claim is that silence and the absence of talk distribute authority, responsibility and decisions. The act of silencing is conceptualised as a central “configurating actor”. Using an Actor......-Network Theoretical approach to organization studies silence is conceptualised as both a means and an effect of innovative efforts. It is a way of ordering practices. Thus silencing is thought of as a central potential change agent both in composing a kind of specific organizational collectivity and in composing new...... working practices more generally. In line with the approach to destabilise the mundane, invisible and taken-for-granted aspects of innovative efforts in organisations (crucial for ANT and foucauldian post-structuralism more broadly), this article suggests to non-silence the silence and make...

  9. Gene silencing of NR2B-containing NMDA receptor by intrathecal injection of short hairpin RNA reduces formalin-induced nociception in C57BL/6 mouse.

    Science.gov (United States)

    Zhang, Rao-Xiang; Yan, Xue-Bin; Gu, Yong-Hong; Huang, Dong; Gan, Li; Han, Rui; Huang, Li-Hua

    2013-09-01

    Spinal NR2B-containing N-methyl-D-aspartate receptors (NR2B) play a critical role in the formation of central sensitization and persistent pain. Previous studies show that gene silencing of the spinal NR2B subunit by small interfering RNA (siRNA) could alleviate nociception in animals. The siRNA is a 19- to 23-nt RNA duplex, which can be synthesized in vitro or derived from short hairpin RNAs (shRNAs). In the present study, we investigated whether intrathecal injection of shRNAs targeting NR2B (GRIN2B shRNA) could affect nociception on formalin-induced pain in mice. Our results showed that intrathecal injection of GRIN2B shRNA could decrease NR2B mRNA and protein expression levels and hence effectively relieve formalin-induced nociception in mice, suggesting that intrathecal delivery of GRIN2B shRNA can be an efficient way to silence the target gene and provide new insights into the treatment of chronic pain.

  10. Silencing of meiosis-critical genes for engineering male sterility in plants

    Science.gov (United States)

    Engineering sterile traits in plants through the tissue-specific expression of a cytotoxic gene provides an effective way for containing transgene flow; however, the microbial origin of cytotoxic genes has raised concerns. In an attempt to develop a safe alternative, we have chosen the meiosis-crit...

  11. Algorithms for short-term production planning of cogeneration plants

    Energy Technology Data Exchange (ETDEWEB)

    Dotzauer, E.

    1998-03-01

    A cogeneration plant, feeding its output water into a district-heating network, may include several types of energy producing units. The most important being the Co-generation unit, which produces both heat and electricity. Most plants also have a Heat water storage. Finding the optimal production of both heat and electricity and the optimal use of the storage is a challenging mixed integer nonlinear optimization problem. The calculations may be divided into two sub-problems. The unit commitment problem is the problem to determine when a unit should be producing (on) or not (off). To solve the economic dispatch problem is to find the optimal production plan given which units are producing in each time interval. Together the solution of these two problems form the solution of the short-term production-planning problem. In this thesis a general approach for the mathematical modeling of a co-generation plant is presented. The model objective function is nonlinear, with nonlinear constraints. Internal plant temperatures, mass flows, storage losses, minimal up and down times and time dependent start-up costs are considered. The demand for heat, the forward temperature from the plant, the return temperature to the plant and the price of electricity are assumed to be known quantities. The net electric power produced is sold for the estimated current market price of electricity. The unit commitment problem is solved with an algorithm based on Lagrangian relaxation. The dual search direction is computed by the sub gradient method and the step length by the Polyak rule II. A heuristic method for the generation of primal feasible solutions is developed. The economic dispatch problem is solved using a combination of dynamic programming and general-purpose solvers. Algorithms to find starting values for the problem are developed. The model and the algorithms are implemented in MATLAB, illustrated with numerical examples and analyzed with numerical tests

  12. RNA Interference (RNAi) Induced Gene Silencing: A Promising Approach of Hi-Tech Plant Breeding.

    Science.gov (United States)

    Younis, Adnan; Siddique, Muhammad Irfan; Kim, Chang-Kil; Lim, Ki-Byung

    2014-01-01

    RNA interference (RNAi) is a promising gene regulatory approach in functional genomics that has significant impact on crop improvement which permits down-regulation in gene expression with greater precise manner without affecting the expression of other genes. RNAi mechanism is expedited by small molecules of interfering RNA to suppress a gene of interest effectively. RNAi has also been exploited in plants for resistance against pathogens, insect/pest, nematodes, and virus that cause significant economic losses. Keeping beside the significance in the genome integrity maintenance as well as growth and development, RNAi induced gene syntheses are vital in plant stress management. Modifying the genes by the interference of small RNAs is one of the ways through which plants react to the environmental stresses. Hence, investigating the role of small RNAs in regulating gene expression assists the researchers to explore the potentiality of small RNAs in abiotic and biotic stress management. This novel approach opens new avenues for crop improvement by developing disease resistant, abiotic or biotic stress tolerant, and high yielding elite varieties.

  13. UV-C-Induced alleviation of transcriptional gene silencing through plant–plant communication: Key roles of jasmonic acid and salicylic acid pathways

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wei; Wang, Ting [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Hefei, Anhui, 230031 (China); Xu, Shaoxin [School of physics and materials science, Anhui University, Hefei, Anhui, 230601 (China); Li, Fanghua; Deng, Chenguang; Wu, Lijun; Wu, Yuejin [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Hefei, Anhui, 230031 (China); Bian, Po, E-mail: bianpo@ipp.ac.cn [Key Laboratory of Ion Beam Bio-engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, P.O. Box 1138, Hefei, Anhui, 230031 (China)

    2016-08-15

    Highlights: • Transcriptional gene silencing (TGS) in plants can be epigenetically alleviated by volatile signals from UV-C- irradiated neighboring plants. • Alleviation of TGS can be induced by UV-C irradiation through plant–plant–plant communication. • JA and SA signals take part in interplant communication for alleviation of TGS. - Abstract: Plant stress responses at the epigenetic level are expected to allow more permanent changes of gene expression and potentially long-term adaptation. While it has been reported that plants subjected to adverse environments initiate various stress responses in their neighboring plants, little is known regarding epigenetic responses to external stresses mediated by plant–plant communication. In this study, we show that DNA repetitive elements of Arabidopsis thaliana, whose expression is inhibited epigenetically by transcriptional gene silencing (TGS) mechanism, are activated by UV-C irradiation through airborne plant–plant and plant–plant–plant communications, accompanied by DNA demethylation at CHH sites. Moreover, the TGS is alleviated by direct treatments with exogenous methyl jasmonate (MeJA) and methyl salicylate (MeSA). Further, the plant–plant and plant–plant–plant communications are blocked by mutations in the biosynthesis or signaling of jasmonic acid (JA) or salicylic acid (SA), indicating that JA and SA pathways are involved in the interplant communication for epigenetic responses. For the plant–plant–plant communication, stress cues are relayed to the last set of receiver plants by promoting the production of JA and SA signals in relaying plants, which exhibit upregulated expression of genes for JA and SA biosynthesis and enhanced emanation of MeJA and MeSA.

  14. The RNA silencing enzyme RNA polymerase v is required for plant immunity.

    Directory of Open Access Journals (Sweden)

    Ana López

    2011-12-01

    Full Text Available RNA-directed DNA methylation (RdDM is an epigenetic control mechanism driven by small interfering RNAs (siRNAs that influence gene function. In plants, little is known of the involvement of the RdDM pathway in regulating traits related to immune responses. In a genetic screen designed to reveal factors regulating immunity in Arabidopsis thaliana, we identified NRPD2 as the OVEREXPRESSOR OF CATIONIC PEROXIDASE 1 (OCP1. NRPD2 encodes the second largest subunit of the plant-specific RNA Polymerases IV and V (Pol IV and Pol V, which are crucial for the RdDM pathway. The ocp1 and nrpd2 mutants showed increases in disease susceptibility when confronted with the necrotrophic fungal pathogens Botrytis cinerea and Plectosphaerella cucumerina. Studies were extended to other mutants affected in different steps of the RdDM pathway, such as nrpd1, nrpe1, ago4, drd1, rdr2, and drm1drm2 mutants. Our results indicate that all the mutants studied, with the exception of nrpd1, phenocopy the nrpd2 mutants; and they suggest that, while Pol V complex is required for plant immunity, Pol IV appears dispensable. Moreover, Pol V defective mutants, but not Pol IV mutants, show enhanced disease resistance towards the bacterial pathogen Pseudomonas syringae DC3000. Interestingly, salicylic acid (SA-mediated defenses effective against PsDC3000 are enhanced in Pol V defective mutants, whereas jasmonic acid (JA-mediated defenses that protect against fungi are reduced. Chromatin immunoprecipitation analysis revealed that, through differential histone modifications, SA-related defense genes are poised for enhanced activation in Pol V defective mutants and provide clues for understanding the regulation of gene priming during defense. Our results highlight the importance of epigenetic control as an additional layer of complexity in the regulation of plant immunity and point towards multiple components of the RdDM pathway being involved in plant immunity based on genetic evidence

  15. Use of the modified viral satellite DNA vector to silence mineral nutrition-related genes in plants: silencing of the tomato ferric chelate reductase gene, FRO1, as an example

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Virus-induced gene silencing (VIGS) is potentially an attractive reverse-genetics tool for studies of plant gene function, but whether it is effective in silencing mineral nutritional-related genes in roots has not been demonstrated. Here we report on an efficient VIGS system that functions in tomato roots using a modified viral satellite DNA (DNAmβ) associated with Tomato yellow leaf curl China virus (TYLCCNV). A cDNA fragment of the ferric chelate reductase gene (FRO1) from tomato was inserted into the DNAmβ vector. Tomato roots agro-inoculated with DNAmβ carrying both a fragment of FRO1 and TYLCCNV used as a helper virus exhibited a significant reduction at the FRO1 mRNA level. As a consequence, ferric chelate reductase activity, as determined by visualization of the pink FeBPDS3 complex was significantly decreased. Our results clearly demonstrated that VIGS system can be employed to investigate gene function associated with plant nutrient uptake in roots.

  16. Use of the modified viral satellite DNA vector to silence mineral nutrition-related genes in plants: silencing of the tomato ferric chelate reductase gene, FRO1, as an example

    Institute of Scientific and Technical Information of China (English)

    HE XiuXia; JIN ChongWei; LI GuiXin; YOU GuangYi; ZHOU XuePing; ZHENG ShaoJian

    2008-01-01

    Virus-induced gene silencing (VIGS) is potentially an attractive reverse-genetics tool for studies of plant gene function, but whether it is effective in silencing mineral nutritional-related genes in roots has not been demonstrated. Here we report on an efficient VIGS system that functions in tomato roots using a modified viral satellite DNA (DNAmβ) associated with Tomato yellow leaf curl China virus (TYLCCNV). A cDNA fragment of the ferric chelate reductase gene (FRO1) from tomato was inserted into the DNAmβ vector. Tomato roots agro-inoculated with DNAmβ carrying both a fragment of FRO1 and TYLCCNV used as a helper virus exhibited a significant reduction at the FRO1 mRNA level. As a consequence, ferric chelate reductase activity, as determined by visualization of the pink FeBPDS3complex was significantly decreased. Our results clearly demonstrated that VIGS system can be employed to investigate gene function associated with plant nutrient uptake in roots.

  17. Silencing tissue inhibitors of metalloproteinases (TIMPs) with short interfering RNA reveals a role for TIMP-1 in hepatic stellate cell proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Fowell, Andrew J., E-mail: ajf2@soton.ac.uk [Liver and Pancreas Group, University of Southampton, Division of Infection, Inflammation and Immunity, Southampton General Hospital, Southampton (United Kingdom); Collins, Jane E.; Duncombe, Dale R.; Pickering, Judith A. [Liver and Pancreas Group, University of Southampton, Division of Infection, Inflammation and Immunity, Southampton General Hospital, Southampton (United Kingdom); Rosenberg, William M.C. [Centre for Hepatology, Division of Medicine, University College London, London (United Kingdom); Benyon, R. Christopher [Liver and Pancreas Group, University of Southampton, Division of Infection, Inflammation and Immunity, Southampton General Hospital, Southampton (United Kingdom)

    2011-04-08

    Research highlights: {yields} Myofibroblastic, activated hepatic stellate cells (HSC) play a pivotal role in the development of liver fibrosis. {yields} We used short interfering RNA (siRNA) to investigate the effects of autocrine TIMP-1 and -2 on HSC proliferation. {yields} Specific silencing of TIMP-1, but not TIMP-2, significantly reduces HSC proliferation and is associated with reduced Akt phosphorylation. {yields} TIMP-1 is localised in part to the HSC nucleus. {yields} TIMP-1 might promote liver fibrosis by means other than its previously described anti-apoptotic effect on HSC. -- Abstract: Myofibroblastic, activated hepatic stellate cells (HSC) play a pivotal role in the development of liver fibrosis through the secretion of fibrillar collagens and the tissue inhibitors of metalloproteinase (TIMP)-1 and -2. TIMPs are believed to promote hepatic fibrosis by inhibiting both matrix degradation and apoptosis of HSC. In other cell types, there is evidence that TIMP-1 has effects on proliferation, however the role of TIMPs in the regulation of HSC proliferation remains unexplored. Therefore, we have used short interfering RNA (siRNA) to investigate the effects of autocrine TIMP-1 and -2 on HSC proliferation. TIMP-1 and -2 siRNA were highly effective, producing peak target protein knockdown compared to negative control siRNA of 92% and 63%, respectively. Specific silencing of TIMP-1, using siRNA, significantly reduced HSC proliferation. TIMP-1 was localised in part to the HSC nucleus and TIMP-1 siRNA resulted in loss of both cytoplasmic and nuclear TIMP-1. Attenuated proliferation was associated with reduced Akt phosphorylation and was partially rescued by addition of recombinant TIMP-1. We have revealed a novel autocrine mitogenic effect of TIMP-1 on HSC, which may involve Akt-dependent and specific nuclear mechanisms of action. We suggest that TIMP-1 might promote liver fibrosis by means other than its previously described anti-apoptotic effect on HSC. Moreover

  18. Plant Mobile Small RNAs

    Science.gov (United States)

    Dunoyer, Patrice; Melnyk, Charles; Molnar, Attila; Slotkin, R. Keith

    2013-01-01

    In plants, RNA silencing is a fundamental regulator of gene expression, heterochromatin formation, suppression of transposable elements, and defense against viruses. The sequence specificity of these processes relies on small noncoding RNA (sRNA) molecules. Although the spreading of RNA silencing across the plant has been recognized for nearly two decades, only recently have sRNAs been formally demonstrated as the mobile silencing signals. Here, we discuss the various types of mobile sRNA molecules, their short- and long-range movement, and their function in recipient cells. PMID:23818501

  19. [Effects of seven RNA silencing suppressors on heterologous expression of green fluorescence protein expression mediated by a plant virus-based system in Nicotiana benthamiana].

    Science.gov (United States)

    Wang, Sheng; Dong, Jie; Cao, Min; Mu, Hongzhen; Ding, Guoping; Zhang, Hong

    2012-11-01

    To test the effects of 7 virus-encoded RNA silencing suppressors (RSSs) for enhancement of a plant virus-based vector system-mediated heterologous expression of green fluorescence protein (GFP) in Nicotiana benthamiana. Seven transient expression vectors for the 7 RSSs were constructed and co-inoculated on the leaves of Nicotiana benthamiana with PVXdt-GFP vector, a novel Potato virus X-based plant expression vector, through agroinfiltration. The protein and mRNA expression levels of the reporter gene GFP in the co-inoculated Nicotiana leaves were examined by Western blotting, ELISA and RT-qPCR to assess the effect of the RSSs for GFP expression enhancement. The 7 RSSs differed in the degree and duration of enhancement of heterologous GFP expression, and the p19 protein of Tomato bushy stunt virus (TBSV) induced the highest expression of GFP. African cassava mosaic virus AC2 protein and Rice yellow mettle virus P1 protein produced no obvious enhancement GFP expression. Transient co-expression of RSSs suppresses host silencing response to allow high-level and long-term expression of heterologous genes in plant, but the optimal RSS has to be identified for each plant virus-based expression vector system.

  20. RNAi silencing of a cytochrome P450 monoxygenase disrupts the ability of a filamentous fungus, Graphium sp., to grow on short-chain gaseous alkanes and ethers.

    Science.gov (United States)

    Trippe, Kristin M; Wolpert, Thomas J; Hyman, Michael R; Ciuffetti, Lynda M

    2014-02-01

    Graphium sp. (ATCC 58400), a filamentous fungus, is one of the few eukaryotes that grows on short-chain alkanes and ethers. In this study, we investigated the genetic underpinnings that enable this fungus to catalyze the first step in the alkane and ether oxidation pathway. A gene, CYP52L1, was identified, cloned and functionally characterized as an alkane-oxidizing cytochrome P450 (GSPALK1). Analysis of CYP52L1 suggests that it is a member of the CYP52 cytochrome P450 family, which is comprised of medium- and long-chain alkane-oxidizing enzymes found in yeasts. However, phylogenetic analysis of GSPALK1 with other CYP52 members suggests they are not closely related. Post-transcriptional ds-RNA-mediated gene silencing of CYP52L1 severely reduced the ability of this fungus to oxidize alkanes and ethers, however, downstream metabolic steps in these pathways were unaffected. Collectively, the results of this study suggest that GSPALK1 is the enzyme that catalyzes the initial oxidation of alkanes and ethers but is not involved in the later steps of alkane or ether metabolism.

  1. P19 of Tomato Bushy Stunt Virus Suppresses RNA Silencing Induced by Short Hairpin RNA in Mammal Cells

    Institute of Scientific and Technical Information of China (English)

    Wei-xian CHEN; Juan CHEN; Zhen-zhen ZHANG; Ai-long HUANG

    2007-01-01

    To counteract the immune system in parasitic hosts, some viruses encode proteins to suppress the RNA interference (RNAi) effect. In this report, we established two RNAi systems to be easily observed with strong and obvious effect. The function of the P19 of tomato bushy stunt virus, which suppresses RNAi in mammal cells, was then studied using these two systems. Short hairpin RNAs targeting green fluorescence protein (pshRNA-GFP) and firefly luciferase (pshRNA-luc) were designed and inserted into a eukaryotic transcriptional vector pTZU6+1, respectively. The shRNA expressing vectors were co-transfected with plasmids containing the target gene with or without P19. The GFP expression level was assayed by fluorescence microscopy, Western blotting and RT-PCR. The luciferase expression level was analyzed by the dual-luciferase assay system. pshRNA designed in this study down-regulated the target gene specifically and efficiently, with a decrease of expression of both genes of about 70%, respectively. When P19 was introduced into the RNAi systems, the expression of both GFP and the luciferase were mostly recovered compared with the control groups. The RNAi systems of GFP and luciferase were constructed successfully, demonstrating that P19 of tomato bushy stunt virus has the ability to counteract the RNAi effect induced by shRNA in mammal cells.

  2. Apoptosis induced by short hairpin RNA-mediated STAT6 gene silencing in human colon cancer cells

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ming-sheng; ZHOU Yun-feng; ZHANG Wen-jie; ZHANG Xiao-lian; PAN Qin; JI Xue-mei; LUO Zhi-guo; WU Jian-ping

    2006-01-01

    Background The relationship between signal transduction and tumors has become one of the foci in cancer research. Signal transducer and activator of the transcription 6 (STAT6) signaling pathway is found to be activated in some cancer cells. But the function of the pathway in cancer cells is unknown. This study was undertaken to investigate the effect of the Stat6 signaling pathway on apoptosis in human colon cancer cells (HT-29 cells) and the possible mechanism of Stat6 by RNA interference techniques.Methods Four eukaryotic expression plasmid vectors of short hairpin RNA (shRNA) specific for the STAT6gene were designed and generated by molecular biological technology. The plasmid vectors were transfected into HT-29 cells by cation liposomes to block the Stat6 signaling pathway. The expressions of STAT6 mRNA and phosph-Stat6 protein were detected by the reverse transcriptase polymerase chain reaction (RT-PCR) method and flow cytometry respectively to screen the most effective shRNA at 72 hours after transfection. The apoptosis condition of the cells in which the expression of the STAT6 gene had been interfered was analyzed by flow cytometry and confocal microscopy. Both mRNA and protein expression of B cell lymphoma-2 (Bcl-2) and Bax were detected by RT-PCR and western blotting.Results Two effective eukaryotic expression plasmid vectors of shRNA specific for the STAT6 gene were generated successfully. One can reduce the expression of the STAT6 gene by 82.4% and the other by 56.8%(P<0.01). The apoptotic rate of colon cancer cells in which STAT6 gene expression had been interfered was significantly higher than that in controlled colon cancer cells (P<0.01). In the cells in which the Stat6 signaling pathway was blocked, the levels of mRNA and protein Bcl-2 were significantly decreased, whereas those of Bax were significantly increased (P<0.01).Conclusions The Stat6 signaling pathway can inhibit apoptosis in human colon cancer cells. The subsequent disorder of

  3. The amylose-free potato mutant as a model plant to study gene expression and gene silencing.

    NARCIS (Netherlands)

    Flipse, E.

    1995-01-01

    In this thesis, gene-expression and gene silencing were examined for Granule Bound Starch Synthase (GBSS) which catalyses the formation of amylose and Branching Enzyme (BE) which catalyses the formation of amylopectin. The (GBSS) deficient, with iodine, red staining amylose-free (amf) potato mutant

  4. Influence of retinoblastoma-related gene silencing on the initiation of DNA replication by African cassava mosaic virus Rep in cells of mature leaves in Nicotiana benthamiana plants

    Directory of Open Access Journals (Sweden)

    Bruce Gareth

    2011-12-01

    Full Text Available Abstract Background Geminiviruses mainly infect terminally differentiated tissues and cells in plants. They need to reprogramme host cellular machinery for DNA replication. This process is thought to be mediated by inactivation of cell-cycle repressor proteins and by induction of host DNA synthesis protein expression through actions of the geminviral replication initiator protein (Rep. Findings Exploiting a Nicotiana benthamiana pOri2 line, which is transformed with a transgene consisting of a direct repeat of the African cassava mosaic virus (ACMV-replication origin (Ori flanking a non-viral DNA region, and virus-induced RNA silencing (VIGS, the impact of host gene expression on replication of the ACMV-derived replicon was investigated. The ACMV Rep trans-replicated the viral episomal replicon in leaves of young but not older pOri2 plants. Upon VIGS-mediated down-regulation of N. benthamiana NbRBR1, the retinoblastoma-related protein gene coding for a negative cell-cycle suppressor, recovered the ability of ACMV Rep for trans DNA replication, whereas the silencing of NbPCNA coding for the sliding clamp of DNA polymerase had no effect. Conclusions These results suggest that the cellular machinery for DNA replication in differentiated tissues of older leaves cannot be reprogrammed by Rep alone but may need other uncharacterised viral and plant factors.

  5. Virus-induced gene silencing in soybean seeds and the emergence stage of soybean plants with Apple latent spherical virus vectors.

    Science.gov (United States)

    Yamagishi, Noriko; Yoshikawa, Nobuyuki

    2009-09-01

    Virus-induced gene silencing (VIGS) has great potential as a reverse-genetics tool in plant genomics. In this study, we examined the potential of VIGS in soybean seeds and the emergence stage of soybean plants using Apple latent spherical virus (ALSV) vectors. Inoculation of an ALSV vector (soyPDS-ALSV) carrying a fragment of the soybean phytoene desaturase (soyPDS) gene into soybean seedlings resulted in a highly uniform photo-bleached phenotype, typical of PDS inhibition, on the upper leaves throughout plant growth. The photo-bleached phenotype was also found on all immature pods, all seed coats, and about 50% embryos of seeds on soybean plants infected with soyPDS-ALSV. Infection with an ALSV vector (soyIFS2-ALSV) having a fragment of soybean isoflavone synthase 2 (soyIFS2) gene also led to a reduction of the levels of both soyIFS2- and soyIFS1- mRNAs and an isoflavone content in the cotyledons of about 36% mature seeds of infected soybean plants. Furthermore, VIGS of soyPDS was induced in the next generation plants by the seed transmission of soyPDS-ALSV. Thus ALSV vectors will be useful for studying gene functions in the reproductive stages and early growth stages, such as emergence and cotyledon stages, in addition to the vegetative stages of soybean plants.

  6. Thomas Hardy’s Silences

    OpenAIRE

    Lecercle, Jean-Jacques

    2013-01-01

    The article aims at analysing the various forms of silence. It offers a classification of the different forms silence can take: the linguistic silence (ranging from the silence of infantia to the silence of communion, also including silence as a sign), the aesthetic silence (from the silence of the ineffable to the silence of vision or intuition), the metaphysical silence (from the silence of things to the silence of God), the narrative silence (a narrative calls a world into being by wrestin...

  7. Short-Circuit Modeling of a Wind Power Plant: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, E.; Gevorgian, V.

    2011-03-01

    This paper investigates the short-circuit behavior of a WPP for different types of wind turbines. The short-circuit behavior will be presented. Both the simplified models and detailed models are used in the simulations and both symmetrical faults and unsymmetrical faults are discussed.

  8. The NS3 protein of rice hoja blanca virus suppresses RNA silencing in mammalian cells

    NARCIS (Netherlands)

    Schnettler, E.; Hemmes, J.C.; Goldbach, R.W.; Prins, M.W.

    2008-01-01

    The NS3 protein of the tenuivirus rice hoja blanca virus (RHBV) has previously been shown to represent the viral RNA interference (RNAi) suppressor and is active in both plant and insect cells by binding short interfering RNAs (siRNAs) in vitro. Using a firefly luciferase-based silencing assay it is

  9. Short-hairpin RNA-mediated Heat shock protein 90 gene silencing inhibits human breast cancer cell growth in vitro and in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Keqiang [Department of General Surgery, Shanghai 10th People' s Hospital, Tongji University School of Medicine, Shanghai 200072 (China); Li, Dan [Department of Nuclear Medicine, Shanghai 10th People' s Hospital, Tongji University School of Medicine, Shanghai 200072 (China); Pulli, Benjamin [Center for Systems Biology, Massachusetts General Hospital, Harvard Medical School, 185 Cambridge Street, Boston, MA 02114 (United States); Yu, Fei; Cai, Haidong; Yuan, Xueyu [Department of Nuclear Medicine, Shanghai 10th People' s Hospital, Tongji University School of Medicine, Shanghai 200072 (China); Zhang, Xiaoping, E-mail: zxpsibs@163.com [Department of Nuclear Medicine, Shanghai 10th People' s Hospital, Tongji University School of Medicine, Shanghai 200072 (China); Lv, Zhongwei, E-mail: heyixue163@163.com [Department of Nuclear Medicine, Shanghai 10th People' s Hospital, Tongji University School of Medicine, Shanghai 200072 (China)

    2012-05-04

    Highlights: Black-Right-Pointing-Pointer Hsp90 is over-expressed in human breast cancer. Black-Right-Pointing-Pointer The shRNA-mediated gene silencing of Hsp90 resulted in inhibition of cell growth. Black-Right-Pointing-Pointer Akt and NF-kB were down-regulation after transfection due to Hsp90 silencing. Black-Right-Pointing-Pointer The tumor growth ratio was decline due to Hsp90 silencing. Black-Right-Pointing-Pointer The PCNA expression was down-regulation due to Hsp90 silencing. -- Abstract: Hsp90 interacts with proteins that mediate signaling pathways involved in the regulation of essential processes such as proliferation, cell cycle control, angiogenesis and apoptosis. Hsp90 inhibition is therefore an attractive strategy for blocking abnormal pathways that are crucial for cancer cell growth. In the present study, the role of Hsp90 in human breast cancer MCF-7 cells was examined by stably silencing Hsp90 gene expression with an Hsp90-silencing vector (Hsp90-shRNA). RT-PCR and Western blot analyses showed that Hsp90-shRNA specifically and markedly down-regulated Hsp90 mRNA and protein expression. NF-kB and Akt protein levels were down-regulated in Hsp90-shRNA transfected cells, indicating that Hsp90 knockout caused a reduction of survival factors and induced apoptosis. Treatment with Hsp90-shRNA significantly increased apoptotic cell death and caused cell cycle arrest in the G1/S phase in MCF-7 cells, as shown by flow cytometry. Silencing of Hsp90 also reduced cell viability, as determined by MTT assay. In vivo experiments showed that MCF-7 cells stably transfected with Hsp90-shRNA grew slowly in nude mice as compared with control groups. In summary, the Hsp90-shRNA specifically silenced the Hsp90 gene, and inhibited MCF-7 cell growth in vitro and in vivo. Possible molecular mechanisms underlying the effects of Hsp90-shRNA include the degradation of Hsp90 breast cancer-related client proteins, the inhibition of survival signals and the upregulation of apoptotic

  10. Phenotypic silencing of cytoplasmic genes using sequence-specific double-stranded short interfering RNA and its application in the reverse genetics of wild type negative-strand RNA viruses

    Directory of Open Access Journals (Sweden)

    Barik Sailen

    2001-12-01

    Full Text Available Abstract Background Post-transcriptional gene silencing (PTGS by short interfering RNA has opened up new directions in the phenotypic mutation of cellular genes. However, its efficacy on non-nuclear genes and its effect on the interferon pathway remain unexplored. Since directed mutation of RNA genomes is not possible through conventional mutagenesis, we have tested sequence-specific 21-nucleotide long double-stranded RNAs (dsRNAs for their ability to silence cytoplasmic RNA genomes. Results Short dsRNAs were generated against specific mRNAs of respiratory syncytial virus, a nonsegmented negative-stranded RNA virus with a cytoplasmic life cycle. At nanomolar concentrations, the dsRNAs specifically abrogated expression of the corresponding viral proteins, and produced the expected mutant phenotype ex vivo. The dsRNAs did not induce an interferon response, and did not inhibit cellular gene expression. The ablation of the viral proteins correlated with the loss of the specific mRNAs. In contrast, viral genomic and antigenomic RNA, which are encapsidated, were not directly affected. Conclusions Synthetic inhibitory dsRNAs are effective in specific silencing of RNA genomes that are exclusively cytoplasmic and transcribed by RNA-dependent RNA polymerases. RNA-directed RNA gene silencing does not require cloning, expression, and mutagenesis of viral cDNA, and thus, will allow the generation of phenotypic null mutants of specific RNA viral genes under normal infection conditions and at any point in the infection cycle. This will, for the first time, permit functional genomic studies, attenuated infections, reverse genetic analysis, and studies of host-virus signaling pathways using a wild type RNA virus, unencumbered by any superinfecting virus.

  11. How to use intentional silence.

    Science.gov (United States)

    Kemerer, Douglas

    2016-09-07

    Rationale and key points This article explains intentional silence, which can provide a therapeutic nursing presence that demonstrates compassion and respect for the patient. » Intentional silence can enhance the therapeutic relationship between the nurse and patient. » Intentional silence can be used to reduce the patient's emotional lability by ensuring that they feel listened to. » It is important that nurses are able to respond therapeutically to rhetorical statements and/or those concerning serious or severe clinical circumstances. » The nurse can use intentional silence to support the patient in acknowledging, processing and reflecting on changes in their health. Reflective activity 'How to' articles can help to update your practice and ensure it remains evidence based. Apply this article to your practice. Reflect on and write a short account of: 1. How this article will change your practice. 2. How you could use this article to educate your colleagues. Subscribers can upload their reflective accounts at rcni.com/portfolio.

  12. Short-Chain Chitin Oligomers: Promoters of Plant Growth

    Directory of Open Access Journals (Sweden)

    Alexander J. Winkler

    2017-02-01

    Full Text Available Chitin is the second most abundant biopolymer in nature after cellulose, and it forms an integral part of insect exoskeletons, crustacean shells, krill and the cell walls of fungal spores, where it is present as a high-molecular-weight molecule. In this study, we showed that a chitin oligosaccharide of lower molecular weight (tetramer induced genes in Arabidopsis that are principally related to vegetative growth, development and carbon and nitrogen metabolism. Based on plant responses to this chitin tetramer, a low-molecular-weight chitin mix (CHL enriched to 92% with dimers (2mer, trimers (3mer and tetramers (4mer was produced for potential use in biotechnological processes. Compared with untreated plants, CHL-treated plants had increased in vitro fresh weight (10%, radicle length (25% and total carbon and nitrogen content (6% and 8%, respectively. Our data show that low-molecular-weight forms of chitin might play a role in nature as bio-stimulators of plant growth, and they are also a known direct source of carbon and nitrogen for soil biomass. The biochemical properties of the CHL mix might make it useful as a non-contaminating bio-stimulant of plant growth and a soil restorer for greenhouses and fields.

  13. Trichodiene Production in a Trichoderma harzianum erg1-Silenced Strain Provides Evidence of the Importance of the Sterol Biosynthetic Pathway in Inducing Plant Defense-Related Gene Expression.

    Science.gov (United States)

    Malmierca, M G; McCormick, S P; Cardoza, R E; Monte, E; Alexander, N J; Gutiérrez, S

    2015-11-01

    Trichoderma species are often used as biocontrol agents against plant-pathogenic fungi. A complex molecular interaction occurs among the biocontrol agent, the antagonistic fungus, and the plant. Terpenes and sterols produced by the biocontrol fungus have been found to affect gene expression in both the antagonistic fungus and the plant. The terpene trichodiene (TD) elicits the expression of genes related to tomato defense and to Botrytis virulence. We show here that TD itself is able to induce the expression of Botrytis genes involved in the synthesis of botrydial (BOT) and also induces terpene gene expression in Trichoderma spp. The terpene ergosterol, in addition to its role as a structural component of the fungal cell membranes, acts as an elicitor of defense response in plants. In the present work, using a transformant of T. harzianum, which is silenced in the erg1 gene and accumulates high levels of squalene, we show that this ergosterol precursor also acts as an important elicitor molecule of tomato defense-related genes and induces Botrytis genes involved in BOT biosynthesis, in both cases, in a concentration-dependent manner. Our data emphasize the importance of a balance of squalene and ergosterol in fungal interactions as well as in the biocontrol activity of Trichoderma spp.

  14. Short communication: occurrence of Arcobacter species in industrial dairy plants.

    Science.gov (United States)

    Serraino, A; Giacometti, F

    2014-01-01

    The present study investigated the presence of Arcobacter spp. in industrial dairy plants. Between February and September 2013, pasteurized milk used for cheesemaking, processing and cleaning water, cheese, and environmental samples from different plant sites, including surfaces in contact or not in contact with food, were sampled. A total of 126 samples were analyzed by the cultural method and isolates were identified by multiplex PCR. Arcobacter spp. were isolated from 22 of 75 environmental samples (29.3%): of them, 22.7% were surfaces in contact with food and 38.7% surfaces not in contact with food. A total of 135 Arcobacter spp. isolates were obtained; of these, 129 and 6 were identified as Arcobacter butzleri and Arcobacter cryaerophilus, respectively. All food processing water and pasteurized milk samples were negative for Arcobacter species. We were not able to determine the primary source of contamination, but the isolation of both A. butzleri and A. cryaerophilus in surfaces in contact with food before and during manufacturing suggests that Arcobacter spp. are not or are only partially affected by routine sanitizing procedures in the industrial dairy plants studied. The efficacy of sanitizing procedures should be evaluated and further studies are needed to determine whether certain Arcobacter strains persist for long periods of time in industrial dairy plants and whether they can survive in different types of cheese in cases of postprocessing contamination.

  15. PHOTOPERIODIC HISTORY AFFECTS THE CRITICAL DAYLENGTH OF THE SHORT-DAY PLANT ACROSYMPHYTON-PURPURIFERUM (RHODOPHYTA)

    NARCIS (Netherlands)

    BREEMAN, AM

    The crustose tetrasporophyte of the red alga Acrosymphyton purpuriferum is a qualitative short-day plant in the formation of its tetrasporangia. The critical daylength for the response was determined in plants precultured in various long-day regimes [20:4, 18:6, 16:8 and 14:10 (L:D, h)]. There was a

  16. Antihyperglycemic effect of Ocimum plants: A short review

    Directory of Open Access Journals (Sweden)

    Raiya Adiba Antora

    2017-08-01

    Full Text Available This present review provides information on the antihyperglycemic effect of the plants belonging to the genus Ocimum. The species of this genus which mostly show significant antihyperglycemic effects are Ocimum tenuiflorum L., Ocimum basilicum L., Ocimum gratissimum L. and Ocimum canum L. The results were shown in both in vitro and in vivo studies. The anti-hyperglycemic activities of different extracts from all these species are reported here. Aqueous extracts are common to show a satisfactory result for all the species. The results for ethanol, methanol, ethyl-acetate, petroleum ether extracts, chloroform and hexane fraction of ethanol extract are also presented here. Some of the results showed a better effect than the standard medicine. Eugenol is the most important bioactive compound among all the components for reducing blood glucose level. Other components include polyphenols, caffeic acid, p-coumaric acid compound and chichoric acid, which are reportedly found in these species. There are fewer studies performed to identify the phytochemical components which are responsible for these plants blood glucose, serum glucose and plasma glucose lowering effect. This review presents the studies which have been done lately to establish the antihyperglycemic effects of these plants with a view to identify the core components responsible for this activity in near future.

  17. Photosynthesis Control: An underrated short-term regulatory mechanism essential for plant viability.

    Science.gov (United States)

    Colombo, Monica; Suorsa, Marjaana; Rossi, Fabio; Ferrari, Roberto; Tadini, Luca; Barbato, Roberto; Pesaresi, Paolo

    2016-01-01

    Regulation of photosynthetic electron transport provides efficient performance of oxygenic photosynthesis in plants. During the last 15 years, the molecular bases of various photosynthesis short-term regulatory processes have been elucidated, however the wild type-like phenotypes of mutants lacking of State Transitions, Non Photochemical Quenching, or Cyclic Electron Transport, when grown under constant light conditions, have also raised doubts about the acclimatory significance of these short-regulatory mechanisms on plant performance. Interestingly, recent studies performed by growing wild type and mutant plants under field conditions revealed a prominent role of State Transitions and Non Photochemical Quenching on plant fitness, with almost no effect on vegetative plant growth. Conversely, the analysis of plants lacking the regulation of electron transport by the cytochrome b6f complex, also known as Photosynthesis Control, revealed the fundamental role of this regulatory mechanism in the survival of young, developing seedlings under fluctuating light conditions.

  18. Transgenic plants expressing HC-Pro show enhanced virus sensitivity while silencing of the transgene results in resistance

    NARCIS (Netherlands)

    Mlotshwa, S.; Verver, J.; Sithole-Niang, I.; Prins, M.; Kammen, van A.; Wellink, J.

    2002-01-01

    Nicotiana benthamiana plants were engineered to express sequences of the helper component-proteinase (HC-Pro) of Cowpea aphid-borne mosaic potyvirus (CABMV). The sensitivity of the transgenic plants to infection with parental and heterologous viruses was studied. The lines expressing HC-Pro showed

  19. Robust RNAi-based resistance to mixed infection of three viruses in soybean plants expressing separate short hairpins from a single transgene.

    Science.gov (United States)

    Zhang, Xiuchun; Sato, Shirley; Ye, Xiaohong; Dorrance, Anne E; Morris, T Jack; Clemente, Thomas E; Qu, Feng

    2011-11-01

    Transgenic plants expressing double-stranded RNA (dsRNA) of virus origin have been previously shown to confer resistance to virus infections through the highly conserved RNA-targeting process termed RNA silencing or RNA interference (RNAi). In this study we applied this strategy to soybean plants and achieved robust resistance to multiple viruses with a single dsRNA-expressing transgene. Unlike previous reports that relied on the expression of one long inverted repeat (IR) combining sequences of several viruses, our improved strategy utilized a transgene designed to express several shorter IRs. Each of these short IRs contains highly conserved sequences of one virus, forming dsRNA of less than 150 bp. These short dsRNA stems were interspersed with single-stranded sequences to prevent homologous recombination during the transgene assembly process. Three such short IRs with sequences of unrelated soybean-infecting viruses (Alfalfa mosaic virus, Bean pod mottle virus, and Soybean mosaic virus) were assembled into a single transgene under control of the 35S promoter and terminator of Cauliflower mosaic virus. Three independent transgenic lines were obtained and all of them exhibited strong systemic resistance to the simultaneous infection of the three viruses. These results demonstrate the effectiveness of this very straight forward strategy for engineering RNAi-based virus resistance in a major crop plant. More importantly, our strategy of construct assembly makes it easy to incorporate additional short IRs in the transgene, thus expanding the spectrum of virus resistance. Finally, this strategy could be easily adapted to control virus problems of other crop plants.

  20. Vacuum and Co-cultivation Agroinfiltration of (Germinated) Seeds Results in Tobacco Rattle Virus (TRV) Mediated Whole-Plant Virus-Induced Gene Silencing (VIGS) in Wheat and Maize

    Science.gov (United States)

    Zhang, Ju; Yu, Deshui; Zhang, Yi; Liu, Kun; Xu, Kedong; Zhang, Fuli; Wang, Jian; Tan, Guangxuan; Nie, Xianhui; Ji, Qiaohua; Zhao, Lu; Li, Chengwei

    2017-01-01

    Tobacco rattle virus (TRV)-mediated virus-induced gene silencing (VIGS) has been frequently used in dicots. Here we show that it can also be used in monocots, by presenting a system involving use of a novel infiltration solution (containing acetosyringone, cysteine, and Tween 20) that enables whole-plant level VIGS of (germinated) seeds in wheat and maize. Using the established system, phytoene desaturase (PDS) genes were successfully silenced, resulting in typical photo-bleaching symptoms in the leaves of treated wheat and maize. In addition, three wheat homoeoalleles of MLO, a key gene repressing defense responses to powdery mildew in wheat, were simultaneously silenced in susceptible wheat with this system, resulting in it becoming resistant to powdery mildew. The system has the advantages generally associated with TRV-mediated VIGS systems (e.g., high-efficiency, mild virus infection symptoms, and effectiveness in different organs). However, it also has the following further advantages: (germinated) seed-stage agroinfiltration; greater rapidity and convenience; whole-plant level gene silencing; adequately stable transformation; and suitability for studying functions of genes involved in seed germination and early plant development stages.

  1. Practising Silence in Teaching

    Science.gov (United States)

    Forrest, Michelle

    2013-01-01

    The concept "silence" has diametrically opposed meanings; it connotes peace and contemplation as well as death and oblivion. Silence can also be considered a practice. There is keeping the rule of silence to still the mind and find inner truth, as well as forcibly silencing in the sense of subjugating another to one's own purposes.…

  2. Plant residues: short term effect on sulphate, borate, zinc and copper adsorption by an acid oxisol

    Directory of Open Access Journals (Sweden)

    Dias Ana Cristi Basile

    2003-01-01

    Full Text Available Laboratory experiments were carried out to examine the effects of plant residues on Cu, Zn, B and S adsorption by an acidic oxisol. The plant residues were: black oats (Avena strigosa, oil seed radish(Raphanus sativus, velvet beans (Stizolobium cinereum, and pigeon pea (Cajanus cajan collected at flowering stage. Plant residues increased Cu and Zn adsorptions and decreased B and S adsorptions. The results indicated that for short term effect plant residues decreased the availabilities of Cu and Zn through metal organic complex reactions and increased availabilities of S and B through competition with organic anions by the adsorption sites on soil.

  3. Flower formation in the short-day plant Kalanchoe by grafting with a long-day and a short-long-day Echeveria

    Energy Technology Data Exchange (ETDEWEB)

    Zeevaart, J.A.D.

    1978-01-01

    Flower formation was induced in the short-day plant Kalanchoe blossfeldiana Poellnitz under long-day conditions by grafting with flowering shoots of the short-long-day plant Echeveria harmsii (Rose) MacBr. and of the long-day plant Echeveria ''pulvoliver'' (E. pulvinata Rose x E. harmsii). Vegetative shoots from induced Echeveria plants failed to cause a flowering response in Kalanchoe. The presence of flowering and vegetative shoots side by side on induced Echeveria plants provides evidence for physiological chimeras in this genus.

  4. Highly efficient virus-induced gene silencing in apple and soybean by apple latent spherical virus vector and biolistic inoculation.

    Science.gov (United States)

    Yamagishi, Noriko; Yoshikawa, Nobuyuki

    2013-01-01

    Virus-induced gene silencing (VIGS) is an effective tool for the analysis of the gene function in plants within a short time. However, in woody fruit tree like apple, some of Solanum crops, and soybean, it is generally difficult to inoculate virus vector by conventional inoculation methods. Here, we show efficient VIGS in apple and soybean by Apple latent spherical virus (ALSV) vector and biolistic inoculation. The plants inoculated with ALSV vectors by particle bombardment showed uniform silenced phenotypes of target genes within 2-3 weeks post inoculation.

  5. Short communication. Plant density effect on the individual plant to plant yield variability expressed as coefficient of variation in barley

    Energy Technology Data Exchange (ETDEWEB)

    Kotzamanidis, S. T.; Lithourgidis, A. S.; Roupakias, D. G.

    2009-07-01

    The effect of plant density on the coefficient of variation (CV) for individual plant yield was studied in barley (Hordeum vulgare L.). An F2 population originating from the cross Niki x Carina was planted in three densities: high (51.32 plants m{sup -}2), intermediate (4.61 plants m{sup -}2), and low (1.15 plants m-2) using the honeycomb design. In each of the experiments, the most promising 15 plants were selected based on the individual plant yield. Progeny (F3) of the 30 plants selected from the intermediate and the low plant density were grown the following year in two experiments under an intermediate and low density. It was observed that in the F2 population the CV was reduced from 71 to 55% when the density reduced from 51.32 to 4.61 plants m{sup -}2, whereas the CV value was increased when the density was further reduced to 1.15 plants m{sup -}2. Similarly, the following year the CV was increased from 39 to 56% when the density was decreased from 4.61 to 1.15 plants m{sup -}2 in the F3 generation, and from 22 to 58% in the control. It was concluded that for barley an optimum plant density might exist under which the CV for individual plant yield is minimized and therefore the effectiveness of selection might be optimized. (Author)18 refs.

  6. Short (

    NARCIS (Netherlands)

    Telleman, Gerdien; den Hartog, Laurens

    2013-01-01

    Aim: This systematic review assessed the implant survival rate of short (<10 mm) dental implants installed in partially edentulous patients. A case report of a short implant in the posterior region have been added. Materials and methods: A search was conducted in the electronic databases of MEDLINE

  7. Short (

    NARCIS (Netherlands)

    Telleman, Gerdien; den Hartog, Laurens

    2013-01-01

    Aim: This systematic review assessed the implant survival rate of short (<10 mm) dental implants installed in partially edentulous patients. A case report of a short implant in the posterior region have been added. Materials and methods: A search was conducted in the electronic databases of MEDLINE

  8. Virus-induced gene silencing in detached tomatoes and biochemical effects of phytoene desaturase gene silencing

    NARCIS (Netherlands)

    Romero, I.; Tikunov, Y.M.; Bovy, A.G.

    2011-01-01

    Virus-induced gene silencing (VIGS) is a technology that has rapidly emerged for gene function studies in plants. Many advances have been made in applying this technique in an increasing number of crops. Recently, VIGS has been successfully used to silence genes in tomato fruit through agroinfiltrat

  9. Toxicity of selected plant volatiles in microbial and mammalian short-term assays

    NARCIS (Netherlands)

    Stammati, A.; Bonsi, P.; Zucco, F.; Moezelaar, R.; Alakomi, H.L.; von Wright, A.

    1999-01-01

    In this study, several short-term microbial and mammalian in vitro assays were used to evaluate cytotoxicity and genotoxicity of four plant volatiles showing antifungal activity: cinnamaldehyde, carvacrol, thymol and S(+)-carvone. All inhibited viability and proliferation of Hep-2 cells in a dose-de

  10. Toxicity of selected plant volatiles in microbial and mammalian short-term assays

    NARCIS (Netherlands)

    Stammati, A.; Bonsi, P.; Zucco, F.; Moezelaar, R.; Alakomi, H.L.; Wright, von A.

    1999-01-01

    In this study, several short-term microbial and mammalian in vitro assays were used to evaluate cytotoxicity and genotoxicity of four plant volatiles showing antifungal activity: cinnamaldehyde, carvacrol, thymol and S(+)-carvone. All inhibited viability and proliferation of Hep-2 cells in a dose-de

  11. Reasons of Gene Silence in Transgene Plants and Solutions%植物转基因沉默的原因及对策

    Institute of Scientific and Technical Information of China (English)

    胡增丽; 陈永文; 高峰

    2001-01-01

    转基因植物中转基因沉默已成为植物基因工程的一 大障碍.转基因沉默的原因是多方面的,可能是由于转录前外源基因和内源基因的结构特性 、位置效应以及宿主植物的遗传调控;也可能是因为转录时启动子、转录因子和终止子的作 用;还可能是由于转录后的修饰作用、外源基因表达特异性和环境等因素.为了克服转基因 植物中转基因沉默,可以采取下列对策:选择适宜的外源基因和调控元件、采用适当的转化 方法、使用更加简便快捷的筛选策略等.%In the course of commercialization plant gene engineeri ng, transgene silencing is one of obstacles. It can result from structural chara cters of transgenes and endogens, position effect and genetic regulations of hos t plants before transcription; it happens due to effects of promoter, transcript ional factor and terminator when transgenes transcript; and it appears in view o f modifications of post-transcription, specific expression of foreign genes, as well as environmental effects. Thus, we can promote expression levels of transg ene by selecting suitable transgene and regulatory elements, using advanced tran sformational methods and adopting the more concise and quicker means to select t ransformants.

  12. Promotion and inhibition of flower formation in a dayneutral plant in grafts with a short-day plant and a long-day plant

    Energy Technology Data Exchange (ETDEWEB)

    Lang, A.; Chailakhyan, M.Kh.; Frolova, I.A.

    1977-06-01

    Flower formation in the dayneutral tobacco (Nicotiana tabacum L.) cultivar ''Trapezond'' was accelerated by graft union with the short-day tobacco ''Maryland Mammoth'' when the grafts were kept on short days and by graft union with the long-day plant N. silvestris L. when they were kept on long days. When Maryland Mammoth/Trapezond grafts were kept on long days, flower formation in Trapezond was not, or only slightly, delayed compared to Trapezond/Trapezond controls; but when N. silvestris/Trapezond grafts were kept on short days, flower formation in Trapezond was inhibited and its growth changed to dwarf-like habit. The former results indicate transmission of flower-promoting material(s) (''florigen'') from photoperiodic plants maintained under flower-promoting daylength conditions to a dayneutral graft partner; the latter indicate the presence in the long-day plant N. silvestris under short-day conditions of potent flower-inhibiting and growth-regulating material(s) that can also be transmitted to a day-neutral partner. Analogous flower-inhibitory materials seem not to be present, or to be present to a much lesser extent, in the short-day plant Maryland Mammoth under long-day conditions.

  13. Hitchcock's Melodramatic Silence.

    Science.gov (United States)

    Hemmeter, Thomas

    1996-01-01

    Argues that the filmwork of Alfred Hitchcock shows his manipulation of melodramatic silence in that his films demonstrate a link between silence and truth. Concludes that in the simultaneous longing for and denial of the power of film silence lies the modernist complexity of Hitchcock's films that suggests the uses of melodramatic language in a…

  14. Efficient short-term scheduling of multiproduct batch plants under demand uncertainty

    Institute of Scientific and Technical Information of China (English)

    Jin Zhu; Xingsheng Gu; Bin Jiao

    2008-01-01

    In this paper, a novel formulation for the short-term scheduling of multiproduct batch plants under demand uncertainty is presented. Then it is solved by an improved genetic algorithm. The proposed approach results in an efficient utilization of the plant capability as it allows the optimal selection among all the rescheduling alternatives in a systematic way without the use of any heuristics. Moreover, the objective function can not only maximize the total profit of the plant and minimize the makespan but also allow the flexibility for modeling different weighted instances of the two targets so that a best-possible decision can be determined. According to the discrete characteristic of scheduling of batch plants, through the improvement of the coding method, an effective genetic algorithm is presented. Two examples are given to illustrate the effectiveness of the proposed formulation and algorithm.

  15. Retraction: "An enhanced transient expression system in plants based on suppression of gene silencing by the p19 protein of tomato bushy stunt virus".

    Science.gov (United States)

    2015-11-01

    Retracted: An enhanced transient expression system in plants based on suppression of gene silencing by the p19 protein of tomato bushy stunt virus Volume 33, Issue 5, 949–956, Article first published online: 28 February 2003. The above article, first published online on 28 February 2003 in Wiley Online Library (wileyonlinelibrary.com), and in volume 33, pp. 949–956, has been retracted by agreement between the authors, the journal Editor in Chief, Christoph Benning, and John Wiley & Sons Ltd.This notice updates and replaces a recent correction notice, published on 8 June 2015.In the above article, it has recently been noted that the original Figure 3b in this paper was assembled incorrectly and included image duplications. As the original data are no longer available for assembly of a corrected figure, the experiment was repeated, in agreement with the editors, by co-author S. Rivas. The data from the repeated experiment, presented below together with the original figure legend, lead to the same interpretation and conclusions as in the original paper.Since publication of the above notice the corresponding author has become aware of additional image duplications involving the loading control lanes of Figures 2g, 3a, 4e and 4f. The authors accept that integrity of the scientific literature is compromised by the data manipulation and, for that reason, they wish to retract the article. However, researchers wishing to use the method described in this paper can still obtain the necessary clones from the corresponding author (dcb40@cam.ac.uk). The authors apologise for having allowed this flawed article to be published.

  16. Superior Silencing by 2′,4′-BNANC-Based Short Antisense Oligonucleotides Compared to 2′,4′-BNA/LNA-Based Apolipoprotein B Antisense Inhibitors

    Directory of Open Access Journals (Sweden)

    Tsuyoshi Yamamoto

    2012-01-01

    Full Text Available The duplex stability with target mRNA and the gene silencing potential of a novel bridged nucleic acid analogue are described. The analogue, 2′,4′-BNANC antisense oligonucleotides (AONs ranging from 10- to 20-nt-long, targeted apolipoprotein B. 2′,4′-BNANC was directly compared to its conventional bridged (or locked nucleic acid (2′,4′-BNA/LNA-based counterparts. Melting temperatures of duplexes formed between 2′,4′-BNANC-based antisense oligonucleotides and the target mRNA surpassed those of 2′,4′-BNA/LNA-based counterparts at all lengths. An in vitro transfection study revealed that when compared to the identical length 2′,4′-BNA/LNA-based counterpart, the corresponding 2′,4′-BNANC-based antisense oligonucleotide showed significantly stronger inhibitory activity. This inhibitory activity was more pronounced in shorter (13-, 14-, and 16-mer oligonucleotides. On the other hand, the 2′,4′-BNANC-based 20-mer AON exhibited the highest affinity but the worst IC50 value, indicating that very high affinity may undermine antisense potency. These results suggest that the potency of AONs requires a balance between reward term and penalty term. Balance of these two parameters would depend on affinity, length, and the specific chemistry of the AON, and fine-tuning of this balance could lead to improved potency. We demonstrate that 2′,4′-BNANC may be a better alternative to conventional 2′,4′-BNA/LNA, even for “short” antisense oligonucleotides, which are attractive in terms of drug-likeness and cost-effective bulk production.

  17. Le rythme du silence

    OpenAIRE

    Meschonnic, Henri

    2017-01-01

    1. Pour rompre le silence Dire « rythme du silence », c’est non seulement penser le silence comme langage, et parfois la réalisation maximale du langage, mais aussi parcourir les acceptions de la notion de silence. De ce qui n’est pas dit, ou qu’on est incapable de dire à ce que les mots ne peuvent pas dire, le fameux indicible, mais aussi l’innommable, et la censure, faire silence sur, jusqu’au problème poétique. Il y a aussi une langue de bois du silence. Et aussi le silence de ce qu’on ent...

  18. RNAi silencing of a cytochrome P450 monooxygenase disrupts the ability of a filamentous fungus, Graphium sp. to grow on short-chain gaseous alkanes and ethers

    Science.gov (United States)

    Graphium sp. (ATCC 58400), a filamentous fungus, is one of the few eukaryotes that grows on short-chain alkanes and ethers. In this study, we investigated the genetic underpinnings that enable this fungus to catalyze the first step in the alkane and ether oxidation pathway. A gene, CYP52L1, was iden...

  19. Short Rotation Coppice (SRC) Plantations Provide Additional Habitats for Vascular Plant Species in Agricultural Mosaic Landscapes

    OpenAIRE

    BAUM, Sarah; Bolte, Andreas; Weih, Martin

    2012-01-01

    Increasing loss of biodiversity in agricultural landscapes is often debated in the bioenergy context, especially with respect to non-traditional crops that can be grown for energy production in the future. As promising renewable energy source and additional landscape element, the potential role of short rotation coppice (SRC) plantations to biodiversity is of great interest. We studied plant species richness in eight landscapes (225 km2) containing willow and poplar SRC plantations (1,600 m2)...

  20. Virus-induced gene silencing in detached tomatoes and biochemical effects of phytoene desaturase gene silencing.

    Science.gov (United States)

    Romero, Irene; Tikunov, Yury; Bovy, Arnaud

    2011-07-01

    Virus-induced gene silencing (VIGS) is a technology that has rapidly emerged for gene function studies in plants. Many advances have been made in applying this technique in an increasing number of crops. Recently, VIGS has been successfully used to silence genes in tomato fruit through agroinfiltration of fruit attached to the plant. The phytoene desaturase (Pds) gene has been widely used as a reporter gene in VIGS experiments, although little is known about the changes that occur due to its silencing in plants. In this paper, we describe the efficient silencing of the Pds gene through the VIGS approach in detached tomato fruits, which makes the VIGS procedure even more versatile and applicable. After 16 days of agroinfiltration, approximately 75% of the tomatoes showed Pds silencing symptoms, although the distribution of silenced areas was variable among fruits. To study the potential effects caused by Pds silencing in detached tomatoes, carotenoids and other semi-polar secondary metabolites were analyzed using Liquid Chromatography-Mass Spectrometry. In addition, potential differences in primary metabolites were analyzed using Gas Chromatography-Mass Spectrometry. The results indicated that the yellow phenotype observed in Pds-silenced fruit was mainly due to the lack of the red-colored lycopene and therefore to a more pronounced contribution of the yellow-orange carotenoids (lutein, violaxanthin, and zeaxanthin) to the final color of the fruits. Furthermore, the biochemical changes observed in Pds-silenced detached tomatoes suggested that carotenoid and other pathways, e.g. leading to alkaloids and flavonoids, might be affected by the silencing of this reporter gene, and this should be taken into consideration for future experimental designs.

  1. Seeds of alpine plants are short lived: implications for long-term conservation.

    Science.gov (United States)

    Mondoni, Andrea; Probert, Robin J; Rossi, Graziano; Vegini, Emanuele; Hay, Fiona R

    2011-01-01

    Alpine plants are considered one of the groups of species most sensitive to the direct and indirect threats to ecosystems caused by land use and climate change. Collecting and banking seeds of plant species is recognized as an effective tool for providing propagating material to re-establish wild plant populations and for habitat repair. However, seeds from cold wet environments have been shown to be relatively short lived in storage, and therefore successful long-term seed conservation for alpine plants may be difficult. Here, the life spans of 69 seed lots representing 63 related species from alpine and lowland locations from northern Italy are compared. Seeds were placed into experimental storage at 45 °C and 60 % relative humidity (RH) and regularly sampled for germination. The time taken in storage for viability to fall to 50 % (p(50)) was determined using probit analysis and used as a measure of relative seed longevity between seed lots. Across species, p(50) at 45 °C and 60 % RH varied from 4·7 to 95·5 d. Seed lots from alpine populations/species had significantly lower p(50) values compared with those from lowland populations/species; the lowland seed lots showed a slower rate of loss of germinability, higher initial seed viability, or both. Seeds were progressively longer lived with increased temperature and decreased rainfall at the collecting site. Seeds of alpine plants are short lived in storage compared with those from lowland populations/related taxa. The lower resistance to ageing in seeds of alpine plants may arise from low selection pressure for seed resistance to ageing and/or damage incurred during seed development due to the cool wet conditions of the alpine climate. Long-term seed conservation of several alpine species using conventional seed banking methods will be problematic.

  2. A dominant mutation in mediator of paramutation2, one of three second-largest subunits of a plant-specific RNA polymerase, disrupts multiple siRNA silencing processes.

    Directory of Open Access Journals (Sweden)

    Lyudmila Sidorenko

    2009-11-01

    Full Text Available Paramutation involves homologous sequence communication that leads to meiotically heritable transcriptional silencing. We demonstrate that mop2 (mediator of paramutation2, which alters paramutation at multiple loci, encodes a gene similar to Arabidopsis NRPD2/E2, the second-largest subunit of plant-specific RNA polymerases IV and V. In Arabidopsis, Pol-IV and Pol-V play major roles in RNA-mediated silencing and a single second-largest subunit is shared between Pol-IV and Pol-V. Maize encodes three second-largest subunit genes: all three genes potentially encode full length proteins with highly conserved polymerase domains, and each are expressed in multiple overlapping tissues. The isolation of a recessive paramutation mutation in mop2 from a forward genetic screen suggests limited or no functional redundancy of these three genes. Potential alternative Pol-IV/Pol-V-like complexes could provide maize with a greater diversification of RNA-mediated transcriptional silencing machinery relative to Arabidopsis. Mop2-1 disrupts paramutation at multiple loci when heterozygous, whereas previously silenced alleles are only up-regulated when Mop2-1 is homozygous. The dramatic reduction in b1 tandem repeat siRNAs, but no disruption of silencing in Mop2-1 heterozygotes, suggests the major role for tandem repeat siRNAs is not to maintain silencing. Instead, we hypothesize the tandem repeat siRNAs mediate the establishment of the heritable silent state-a process fully disrupted in Mop2-1 heterozygotes. The dominant Mop2-1 mutation, which has a single nucleotide change in a domain highly conserved among all polymerases (E. coli to eukaryotes, disrupts both siRNA biogenesis (Pol-IV-like and potentially processes downstream (Pol-V-like. These results suggest either the wild-type protein is a subunit in both complexes or the dominant mutant protein disrupts both complexes. Dominant mutations in the same domain in E. coli RNA polymerase suggest a model for Mop2

  3. DEMOGRAPHY OF ALPINE SHORT-LIVED PLANTS, LONGEVITY AND ONTOGENY STAGE DURATIONS

    Directory of Open Access Journals (Sweden)

    E. S. Kazantseva

    2016-01-01

    Full Text Available The aim - to evaluate lifespan (full cycle and ontogeny stage durations of nine alpine short-lived North- West Caucasus plants.Methods. For calculation we used a new method which was developed and suggested earlier by us. This method is based on a discrete ontogeny description and on the probability theory and random processes. The data on the monitoring of the marked individuals were collected during six years.Results. We found out that the lifespan of Anthyllis vulneraria is 2.6±0.3 years (hereinafter “±” is Standard error, Draba hispida – 4.5±0.3, Murbeckiella huetii – 4.6±1.1, Carum meifolium – 7.8±1.4, Eritrichium caucasicum – 9.1±1.4, Trifolium badium – 10.3±2.6, Sedum tenellum – 11±2.05, Androsace albana – 12.1±2.5, Minuartia recurva – 22.9±4.5. Also we demonstrated the matrix population models for studied plants, which show the probability of transition of individuals from one ontogeny stage to another in time interval (in our experiment – 1 year.Conclusion. Mortality of seedlings and juvenile plants, except Murbeckiella huetii, is around and more than 50%. Two years is the minimal amount of time that is necessary for full cycle of short-lived alpine plants, as it was shown for Anthyllis vulneraria, Murbeckiella huetii и Trifolium badium. A 3-12 years lifespan was calculated for other studied species. Persistence of Eritrichium caucasicum and Androsace albana populations provided by resistance of adult vegetative plants.

  4. The plant short-chain dehydrogenase (SDR) superfamily: genome-wide inventory and diversification patterns.

    Science.gov (United States)

    Moummou, Hanane; Kallberg, Yvonne; Tonfack, Libert Brice; Persson, Bengt; van der Rest, Benoît

    2012-11-20

    Short-chain dehydrogenases/reductases (SDRs) form one of the largest and oldest NAD(P)(H) dependent oxidoreductase families. Despite a conserved 'Rossmann-fold' structure, members of the SDR superfamily exhibit low sequence similarities, which constituted a bottleneck in terms of identification. Recent classification methods, relying on hidden-Markov models (HMMs), improved identification and enabled the construction of a nomenclature. However, functional annotations of plant SDRs remain scarce. Wide-scale analyses were performed on ten plant genomes. The combination of hidden Markov model (HMM) based analyses and similarity searches led to the construction of an exhaustive inventory of plant SDR. With 68 to 315 members found in each analysed genome, the inventory confirmed the over-representation of SDRs in plants compared to animals, fungi and prokaryotes. The plant SDRs were first classified into three major types - 'classical', 'extended' and 'divergent' - but a minority (10% of the predicted SDRs) could not be classified into these general types ('unknown' or 'atypical' types). In a second step, we could categorize the vast majority of land plant SDRs into a set of 49 families. Out of these 49 families, 35 appeared early during evolution since they are commonly found through all the Green Lineage. Yet, some SDR families - tropinone reductase-like proteins (SDR65C), 'ABA2-like'-NAD dehydrogenase (SDR110C), 'salutaridine/menthone-reductase-like' proteins (SDR114C), 'dihydroflavonol 4-reductase'-like proteins (SDR108E) and 'isoflavone-reductase-like' (SDR460A) proteins - have undergone significant functional diversification within vascular plants since they diverged from Bryophytes. Interestingly, these diversified families are either involved in the secondary metabolism routes (terpenoids, alkaloids, phenolics) or participate in developmental processes (hormone biosynthesis or catabolism, flower development), in opposition to SDR families involved in primary

  5. Short Term Effect of Salt Shock on Ethylene and Polyamines Depends on Plant Salt Sensitivity

    Directory of Open Access Journals (Sweden)

    Pedro J. Zapata

    2017-05-01

    Full Text Available In the present manuscript the short term effect (3–24 h of a saline shock (NaCl 100 mM on fresh weight, water content, respiration rate, ethylene production and Na+, Cl-, ACC and polyamine concentration was studied in four plant species with different salt sensitivity, pepper, lettuce, spinach, and beetroot. Higher reduction in fresh weight and water content as a consequence of saline shock was found in pepper and lettuce plants than in spinach and beetroot, the latter behaving as more salinity tolerant. In general, salinity led to rapid increases in respiration rate, ethylene production and ACC and polyamine (putrescine, spermidine, and spermine concentrations in shoot and root. These increases were related to plant salinity sensitivity, since they were higher in the most sensitive species and vice versa. However, ethylene and respiration rates in salt stressed plants recovered similar values to controls after 24 h of treatment in salt tolerant plants, while still remaining high in the most sensitive. On the other hand, sudden increases in putrescine, spermidine, and spermine concentration were higher and occurred earlier in pepper and lettuce, the most sensitive species, than in spinach and beetroot, the less sensitive ones. These increases tended to disappear after 24 h, except in lettuce. These changes would support the conclusion that ethylene and polyamine increases could be considered as a plant response to saline shock and related to the plant species sensitivity to this stress. In addition, no competition between polyamines and ethylene biosynthesis for their common precursor was observed.

  6. The Plant Short-Chain Dehydrogenase (SDR superfamily: genome-wide inventory and diversification patterns

    Directory of Open Access Journals (Sweden)

    Moummou Hanane

    2012-11-01

    Full Text Available Abstract Background Short-chain dehydrogenases/reductases (SDRs form one of the largest and oldest NAD(P(H dependent oxidoreductase families. Despite a conserved ‘Rossmann-fold’ structure, members of the SDR superfamily exhibit low sequence similarities, which constituted a bottleneck in terms of identification. Recent classification methods, relying on hidden-Markov models (HMMs, improved identification and enabled the construction of a nomenclature. However, functional annotations of plant SDRs remain scarce. Results Wide-scale analyses were performed on ten plant genomes. The combination of hidden Markov model (HMM based analyses and similarity searches led to the construction of an exhaustive inventory of plant SDR. With 68 to 315 members found in each analysed genome, the inventory confirmed the over-representation of SDRs in plants compared to animals, fungi and prokaryotes. The plant SDRs were first classified into three major types — ‘classical’, ‘extended’ and ‘divergent’ — but a minority (10% of the predicted SDRs could not be classified into these general types (‘unknown’ or ‘atypical’ types. In a second step, we could categorize the vast majority of land plant SDRs into a set of 49 families. Out of these 49 families, 35 appeared early during evolution since they are commonly found through all the Green Lineage. Yet, some SDR families — tropinone reductase-like proteins (SDR65C, ‘ABA2-like’-NAD dehydrogenase (SDR110C, ‘salutaridine/menthone-reductase-like’ proteins (SDR114C, ‘dihydroflavonol 4-reductase’-like proteins (SDR108E and ‘isoflavone-reductase-like’ (SDR460A proteins — have undergone significant functional diversification within vascular plants since they diverged from Bryophytes. Interestingly, these diversified families are either involved in the secondary metabolism routes (terpenoids, alkaloids, phenolics or participate in developmental processes (hormone biosynthesis or

  7. Anti Diabetic Plants Present In West Godavari District Of Andhra Pradesh India- A Short Review.

    Directory of Open Access Journals (Sweden)

    Venkata Narasimha Kadali

    2016-02-01

    Full Text Available Diabetes is considered as one of the chronic disease more prevalent in India and rest of the world. Chronic hyperglycemia leads to the destruction of different organs in the body.There are lots of synthetic drugs present in the market for the treatment of diabetes but they are prone to noxious effects to human systems. Herbs have natural inhibiting potency against various sorts of diseases and they are the ultimate source of bio active compounds which lacks toxic effects. Medicinal plants which have potent anti hyperglycemic effect have been identified and proved experimentally. In this short review an attempt has been made to review some of the medicinal plants such as Annona reticulata, Carica papaya, Coccinia grandis, Moringa oleifera, Murraya koenigi etc., of about 10 species which are proved to be anti diabetic present in the west godavari district of Andhra Pradesh, India.

  8. A short latency between radiation exposure from nuclear plants and cancer in young children.

    Science.gov (United States)

    Mangano, Joseph J

    2006-01-01

    Previous reports document a short latency of cancer onset in young children exposed to low doses of radioactivity. The standard mortality ratio (SMR) for cancer in children dying before age ten rose in the period 6-10 years after the Three Mile Island and Chernobyl accidents in populations most exposed to fallout. SMRs near most nuclear power plants were elevated 6-10 years after startup, particularly for leukemia. Cancer incidence in children under age ten living near New York and New Jersey nuclear plants increased 4-5 years after increases in average strontium-90 in baby teeth, and declined 4-5 years after Sr-90 averages dropped. The assumption that Sr-90 and childhood cancer are correlated is best supported for a supralinear dose-response, meaning the greatest per-dose risks are at the lowest doses. Findings document that the very young are especially susceptible to adverse effects of radiation exposure, even at relatively low doses.

  9. An overview of organically bound tritium experiments in plants following a short atmospheric HTO exposure.

    Science.gov (United States)

    Galeriu, D; Melintescu, A; Strack, S; Atarashi-Andoh, M; Kim, S B

    2013-04-01

    The need for a less conservative, but reliable risk assessment of accidental tritium releases is emphasized in the present debate on the nuclear energy future. The development of a standard conceptual model for accidental tritium releases must be based on the process level analysis and the appropriate experimental database. Tritium transfer from atmosphere to plants and the subsequent conversion into organically bound tritium (OBT) strongly depends on the plant characteristics, seasons, and meteorological conditions, which have a large variability. The present study presents an overview of the relevant experimental data for the short term exposure, including the unpublished information, also. Plenty of experimental data is provided for wheat, rice, and soybean and some for potato, bean, cherry tomato, radish, cabbage, and tangerine as well. Tritiated water (HTO) uptake by plants during the daytime and nighttime has an important role in further OBT synthesis. OBT formation in crops depends on the development stage, length, and condition of exposure. OBT translocation to the edible plant parts differs between the crops analyzed. OBT formation during the nighttime is comparable with that during the daytime. The present study is a preliminary step for the development of a robust model of crop contamination after an HTO accidental release. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Short-Term Power Forecasting Model for Photovoltaic Plants Based on Historical Similarity

    Directory of Open Access Journals (Sweden)

    M. Sonia Terreros-Olarte

    2013-05-01

    Full Text Available This paper proposes a new model for short-term forecasting of electric energy production in a photovoltaic (PV plant. The model is called HIstorical SImilar MIning (HISIMI model; its final structure is optimized by using a genetic algorithm, based on data mining techniques applied to historical cases composed by past forecasted values of weather variables, obtained from numerical tools for weather prediction, and by past production of electric power in a PV plant. The HISIMI model is able to supply spot values of power forecasts, and also the uncertainty, or probabilities, associated with those spot values, providing new useful information to users with respect to traditional forecasting models for PV plants. Such probabilities enable analysis and evaluation of risk associated with those spot forecasts, for example, in offers of energy sale for electricity markets. The results of spot forecasting of an illustrative example obtained with the HISIMI model for a real-life grid-connected PV plant, which shows high intra-hour variability of its actual power output, with forecasting horizons covering the following day, have improved those obtained with other two power spot forecasting models, which are a persistence model and an artificial neural network model.

  11. Screening and identification of virus-encoded RNA silencing suppressors.

    Science.gov (United States)

    Karjee, Sumona; Islam, Mohammad Nurul; Mukherjee, Sunil K

    2008-01-01

    RNA silencing, including RNA interference, is a novel method of gene regulation and one of the potent host-defense mechanisms against the viruses. In the course of evolution, the viruses have encoded proteins with the potential to suppress the host RNA silencing mechanism as a counterdefense strategy. The virus-encoded RNA silencing suppressors (RSSs) can serve as important biological tools to dissect the detailed RNA silencing pathways and also to evolve the antiviral strategies. Screening and identification of the RSSs are indeed of utmost significance in the field of plant biotechnology. We describe two Green Fluorescent Protein (GFP) reporter-based plant assay systems that rely on two different principles, namely reversal of silencing and enhancement of rolling circle replication (RCR) of geminiviral replicon. These proof-of-concept examples and assay systems could be used to screen various plant, animal, and insect viral ORFs for identification of the RSS activities.

  12. Strategies underlying RNA silencing suppression by negative strand RNA viruses

    NARCIS (Netherlands)

    Hemmes, J.C.

    2007-01-01

    The research described in this thesis focused on the strategies of negative strand RNA viruses to counteract antiviral RNA silencing. In plants and insects, RNA silencing has been shown to act as a sequence specific antiviral defence mechanism that is characterised by the processing of double strand

  13. Strategies underlying RNA silencing suppression by negative strand RNA viruses

    NARCIS (Netherlands)

    Hemmes, J.C.

    2007-01-01

    The research described in this thesis focused on the strategies of negative strand RNA viruses to counteract antiviral RNA silencing. In plants and insects, RNA silencing has been shown to act as a sequence specific antiviral defence mechanism that is characterised by the processing of double strand

  14. A new virus-induced gene silencing vector based on Euphorbia mosaic virus-Yucatan peninsula for NPR1 silencing in Nicotiana benthamiana and Capsicum annuum var. Anaheim.

    Science.gov (United States)

    Villanueva-Alonzo, Hernan J; Us-Camas, Rosa Y; López-Ochoa, Luisa A; Robertson, Dominique; Guerra-Peraza, Orlene; Minero-García, Yereni; Moreno-Valenzuela, Oscar A

    2013-05-01

    Virus-induced gene silencing is based on the sequence-specific degradation of RNA. Here, a gene silencing vector derived from EuMV-YP, named pEuMV-YP:ΔAV1, was used to silence ChlI and NPR1 genes in Nicotiana benthamiana. The silencing of the ChlI transcripts was efficient in the stems, petioles and leaves as reflected in tissue bleaching and reduced transcript levels. The silencing was stable, reaching the flowers and fruits, and was observed throughout the life cycle of the plants. Additionally, the silencing of the NPR1 gene was efficient in both N. benthamiana and Capsicum annuum. After silencing, the plants' viral symptoms increased to levels similar to those seen in wild-type plants. These results suggest that NPR1 plays a role in the compatible interactions of EuMV-YP N. benthamiana and EuMV-C. annum var. anaheim.

  15. Short-Term Forecasting Models for Photovoltaic Plants: Analytical versus Soft-Computing Techniques

    Directory of Open Access Journals (Sweden)

    Claudio Monteiro

    2013-01-01

    Full Text Available We present and compare two short-term statistical forecasting models for hourly average electric power production forecasts of photovoltaic (PV plants: the analytical PV power forecasting model (APVF and the multiplayer perceptron PV forecasting model (MPVF. Both models use forecasts from numerical weather prediction (NWP tools at the location of the PV plant as well as the past recorded values of PV hourly electric power production. The APVF model consists of an original modeling for adjusting irradiation data of clear sky by an irradiation attenuation index, combined with a PV power production attenuation index. The MPVF model consists of an artificial neural network based model (selected among a large set of ANN optimized with genetic algorithms, GAs. The two models use forecasts from the same NWP tool as inputs. The APVF and MPVF models have been applied to a real-life case study of a grid-connected PV plant using the same data. Despite the fact that both models are quite different, they achieve very similar results, with forecast horizons covering all the daylight hours of the following day, which give a good perspective of their applicability for PV electric production sale bids to electricity markets.

  16. Estimation of waste water treatment plant methane emissions: methodology and results from a short campaign

    Directory of Open Access Journals (Sweden)

    C. E. Yver-Kwok

    2013-10-01

    Full Text Available This paper describes different methods to estimate methane emissions at different scales. These methods are applied to a waste water treatment plant (WWTP located in Valence, France. We show that Fourier Transform Infrared (FTIR measurements as well as Cavity Ring Down Spectroscopy (CRDS can be used to measure emissions from the process to the regional scale. To estimate the total emissions, we investigate a tracer release method (using C2H2 and the Radon tracer method (using 222Rn. For process-scale emissions, both tracer release and chamber techniques were used. We show that the tracer release method is suitable to quantify facility- and some process-scale emissions, while the Radon tracer method encompasses not only the treatment station but also a large area around. Thus the Radon tracer method is more representative of the regional emissions around the city. Uncertainties for each method are described. Applying the methods to CH4 emissions, we find that the main source of emissions of the plant was not identified with certainty during this short campaign, although the primary source of emissions is likely to be from solid sludge. Overall, the waste water treatment plant represents a small part (3% of the methane emissions of the city of Valence and its surroundings,which is in agreement with the national inventories.

  17. Deletion of fucose residues in plant N-glycans by repression of the GDP-mannose 4,6-dehydratase gene using virus-induced gene silencing and RNA interference.

    Science.gov (United States)

    Matsuo, Kouki; Matsumura, Takeshi

    2011-02-01

    Production of pharmaceutical glycoproteins in plants has many advantages in terms of safety and reduced costs. However, plant-produced glycoproteins have N-glycans with plant-specific sugar residues (core β-1,2-xylose and α-1,3-fucose) and a Lewis a (Le(a) ) epitope, i.e., Galβ(1-3)[Fucα(1-4)]GlcNAc. Because these sugar residues and glycan structures seemed to be immunogenic, several attempts have been made to delete them by repressing their respective glycosyltransferase genes. However, until date, such deletions have not been successful in completely eliminating the fucose residues. In this study, we simultaneously reduced the plant-specific core α-1,3-fucose and α-1,4-fucose residues in the Le(a) epitopes by repressing the Guanosine 5'-diphosphate (GDP)-D-mannose 4,6-dehydratase (GMD) gene, which is associated with GDP-L-fucose biosynthesis, in Nicotiana benthamiana plants. Repression of GMD was achieved using virus-induced gene silencing (VIGS) and RNA interference (RNAi). The proportion of fucose-free N-glycans found in total soluble protein from GMD gene-repressed plants increased by 80% and 95% following VIGS and RNAi, respectively, compared to wild-type plants. A small amount of putative galactose substitution in N-glycans from the NbGMD gene-repressed plants was observed, similar to what has been previously reported GMD-knockout Arabidopsis mutant. On the other hand, the recombinant mouse granulocyte-macrophage colony-stimulating factor (GM-CSF) with fucose-deleted N-glycans was successfully produced in NbGMD-RNAi transgenic N. benthamiana plants. Thus, repression of the GMD gene is thus very useful for deleting immunogenic total fucose residues and facilitating the production of pharmaceutical glycoproteins in plants.

  18. Silence in Business Negotiation

    Institute of Scientific and Technical Information of China (English)

    杨娅琼; 杨敭

    2011-01-01

    @@ Ⅰ、Introduction Silence is the relative or total lack of audible sound.In our daily life, it is an indispensable part of communication, in reference to non verbal communication. When used in business negotiation, silence is the rhetorical practice of saying nothing when an opponent expects something to be said.Poorly executed, it can be very offensive, which would even bring a negotiation into a deadlock.However, well-timed silence can completely throw an opponent and give the negotiator the upper hand.

  19. Evaluating the ability of the barley stripe mosaic virus-induced gene silencing system to simultaneously silence two wheat genes

    Science.gov (United States)

    Virus-induced gene silencing (VIGS) is an important tool for rapid assessment of gene function in plants. The ability of the Barley Stripe Mosaic Virus (BSMV) VIGS system to simultaneously silence two genes was assessed by comparing the extent of down-regulation of the wheat PDS and SGT1 genes afte...

  20. Ombuds’ corner: Employee silence

    CERN Multimedia

    Vincent Vuillemin

    2013-01-01

    Although around a hundred cases a year are reported to the Ombuds, several issues may still not be disclosed due to employee silence*. The deliberate withholding of concerns, escalating misunderstandings or genuine conflicts can impede the global process of learning and development of a better respectful organizational workplace environment, and prevent the detection and correction of acts violating the CERN Code of Conduct.   For the employee him/herself, such silence can lead to feelings of anger, resentment, helplessness and humiliation. These feelings will inevitably contaminate personal and interpersonal relations, and poison creativity and effectiveness. Employee silence can be explained by many factors; sometimes it is connected to organizational forces. In their published paper*, authors Michael Knoll and Rolf van Dick found four forms of employee silence. People may stay silent if they feel that their opinion is neither welcomed nor valued by their management. They have gi...

  1. A contribution to identification of novel regulators of plant response to sulfur deficiency: characteristics of a tobacco gene UP9C, its protein product and the effects of UP9C silencing.

    Science.gov (United States)

    Lewandowska, Malgorzata; Wawrzynska, Anna; Moniuszko, Grzegorz; Lukomska, Jolanta; Zientara, Katarzyna; Piecho, Marta; Hodurek, Pawel; Zhukov, Igor; Liszewska, Frantz; Nikiforova, Victoria; Sirko, Agnieszka

    2010-03-01

    Extensive changes in plant transcriptome and metabolome have been observed by numerous research groups after transferring plants from optimal conditions to sulfur (S) deficiency. Despite intensive studies and recent important achievements, like identification of SLIM1/EIL3 as a major transcriptional regulator of the response to S-deficiency, many questions concerning other elements of the regulatory network remain unanswered. Investigations of genes with expression regulated by S-deficiency stress encoding proteins of unknown function might help to clarify these problems. This study is focused on the UP9C gene and the UP9-like family in tobacco. Homologs of these genes exist in other plant species, including a family of four genes of unknown function in Arabidopsis thaliana (LSU1-4), of which two were reported as strongly induced by S-deficit and to a lesser extent by salt stress and nitrate limitation. Conservation of the predicted structural features, such as coiled coil region or nuclear localization signal, suggests that these proteins might have important functions possibly mediated by interactions with other proteins. Analysis of transgenic tobacco plants with silenced expression of UP9-like genes strongly argues for their significant role in regulation of plant response to S-deficit. Although our study shows that the UP9-like proteins are important components of such response and they might be also required during other stresses, their molecular functions remain a mystery.

  2. Identification of Pns6, a putative movement protein of RRSV, as a silencing suppressor

    Directory of Open Access Journals (Sweden)

    Lin Qiying

    2010-11-01

    Full Text Available Abstract RNA silencing is a potent antiviral response in plants. As a counterdefense, most plant and some animal viruses encode RNA silencing suppressors. In this study, we showed that Pns6, a putative movement protein of Rice ragged stunt virus (RRSV, exhibited silencing suppressor activity in coinfiltration assays with the reporter green fluorescent protein (GFP in transgenic Nicotiana benthamiana line 16c. Pns6 of RRSV suppressed local silencing induced by sense RNA but had no effect on that induced by dsRNA. Deletion of a region involved in RNA binding abolished the silencing suppressor activity of Pns6. Further, expression of Pns6 enhanced Potato virus × pathogenicity in N. benthamiana. Collectively, these results suggested that RRSV Pns6 functions as a virus suppressor of RNA silencing that targets an upstream step of the dsRNA formation in the RNA silencing pathway. This is the first silencing suppressor to be identified from the genus Oryzavirus.

  3. Toxicity of selected plant volatiles in microbial and mammalian short-term assays.

    Science.gov (United States)

    Stammati, A; Bonsi, P; Zucco, F; Moezelaar, R; Alakomi, H L; von Wright, A

    1999-08-01

    In this study, several short-term microbial and mammalian in vitro assays were used to evaluate cytotoxicity and genotoxicity of four plant volatiles showing antifungal activity: cinnamaldehyde, carvacrol, thymol and S(+)-carvone. All inhibited viability and proliferation of Hep-2 cells in a dose-dependent manner. IC50 ranged from 0.3 mM (cinnamaldehyde) to 0.7 mM (thymol) in viability tests and from 0.2 mM (carvacrol) to 0.9 mM (carvone) in the proliferation test. The morphological analysis suggested an involvement of apoptosis in the cases of carvone, carvacrol and cinnamaldehyde. At nontoxic doses, carvacrol and thymol increased the number of revertants in the Ames test by 1.5-1.7 times, regardless of metabolic activation. In the SOS-chromotest, none of the four plant volatiles caused DNA damage at non-toxic doses. In the DNA repair test, a marked dose-dependent differential toxicity was observed with carvone and, to a lesser extent, with cinnamaldehyde, while with thymol and carvacrol, this effect was less pronounced. In conclusion, the considered in vitro cytotoxicity assays have shown to be sensitive enough to highlight a variety of toxic effects at the cellular level, which can be rather different between chemically closely related compounds, such as isomers.

  4. Plant oils as feedstock alternatives to petroleum - A short survey of potential oil crop platforms.

    Science.gov (United States)

    Carlsson, Anders S

    2009-06-01

    Our society is highly depending on petroleum for its activities. About 90% is used as an energy source for transportation and for generation of heat and electricity and the remaining as feedstocks in the chemical industry. However, petroleum is a finite source as well as causing several environmental problems such as rising carbon dioxide levels in the atmosphere. Petroleum therefore needs to be replaced by alternative and sustainable sources. Plant oils and oleochemicals derived from them represent such alternative sources, which can deliver a substantial part of what is needed to replace the petroleum used as feedstocks. Plant derived feedstock oils can be provided by two types of oil qualities, multi-purpose and technical oils. Multi-purpose oils represent oil qualities that contain common fatty acids and that can be used for both food and feedstock applications. Technical oil qualities contain unusual fatty acids with special properties gained from their unique molecular structure and these types of oils should only be used for feedstock applications. As a risk mitigation strategy in the selection of crops, technical oil qualities should therefore preferably be produced by oil crop platforms dedicated for industrial usage. This review presents a short survey of oil crop platforms to be considered for either multi-purpose or technical oils production. Included among the former platforms are some of the major oil crops in cultivation such as oil palm, soybean and rapeseed. Among the later are those that could be developed into dedicated industrial platforms such as crambe, flax, cotton and Brassica carinata. The survey finishes off by highlighting the potential of substantial increase in plant oil production by developing metabolic flux platforms, which are starch crops converted into oil crops.

  5. Citrus tristeza virus-based RNAi in citrus plants induces gene silencing in Diaphorina citri, a phloem-sap sucking insect vector of citrus greening disease (Huanglongbing).

    Science.gov (United States)

    Hajeri, Subhas; Killiny, Nabil; El-Mohtar, Choaa; Dawson, William O; Gowda, Siddarame

    2014-04-20

    A transient expression vector based on Citrus tristeza virus (CTV) is unusually stable. Because of its stability it is being considered for use in the field to control Huanglongbing (HLB), which is caused by Candidatus Liberibacter asiaticus (CLas) and vectored by Asian citrus psyllid, Diaphorina citri. In the absence of effective control strategies for CLas, emphasis has been on control of D. citri. Coincident cohabitation in phloem tissue by CLas, D. citri and CTV was exploited to develop a novel method to mitigate HLB through RNA interference (RNAi). Since CTV has three RNA silencing suppressors, it was not known if CTV-based vector could induce RNAi in citrus. Yet, expression of sequences targeting citrus phytoene desaturase gene by CTV-RNAi resulted in photo-bleaching phenotype. CTV-RNAi vector, engineered with truncated abnormal wing disc (Awd) gene of D. citri, induced altered Awd expression when silencing triggers ingested by feeding D. citri nymphs. Decreased Awd in nymphs resulted in malformed-wing phenotype in adults and increased adult mortality. This impaired ability of D. citri to fly would potentially limit the successful vectoring of CLas bacteria between citrus trees in the grove. CTV-RNAi vector would be relevant for fast-track screening of candidate sequences for RNAi-mediated pest control. Copyright © 2014. Published by Elsevier B.V.

  6. Economic Viability of Pumped-Storage Power Plants Equipped with Ternary Units and Considering Hydraulic Short-Circuit Operation

    Science.gov (United States)

    Chazarra, Manuel; Pérez-Díaz, Juan I.; García-González, Javier

    2017-04-01

    This paper analyses the economic viability of pumped-storage hydropower plants equipped with ternary units and considering hydraulic short-circuit operation. The analysed plant is assumed to participate in the day-ahead energy market and in the secondary regulation service of the Spanish power system. A deterministic day-ahead energy and reserve scheduling model is used to estimate the maximum theoretical income of the plant assuming perfect information of the next day prices and the residual demand curves of the secondary regulation reserve market. Results show that the pay-back periods with and without the hydraulic short-circuit operation are significantly lower than their expected lifetime and that the pay-back periods can be reduced with the inclusion of the hydraulic short-circuit operation.

  7. Coat protein mutations in an attenuated Cucumber mosaic virus encoding mutant 2b protein that lacks RNA silencing suppressor activity induces chlorosis with photosynthesis gene repression and chloroplast abnormalities in infected tobacco plants.

    Science.gov (United States)

    Mochizuki, Tomofumi; Yamazaki, Ryota; Wada, Tomoya; Ohki, Satoshi T

    2014-05-01

    In tobacco plants, the Cucumber mosaic virus (CMV) pepo strain induces mosaic symptoms, including pale green chlorosis and malformed tissues. Here, we characterized the involvement of 2b protein and coat protein (CP) in the development of mosaic symptoms. A 2b mutant (R46C) that lacks viral suppressor of RNA silencing (VSR) activity showed an asymptomatic phenotype with low levels of virus accumulation. Tomato spotted wilt virus NSs protein did not complement the virulence of the R46C, although it did restore high-level virus accumulation. However, R46C mutants expressing mutated CP in which the amino acid P129 was mutated to A, E, C, Q, or S induced chlorosis that was associated with reduced expression of chloroplast and photosynthesis related genes (CPRGs) and abnormal chloroplasts with fewer thylakoid membranes. These results suggest that the CP of the CMV pepo strain acquires virulence by amino acid mutations, which causes CPRG repression and chloroplast abnormalities.

  8. The Silence of Michelangelo

    DEFF Research Database (Denmark)

    Foote, Jonathan

    2016-01-01

    's surroundings. As an act that removes us from time by keeping time, the aggregation of metrical sounds from the hidden flesh of materials creates the conditions for working with time, quite literally a contemplation. Michelangelo's astonishment at Moses' subsequent silence was activated by the hammer in an act...... of contemplation with Ovid's well-known myth of Pygmalion. Similarly, while sojourning in the Carrara quarries in 1516, he ignored repeated requests from the pope, friends and family to send a model for the facade of San Lorenzo. The silence from papal politics notwithstanding, it was in fact the hammering...... and distractive, instead activate a contemplative place of silence. Perhaps more than merely a tool for removing stone, the hammer was an instrument for sonorous meditation with materials and thinking....

  9. Gene Expression and Silencing Studies in Phytophthora infestans Reveal Infection-Specific Nutrient Transporters and a Role for the Nitrate Reductase Pathway in Plant Pathogenesis

    Science.gov (United States)

    Ah-Fong, Audrey M. V.; Davis, Carol; Andreeva, Kalina; Judelson, Howard S.

    2016-01-01

    To help learn how phytopathogens feed from their hosts, genes for nutrient transporters from the hemibiotrophic potato and tomato pest Phytophthora infestans were annotated. This identified 453 genes from 19 families. Comparisons with a necrotrophic oomycete, Pythium ultimum var. ultimum, and a hemibiotrophic fungus, Magnaporthe oryzae, revealed diversity in the size of some families although a similar fraction of genes encoded transporters. RNA-seq of infected potato tubers, tomato leaves, and several artificial media revealed that 56 and 207 transporters from P. infestans were significantly up- or down-regulated, respectively, during early infection timepoints of leaves or tubers versus media. About 17 were up-regulated >4-fold in both leaves and tubers compared to media and expressed primarily in the biotrophic stage. The transcription pattern of many genes was host-organ specific. For example, the mRNA level of a nitrate transporter (NRT) was about 100-fold higher during mid-infection in leaves, which are nitrate-rich, than in tubers and three types of artificial media, which are nitrate-poor. The NRT gene is physically linked with genes encoding nitrate reductase (NR) and nitrite reductase (NiR), which mobilize nitrate into ammonium and amino acids. All three genes were coregulated. For example, the three genes were expressed primarily at mid-stage infection timepoints in both potato and tomato leaves, but showed little expression in potato tubers. Transformants down-regulated for all three genes were generated by DNA-directed RNAi, with silencing spreading from the NR target to the flanking NRT and NiR genes. The silenced strains were nonpathogenic on leaves but colonized tubers. We propose that the nitrate assimilation genes play roles both in obtaining nitrogen for amino acid biosynthesis and protecting P. infestans from natural or fertilization-induced nitrate and nitrite toxicity. PMID:27936244

  10. Solar rhythm in the regulation of photoperiodic flowering of long-day and short-day plants.

    Science.gov (United States)

    Yeang, Hoong-Yeet

    2013-07-01

    In photoperiodic flowering, long-day (LD) plants are induced to flower seasonally when the daylight hours are long, whereas flowering in short-day (SD) plants is promoted under short photoperiods. According to the widely accepted external coincidence model, flowering occurs in LD Arabidopsis when the circadian rhythm of the gene CONSTANS (CO) peaks in the afternoon, when it is light during long days but dark when the days are short. Nevertheless, extending this explanation to SD flowering in rice, Oriza sativa, requires LD and SD plants to have 'opposite light requirements' as the CO orthologue in rice, HEADING-DATE1 (Hd1), promotes flowering only under short photoperiods. This report proposes a role of the plant's solar rhythm in promoting seasonal flowering. The interaction between rhythmic genes entrained to the solar clock and those entrained to the circadian clock form the basis of an internal coincidence model that explains both LD and SD flowering equally well. The model invokes no presumption of opposite light requirements between LD and SD plants, and further argues against any specific requirement of either light or darkness for SD flowering. Internal coincidence predicts the inhibition of SD flowering of the rice plant by a night break (a brief interruption of light), while it also provides a plausible explanation for how a judiciously timed night break promotes Arabidopsis flowering even on short days. It is the timing of the light transitions (sunrise and sunset) rather than the duration of light or darkness per se that regulates photoperiod-controlled flowering.

  11. Silêncios Silences

    Directory of Open Access Journals (Sweden)

    Luciano Marcondes Godoy

    1999-01-01

    Full Text Available Muitas são as vivências que se expressarão em SILÊNCIOS. Muitos são os silêncios. No Bloco A, o silêncio denuncia a retirada para um outro mundo, a queda num abismo. No bloco B, o silêncio é controlador, exigindo a fala do analista, um jogo em que o que é falado não tem a menor importância. Surge ainda como expressão da necessidade de discriminar-se do analista e, na sua evolução, como um enfrentamento a um estado sem sentido. No Bloco C, o silêncio é agressivo, e a sobrevivência do analisando e analista ao mesmo criará um espaço que propiciará sonhos que surgirão no Bloco D. Esses momentos de silêncio-sonho são situações em que não há discriminação eu-não eu.Many are the experiences which are expressed through silences. Many are the silences. In Block A, silence denounces a pretreatment to another world, a fall into an abysm. In Block B, silence is a controlling factor, demanding the words of the analyst, a game where what is said does not have any importance what so ever. It emerges also as an expression of the analyst's necessity to discriminate himself, and within his evolution the revision of a senseless state. In Block C, the silence is aggressive. As a response, the survival of the patient and of the analyst will create a place in which dreams will come up. Block D analyses these moments of dream-silence situations, where there aren't any forms of self-non self discrimination.

  12. Antisense gene silencing

    DEFF Research Database (Denmark)

    Nielsen, Troels T; Nielsen, Jørgen E

    2013-01-01

    Since the first reports that double-stranded RNAs can efficiently silence gene expression in C. elegans, the technology of RNA interference (RNAi) has been intensively exploited as an experimental tool to study gene function. With the subsequent discovery that RNAi could also be applied to mammal......Since the first reports that double-stranded RNAs can efficiently silence gene expression in C. elegans, the technology of RNA interference (RNAi) has been intensively exploited as an experimental tool to study gene function. With the subsequent discovery that RNAi could also be applied...

  13. Memories Persist in Silence

    Directory of Open Access Journals (Sweden)

    Sandra Patricia Arenas Grisales

    2012-08-01

    Full Text Available This article exposes the hypothesis that memory artifacts, created to commemorate the victims of armed conflict in Colombia, are an expression of the underground memories and a way of political action in the midst of war. We analyze three cases of creations of memory artifacts in Medellín, Colombia, as forms of suffering, perceiving and resisting the power of armed groups in Medellín. The silence, inherent in these objects, should not be treated as an absence of language, but as another form of expression of memory. Silence is a tactic used to overcome losses and reset everyday life in contexts of protracted violence.

  14. Suppressors of RNA silencing encoded by tomato leaf curl betasatellites

    Indian Academy of Sciences (India)

    Richa Shukla; Sunita Dalal; V G Malathi

    2013-03-01

    Virus encoded RNA-silencing suppressors (RSSs) are the key components evolved by the viruses to counter RNA-silencing defense of plants. Whitefly-transmitted begomoviruses infecting tomato crop code for five different proteins, ORF AC4, ORF AC2 and ORF AV2 in DNA-A component, ORF BV1 in DNA-B and ORF C1 in satellite DNA which are predicted to function as silencing suppressors. In the present study suppressor function of ORF C1 of three betasatellites Tomato leaf curl Bangalore betasatellite ToLCBB-[IN:Hess:08], Cotton leaf curl Multan betasatellite CLCuMB–[IN:Sri:02] and Luffa leaf distortion betasatellite LuLDB-[IN:Lu:04] were examined. Agroinfiltration of GFP-silenced Nicotiana tabaccum cv. Xanthi with the cells expressing C1 protein resulted in reversal of silenced GFP expression. GFP-siRNA level was more than 50-fold lower compared to silenced plants in plants infiltrated with C1 gene from ToLCBB. However, in the case of 35S-C1 CLCuMB and 35S-C1 LuLDB construct, although GFP was expressed, siRNA level was not reduced, indicating that the step at which C1 interfere in RNA-silencing pathway is different.

  15. Suppressors of RNA silencing encoded by tomato leaf curl betasatellites.

    Science.gov (United States)

    Shukla, Richa; Dalal, Sunita; Malathi, V G

    2013-03-01

    Virus encoded RNA-silencing suppressors (RSSs) are the key components evolved by the viruses to counter RNA-silencing defense of plants. Whitefly-transmitted begomoviruses infecting tomato crop code for five different proteins, ORF AC4, ORF AC2 and ORF AV2 in DNA-A component, ORF BV1 in DNA-B and ORF beta C1 in satellite DNA beta which are predicted to function as silencing suppressors. In the present study suppressor function of ORF beta C1 of three betasatellites Tomato leaf curl Bangalore betasatellite ToLCBB-[IN:Hess:08], Cotton leaf curl Multan betasatellite CLCuMB-[IN:Sri:02] and Luffa leaf distortion betasatellite LuLDB-[IN:Lu:04] were examined. Agroinfiltration of GFP-silenced Nicotiana tabaccum cv. Xanthi with the cells expressing betaC1 protein resulted in reversal of silenced GFP expression. GFP-siRNA level was more than 50-fold lower compared to silenced plants in plants infiltrated with betaC1 gene from ToLCBB. However, in the case of 35S-beta C1 CLCuMB and 35S- beta C1 LuLDB construct, although GFP was expressed, siRNA level was not reduced, indicating that the step at which beta C1 interfere in RNA-silencing pathway is different.

  16. Short interspersed elements (SINEs) in plants: origin, classification, and use as phylogenetic markers.

    Science.gov (United States)

    Deragon, Jean-Marc; Zhang, Xiaoyu

    2006-12-01

    Short interspersed elements (SINEs) are a class of dispersed mobile sequences that use RNA as an intermediate in an amplification process called retroposition. The presence-absence of a SINE at a given locus has been used as a meaningful classification criterion to evaluate phylogenetic relations among species. We review here recent developments in the characterisation of plant SINEs and their use as molecular makers to retrace phylogenetic relations among wild and cultivated Oryza and Brassica species. In Brassicaceae, further use of SINE markers is limited by our partial knowledge of endogenous SINE families (their origin and evolution histories) and by the absence of a clear classification. To solve this problem, phylogenetic relations among all known Brassicaceae SINEs were analyzed and a new classification, grouping SINEs in 15 different families, is proposed. The relative age and size of each Brassicaceae SINE family was evaluated and new phylogenetically supported subfamilies were described. We also present evidence suggesting that new potentially active SINEs recently emerged in Brassica oleracea from the shuffling of preexisting SINE portions. Finally, the comparative evolution history of SINE families present in Arabidopsis thaliana and Brassica oleracea revealed that SINEs were in general more active in the Brassica lineage. The importance of these new data for the use of Brassicaceae SINEs as molecular markers in future applications is discussed.

  17. Breaking the Silence

    DEFF Research Database (Denmark)

    Christensen, Tina Dransfeldt

    2017-01-01

    -out interview in 2006. The main focus lies on the question of silence which surrounds homosexuality in Morocco, and its connection with a larger debate about "authentic" Moroccan culture. Then, the article proceeds with an analysis of how Taïa's representational strategies in the public debate have changed...

  18. On Observing Student Silence

    Science.gov (United States)

    Amundrud, Thomas

    2011-01-01

    This article uses conversation analysis (CA) to look at how students in an advanced EGAP (English for general academic purposes) course discussion test create and manage the silence of a group member during the 7-min session. This is combined with a personal narrative inquiry, coinspired by autoethnography, on the author's participation in the…

  19. The Gift of Silence

    Science.gov (United States)

    Haskins, Cathleen

    2011-01-01

    Slowing down, quieting the mind and body, and experiencing silence nourishes the spirit. Montessori educators are mandated to cultivate not just the intellect but the whole child. They recognize that nurturing the spirit of the child is part of what makes this form of education work so well. This article discusses the benefits of stillness and…

  20. Breaking the silence

    DEFF Research Database (Denmark)

    Konradsen, Hanne; Kirkevold, Marit; McCallin, Antoinette

    2012-01-01

    and individual interviews were analyzed using the grounded theory method. The findings revealed that the main concern of the patients was feeling isolated, which was resolved using a process of interactional integration. Interactional integration begins by breaking the silence to enable the progression from...

  1. The Gift of Silence

    Science.gov (United States)

    Haskins, Cathleen

    2011-01-01

    Slowing down, quieting the mind and body, and experiencing silence nourishes the spirit. Montessori educators are mandated to cultivate not just the intellect but the whole child. They recognize that nurturing the spirit of the child is part of what makes this form of education work so well. This article discusses the benefits of stillness and…

  2. Trichodiene production in a Trichoderma harzianum erg1-silenced strain provides evidence of the importance of the sterol biosynthetic pathway in inducing plant defense-related gene expression

    Science.gov (United States)

    Trichoderma species are often used as biocontrol agents against plant-pathogenic fungi. A complex molecular interaction occurs among the biocontrol agent, the antagonistic fungus, and the plant. Terpenes and sterols produced by the biocontrol fungus have been found to affect gene expression in both ...

  3. Progress in molecular mechanism of RNA silencing in plants%植物RNA沉默的分子机制研究进展

    Institute of Scientific and Technical Information of China (English)

    王鹏; 赵显军; 朱国萍

    2008-01-01

    RNA沉默(RNA silencing)是真核生物中的一种抵抗外源遗传因子(病毒、转座子或转基因)及调控基因表达的防御机制.参与植物RNA沉默的酶及蛋白质主要包括6种RNA依赖的RNA聚合酶、4种Dicer-like(DCL)核酸内切酶和10种Argonautes蛋白.植物中4条RNA沉默途径分别由微小RNA(miRNAs)和3种小干扰RNA(siRNAs)介导,包括反式作用siRNAs(ta-siRNAs)、天然反义siRNAs(nat-siRNAs)和异染色质siRNAs(hc-siRNAs).在植物RNA沉默的系统性传播中,由DCL4或DCL2将dsRNAs裁剪为次级siRNAs,以放大RNA沉默信号和增强沉默效应.

  4. The ability of PVX p25 to form RL structures in plant cells is necessary for its function in movement, but not for its suppression of RNA silencing.

    Directory of Open Access Journals (Sweden)

    Fei Yan

    Full Text Available The p25 triple gene block protein of Potato virus X (PVX is multifunctional, participating in viral movement and acting as a suppressor of RNA silencing. The cell-to-cell movement of PVX is known to depend on the suppression function of p25. GFP-fused p25 accumulates in rod-like (RL structures with intense fluorescence in cells. By monitoring the location of fluorescence at different times, we have now shown that the RL structure is composed of filaments. P25 mutants without the conditional ability to recover movement function could not form RL structures while the mutants that had the ability did form the structure, suggesting that the ability of p25 to form RL structures is necessary for its function in cell-to-cell movement, but not for its suppressor function. Moreover, chemical inhibition of microfilaments in cells destroyed the formation of the complete RL structure. Additionally, TGBp2 and TGBp3 were recruited into the RL structure, suggesting a relationship between the TGBps in virus movement.

  5. The ability of PVX p25 to form RL structures in plant cells is necessary for its function in movement, but not for its suppression of RNA silencing.

    Science.gov (United States)

    Yan, Fei; Lu, Yuwen; Lin, Lin; Zheng, Hongying; Chen, Jianping

    2012-01-01

    The p25 triple gene block protein of Potato virus X (PVX) is multifunctional, participating in viral movement and acting as a suppressor of RNA silencing. The cell-to-cell movement of PVX is known to depend on the suppression function of p25. GFP-fused p25 accumulates in rod-like (RL) structures with intense fluorescence in cells. By monitoring the location of fluorescence at different times, we have now shown that the RL structure is composed of filaments. P25 mutants without the conditional ability to recover movement function could not form RL structures while the mutants that had the ability did form the structure, suggesting that the ability of p25 to form RL structures is necessary for its function in cell-to-cell movement, but not for its suppressor function. Moreover, chemical inhibition of microfilaments in cells destroyed the formation of the complete RL structure. Additionally, TGBp2 and TGBp3 were recruited into the RL structure, suggesting a relationship between the TGBps in virus movement.

  6. Silence: a double-edged sword.

    Science.gov (United States)

    Bunkers, Sandra Schmidt

    2013-01-01

    The author in this column discusses the concept silence and the contradictions present with silence. Silence can be experienced in the following life patterns: silence as a pattern of surrendering to moments of awakening; silence as a pattern of bearing witness to life story; and, silence as a pattern of betrayal of trust. Each of these patterns is explored with their relevance for nursing.

  7. Plant Growth under Natural Light Conditions Provides Highly Flexible Short-Term Acclimation Properties toward High Light Stress

    Science.gov (United States)

    Schumann, Tobias; Paul, Suman; Melzer, Michael; Dörmann, Peter; Jahns, Peter

    2017-01-01

    Efficient acclimation to different growth light intensities is essential for plant fitness. So far, most studies on light acclimation have been conducted with plants grown under different constant light regimes, but more recent work indicated that acclimation to fluctuating light or field conditions may result in different physiological properties of plants. Thale cress (Arabidopsis thaliana) was grown under three different constant light intensities (LL: 25 μmol photons m−2 s−1; NL: 100 μmol photons m−2 s−1; HL: 500 μmol photons m−2 s−1) and under natural fluctuating light (NatL) conditions. We performed a thorough characterization of the morphological, physiological, and biochemical properties focusing on photo-protective mechanisms. Our analyses corroborated the known properties of LL, NL, and HL plants. NatL plants, however, were found to combine characteristics of both LL and HL grown plants, leading to efficient and unique light utilization capacities. Strikingly, the high energy dissipation capacity of NatL plants correlated with increased dynamics of thylakoid membrane reorganization upon short-term acclimation to excess light. We conclude that the thylakoid membrane organization and particularly the light-dependent and reversible unstacking of grana membranes likely represent key factors that provide the basis for the high acclimation capacity of NatL grown plants to rapidly changing light intensities. PMID:28515734

  8. Three distinct suppressors of RNA silencing encoded by a 20-kb viral RNA genome

    Science.gov (United States)

    Lu, Rui; Folimonov, Alexey; Shintaku, Michael; Li, Wan-Xiang; Falk, Bryce W.; Dawson, William O.; Ding, Shou-Wei

    2004-11-01

    Viral infection in both plant and invertebrate hosts requires a virus-encoded function to block the RNA silencing antiviral defense. Here, we report the identification and characterization of three distinct suppressors of RNA silencing encoded by the 20-kb plus-strand RNA genome of citrus tristeza virus (CTV). When introduced by genetic crosses into plants carrying a silencing transgene, both p20 and p23, but not coat protein (CP), restored expression of the transgene. Although none of the CTV proteins prevented DNA methylation of the transgene, export of the silencing signal (capable of mediating intercellular silencing spread) was detected only from the F1 plants expressing p23 and not from the CP- or p20-expressing F1 plants, demonstrating suppression of intercellular silencing by CP and p20 but not by p23. Thus, intracellular and intercellular silencing are each targeted by a CTV protein, whereas the third, p20, inhibits silencing at both levels. Notably, CP suppresses intercellular silencing without interfering with intracellular silencing. The novel property of CP suggests a mechanism distinct to p20 and all of the other viral suppressors known to interfere with intercellular silencing and that this class of viral suppressors may not be consistently identified by Agrobacterium coinfiltration because it also induces RNA silencing against the infiltrated suppressor transgene. Our analyses reveal a sophisticated viral counter-defense strategy that targets the silencing antiviral pathway at multiple steps and may be essential for protecting CTV with such a large RNA genome from antiviral silencing in the perennial tree host. RNA interference | citrus tristeza virus | virus synergy | antiviral immunity

  9. Gene silencing: Double-stranded RNA mediated mRNA degradation and gene inactivation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The recent development of gene transfer approaches in plants and animals has revealed that transgene can undergo silencing after integration in the genome. Host genes can also be silenced as a consequence of the presence of a homologous transgene. More and more investigations have demonstrated that doublestranded RNA can silence genes by triggering degradation of homologous RNA in the cytoplasm and by directing methylation of homologous nuclear DNA sequences. Analyses of Arabidopsis mutants and plant viral suppressors of silencing are unraveling RNA-silencing mechanisms and are assessing the role of methylation in transcriptional and posttranscriptional gene silencing. This review will focus on double-stranded RNA mediated mRNA degradation and gene inactivation in plants.

  10. An evaluation of the optimum timing for planting short rotation coppice

    Energy Technology Data Exchange (ETDEWEB)

    Turnbull, D.J.; Jefferies, R.; Parfitt, R.

    2004-07-01

    This report summarises the results of a project to determine the optimum timing for planting, evaluate problems due to late planting in the spring, and to study the planting of willows at different times during the autumn. Details are given of the site installation, previous research on the effect of planting date and storage, and assessment of the establishment and biomass productivity and the viability of cuttings in long-term storage. Charts illustrating biomass productivity are presented, and long-term storage of willow cuttings for autumn planting is discussed.

  11. Silence in Intercultural communication

    Institute of Scientific and Technical Information of China (English)

    Guo Jun

    2012-01-01

    In communication, most of people's attention focuses on verbal communication, nonverbal language as a means of exchange is often ignored. However, nonverbal language continues sending signals, and most of these signals are sent to conversational partners unconsciously. So correct understanding of these signals will help people improve effectiveness of communication. This article will focus on silence, a major part of nonverbal communication, exploring its communicative functions and cultural differences.

  12. Silence in the Communication or Communicating through Silence: Silence in Psychoanalysis

    Directory of Open Access Journals (Sweden)

    Rita Marta

    2014-10-01

    Full Text Available This paper is a reflection upon the meaning and importance of silence in the psychoanalytical relationship. Beginning with the silence in the “normal” relationship between people, we show how silence can be experienced as confortable or unconfortable, and how it can be used to achieve a bigger proximity or distance in the relationship with others. We show these same aspects in the psychoanalytical relationship, and the evolution of the regard towards silence along the development of psychoanalysis. We end, presenting the Nacht’s thinking about silence, who emphasizes its integrative and fundamental role in the psychoanalytical relationship. Thus, only through silence certain affects can be born, and silence allows the patient to internalize the analyst.

  13. Simultaneous silencing of multiple genes in the apple scab fungus, Venturia inaequalis, by expression of RNA with chimeric inverted repeats

    NARCIS (Netherlands)

    Fitzgerald, A.; Kan, van J.A.L.; Plummer, K.M.

    2004-01-01

    RNA-mediated gene silencing has been demonstrated in plants, animals, and more recently in filamentous fungi. Here, we report high frequency, RNA-mediated gene silencing in the apple scab fungus, Venturia inaequalis. The green fluorescent protein (GFP) transgene was silenced in a GFP-expressing tran

  14. Temporal and spatial Bean pod mottle virus-induced gene silencing in soybean.

    Science.gov (United States)

    Juvale, Parijat S; Hewezi, Tarek; Zhang, Chunquan; Kandoth, Pramod Kaitheri; Mitchum, Melissa G; Hill, John H; Whitham, Steven A; Baum, Thomas J

    2012-12-01

    Virus-induced gene silencing (VIGS) is a powerful reverse genetics tool in plant science. In this study, we investigated the temporal and spatial silencing patterns achieved by Bean pod mottle virus (BPMV)-based VIGS in soybean using virus constructs targeting green fluorescence protein (GFP). Silencing GFP enabled an in-depth analysis of silencing in soybean tissues over time in a transgenic line constitutively expressing GFP. We discovered evidence for variable GFP silencing based on insert orientation and targeted region in the coding sequence. A 3' sequence in reverse orientation produced the strongest silencing phenotypes. Furthermore, we documented that BPMV VIGS can achieve widespread silencing in a broad range of tissues, including leaves, stems, flowers and roots. Near-complete silencing was attained in leaves and flowers. Although weaker than in shoots, the observed gene silencing in soybean roots will also allow reverse genetics studies in this tissue. When GFP fluorescence was assayed in cross-sections of stems and leaf petioles, near-complete and uniform silencing was observed in all cell types. Silencing was observed from as early as 2 weeks post-virus inoculation in leaves to 7 weeks post-virus inoculation in flowers, suggesting that this system can induce and maintain silencing for significant durations.

  15. Short-term and continuing stresses differentially interplay with multiple hormones to regulate plant survival and growth.

    Science.gov (United States)

    Yang, Cangjing; Liu, Jingjing; Dong, Xinran; Cai, Zhenying; Tian, Weidong; Wang, Xuelu

    2014-05-01

    The stress phytohormone, abscisic acid (ABA), plays important roles in facilitating plants to survive and grow well under a wide range of stress conditions. Previous gene expression studies mainly focused on plant responses to short-term ABA treatment, but the effect of sustained ABA treatment and their difference are poorly studied. Here, we treated plants with ABA for 1 h or 9 d, and our genome-wide analysis indicated the differentially regulated genes under the two conditions were tremendously different. We analyzed other hormones' signaling changes by using their whole sets of known responsive genes as reporters and integrating feedback regulation of their biosynthesis. We found that, under short-term ABA treatment, signaling outputs of growth-promoting hormones, brassinosteroids and gibberellins, and a biotic stress-responsive hormone, jasmonic acid, were significantly inhibited, while auxin and ethylene signaling outputs were promoted. However, sustained ABA treatment repressed cytokinin and gibberellin signaling, but stimulated auxin signaling. Using several sets of hormone-related mutants, we found candidates in corresponding hormonal signaling pathways, including receptors or transcription regulators, are essential in responding to ABA. Our findings indicate interactions of ABA-dependent stress signals with hormones at different levels are involved in plants to survive under transient stress and to adapt to continuing stressful environments.

  16. Transcriptional silencing of multiple genes in trophozoites of Entamoeba histolytica.

    Directory of Open Access Journals (Sweden)

    Rivka Bracha

    2006-05-01

    Full Text Available In a previous work we described the transcriptional silencing of the amoebapore A (AP-A gene (Ehap-a of Entamoeba histolytica strain HM-1:IMSS. The silencing occurred following transfection with a plasmid containing a 5' upstream region (473 bp of Ehap-a that included a truncated segment (140 bp of a short interspersed nuclear element (SINE1. Silencing remained in effect even after removal of the plasmid (clone G3. Neither short interfering RNA nor methylated DNA were detected, but the chromatin domain of Ehap-a in the gene-silenced trophozoites was modified. Two other similar genes (Ehap-b and one encoding a Saposin-like protein, SAPLIP 1 also became silenced. In the present work we demonstrate the silencing of a second gene of choice, one that encodes the light subunit of the Gal/GalNAc inhibitable lectin (Ehlgl1 and the other, the cysteine proteinase 5 (EhCP-5. This silencing occurred in G3 trophozoites transfected with a plasmid in which the 473 bp 5' upstream Ehap-a fragment was directly ligated to the second gene. Transcriptional silencing occurred in both the transgene and the chromosomal gene. SINE1 sequences were essential, as was a direct connection between the Ehap-a upstream region and the beginning of the open reading frame of the second gene. Gene silencing did not occur in strain HM-1:IMSS with any of these plasmid constructs. The trophozoites with two silenced genes were virulence-attenuated as were those of clone G3. In addition, trophozoites not expressing Lgl1 and AP-A proteins had a significantly reduced ability to cap the Gal/GalNAc-lectin to the uroid region when incubated with antibodies against the heavy (170 kDa subunit of the lectin. Lysates of trophozoites lacking cysteine proteinase 5 and AP-A proteins had 30% less cysteine proteinase activity than those of HM-1:IMSS strain or the G3 clone. Silencing of other genes in G3 amoebae could provide a model to study their various functions. In addition, double gene-silenced

  17. Transcriptional silencing of multiple genes in trophozoites of Entamoeba histolytica.

    Directory of Open Access Journals (Sweden)

    2006-05-01

    Full Text Available In a previous work we described the transcriptional silencing of the amoebapore A (AP-A gene (Ehap-a of Entamoeba histolytica strain HM-1:IMSS. The silencing occurred following transfection with a plasmid containing a 5' upstream region (473 bp of Ehap-a that included a truncated segment (140 bp of a short interspersed nuclear element (SINE1. Silencing remained in effect even after removal of the plasmid (clone G3. Neither short interfering RNA nor methylated DNA were detected, but the chromatin domain of Ehap-a in the gene-silenced trophozoites was modified. Two other similar genes (Ehap-b and one encoding a Saposin-like protein, SAPLIP 1 also became silenced. In the present work we demonstrate the silencing of a second gene of choice, one that encodes the light subunit of the Gal/GalNAc inhibitable lectin (Ehlgl1 and the other, the cysteine proteinase 5 (EhCP-5. This silencing occurred in G3 trophozoites transfected with a plasmid in which the 473 bp 5' upstream Ehap-a fragment was directly ligated to the second gene. Transcriptional silencing occurred in both the transgene and the chromosomal gene. SINE1 sequences were essential, as was a direct connection between the Ehap-a upstream region and the beginning of the open reading frame of the second gene. Gene silencing did not occur in strain HM-1:IMSS with any of these plasmid constructs. The trophozoites with two silenced genes were virulence-attenuated as were those of clone G3. In addition, trophozoites not expressing Lgl1 and AP-A proteins had a significantly reduced ability to cap the Gal/GalNAc-lectin to the uroid region when incubated with antibodies against the heavy (170 kDa subunit of the lectin. Lysates of trophozoites lacking cysteine proteinase 5 and AP-A proteins had 30% less cysteine proteinase activity than those of HM-1:IMSS strain or the G3 clone. Silencing of other genes in G3 amoebae could provide a model to study their various functions. In addition, double gene-silenced

  18. Plants, Birds and Butterflies: Short-Term Responses of Species Communities to Climate Warming Vary by Taxon and with Altitude

    Science.gov (United States)

    Roth, Tobias; Plattner, Matthias; Amrhein, Valentin

    2014-01-01

    As a consequence of climate warming, species usually shift their distribution towards higher latitudes or altitudes. Yet, it is unclear how different taxonomic groups may respond to climate warming over larger altitudinal ranges. Here, we used data from the national biodiversity monitoring program of Switzerland, collected over an altitudinal range of 2500 m. Within the short period of eight years (2003–2010), we found significant shifts in communities of vascular plants, butterflies and birds. At low altitudes, communities of all species groups changed towards warm-dwelling species, corresponding to an average uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of community changes decreased with altitude in plants and butterflies, while bird communities changed towards warm-dwelling species at all altitudes. We found no decrease in community variation with respect to temperature niches of species, suggesting that climate warming has not led to more homogenous communities. The different community changes depending on altitude could not be explained by different changes of air temperatures, since during the 16 years between 1995 and 2010, summer temperatures in Switzerland rose by about 0.07°C per year at all altitudes. We discuss that land-use changes or increased disturbances may have prevented alpine plant and butterfly communities from changing towards warm-dwelling species. However, the findings are also consistent with the hypothesis that unlike birds, many alpine plant species in a warming climate could find suitable habitats within just a few metres, due to the highly varied surface of alpine landscapes. Our results may thus support the idea that for plants and butterflies and on a short temporal scale, alpine landscapes are safer places than lowlands in a warming world. PMID:24416144

  19. Plants, birds and butterflies: short-term responses of species communities to climate warming vary by taxon and with altitude.

    Directory of Open Access Journals (Sweden)

    Tobias Roth

    Full Text Available As a consequence of climate warming, species usually shift their distribution towards higher latitudes or altitudes. Yet, it is unclear how different taxonomic groups may respond to climate warming over larger altitudinal ranges. Here, we used data from the national biodiversity monitoring program of Switzerland, collected over an altitudinal range of 2500 m. Within the short period of eight years (2003-2010, we found significant shifts in communities of vascular plants, butterflies and birds. At low altitudes, communities of all species groups changed towards warm-dwelling species, corresponding to an average uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of community changes decreased with altitude in plants and butterflies, while bird communities changed towards warm-dwelling species at all altitudes. We found no decrease in community variation with respect to temperature niches of species, suggesting that climate warming has not led to more homogenous communities. The different community changes depending on altitude could not be explained by different changes of air temperatures, since during the 16 years between 1995 and 2010, summer temperatures in Switzerland rose by about 0.07°C per year at all altitudes. We discuss that land-use changes or increased disturbances may have prevented alpine plant and butterfly communities from changing towards warm-dwelling species. However, the findings are also consistent with the hypothesis that unlike birds, many alpine plant species in a warming climate could find suitable habitats within just a few metres, due to the highly varied surface of alpine landscapes. Our results may thus support the idea that for plants and butterflies and on a short temporal scale, alpine landscapes are safer places than lowlands in a warming world.

  20. Plants, birds and butterflies: short-term responses of species communities to climate warming vary by taxon and with altitude.

    Science.gov (United States)

    Roth, Tobias; Plattner, Matthias; Amrhein, Valentin

    2014-01-01

    As a consequence of climate warming, species usually shift their distribution towards higher latitudes or altitudes. Yet, it is unclear how different taxonomic groups may respond to climate warming over larger altitudinal ranges. Here, we used data from the national biodiversity monitoring program of Switzerland, collected over an altitudinal range of 2500 m. Within the short period of eight years (2003-2010), we found significant shifts in communities of vascular plants, butterflies and birds. At low altitudes, communities of all species groups changed towards warm-dwelling species, corresponding to an average uphill shift of 8 m, 38 m and 42 m in plant, butterfly and bird communities, respectively. However, rates of community changes decreased with altitude in plants and butterflies, while bird communities changed towards warm-dwelling species at all altitudes. We found no decrease in community variation with respect to temperature niches of species, suggesting that climate warming has not led to more homogenous communities. The different community changes depending on altitude could not be explained by different changes of air temperatures, since during the 16 years between 1995 and 2010, summer temperatures in Switzerland rose by about 0.07°C per year at all altitudes. We discuss that land-use changes or increased disturbances may have prevented alpine plant and butterfly communities from changing towards warm-dwelling species. However, the findings are also consistent with the hypothesis that unlike birds, many alpine plant species in a warming climate could find suitable habitats within just a few metres, due to the highly varied surface of alpine landscapes. Our results may thus support the idea that for plants and butterflies and on a short temporal scale, alpine landscapes are safer places than lowlands in a warming world.

  1. 靶向CCR7基因shRNA表达载体的构建及鉴定%Construction and identification of pGC-silencer-CRM30 CCR7 short hairpin RNA expression vectors

    Institute of Scientific and Technical Information of China (English)

    孙仁虎; 李疆; 崔静; 吕清; 刘兴华; 王国斌

    2009-01-01

    目的 设计并构建靶向 CCR7 基因 shRNA真核表达质粒,并检测其干扰效果.方法 以 CCR7 为靶基因设计具有短发夹结构的模板寡核苷酸,退火形成互补双链结构,再克隆至pGC-silencer-CRM30 载体,构建的3条重组短发夹shRNA表达载体分别命名为pGC-silencer-CRM30-CCR7 A、-CCR7 B 和-CCR7 C.采用测序法鉴定寡核苷酸序列.将构建好的真核表达载体转染人结肠癌SW480 细胞,荧光显微镜观察转染效果,RT-PCR法检测CCR7干扰效率.结果 重组质粒测序结果 与Genebank中的CCR7 cDNA序列相符,转染SW480细胞后,荧光显微镜下可观察到绿色荧光蛋白,RT-PCR结果 表明,pGC-silencer-CRM30-CCR7 C干扰效果最强.结论 靶向CCR7 基因shRNA表达载体构建无误,为进一步探讨趋化因子受体CCR7在胃肠道恶性肿瘤生物学行为中的作用奠定了基础.

  2. Rethinking the Day of Silence

    Science.gov (United States)

    Murphy, Adriana

    2013-01-01

    Back in 2006, 7th and 8th graders at Green Acres, the K-8 independent school where the author taught in suburban Maryland, participated in the Day of Silence. The Day of Silence is a national event: Students across the country take a one-day pledge of silence to show that they want to make schools safe for all students, regardless of their sexual…

  3. Voice and silence in organizations

    Directory of Open Access Journals (Sweden)

    Moaşa, H.

    2011-01-01

    Full Text Available Unlike previous research on voice and silence, this article breaksthe distance between the two and declines to treat them as opposites. Voice and silence are interrelated and intertwined strategic forms ofcommunication which presuppose each other in such a way that the absence of one would minimize completely the other’s presence. Social actors are not voice, or silence. Social actors can have voice or silence, they can do both because they operate at multiple levels and deal with multiple issues at different moments in time.

  4. Antisense gene silencing

    DEFF Research Database (Denmark)

    Nielsen, Troels T; Nielsen, Jørgen E

    2013-01-01

    Since the first reports that double-stranded RNAs can efficiently silence gene expression in C. elegans, the technology of RNA interference (RNAi) has been intensively exploited as an experimental tool to study gene function. With the subsequent discovery that RNAi could also be applied...... to mammalian cells, the technology of RNAi expanded from being a valuable experimental tool to being an applicable method for gene-specific therapeutic regulation, and much effort has been put into further refinement of the technique. This review will focus on how RNAi has developed over the years and how...

  5. Mobile gene silencing in Arabidopsis is regulated by hydrogen peroxide

    Directory of Open Access Journals (Sweden)

    Dacheng Liang

    2014-12-01

    Full Text Available In plants and nematodes, RNAi can spread from cells from which it is initiated to other cells in the organism. The underlying mechanism controlling the mobility of RNAi signals is not known, especially in the case of plants. A genetic screen designed to recover plants impaired in the movement but not the production or effectiveness of the RNAi signal identified RCI3, which encodes a hydrogen peroxide (H2O2-producing type III peroxidase, as a key regulator of silencing mobility in Arabidopsis thaliana. Silencing initiated in the roots of rci3 plants failed to spread into leaf tissue or floral tissue. Application of exogenous H2O2 reinstated the spread in rci3 plants and accelerated it in wild-type plants. The addition of catalase or MnO2, which breaks down H2O2, slowed the spread of silencing in wild-type plants. We propose that endogenous H2O2, under the control of peroxidases, regulates the spread of gene silencing by altering plasmodesmata permeability through remodelling of local cell wall structure, and may play a role in regulating systemic viral defence.

  6. Gene Silence ofPhytophthora infestans Induced by Plant-mediated RNA Inter-ference in Potato%植物介导的RNA干扰引起马铃薯晚疫病菌基因的沉默

    Institute of Scientific and Technical Information of China (English)

    任琴; 王亚军; 郭志鸿; 李继平; 谢忠奎; 王若愚; 王立; 惠娜娜

    2015-01-01

    由致病疫霉(Phytophthora infestans)引起的晚疫病是最具毁灭性的马铃薯病害。为明确植物介导的RNAi沉默致病疫霉基因的有效性,本研究采用重叠延伸PCR技术克隆同时与晚疫病菌4个ces基因均同源的融合基因C1234,构建内含子连接的C1234反向重复序列植物表达载体,采用农杆菌介导法转化晚疫病易感马铃薯品种大西洋,经PCR和Southern杂交检测,获得129个转基因株系。离体叶片接种病原菌后,有97个转基因株系发病速度明显慢于野生型,接种6 d后病斑大小和霉层厚度均明显小于对照,并且叶片感病部位没有出现失绿斑,而野生型产生了明显的失绿斑。实时定量RT-PCR分析发现,发病延缓的叶片上致病疫霉4个纤维素合酶基因的表达水平明显低于野生型。本研究表明,转基因植株中产生的以晚疫病菌ces基因为靶标的dsRNA能够沉默致病疫霉相应基因表达,延缓发病进程。%Potato late blightcaused by Phytophthora infestans is the most devastating disease in potato. The objective of this study was to test the efficiency of plant-meidated RNAi in silencing genes in P. infestans and to find a new way to breed potato resistant to late blight. Over-lap PCR was employed to amplify a fused-geneC1234 simultaneously homologous to four cellulose synthase genes inP. infenstans. Then, a plant expression vector containing inverted repeat ofC1234was constructed and transferred to Atlantic, a potato variety severely susceptible to late blight by agrobacteria-mediated genetic transformation. A hundred and twenty nine regenerated lines were confirmed to be transgenic plants with PCR and Southern blot. When detached leaves were inoculated withP. infestans, 97 out of 129 transgenic lines delayed disease symptoms with smaller lesions and less hyphae com-pared to the wild type at six days after inoculation. Chlorotic spots did not appeared on leaves from transgenic lines while deve

  7. "Listening Silence" and Its Discursive Effects

    Science.gov (United States)

    Applebaum, Barbara

    2016-01-01

    While researchers have studied how white silence protects white innocence and white ignorance, in this essay Barbara Applebaum explores a form of white silence that she refers to as "listening silence" in which silence protects white innocence but does not necessarily promote resistance to learning. White listening silence can appear to…

  8. Dissecting plant iron homeostasis under short and long-term iron fluctuations

    DEFF Research Database (Denmark)

    Shirvanehdeh, Behrooz Darbani; Briat, Jean-Francois; Holm, Preben Bach;

    2013-01-01

    A wealth of information on the different aspects of iron homeostasis in plants has been obtained during the last decade. However, there is no clear road-map integrating the relationships between the various components. The principal aim of the current review is to fill this gap. In this context we...... discuss the lack of low affinity iron uptake mechanisms in plants, the utilization of a different uptake mechanism by graminaceous plants compared to the others, as well as the roles of riboflavin, ferritin isoforms, nitric oxide, nitrosylation, heme, aconitase, and vacuolar pH. Cross-homeostasis between...... elements is also considered, with a specific emphasis on the relationship between iron homeostasis and phosphorus and copper deficiencies. As the environment is a crucial parameter for modulating plant responses, we also highlight how diurnal fluctuations govern iron metabolism. Evolutionary aspects...

  9. Bioindication: a short review on the use of plants as indicators of heavy metals.

    Science.gov (United States)

    Kovács, M; Podani, J

    1986-01-01

    This paper discusses some fundamental principles of bioindication. The presentation follows a classification of methods based on the different levels of organization implied in the various approaches. Special references are made to plants that accumulate heavy metals.

  10. Bodies, Spaces, Voices, Silences

    Directory of Open Access Journals (Sweden)

    Donatella Mazzoleni

    2013-07-01

    Full Text Available A good architecture should not only allow functional, formal and technical quality for urban spaces, but also let the voice of the city be perceived, listened, enjoyed. Every city has got its specific sound identity, or “ISO” (R. O. Benenzon, made up of a complex texture of background noises and fluctuation of sound figures emerging and disappearing in a game of continuous fadings. For instance, the ISO of Naples is characterized by a spread need of hearing the sound return of one’s/others voices, by a hate of silence. Cities may fall ill: illness from noise, within super-crowded neighbourhoods, or illness from silence, in the forced isolation of peripheries. The proposal of an urban music therapy denotes an unpublished and innovative enlarged interdisciplinary research path, where architecture, music, medicine, psychology, communication science may converge, in order to work for rebalancing spaces and relation life of the urban collectivity, through the care of body and sound dimensions.

  11. A mathematical model of non-photochemical quenching to study short-term light memory in plants.

    Science.gov (United States)

    Matuszyńska, Anna; Heidari, Somayyeh; Jahns, Peter; Ebenhöh, Oliver

    2016-12-01

    Plants are permanently exposed to rapidly changing environments, therefore it is evident that they had to evolve mechanisms enabling them to dynamically adapt to such fluctuations. Here we study how plants can be trained to enhance their photoprotection and elaborate on the concept of the short-term illumination memory in Arabidopsis thaliana. By monitoring fluorescence emission dynamics we systematically observe the extent of non-photochemical quenching (NPQ) after previous light exposure to recognise and quantify the memory effect. We propose a simplified mathematical model of photosynthesis that includes the key components required for NPQ activation, which allows us to quantify the contribution to photoprotection by those components. Due to its reduced complexity, our model can be easily applied to study similar behavioural changes in other species, which we demonstrate by adapting it to the shadow-tolerant plant Epipremnum aureum. Our results indicate that a basic mechanism of short-term light memory is preserved. The slow component, accumulation of zeaxanthin, accounts for the amount of memory remaining after relaxation in darkness, while the fast one, antenna protonation, increases quenching efficiency. With our combined theoretical and experimental approach we provide a unifying framework describing common principles of key photoprotective mechanisms across species in general, mathematical terms.

  12. Functional analysis of soybean genes involved in flavonoid biosynthesis by virus-induced gene silencing.

    Science.gov (United States)

    Nagamatsu, Atsushi; Masuta, Chikara; Senda, Mineo; Matsuura, Hideyuki; Kasai, Atsushi; Hong, Jin-Sung; Kitamura, Keisuke; Abe, Jun; Kanazawa, Akira

    2007-11-01

    Virus-induced gene silencing (VIGS) is a powerful tool for functional analysis of genes in plants. A wide-host-range VIGS vector, which was developed based on the Cucumber mosaic virus (CMV), was tested for its ability to silence endogenous genes involved in flavonoid biosynthesis in soybean. Symptomless infection was established using a pseudorecombinant virus, which enabled detection of specific changes in metabolite content by VIGS. It has been demonstrated that the yellow seed coat phenotype of various cultivated soybean lines that lack anthocyanin pigmentation is induced by natural degradation of chalcone synthase (CHS) mRNA. When soybean plants with brown seed coats were infected with a virus that contains the CHS gene sequence, the colour of the seed coats changed to yellow, which indicates that the naturally occurring RNA silencing is reproduced by VIGS. In addition, CHS VIGS consequently led to a decrease in isoflavone content in seeds. VIGS was also tested on the putative flavonoid 3'-hydroxylase (F3'H) gene in the pathway. This experiment resulted in a decrease in the content of quercetin relative to kaempferol in the upper leaves after viral infection, which suggests that the putative gene actually encodes the F3'H protein. In both experiments, a marked decrease in the target mRNA and accumulation of short interfering RNAs were detected, indicating that sequence-specific mRNA degradation was induced. The present report is a successful demonstration of the application of VIGS for genes involved in flavonoid biosynthesis in plants; the CMV-based VIGS system provides an efficient tool for functional analysis of soybean genes.

  13. Organizational Silence in Sports Employees

    Science.gov (United States)

    Bastug, Gulsum; Pala, Adem; Yilmaz, Taner; Duyan, Mehdi; Gunel, Ilker

    2016-01-01

    Organizational silence can be defined as a way of behaviour belonging to men and women employees in the organization exhibited without reflecting their feelings, ideas, concerns and suggestions related with their workplaces, works for which they are responsible or other activities of the organization. In the period of organizational silence,…

  14. Silence, an Eye of Knowledge

    Science.gov (United States)

    Aghamohammadi, Mehdi

    2017-01-01

    One of the conspicuous features of the twentieth-century West was silence. This idea could be supported by examining reflections of Ludwig Wittgenstein, Fritz Mauthner, John Cage, Samuel Beckett, Ihab Hassan, Franz Kafka, Wassily Kandinsky, Jean-Paul Sartre, Virginia Woolf, Wolfgang Iser, Jacques Derrida, and Pierre Macherey. To me, silence is not…

  15. Respective contributions of Arabidopsis DCL2 and DCL4 to RNA silencing.

    Science.gov (United States)

    Parent, Jean-Sébastien; Bouteiller, Nathalie; Elmayan, Taline; Vaucheret, Hervé

    2015-01-01

    Dicer proteins are central to the different mechanisms involving RNA interference. Plants have evolved multiple DICER-LIKE (DCL) copies, thus enabling functional diversification. In Arabidopsis, DCL2 and DCL4 process double-stranded RNA into 22 and 21 nucleotide small interfering (si)RNAs, respectively, and have overlapping functions with regards to virus and transgene silencing. Nonetheless, some studies have reported that dcl2 or dcl4 single mutations are sometimes sufficient to hinder silencing. To better dissect the role of DCL2 and DCL4, we analyzed silencing kinetics and efficiencies using different transgenic systems in single and double mutant backgrounds. The results indicate that DCL2 stimulates transitivity and secondary siRNA production through DCL4 while being sufficient for silencing on its own. Notably, silencing of 35S-driven transgenes functions more efficiently in dcl4 mutants, indicating that DCL4 mostly obscures DCL2 in wild-type plants. Nonetheless, in a dcl4 mutant compromised in phloem-originating silencing, ectopically expressed DCL2 allows restoration of silencing, suggesting that DCL2 is not, or poorly, expressed in phloem. Remarkably, this ectopic DCL2 contribution to phloem-originating silencing is dependent on the activity of RNA-DEPENDENT RNA POLYMERASE6. These results indicate that, despite differences in the silencing activity of their small RNA products, DCL2 and DCL4 mostly act redundantly yet hierarchically when present simultaneously. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

  16. Viral RNA silencing suppression

    NARCIS (Netherlands)

    Hedil, Marcio; Kormelink, Richard

    2016-01-01

    The Bunyaviridae is a family of arboviruses including both plant-and vertebrate-infecting representatives. The Tospovirus genus accommodates plant-infecting bunyaviruses, which not only replicate in their plant host, but also in their insect thrips vector during persistent propagative transmissio

  17. Quick Measurement of CH4, CO2 and N2O Emissions from a Short-Plant Ecosystem

    Institute of Scientific and Technical Information of China (English)

    王跃思; 王迎红

    2003-01-01

    Combining improved injector, gas line and valve-driving models, a gas chromatograph (GC) equippedwith Hydrogen Flame Ionization Detector (FID) and Electron Capture Detector (ECD), can measureCH4, CO2, and N2O simultaneously in an air sample in four minutes. Test results show that the systemhas high sensitivity, resolution, and precision; the linear response range of the system meets the requirementof flux measurements in situ. The system is suitable for monitoring fluxes of the main greenhouse gases ina short-plant field since it is easy to use, efficacious, and constant and reliable in collecting data.

  18. Local-scale and short-term herbivore-plant spatial dynamics reflect influences of large-scale climate

    DEFF Research Database (Denmark)

    Forchhammer, Mads Cedergreen; Post, Eric; Berg, Thomas B. G.

    2005-01-01

    The balance of evidence strongly indicates that the ecological repercussions of climatic changes are already apparent in the dynamics of animal and plant populations throughout terrestrial, marine, and aquatic ecosystems. However, while considerable progress has been made in quantifying effects...... of climate change for population and community dynamics. Using comprehensive, spatially replicated data on seasonal plant growth dynamics and seasonal distribution of muskoxen over a seven-year period, we show that interannual variations in the North Atlantic Oscillation affect the seasonal spatial dynamics...... of such climate change on spatiotemporal shifts in distribution, density, and phenology, subtle effects such as intra-annual variation in behavior have been ignored. Yet individual-based assessments of short-term dynamics of species interactions may be critical to improving our understanding of the implications...

  19. Tall or short? Slender or thick? A plant strategy for regulating elongation growth of roots by low concentrations of gibberellin.

    Science.gov (United States)

    Tanimoto, Eiichi

    2012-07-01

    Since the plant hormone gibberellin (GA) was discovered as a fungal toxin that caused abnormal elongation of rice shoots, the physiological function of GA has mainly been investigated in relation to the regulation of plant height. However, an indispensable role for GA in root growth has been elucidated by using severely GA-depleted plants, either with a gene mutation in GA biosynthesis or which have been treated by an inhibitor of GA biosynthesis. The molecular sequence of GA signalling has also been studied to understand GA functions in root growth. This review addresses research progress on the physiological functions of GA in root growth. Concentration-dependent stimulation of elongation growth by GA is important for the regulation of plant height and root length. Thus the endogenous level of GA and/or the GA sensitivity of shoots and roots plays a role in determining the shoot-to-root ratio of the plant body. Since the shoot-to-root ratio is an important parameter for agricultural production, control of GA production and GA sensitivity may provide a strategy for improving agricultural productivity. The sequence of GA signal transduction has recently been unveiled, and some component molecules are suggested as candidate in planta regulatory sites and as points for the artificial manipulation of GA-mediated growth control. This paper reviews: (1) the breakthrough dose-response experiments that show that root growth is regulated by GA in a lower concentration range than is required for shoot growth; (2) research on the regulation of GA biosynthesis pathways that are known predominantly to control shoot growth; and (3) recent research on GA signalling pathways, including GA receptors, which have been suggested to participate in GA-mediated growth regulation. This provides useful information to suggest a possible strategy for the selective control of shoot and root growth, and to explain how GA plays a role in rosette and liana plants with tall or short, and slender

  20. Models for the physiological effects of short O3 exposures on plants

    NARCIS (Netherlands)

    Schut, H.E.

    1985-01-01

    Some published effects of ozone on plant photosynthesis and evaporation are detailed, and attempts were made to develop explanatory models of increasing complexity. Stomatal regulation, which keeps the CO2 concentration inside the lead constant, is assumed. The O3 concentration inside the leaf is as

  1. Short communication: an in vitro assessment of the antibacterial activity of plant-derived oils.

    Science.gov (United States)

    Mullen, K A E; Lee, A R; Lyman, R L; Mason, S E; Washburn, S P; Anderson, K L

    2014-09-01

    Nonantibiotic treatments for mastitis are needed in organic dairy herds. Plant-derived oils may be useful but efficacy and potential mechanisms of action of such oils in mastitis therapy have not been well documented. The objective of the current study was to evaluate the antibacterial activity of the plant-derived oil components of Phyto-Mast (Bovinity Health LLC, Narvon, PA), an herbal intramammary product, against 3 mastitis-causing pathogens: Staphylococcus aureus, Staphylococcus chromogenes, and Streptococcus uberis. Plant-derived oils evaluated were Thymus vulgaris (thyme), Gaultheria procumbens (wintergreen), Glycyrrhiza uralensis (Chinese licorice), Angelica sinensis, and Angelica dahurica. Broth dilution testing according to standard protocol was performed using ultrapasteurized whole milk instead of broth. Controls included milk only (negative control), milk + bacteria (positive control), and milk + bacteria + penicillin-streptomycin (antibiotic control, at 1 and 5% concentrations). Essential oil of thyme was tested by itself and not in combination with other oils because of its known antibacterial activity. The other plant-derived oils were tested alone and in combination for a total of 15 treatments, each replicated 3 times and tested at 0.5, 1, 2, and 4% to simulate concentrations potentially achievable in the milk within the pre-dry-off udder quarter. Thyme oil at concentrations ≥2% completely inhibited bacterial growth in all replications. Other plant-derived oils tested alone or in various combinations were not consistently antibacterial and did not show typical dose-response effects. Only thyme essential oil had consistent antibacterial activity against the 3 mastitis-causing organisms tested in vitro. Further evaluation of physiological effects of thyme oil in various preparations on mammary tissue is recommended to determine potential suitability for mastitis therapy. Copyright © 2014 American Dairy Science Association. Published by Elsevier

  2. Repeat-induced gene silencing in mammals.

    Science.gov (United States)

    Garrick, D; Fiering, S; Martin, D I; Whitelaw, E

    1998-01-01

    In both plants and Drosophila melanogaster, expression from a transgenic locus may be silenced when repeated transgene copies are arranged as a concatameric array. This repeat-induced gene silencing is frequently manifested as a decrease in the proportion of cells that express the transgene, resulting in a variegated pattern of expression. There is also some indication that, in transgenic mammals, the number of transgene copies within an array can exert a repressive influence on expression, with several mouse studies reporting a decrease in the level of expression per copy as copy number increases. However, because these studies compare different sites of transgene integration as well as arrays with different numbers of copies, the expression levels observed may be subject to varying position effects as well as the influence of the multicopy array. Here we describe use of the lox/Cre system of site-specific recombination to generate transgenic mouse lines in which different numbers of a transgene are present at the same chromosomal location, thereby eliminating the contribution of position effects and allowing analysis of the effect of copy number alone on transgene silencing. Reduction in copy number results in a marked increase in expression of the transgene and is accompanied by decreased chromatin compaction and decreased methylation at the transgene locus. These findings establish that the presence of multiple homologous copies of a transgene within a concatameric array can have a repressive effect upon gene expression in mammalian systems.

  3. The effects of short- and long-term air pollutants on plant phenology and leaf characteristics.

    Science.gov (United States)

    Jochner, Susanne; Markevych, Iana; Beck, Isabelle; Traidl-Hoffmann, Claudia; Heinrich, Joachim; Menzel, Annette

    2015-11-01

    Pollution adversely affects vegetation; however, its impact on phenology and leaf morphology is not satisfactorily understood yet. We analyzed associations between pollutants and phenological data of birch, hazel and horse chestnut in Munich (2010) along with the suitability of leaf morphological parameters of birch for monitoring air pollution using two datasets: cumulated atmospheric concentrations of nitrogen dioxide and ozone derived from passive sampling (short-term exposure) and pollutant information derived from Land Use Regression models (long-term exposure). Partial correlations and stepwise regressions revealed that increased ozone (birch, horse chestnut), NO2, NOx and PM levels (hazel) were significantly related to delays in phenology. Correlations were especially high when rural sites were excluded suggesting a better estimation of long-term within-city pollution. In situ measurements of foliar characteristics of birch were not suitable for bio-monitoring pollution. Inconsistencies between long- and short-term exposure effects suggest some caution when interpreting short-term data collected within field studies.

  4. Viral RNA Silencing Suppression: The Enigma of Bunyavirus NSs Proteins

    Directory of Open Access Journals (Sweden)

    Marcio Hedil

    2016-07-01

    Full Text Available The Bunyaviridae is a family of arboviruses including both plant- and vertebrate-infecting representatives. The Tospovirus genus accommodates plant-infecting bunyaviruses, which not only replicate in their plant host, but also in their insect thrips vector during persistent propagative transmission. For this reason, they are generally assumed to encounter antiviral RNA silencing in plants and insects. Here we present an overview on how tospovirus nonstructural NSs protein counteracts antiviral RNA silencing in plants and what is known so far in insects. Like tospoviruses, members of the related vertebrate-infecting bunyaviruses classified in the genera Orthobunyavirus, Hantavirus and Phlebovirus also code for a NSs protein. However, for none of them RNA silencing suppressor activity has been unambiguously demonstrated in neither vertebrate host nor arthropod vector. The second part of this review will briefly describe the role of these NSs proteins in modulation of innate immune responses in mammals and elaborate on a hypothetical scenario to explain if and how NSs proteins from vertebrate-infecting bunyaviruses affect RNA silencing. If so, why this discovery has been hampered so far.

  5. Caveat of RNAi in plants: the off-target effect.

    Science.gov (United States)

    Senthil-Kumar, Muthappa; Mysore, Kirankumar S

    2011-01-01

    RNA interference (RNAi), mediated by short interfering RNAs (siRNAs), is one of the widely used functional genomics method for suppressing the gene expression in plants. Initially, gene silencing by RNAi mechanism was believed to be specific requiring sequence homology between siRNA and target mRNA. However, several recent reports have showed that non-specific effects often referred as off-target gene silencing can occur during RNAi. This unintended gene silencing can lead to false conclusions in RNAi experiments that are aimed to study the functional role of a particular target gene in plants. This especially is a major problem in large-scale RNAi-based screens aiming for gene discovery. Hence, understanding the off-target effects is crucial for minimizing such effects to better conclude gene function analyzed by RNAi. We discuss here potential problems of off-target gene silencing and focus on possibilities that favor this effect during post-transcriptional gene silencing. Suggestions to overcome the off-target effects during RNAi studies are also presented. We believe that information available in present-day plant science literature about specificity of siRNA actions is inadequate. In-depth systematic studies to understand their molecular basis are necessary to enable improved design of more specific RNAi vectors. In the meantime, gene function and phenotype results from present-day RNAi studies need to be interpreted with caution.

  6. Plant Mobile Small RNAs

    OpenAIRE

    Dunoyer, Patrice; Melnyk, Charles; Molnar, Attila; Slotkin, R Keith

    2013-01-01

    In plants, RNA silencing is a fundamental regulator of gene expression, heterochromatin formation, suppression of transposable elements, and defense against viruses. The sequence specificity of these processes relies on small noncoding RNA (sRNA) molecules. Although the spreading of RNA silencing across the plant has been recognized for nearly two decades, only recently have sRNAs been formally demonstrated as the mobile silencing signals. Here, we discuss the various types of mobile sRNA mol...

  7. Homoeologous gene silencing in tissue cultured wheat callus

    Directory of Open Access Journals (Sweden)

    Chapman Natalie H

    2008-10-01

    Full Text Available Abstract Background In contrast to diploids, most polyploid plant species, which include the hexaploid bread wheat, possess an additional layer of epigenetic complexity. Several studies have demonstrated that polyploids are affected by homoeologous gene silencing, a process in which sub-genomic genomic copies are selectively transcriptionally inactivated. This form of silencing can be tissue specific and may be linked to developmental or stress responses. Results Evidence was sought as to whether the frequency of homoeologous silencing in in vitro cultured wheat callus differ from that in differentiated organs, given that disorganized cells are associated with a globally lower level of DNA methylation. Using a reverse transcription PCR (RT-PCR single strand conformation polymorphism (SSCP platform to detect the pattern of expression of 20 homoeologous sets of single-copy genes known to be affected by this form of silencing in the root and/or leaf, we observed no silencing in any of the wheat callus tissue tested. Conclusion Our results suggest that much of the homoeologous silencing observed in differentiated tissues is probably under epigenetic control, rather than being linked to genomic instability arising from allopolyploidization. This study reinforces the notion of plasticity in the wheat epi-genome.

  8. Targeted identification of short interspersed nuclear element families shows their widespread existence and extreme heterogeneity in plant genomes.

    Science.gov (United States)

    Wenke, Torsten; Döbel, Thomas; Sörensen, Thomas Rosleff; Junghans, Holger; Weisshaar, Bernd; Schmidt, Thomas

    2011-09-01

    Short interspersed nuclear elements (SINEs) are non-long terminal repeat retrotransposons that are highly abundant, heterogeneous, and mostly not annotated in eukaryotic genomes. We developed a tool designated SINE-Finder for the targeted discovery of tRNA-derived SINEs. We analyzed sequence data of 16 plant genomes, including 13 angiosperms and three gymnosperms and identified 17,829 full-length and truncated SINEs falling into 31 families showing the widespread occurrence of SINEs in higher plants. The investigation focused on potato (Solanum tuberosum), resulting in the detection of seven different SolS SINE families consisting of 1489 full-length and 870 5' truncated copies. Consensus sequences of full-length members range in size from 106 to 244 bp depending on the SINE family. SolS SINEs populated related species and evolved separately, which led to some distinct subfamilies. Solanaceae SINEs are dispersed along chromosomes and distributed without clustering but with preferred integration into short A-rich motifs. They emerged more than 23 million years ago and were species specifically amplified during the radiation of potato, tomato (Solanum lycopersicum), and tobacco (Nicotiana tabacum). We show that tobacco TS retrotransposons are composite SINEs consisting of the 3' end of a long interspersed nuclear element integrated downstream of a nonhomologous SINE family followed by successfully colonization of the genome. We propose an evolutionary scenario for the formation of TS as a spontaneous event, which could be typical for the emergence of SINE families.

  9. Targeted Identification of Short Interspersed Nuclear Element Families Shows Their Widespread Existence and Extreme Heterogeneity in Plant Genomes[W

    Science.gov (United States)

    Wenke, Torsten; Döbel, Thomas; Sörensen, Thomas Rosleff; Junghans, Holger; Weisshaar, Bernd; Schmidt, Thomas

    2011-01-01

    Short interspersed nuclear elements (SINEs) are non-long terminal repeat retrotransposons that are highly abundant, heterogeneous, and mostly not annotated in eukaryotic genomes. We developed a tool designated SINE-Finder for the targeted discovery of tRNA-derived SINEs. We analyzed sequence data of 16 plant genomes, including 13 angiosperms and three gymnosperms and identified 17,829 full-length and truncated SINEs falling into 31 families showing the widespread occurrence of SINEs in higher plants. The investigation focused on potato (Solanum tuberosum), resulting in the detection of seven different SolS SINE families consisting of 1489 full-length and 870 5′ truncated copies. Consensus sequences of full-length members range in size from 106 to 244 bp depending on the SINE family. SolS SINEs populated related species and evolved separately, which led to some distinct subfamilies. Solanaceae SINEs are dispersed along chromosomes and distributed without clustering but with preferred integration into short A-rich motifs. They emerged more than 23 million years ago and were species specifically amplified during the radiation of potato, tomato (Solanum lycopersicum), and tobacco (Nicotiana tabacum). We show that tobacco TS retrotransposons are composite SINEs consisting of the 3′ end of a long interspersed nuclear element integrated downstream of a nonhomologous SINE family followed by successfully colonization of the genome. We propose an evolutionary scenario for the formation of TS as a spontaneous event, which could be typical for the emergence of SINE families. PMID:21908723

  10. Short Communication: In vitro response of papaya (Carica papaya to plant growth regulators

    Directory of Open Access Journals (Sweden)

    JAIME A. TEIXEIRA DA SILVA

    2016-01-01

    Full Text Available Abstract. Teixeira da Silva JA. 2016. In vitro response of papaya (Carica papaya to multiple plant growth regulators. Nusantara Bioscience 8: 77-82. The use of plant growth regulators (PGRs in papaya (Carica papaya L. tissue culture is essential for tissue and organ culture in vitro. In this study, in a bid to expand the information available on the response to PGRs, a wide range of PGRs, roughly divided into four groups (auxins, cytokinins, alternative PGRs, growth inhibitors and retardants was tested. Among them, the auxins 2,4-D, dicamba and picloram formed most callus (hard and soft. Callus inductions by chitosan and coconut water are novel results for papaya. Shoots only formed in response to BA and TDZ, but TDZ-induced shoots were fasciated and/or hyperhydric. These results provide novel perspectives for papaya researchers who may have recalcitrant genotypes or tissues that are unresponsive in vitro.

  11. Short-Term Forecasting of Inertial Response from a Wind Power Plant: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard; Gevorgian, Vahan; Hoke, Andy

    2016-09-01

    The total inertia stored in all rotating masses (synchronous generators, induction motors, etc.) connected to a power system grid is an essential force that keeps the system stable after disturbances. Power systems have been experiencing reduced inertia during the past few decades [1]. This trend will continue as the level of renewable generation (e.g., wind and solar) increases. Wind power plants (WPPs) and other renewable power plants with power electronic interfaces are capable of delivering frequency response (both droop and/or inertial response) by a control action; thus, the reduction in available online inertia can be compensated by designing the plant control to include frequency response. The source of energy to be delivered as inertial response is determined by the type of generation (wind, photovoltaic, concentrating solar power, etc.) and the control strategy chosen. The importance of providing ancillary services to ensure frequency control within a power system is evidenced from many recent publications with different perspectives (manufacturer, system operator, regulator, etc.) [2]-[6]. This paper is intended to provide operators with a method for the real-time assessment of the available inertia of a WPP. This is critical to managing power system stability and the reserve margin. In many states, modern WPPs are required to provide ancillary services (e.g., frequency regulation via governor response and inertial response) to the grid. This paper describes the method of estimating the available inertia and the profile of the forecasted response from a WPP.

  12. Post-transcriptional gene silencing across kingdoms.

    Science.gov (United States)

    Cogoni, C; Macino, G

    2000-12-01

    Post-transcriptional gene silencing (PTGS) as a consequence of the introduction of either transgenes or double-stranded RNA molecules has been found to occur in a number of species. In the past year, studies in different systems have greatly enhanced our understanding of the molecular mechanisms of these phenomena. The ubiquitous presence of PTGS in both the plant and animal kingdoms and the finding of common genetic mechanisms suggest that PTGS is a universal gene-regulation system fundamental in biological processes such as protection against viruses and transposons.

  13. The Enamovirus P0 protein is a silencing suppressor which inhibits local and systemic RNA silencing through AGO1 degradation

    Energy Technology Data Exchange (ETDEWEB)

    Fusaro, Adriana F. [University of Sydney, NSW 2006 (Australia); CSIRO Plant Industry, Canberra, P.O. Box 1600, ACT 2601 (Australia); Correa, Regis L. [CSIRO Plant Industry, Canberra, P.O. Box 1600, ACT 2601 (Australia); Depto. de Virologia, IMPPG, UFRJ, 21941-902 (Brazil); Nakasugi, Kenlee; Jackson, Craig [University of Sydney, NSW 2006 (Australia); Kawchuk, Lawrence [Research Centre, Agriculture and Agri-Food Canada, Lethbridge, AB T1J4B1 (Canada); Vaslin, Maite F.S. [Depto. de Virologia, IMPPG, UFRJ, 21941-902 (Brazil); Waterhouse, Peter M., E-mail: peter.waterhouse@sydney.edu.au [University of Sydney, NSW 2006 (Australia); CSIRO Plant Industry, Canberra, P.O. Box 1600, ACT 2601 (Australia)

    2012-05-10

    The P0 protein of poleroviruses and P1 protein of sobemoviruses suppress the plant's RNA silencing machinery. Here we identified a silencing suppressor protein (SSP), P0{sup PE}, in the Enamovirus Pea enation mosaic virus-1 (PEMV-1) and showed that it and the P0s of poleroviruses Potato leaf roll virus and Cereal yellow dwarf virus have strong local and systemic SSP activity, while the P1 of Sobemovirus Southern bean mosaic virus supresses systemic silencing. The nuclear localized P0{sup PE} has no discernable sequence conservation with known SSPs, but proved to be a strong suppressor of local silencing and a moderate suppressor of systemic silencing. Like the P0s from poleroviruses, P0{sup PE} destabilizes AGO1 and this action is mediated by an F-box-like domain. Therefore, despite the lack of any sequence similarity, the poleroviral and enamoviral SSPs have a conserved mode of action upon the RNA silencing machinery.

  14. Long and short term effects of plasma treatment on meristematic plant cells

    Science.gov (United States)

    Puač, N.; Živković, S.; Selaković, N.; Milutinović, M.; Boljević, J.; Malović, G.; Petrović, Z. Lj.

    2014-05-01

    In this paper, we will present results of plasma treatments of meristematic cells of Daucus carota. Plasma needle was used as an atmospheric pressure/gas composition source of non-equilibrium plasma in all treatments. Activity of antioxidant enzymes superoxide dismutase and catalase was measured immediately after plasma treatment and after two weeks following the treatment. Superoxide dismutase activity was increased in samples immediately after the plasma treatment. On the other hand, catalase activity was much higher in treated samples when measured two weeks after plasma treatment. These results show that there is a direct proof of the triggering of signal transduction in the cells by two reactive oxygen species H2O2 and O2-, causing enzyme activity and short and long term effects even during the growth of calli, where the information is passed to newborn cells over the period of two weeks.

  15. Judicial review of administrative silence

    Directory of Open Access Journals (Sweden)

    Radošević Ratko S.

    2015-01-01

    Full Text Available Administrative silence is a situation in which the competent authority, within the statutory deadline, has not issued an administrative act at the request of the party. In the case of administrative silence, given the fact that the citizens are unable to protect their rights and legal interests without an administrative act, they are provided with legal protection. In this case, the same legal relationship is created, directly on the basis of the statute, as in the situation in which the party's request is rejected. This means that the party may, under the conditions prescribed by the statute, initiate the procedure of judicial review of administrative silence. In the paper, the author explains the conditions under which the judicial review of administrative silence can be initiated and the role of the court in this judicial procedure.

  16. Le silence des agneaux

    Directory of Open Access Journals (Sweden)

    BERNARD ROY

    2012-01-01

    Full Text Available Ce texte est avant tout une réflexion sur la notion d'obéissance, initiée à partir de deux évènements impliquant étroitement des membres de la profession infirmière. L'auteur se réjouit de la prise de parole et de l'implication directe d'infirmières dans le contexte du printemps érable. Il estime que la posture de ces infirmières s'inscrit dans ce que l'éthicien Guy Durand, appelle une obéissance autonome qui peut, du coup, mener à la désobéissance civile, à l'objection de conscience. En prenant exemple sur le silence des infirmières dans le contexte de la fermeture de postes d'infirmières en Minganie, l'auteur estime que cette posture est marginale chez les infirmières qui, majoritairement, adoptent une position de soumission et d'obéissance hétéronome.

  17. Towards new understandings of silence

    OpenAIRE

    Cronin, James G. R.

    2009-01-01

    Eye & Mind research seminar, History of Art ‘Fruit of Silence’, a reflective case study by American writer and teacher Marilyn Nelson (2006), considers the role of silence/meditation, what she terms as ‘contemplative pedagogy’, as a learning tool in teaching a literature class to cadets being trained at West Point followed by cadet responses to silence during their military service in Iraq during the Second Gulf War (2003--). Through letters, two former West Point cadets, who subsequently ...

  18. Short-term microbial dynamics in a drinking water plant treating groundwater with occasional high microbial loads.

    Science.gov (United States)

    Besmer, Michael D; Hammes, Frederik

    2016-12-15

    Short-term fluctuations in bacterial concentrations in drinking water systems, occurring on time scales of hours-to-weeks, are essentially unexplored due to a lack of microbial monitoring tools that allow high frequency measurements. Here, we applied fully automated online flow cytometry to measure the total cell concentrations (TCC) in both raw water (karstic groundwater) and treated water (flocculation - ultrafiltration (UF) - ozonation - granular active carbon (GAC) filtration) during a period of 70 days at high temporal resolution (n > 4000 for both water types). We detected and characterized in considerable detail aperiodic fluctuations in the raw water following regional precipitation, with TCC increasing up to 50-fold from a dry weather baseline of approximately 120 cells μl(-1) to an event peak of > 5000 cells μl(-1). Moreover, we observed the buffering of the treatment plant against these fluctuations, but in addition we recorded a completely unexpected periodic fluctuation of TCC in the treated water after GAC filtration. We concluded that the latter was the result of fluctuating water abstraction from the treatment plant reservoir by two connected water utilities, which resulted in variations in water throughput in the plant. This in turn influenced bacterial detachment and dilution in the GAC filter. This study provides strong evidence of multiple different microbial dynamics occurring in a drinking water treatment system. Given numerous possible sources of natural and operational fluctuations in raw water and drinking water treatment plants, such microbial fluctuations should be expected in many systems. The high-frequency monitoring approach presented herein can improve the understanding and eventual mitigation of such fluctuations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Silence, an Eye of Knowledge

    Directory of Open Access Journals (Sweden)

    Mehdi Aghamohammadi

    2017-04-01

    Full Text Available One of the conspicuous features of the twentieth-century West was silence. This idea could be supported by examining reflections of Ludwig Wittgenstein, Fritz Mauthner, John Cage, Samuel Beckett, Ihab Hassan, Franz Kafka, Wassily Kandinsky, Jean-Paul Sartre, Virginia Woolf, Wolfgang Iser, Jacques Derrida, and Pierre Macherey. To me, silence is not a mere theory, but rather a phenomenon from which we can get practical benefits. I believe silence is an eye, eye of knowledge. We can broaden our knowledge of the world through silence. To convey the idea that silence is an eye, I have concocted the word slence, where  has replaced the letter i and stands for the eye. This means knowledge can enable us to see, thereby acquiring knowledge of, what used to be invisible, and accordingly unknowable. In other words, through silence, we can achieve a certain type of literacy. I substantiate this claim by exploring the Horus myth, Ojo de Dios, John Cage’s 4' 33", the nature of Expressionist paintings, Hinduism, thoughts of Hermes Trismegistus and Ibn al-Arabi, and practices of Mohammad, the prophet of Islam.

  20. Protocol: using virus-induced gene silencing to study the arbuscular mycorrhizal symbiosis in Pisum sativum

    DEFF Research Database (Denmark)

    Grønlund, Mette; Olsen, Anne; Johansen, Elisabeth

    2010-01-01

    Virus-induced gene silencing (VIGS) is an alternative reverse genetics tool for silencing of genes in some plants, which are difficult to transform. The pea early-browning virus (PEBV) has been developed as a VIGS vector and used in pea for functional analysis of several genes. However, the avail......Virus-induced gene silencing (VIGS) is an alternative reverse genetics tool for silencing of genes in some plants, which are difficult to transform. The pea early-browning virus (PEBV) has been developed as a VIGS vector and used in pea for functional analysis of several genes. However......, the available PEBV-VIGS protocols are inadequate for studying genes involved in the symbiosis with arbuscular mycorrhizal fungi (AMF). Here we describe a PEBV-VIGS protocol suitable for reverse genetics studies in pea of genes involved in the symbiosis with AMF and show its effectiveness in silencing genes...... involved in the early and late stages of AMF symbiosis....

  1. The Effect of Short Rotation Desmodium distortum Planted Fallow on the Productivity of Ultisols in Centre Cameroon

    Directory of Open Access Journals (Sweden)

    Nguimgo, BAK.

    2004-01-01

    Full Text Available In order to investigate the effect of short rotation Desmodium distortum planted fallow on maize grain yield and soil properties, an experiment was conducted over four consecutive years (1995-1998 at two locations (Minkoameyos in the humid forest zone and Ntui in the forest-savannah transition zone in Centre Cameroon. The experimental design for each year was made of four replications and three treatments: i Natural Fallow used as control (NF, ii Desmodium Fallow (DF and iii Soybean (Glycine max Rotation (SR. Maize (Zea mays was used as plant test and was planted each year in the first cropping season (March-June followed by each treatment from July to February. The analysis of variance and mean separation (Tukey's HSD were used to evaluate the effects of treatments on maize yield and soil chemical properties at the end of the experiment. No treatment could produce relatively more than the first year of the experiment where maize yields were based on 7-8 year-old natural fallow in both sites. However, in Minkoameyos, there was a significant difference (p= 0.043 between the treatments in the fourth year. Desmodium plots out-yielded both natural fallow and soybean plots. In Ntui, there was a highly significant difference (p= 0.000 among treatments in the third and fourth years. Desmodium plots also outyielded both natural fallow and soybean plots; while natural fallow plots out-yielded soybean plots. The general trend of productivity was ranked as: DF> NF> SR. Apart from the available P that has shown a highly significant difference (p= 0.000 compared to the initial value and to other treatments, no other significant difference was noticed with other soil properties in both sites. However, the general trend is that most soil chemical properties tended to decrease excepted pH water and available phosphorus. The study has shown that, in forest-savannah–transition zone (Ntui, Desmodium distortum had highly significant effect on maize grain yield

  2. Energy plants increasingly important. Scientific results and practical experiences on the production of biogas plants and short rotation coppices. Symposium; Energiepflanzen im Aufwind. Wissenschaftliche Ergebnisse und praktische Erfahrungen zur Produktion von Biogaspflanzen und Feldholz. Fachtagung

    Energy Technology Data Exchange (ETDEWEB)

    Heiermann, M.; Scholz, V.; Foltan, H. (comps.)

    2007-05-15

    The conference proceedings contain 15 contributions on energy plants: energy plant production in Germany - developments and research activities; potentials and constraints of cultivating energy crops; environmental aspects of production and utilization of energy plants; costs of energy crop supply; crops for the biogas production in the territory of Brandenburg; mixed cropping systems on sandy soils - alternative cropping strategies; impact of ensiling process on biogas production - recent research results; solid state anaerobic digestion of renewable biomass sources - state of research and development; energy crops as feedstock in a biogas plant; proffer and demand of wood fuel in the State of Brandenburg; regulatory framework of growing short rotation coppice; mechanization of SRC production; 20 years of short rotation coppice; willow production and marketing in Denmark; short rotation coppice production in Italy.

  3. Short-term effects of burn season on flowering phenology of savanna plants

    Science.gov (United States)

    Pavlovic, N.B.; Leicht-Young, S. A.; Grundel, R.

    2011-01-01

    We examined the effect of season of burn on flowering phenology of groundlayer species, in the year following burns, in a mesic-sand Midwestern oak savanna. Burn treatments were fall, early-season, growing-season, late-season, and 1 or 5 years after a prior early-season wildfire. For these treatments, we compared the number of flowering stems and of flowers for species overall, for the 20 most prolifically flowering species, as well as for species grouped by flowering phenoperiods, and by growth form. Growing-season burn had a significant negative effect on number of flowering stems and total number of flowers. This effect occurred when either the burn occurred during the flowering season or during the season prior to the flowering phenoperiod. Tradescantia ohiensis showed expedited flowering and Phlox pilosa showed delayed flowering in response to early-season burning. Flowering of early shrubs was reduced by the previous fall and early-spring fires, while flowering of mid-season blooming shrubs was reduced by the early- and growing-season burns. Vaccinium and Gaylussacia, early-flowering shrubs, produced fewer flowers 1 year after than 5 years after an early-season burn. Arabis lyrata showed reduced flowering from the early-season burn. We also found four instances where the early-spring burn effect on flowering was more severe than the fall burn effect, suggesting that many frequent early-season burns may be deleterious to flowering and reproduction of some species. Burns occurring too frequently in the same season could negatively affect future flowering and reproduction of these plant species.

  4. Technical advances in trigger-induced RNA interference gene silencing in the parasite Entamoeba histolytica.

    Science.gov (United States)

    Khalil, Mohamed I; Foda, Bardees M; Suresh, Susmitha; Singh, Upinder

    2016-03-01

    Entamoeba histolytica has a robust endogenous RNA interference (RNAi) pathway. There are abundant 27 nucleotide (nt) anti-sense small RNAs (AS sRNAs) that target genes for silencing and the genome encodes many genes involved in the RNAi pathway such as Argonaute proteins. Importantly, an E. histolytica gene with numerous AS sRNAs can function as a "trigger" to induce silencing of a gene that is fused to the trigger. Thus, the amebic RNAi pathway regulates gene expression relevant to amebic biology and has additionally been harnessed as a tool for genetic manipulation. In this study we have further improved the trigger-induced gene silencing method. We demonstrate that rather than using the full-length gene, a short portion of the coding region fused to a trigger is sufficient to induce silencing; the first 537 bp of the E. histolytica rhomboid gene (EhROM1) fused in-frame to the trigger was sufficient to silence EhROM1. We also demonstrated that the trigger method could silence two amebic genes concomitantly; fusion of the coding regions of EhROM1 and transcription factor, EhMyb, in-frame to a trigger gene resulted in both genes being silenced. Alternatively, two genes can be silenced sequentially: EhROM1-silenced parasites with no drug selection plasmid were transfected with trigger-EhMyb, resulting in parasites with both EhROM1 and EhMyb silenced. With all approaches tested, the trigger-mediated silencing was substantive and silencing was maintained despite loss of the G418 selectable marker. All gene silencing was associated with generation of AS sRNAs to the silenced gene. We tested the reversibility of the trigger system using inhibitors of histone modifications but found that the silencing was highly stable. This work represents a technical advance in the trigger gene silencing method in E. histolytica. Approaches that readily silence multiple genes add significantly to the genetic toolkit available to the ameba research community. Copyright © 2016

  5. Gene-Silencing-Induced Changes in Carbohydrate Conformation in Relation to Bioenergy Value and Carbohydrate Subfractions in Modeled Plant (Medicago sativa) with Down-Regulation of HB12 and TT8 Transcription Factors.

    Science.gov (United States)

    Li, Xinxin; Hannoufa, Abdelali; Zhang, Yonggen; Yu, Peiqiang

    2016-05-13

    Gene silencing with RNA interference (RNAi) technology may be capable of modifying internal structure at a molecular level. This structural modification could affect biofunctions in terms of biodegradation, biochemical metabolism, and bioactive compound availability. The objectives of this study were to (1) Detect gene silencing-induced changes in carbohydrate molecular structure in an alfalfa forage (Medicago sativa spp. sativa: alfalfa) with down-regulation of genes that encode transcription factors TT8 and HB12; (2) Determine gene silencing-induced changes in nutrient bioutilization and bioavailability in the alfalfa forage (Medicago sativa); and (3) Quantify the correlation between gene silencing-induced molecular structure changes and the nutrient bioutilization and bioavailability in animals of ruminants. The experimental treatments included: T1 = Non-transgenic and no-gene silenced alfalfa forage (code "NT"); T2 = HB12-RNAi forage with HB12 gene down regulation (code "HB12"); T3 = TT8-RNAi forage with TT8 gene down regulation (code "TT8"). The HB12 and TT8 gene silencing-induced molecular structure changes were determined by non-invasive and non-destructive advanced molecular spectroscopy in a middle infrared radiation region that focused on structural, non-structural and total carbohydrate compounds. The nutrient bioutilization and bioavailability of the modified forage were determined using NRC-2001 system in terms of total digestive nutrient (TDN), truly digestible fiber (tdNDF), non-fiber carbohydrate (tdNDF), fatty acid (tdFA), crude protein (tdCP) and bioenergy profiles (digestible energy, metabolizable energy, net energy) for ruminants. The carbohydrate subfractions were evaluated using the updated CNCPS 6.0 system. The results showed that gene silencing significantly affected tdNFC (42.3 (NT) vs. 38.7 (HB12) vs. 37.4% Dry Matter (TT8); p = 0.016) and tdCP (20.8 (NT) vs. 19.4 (HB12) vs. 22.3% DM (TT8); p = 0.009). The gene-silencing also affected

  6. Development of a system for real-time measurements of metabolite transport in plants using short-lived positron-emitting radiotracers

    Science.gov (United States)

    Kiser, Matthew R.

    Over the past 200 years, the Earth's atmospheric carbon dioxide (CO 2) concentration has increased by more than 35%, and climate experts predict that CO2 levels may double by the end of this century. Understanding the mechanisms of resource management in plants is fundamental for predicting how plants will respond to the increase in atmospheric CO 2. Plant productivity sustains life on Earth and is a principal component of the planet's system that regulates atmospheric CO2 concentration. As such, one of the central goals of plant science is to understand the regulatory mechanisms of plant growth in a changing environment. Short-lived positron-emitting radiotracer techniques provide time-dependent data that are critical for developing models of metabolite transport and resource distribution in plants and their microenvironments. To better understand the effects of environmental changes on resource transport and allocation in plants, we have developed a system for real-time measurements of rnetabolite transport in plants using short-lived positron-emitting radio-tracers. This thesis project includes the design, construction, and demonstration of the capabilities of this system for performing real-time measurements of metabolite transport in plants. The short-lived radiotracer system described in this dissertation takes advantage of the combined capabilities and close proximity of two research facilities at. Duke University: the Triangle Universities Nuclear Laboratory (TUNL) and the Duke University Phytotron, which are separated by approximately 100 meters. The short-lived positron-emitting radioisotopes are generated using the 10-MV tandem Van de Graaff accelerator located in the main TUNL building, which provides the capability of producing short-lived positron-emitting isotopes such as carbon-11 (11C: 20 minute half-life), nitrogen-13 (13N; 10 minute half-life), fluorine-18 (18F; 110 minute half-life), and oxygen-15 (15O; 2 minute half-life). The radioisotopes may

  7. S-LOCUS EARLY FLOWERING 3 is exclusively present in the genomes of short-styled buckwheat plants that exhibit heteromorphic self-incompatibility.

    Science.gov (United States)

    Yasui, Yasuo; Mori, Masashi; Aii, Jotaro; Abe, Tomoko; Matsumoto, Daiki; Sato, Shingo; Hayashi, Yoriko; Ohnishi, Ohmi; Ota, Tatsuya

    2012-01-01

    The different forms of flowers in a species have attracted the attention of many evolutionary biologists, including Charles Darwin. In Fagopyrum esculentum (common buckwheat), the occurrence of dimorphic flowers, namely short-styled and long-styled flowers, is associated with a type of self-incompatibility (SI) called heteromorphic SI. The floral morphology and intra-morph incompatibility are both determined by a single genetic locus named the S-locus. Plants with short-styled flowers are heterozygous (S/s) and plants with long-styled flowers are homozygous recessive (s/s) at the S-locus. Despite recent progress in our understanding of the molecular basis of flower development and plant SI systems, the molecular mechanisms underlying heteromorphic SI remain unresolved. By examining differentially expressed genes from the styles of the two floral morphs, we identified a gene that is expressed only in short-styled plants. The novel gene identified was completely linked to the S-locus in a linkage analysis of 1,373 plants and had homology to EARLY FLOWERING 3. We named this gene S-LOCUS EARLY FLOWERING 3 (S-ELF3). In an ion-beam-induced mutant that harbored a deletion in the genomic region spanning S-ELF3, a phenotype shift from short-styled flowers to long-styled flowers was observed. Furthermore, S-ELF3 was present in the genome of short-styled plants and absent from that of long-styled plants both in world-wide landraces of buckwheat and in two distantly related Fagopyrum species that exhibit heteromorphic SI. Moreover, independent disruptions of S-ELF3 were detected in a recently emerged self-compatible Fagopyrum species and a self-compatible line of buckwheat. The nonessential role of S-ELF3 in the survival of individuals and the prolonged evolutionary presence only in the genomes of short-styled plants exhibiting heteromorphic SI suggests that S-ELF3 is a suitable candidate gene for the control of the short-styled phenotype of buckwheat plants.

  8. Transcriptional Silencing of Retroviral Vectors

    DEFF Research Database (Denmark)

    Lund, Anders Henrik; Duch, M.; Pedersen, F.S.

    1996-01-01

    . Extinction of long-term vector expression has been observed after implantation of transduced hematopoietic cells as well as fibroblasts, myoblasts and hepatocytes. Here we review the influence of vector structure, integration site and cell type on transcriptional silencing. While down-regulation of proviral...... transcription is known from a number of cellular and animal models, major insight has been gained from studies in the germ line and embryonal cells of the mouse. Key elements for the transfer and expression of retroviral vectors, such as the viral transcriptional enhancer and the binding site for the t......RNA primer for reverse transcription may have a major influence on transcriptional silencing. Alterations of these elements of the vector backbone as well as the use of internal promoter elements from housekeeping genes may contribute to reduce transcriptional silencing. The use of cell culture and animal...

  9. Aucsia gene silencing causes parthenocarpic fruit development in tomato.

    Science.gov (United States)

    Molesini, Barbara; Pandolfini, Tiziana; Rotino, Giuseppe Leonardo; Dani, Valeria; Spena, Angelo

    2009-01-01

    In angiosperms, auxin phytohormones play a crucial regulatory role in fruit initiation. The expression of auxin biosynthesis genes in ovules and placenta results in uncoupling of tomato (Solanum lycopersicum) fruit development from fertilization with production of parthenocarpic fruits. We have identified two newly described genes, named Aucsia genes, which are differentially expressed in auxin-synthesis (DefH9-iaaM) parthenocarpic tomato flower buds. The two tomato Aucsia genes encode 53-amino-acid-long peptides. We show, by RNA interference-mediated gene suppression, that Aucsia genes are involved in both reproductive and vegetative plant development. Aucsia-silenced tomato plants exhibited auxin-related phenotypes such as parthenocarpic fruit development, leaf fusions, and reflexed leaves. Auxin-induced rhizogenesis in cotyledon explants and polar auxin transport in roots were reduced in Aucsia-silenced plants compared with wild-type plants. In addition, Aucsia-silenced plants showed an increased sensitivity to 1-naphthylphthalamic acid, an inhibitor of polar auxin transport. We further prove that total indole-3-acetic acid content was increased in preanthesis Aucsia-silenced flower buds. Thus, the data presented demonstrate that Aucsia genes encode a novel family of plant peptides that control fruit initiation and affect other auxin-related biological processes in tomato. Aucsia homologous genes are present in both chlorophytes and streptophytes, and the encoded peptides are distinguished by a 16-amino-acid-long (PYSGXSTLALVARXSA) AUCSIA motif, a lysine-rich carboxyl-terminal region, and a conserved tyrosine-based endocytic sorting motif.

  10. Life cycle assessment of biomass chains: Wood pellet from short rotation coppice using data measured on a real plant

    Energy Technology Data Exchange (ETDEWEB)

    Fantozzi, Francesco; Buratti, Cinzia [University of Perugia - Biomass Research Centre, Via Duranti - 06125 Perugia (Italy)

    2010-12-15

    This paper presents a LCA study about household heat from Short Rotation Coppice wood pellets combustion. The overall process, from field growth to ash disposal, was considered; environmental analysis was carried out using a LCA software programme (Simapro 7.0) and adopting the EcoIndicator 99 model for the evaluation of the global burden; analysis with EPS 2000 and EDIP methodologies were also carried out, in order to compare the different approaches. For the pellet production process, mass and energy flows were measured on an existing Italian plant, while other data were obtained from the Literature; a comparison between results obtained using only data from Literature and using data from the existing plant was made, showing for the pelleting phase a value of about 23% lower if measured data are used. The LCA study showed that agricultural operations account for most of the environmental impact if evaluated both with EcoIndicator 99 and EPS 2000; EDIP gave results that were not very reliable for this chain, due to the high weight given to the infra-structures and machinery construction. The comparison between data obtained considering and not considering the infra-structures contribution in the LCA analysis with EcoIndicator 99 showed a modest contribution of infra-structures on the final score (about 2%). The overall impact evaluated with EcoIndicator 99 is considerably less than the one caused by natural gas heating. The Energy Return Ratio was finally calculated; a value of 3.25 was found, good if compared to the one for the methane combustion, equal to 6. (author)

  11. Strain Specific Factors Control Effector Gene Silencing in Phytophthora sojae.

    Directory of Open Access Journals (Sweden)

    Sirjana Devi Shrestha

    Full Text Available The Phytophthora sojae avirulence gene Avr3a encodes an effector that is capable of triggering immunity on soybean plants carrying the resistance gene Rps3a. P. sojae strains that express Avr3a are avirulent to Rps3a plants, while strains that do not are virulent. To study the inheritance of Avr3a expression and virulence towards Rps3a, genetic crosses and self-fertilizations were performed. A cross between P. sojae strains ACR10 X P7076 causes transgenerational gene silencing of Avr3a allele, and this effect is meiotically stable up to the F5 generation. However, test-crosses of F1 progeny (ACR10 X P7076 with strain P6497 result in the release of silencing of Avr3a. Expression of Avr3a in the progeny is variable and correlates with the phenotypic penetrance of the avirulence trait. The F1 progeny from a direct cross of P6497 X ACR10 segregate for inheritance for Avr3a expression, a result that could not be explained by parental imprinting or heterozygosity. Analysis of small RNA arising from the Avr3a gene sequence in the parental strains and hybrid progeny suggests that the presence of small RNA is necessary but not sufficient for gene silencing. Overall, we conclude that inheritance of the Avr3a gene silenced phenotype relies on factors that are variable among P. sojae strains.

  12. Strain Specific Factors Control Effector Gene Silencing in Phytophthora sojae.

    Science.gov (United States)

    Shrestha, Sirjana Devi; Chapman, Patrick; Zhang, Yun; Gijzen, Mark

    2016-01-01

    The Phytophthora sojae avirulence gene Avr3a encodes an effector that is capable of triggering immunity on soybean plants carrying the resistance gene Rps3a. P. sojae strains that express Avr3a are avirulent to Rps3a plants, while strains that do not are virulent. To study the inheritance of Avr3a expression and virulence towards Rps3a, genetic crosses and self-fertilizations were performed. A cross between P. sojae strains ACR10 X P7076 causes transgenerational gene silencing of Avr3a allele, and this effect is meiotically stable up to the F5 generation. However, test-crosses of F1 progeny (ACR10 X P7076) with strain P6497 result in the release of silencing of Avr3a. Expression of Avr3a in the progeny is variable and correlates with the phenotypic penetrance of the avirulence trait. The F1 progeny from a direct cross of P6497 X ACR10 segregate for inheritance for Avr3a expression, a result that could not be explained by parental imprinting or heterozygosity. Analysis of small RNA arising from the Avr3a gene sequence in the parental strains and hybrid progeny suggests that the presence of small RNA is necessary but not sufficient for gene silencing. Overall, we conclude that inheritance of the Avr3a gene silenced phenotype relies on factors that are variable among P. sojae strains.

  13. Two amino acids near the N-terminus of Cucumber mosaic virus 2b play critical roles in the suppression of RNA silencing and viral infectivity.

    Science.gov (United States)

    Dong, Kai; Wang, Ying; Zhang, Zhen; Chai, Long-Xiang; Tong, Xin; Xu, Jin; Li, Dawei; Wang, Xian-Bing

    2016-02-01

    Cucumber mosaic virus (CMV) 2b suppresses RNA silencing primarily through the binding of double-stranded RNA (dsRNA) of varying sizes. However, the biologically active form of 2b remains elusive. Here, we demonstrate that the single and double alanine substitution mutants in the N-terminal 15th leucine and 18th methionine of CMV 2b exhibit drastically attenuated virulence in wild-type plants, but are efficiently rescued in mutant plants defective in RNA-dependent RNA polymerase 6 (RDR6) and Dicer-like 4 (DCL4). Moreover, the transgenic plants of 2b, but not 2blm (L15A/M18A), rescue the high infectivity of CMV-Δ2b through the suppression of antiviral silencing. L15A, M18A or both weaken 2b suppressor activity on local and systemic transgene silencing. In contrast with the high affinity of 2b to short and long dsRNAs, 2blm is significantly compromised in 21-bp duplex small interfering RNA (siRNA) binding ability, but maintains a strong affinity for long dsRNAs. In cross-linking assays, 2b can form dimers, tetramers and oligomers after treatment with glutaraldehyde, whereas 2blm only forms dimers, rather than tetramers and oligomers, in vitro. Together, these findings suggest that L15 and M18 of CMV 2b are required for high affinity to ds-siRNAs and oligomerization activity, which are essential for the suppression activity of 2b on antiviral silencing.

  14. Suppressor of RNA silencing encoded by Rice gall dwarf virus genome segment 11

    Institute of Scientific and Technical Information of China (English)

    LIU FuXiu; ZHAO Qin; RUAN XiaoLei; HE YunWei; LI HuaPing

    2008-01-01

    Rice gall dwarf virus (RGDV) is an important rice pathogen in China and Southeast Asia. However, little is known about the molecular mechanisms of RGDV interactions with plant cells. Here, we have identi-fied an RGDV protein, Pns11, which acts as a suppressor of RNA silencing in coinfiltration assays with the reporter, green fluorescent protein (GFP) in transgenic Nicotiana bentharniana line 16c carrying GFP. Pns11 suppressed local and systemic silencing induced by sense RNA. The spread of mobile FINA si-lencing signals was blocked or inactivated by Pns11. Expression of Pns11 also enhanced Potato virus X pathogenicity in N. benthamiana. This suppressor could reduce, but not eliminate, siRNA in the local and systemic RNA silencing suppression assays, suggesting that Pns11 functions by interfering with initial stages of RNA silencing.

  15. The silence of the archive

    CERN Document Server

    Thomas, David; Thomas, David

    2017-01-01

    This new book will provide a ground breaking discussion of a major but little considered issue - the silence of the archive: why archives, sometimes seen as the repositories of truth, often fail to satisfy users because they do not contain information which they expect to find.

  16. Silence in the creative process

    Directory of Open Access Journals (Sweden)

    Francesco Wilhelm

    2015-01-01

    Full Text Available A research about silence as the moment where creative thinking takes place, as an art object and as a way of interpreting artworks, is the main issue of the graduation thesis named Il silenzio nel processo creativo (2014. Here is proposed an offprint, which summarizes its fundamental steps.

  17. Venturis as silencers -- Case history

    Energy Technology Data Exchange (ETDEWEB)

    Kelsall, T.; Gerritsen, T. (Hatch Associates Ltd., Mississauga, Ontario (Canada)); Landon, T.S. (Wheeling-Pittsburgh Steel Corp., Steubenville, OH (United States). Steubenville Plant)

    1994-09-01

    Wheeling-Pittsburgh Steel replaced a BOF scrubber stack and started to receive complaints about a tonal noise. The replacement stack was identical to the original, except that the original stack contained splitters and a venturi used to measure flow. Hatch Associates investigated and determined that removal of the venturi had caused an increase in sound level. After review of silencing options, it was decided to install a venturi similar to the original because of its inherent advantages over conventional silences. When the venturi was replaced, the sound level of the tone measured in the community dropped on the order of 10 to 15 decibels. Investigation of the physical mechanism causing this reduction has led to development of a new type of fan silencer. Based on the venturi shape, Modal Silencers (patent pending) can be designed to substantially reduce sound levels from stacks. They have low pressure drop and the absence of internal baffles or chambers means that they do not clog in dirty or wet environments.

  18. Silence or the Sound of Limpid Water: Disability, Power, and the Educationalisation of Silence

    Science.gov (United States)

    Verstraete, Pieter

    2017-01-01

    In this article the history of silence is looked at from an educational perspective. By closely examining the way three nineteenth-century authors--who all based their educational theories on concrete experiences with persons with disabilities--have related themselves to silence, it will be argued that silence has been educationalised. Silence has…

  19. Horreur et silence : le personnage de Pierre Cange dans l’œuvre narrative de Vercors

    Directory of Open Access Journals (Sweden)

    Elisabetta Sibilio

    2015-11-01

    Full Text Available Vercors, who achieved fame thanks to his first novel, Le silence de la mer, published undercover in 1942, makes silence one of the main themes in his work. Silence, which is the paradoxical expression of what Vercors calls “la qualité d’homme”, appears in his work according to two major categories: on the one hand the proud and resilient silence of the protagonist of Silence de la mer or of Arnaud, the main character of the short story Le démenti, who loses his life for having maintained an obstinate silence in the hands of his torturers; on the other hand, the guilty and desperate shameful silence of those who had lost their own humanity when faced with the horror of the camps or had hoped to save their lives by col-laborating with the enemy. This paper will examine three of Vercors’ texts, Les armes de la nuit (1946, La puissance du jour (1951 and Le tigre d’Anvers (1986, which have Pierre Cange as protagonist, a member of the Resistance, deported, who through his own experience is faced with the funda-mental theme of silence.

  20. Transcription-dependent silencing of inducible convergent transgenes in transgenic mice

    Directory of Open Access Journals (Sweden)

    Calero-Nieto Fernando J

    2010-01-01

    Full Text Available Abstract Background Silencing of transgenes in mice is a common phenomenon typically associated with short multi-copy transgenes. We have investigated the regulation of the highly inducible human granulocyte-macrophage colony-stimulating-factor gene (Csf2 in transgenic mice. Results In the absence of any previous history of transcriptional activation, this transgene was expressed in T lineage cells at the correct inducible level in all lines of mice tested. In contrast, the transgene was silenced in a specific subset of lines in T cells that had encountered a previous episode of activation. Transgene silencing appeared to be both transcription-dependent and mediated by epigenetic mechanisms. Silencing was accompanied by loss of DNase I hypersensitive sites and inability to recruit RNA polymerase II upon stimulation. This pattern of silencing was reflected by increased methylation and decreased acetylation of histone H3 K9 in the transgene. We found that silenced lines were specifically associated with a single pair of tail-to-tail inverted repeated copies of the transgene embedded within a multi-copy array. Conclusions Our study suggests that epigenetic transgene silencing can result from convergent transcription of inverted repeats which can lead to silencing of an entire multi-copy transgene array. This mechanism may account for a significant proportion of the reported cases of transgene inactivation in mice.

  1. Tobacco mosaic virus movement protein enhances the spread of RNA silencing.

    Directory of Open Access Journals (Sweden)

    Hannes Vogler

    2008-04-01

    Full Text Available Eukaryotic cells restrain the activity of foreign genetic elements, including viruses, through RNA silencing. Although viruses encode suppressors of silencing to support their propagation, viruses may also exploit silencing to regulate host gene expression or to control the level of their accumulation and thus to reduce damage to the host. RNA silencing in plants propagates from cell to cell and systemically via a sequence-specific signal. Since the signal spreads between cells through plasmodesmata like the viruses themselves, virus-encoded plasmodesmata-manipulating movement proteins (MP may have a central role in compatible virus:host interactions by suppressing or enhancing the spread of the signal. Here, we have addressed the propagation of GFP silencing in the presence and absence of MP and MP mutants. We show that the protein enhances the spread of silencing. Small RNA analysis indicates that MP does not enhance the silencing pathway but rather enhances the transport of the signal through plasmodesmata. The ability to enhance the spread of silencing is maintained by certain MP mutants that can move between cells but which have defects in subcellular localization and do not support the spread of viral RNA. Using MP expressing and non-expressing virus mutants with a disabled silencing suppressing function, we provide evidence indicating that viral MP contributes to anti-viral silencing during infection. Our results suggest a role of MP in controlling virus propagation in the infected host by supporting the spread of silencing signal. This activity of MP involves only a subset of its properties implicated in the spread of viral RNA.

  2. Reducing the establishment costs of short rotation willow coppice (SRC) - A trial of a novel layflat planting system at an upland site in mid-Wales

    Energy Technology Data Exchange (ETDEWEB)

    Lowthe-Thomas, S.C.; Slater, F.M. [Cardiff University, Llysdinam Field Centre, Newbridge-on-Wye, Llandrindod Wells, Powys, LD1 6NB (United Kingdom); Randerson, P.F. [School of Biosciences, BIOSI 2, Cardiff University, Cardiff, CF10 3US (United Kingdom)

    2010-05-15

    Two mechanical planting systems, the traditional Turton Step planter and a prototype layflat planter, were compared for the planting and establishment of short rotation willow coppice (SRC) at an upland site in Mid-Wales. Planted during March 2000, both plots were monitored for three seasons and after this establishment phase monitoring continued for the layflat planted plot until year three of a second rotation. Establishment parameters of stem density, survival rates and estimated biomass yields of a range of willow varieties during the first three years growth were greater for the layflat planted willows than step planted. At the first harvest (4 growing seasons), layflat planted willows achieved mean yields of 6.22 odt ha{sup -1} yr{sup -1}, three years into the second rotation estimated yields ranged from 1.99 odt ha{sup -1} yr{sup -1} to 12.34 odt ha{sup -1} yr{sup -1} (mean of 8.14 odt ha{sup -1} yr{sup -1}). Since layflat planting has been shown to reduce planting costs by up to 48%, and yields achieved were equivalent to traditionally planted SRC, it is clear that this method of planting could provide an economic alternative to the traditional step planter. It is recommended that further trials take place using new varieties available, particularly to investigate stem density/thinning effects and harvesting time, and also to test recent modifications to the planter which allow adjustable planting depth for planting under drier soil conditions. (author)

  3. Silence as a sequel of the Peruvian internal war

    OpenAIRE

    Javier Mª. Iguíñiz Echeverría

    2006-01-01

    The internal war that took place in Peru for two decades brought silence as one of its consequences. In this article we try to classify silence or aspects of silence. This classification, based on the experiences described in the Report of the Truth and Reconciliation Commission (CVR, 2003), distinguishes an instrumental silence or silence for; a silence caused by the terrible events that took place or silence from; a silence resulting from the absence of important relations for an intimate c...

  4. A petunia ocs element binding factor, PhOBF1, plays an important role in antiviral RNA silencing

    Science.gov (United States)

    Virus-induced gene silencing (VIGS) is a common strategy of reverse genetics for characterizing function of genes in plant. The detailed mechanism governing RNA silencing efficiency triggered by virus is largely unclear. Here, we revealed that a petunia (Petunia hybrida) ocs element binding factor, ...

  5. Varying the nucleic acid composition of siRNA molecules dramatically varies the duration and degree of gene silencing.

    Science.gov (United States)

    Lamberton, Janelle S; Christian, Allen T

    2003-06-01

    The utility of short interfering RNA (siRNA) as a means of gene silencing depends on several factors. These include the degree to which a gene can be silenced, the length of time for which the gene remains silenced, the degree of recovery of gene function, and the effects of the silencing process on general cell functions. We hypothesized that changing the nucleic acid composition of the siRNA constructs used for silencing would affect these parameters. With siRNA gene silencing of the glucose-6-phosphate dehydrogenase gene as a baseline, we found that siDNA molecules have an effect that is similar in duration but lesser in degree, whereas hybrid DNA:RNA molecules have an effect that is enormously greater in both duration and degree.

  6. Modification of a viral satellite DNA-based gene silencing vector and its application to leaf or flower color change in Petunia hybrida

    Institute of Scientific and Technical Information of China (English)

    TAO Xiaorong; QIAN Yajuan; ZHOU Xueping

    2006-01-01

    Virus-induced gene silencing offers a powerful reverse-genetic tool for the study of gene function in plants. We have previously reported effective gene silencing of plant genes using a viral satellite DNA associated with Tomato yellow leaf curl China virus (TYLCCNV). In this study, we further modified the viral satellite DNA-based vector. The modified vector can induce sulfu (Su) gene silencing as effective as the original vector in Nicotiana benthamiana plants, but the new system simplifies procedures for construction of vector derivative. Furthermore, a fragment of petunia Su or chalcone synthase (CHS) endogenous gene was inserted into the modified vector. When petunia plants were agro- inoculated with the modified vector carrying a Su or CHS gene, the Su silenced plants started to appear yellowing in veins of systemically infected upper leaves two weeks after agroinoculation, while the CHS silenced plants started to show flower color change one month after agroinoculation and later single-color flowers became mosaic.

  7. [Silence potentiates chemosensitivity of K562 cells to SAHA].

    Science.gov (United States)

    Wang, Hou-Cai; Chen, Jing; An, Na; Yu, Teng-Teng; Li, Shou-Yun; Liu, Shuang; Wei, Hui; Rao, Qing; Wang, Min; Wang, Jian-Xiang

    2014-08-01

    Ribosomal protein S27a (RPS27a) can perform extra-ribosomal functions besides imparting a role in ribosome biogenesis and post-translational modifications of proteins. The RPS27a gene has been reported to be over-expressed in breast fibroadenomas, colorectal and renal cancers, advanced-phase chronic myeloid leukemia (CML) and acute leukemia (AL) patients. This study was purposed to explore the function of RPS27a in CML-erythroleukemia cell line K562 cells. RPS27a was silenced by short hairpin RNA (shRNA) in K562 cells. Furthermore, the proliferation changes of K562 cells was detected by MTT method after silencing the RPS27a with suberoylanilide hydroxamic acid (SAHA), then the IC50 of K562-sh1/sh2 and K562-scr cells to SAHA was measured. The results indicated that compared with K562-scr cells, the IC50 of K562-sh1/sh2 to SAHA at 24 h and 48 h decreased (P silence significantly increased the percentage of apoptotic K562-sh1/sh2 cells after incubation with 1 µmol/L, 2 µmol/L and 5 µmol/L SAHA for 24 h and 48 h as compared with that of K562-scr cells (P silence can potentiate sensitivity of K562 cells to SAHA.

  8. Silencing by small RNAs is linked to endosomal trafficking.

    Science.gov (United States)

    Lee, Young Sik; Pressman, Sigal; Andress, Arlise P; Kim, Kevin; White, Jamie L; Cassidy, Justin J; Li, Xin; Lubell, Kim; Lim, Do Hwan; Cho, Ik Sang; Nakahara, Kenji; Preall, Jonathan B; Bellare, Priya; Sontheimer, Erik J; Carthew, Richard W

    2009-09-01

    Small RNAs direct RNA-induced silencing complexes (RISCs) to regulate stability and translation of mRNAs. RISCs associated with target mRNAs often accumulate in discrete cytoplasmic foci known as GW-bodies. However, RISC proteins can associate with membrane compartments such as the Golgi and endoplasmic reticulum. Here, we show that GW-bodies are associated with late endosomes (multivesicular bodies, MVBs). Blocking the maturation of MVBs into lysosomes by loss of the tethering factor HPS4 (ref. 5) enhances short interfering RNA (siRNA)- and micro RNA (miRNA)-mediated silencing in Drosophila melanogaster and humans. It also triggers over-accumulation of GW-bodies. Blocking MVB formation by ESCRT (endosomal sorting complex required for transport) depletion results in impaired miRNA silencing and loss of GW-bodies. These results indicate that active RISCs are physically and functionally coupled to MVBs. We further show that MVBs promote the competence of RISCs in loading small RNAs. We suggest that the recycling of RISCs is promoted by MVBs, resulting in RISCs more effectively engaging with small RNA effectors and possibly target RNAs. It may provide a means to enhance the dynamics of RNA silencing in the cytoplasm.

  9. The VP3 factor from viruses of Birnaviridae family suppresses RNA silencing by binding both long and small RNA duplexes.

    Science.gov (United States)

    Valli, Adrian; Busnadiego, Idoia; Maliogka, Varvara; Ferrero, Diego; Castón, José R; Rodríguez, José Francisco; García, Juan Antonio

    2012-01-01

    RNA silencing is directly involved in antiviral defense in a wide variety of eukaryotic organisms, including plants, fungi, invertebrates, and presumably vertebrate animals. The study of RNA silencing-mediated antiviral defences in vertebrates is hampered by the overlap with other antiviral mechanisms; thus, heterologous systems are often used to study the interplay between RNA silencing and vertebrate-infecting viruses. In this report we show that the VP3 protein of the avian birnavirus Infectious bursal disease virus (IBDV) displays, in addition to its capacity to bind long double-stranded RNA, the ability to interact with double-stranded small RNA molecules. We also demonstrate that IBDV VP3 prevents the silencing mediated degradation of a reporter mRNA, and that this silencing suppression activity depends on its RNA binding ability. Furthermore, we find that the anti-silencing activity of IBDV VP3 is shared with the homologous proteins expressed by both insect- and fish-infecting birnaviruses. Finally, we show that IBDV VP3 can functionally replace the well-characterized HCPro silencing suppressor of Plum pox virus, a potyvirus that is unable to infect plants in the absence of an active silencing suppressor. Altogether, our results support the idea that VP3 protects the viral genome from host sentinels, including those of the RNA silencing machinery.

  10. The VP3 factor from viruses of Birnaviridae family suppresses RNA silencing by binding both long and small RNA duplexes.

    Directory of Open Access Journals (Sweden)

    Adrian Valli

    Full Text Available RNA silencing is directly involved in antiviral defense in a wide variety of eukaryotic organisms, including plants, fungi, invertebrates, and presumably vertebrate animals. The study of RNA silencing-mediated antiviral defences in vertebrates is hampered by the overlap with other antiviral mechanisms; thus, heterologous systems are often used to study the interplay between RNA silencing and vertebrate-infecting viruses. In this report we show that the VP3 protein of the avian birnavirus Infectious bursal disease virus (IBDV displays, in addition to its capacity to bind long double-stranded RNA, the ability to interact with double-stranded small RNA molecules. We also demonstrate that IBDV VP3 prevents the silencing mediated degradation of a reporter mRNA, and that this silencing suppression activity depends on its RNA binding ability. Furthermore, we find that the anti-silencing activity of IBDV VP3 is shared with the homologous proteins expressed by both insect- and fish-infecting birnaviruses. Finally, we show that IBDV VP3 can functionally replace the well-characterized HCPro silencing suppressor of Plum pox virus, a potyvirus that is unable to infect plants in the absence of an active silencing suppressor. Altogether, our results support the idea that VP3 protects the viral genome from host sentinels, including those of the RNA silencing machinery.

  11. Silencing of the ACC synthase gene ACACS2 causes delayed flowering in pineapple [Ananas comosus (L.) Merr.].

    Science.gov (United States)

    Trusov, Yuri; Botella, José Ramón

    2006-01-01

    Flowering is a crucial developmental stage in the plant life cycle. A number of different factors, from environmental to chemical, can trigger flowering. In pineapple, and other bromeliads, it has been proposed that flowering is triggered by a small burst of ethylene production in the meristem in response to environmental cues. A 1-amino-cyclopropane-1-carboxylate synthase (ACC synthase) gene has been cloned from pineapple (ACACS2), which is induced in the meristem under the same environmental conditions that induce flowering. Two transgenic pineapple lines have been produced containing co-suppression constructs designed to down-regulate the expression of the ACACS2 gene. Northern analysis revealed that the ACACS2 gene was silenced in a number of transgenic plants in both lines. Southern hybridization revealed clear differences in the methylation status of silenced versus non-silenced plants by the inability of a methylation-sensitive enzyme to digest within the ACACS2 DNA extracted from silenced plants, indicating that methylation is the cause of the observed co-suppression of the ACACS2 gene. Flowering characteristics of the transgenic plants were studied under field conditions in South East Queensland, Australia. Flowering dynamics studies revealed significant differences in flowering behaviour, with transgenic plants exhibiting silencing showing a marked delay in flowering when compared with non-silenced transgenic plants and control non-transformed plants. It is argued that the ACACS2 gene is one of the key contributors towards triggering 'natural flowering' in mature pineapples under commercial field conditions.

  12. Efficiency for Gene Silencing Induction in Nicotiana Species by a Viral Satellite DNA Vector

    Institute of Scientific and Technical Information of China (English)

    You-Ping Xu; Lu-Ping Zheng; Qiu-Fang Xu; Chang-Chun Wang; Xue-Ping Zhou; Zu-Jian Wu; Xin-Zhong Cai

    2007-01-01

    Virus-induced gene silencing (VIGS) is a useful technique for rapid plant gene function analysis.We recently reported a new VIGS vector modified from Tomato yellow leaf curl China virus (TYLCCNV) DNAβ (DNAm β).In this study we compared In detail DNAmβ-induced gene silencing in four Nicotiana species including N.benthamiana, N.glutinosa, N.tabacum and N.paniculata.We found that DNAmβ-induced gene silencing in the four species was distinct in developing dynamics, tissue specificity, efficiency, and constancy in the plant life span.It was most efficient in N.benthamiana, where development of VIGS was most rapid, without tissue specificity and nearly 100% efficient.DNAmβ-induced gene silencing in N.Glutinosa was also efficient despite being slightly less than in N.benthamiana.It initially occurred in veins, later was scattered to mesophyll, finally led to complete silencing in whole leaves.In both species, VIGS constantly expressed until the plants died.However, DNAmβ-mediated VIGS in the other two Nicotiana species, N.tabacum and N.paniculata, was significantly less efficient.It was strictly limited within the veins of the silenced leaves, and constantly occurred only over 3-4 weeks.The upper leaves that emerged later stopped showing the silencing phenotype, DNAm β-induced gene silencing in N.benthamiana and N.glutinosa was not significantly influenced by the growth stage when the plants were agro-inoculated,and was not sensitive to high growth temperature up to 32℃, Our results indicate that this system has great potential as a versatile VIGS system for routine functional analysis of genes in some Nicotiana species.

  13. Polycomb complexes and silencing mechanisms

    DEFF Research Database (Denmark)

    Lund, Anders H; van Lohuizen, Maarten

    2004-01-01

    Advances in the past couple of years have brought important new knowledge on the mechanisms by which Polycomb-group proteins regulate gene expression and on the consequences of their actions. The discovery of histone methylation imprints specific for Polycomb and Trithorax complexes has provided ...... mechanistic insight on how this ancient epigenetic memory system acts to repress and indicates that it may share mechanistic aspects with other silencing and genome-protective processes, such as RNA interference....

  14. Host-induced gene silencing of an essential chitin synthase gene confers durable resistance to Fusarium head blight and seedling blight in wheat.

    Science.gov (United States)

    Cheng, Wei; Song, Xiu-Shi; Li, He-Ping; Cao, Le-Hui; Sun, Ke; Qiu, Xiao-Li; Xu, Yu-Bin; Yang, Peng; Huang, Tao; Zhang, Jing-Bo; Qu, Bo; Liao, Yu-Cai

    2015-12-01

    Fusarium head blight (FHB) and Fusarium seedling blight (FSB) of wheat, caused by Fusarium pathogens, are devastating diseases worldwide. We report the expression of RNA interference (RNAi) sequences derived from an essential Fusarium graminearum (Fg) virulence gene, chitin synthase (Chs) 3b, as a method to enhance resistance of wheat plants to fungal pathogens. Deletion of Chs3b was lethal to Fg; disruption of the other Chs gene family members generated knockout mutants with diverse impacts on Fg. Comparative expression analyses revealed that among the Chs gene family members, Chs3b had the highest expression levels during Fg colonization of wheat. Three hairpin RNAi constructs corresponding to the different regions of Chs3b were found to silence Chs3b in transgenic Fg strains. Co-expression of these three RNAi constructs in two independent elite wheat cultivar transgenic lines conferred high levels of stable, consistent resistance (combined type I and II resistance) to both FHB and FSB throughout the T3 to T5 generations. Confocal microscopy revealed profoundly restricted mycelia in Fg-infected transgenic wheat plants. Presence of the three specific short interfering RNAs in transgenic wheat plants was confirmed by Northern blotting, and these RNAs efficiently down-regulated Chs3b in the colonizing Fusarium pathogens on wheat seedlings and spikes. Our results demonstrate that host-induced gene silencing of an essential fungal chitin synthase gene is an effective strategy for enhancing resistance in crop plants under field test conditions.

  15. RNAi mediated gene silencing against betasatellite associated with Croton yellow vein mosaic begomovirus.

    Science.gov (United States)

    Sahu, Anurag Kumar; Marwal, Avinash; Nehra, Chitra; Choudhary, Devendra Kumar; Sharma, Pradeep; Gaur, Rajarshi Kumar

    2014-11-01

    Plant viruses encode suppressors of posttranscriptional gene silencing, an adaptive antiviral defense responses that confines virus infection. Previously, we identified single-stranded DNA satellite (also known as DNA-β) of ~1,350 nucleotides in length associated with Croton yellow vein mosaic begomovirus (CYVMV) in croton plants. The expression of genes from DNA-β requires the begomovirus for packaged, replication, insect transmission and movement in plants. The present study demonstrates the effect of the βC1 gene on the silencing pathway as analysed by using both transgenic systems and transient Agrobacterium tumefaciens based delivery. Plants that carry an intron-hairpin construct covering the βC1 gene accumulated cognate small-interfering RNAs and remained symptom-free after exposure to CYVMV and its satellite. These results suggest that βC1 interferes with silencing mechanism.

  16. Short-term prediction of the influent quantity time series of wastewater treatment plant based on a chaos neural network model

    Institute of Scientific and Technical Information of China (English)

    LI Xiaodong; ZENG Guangming; HUANG Guohe; LI Jianbing; JIANG Ru

    2007-01-01

    By predicting influent quantity,a wastewater treatment plant (WWTP) can be well controlled.The nonlinear dynamic characteristic of WWTP influent quantity time series was analyzed,with the assumption that the series was predictable.Based on this,a short-term forecasting chaos neural network model of WWTP influent quantity was built by phase space reconstruction.Reasonable forecasting results were achieved using this method.

  17. The Short Fiction of Bobbie Ann Mason: Silent Voices, Silenced Voices, Voicing Silence.

    OpenAIRE

    Delgado Marín, Candela

    2015-01-01

    La presente tesis doctoral se enmarca dentro del campo de los estudios norteamericanos, centrándose en el relato breve de la escritora sureña Bobbie Ann Mason. El título de este proyecto apunta al foco de la investigación: el silencio. He utilizado tres puntos de vista diferentes para examinar los cuentos de esta escritora: el contexto socio-cultural, estudios comparativos literarios y teóricos y, por último, el análisis textual de su narrativa. Considero la producción literaria de Bobbie ...

  18. Virus-induced gene silencing in soybean and common bean.

    Science.gov (United States)

    Zhang, Chunquan; Whitham, Steven A; Hill, John H

    2013-01-01

    Plant viral vectors are useful for transient gene expression as well as for downregulation of gene expression via virus-induced gene silencing (VIGS). When used in reverse genetics approaches, VIGS offers a convenient way of transforming genomic information into knowledge of gene function. Efforts to develop and improve plant viral vectors have expanded their applications and have led to substantial advances needed to facilitate gene function studies in major row crops. Here, we describe a DNA-based Bean pod mottle virus (BPMV) vector system for both gene expression and VIGS in soybean and common bean.

  19. Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) Inhibits RNA-Mediated Gene Silencing by Targeting Ago-2.

    Science.gov (United States)

    Chen, Jing; Shi, Xibao; Zhang, Xiaozhuan; Wang, Li; Luo, Jun; Xing, Guangxu; Deng, Ruiguang; Yang, Hong; Li, Jinting; Wang, Aiping; Zhang, Gaiping

    2015-10-23

    Porcine reproductive and respiratory syndrome virus (PRRSV) infection strongly modulates the host's immune response. The RNA silencing pathway is an intracellular innate response to viral infections. However, it is unknown whether PRRSV interacts with cellular RNA silencing to facilitate the viral infection. Here, we report for the first time the interaction between PRRSV and RNA silencing in both the porcine macrophages and African green monkey kidney cell line (MARC-145) cell line, which were derived from African green monkey kidney cells and highly permissive for PRRSV infection. Our data demonstrated that PRRSV suppressed RNA silencing induced by short-hairpin (sh) RNA, double-strand (ds) RNA and microRNA (miRNA) and downregulated the expression of argonaute protein-2 (Ago-2), which is a key protein of the RNA silencing pathway in animal cells. Further, exogenous introduction of siRNA and shRNA downregulated Dicer or Ago-2 proteins of the cellular RNA silencing apparatus in MARC-145 cells and porcine macrophages, which, in turn, increased the viral replication and titers. The viral non-structure protein 1α (nsp-1α) and nsp11 of PRRSV were identified as the suppressors for cellular RNA silencing (RSSs) to downregulate the Ago-2 protein. Our results identify that PRRSV, through its nsp proteins, suppresses the cellular RNA silencing apparatus in favor of viral infection and supports a co-evolutionary process of the virus and the cellular RNA silencing process.

  20. Porcine Reproductive and Respiratory Syndrome Virus (PRRSV Inhibits RNA-Mediated Gene Silencing by Targeting Ago-2

    Directory of Open Access Journals (Sweden)

    Jing Chen

    2015-10-01

    Full Text Available Porcine reproductive and respiratory syndrome virus (PRRSV infection strongly modulates the host’s immune response. The RNA silencing pathway is an intracellular innate response to viral infections. However, it is unknown whether PRRSV interacts with cellular RNA silencing to facilitate the viral infection. Here, we report for the first time the interaction between PRRSV and RNA silencing in both the porcine macrophages and African green monkey kidney cell line (MARC-145 cell line, which were derived from African green monkey kidney cells and highly permissive for PRRSV infection. Our data demonstrated that PRRSV suppressed RNA silencing induced by short-hairpin (sh RNA, double-strand (ds RNA and microRNA (miRNA and downregulated the expression of argonaute protein-2 (Ago-2, which is a key protein of the RNA silencing pathway in animal cells. Further, exogenous introduction of siRNA and shRNA downregulated Dicer or Ago-2 proteins of the cellular RNA silencing apparatus in MARC-145 cells and porcine macrophages, which, in turn, increased the viral replication and titers. The viral non-structure protein 1α (nsp-1α and nsp11 of PRRSV were identified as the suppressors for cellular RNA silencing (RSSs to downregulate the Ago-2 protein. Our results identify that PRRSV, through its nsp proteins, suppresses the cellular RNA silencing apparatus in favor of viral infection and supports a co-evolutionary process of the virus and the cellular RNA silencing process.

  1. Specific degradation of 3' regions of GUS mRNA in posttranscriptionally silenced tobacco lines may be related to 5'-3' spreading of silencing

    DEFF Research Database (Denmark)

    Braunstein, Thomas Hartig; Moury, Benoit; Johannessen, Marina;

    2002-01-01

    Target regions for posttranscriptional silencing of transgenes often reside in the 3' region of the coding sequence, although there are exceptions. To resolve if the target region is determined by the gene undergoing silencing rather than by the structure of the transgene loci or the plant genetic...... background, we have performed detailed analyses of target regions in three spontaneously beta-glucuronidase (GUS) silencing tobacco lines of different origin. From quantitative cosuppression experiments, we show that the main target region in all three tobacco lines is found within the 3' half of the GUS...... coding region but upstream of the last 200 nt. The quantities of small (21-25 nt) RNAs homologous to 5' or 3' regions of the GUS coding sequence were found to correlate approximately with the target strength of the corresponding regions. These results suggest that transgene locus structure and plant...

  2. Short tandem target mimic: a long journey to the engineered molecular landmine for selective destruction/blockage of microRNAs in plants and animals.

    Science.gov (United States)

    Tang, Guiliang; Tang, Xiaoqing

    2013-06-20

    MicroRNAs (miRNAs) are a population of highly conserved specific small ribo-regulators that negatively regulate gene expressions in both plants and animals. They play a key role in post-transcriptional gene regulation by destabilizing the target gene transcripts or blocking protein translation from them. Interestingly, these negative regulators are largely compromised by an upstream layer of negative regulators "target mimics" found in plants or "endogenous competing RNAs" revealed recently in animals. These endogenous regulatory mechanisms of "double negatives making a positive" have now been developed into a key strategy in the study of small RNA functions. This review presents some reflections on the long journey to the short tandem target mimic (STTM) for selective destruction/blockage of specific miRNAs in plants and animals, and the potential applications of STTM are discussed.

  3. Short Tandem Target Mimic: A Long Journey to the Engineered Molecular Landmine for Selective Destruction/Blockage of MicroRNAs in Plants and Animals

    Institute of Scientific and Technical Information of China (English)

    Guiliang Tang; Xiaoqing Tang

    2013-01-01

    MicroRNAs (miRNAs) are a population of highly conserved specific small ribo-regulators that negatively regulate gene expressions in both plants and animals.They play a key role in post-transcriptional gene regulation by destabilizing the target gene transcripts or blocking protein translation from them.Interestingly,these negative regulators are largely compromised by an upstream layer of negative regulators “target mimics” found in plants or “endogenous competing RNAs” revealed recently in animals.These endogenous regulatory mechanisms of “double negatives making a positive” have now been developed into a key strategy in the study of small RNA functions.This review presents some reflections on the long journey to the short tandem target mimic (STTM) for selective destruction/blockage of specific miRNAs in plants and animals,and the potential applications of STTM are discussed.

  4. [E. M. Jellinek's silenced and silencing transgenerational story].

    Science.gov (United States)

    Kelemen, Gábor; Márk, Mónika

    2013-01-01

    Jellinek is a kind of archetypal character for future generations in the field of addiction studies. His implosion in the arena of alcoholism around the age of 50 was an unexpected challenge to medical science. We know very little about his own role models giving an intellectual and moral compass to his pragmatic creativity. More than 30 years has passed since Jellinek's death when an American sociologist Ron Roizen started unearthing his silent story. Roizen discerned that there are a lot of unsaid and muted issues in his personal Hungarian past. Our paper, based on the authors' research in Hungarian archives and other sources reveals that not just Jellinek's personal but his transgenerational narrative has been not-yet-said. This silenced and silencing history appears an unfinished business of acculturation of the family, which started prior to four generations. Authors have been concluding that the issue of religious conversion is a critical point in the process of acculturation. They examine the counter move of loyalty to family values and driving force of assimilation making their story unspeakable.

  5. HIV-1 Tat RNA silencing suppressor activity is conserved across kingdoms and counteracts translational repression of HIV-1.

    Science.gov (United States)

    Qian, Shuiming; Zhong, Xuehua; Yu, Lianbo; Ding, Biao; de Haan, Peter; Boris-Lawrie, Kathleen

    2009-01-13

    The RNA silencing pathway is an intracellular innate response to virus infections and retro-transposons. Many plant viruses counter this host restriction by RNA silencing suppressor (RSS) activity of a double-stranded RNA-binding protein, e.g., tomato bushy stunt virus P19. Here, we demonstrate P19 and HIV-1 Tat function across the plant and animal kingdoms and suppress a common step in RNA silencing that is downstream of small RNA maturation. Our experiments reveal that RNA silencing in HIV-1 infected human cells severely attenuates the translational output of the unspliced HIV-1 gag mRNA, and possibly all HIV-1 transcripts. The attenuation in gag mRNA translation is exacerbated by K51A substitution in the Tat double-stranded RNA-binding domain. Tat, plant virus RSS, or Dicer downregulation rescues robust gag translation and bolsters HIV-1 virion production. The reversal of HIV-1 translation repression by plant RSS supports the recent finding in Arabidopsis that plant miRNAs operate by translational inhibition. Our results identify common features between RNA silencing suppression of plant and animal viruses. We suggest that RNA silencing-mediated translation repression plays a strategic role in determining the viral set-point in a newly HIV-1-infected patient.

  6. Silence

    Science.gov (United States)

    Cogswell, J.

    2011-06-01

    On the occasion of the International Year of Astronomy, I was commissioned to create a mural for the University of Michigan Department of Astronomy, responding to an array of scientific images based on astronomical research, with special focus on the work of University of Michigan astronomers carried out within the building. My paper illustrates the development of this and several subsequent projects, explaining the implications for my artistic practice of entering into this conversation with astronomers and their work.

  7. Probing the MicroRNA and Small Interfering RNA Pathways with Virus-Encoded Suppressors of RNA SilencingW⃞

    Science.gov (United States)

    Dunoyer, Patrice; Lecellier, Charles-Henri; Parizotto, Eneida Abreu; Himber, Christophe; Voinnet, Olivier

    2004-01-01

    In plants, small interfering RNAs (siRNAs) and microRNAs (miRNAs) are effectors of RNA silencing, a process involved in defense through RNA interference (RNAi) and in development. Plant viruses are natural targets of RNA silencing, and as a counterdefensive strategy, they have evolved highly diverse silencing suppressor proteins. Although viral suppressors are usually thought to act at distinct steps of the silencing machinery, there had been no consensus system so far that allowed a strict side-by-side analysis of those factors. We have set up such a system in Arabidopsis thaliana and used it to compare the effects of five unrelated viral silencing suppressors on the siRNA and miRNA pathways. Although all the suppressors inhibited RNAi, only three of them induced developmental defects, indicating that the two pathways are only partially overlapping. These developmental defects were remarkably similar, and their penetrance correlated with inhibition of miRNA-guided cleavage of endogenous transcripts and not with altered miRNA accumulation per se. Among the suppressors investigated, the tombusviral P19 protein coimmunoprecipitated with siRNA duplexes and miRNA duplexes corresponding to the primary cleavage products of miRNA precursors. Thus, it is likely that P19 prevents RNA silencing by sequestering both classes of small RNAs. Moreover, the finding here that P19 binds siRNAs and suppresses RNAi in Hela cells also suggests that this factor may be useful to dissect the RNA silencing pathways in animals. Finally, the differential effects of the silencing suppressors tested here upon other types of Arabidopsis silencing-related small RNAs revealed a surprising variety of biosynthetic and, presumably, functional pathways for those molecules. Therefore, silencing suppressors are valuable probes of the complexity of RNA silencing. PMID:15084715

  8. Short range attraction of Ceratitis capitata (Diptera: Tephritidae) sterile males to six commercially available plant essential oils

    Science.gov (United States)

    Plant essential oils have a number of roles in insect pest management. For male Ceratitis capitata, this includes use of angelica seed oil as long range attractants and ginger root oil as aromatherapy, which is exposure to sterile males to increase mating success. Neither of these plants are hosts f...

  9. "The Silence Itself Is Enough of a Statement": The Day of Silence and LGBTQ Awareness Raising

    Science.gov (United States)

    Woolley, Susan W.

    2012-01-01

    This ethnographic study of a high school gay-straight alliance club examines unintended consequences of silence during the Day of Silence, a day of action aimed at addressing anti-LGBTQ bias in schools. While this strategy calls for students to engage in intentional silences to raise awareness of anti-LGBTQ bias, it does not necessarily lead…

  10. "The Silence Itself Is Enough of a Statement": The Day of Silence and LGBTQ Awareness Raising

    Science.gov (United States)

    Woolley, Susan W.

    2012-01-01

    This ethnographic study of a high school gay-straight alliance club examines unintended consequences of silence during the Day of Silence, a day of action aimed at addressing anti-LGBTQ bias in schools. While this strategy calls for students to engage in intentional silences to raise awareness of anti-LGBTQ bias, it does not necessarily lead…

  11. A viral suppressor protein inhibits host RNA silencing by hooking up with Argonautes

    KAUST Repository

    Jin, Hailing

    2010-05-01

    RNA viruses are particularly vulnerable to RNAi-based defenses in the host, and thus have evolved specific proteins, known as viral suppressors of RNA silencing (VSRs), as a counterdefense. In this issue of Genes & Development, Azevedo and colleagues (pp. 904-915) discovered that P38, the VSR of Turnip crinkle virus, uses its glycine/tryptophane (GW) motifs as an ARGONAUTE (AGO) hook to attract and disarm the host\\'s essential effector of RNA silencing. Several GW motif-containing cellular proteins are known to be important partners of AGOs in RNA silencing effector complexes in yeast, plants, and animals. The GW motif appears to be a versatile and effective tool for regulating the activities of RNA silencing pathways, and the use of GW mimicry to compete for and inhibit host AGOs may be a strategy used by many pathogens to counteract host RNAi-based defenses. © 2010 by Cold Spring Harbor Laboratory Press.

  12. Two suppressors of RNA silencing encoded by cereal-infecting members of the family Luteoviridae.

    Science.gov (United States)

    Liu, Yan; Zhai, Hao; Zhao, Kun; Wu, Beilei; Wang, Xifeng

    2012-08-01

    Several members of the family Luteoviridae are important pathogens of cultivated plant species of the family Gramineae. In this study, we explored RNA-silencing suppressors (RSSs) encoded by two cereal-infecting luteoviruses: barley yellow dwarf virus and wheat yellow dwarf virus (BYDV and WYDV, respectively). The P0 protein of WYDV-GPV (P0(GPV)) and the P6 protein of BYDV-GAV (P6(GAV)) displayed RSS activities when expressed in agro-infiltrated leaves of Nicotiana benthamiana, by their local ability to inhibit post-transcriptional gene silencing of GFP. Analysis of GFP, mRNA and GFP-specific small interfering RNA indicated that both P0(GPV) and P6(GAV) are suppressors of silencing that can restrain not only local but also systemic gene silencing. This is the first report of RSS activity of the P6 protein in a member of the genus Luteovirus.

  13. Stability of Barley stripe mosaic virus induced gene silencing in barley

    DEFF Research Database (Denmark)

    Bruun-Rasmussen, Marianne; Madsen, Christian Toft; Jessing, Stine

    2007-01-01

    Virus-induced gene silencing (VIGS) can be used as a powerful tool for functional genomics studies in plants. With this approach, it is possible to target most genes and downregulate the messenger (m)RNA in a sequence-specific manner. Barley stripe mosaic virus (BSMV) is an established VIGS vector...... for barley and wheat; however, silencing using this vector is generally transient, with efficient silencing often being confined to the first two or three systemically infected leaves. To investigate this further, part of the barley Phytoene desaturase (PDS) gene was inserted into BSMV and the resulting...... inoculation, although large parts of the insert had been lost from the virus vector. The instability of the insert, observed consistently throughout our experiments, offers an explanation for the transient nature of silencing when using BSMV as a VIGS vector....

  14. Has medical education killed "silence"?

    Science.gov (United States)

    Lee, Shuh Shing

    2017-04-01

    There is an ignorance of "silence" observed from student selection methods to teaching and learning approaches. While selecting the candidates with suitable values to medical schools is crucial, most methods are unable to address fairness issue toward students from some disadvantaged background or certain personality specifically introversion. Similarly, teaching and learning approaches have shifted away from didactic to a more discursive methods such as brainstorming, team-based learning and case-based learning. These methods emphasize active participation and communication with team members, but having more discussion does not indicate that deep learning has taken place. Majority of these approaches require students to complete a task within an allocated time frame. Therefore, most of the time is utilized to complete a task instead of learning how to acquire a skill or learning how to learn. Important "silent" skills such as observation, reasoning process, and listening skills, are given less time or almost none due to time constraint within these discursive approaches, although these skills are extremely important as a doctor. Hence, it is time to think about on how best to balance the use of silence and externalize thought processes in medical education.

  15. An efficient viral vector for functional genomic studies of Prunus fruit trees and its induced resistance to Plum pox virus via silencing of a host factor gene

    OpenAIRE

    Cui, Hongguang; Wang, Aiming

    2016-01-01

    Summary RNA silencing is a powerful technology for molecular characterization of gene functions in plants. A commonly used approach to the induction of RNA silencing is through genetic transformation. A potent alternative is to use a modified viral vector for virus?induced gene silencing (VIGS) to degrade RNA molecules sharing similar nucleotide sequence. Unfortunately, genomic studies in many allogamous woody perennials such as peach are severely hindered because they have a long juvenile pe...

  16. Short-term salinity stress in tobacco plants leads to the onset of animal-like PCD hallmarks in planta in contrast to long-term stress.

    Science.gov (United States)

    Andronis, Efthimios A; Roubelakis-Angelakis, Kalliopi A

    2010-01-01

    Recent results have identified mitochondria as centers of stress-induced generation of reactive oxygen species in plants. Depolarization of plant mitochondrial membrane during stress results the release of programmed cell death (PCD)-inducing factors in the cytosol in a fashion similar to the onset of animal-like PCD. Herein, we report significant similarities of animal-like PCD and salinity stress-induced plant PCD. Short-term salinity stress (3 h) led to depolarization of the mitochondrial membrane, release of cytochrome c (CYT-c), which was visualized using a contemporary molecular technique, activation of caspase-3 type proteases and the onset of PCD in wild type tobacco plants, Nicotiana tabacum cv. Petit Havana. However, PCD was not manifested during long-term salinity stress (24 h). Interestingly long-term salinity stress led to necrotic-like features, which were accompanied by collapse of respiration, reduction of key components of the respiratory chain, such as CYT-c and alternative oxidase, ATP depletion and high proteolytic activity. The results suggest that salinity stress of tobacco plants in planta leads to the onset of animal-like PCD only during the early stages post-stress, while long-term stress leads to necrotic-like features.

  17. Dispersion of Short- and Medium-Chain Chlorinated Paraffins (CPs) from a CP Production Plant to the Surrounding Surface Soils and Coniferous Leaves.

    Science.gov (United States)

    Xu, Jiazhi; Gao, Yuan; Zhang, Haijun; Zhan, Faqiang; Chen, Jiping

    2016-12-06

    Chlorinated paraffin (CP) production is one important emission source for short- and medium-chain CPs (SCCPs and MCCPs) in the environment. In this study, 48 CP congener groups were measured in the surface soils and coniferous leaves collected from the inner and surrounding environment of a CP production plant that has been in operation for more than 30 years to investigate the dispersion and deposition behavior of SCCPs and MCCPs. The average concentrations of the sum of SCCPs and MCCPs in the in-plant coniferous leaves and surface soils were 4548.7 ng g(-1) dry weight (dw) and 3481.8 ng g(-1) dw, which were 2-fold and 10-fold higher than those in the surrounding environment, respectively. The Gaussian air pollution model explained the spatial distribution of CPs in the coniferous leaves, whereas the dispersion of CPs to the surrounding surface soils fits the Boltzmann equation well. Significant fractionation effect was observed for the atmospheric dispersion of CPs from the production plant. CP congener groups with higher octanol-air partitioning coefficients (KOA) were more predominant in the in-plant environment, whereas the ones with lower KOA values had the elevated proportion in the surrounding environment. A radius of approximately 4 km from the CP production plant was influenced by the atmospheric dispersion and deposition of CPs.

  18. The operation of small cogeneration plants and short-term storage for district heating and public electric power

    DEFF Research Database (Denmark)

    Ilkjær, J; Petersen, P.M.; Qvale, Einar Bjørn

    1989-01-01

    A theoretical investigation of the economics of cogeneration supplemented by warm-water storage and subjected to a three-step price schedule for electricity, has been carried out. Some general guidelines can be derived, but no simple design rules, such as those for cogeneration plants operating...... with a two-step schedule, seem to govern the design of such plants subjected to the new conditions. Simulation studies have been initiated in order to arrive at sufficiently accurate optimal store dimensions and operational strategy. The results from simulation studies which give the store as a function...... of cogeneration plant size relative to the total heat demand in the geographical region supplied by the plant are shown...

  19. A Continuing Education Short Course and Engineering Curriculum to Accelerate Workforce Development in Wind Power Plant Design, Construction, and Operations

    Energy Technology Data Exchange (ETDEWEB)

    Tinjum, James [Univ. of Wisconsin, Madison, WI (United States)

    2012-11-29

    Significant advances in wind turbine technology and wind turbine power plant capabilities are appearing in the U.S. Sites that only 10 years ago might have been overlooked are being considered for build out. However, the development of a skilled workforce in the engineering fields and construction trades lags the potential market, especially if the industry is expected to site, design, construct, and operate sufficient wind power plant sites to meet the potential for 20% wind energy by 2030. A select few firms have penetrated the engineer-procure-construction (EPC) market of wind power plant construction. Competition and know-how in this market is vital to achieve cost-effective, design-construct solutions. The industry must produce or retrain engineers, contractors, and technicians to meet ambitious goals. Currently, few universities offer undergraduate or graduate classes that teach the basics in designing, building, and maintaining wind power plants that are safe, efficient, and productive.

  20. Paramutation phenomena in plants.

    Science.gov (United States)

    Pilu, Roberto

    2015-08-01

    Paramutation is a particular epigenetic phenomenon discovered in Zea mays by Alexander Brink in the 1950s, and then also found in other plants and animals. Brink coined the term paramutation (from the Greek syllable "para" meaning beside, near, beyond, aside) in 1958, with the aim to differentiate paramutation from mutation. The peculiarity of paramutation with respect to other gene silencing phenomena consists in the ability of the silenced allele (named paramutagenic) to silence the other allele (paramutable) present in trans. The newly silenced (paramutated) allele remains stable in the next generations even after segregation from the paramutagenic allele and acquires paramutagenic ability itself. The inheritance behaviour of these epialleles permits a fast diffusion of a particular gene expression level/phenotype in a population even in the absence of other evolutionary influences, thus breaking the Hardy-Weinberg law. As with other gene silencing phenomena such as quelling in the fungus Neurospora crassa, transvection in Drosophila, co-suppression and virus-induced gene silencing (VIGS) described in transgenic plants and RNA interference (RNAi) in the nematode Caenorhabditis elegans, paramutation occurs without changes in the DNA sequence. So far the molecular basis of paramutation remains not fully understood, although many studies point to the involvement of RNA causing changes in DNA methylation and chromatin structure of the silenced genes. In this review I summarize all paramutation phenomena described in plants, focusing on the similarities and differences between them.

  1. Silences Which Elicit Reversals in Business Meetings.

    Science.gov (United States)

    Wasson, Christina

    An ethnographic and linguistic study conducted at a high-technology corporation examined decision-making in managerial meetings, focusing on the effects of silences following a proposal on the maker of the proposal. An opinion is that such silences signify a negative evaluation of the proposal, inviting the proposal maker to alter his position.…

  2. Classroom Silence: Voices from Japanese EFL Learners

    Science.gov (United States)

    Harumi, Seiko

    2011-01-01

    This article explores Japanese EFL learners' classroom silence in a Japanese EFL context. The existence of silence in second language learning contexts can be a source of conflict between students and teachers and even among students themselves. It can also be an obstacle to acquiring the target language. In order to tackle this problem and to…

  3. Silence as the voice of trauma.

    Science.gov (United States)

    Ritter, Maria

    2014-06-01

    Silence is a key to the unspoken world of the patient. Rather than interpreting silence as a defensive maneuver, the analyst may understand this disruption as a royal road to the patient's traumatic experiences. The author proposes to recognize traumatic silences in the analytic process and the transference as a re-experiencing of past, unpredictable traumatic affective states and memories. Silences in this context are both a repeat of a disconnecting experience as well as a manifestation of a silencing identification with the original silencer. The clinical material illustrates effects of a German mother's World War II (WWII) personal traumata and collective shame-based silence on her daughter's self and good object development. In the daughter's analysis, the patient and the analyst, who herself experienced similar WWII traumata, face the pain of trauma recovery and un-silencing. The author suggests that the deadening effect of past traumata may be reversed by an analytic process of re-membering and re-speaking for both the patient and analyst. This allows for a more transparent, subjective experience in the transference and a verbal integration of ego functions.

  4. Venturis as silencers in a BOF stack

    Energy Technology Data Exchange (ETDEWEB)

    Kelsall, T.; Gerritsen, T. [Hatch Associates Ltd., Mississauga, Ontario (Canada). Acoustics and Noise Control Dept.; Landon, T. [Wheeling-Pittsburgh Steel Corp., Steubenville, OH (United States)

    1995-06-01

    Installation of a venture in a BOF stack reduced the sound level in a local community by 10 to 15 db. This application resulted in the development of a new type of fan silencer, called the modal silencer, having the inherent advantages of low pressure drop and less maintenance compared with conventional types.

  5. Communication to Enhance Silence: The Trappist Experience

    Science.gov (United States)

    Jaksa, James A.; Stech, Ernest L.

    1978-01-01

    Investigates perceptions of the amount of interpersonal communication and attitudes towards communication frequency after the Trappist monk's rule of enforced silence and solitude was lifted in 1969. Concludes that increased interpersonal communication resulted in increased self-awareness and therefore more meaningful and effective silence. (MH)

  6. Silence in Cross-cultural Communication

    Institute of Scientific and Technical Information of China (English)

    常利娜; 郭芳芳; 郝继亭; 顾庆媛; 孙胜强

    2008-01-01

    In academic field, silence is classified as part of the nonverbal communication. Edward T. Hall regarded silence as a key standard of dividing high-context cultures and low-context cultures (毕 46). In high-context cultures, information is provided through gestures, the use of space, and even silence. Little information is explicitly explained by words. Chinese, Japanese, Native American cultures are high-context ones. However, "in low-context cultures, the verbal message contains most of the information and very little is embedded in the context." (Samovar, A. Larry, Richard E. Porter and Lisa A. Stefani 79). How do people from different cultures respond to silence? How their values affect their attitudes? What causes silence?

  7. Short-term effects of compost amendment on the fractionation of cadmium in soil and cadmium accumulation in rice plants.

    Science.gov (United States)

    Juang, Kai-Wei; Ho, Pei-Chi; Yu, Chun-Hui

    2012-06-01

    We used a sequential extraction to investigate the effects of compost amendment on Cd fractionation in soil during different incubation periods in order to assess Cd stabilization in soil over time. Pot experiments using rice plants growing on Cd-spiked soils were carried out to evaluate the influence of compost amendment on plant growth and Cd accumulation by rice. Two agricultural soils (Pinchen and Lukang) of Taiwan were used for the experiments. The relationship between the redistribution of Cd fractions and the reduction of plant Cd concentration due to compost amendment was then investigated. Compost amendment in Pinchen soil (lower pH) could transform exchangeable Cd into the Fe- and Mn-oxide-bound forms. With increasing incubation time, exchangeable Cd tended to transform into carbonate- and Fe- and Mn-oxide-bound fractions. In Lukang soil (higher pH), carbonate- and Fe- and Mn-oxide-bonded Cd were the main fractions. Exchangeable Cd was low. Compost amendment transformed the carbonate-bound form into the Fe and Mn oxide form. Pot experiments of rice plants showed that compost amendment enhanced plant growth more in Pinchen soil than in Lukang soil. Compost amendment could significantly reduce Cd accumulation in rice roots in both Pinchen and Lukang soils and restrict internal transport of Cd from the roots to the shoots. Because exchangeable Cd can be transformed into the stronger bonded fractions quickly in Pinchen soil, a reduction of Cd accumulation in rice due to compost amendment of Pinchen soil was significant by 45 days of growth. However, carbonate-bonded fractions in Lukang soil may provide a source of available Cd to rice plants, and exchangeable and carbonate-bonded fractions are transformed into the other fractions slowly. Thus, reduction of Cd accumulation by rice due to compost amendment in Lukang soil was significant by 75 days of growth. The results of the study suggest that the effectiveness of compost amendment used for stabilization of

  8. ARBRE monitoring - ecology of short rotation coppice. Four year study involving wildlife monitoring of commercial SCR plantations planted on arable land and arable control plots

    Energy Technology Data Exchange (ETDEWEB)

    Cunningham, M.D.; Bishop, J.D.; McKay, H.V.; Sage, R.B.

    2004-07-01

    This report summarises the findings of the UK Department of Trade and Industry (DTI) funded project monitoring wildlife within and around a number of commercially managed Short Rotation Coppice (SRC) plantations aimed at using the information gathered to assess the ecological impact of SRC plantations on the wildlife in the area. The background to the study is traced, and details are given of the monitoring programme examining the distribution of flora and fauna within the plantations, and the monitoring of birds, plants, insects and butterflies. The greater diversity of wildlife and plants in the SRC plots, the higher densities of birds, and the increasing number of butterfly species are discussed along with the increased mean number of invertebrate orders with subsequent growth of willow coppices, and the habitats at the edges of the plots and at headlands designed for access to machinery within the plots.

  9. Short-day treatment during the growing period limits shoot growth and increases frost hardiness of hybrid aspen plants in the nursery

    Institute of Scientific and Technical Information of China (English)

    Zhang Gang; Jaana Luoranen; Heikki Smolander

    2007-01-01

    In Finland, under nursery conditions hybrid aspen may continue their shoot growth until early September. Thus,frost hardening is usually delayed. To solve this problem, We used a three-week period of short-day (SD) treatment between late July and mid-August. During autumn after frost exposure,frost hardiness (FH) Was assessed three times with a stem-browning test. The resuits showed that after SD treatment shoot growth ceased and FH increased when compared to untreated hybrid aspen. Furthermore,the height of SD-treated hybrid aspen varied much less than that of the control plants. We conclude that SD treatment in the nursery during the growing period can be used as a supplementary method for producing well-hardened and uniform hybrid aspen plants.

  10. Phenotyping of VIGS-mediated gene silencing in rice using a vector derived from a DNA virus.

    Science.gov (United States)

    Kant, Ravi; Dasgupta, Indranil

    2017-07-01

    Target genes in rice can be optimally silenced if inserted in antisense or hairpin orientation in the RTBV-derived VIGS vector and plants grown at 28 °C and 80% humidity after inoculation. Virus induced gene silencing (VIGS) is a method used to transiently silence genes in dicot as well as monocot plants. For the important monocot species rice, the Rice tungro bacilliform virus (RTBV)-derived VIGS system (RTBV-VIGS), which uses agroinoculation to initiate silencing, has not been standardized for optimal use. Here, using RTBV-VIGS, three sets of conditions were tested to achieve optimal silencing of the rice marker gene phytoene desaturase (pds). The effect of orientation of the insert in the RTBV-VIGS plasmid (sense, antisense and hairpin) on the silencing of the target gene was then evaluated using rice magnesium chelatase subunit H (chlH). Finally, the rice Xa21 gene, conferring resistance against bacterial leaf blight disease (BLB) was silenced using RTBV-VIGS system. In each case, real-time PCR-based assessment indicated approximately 40-80% fall in the accumulation levels of the transcripts of pds, chlH and Xa21. In the case of pds, the appearance of white streaks in the emerging leaves, and for chlH, chlorophyll levels and F v/F m ratio were assessed as phenotypes for silencing. For Xa21, the resistance levels to BLB were assessed by measuring the lesion length and the percent diseased areas of leaves, following challenge inoculation with Xanthomonas oryzae. In each case, the RTBV-MVIGS system gave rise to a discernible phenotype indicating the silencing of the respective target gene using condition III (temperature 28 °C, humidity 80% and 1 mM MES and 20 µM acetosyringone in secondary agrobacterium culture), which revealed the robustness of this gene silencing system for rice.

  11. Glucose-6-phosphate dehydrogenase plays a central role in the response of tomato (Solanum lycopersicum) plants to short and long-term drought.

    Science.gov (United States)

    Landi, Simone; Nurcato, Roberta; De Lillo, Alessia; Lentini, Marco; Grillo, Stefania; Esposito, Sergio

    2016-08-01

    The present study was undertaken to investigate the expression, occurrence and activity of glucose 6 phosphate dehydrogenase (G6PDH - EC 1.1.1.49), the key-enzyme of the Oxidative Pentose Phosphate Pathway (OPPP), in tomato plants (Solanum lycopersicum cv. Red Setter) exposed to short- and long-term drought stress. For the first time, drought effects have been evaluated in plants under different growth conditions: in hydroponic laboratory system, and in greenhouse pots under controlled conditions; and in open field, in order to evaluate drought response in a representative agricultural environment. Interestingly, changes observed appear strictly associated to the induction of well known stress response mechanisms, such as the increase of proline synthesis, accumulation of chaperone Hsp70, and ascorbate peroxidase. Results show significant increase in total activity of G6PDH, and specifically in expression and occurrence of cytosolic isoform (cy-G6PDH) in plants grown in any cultivation system upon drought. Intriguingly, the results clearly suggest that abscissic acid (ABA) pathway and signaling cascade (protein phosphatase 2C PP2C) could be strictly related to increased G6PDH expression, occurrence and activities. We hypothesized for G6PDH a specific role as one of the main reductants' suppliers to counteract the effects of drought stress, in the light of converging evidences given by young and adult tomato plants under stress of different duration and intensity. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  12. Predictable 'meta-mechanisms' emerge from feedbacks between transpiration and plant growth and cannot be simply deduced from short-term mechanisms.

    Science.gov (United States)

    Tardieu, François; Parent, Boris

    2016-08-29

    Growth under water deficit is controlled by short-term mechanisms but, because of numerous feedbacks, the combination of these mechanisms over time often results in outputs that cannot be deduced from the simple inspection of individual mechanisms. It can be analysed with dynamic models in which causal relationships between variables are considered at each time-step, allowing calculation of outputs that are routed back to inputs for the next time-step and that can change the system itself. We first review physiological mechanisms involved in seven feedbacks of transpiration on plant growth, involving changes in tissue hydraulic conductance, stomatal conductance, plant architecture and underlying factors such as hormones or aquaporins. The combination of these mechanisms over time can result in non-straightforward conclusions as shown by examples of simulation outputs: 'over production of abscisic acid (ABA) can cause a lower concentration of ABA in the xylem sap ', 'decreasing root hydraulic conductance when evaporative demand is maximum can improve plant performance' and 'rapid root growth can decrease yield'. Systems of equations simulating feedbacks over numerous time-steps result in logical and reproducible emergent properties that can be viewed as 'meta-mechanisms' at plant level, which have similar roles as mechanisms at cell level.

  13. PhCESA3 silencing inhibits elongation and stimulates radial expansion in petunia

    Science.gov (United States)

    Yang, Weiyuan; Cai, Yuanping; Hu, Li; Wei, Qian; Chen, Guoju; Bai, Mei; Wu, Hong; Liu, Juanxu; Yu, Yixun

    2017-01-01

    Cellulose synthase catalytic subunits (CESAs) play important roles in plant growth, development and disease resistance. Previous studies have shown an essential role of Arabidopsis thaliana CESA3 in plant growth. However, little is known about the role of CESA3 in species other than A. thaliana. To gain a better understanding of CESA3, the petunia (Petunia hybrida) PhCESA3 gene was isolated, and the role of PhCESA3 in plant growth was analyzed in a wide range of plants. PhCESA3 mRNA was present at varying levels in tissues examined. VIGS-mediated PhCESA3 silencing resulted in dwarfing of plant height, which was consistent with the phenotype of the A. thaliana rsw1 mutant (a temperature-sensitive allele of AtCESA1), the A. thaliana cev1 mutant (the AtCESA3 mild mutant), and the antisense AtCESA3 line. However, PhCESA3 silencing led to swollen stems, pedicels, filaments, styles and epidermal hairs as well as thickened leaves and corollas, which were not observed in the A. thaliana cev1 mutant, the rsw1 mutant and the antisense AtCESA3 line. Further micrographs showed that PhCESA3 silencing reduced the length and increased the width of cells, suggesting that PhCESA3 silencing inhibits elongation and stimulates radial expansion in petunia. PMID:28150693

  14. Calibration and validation of models for short-term decomposition and N mineralization of plant residues in the tropics

    NARCIS (Netherlands)

    Nascimento, do A.F.; Mendona, E.D.; Leite, L.F.C.; Scholberg, J.M.S.; Neves, J.C.L.

    2012-01-01

    Insight of nutrient release patterns associated with the decomposition of plant residues is important for their effective use as a green manure in food production systems. Thus, this study aimed to evaluate the ability of the Century, APSIM and NDICEA simulation models for predicting the decompositi

  15. A Study on the Tritium Behavior in the Rice Plant after a Short-Term Exposure of HTO

    Energy Technology Data Exchange (ETDEWEB)

    Yook, D-S.; Lee, K. J.; Choi, Y-H.

    2002-02-26

    In many Asian countries including Korea, rice is a very important food crop. Its grain is consumed by humans and its straw is used to feed animals. In Korea, there are four CANDU type reactors that release relatively large amounts of tritium into the environment. Since 1997, KAERI (Korea Atomic Energy Research Institute) has carried out the experimental studies to obtain domestic data on various parameters concerning the direct contamination of plant. In this study, the behavior of tritium in the rice plant is predicted and compared with the measurement performed at KAERI. Using the conceptual model of the soil-plant-atmosphere tritiated water transport system which was suggested by Charles E. Murphy, tritium concentrations in the soil and in leaves to time were derived. If the effect of tritium concentration in the soil is considered, the tritium concentration in leaves is described as a double exponential model. On the other hand if the tritium concentration in the soil is disregarded, the tritium concentration in leaves is described by a single exponential term as other models (e.g. Belot's or STAR-H3 model). Also concentration of organically bound tritium in the seed is predicted and compared with measurements. The results can be used to predict the tritium concentration in the rice plant at a field around the site and the ingestion dose following the release of tritium to the environment.

  16. Calibration and validation of models for short-term decomposition and N mineralization of plant residues in the tropics

    NARCIS (Netherlands)

    Nascimento, do A.F.; Mendona, E.D.; Leite, L.F.C.; Scholberg, J.M.S.; Neves, J.C.L.

    2012-01-01

    Insight of nutrient release patterns associated with the decomposition of plant residues is important for their effective use as a green manure in food production systems. Thus, this study aimed to evaluate the ability of the Century, APSIM and NDICEA simulation models for predicting the

  17. Primary and secondary siRNAs in geminivirus-induced gene silencing.

    Directory of Open Access Journals (Sweden)

    Michael Aregger

    2012-09-01

    Full Text Available In plants, RNA silencing-based antiviral defense is mediated by Dicer-like (DCL proteins producing short interfering (siRNAs. In Arabidopsis infected with the bipartite circular DNA geminivirus Cabbage leaf curl virus (CaLCuV, four distinct DCLs produce 21, 22 and 24 nt viral siRNAs. Using deep sequencing and blot hybridization, we found that viral siRNAs of each size-class densely cover the entire viral genome sequences in both polarities, but highly abundant siRNAs correspond primarily to the leftward and rightward transcription units. Double-stranded RNA precursors of viral siRNAs can potentially be generated by host RDR-dependent RNA polymerase (RDR. However, genetic evidence revealed that CaLCuV siRNA biogenesis does not require RDR1, RDR2, or RDR6. By contrast, CaLCuV derivatives engineered to target 30 nt sequences of a GFP transgene by primary viral siRNAs trigger RDR6-dependent production of secondary siRNAs. Viral siRNAs targeting upstream of the GFP stop codon induce secondary siRNAs almost exclusively from sequences downstream of the target site. Conversely, viral siRNAs targeting the GFP 3'-untranslated region (UTR induce secondary siRNAs mostly upstream of the target site. RDR6-dependent siRNA production is not necessary for robust GFP silencing, except when viral siRNAs targeted GFP 5'-UTR. Furthermore, viral siRNAs targeting the transgene enhancer region cause GFP silencing without secondary siRNA production. We conclude that the majority of viral siRNAs accumulating during geminiviral infection are RDR1/2/6-independent primary siRNAs. Double-stranded RNA precursors of these siRNAs are likely generated by bidirectional readthrough transcription of circular viral DNA by RNA polymerase II. Unlike transgenic mRNA, geminiviral mRNAs appear to be poor templates for RDR-dependent production of secondary siRNAs.

  18. Silencing of grapevine pectate lyase-like genes VvPLL2 and VvPLL3 confers resistance against Erysiphe necator and differentially modulates gene expression

    Science.gov (United States)

    Broad-spectrum resistance against powdery mildew (PM) has been reported by silencing susceptibility genes in the model plant Arabidopsis. Here we used artificial microRNA constructs in PM-susceptible Vitis vinifera cv. Chardonnay to stably silence two pectate lyase-like orthologs (VvPLL2 and VvPLL3)...

  19. The Nuclear Cap-Binding Complex Mediates Meiotic Silencing by Unpaired DNA

    Science.gov (United States)

    Decker, Logan M.; Xiao, Hua; Boone, Erin C.; Vierling, Michael M.; Shanker, Benjamin S.; Kingston, Shanika L.; Boone, Shannon F.; Haynes, Jackson B.; Shiu, Patrick K.T.

    2017-01-01

    In the filamentous fungus Neurospora crassa, cross walls between individual cells are normally incomplete, making the entire fungal network vulnerable to attack by viruses and selfish DNAs. Accordingly, several genome surveillance mechanisms are maintained to help the fungus combat these repetitive elements. One of these defense mechanisms is called meiotic silencing by unpaired DNA (MSUD), which identifies and silences unpaired genes during meiosis. Utilizing common RNA interference (RNAi) proteins, such as Dicer and Argonaute, MSUD targets mRNAs homologous to the unpaired sequence to achieve silencing. In this study, we have identified an additional silencing component, namely the cap-binding complex (CBC). Made up of cap-binding proteins CBP20 and CBP80, CBC associates with the 5′ cap of mRNA transcripts in eukaryotes. The loss of CBC leads to a deficiency in MSUD activity, suggesting its role in mediating silencing. As confirmed in this study, CBC is predominantly nuclear, although it is known to travel in and out of the nucleus to facilitate RNA transport. As seen in animals but not in plants, CBP20’s robust nuclear import depends on CBP80 in Neurospora. CBC interacts with a component (Argonaute) of the perinuclear meiotic silencing complex (MSC), directly linking the two cellular factors. PMID:28179391

  20. The Nuclear Cap-Binding Complex Mediates Meiotic Silencing by Unpaired DNA

    Directory of Open Access Journals (Sweden)

    Logan M. Decker

    2017-04-01

    Full Text Available In the filamentous fungus Neurospora crassa, cross walls between individual cells are normally incomplete, making the entire fungal network vulnerable to attack by viruses and selfish DNAs. Accordingly, several genome surveillance mechanisms are maintained to help the fungus combat these repetitive elements. One of these defense mechanisms is called meiotic silencing by unpaired DNA (MSUD, which identifies and silences unpaired genes during meiosis. Utilizing common RNA interference (RNAi proteins, such as Dicer and Argonaute, MSUD targets mRNAs homologous to the unpaired sequence to achieve silencing. In this study, we have identified an additional silencing component, namely the cap-binding complex (CBC. Made up of cap-binding proteins CBP20 and CBP80, CBC associates with the 5′ cap of mRNA transcripts in eukaryotes. The loss of CBC leads to a deficiency in MSUD activity, suggesting its role in mediating silencing. As confirmed in this study, CBC is predominantly nuclear, although it is known to travel in and out of the nucleus to facilitate RNA transport. As seen in animals but not in plants, CBP20’s robust nuclear import depends on CBP80 in Neurospora. CBC interacts with a component (Argonaute of the perinuclear meiotic silencing complex (MSC, directly linking the two cellular factors.

  1. Post-transcriptional silencing of flavonol synthase mRNA in tobacco leads to fruits with arrested seed set.

    Directory of Open Access Journals (Sweden)

    Monika Mahajan

    Full Text Available Flavonoids are synthesized by phenylpropanoid pathway. They are known to participate in large number of physiological and biochemical processes in plants. Parthenocarpy and male sterility has earlier been reported by silencing chalcone synthase (CHS encoding gene. Silencing of CHS has blocked the synthesis of most of useful flavonoids including flavan-3-ols and flavonols. Also, these studies could not identify whether parthenocarpy/male sterility were due to lack of flavan-3-ols or flavonols or both. Flavonol synthase (FLS is an important enzyme of flavonoid pathway that catalyzes the formation of flavonols. In this article, we propose a novel strategy towards the generation of seedless or less-seeded fruits by downregulation of flavonol biosynthesis in tobacco (Nicotiana tabacum cv Xanthi through post-transcriptional gene silencing (PTGS of FLS encoding mRNA. The FLS silenced lines were observed for 20-80% reduction in FLS encoding gene expression and 25-93% reduction in flavonol (quercetin content. Interestingly, these FLS silenced tobacco lines also showed reduction in their anthocyanidins content. While the content of flavan-3-ols (catechin, epi-catechin and epi-gallocatechin was found to be increased in FLS silenced lines. The delayed flowering in FLS silenced lines could be due to decrease in level of indole acetic acid (IAA at apical region of their shoots. Furthermore, the pollen germination was hampered and pollens were unable to produce functional pollen tube in FLS silenced tobacco lines. Pods of FLS silenced lines contained significantly less number of seeds. The in vitro and in vivo studies where 1 µM quercetin was supplied to germination media, documented the restoration of normal pollen germination and pollen tube growth. This finding identified the role of flavonols particularly quercetin in pollen germination as well as in the regulation of plant fertility. Results also suggest a novel approach towards generation of seedless

  2. Stand age characteristics and soil properties affect species composition of vascular plants in short rotation coppice plantations

    OpenAIRE

    Sarah Baum; Martin Weih; Andreas Bolte

    2012-01-01

    Woody biomass plantations on agricultural sites are an attractive source of biomass for bioenergy, but their effects on local biodiversity are unclear. This study’s objective was to evaluate the influences of light availability, plantation age, and soil properties on phytodiversity in short rotation coppice (SRC) plantations. Ground vegetation mapping, irradiance measurement (PAR), and surface soil analyses were conducted in 15 willow and poplar SRC plantations in Central Sweden a...

  3. SGS3 Cooperates with RDR6 in Triggering Geminivirus-Induced Gene Silencing and in Suppressing Geminivirus Infection in Nicotiana Benthamiana

    Directory of Open Access Journals (Sweden)

    Fangfang Li

    2017-09-01

    Full Text Available RNA silencing has an important role in defending against virus infection in plants. Plants with the deficiency of RNA silencing components often show enhanced susceptibility to viral infections. RNA-dependent RNA polymerase (RDRs mediated-antiviral defense has a pivotal role in resistance to many plant viruses. In RDR6-mediated defense against viral infection, a plant-specific RNA binding protein, Suppressor of Gene Silencing 3 (SGS3, was also found to fight against some viruses in Arabidopsis. In this study, we showed that SGS3 from Nicotiana benthamiana (NbSGS3 is required for sense-RNA induced post-transcriptional gene silencing (S-PTGS and initiating sense-RNA-triggered systemic silencing. Further, the deficiency of NbSGS3 inhibited geminivirus-induced endogenous gene silencing (GIEGS and promoted geminivirus infection. During TRV-mediated NbSGS3 or N. benthamiana RDR6 (NbRDR6 silencing process, we found that their expression can be effectively fine-tuned. Plants with the knock-down of both NbSGS3 and NbRDR6 almost totally blocked GIEGS, and were more susceptible to geminivirus infection. These data suggest that NbSGS3 cooperates with NbRDR6 against GIEGS and geminivirus infection in N. benthamiana, which provides valuable information for breeding geminivirus-resistant plants.

  4. Development of Agrobacterium-mediated virus-induced gene silencing and performance evaluation of four marker genes in Gossypium barbadense.

    Directory of Open Access Journals (Sweden)

    Jinhuan Pang

    Full Text Available Gossypiumbarbadense is a cultivated cotton species and possesses many desirable traits, including high fiber quality and resistance to pathogens, especially Verticilliumdahliae (a devastating pathogen of Gossypium hirsutum, the main cultivated species. These elite traits are difficult to be introduced into G. hirsutum through classical breeding methods. In addition, genetic transformation of G. barbadense has not been successfully performed. It is therefore important to develop methods for evaluating the function and molecular mechanism of genes in G. barbadense. In this study, we had successfully introduced a virus-induced gene silencing (VIGS system into three cultivars of G. barbadense by inserting marker genes into the tobacco rattle virus (TRV vector. After we optimized the VIGS conditions, including light intensity, photoperiod, seedling age and Agrobacterium strain, 100% of plants agroinfiltrated with the GaPDS silencing vector showed white colored leaves. Three other marker genes, GaCLA1, GaANS and GaANR, were employed to further test this VIGS system in G. barbadense. The transcript levels of the endogenous genes in the silenced plants were reduced by more than 99% compared to control plants; these plants presented phenotypic symptoms 2 weeks after inoculation. We introduced a fusing sequence fragment of GaPDS and GaANR gene silencing vectors into a single plant, which resulted in both photobleaching and brownish coloration. The extent of silencing in plants agroinfiltrated with fusing two-gene-silencing vector was consistent with plants harboring a single gene silencing vector. The development of this VIGS system should promote analysis of gene function in G. barbadense, and help to contribute desirable traits for breeding of G. barbadense and G. hirsutum.

  5. Transgene-induced gene silencing is not affected by a change in ploidy level.

    Directory of Open Access Journals (Sweden)

    Daniela Pignatta

    Full Text Available BACKGROUND: Whole genome duplication, which results in polyploidy, is a common feature of plant populations and a recurring event in the evolution of flowering plants. Polyploidy can result in changes to gene expression and epigenetic instability. Several epigenetic phenomena, occurring at the transcriptional or post-transcriptional level, have been documented in allopolyploids (polyploids derived from species hybrids of Arabidopsis thaliana, yet findings in autopolyploids (polyploids derived from the duplication of the genome of a single species are limited. Here, we tested the hypothesis that an increase in ploidy enhances transgene-induced post-transcriptional gene silencing using autopolyploids of A. thaliana. METHODOLOGY/PRINCIPAL FINDINGS: Diploid and tetraploid individuals of four independent homozygous transgenic lines of A. thaliana transformed with chalcone synthase (CHS inverted repeat (hairpin constructs were generated. For each line diploids and tetraploids were compared for efficiency in post-transcriptional silencing of the endogenous CHS gene. The four lines differed substantially in their silencing efficiency. Yet, diploid and tetraploid plants derived from these plants and containing therefore identical transgene insertions showed no difference in the efficiency silencing CHS as assayed by visual scoring, anthocyanin assays and quantification of CHS mRNA. CONCLUSIONS/SIGNIFICANCE: Our results in A. thaliana indicated that there is no effect of ploidy level on transgene-induced post-transcriptional gene silencing. Our findings that post-transcriptional mechanisms were equally effective in diploids and tetraploids supports the use of transgene-driven post-transcriptional gene silencing as a useful mechanism to modify gene expression in polyploid species.

  6. The gifts of silence and solitude.

    Science.gov (United States)

    Schmidt Bunkers, Sandra

    2008-01-01

    In this column the author describes the importance of finding silence and solitude amid the noise and technology present today in the teaching-learning academy. Three gifts of silence and solitude are identified: the gift of comforting aloneness, the gift of vision for new horizons, and the gift of a sense of freedom. A humanbecoming perspective is used to explore the implications of these gifts. This column introduces a column by Diana Vander Woude describing her teaching-learning experience in leadership focusing on silence and solitude.

  7. The 2b protein of Asparagus virus 2 functions as an RNA silencing suppressor against systemic silencing to prove functional synteny with related cucumoviruses.

    Science.gov (United States)

    Shimura, Hanako; Masuta, Chikara; Yoshida, Naoto; Sueda, Kae; Suzuki, Masahiko

    2013-08-01

    Asparagus virus 2 (AV-2) is a member of the genus Ilarvirus in the family Bromoviridae. We cloned the coat protein (CP) and the 2b protein (2b) genes of AV-2 isolates from asparagus plants from various regions and found that the sequence for CP and for 2b was highly conserved among the isolates, suggesting that AV-2 from around the world is almost identical. We then made an AV-2 infectious clone by simultaneous inoculation with in vitro transcripts of RNAs 1-3 of AV-2 and in vitro-synthesized CP, which is necessary for initial infection. Because 2b of cucumoviruses in Bromoviridae can suppress systemic silencing as well as local silencing, we analyzed whether there is functional synteny of 2b between AV-2 and cucumovirus. Using the AV-2 infectious clone, we here provided first evidence that Ilarvirus 2b functions as an RNA silencing suppressor; AV-2 2b has suppressor activity against systemic silencing but not local silencing.

  8. AC2 and AC4 proteins of Tomato yellow leaf curl China virus and Tobacco curly shoot virus mediate suppression of RNA silencing

    Institute of Scientific and Technical Information of China (English)

    CUI Xiaofeng; ZHOU Xueping

    2004-01-01

    Tomato yellow leaf curl China virus Y10 isolate (TYLCCNV-Y10) alone could systemically infect host plants such as Nicotiana benthamiana without symptoms. In contrast, Tobacco curly shoot virus Y35 isolate (TbCSV-Y35) alone induces leaf curl symptoms in N. benthamiana. When inoculated into transgenic N. benthamiana plants expressing GFP gene (line 16c), TYLCCNV-Y10 neither reverses the established GFP silencing nor blocks the onset of GFP silencing. In contrast, TbCSV-Y35 can partially reverse the established GFP silencing and block the onset of GFP silencing in new leaves. In the patch co-infiltration assays, the AC2 and AC4 proteins of TYLCCNV-Y10 and TbCSV-Y35 could suppress local GFP silencing and delay systemic GFP silencing, suggesting that they are suppressors of RNA silencing. Comparison of the accumulation levels of GFP mRNA in the co-infiltration patches showed that Y10 AC2 and Y35 AC2 proteins had similar efficiency for suppression of RNA silencing. However, Y35 AC4 protein functioned as a stronger suppressor of RNA silencing than Y10 AC4 protein. Therefore, the pathogenicity difference between TbCSV-Y35 and TYLCCNV-Y10 may be related to the functional difference in their AC4 proteins.

  9. Dominance hierarchies, diversity and species richness of vascular plants in an alpine meadow: contrasting short and medium term responses to simulated global change

    Directory of Open Access Journals (Sweden)

    Juha M. Alatalo

    2014-05-01

    Full Text Available We studied the impact of simulated global change on a high alpine meadow plant community. Specifically, we examined whether short-term (5 years responses are good predictors for medium-term (7 years changes in the system by applying a factorial warming and nutrient manipulation to 20 plots in Latnjajaure, subarctic Sweden. Seven years of experimental warming and nutrient enhancement caused dramatic shifts in dominance hierarchies in response to the nutrient and the combined warming and nutrient enhancement treatments. Dominance hierarchies in the meadow moved from a community being dominated by cushion plants, deciduous, and evergreen shrubs to a community being dominated by grasses, sedges, and forbs. Short-term responses were shown to be inconsistent in their ability to predict medium-term responses for most functional groups, however, grasses showed a consistent and very substantial increase in response to nutrient addition over the seven years. The non-linear responses over time point out the importance of longer-term studies with repeated measurements to be able to better predict future changes. Forecasted changes to temperature and nutrient availability have implications for trophic interactions, and may ultimately influence the access to and palatability of the forage for grazers. Depending on what anthropogenic change will be most pronounced in the future (increase in nutrient deposits, warming, or a combination of them both, different shifts in community dominance hierarchies may occur. Generally, this study supports the productivity–diversity relationship found across arctic habitats, with community diversity peaking in mid-productivity systems and degrading as nutrient availability increases further. This is likely due the increasing competition in plant–plant interactions and the shifting dominance structure with grasses taking over the experimental plots, suggesting that global change could have high costs to biodiversity in the

  10. The Ebola virus VP35 protein is a suppressor of RNA silencing

    NARCIS (Netherlands)

    Haasnoot, J.; Vries, de W.; Geutjes, E.J.; Prins, M.W.; Haan, de P.; Berkhout, B.

    2007-01-01

    RNA silencing or interference (RNAi) is a gene regulation mechanism in eukaryotes that controls cell differentiation and developmental processes via expression of microRNAs. RNAi also serves as an innate antiviral defence response in plants, nematodes, and insects. This antiviral response is trigger

  11. Diverging affinity of tospovirus RNA silencing suppressor proteins, NSs, for various RNA duplex molecules

    NARCIS (Netherlands)

    Schnettler, E.; Hemmes, J.C.; Huisman, R.; Goldbach, R.W.; Prins, M.W.; Kormelink, R.J.M.

    2010-01-01

    The tospovirus NSs protein was previously shown to suppress the antiviral RNA silencing mechanism in plants. Here the biochemical analysis of NSs proteins from different tospoviruses, using purified NSs or NSs containing cell extracts, is described. The results showed that all tospoviral NSs

  12. Phenotypic changes associated with RNA interference silencing of chalcone synthase in apple (Malus × domestica).

    Science.gov (United States)

    Dare, Andrew P; Tomes, Sumathi; Jones, Midori; McGhie, Tony K; Stevenson, David E; Johnson, Ross A; Greenwood, David R; Hellens, Roger P

    2013-05-01

    We have identified in apple (Malus × domestica) three chalcone synthase (CHS) genes. In order to understand the functional redundancy of this gene family RNA interference knockout lines were generated where all three of these genes were down-regulated. These lines had no detectable anthocyanins and radically reduced concentrations of dihydrochalcones and flavonoids. Surprisingly, down-regulation of CHS also led to major changes in plant development, resulting in plants with shortened internode lengths, smaller leaves and a greatly reduced growth rate. Microscopic analysis revealed that these phenotypic changes extended down to the cellular level, with CHS-silenced lines showing aberrant cellular organisation in the leaves. Fruit collected from one CHS-silenced line was smaller than the 'Royal Gala' controls, lacked flavonoids in the skin and flesh and also had changes in cell morphology. Auxin transport experiments showed increased rates of auxin transport in a CHS-silenced line compared with the 'Royal Gala' control. As flavonoids are well known to be key modulators of auxin transport, we hypothesise that the removal of almost all flavonoids from the plant by CHS silencing creates a vastly altered environment for auxin transport to occur and results in the observed changes in growth and development. © 2013 The Authors The Plant Journal © 2013 Blackwell Publishing Ltd.

  13. The Ebola virus VP35 protein is a suppressor of RNA silencing

    NARCIS (Netherlands)

    Haasnoot, J.; Vries, de W.; Geutjes, E.J.; Prins, M.W.; Haan, de P.; Berkhout, B.

    2007-01-01

    RNA silencing or interference (RNAi) is a gene regulation mechanism in eukaryotes that controls cell differentiation and developmental processes via expression of microRNAs. RNAi also serves as an innate antiviral defence response in plants, nematodes, and insects. This antiviral response is trigger

  14. Baculovirus-mediated gene silencing in insect cells using intracellularly produced long double-stranded RNA

    NARCIS (Netherlands)

    Huang, Yi; Deng, F.; Hu, Z.H.; Vlak, J.M.; Wang, H.

    2007-01-01

    Double-stranded RNA-mediated interference (RNAi) has recently emerged as a powerful reverse genetics tool to silence gene expression in multiple organisms, including plants, nematodes and insects. In this study, DNA vectors capable of promoting the synthesis of long hairpin dsRNAs in vivo from a DNA

  15. Diverging affinity of tospovirus RNA silencing suppressor proteins, NSs, for various RNA duplex molecules

    NARCIS (Netherlands)

    Schnettler, E.; Hemmes, J.C.; Huisman, R.; Goldbach, R.W.; Prins, M.W.; Kormelink, R.J.M.

    2010-01-01

    The tospovirus NSs protein was previously shown to suppress the antiviral RNA silencing mechanism in plants. Here the biochemical analysis of NSs proteins from different tospoviruses, using purified NSs or NSs containing cell extracts, is described. The results showed that all tospoviral NSs protein

  16. The Ebola virus VP35 protein is a suppressor of RNA silencing

    NARCIS (Netherlands)

    Haasnoot, J.; Vries, de W.; Geutjes, E.J.; Prins, M.W.; Haan, de P.; Berkhout, B.

    2007-01-01

    RNA silencing or interference (RNAi) is a gene regulation mechanism in eukaryotes that controls cell differentiation and developmental processes via expression of microRNAs. RNAi also serves as an innate antiviral defence response in plants, nematodes, and insects. This antiviral response is

  17. TMV induces RNA decay pathways to modulate gene silencing and disease symptoms.

    Science.gov (United States)

    Conti, Gabriela; Zavallo, Diego; Venturuzzi, Andrea L; Rodriguez, Maria C; Crespi, Martin; Asurmendi, Sebastian

    2017-01-01

    RNA decay pathways comprise a combination of RNA degradation mechanisms that are implicated in gene expression, development and defense responses in eukaryotes. These mechanisms are known as the RNA Quality Control or RQC pathways. In plants, another important RNA degradation mechanism is the post-transcriptional gene silencing (PTGS) mediated by small RNAs (siRNAs). Notably, the RQC pathway antagonizes PTGS by preventing the entry of dysfunctional mRNAs into the silencing pathway to avoid global degradation of mRNA by siRNAs. Viral transcripts must evade RNA degrading mechanisms, thus viruses encode PTGS suppressor proteins to counteract viral RNA silencing. Here, we demonstrate that tobacco plants infected with TMV and transgenic lines expressing TMV MP and CP (coat protein) proteins (which are not linked to the suppression of silencing) display increased transcriptional levels of RNA decay genes. These plants also showed accumulation of cytoplasmic RNA granules with altered structure, increased rates of RNA decay for transgenes and defective transgene PTGS amplification. Furthermore, knockdown of RRP41 or RRP43 RNA exosome components led to lower levels of TMV accumulation with milder symptoms after infection, several developmental defects and miRNA deregulation. Thus, we propose that TMV proteins induce RNA decay pathways (in particular exosome components) to impair antiviral PTGS and this defensive mechanism would constitute an additional counter-defense strategy that lead to disease symptoms. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

  18. Asymptotic silence in loop quantum cosmology

    CERN Document Server

    Mielczarek, Jakub

    2012-01-01

    The state of asymptotic silence, characterized by causal disconnection of the space points, emerges from various approaches aiming to describe gravitational phenomena in the limit of large curvatures. In particular, such behavior was anticipated by Belinsky, Khalatnikov and Lifshitz (BKL) in their famous conjecture put forward in the early seventies of the last century. While the BKL conjecture is based on purely classical considerations, one can expect that asymptotic silence should have its quantum counterpart at the level of a more fundamental theory of quantum gravity, which is the relevant description of gravitational phenomena in the limit of large energy densities. Here, we summarize some recent results which give support to such a possibility. More precisely, we discuss occurrence of the asymptotic silence due to polymerization of space at the Planck scale, in the framework of loop quantum cosmology. In the discussed model, the state of asymptotic silence is realized at the energy density $\\rho = \\rho...

  19. Small RNA-Mediated Epigenetic Myostatin Silencing

    Directory of Open Access Journals (Sweden)

    Thomas C Roberts

    2012-01-01

    Full Text Available Myostatin (Mstn is a secreted growth factor that negatively regulates muscle mass and is therefore a potential pharmacological target for the treatment of muscle wasting disorders such as Duchenne muscular dystrophy. Here we describe a novel Mstn blockade approach in which small interfering RNAs (siRNAs complementary to a promoter-associated transcript induce transcriptional gene silencing (TGS in two differentiated mouse muscle cell lines. Silencing is sensitive to treatment with the histone deacetylase inhibitor trichostatin A, and the silent state chromatin mark H3K9me2 is enriched at the Mstn promoter following siRNA transfection, suggesting epigenetic remodeling underlies the silencing effect. These observations suggest that long-term epigenetic silencing may be feasible for Mstn and that TGS is a promising novel therapeutic strategy for the treatment of muscle wasting disorders.

  20. Public privacy: Reciprocity and Silence

    Directory of Open Access Journals (Sweden)

    Jenny Kennedy

    2014-10-01

    Full Text Available In his 1958 poem 'Dedication to my Wife' TS Eliot proclaims "these are private words addressed to you in public". Simultaneously written for his wife, Valerie Fletcher, and to the implied you of a discourse network, Eliot's poem helps to illustrate the narrative voices and silences that are constitutive of an intimate public sphere. This paper situates reciprocity as a condition of possibility for public privacy. It shows how reciprocity is enabled by systems of code operating through material and symbolic registers. Code promises to control communication, to produce neutral, systemic forms of meaning. Yet such automation is challenged by uneven and fragmented patterns of reciprocity. Moreover, examining the media of public privacy reveals historical trajectories important for understanding contemporary socio­technical platforms of reciprocity. To explore the implicit requirement of reciprocity in publicly private practices, three sites of communication are investigated framed by a media archaeology perspective: postal networks, the mail­art project PostSecret and the anonymous zine 'You'.

  1. Short Communication An efficient method for simultaneous extraction of high-quality RNA and DNA from various plant tissues.

    Science.gov (United States)

    Oliveira, R R; Viana, A J C; Reátegui, A C E; Vincentz, M G A

    2015-12-29

    Determination of gene expression is an important tool to study biological processes and relies on the quality of the extracted RNA. Changes in gene expression profiles may be directly related to mutations in regulatory DNA sequences or alterations in DNA cytosine methylation, which is an epigenetic mark. Correlation of gene expression with DNA sequence or epigenetic mark polymorphism is often desirable; for this, a robust protocol to isolate high-quality RNA and DNA simultaneously from the same sample is required. Although commercial kits and protocols are available, they are mainly optimized for animal tissues and, in general, restricted to RNA or DNA extraction, not both. In the present study, we describe an efficient and accessible method to extract both RNA and DNA simultaneously from the same sample of various plant tissues, using small amounts of starting material. The protocol was efficient in the extraction of high-quality nucleic acids from several Arabidopsis thaliana tissues (e.g., leaf, inflorescence stem, flower, fruit, cotyledon, seedlings, root, and embryo) and from other tissues of non-model plants, such as Avicennia schaueriana (Acanthaceae), Theobroma cacao (Malvaceae), Paspalum notatum (Poaceae), and Sorghum bicolor (Poaceae). The obtained nucleic acids were used as templates for downstream analyses, such as mRNA sequencing, quantitative real time-polymerase chain reaction, bisulfite treatment, and others; the results were comparable to those obtained with commercial kits. We believe that this protocol could be applied to a broad range of plant species, help avoid technical and sampling biases, and facilitate several RNA- and DNA-dependent analyses.

  2. Does SO{sub 2} fumigation change the chemical defense of woody plants: the effect of short-term SO{sub 2} fumigation on the metabolism of deciduous Salix Myrsinifolia plants

    Energy Technology Data Exchange (ETDEWEB)

    Julkunen-Tiitto, R.; Lavola, A.; Kainulainen, P. [University of Joensuu, Joensuu (Finland). Dept. of Biology

    1995-08-01

    The effect of a moderate increase in atmospheric sulfur dioxide on the production of phenolic secondary chemicals, soluble sugars and phytomass distribution within plants was investigated in six willow ({ital Salix myrsinifolia Salisb}) clones. The plants were cultivated for 3 weeks under 0.11 ppm of SO{sub 2} (300{mu}g m{sup -3}). The production of salicin and chlorogenic acid was significantly reduced under increased SO{sub 2}. However, salicortin, 2{prime}-O-acetylsalicortin, (+)-catechin and two unknown phenolics did not show any clear trend. The increase in SO{sub 2} did not affect the glucose, fructose and sucrose contents. The final weight of the SO{sub 2}-treatment plants was significantly greater than that of the control plants: the leaf, stem and root phytomass was from 14 to 48% greater under increased SO{sub 2}. All the clones showed the same trend, although there was a significant variation in phytomass production. Results indicate, although not consistently, that even a short-term exposure of enhanced atmospheric SO{sub 2} may change moderately the accumulation pattern of willow phenolics. 20 refs., 2 tabs.

  3. An intronic microRNA silences genes that are functionally antagonistic to its host gene

    OpenAIRE

    Barik, Sailen

    2008-01-01

    MicroRNAs (miRNAs) are short noncoding RNAs that down-regulate gene expression by silencing specific target mRNAs. While many miRNAs are transcribed from their own genes, nearly half map within introns of ‘host’ genes, the significance of which remains unclear. We report that transcriptional activation of apoptosis-associated tyrosine kinase (AATK), essential for neuronal differentiation, also generates miR-338 from an AATK gene intron that silences a family of mRNAs whose protein products ar...

  4. Suppression of RNA Silencing by a Geminivirus Nuclear Protein, AC2, Correlates with Transactivation of Host Genes†

    Science.gov (United States)

    Trinks, Daniela; Rajeswaran, R.; Shivaprasad, P. V.; Akbergenov, Rashid; Oakeley, Edward J.; Veluthambi, K.; Hohn, Thomas; Pooggin, Mikhail M.

    2005-01-01

    Bipartite geminiviruses encode a small protein, AC2, that functions as a transactivator of viral transcription and a suppressor of RNA silencing. A relationship between these two functions had not been investigated before. We characterized both of these functions for AC2 from Mungbean yellow mosaic virus-Vigna (MYMV). When transiently expressed in plant protoplasts, MYMV AC2 strongly transactivated the viral promoter; AC2 was detected in the nucleus, and a split nuclear localization signal (NLS) was mapped. In a model Nicotiana benthamiana plant, in which silencing can be triggered biolistically, AC2 reduced local silencing and prevented its systemic spread. Mutations in the AC2 NLS or Zn finger or deletion of its activator domain abolished both these effects, suggesting that suppression of silencing by AC2 requires transactivation of host suppressor(s). In line with this, in Arabidopsis protoplasts, MYMV AC2 or its homologue from African cassava mosaic geminivirus coactivated >30 components of the plant transcriptome, as detected with Affymetrix ATH1 GeneChips. Several corresponding promoters cloned from Arabidopsis were strongly induced by both AC2 proteins. These results suggest that silencing suppression and transcription activation by AC2 are functionally connected and that some of the AC2-inducible host genes discovered here may code for components of an endogenous network that controls silencing. PMID:15681452

  5. Suppression of RNA silencing by a geminivirus nuclear protein, AC2, correlates with transactivation of host genes.

    Science.gov (United States)

    Trinks, Daniela; Rajeswaran, R; Shivaprasad, P V; Akbergenov, Rashid; Oakeley, Edward J; Veluthambi, K; Hohn, Thomas; Pooggin, Mikhail M

    2005-02-01

    Bipartite geminiviruses encode a small protein, AC2, that functions as a transactivator of viral transcription and a suppressor of RNA silencing. A relationship between these two functions had not been investigated before. We characterized both of these functions for AC2 from Mungbean yellow mosaic virus-Vigna (MYMV). When transiently expressed in plant protoplasts, MYMV AC2 strongly transactivated the viral promoter; AC2 was detected in the nucleus, and a split nuclear localization signal (NLS) was mapped. In a model Nicotiana benthamiana plant, in which silencing can be triggered biolistically, AC2 reduced local silencing and prevented its systemic spread. Mutations in the AC2 NLS or Zn finger or deletion of its activator domain abolished both these effects, suggesting that suppression of silencing by AC2 requires transactivation of host suppressor(s). In line with this, in Arabidopsis protoplasts, MYMV AC2 or its homologue from African cassava mosaic geminivirus coactivated >30 components of the plant transcriptome, as detected with Affymetrix ATH1 GeneChips. Several corresponding promoters cloned from Arabidopsis were strongly induced by both AC2 proteins. These results suggest that silencing suppression and transcription activation by AC2 are functionally connected and that some of the AC2-inducible host genes discovered here may code for components of an endogenous network that controls silencing.

  6. The development of an efficient multipurpose bean pod mottle virus viral vector set for foreign gene expression and RNA silencing.

    Science.gov (United States)

    Zhang, Chunquan; Bradshaw, Jeffrey D; Whitham, Steven A; Hill, John H

    2010-05-01

    Plant viral vectors are valuable tools for heterologous gene expression, and because of virus-induced gene silencing (VIGS), they also have important applications as reverse genetics tools for gene function studies. Viral vectors are especially useful for plants such as soybean (Glycine max) that are recalcitrant to transformation. Previously, two generations of bean pod mottle virus (BPMV; genus Comovirus) vectors have been developed for overexpressing and silencing genes in soybean. However, the design of the previous vectors imposes constraints that limit their utility. For example, VIGS target sequences must be expressed as fusion proteins in the same reading frame as the viral polyprotein. This requirement limits the design of VIGS target sequences to open reading frames. Furthermore, expression of multiple genes or simultaneous silencing of one gene and expression of another was not possible. To overcome these and other issues, a new BPMV-based vector system was developed to facilitate a variety of applications for gene function studies in soybean as well as in common bean (Phaseolus vulgaris). These vectors are designed for simultaneous expression of multiple foreign genes, insertion of noncoding/antisense sequences, and simultaneous expression and silencing. The simultaneous expression of green fluorescent protein and silencing of phytoene desaturase shows that marker gene-assisted silencing is feasible. These results demonstrate the utility of this BPMV vector set for a wide range of applications in soybean and common bean, and they have implications for improvement of other plant virus-based vector systems.

  7. Control Strategies to Smooth Short-Term Power Fluctuations in Large Photovoltaic Plants Using Battery Storage Systems

    Directory of Open Access Journals (Sweden)

    Javier Marcos

    2014-10-01

    Full Text Available The variations in irradiance produced by changes in cloud cover can cause rapid fluctuations in the power generated by large photovoltaic (PV plants. As the PV power share in the grid increases, such fluctuations may adversely affect power quality and reliability. Thus, energy storage systems (ESS are necessary in order to smooth power fluctuations below the maximum allowable. This article first proposes a new control strategy (step-control, to improve the results in relation to two state-of-the-art strategies, ramp-rate control and moving average. It also presents a method to quantify the storage capacity requirements according to the three different smoothing strategies and for different PV plant sizes. Finally, simulations shows that, although the moving-average (MA strategy requires the smallest capacity, it presents more losses (2–3 times more and produces a much higher number of cycles over the ESS (around 10 times more, making it unsuitable with storage technologies as lithium-ion. The step-control shown as a better option in scenery with exigent ramp restrictions (around 2%/min and distributed generation against the ramp-rate control in all ESS key aspects: 20% less of capacity, up to 30% less of losses and a 40% less of ageing. All the simulations were based on real PV production data, taken every 5 s in the course of one year (2012 from a number of systems with power outputs ranging from 550 kW to 40 MW.

  8. Potential benefits of commercial willow Short Rotation Coppice (SRC) for farm-scale plant and invertebrate communities in the agri-environment

    Energy Technology Data Exchange (ETDEWEB)

    Rowe, Rebecca L.; Hanley, Mick E.; Goulson, Dave; Clarke, Donna J.; Doncaster, C. Patrick; Taylor, Gail [University of Southampton, Faculty of Natural and Environmental Sciences, Life Sciences Building, Southampton, S017 1BJ (United Kingdom)

    2011-01-15

    The cultivation of bioenergy crops (BECs) represents a significant land-use change in agri-environments, but their deployment has raised important issues globally regarding possible impacts on biodiversity. Few studies however, have systematically examined the effect of commercial scale bioenergy plantations on biodiversity in agri-ecosystems. In this study we investigate how the abundance and diversity of two key components of farmland biodiversity (ground flora and winged invertebrates) varied between mature willow Short Rotation Coppice (SRC) and two alternative land-use options (arable crops and set-aside land). Although the abundance of winged invertebrates was similar across all land-uses, taxonomic composition varied markedly. Hymenoptera and large Hemiptera (>5 mm) were more abundant in willow SRC than in arable or set-aside. Similarly although plant species richness was greater in set-aside, our data show that willow SRC supports a different plant community to the other land-uses, being dominated by competitive perennial species such as Elytrigia repens and Urtica dioica. Our results suggest that under current management practices a mixed farming system incorporating willow SRC can benefit native farm-scale biodiversity. In particular the reduced disturbance in willow SRC allows the persistence of perennial plant species, potentially providing a stable refuge and food sources for invertebrates. In addition, increased Hymenoptera abundance in willow SRC could potentially have concomitant effects on ecosystem processes, as many members of this Order are important pollinators of crop plants or otherwise fulfil an important beneficial role as predators or parasites of crop pests. (author)

  9. ABCE1 is a highly conserved RNA silencing suppressor.

    Directory of Open Access Journals (Sweden)

    Kairi Kärblane

    Full Text Available ATP-binding cassette sub-family E member 1 (ABCE1 is a highly conserved protein among eukaryotes and archaea. Recent studies have identified ABCE1 as a ribosome-recycling factor important for translation termination in mammalian cells, yeast and also archaea. Here we report another conserved function of ABCE1. We have previously described AtRLI2, the homolog of ABCE1 in the plant Arabidopsis thaliana, as an endogenous suppressor of RNA silencing. In this study we show that this function is conserved: human ABCE1 is able to suppress RNA silencing in Nicotiana benthamiana plants, in mammalian HEK293 cells and in the worm Caenorhabditis elegans. Using co-immunoprecipitation and mass spectrometry, we found a number of potential ABCE1-interacting proteins that might support its function as an endogenous suppressor of RNA interference. The interactor candidates are associated with epigenetic regulation, transcription, RNA processing and mRNA surveillance. In addition, one of the identified proteins is translin, which together with its binding partner TRAX supports RNA interference.

  10. Efficient Virus-Induced Gene Silencing in Solanum rostratum.

    Directory of Open Access Journals (Sweden)

    Lan-Huan Meng

    Full Text Available Solanum rostratum is a "super weed" that grows fast, is widespread, and produces the toxin solanine, which is harmful to both humans and other animals. To our knowledge, no study has focused on its molecular biology owing to the lack of available transgenic methods and sequence information for S. rostratum. Virus-induced gene silencing (VIGS is a powerful tool for the study of gene function in plants; therefore, in the present study, we aimed to establish tobacco rattle virus (TRV-derived VIGS in S. rostratum. The genes for phytoene desaturase (PDS and Chlorophyll H subunit (ChlH of magnesium protoporphyrin chelatase were cloned from S. rostratum and used as reporters of gene silencing. It was shown that high-efficiency VIGS can be achieved in the leaves, flowers, and fruit of S. rostratum. Moreover, based on our comparison of three different types of infection methods, true leaf infection was found to be more efficient than cotyledon and sprout infiltration in long-term VIGS in multiple plant organs. In conclusion, the VIGS technology and tomato genomic sequences can be used in the future to study gene function in S. rostratum.

  11. Efficient Virus-Induced Gene Silencing in Solanum rostratum

    Science.gov (United States)

    Meng, Lan-Huan; Wang, Rui-Heng; Zhu, Ben-Zhong; Zhu, Hong-Liang; Luo, Yun-Bo; Fu, Da-Qi

    2016-01-01

    Solanum rostratum is a “super weed” that grows fast, is widespread, and produces the toxin solanine, which is harmful to both humans and other animals. To our knowledge, no study has focused on its molecular biology owing to the lack of available transgenic methods and sequence information for S. rostratum. Virus-induced gene silencing (VIGS) is a powerful tool for the study of gene function in plants; therefore, in the present study, we aimed to establish tobacco rattle virus (TRV)-derived VIGS in S. rostratum. The genes for phytoene desaturase (PDS) and Chlorophyll H subunit (ChlH) of magnesium protoporphyrin chelatase were cloned from S. rostratum and used as reporters of gene silencing. It was shown that high-efficiency VIGS can be achieved in the leaves, flowers, and fruit of S. rostratum. Moreover, based on our comparison of three different types of infection methods, true leaf infection was found to be more efficient than cotyledon and sprout infiltration in long-term VIGS in multiple plant organs. In conclusion, the VIGS technology and tomato genomic sequences can be used in the future to study gene function in S. rostratum. PMID:27258320

  12. Efficient Virus-Induced Gene Silencing in Solanum rostratum.

    Science.gov (United States)

    Meng, Lan-Huan; Wang, Rui-Heng; Zhu, Ben-Zhong; Zhu, Hong-Liang; Luo, Yun-Bo; Fu, Da-Qi

    2016-01-01

    Solanum rostratum is a "super weed" that grows fast, is widespread, and produces the toxin solanine, which is harmful to both humans and other animals. To our knowledge, no study has focused on its molecular biology owing to the lack of available transgenic methods and sequence information for S. rostratum. Virus-induced gene silencing (VIGS) is a powerful tool for the study of gene function in plants; therefore, in the present study, we aimed to establish tobacco rattle virus (TRV)-derived VIGS in S. rostratum. The genes for phytoene desaturase (PDS) and Chlorophyll H subunit (ChlH) of magnesium protoporphyrin chelatase were cloned from S. rostratum and used as reporters of gene silencing. It was shown that high-efficiency VIGS can be achieved in the leaves, flowers, and fruit of S. rostratum. Moreover, based on our comparison of three different types of infection methods, true leaf infection was found to be more efficient than cotyledon and sprout infiltration in long-term VIGS in multiple plant organs. In conclusion, the VIGS technology and tomato genomic sequences can be used in the future to study gene function in S. rostratum.

  13. Virus-induced gene silencing and transient gene expression in soybean using Bean pod mottle virus infectious clones

    Science.gov (United States)

    Virus-induced gene silencing (VIGS) is a powerful and rapid approach for determining the functions of plant genes. The basis of VIGS is that a viral genome is engineered so that it can carry fragments of plant genes, typically in the 200-300 base pair size range. The recombinant viruses are used to ...

  14. Development of Virus-Induced Gene Expression and Silencing Vector Derived from Grapevine Algerian Latent Virus

    OpenAIRE

    Sang-Ho Park; Hoseong Choi; Semin Kim; Won Kyong Cho; Kook-Hyung Kim

    2016-01-01

    Grapevine Algerian latent virus (GALV) is a member of the genus Tombusvirus in the Tombusviridae and infects not only woody perennial grapevine plant but also herbaceous Nicotiana benthamiana plant. In this study, we developed GALV-based gene expression and virus-induced gene silencing (VIGS) vectors in N. benthamiana. The GALV coat protein deletion vector, pGMG, was applied to express the reporter gene, green fluorescence protein (GFP), but the expression of GFP was not detected due to the n...

  15. Short-term emergency response planning and risk assessment via an integrated modeling system for nuclear power plants in complex terrain

    Institute of Scientific and Technical Information of China (English)

    Ni-Bin CHANG; Yu-Chi WENG

    2013-01-01

    Short-term predictions of potential impacts from accidental release of various radionuclides at nuclear power plants are acutely needed,especially after the Fukushima accident in Japan.An integrated modeling system that provides expert services to assess the consequences of accidental or intentional releases of radioactive materials to the atmosphere has received wide attention.These scenarios can be initiated either by accident due to human,software,or mechanical failures,or from intentional acts such as sabotage and radiological dispersal devices.Stringent action might be required just minutes after the occurrence of accidental or intentional release.To fulfill the basic functions of emergency preparedness and response systems,previous studies seldom consider the suitability of air pollutant dispersion models or the connectivity between source term,dispersion,and exposure assessment models in a holistic context for decision support.Therefore,the Gaussian plume and puff models,which are only suitable for illustrating neutral air pollutants in flat terrain conditional to limited meteorological situations,are frequently used to predict the impact from accidental release of industrial sources.In situations with complex terrain or special meteorological conditions,the proposing emergency response actions might be questionable and even intractable to decisionmakers responsible for maintaining public health and environmental quality.This study is a preliminary effort to integrate the source term,dispersion,and exposure assessment models into a Spatial Decision Support System (SDSS) to tackle the complex issues for short-term emergency response planning and risk assessment at nuclear power plants.Through a series model screening procedures,we found that the diagnostic (objective) wind field model with the aid of sufficient on-site meteorological monitoring data was the most applicable model to promptly address the trend of local wind field patterns.However,most of the

  16. Short-term emergency response planning and risk assessment via an integrated modeling system for nuclear power plants in complex terrain

    Science.gov (United States)

    Chang, Ni-Bin; Weng, Yu-Chi

    2013-03-01

    Short-term predictions of potential impacts from accidental release of various radionuclides at nuclear power plants are acutely needed, especially after the Fukushima accident in Japan. An integrated modeling system that provides expert services to assess the consequences of accidental or intentional releases of radioactive materials to the atmosphere has received wide attention. These scenarios can be initiated either by accident due to human, software, or mechanical failures, or from intentional acts such as sabotage and radiological dispersal devices. Stringent action might be required just minutes after the occurrence of accidental or intentional release. To fulfill the basic functions of emergency preparedness and response systems, previous studies seldom consider the suitability of air pollutant dispersion models or the connectivity between source term, dispersion, and exposure assessment models in a holistic context for decision support. Therefore, the Gaussian plume and puff models, which are only suitable for illustrating neutral air pollutants in flat terrain conditional to limited meteorological situations, are frequently used to predict the impact from accidental release of industrial sources. In situations with complex terrain or special meteorological conditions, the proposing emergency response actions might be questionable and even intractable to decisionmakers responsible for maintaining public health and environmental quality. This study is a preliminary effort to integrate the source term, dispersion, and exposure assessment models into a Spatial Decision Support System (SDSS) to tackle the complex issues for short-term emergency response planning and risk assessment at nuclear power plants. Through a series model screening procedures, we found that the diagnostic (objective) wind field model with the aid of sufficient on-site meteorological monitoring data was the most applicable model to promptly address the trend of local wind field patterns

  17. Exonuclease-mediated degradation of nascent RNA silences genes linked to severe malaria

    DEFF Research Database (Denmark)

    Zhang, Qingfeng; Siegel, T Nicolai; Martins, Rafael M

    2014-01-01

    malaria. The mechanism determining upsA activation remains unknown. Here we show that an entirely new type of gene silencing mechanism involving an exonuclease-mediated degradation of nascent RNA controls the silencing of genes linked to severe malaria. We identify a novel chromatin......-associated exoribonuclease, termed PfRNase II, that controls the silencing of upsA var genes by marking their transcription start site and intron-promoter regions leading to short-lived cryptic RNA. Parasites carrying a deficient PfRNase II gene produce full-length upsA var transcripts and intron-derived antisense long non......-coding RNA. The presence of stable upsA var transcripts overcomes monoallelic expression, resulting in the simultaneous expression of both upsA and upsC type PfEMP1 proteins on the surface of individual infected red blood cells. In addition, we observe an inverse relationship between transcript levels of Pf...

  18. Phytophthora have distinct endogenous small RNA populations that include short interfering and microRNAs.

    Directory of Open Access Journals (Sweden)

    Noah Fahlgren

    Full Text Available In eukaryotes, RNA silencing pathways utilize 20-30-nucleotide small RNAs to regulate gene expression, specify and maintain chromatin structure, and repress viruses and mobile genetic elements. RNA silencing was likely present in the common ancestor of modern eukaryotes, but most research has focused on plant and animal RNA silencing systems. Phytophthora species belong to a phylogenetically distinct group of economically important plant pathogens that cause billions of dollars in yield losses annually as well as ecologically devastating outbreaks. We analyzed the small RNA-generating components of the genomes of P. infestans, P. sojae and P. ramorum using bioinformatics, genetic, phylogenetic and high-throughput sequencing-based methods. Each species produces two distinct populations of small RNAs that are predominantly 21- or 25-nucleotides long. The 25-nucleotide small RNAs were primarily derived from loci encoding transposable elements and we propose that these small RNAs define a pathway of short-interfering RNAs that silence repetitive genetic elements. The 21-nucleotide small RNAs were primarily derived from inverted repeats, including a novel microRNA family that is conserved among the three species, and several gene families, including Crinkler effectors and type III fibronectins. The Phytophthora microRNA is predicted to target a family of amino acid/auxin permeases, and we propose that 21-nucleotide small RNAs function at the post-transcriptional level. The functional significance of microRNA-guided regulation of amino acid/auxin permeases and the association of 21-nucleotide small RNAs with Crinkler effectors remains unclear, but this work provides a framework for testing the role of small RNAs in Phytophthora biology and pathogenesis in future work.

  19. Phytophthora have distinct endogenous small RNA populations that include short interfering and microRNAs.

    Science.gov (United States)

    Fahlgren, Noah; Bollmann, Stephanie R; Kasschau, Kristin D; Cuperus, Josh T; Press, Caroline M; Sullivan, Christopher M; Chapman, Elisabeth J; Hoyer, J Steen; Gilbert, Kerrigan B; Grünwald, Niklaus J; Carrington, James C

    2013-01-01

    In eukaryotes, RNA silencing pathways utilize 20-30-nucleotide small RNAs to regulate gene expression, specify and maintain chromatin structure, and repress viruses and mobile genetic elements. RNA silencing was likely present in the common ancestor of modern eukaryotes, but most research has focused on plant and animal RNA silencing systems. Phytophthora species belong to a phylogenetically distinct group of economically important plant pathogens that cause billions of dollars in yield losses annually as well as ecologically devastating outbreaks. We analyzed the small RNA-generating components of the genomes of P. infestans, P. sojae and P. ramorum using bioinformatics, genetic, phylogenetic and high-throughput sequencing-based methods. Each species produces two distinct populations of small RNAs that are predominantly 21- or 25-nucleotides long. The 25-nucleotide small RNAs were primarily derived from loci encoding transposable elements and we propose that these small RNAs define a pathway of short-interfering RNAs that silence repetitive genetic elements. The 21-nucleotide small RNAs were primarily derived from inverted repeats, including a novel microRNA family that is conserved among the three species, and several gene families, including Crinkler effectors and type III fibronectins. The Phytophthora microRNA is predicted to target a family of amino acid/auxin permeases, and we propose that 21-nucleotide small RNAs function at the post-transcriptional level. The functional significance of microRNA-guided regulation of amino acid/auxin permeases and the association of 21-nucleotide small RNAs with Crinkler effectors remains unclear, but this work provides a framework for testing the role of small RNAs in Phytophthora biology and pathogenesis in future work.

  20. Effects of seven RNA silencing suppressors on heterologous expression of green fluorescence protein expression mediated by a plant virus-based system in Nicotiana benthamiana%7种RNA沉默抑制子对植物病毒载体表达系统表达水平的影响

    Institute of Scientific and Technical Information of China (English)

    王盛; 董洁; 曹慜; 穆红珍; 丁国平; 张虹

    2012-01-01

    Objective To test the effects of 7 virus-encoded RNA silencing suppressors (RSSs) for enhancement of a plant virus-based vector system-mediated heterologous expression of green fluorescence protein (GFP) in Nicotiana benthamiana. Methods Seven transient expression vectors for the 7 RSSs were constructed and co-inoculated on the leaves of Nicotiana benthamiana with PVXdt-GFP vector, a novel Potato virus X-based plant expression vector, through agroinfiltration. The protein and mRNA expression levels of the reporter gene GFP in the co-inoculated Nicotiana leaves were examined by Western blotting, ELISA and RT-qPCR to assess the effect of the RSSs for GFP expression enhancement. Results The 7 RSSs differed in the degree and duration of enhancement of heterologous GFP expression, and the pl9 protein of Tomato bushy stunt virus (TBSV) induced the highest expression of GFP. African cassava mosaic virus AC2 protein and Rice yellow mettle virus PI protein produced no obvious enhancement GFP expression. Conclusion Transient co-expression of RSSs suppresses host silencing response to allow high-level and long-term expression of heterologous genes in plant, but the optimal RSS has to be identified for each plant virus-based expression vector system.%目的 探索不同植物病毒RNA沉默抑制子对植物病毒载体表达系统重组蛋白表达水平的作用,为合理高效地利用这一新型的外源基因表达平台奠定基础.方法 构建了7种不同的RNA沉默抑制子瞬时表达载体,以农杆菌渗滤法,与马铃薯X病毒表达载体PVXdt-GFP共侵染寄主植物本明烟,通过对报告基因绿色荧光蛋白(GFP)的荧光观察,并以Western blotting、ELISA 和RT-qPCR等测定GFP在烟草中的表达情况,分析不同RNA沉默抑制子对植物中外源基因表达水平的作用和特点.结果 7种病毒RNA沉默抑制子对外源基因GFP在烟草中表达水平的作用效果和持续时间存在差异,其中,番茄丛矮病毒的P19蛋白的

  1. Regulation of polyphenols accumulation by combined overexpression/silencing key enzymes of phyenylpropanoid pathway

    Institute of Scientific and Technical Information of China (English)

    Junli Chang; Jie Luo; Guangyuan He

    2009-01-01

    There is a growing interest in the metabolic engineering of plant with increased desirable polyphenols such as chlorogenic acid (CGA) and rutin. In this study, the effects of overexpression of both phenylalanine ammonia lyase (AtPAL2), the first enzyme of the phe-nylpropanoid pathway, and hydroxycinnamoyl-CoA quinate:hydroxycinnamoyl transferase (NtHQT), the last enzyme of CGA biosynthesis, and the overexpres-sion of AtPAL2 together with silencing of NtHQT were investigated in tobacco. Transgenic tobacco plants over-expressing AtPAL2 showed two and five times increases of CGA and rutin levels than the wild-type (WT) plants, respectively. Overexpression of NtHQT further increases the accumulation of CGA in the AtPAL2 plants to about three times than that of the WT level, while silencing of NtHQT in AtPAL2 plants results in ~12 times increase in rutin level than that of the WT plants. Simultaneous overexpression of phenylalanine ammonia lyase (PAL) and overexpression/silencing HQT could be used for the production of functional food with increased polyphenols.

  2. Stable Short-Term Frequency Support Using Adaptive Gains for a DFIG-Based Wind Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jinsik; Jang, Gilsoo; Muljadi, Eduard; Blaabjerg, Frede; Chen, Zhe; Cheol Kang, Yong

    2016-09-01

    For the fixed-gain inertial control of wind power plants (WPPs), a large gain setting provides a large contribution to supporting system frequency control, but it may cause over-deceleration for a wind turbine generator that has a small amount of kinetic energy (KE). Further, if the wind speed decreases during inertial control, even a small gain may cause over-deceleration. This paper proposes a stable inertial control scheme using adaptive gains for a doubly fed induction generator (DFIG)-based WPP. The scheme aims to improve the frequency nadir (FN) while ensuring stable operation of all DFIGs, particularly when the wind speed decreases during inertial control. In this scheme, adaptive gains are set to be proportional to the KE stored in DFIGs, which is spatially and temporally dependent. To improve the FN, upon detecting an event, large gains are set to be proportional to the KE of DFIGs; to ensure stable operation, the gains decrease with the declining KE. The simulation results demonstrate that the scheme improves the FN while ensuring stable operation of all DFIGs in various wind and system conditions. Further, it prevents over-deceleration even when the wind speed decreases during inertial control.

  3. Calibration and validation of models for short-term decomposition and N mineralization of plant residues in the tropics

    Directory of Open Access Journals (Sweden)

    Alexandre Ferreira do Nascimento

    2012-12-01

    Full Text Available Insight of nutrient release patterns associated with the decomposition of plant residues is important for their effective use as a green manure in food production systems. Thus, this study aimed to evaluate the ability of the Century, APSIM and NDICEA simulation models for predicting the decomposition and N mineralization of crop residues in the tropical Atlantic forest biome, Brazil. The simulation models were calibrated based on actual decomposition and N mineralization rates of three types of crop residues with different chemical and biochemical composition. The models were also validated for different pedo-climatic conditions and crop residues conditions. In general, the accuracy of decomposition and N mineralization improved after calibration. Overall RMSE values for the decomposition and N mineralization of the crop materials varied from 7.4 to 64.6% before models calibration compared to 3.7 to 16.3 % after calibration. Therefore, adequate calibration of the models is indispensable for use them under humid tropical conditions. The NDICEA model generally outperformed the other models. However, the decomposition and N mineralization was not very accurate during the first 30 days of incubation, especially for easily decomposable crop residues. An additional model variable may be required to capture initial microbiological growth as affected by the moisture dynamics of the residues, as is the case in surface residues decomposition models.

  4. Inhibition of RNA silencing by the coat protein of Pelargonium flower break virus: distinctions from closely related suppressors.

    Science.gov (United States)

    Martínez-Turiño, Sandra; Hernández, Carmen

    2009-02-01

    Viral-derived double-stranded RNAs (dsRNAs) activate RNA silencing, generating small interfering RNAs (siRNAs) which are incorporated into an RNA-induced silencing complex (RISC) that promotes homology-dependent degradation of cognate RNAs. To counteract this, plant viruses express RNA silencing suppressors. Here, we show that the coat protein (CP) of Pelargonium flower break virus (PFBV), a member of the genus Carmovirus, is able to efficiently inhibit RNA silencing. Interestingly, PFBV CP blocked both sense RNA- and dsRNA-triggered RNA silencing and did not preclude generation of siRNAs, which is in contrast with the abilities that have been reported for other carmoviral CPs. We have also found that PFBV CP can bind siRNAs and that this ability correlates with silencing suppression activity and enhancement of potato virus X pathogenicity. Collectively, the results indicate that PFBV CP inhibits RNA silencing by sequestering siRNAs and preventing their incorporation into a RISC, thus behaving similarly to unrelated viral suppressors but dissimilarly to orthologous ones.

  5. Development of a gene silencing DNA vector derived from a broad host range geminivirus

    Directory of Open Access Journals (Sweden)

    Hancock Leandria C

    2009-07-01

    Full Text Available Abstract Background Gene silencing is proving to be a powerful tool for genetic, developmental, and physiological analyses. The use of viral induced gene silencing (VIGS offers advantages to transgenic approaches as it can be potentially applied to non-model systems for which transgenic techniques are not readily available. However, many VIGS vectors are derived from Gemini viruses that have limited host ranges. We present a new, unipartite vector that is derived from a curtovirus that has a broad host range and will be amenable to use in many non-model systems. Results The construction of a gene silencing vector derived from the geminivirus Beet curly top virus (BCTV, named pWSRi, is reported. Two versions of the vector have been developed to allow application by biolistic techniques or by agro-infiltration. We demonstrate its ability to silence nuclear genes including ribulose bisphosphate carboxylase small subunit (rbcS, transketolase, the sulfur allele of magnesium chelatase (ChlI, and two homeotic transcription factors in spinach or tomato by generating gene-specific knock-down phenotypes. Onset of phenotypes occurred 3 to 12 weeks post-inoculation, depending on the target gene, in organs that developed after the application. The vector lacks movement genes and we found no evidence for significant spread from the site of inoculation. However, viral amplification in inoculated tissue was detected and is necessary for systemic silencing, suggesting that signals generated from active viral replicons are efficiently transported within the plant. Conclusion The unique properties of the pWSRi vector, the ability to silence genes in meristem tissue, the separation of virus and silencing phenotypes, and the broad natural host range of BCTV, suggest that it will have wide utility.

  6. Polyphenoloxidase silencing affects latex coagulation in Taraxacum species.

    Science.gov (United States)

    Wahler, Daniela; Gronover, Christian Schulze; Richter, Carolin; Foucu, Florence; Twyman, Richard M; Moerschbacher, Bruno M; Fischer, Rainer; Muth, Jost; Prüfer, Dirk

    2009-09-01

    Latex is the milky sap that is found in many different plants. It is produced by specialized cells known as laticifers and can comprise a mixture of proteins, carbohydrates, oils, secondary metabolites, and rubber that may help to prevent herbivory and protect wound sites against infection. The wound-induced browning of latex suggests that it contains one or more phenol-oxidizing enzymes. Here, we present a comprehensive analysis of the major latex proteins from two dandelion species, Taraxacum officinale and Taraxacum kok-saghyz, and enzymatic studies showing that polyphenoloxidase (PPO) is responsible for latex browning. Electrophoretic analysis and amino-terminal sequencing of the most abundant proteins in the aqueous latex fraction revealed the presence of three PPO-related proteins generated by the proteolytic cleavage of a single precursor (pre-PPO). The laticifer-specific pre-PPO protein contains a transit peptide that can target reporter proteins into chloroplasts when constitutively expressed in dandelion protoplasts, perhaps indicating the presence of structures similar to plastids in laticifers, which lack genuine chloroplasts. Silencing the PPO gene by constitutive RNA interference in transgenic plants reduced PPO activity compared with wild-type controls, allowing T. kok-saghyz RNA interference lines to expel four to five times more latex than controls. Latex fluidity analysis in silenced plants showed a strong correlation between residual PPO activity and the coagulation rate, indicating that laticifer-specific PPO plays a major role in latex coagulation and wound sealing in dandelions. In contrast, very little PPO activity is found in the latex of the rubber tree Hevea brasiliensis, suggesting functional divergence of latex proteins during plant evolution.

  7. RNA interference silencing of CHS greatly alters the growth pattern of apple (Malus x domestica).

    Science.gov (United States)

    Dare, Andrew P; Hellens, Roger P

    2013-08-01

    Plants produce a vast array of phenolic compounds which are essential for their survival on land. One major class of polyphenols are the flavonoids and their formation is dependent on the enzyme chalcone synthase (CHS). In a recent study we silenced the CHS genes of apple (Malus × domestica Borkh.) and observed a loss of pigmentation in the fruit skin, flowers and stems. More surprisingly, highly silenced lines were significantly reduced in size, with small leaves and shortened internode lengths. Chemical analysis also revealed that the transgenic shoots contained greatly reduced concentrations of flavonoids which are known to modulate auxin flow. An auxin transport study verified this, with an increased auxin transport in the CHS-silenced lines. Overall, these findings suggest that auxin transport in apple has adapted to take place in the presence of high endogenous concentrations of flavonoids. Removal of these compounds therefore results in abnormal auxin movement and a highly disrupted growth pattern.

  8. Generation of tobacco lines with widely different reduction in nicotine levels via RNA silencing approaches

    Indian Academy of Sciences (India)

    Peng Wang; Zhifeng Liang; Jia Zeng Wenchao; Wenchao Li; Xiaofen Sun; Zhiqi Miao; Kexuan Tang

    2008-06-01

    Issues related to the nicotine content of tobacco have been public concerns. Several reports have described decreasing nicotine levels by silencing the putrescine N-methyltransferase (PMT) genes, but the reported variations of nicotine levels among transgenic lines are relatively low in general. Here we describe the generation in tobacco (Nicotiana tabacum) lines with widely different, reduced nicotine levels using three kinds of RNA-silencing approaches. The relative efficacies of suppression were compared among the three approaches regarding the aspect of nicotine level in tobacco leaves. By suppressing expression of the PMT genes, over 200 transgenic lines were obtained with nicotine levels reduced by 9.1–96.7%. RNA interference (RNAi) was the most efficient method of reducing the levels of nicotine, whereas cosuppression and antisense methods were less effective. This report gives clues to the efficient generation of plants with a variety of metabolite levels, and the results demonstrate the relative efficiencies of various RNA-silencing methods.

  9. Conservation of miRNA-mediated silencing mechanisms across 600 million years of animal evolution

    Science.gov (United States)

    Mauri, Marta; Kirchner, Marieluise; Aharoni, Reuven; Ciolli Mattioli, Camilla; van den Bruck, David; Gutkovitch, Nadya; Modepalli, Vengamanaidu; Selbach, Matthias; Moran, Yehu; Chekulaeva, Marina

    2017-01-01

    Our current knowledge about the mechanisms of miRNA silencing is restricted to few lineages such as vertebrates, arthropods, nematodes and land plants. miRNA-mediated silencing in bilaterian animals is dependent on the proteins of the GW182 family. Here, we dissect the function of GW182 protein in the cnidarian Nematostella, separated by 600 million years from other Metazoa. Using cultured human cells, we show that Nematostella GW182 recruits the CCR4-NOT deadenylation complexes via its tryptophan-containing motifs, thereby inhibiting translation and promoting mRNA decay. Further, similarly to bilaterians, GW182 in Nematostella is recruited to the miRNA repression complex via interaction with Argonaute proteins, and functions downstream to repress mRNA. Thus, our work suggests that this mechanism of miRNA-mediated silencing was already active in the last common ancestor of Cnidaria and Bilateria. PMID:27604873

  10. Industrial Membrane Filtration and Short-bed Fractal Separation Systems for Separating Monomers from Heterogeneous Plant Material

    Energy Technology Data Exchange (ETDEWEB)

    Kearney, M; Kochergin, V; Hess, R; Foust, T; Herbst, R; Mann, N

    2005-03-31

    Large-scale displacement of petroleum will come from low-cost cellulosic feedstocks such as straw and corn stover crop residues. This project has taken a step toward making this projection a reality by reducing capital and energy costs, the two largest cost factors associated with converting cellulosic biomass to chemicals and fuels. The technology exists for using acid or enzyme hydrolysis processes to convert biomass feedstock (i.e., waste cellulose such as straw, corn stover, and wood) into their base monomeric sugar building blocks, which can, in turn, be processed into chemicals and fuels using a number of innovative fermentation technologies. However, while these processes are technically possible, practical and economic barriers make these processes only marginally feasible or not feasible at all. These barriers are due in part to the complexity and large fixed and recurring capital costs of unit operations including filtration, chromatographic separation, and ion exchange. This project was designed to help remove these barriers by developing and implementing new purification and separation technologies that will reduce the capital costs of the purification and chromatographic separation units by 50% to 70%. The technologies fundamental to these improvements are: (a) highly efficient clarification and purification systems that use screening and membrane filtration to eliminate suspended solids and colloidal material from feed streams and (b) fractal technology based chromatographic separation and ion exchange systems that can substitute for conventional systems but at much smaller size and cost. A non-hazardous ''raw sugar beet juice'' stream (75 to 100 gal/min) was used for prototype testing of these technologies. This raw beet juice stream from the Amalgamated Sugar LLC plant in Twin Falls, Idaho contained abrasive materials and membrane foulants. Its characteristics were representative of an industrial-scale heterogeneous plant extract

  11. The p122 subunit of Tobacco Mosaic Virus replicase is a potent silencing suppressor and compromises both small interfering RNA- and microRNA-mediated pathways.

    Science.gov (United States)

    Csorba, Tibor; Bovi, Aurelie; Dalmay, Tamás; Burgyán, József

    2007-11-01

    One of the functions of RNA silencing in plants is to defend against molecular parasites, such as viruses, retrotransposons, and transgenes. Plant viruses are inducers, as well as targets, of RNA silencing-based antiviral defense. Replication intermediates or folded viral RNAs activate RNA silencing, generating small interfering RNAs (siRNAs), which are the key players in the antiviral response. Viruses are able to counteract RNA silencing by expressing silencing-suppressor proteins. It has been shown that many of the identified silencing-suppressor proteins bind long double-stranded RNA or siRNAs and thereby prevent assembly of the silencing effector complexes. In this study, we show that the 122-kDa replicase subunit (p122) of crucifer-infecting Tobacco mosaic virus (cr-TMV) is a potent silencing-suppressor protein. We found that the p122 protein preferentially binds to double-stranded 21-nucleotide (nt) siRNA and microRNA (miRNA) intermediates with 2-nt 3' overhangs inhibiting the incorporation of siRNA and miRNA into silencing-related complexes (e.g., RNA-induced silencing complex [RISC]) both in vitro and in planta but cannot interfere with previously programmed RISCs. In addition, our results also suggest that the virus infection and/or sequestration of the siRNA and miRNA molecules by p122 enhances miRNA accumulation despite preventing its methylation. However, the p122 silencing suppressor does not prevent the methylation of certain miRNAs in hst-15 mutants, in which the nuclear export of miRNAs is compromised.

  12. Epigenetic chromatin silencing: bistability and front propagation

    Science.gov (United States)

    Sedighi, Mohammad; Sengupta, Anirvan M.

    2007-12-01

    The role of post-translational modification of histones in eukaryotic gene regulation is well recognized. Epigenetic silencing of genes via heritable chromatin modifications plays a major role in cell fate specification in higher organisms. We formulate a coarse-grained model of chromatin silencing in yeast and study the conditions under which the system becomes bistable, allowing for different epigenetic states. We also study the dynamics of the boundary between the two locally stable states of chromatin: silenced and unsilenced. The model could be of use in guiding the discussion on chromatin silencing in general. In the context of silencing in budding yeast, it helps us understand the phenotype of various mutants, some of which may be non-trivial to see without the help of a mathematical model. One such example is a mutation that reduces the rate of background acetylation of particular histone side chains that competes with the deacetylation by Sir2p. The resulting negative feedback due to a Sir protein depletion effect gives rise to interesting counter-intuitive consequences. Our mathematical analysis brings forth the different dynamical behaviors possible within the same molecular model and guides the formulation of more refined hypotheses that could be addressed experimentally.

  13. Glutathione S-transferases and malondialdehyde in the liver of NOD mice on short-term treatment with plant mixture extract P-9801091.

    Science.gov (United States)

    Petlevski, R; Hadzija, M; Slijepcević, M; Juretić, D; Petrik, J

    2003-04-01

    Changes in the concentration of glutathione S-transferases (GSTs) and malondialdehyde (MDA) were assessed in the liver of normal and diabetic NOD mice with and without treatment with the plant extract P-9801091. The plant extract P-9801091 is an antihyperglycaemic preparation containing Myrtilli folium (Vaccinium myrtillus L.), Taraxaci radix (Taraxacum of fi cinale Web.), Cichorii radix (Cichorium intybus L.), Juniperi fructus (Juniperus communis L.), Centaurii herba (Centaurium umbellatum Gilib.), Phaseoli pericarpium (Phaseolus vulgaris L.), Millefoliiherba (Achillea millefolium L.), Mori folium (Morus nigra L.), Valerianae radix (Valeriana of ficinalis L.) and Urticae herba et radix (Urtica dioica L). Hyperglycaemia in diabetes mellitus is responsible for the development of oxidative stress (via glucose auto-oxidation and protein glycation), which is characterized by increased lipid peroxide production (MDA is a lipid peroxidation end product) and/or decreased antioxidative defence (GST in the liver is predominantly an alpha enzyme, which has antioxidative activity). The catalytic concentration of GSTs in the liver was significantly reduced in diabetic NOD mice compared with normal NOD mice (p < 0.01), while the concentration of MDA showed a rising tendency (not significant). The results showed that statistically significant changes in antioxidative defence occurred in the experimental model of short-term diabetes mellitus. A 7-day treatment with P-9801091 plant extract at a dose of 20 mg/kg body mass led to a significant increase in the catalytic concentration of GSTs in the liver of diabetic NOD mice (p < 0.01) and a decrease in MDA concentration (not significant), which could be explained by its antihyperglycaemic effect. Copyright 2003 John Wiley & Sons, Ltd.

  14. Comprehensive Annotation of Physcomitrella patens Small RNA Loci Reveals That the Heterochromatic Short Interfering RNA Pathway Is Largely Conserved in Land Plants.

    Science.gov (United States)

    Coruh, Ceyda; Cho, Sung Hyun; Shahid, Saima; Liu, Qikun; Wierzbicki, Andrzej; Axtell, Michael J

    2015-08-01

    Many plant small RNAs are sequence-specific negative regulators of target mRNAs and/or chromatin. In angiosperms, the two most abundant endogenous small RNA populations are usually 21-nucleotide microRNAs (miRNAs) and 24-nucleotide heterochromatic short interfering RNAs (siRNAs). Heterochromatic siRNAs are derived from repetitive regions and reinforce DNA methylation at targeted loci. The existence and extent of heterochromatic siRNAs in other land plant lineages has been unclear. Using small RNA-sequencing (RNA-seq) of the moss Physcomitrella patens, we identified 1090 loci that produce mostly 23- to 24-nucleotide siRNAs. These loci are mostly in intergenic regions with dense DNA methylation. Accumulation of siRNAs from these loci depends upon P. patens homologs of DICER-LIKE3 (DCL3), RNA-DEPENDENT RNA POLYMERASE2, and the largest subunit of DNA-DEPENDENT RNA POLYMERASE IV, with the largest subunit of a Pol V homolog contributing to expression at a smaller subset of the loci. A MINIMAL DICER-LIKE (mDCL) gene, which lacks the N-terminal helicase domain typical of DCL proteins, is specifically required for 23-nucleotide siRNA accumulation. We conclude that heterochromatic siRNAs, and their biogenesis pathways, are largely identical between angiosperms and P. patens, with the notable exception of the P. patens-specific use of mDCL to produce 23-nucleotide siRNAs. © 2015 American Society of Plant Biologists. All rights reserved.

  15. Virus-induced silencing of a tobacco deoxyhypusine synthase gene

    Institute of Scientific and Technical Information of China (English)

    WANG Hongzhi; MA Rongcai; LI Ruifen; WANG Guoying; WEI Jianhua

    2005-01-01

    A cDNA fragment corresponding to deoxyhypusine synthase gene NbDHS was isolated and cloned into potato virus X (PVX) vector for functional analysis in Nicotiana benthamiana by using virus-induced gene silencing (VIGS). Plants agroinfected with recombinant virus vector PVX-NbDHS exhibited an increase in leaf biomass, delay in natural leaf senescence and flowering time, and decrease in leaf chlorophyll content. Semi-quantitative RT-PCR and Northern analysis showed that the transcript level of DHS was significantly lower in PVX-NbDHS infected plants. At the same time, the expression for eIF-5A, the target proteins of DHS in N. benthamiana, was concomitantly suppressed by semi-quantitative RT-PCR and Western analysis. From the phenotypic feature of the infected plants and the reduced expression abundance of DHS and eIF-5A, we concluded that NbDHS plays important roles in plant growth, development and senescence. The possible application of DHS gene in genetic modification of crops and horticultural plants was discussed.

  16. Silence as a Response to Everyday Violence

    DEFF Research Database (Denmark)

    Gammeltoft, Tine

    2016-01-01

    Across the world, existing research indicates that many women respond with silence to marital abuse. This article offers an ethnographic investigation of the social and psychic forces behind Vietnamese women’s silencing of violence and a theoretical exploration of how the psychoanalytic concept...... of fantasy—understood as unconscious or subconscious mental processes—may contribute to the analysis of everyday violence and psychic distress. Distinguishing between what I term deliberate and subconscious silence, I explore the role that fantasy plays when Vietnamese women silently endure intimate partner...... violence. Closer ethnographic attention to the fantasy-constructions that sustain day-to-day lives can, I argue, strengthen the capacity of anthropology to comprehend how systems of everyday violence are upheld and rendered socially invisible....

  17. Protein actors sustaining arbuscular mycorrhizal symbiosis: underground artists break the silence.

    Science.gov (United States)

    Recorbet, Ghislaine; Abdallah, Cosette; Renaut, Jenny; Wipf, Daniel; Dumas-Gaudot, Eliane

    2013-07-01

    The roots of most land plants can enter a relationship with soil-borne fungi belonging to the phylum Glomeromycota. This symbiosis with arbuscular mycorrhizal (AM) fungi belongs to the so-called biotrophic interactions, involving the intracellular accommodation of a microorganism by a living plant cell without causing the death of the host. Although profiling technologies have generated an increasing depository of plant and fungal proteins eligible for sustaining AM accommodation and functioning, a bottleneck exists for their functional analysis as these experiments are difficult to carry out with mycorrhiza. Nonetheless, the expansion of gene-to-phenotype reverse genetic tools, including RNA interference and transposon silencing, have recently succeeded in elucidating some of the plant-related protein candidates. Likewise, despite the ongoing absence of transformation tools for AM fungi, host-induced gene silencing has allowed knockdown of fungal gene expression in planta for the first time, thus unlocking a technological limitation in deciphering the functional pertinence of glomeromycotan proteins during mycorrhizal establishment. This review is thus intended to draw a picture of our current knowledge about the plant and fungal protein actors that have been demonstrated to be functionally implicated in sustaining AM symbiosis mostly on the basis of silencing approaches.

  18. Speaking silence: the social construction of silence in autobiographical and cultural narratives.

    Science.gov (United States)

    Fivush, Robyn

    2010-02-01

    Voice and silence are socially constructed in conversational interactions between speakers and listeners that are influenced by canonical cultural narratives which define lives and selves. Arguing from feminist and sociocultural theories, I make a distinction between being silenced and being silent; when being silenced is contrasted with voice, it is conceptualised as imposed, and it signifies a loss of power and self. But silence can also be conceptualised as being silent, a shared understanding that need not be voiced. More specifically, culturally dominant narratives provide for shared understandings that can remain silent; deviations from the norm call for voice, and thus in this case silence is power and voice expresses loss of power. At both the cultural and the individual level, there are tensions between culturally dominant and prescriptive narratives and narratives of resistance and deviation, leading to an ongoing dialectic between voice and silence. I end with a discussion of why, ultimately, it matters what is voiced and what is silenced for memory, identity and well-being.

  19. Bioengineering RNA silencing across the life kingdoms.

    Science.gov (United States)

    Alvarez-Fernandez, R; Lopez-Gomollon, S; Lopez-Martinez, A F; Nicolas, F E

    2011-08-01

    RNA silencing negatively regulates gene expression at transcriptional and posttranscriptional levels, guided by small RNA molecules. It modulates core regulatory pathways across the eukaryotes, such as developmental processes or stress responses. The widespread existence of this phenomenon and the key pathways regulated have led to the development of a new technology based on the modification of gene expression, which has been applied successfully in different areas such as medicine or agriculture. Here we review the most important patents related to RNA silencing across the life kingdoms, including biotechnological applications into medicine, crop science and bioengineering.

  20. In planta assays involving epigenetically silenced genes reveal inhibition of cytosine methylation by genistein

    Directory of Open Access Journals (Sweden)

    Arase Sachiko

    2012-03-01

    Full Text Available Abstract Background Cytosine methylation is involved in epigenetic control of gene expression in a wide range of organisms. An increasing number of examples indicate that changing the frequency of cytosine methylation in the genome is a feasible tool to engineer novel traits in plants. Although demethylating effects of compounds have been analyzed in human cultured cells in terms of suppressing cancer, their effect in plant cells has not been analyzed extensively. Here, we developed in planta assay systems to detect inhibition of cytosine methylation using plants that contain a transgene transcriptionally silenced by an epigenetic mechanism. Results Seeds of two transgenic plants were used: a petunia line that has been identified as a revertant of the co-suppression of the chalcone synthase-A (CHS-A gene and contains CHS-A transgenes whose transcription is repressed; Nicotiana benthamiana plants that contain the green fluorescent protein (GFP reporter gene whose transcription is repressed through virus-induced transcriptional gene silencing. Seeds of these plants were sown on a medium that contained a demethylating agent, either 5-azacytidine or trichostatin A, and the restoration of the transcriptionally active state of the transgene was detected in seedlings. Using these systems, we found that genistein, a major isoflavonoid compound, inhibits cytosine methylation, thus restoring transgene transcription. Genistein also restored the transcription of an epigenetically silenced endogenous gene in Arabidopsis plants. Conclusions Our assay systems allowed us to assess the inhibition of cytosine methylation, in particular of maintenance of methylation, by compounds in plant cells. These results suggest a novel role of flavonoids in plant cells and that genistein is useful for modifying the epigenetic state of plant genomes.

  1. Tobacco calmodulin-like protein provides secondary defense by binding to and directing degradation of virus RNA silencing suppressors

    OpenAIRE

    Nakahara, Kenji S; Masuta, Chikara; Yamada, Syouta; Shimura, Hanako; KASHIHARA, Yukiko; Wada, Tomoko S.; Meguro, Ayano; Goto, Kazunori; Tadamura, Kazuki; Sueda, Kae; Sekiguchi, Toru; Shao, Jun; Itchoda, Noriko; Matsumura, Takeshi; Igarashi, Manabu

    2012-01-01

    RNA silencing (RNAi) induced by virus-derived double-stranded RNA (dsRNA), which is in a sense regarded as a pathogen-associated molecular pattern (PAMP) of viruses, is a general plant defense mechanism. To counteract this defense, plant viruses express RNA silencing suppressors (RSSs), many of which bind to dsRNA and attenuate RNAi. We showed that the tobacco calmodulin-like protein, rgs-CaM, counterattacked viral RSSs by binding to their dsRNA-binding domains and sequestering them from inhi...

  2. Investigations of barley stripe mosaic virus as a gene silencing vector in barley roots and in Brachypodium distachyon and oat

    DEFF Research Database (Denmark)

    Pacak, Andrzej; Geisler, Katrin; Jørgensen, Bodil;

    2010-01-01

    -expressed genes we wanted to explore the potential of BSMV for silencing genes in root tissues. Furthermore, the newly completed genome sequence of the emerging cereal model species Brachypodium distachyon as well as the increasing amount of EST sequence information available for oat (Avena species) have created...... the wealth of genome information in the new cereal model plant B. distachyon. On the other hand, the silencing induced by BSMV in oat seemed too weak to be of practical use. The new BSMV vectors modified for ligation-free cloning will allow rapid insertion of plant gene fragments for future experiments....

  3. Transfer time and source tracing in the soil - water- -plant system deciphered by the U-and Th-series short-lived nuclides

    Science.gov (United States)

    Rihs, S.; Pierret, M.; Chabaux, F.

    2011-12-01

    Because soils form at the critical interface between the lithosphere and the atmosphere, characterization of the dynamics occurring through this compartment represents an important goal for several scientific fields and/or human activities. However, this issue remains a challenge because soils are complex systems, where a continuous evolution of minerals and organic soil constituents occurs in response to interactions with waters and vegetation. This study aims to investigate the relevance of short-lived nuclides of U- and Th-series to quantify the transfer times and scheme of radionuclides through a soil - water - plant ecosystem. Activities of (226Ra), (228Ra) and (228Th), as well as the long-lived (232Th), were measured by TIMS and gamma-spectrometry in the major compartments of a forested soil section, i.e.: solid soil fractions (exchangeable fraction, secondary phases and inherited primary minerals), waters (seepage soil waters and a spring further down the watershed) and vegetation (fine and coarse roots of beech trees, young and mature leaves). The matching of these nuclides half-live to bio-geochemical processes time-scale and the relatively good chemical analogy of radium with calcium make these isotopes especially suitable to investigate either time or mechanism of transfers within a soil-water-plant system. Indeed, the (228Ra/226Ra) isotopic ratios strongly differ in the range of samples, allowing quantifying the source and duration transfers. Analyses of the various solid soil fractions demonstrate a full redistribution of Ra isotopes between the inherited minerals and secondary soil phases. However, the transfer of these isotopes to the seepage water or to the tree roots does not follow a simple and obvious scheme. Both primary and secondary phases show to contribute to the dissolved radium. However, depending on the season, the tree leaves degradation also produces up to 70% of dissolved radium. Immobilization of a large part of this radium occurs

  4. Viral suppressors of RNA silencing hinder exogenous and endogenous small RNA pathways in Drosophila.

    Directory of Open Access Journals (Sweden)

    Bassam Berry

    Full Text Available BACKGROUND: In plants and insects, RNA interference (RNAi is the main responder against viruses and shapes the basis of antiviral immunity. Viruses counter this defense by expressing viral suppressors of RNAi (VSRs. While VSRs in Drosophila melanogaster were shown to inhibit RNAi through different modes of action, whether they act on other silencing pathways remained unexplored. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that expression of various plant and insect VSRs in transgenic flies does not perturb the Drosophila microRNA (miRNA pathway; but in contrast, inhibits antiviral RNAi and the RNA silencing response triggered by inverted repeat transcripts, and injection of dsRNA or siRNA. Strikingly, these VSRs also suppressed transposon silencing by endogenous siRNAs (endo-siRNAs. CONCLUSIONS/SIGNIFICANCE: Our findings identify VSRs as tools to unravel small RNA pathways in insects and suggest a cosuppression of antiviral RNAi and endo-siRNA silencing by viruses during fly infections.

  5. Development of Virus-Induced Gene Expression and Silencing Vector Derived from Grapevine Algerian Latent Virus

    Directory of Open Access Journals (Sweden)

    Sang-Ho Park

    2016-08-01

    Full Text Available Grapevine Algerian latent virus (GALV is a member of the genus Tombusvirus in the Tombusviridae and infects not only woody perennial grapevine plant but also herbaceous Nicotiana benthamiana plant. In this study, we developed GALV-based gene expression and virus-induced gene silencing (VIGS vectors in N. benthamiana. The GALV coat protein deletion vector, pGMG, was applied to express the reporter gene, green fluorescence protein (GFP, but the expression of GFP was not detected due to the necrotic cell death on the infiltrated leaves. The p19 silencing suppressor of GALV was engineered to inactivate its expression and GFP was successfully expressed with unrelated silencing suppressor, HC-Pro, from soybean mosaic virus. The pGMG vector was used to knock down magnesium chelatase (ChlH gene in N. benthamaina and the silencing phenotype was clearly observed on systemic leaves. Altogether, the GALV-derived vector is expected to be an attractive tool for useful gene expression and VIGS vectors in grapevine as well as N. benthamiana.

  6. Development of Virus-Induced Gene Expression and Silencing Vector Derived from Grapevine Algerian Latent Virus.

    Science.gov (United States)

    Park, Sang-Ho; Choi, Hoseong; Kim, Semin; Cho, Won Kyong; Kim, Kook-Hyung

    2016-08-01

    Grapevine Algerian latent virus (GALV) is a member of the genus Tombusvirus in the Tombusviridae and infects not only woody perennial grapevine plant but also herbaceous Nicotiana benthamiana plant. In this study, we developed GALV-based gene expression and virus-induced gene silencing (VIGS) vectors in N. benthamiana. The GALV coat protein deletion vector, pGMG, was applied to express the reporter gene, green fluorescence protein (GFP), but the expression of GFP was not detected due to the necrotic cell death on the infiltrated leaves. The p19 silencing suppressor of GALV was engineered to inactivate its expression and GFP was successfully expressed with unrelated silencing suppressor, HC-Pro, from soybean mosaic virus. The pGMG vector was used to knock down magnesium chelatase (ChlH) gene in N. benthamaina and the silencing phenotype was clearly observed on systemic leaves. Altogether, the GALV-derived vector is expected to be an attractive tool for useful gene expression and VIGS vectors in grapevine as well as N. benthamiana.

  7. Surprised by Bird, Bard, and Bach: Language, Silence, and Transcendence.

    Science.gov (United States)

    Suhor, Charles

    1991-01-01

    Argues the importance of the relationships among silence and literature, the arts, and other experiences that point toward transcendence. Suggests that English teachers can expand the repertoire of classroom activities and teaching techniques that make use of silence. (KEH)

  8. Embracing Silence and the Emptiness between Unspoken Words

    Science.gov (United States)

    VanSlyke-Briggs, Kjersti

    2014-01-01

    This article examines the use of silence as a constructive teaching tool in the classroom rather than as a punitive measure. The author offers suggestions for the inclusion of silence to benefit students specifically in a literature high school classroom.

  9. Silence and Sound in Kurosawa's Throne of Blood

    National Research Council Canada - National Science Library

    Jin, Lei; Jin, Lei

    2004-01-01

    .... By examining closely a few dramatic moments of the film, Lei demonstrates that silence and the interaction between silence, natural sound, and Noh music enhance the effect of Kurosawa's visual images...

  10. Assessing the tobacco-rattle-virus-based vectors system as an efficient gene silencing technique in Datura stramonium (Solanaceae).

    Science.gov (United States)

    Eftekhariyan Ghamsari, Mohammad Reza; Karimi, Farah; Mousavi Gargari, Seyed Latif; Hosseini Tafreshi, Seyed Ali; Salami, Seyed Alireza

    2014-12-01

    Datura stramonium is a well-known medicinal plant, which is important for its alkaloids. There are intrinsic limitations for the natural production of alkaloids in plants; metabolic engineering methods can be effectively used to conquer these limitations. In order for this the genes involved in corresponding pathways need to be studied. Virus-Induced Gene Silencing is known as a functional genomics technique to knock-down expression of endogenous genes. In this study, we silenced phytoene desaturase as a marker gene in D. stramonium in a heterologous and homologous manner by tobacco-rattle-virus-based VIGS vectors. Recombinant TRV vector containing pds gene from D. stramonium (pTRV2-Dspds) was constructed and injected into seedlings. The plants injected with pTRV2-Dspds showed photobleaching 2 weeks after infiltration. Spectrophotometric analysis demonstrated that the amount of chlorophylls and carotenoids in leaves of the bleached plants decreased considerably compared to that of the control plants. Semi-Quantitative RT-PCR results also confirmed that the expression of pds gene in the silenced plants was significantly reduced in comparison with the control plants. The results showed that the viral vector was able to influence the levels of total alkaloid content in D. stramonium. Our results illustrated that TRV-based VIGS vectors are able to induce effective and reliable functional gene silencing in D. stramonium as an alternative tool for studying the genes of interest in this plant, such as the targeted genes in tropane alkaloid biosynthetic pathway. The present work is the first report of establishing VIGS as an efficient method for transient silencing of any gene of interest in D. stramonium.

  11. Separation of isomeric short-chain acyl-CoAs in plant matrices using ultra-performance liquid chromatography coupled with tandem mass spectrometry.

    Science.gov (United States)

    Purves, Randy W; Ambrose, Stephen J; Clark, Shawn M; Stout, Jake M; Page, Jonathan E

    2015-02-01

    Acyl coenzyme A (acyl-CoA) thioesters are important intermediates in cellular metabolism and being able to distinguish among them is critical to fully understanding metabolic pathways in plants. Although significant advances have been made in the identification and quantification of acyl-CoAs using liquid chromatography tandem mass spectrometry (LC-MS/MS), separation of isomeric species such as isobutyryl- and n-butyrl-CoA has remained elusive. Here we report an ultra-performance liquid chromatography (UPLC)-MS/MS method for quantifying short-chain acyl-CoAs including isomeric species n-butyryl-CoA and isobutyryl-CoA as well as n-valeryl-CoA and isovaleryl-CoA. The method was applied to the analysis of extracts of hop (Humulus lupulus) and provided strong evidence for the existence of an additional structural isomer of valeryl-CoA, 2-methylbutyryl-CoA, as well as an unexpected isomer of hexanoyl-CoA. The results showed differences in the acyl-CoA composition among varieties of Humulus lupulus, both in glandular trichomes and cone tissues. When compared with the analysis of hemp (Cannabis sativa) extracts, the contribution of isobutyryl-CoAs in hop was greater as would be expected based on the downstream polyketide products. Surprisingly, branched chain valeryl-CoAs (isovaleryl-CoA and 2-methylbutyryl-CoA) were the dominant form of valeryl-CoAs in both hop and hemp. The capability to separate these isomeric forms will help to understand biochemical pathways leading to specialized metabolites in plants.

  12. Plant growth controls short-term changes in soil organic carbon (SOC) stocks of croplands - new insights from the CarboZALF experiment

    Science.gov (United States)

    Hoffmann, Mathias; Jurisch, Nicole; Garcia Alba, Joana; Albiac Borraz, Elisa; Schmidt, Marten; Verch, Gernot; Sommer, Michael; Augustin, Jürgen

    2016-04-01

    The long-term influence of crop rotations, climate conditions or soil type on soil organic carbon stock (SOC) patterns and gaseous C emissions of agricultural landscapes is widely recognized. However, the question of short-term seasonal changes in SOC within these areas remains unclear. A main reason for this is the detection problem of temporal and spatial variability in gaseous C exchange and thus, changes in SOC stocks (ΔSOC) in a high resolution. This study introduces dynamic C balances as a method to obtain seasonal changes in SOC stocks. Dynamic C balances were calculated by a combination of automatic chamber CO2 exchange measurements and empirical biomass models. Measurements were performed for three consecutive years at a colluvial depression (Colluvic Regosol) in the hummocky ground moraine landscape of NE Germany (CarboZALF experimental site). The investigated crop rotation was maize, winter fodder rye, maize, winter fodder rye, and sudangrass. The site is characterized by a gradient in ground water level (GWL) and related spatial heterogeneity in soil properties, such as SOC as well as soil nitrogen (Nt) stocks. Modelled dynamic C balances reveal that up to 79% of the standard deviation of estimated annual ΔSOC between single chambers emerged during the main period of crop growth (three months in summer). No significant changes in ΔSOC were detected outside the growing season. Instead, differences between chambers remain constant despite ΔSOC dynamics. Environmental variables (Nt stocks of Ap horizon and GWL), affecting plant-mediated C sequestration, explained up to 95% of temporal and spatial variability in CO2 exchange and ΔSOC. Thus, plant activities were the major catalyst for small scale differences in annual ΔSOC of croplands.

  13. Cannabinoid Type 1 Receptors Transiently Silence Glutamatergic Nerve Terminals of Cultured Cerebellar Granule Cells

    Science.gov (United States)

    Ramírez-Franco, Jorge; Bartolomé-Martín, David; Alonso, Beatris; Torres, Magdalena; Sánchez-Prieto, José

    2014-01-01

    Cannabinoid receptors are the most abundant G protein-coupled receptors in the brain and they mediate retrograde short-term inhibition of neurotransmitter release, as well as long-term depression of synaptic transmission at many excitatory synapses. The induction of presynaptically silent synapses is a means of modulating synaptic strength, which is important for synaptic plasticity. Persistent activation of cannabinoid type 1 receptors (CB1Rs) mutes GABAergic terminals, although it is unclear if CB1Rs can also induce silencing at glutamatergic synapses. Cerebellar granule cells were transfected with VGLUT1-pHluorin to visualise the exo-endocytotic cycle. We found that prolonged stimulation (10 min) of cannabinoid receptors with the agonist HU-210 induces the silencing of previously active synapses. However, the presynaptic silencing induced by HU-210 is transient as it reverses after 20 min. cAMP with forskolin prevented CB1R-induced synaptic silencing, via activation of the Exchange Protein directly Activated by cAMP (Epac). Furthermore, Epac activation accelerated awakening of already silent boutons. Electron microscopy revealed that silencing was associated with synaptic vesicle (SV) redistribution within the nerve terminal, which diminished the number of vesicles close to the active zone of the plasma membrane. Finally, by combining functional and immunocytochemical approaches, we observed a strong correlation between the release capacity of the nerve terminals and RIM1α protein content, but not that of Munc13-1 protein. These results suggest that prolonged stimulation of cannabinoid receptors can transiently silence glutamatergic nerve terminals. PMID:24533119

  14. REDUCTION OF NOISE OF ENVIRONMENTAL POLLUTION BY INSTALLING SILENCERS

    Directory of Open Access Journals (Sweden)

    Gorin V. A.

    2016-05-01

    Full Text Available The article describes the sources of noise Yeisk thermal power plant (TPP in excess of the permissible sound pressure levels in homes on the street. Gorky, 25. Eisk TPP is located near the residential area, where the permissible noise level standards adopted much more stringent than in the power plants. Prolonged exposure to noise leads to human disease noise disease. The scheme of movement of exhaust gases from the thermal power plant generating units Yeisk. Analysis of measurements of noise characteristics of main and auxiliary equipment showed that one of the main sources are sectioned estuaries double-barrel pipe height of 27 m and slices estuaries pipes emergency explosive valves flues installed on the roof at a height of 17 m. The previous Noise reduction nozzles that emit noise uniformly in all directions are replaced by advanced, whose index changed direction estuaries sections double-barrel tubes. This will change the level of radiated noise in residential development. If you change the angle of orientation of 135°-180°, the noise level in residential construction decreased by 7-10 dB. Shows a photograph of thermal power plants, residential buildings, the old and improved silencers

  15. The Analysis of Silence in Conflict Talk with Face Theory

    Institute of Scientific and Technical Information of China (English)

    罗丹

    2016-01-01

    Silence and noisy speech can be functionally equivalent in the conflict. Sometimes the more serious the problem is, the more likely that conversationalists will use silence in the utterance because silence stops conflict evolving into violence. In the context of potentially explosive arguments, pauses or silences prevent the conflict from exploding and destroying the possibility of continuing the relationship. Thus the participant’s face will be saved.

  16. Veiled Word(s) – Sacred Silence

    DEFF Research Database (Denmark)

    Isar, Nicoletta

    2014-01-01

    or secret prayer, and divine silence, which are at the very centre of the Byzantine altar. The main focus is to investigate the liminal nature of the Mystery, manifested through concealing-revealing devices, which are thresholds in the liturgical participation of the Byzantine subject. Fear and secrecy...

  17. Parenting a Precocious Preschooler: Breaking the Silence

    Science.gov (United States)

    Fish, Leigh Ann

    2016-01-01

    Precocity in the very young should be a valid topic of discussion in parental and educational circles, yet too frequently those conversations are slow to occur or are absent altogether. Many parents and educators remain silent about raising and nurturing precocious preschoolers, and author Leigh Ann Fish believe that the silence is due to a lack…

  18. Veiled Word(s) – Sacred Silence

    DEFF Research Database (Denmark)

    Isar, Nicoletta

    2014-01-01

    or secret prayer, and divine silence, which are at the very centre of the Byzantine altar. The main focus is to investigate the liminal nature of the Mystery, manifested through concealing-revealing devices, which are thresholds in the liturgical participation of the Byzantine subject. Fear and secrecy...

  19. Ideas for Creating and Overcoming Student Silences

    Science.gov (United States)

    Woods, Donald R.; Sheardown, Heather

    2009-01-01

    The key idea is that 50 minutes of teacher talk with passive student listening is relatively ineffective in developing student learning. Teachers can create silences for productive active student learning. Students can also change from passive listeners to active talker-discussers of their learning. Ideas are given about how to overcome silences…

  20. Silence in the second language classroom

    CERN Document Server

    King, J

    2013-01-01

    Why are second language learners in Japan's universities so silent? This book investigates the perplexing but intriguing phenomenon of classroom silence and draws on ideas from psychology, sociolinguistics and anthropology to offer a unique insight into the reasons why some learners are either unable or unwilling to speak in a foreign language.

  1. Enabling photoperiodic control of flowering by timely chromatin silencing of the florigen gene.

    Science.gov (United States)

    He, Yuehui

    2015-01-01

    Many plants synchronize their flowering times with changing seasons to maximize reproductive success. A key seasonal cue is the change in day length (photoperiod), that induces the production of a systemic flowering signaling molecule called florigen. A major florigen component is FLOWERING LOCUS T (FT) or its orthologs. In the long-day plant Arabidopsis thaliana, FT expression is well known to be activated by the photoperiod pathway output specifically near dusk in long days; however, underappreciated is the importance of FT silencing at other times of the day, in enabling Arabidopsis to respond only to long days in flowering. We have recently reported that a plant-specific chromatin-silencing complex called EMF1c represses FT expression at times other than around dusk in long days to prevent its temporal ectopic expression from "spoiling" the long-day floral induction in Arabidopsis. Here I further discuss in other day-length sensitive plants the potential involvement of a chromatin mechanism similar to the Arabidopsis EMF1c-mediated silencing, in repressing the expression of FT orthologs to enable diverse photoperiodic control of flowering.

  2. The Sound of Silence: The Case of Virtual Team Organising

    Science.gov (United States)

    Panteli, N.; Fineman, S.

    2005-01-01

    In this paper we discuss the role of silence within a virtual organising context. The paper raises issues related to the construction of silence in the virtual team context and the implications it has on team interactions. By drawing upon existing studies on virtual teams, we argue that members' silence may not always have negative effects on team…

  3. Complete Genome Sequence of Bacillus megaterium Siphophage Silence.

    Science.gov (United States)

    Solis, Jonathan A; Farmer, Nicholas G; Cahill, Jesse L; Rasche, Eric S; Kuty Everett, Gabriel F

    2015-10-08

    Silence is a newly isolated siphophage that infects Bacillus megaterium, a soil bacterium that is used readily in research and commercial applications. A study of B. megaterium phage Silence will enhance our knowledge of the diversity of Bacillus phages. Here, we describe the complete genome sequence and annotated features of Silence. Copyright © 2015 Solis et al.

  4. After the Blackbird Whistles: Listening to Silence in Classrooms

    Science.gov (United States)

    Schultz, Katherine

    2010-01-01

    Background/Context: Students spend a large part of their time in schools in silence. However, teachers tend to spend most of their time attending to student talk. Anthropological and linguistic research has contributed to an understanding of silence in particular communities, offering explanations for students' silence in school. This research…

  5. Unpacking the Unspoken: Silence in Collective Memory and Forgetting

    Science.gov (United States)

    Vinitzky-Seroussi, Vered; Teeger, Chana

    2010-01-01

    Collective memory quite naturally brings to mind notions of mnemonic speech and representation. In this article, however, we propose that collective silences be thought of as a rich and promising arena through which to understand how groups deal with their collective pasts. In so doing, we explore two types of silence: overt silence and covert…

  6. 47 CFR 80.304 - Watch requirement during silence periods.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Watch requirement during silence periods. 80... Safety Watches § 80.304 Watch requirement during silence periods. Each ship station operating on... safety messages, ship stations must not transmit during the silence periods on 2182 kHz. ...

  7. Choosing Silence for Equality in and through Schooling

    Science.gov (United States)

    Lees, Helen E.

    2016-01-01

    This article considers silences and equality as combined from a theoretical perspective. Equality in and through chosen, deliberate and regular silence experience is seen as an equaliser: if no one is speaking no one can dominate. The article uses a bifurcated concept of silence: weak, negative forms and strong, positive forms. Only the strong…

  8. Unpacking the Unspoken: Silence in Collective Memory and Forgetting

    Science.gov (United States)

    Vinitzky-Seroussi, Vered; Teeger, Chana

    2010-01-01

    Collective memory quite naturally brings to mind notions of mnemonic speech and representation. In this article, however, we propose that collective silences be thought of as a rich and promising arena through which to understand how groups deal with their collective pasts. In so doing, we explore two types of silence: overt silence and covert…

  9. An Empirical Study on English Majors’ Silence in Class

    Institute of Scientific and Technical Information of China (English)

    Zhao; Lingzhi

    2014-01-01

    This paper aims to investigate the causes of English majors’silence in class and whether task-based approach can reduce silence by conducting an empirical study.The results indicates that students’self-esteem,motivation,personality and teachers’authority are the main causes of students’silence in class.

  10. Complete Genome Sequence of Bacillus megaterium Siphophage Silence

    OpenAIRE

    Solis, Jonathan A.; Farmer, Nicholas G.; Cahill, Jesse L.; Rasche, Eric S.; Kuty Everett, Gabriel F.

    2015-01-01

    Silence is a newly isolated siphophage that infects Bacillus megaterium, a soil bacterium that is used readily in research and commercial applications. A study of B. megaterium phage Silence will enhance our knowledge of the diversity of Bacillus phages. Here, we describe the complete genome sequence and annotated features of Silence.

  11. The Differences of Silence between Chinese and American Culture

    Institute of Scientific and Technical Information of China (English)

    巩飞

    2015-01-01

    Language is an important means of human communication; and silence can also convey a wealth of information.This paper will interpret the different definitions of silence phenomena between China and America and two different attitudes and representations of silence.It will help us to improve the effectiveness of communication.

  12. An Empirical Study on English Majors’Silence in Class

    Institute of Scientific and Technical Information of China (English)

    Zhao Lingzhi

    2014-01-01

    This paper aims to investigate the causes of English majors' silence in class and whether task-based approach can reduce silence by conducting an empirical study.The results indicates that students' self-esteem,motivation,personality and teachers' authority are the main causes of students' silence in class.

  13. Bioinformatics approaches for viral metagenomics in plants using short RNAs: model case of study and application to a Cicer arietinum population.

    Science.gov (United States)

    Pirovano, Walter; Miozzi, Laura; Boetzer, Marten; Pantaleo, Vitantonio

    2014-01-01

    Over the past years deep sequencing experiments have opened novel doors to reconstruct viral populations in a high-throughput and cost-effective manner. Currently a substantial number of studies have been performed which employ next generation sequencing techniques to either analyze known viruses by means of a reference-guided approach or to discover novel viruses using a de novo-based strategy. Taking advantage of the well-known Cymbidium ringspot virus we have carried out a comparison of different bioinformatics tools to reconstruct the viral genome based on 21-27 nt short (s)RNA sequencing with the aim to identify the most efficient pipeline. The same approach was applied to a population of plants constituting an ancient variety of Cicer arietinum with red seeds. Among the discovered viruses, we describe the presence of a Tobamovirus referring to the Tomato mottle mosaic virus (NC_022230), which was not yet observed on C. arietinum nor revealed in Europe and a viroid referring to Hop stunt viroid (NC_001351.1) never reported in chickpea. Notably, a reference sequence guided approach appeared the most efficient in such kind of investigation. Instead, the de novo assembly reached a non-appreciable coverage although the most prominent viral species could still be identified. Advantages and limitations of viral metagenomics analysis using sRNAs are discussed.

  14. Antiviral Defenses in Plants through Genome Editing

    Science.gov (United States)

    Romay, Gustavo; Bragard, Claude

    2017-01-01

    Plant–virus interactions based-studies have contributed to increase our understanding on plant resistance mechanisms, providing new tools for crop improvement. In the last two decades, RNA interference, a post-transcriptional gene silencing approach, has been used to induce antiviral defenses in plants with the help of genetic engineering technologies. More recently, the new genome editing systems (GES) are revolutionizing the scope of tools available to confer virus resistance in plants. The most explored GES are zinc finger nucleases, transcription activator-like effector nucleases, and clustered regularly interspaced short palindromic repeats/Cas9 endonuclease. GES are engineered to target and introduce mutations, which can be deleterious, via double-strand breaks at specific DNA sequences by the error-prone non-homologous recombination end-joining pathway. Although GES have been engineered to target DNA, recent discoveries of GES targeting ssRNA molecules, including virus genomes, pave the way for further studies programming plant defense against RNA viruses. Most of plant virus species have an RNA genome and at least 784 species have positive ssRNA. Here, we provide a summary of the latest progress in plant antiviral defenses mediated by GES. In addition, we also discuss briefly the GES perspectives in light of the rebooted debate on genetic modified organisms (GMOs) and the current regulatory frame for agricultural products involving the use of such engineering technologies. PMID:28167937

  15. Silence:An Effective Resistance in"No Name Woman"

    Institute of Scientific and Technical Information of China (English)

    戴淑琴

    2016-01-01

    "No Name Woman", written by Maxine Hong Kingston, depicts different life of Chinese or Chinese American women. They go through different life experiences, but their life experiences reflect the same attitude toward life that is silence. Is si-lence effective or not? By analyzing the textual contents, life experience of the aunt combining with contemporary social envi-ronment, the paper argues that silence is an effective resistance against patriarchal system. It illuminates the ways that resistance not only relies on violence, but also on silence and sometimes silence is more powerful than violence.

  16. A PHD-polycomb repressive complex 2 triggers the epigenetic silencing of FLC during vernalization.

    Science.gov (United States)

    De Lucia, Filomena; Crevillen, Pedro; Jones, Alexandra M E; Greb, Thomas; Dean, Caroline

    2008-11-04

    Vernalization, the acceleration of flowering by winter, involves cold-induced epigenetic silencing of Arabidopsis FLC. This process has been shown to require conserved Polycomb Repressive Complex 2 (PRC2) components including the Su(z)12 homologue, VRN2, and two plant homeodomain (PHD) finger proteins, VRN5 and VIN3. However, the sequence of events leading to FLC repression was unclear. Here we show that, contrary to expectations, VRN2 associates throughout the FLC locus independently of cold. The vernalization-induced silencing is triggered by the cold-dependent association of the PHD finger protein VRN5 to a specific domain in FLC intron 1, and this association is dependent on the cold-induced PHD protein VIN3. In plants returned to warm conditions, VRN5 distribution changes, and it associates more broadly over FLC, coincident with significant increases in H3K27me3. Biochemical purification of a VRN5 complex showed that during prolonged cold a PHD-PRC2 complex forms composed of core PRC2 components (VRN2, SWINGER [an E(Z) HMTase homologue], FIE [an ESC homologue], MSI1 [p55 homologue]), and three related PHD finger proteins, VRN5, VIN3, and VEL1. The PHD-PRC2 activity increases H3K27me3 throughout the locus to levels sufficient for stable silencing. Arabidopsis PHD-PRC2 thus seems to act similarly to Pcl-PRC2 of Drosophila and PHF1-PRC2 of mammals. These data show FLC silencing involves changed composition and dynamic redistribution of Polycomb complexes at different stages of the vernalization process, a mechanism with greater parallels to Polycomb silencing of certain mammalian loci than the classic Drosophila Polycomb targets.

  17. Virus-induced gene silencing as a tool for comparative functional studies in Thalictrum.

    Directory of Open Access Journals (Sweden)

    Verónica S Di Stilio

    Full Text Available Perennial woodland herbs in the genus Thalictrum exhibit high diversity of floral morphology, including four breeding and two pollination systems. Their phylogenetic position, in the early-diverging eudicots, makes them especially suitable for exploring the evolution of floral traits and the fate of gene paralogs that may have shaped the radiation of the eudicots. A current limitation in evolution of plant development studies is the lack of genetic tools for conducting functional assays in key taxa spanning the angiosperm phylogeny. We first show that virus-induced gene silencing (VIGS of a PHYTOENE DESATURASE ortholog (TdPDS can be achieved in Thalictrum dioicum with an efficiency of 42% and a survival rate of 97%, using tobacco rattle virus (TRV vectors. The photobleached leaf phenotype of silenced plants significantly correlates with the down-regulation of endogenous TdPDS (P<0.05, as compared to controls. Floral silencing of PDS was achieved in the faster flowering spring ephemeral T. thalictroides. In its close relative, T. clavatum, silencing of the floral MADS box gene AGAMOUS (AG resulted in strong homeotic conversions of floral organs. In conclusion, we set forth our optimized protocol for VIGS by vacuum-infiltration of Thalictrum seedlings or dormant tubers as a reference for the research community. The three species reported here span the range of floral morphologies and pollination syndromes present in Thalictrum. The evidence presented on floral silencing of orthologs of the marker gene PDS and the floral homeotic gene AG will enable a comparative approach to the study of the evolution of flower development in this group.

  18. Monitoring the neural activity of the state of mental silence while practicing Sahaja yoga meditation.

    Science.gov (United States)

    Hernández, Sergio E; Suero, José; Rubia, Katya; González-Mora, José L

    2015-03-01

    To identify the neural correlates of the state of mental silence as experienced through Sahaja yoga meditation. Nineteen experienced meditators underwent functional magnetic resonance imaging during three short consecutive meditation periods, contrasted with a control relaxation condition. Relative to baseline, at the beginning of the meditation sessions there was a significant increase of activation in bilateral inferior frontal and temporal regions. Activation became progressively more reduced with deeper meditation stages and in the last meditation session it became localized to the right inferior frontal cortex/ right insula and right middle/superior temporal cortex. Furthermore, right inferior frontal activation was directly associated with the subjective depth of the mental silence experience. Meditators appear to pass through an initial intense neural self-control process necessary to silence their mind. After this they experience relatively reduced brain activation concomitant with the deepening of the state of mental silence over right inferior frontal cortex, probably reflecting an effortless process of attentional contemplation associated with this state.

  19. Histone H4 deacetylation plays a critical role in early gene silencing during neuronal apoptosis

    Directory of Open Access Journals (Sweden)

    Schlamp Cassandra L

    2010-05-01

    Full Text Available Abstract Background Silencing of normal gene expression occurs early in the apoptosis of neurons, well before the cell is committed to the death pathway, and has been extensively characterized in injured retinal ganglion cells. The causative mechanism of this widespread change in gene expression is unknown. We investigated whether an epigenetic change in active chromatin, specifically histone H4 deacetylation, was an underlying mechanism of gene silencing in apoptotic retinal ganglion cells (RGCs following an acute injury to the optic nerve. Results Histone deacetylase 3 (HDAC3 translocates to the nuclei of dying cells shortly after lesion of the optic nerve and is associated with an increase in nuclear HDAC activity and widespread histone deacetylation. H4 in promoters of representative genes was rapidly and indiscriminately deacetylated, regardless of the gene examined. As apoptosis progressed, H4 of silenced genes remained deacetylated, while H4 of newly activated genes regained, or even increased, its acetylated state. Inhibition of retinal HDAC activity with trichostatin A (TSA was able to both preserve the expression of a representative RGC-specific gene and attenuate cell loss in response to optic nerve damage. Conclusions These data indicate that histone deacetylation plays a central role in transcriptional dysregulation in dying RGCs. The data also suggests that HDAC3, in particular, may feature heavily in apoptotic gene silencing.

  20. Destructive Role of Employee Silence in Organizational Success

    Directory of Open Access Journals (Sweden)

    Malikeh Beheshtifar

    2012-11-01

    Full Text Available Employees are regarded as major sources of change, creativity, learning, and innovation, which are critical factors to the success of organizations. However, many employees choose not to voice their opinions and concerns about matters in their organizations. Silence can convey approval and sharing or disfavor and opposition, thus becoming a pressure mechanism for both individuals and organizations. Through silence, organizational members suppress concerns about difficult or troubling personal as well as organizational issues. Moreover, there are three types of employee silence as Acquiescent Silence, Defensive Silence, and Pro-social Silence. Fear, embarrassment, narrow conceptions of ethical responsibility, implicated friends, lack of opportunity for voice, and lack of organizational political skills are factors to cause silence. Employee silence has many effects on the employees themselves. Indifferent employees, often products of ignored employee silence, tend to feel like cogs at machinery factories, developing the attitude “to get along, go along”. Indifferent employees cause the organization to lose money and function poorly. If employee silence does occur, communication suffers and as a result harms the overall functioning of the organization. However, it is not easy to break silence climate of employees and their managers. Meanwhile, it is suggested to regulate some rules for supporting the employees' attitudes, to make decisions about the work groups of the organizations and to establish some programs in order to improve the human resource management for training skills of decision – making.

  1. HC-Pro silencing suppressor significantly alters the gene expression profile in tobacco leaves and flowers

    Directory of Open Access Journals (Sweden)

    Lehto Kirsi

    2011-04-01

    Full Text Available Abstract Background RNA silencing is used in plants as a major defence mechanism against invasive nucleic acids, such as viruses. Accordingly, plant viruses have evolved to produce counter defensive RNA-silencing suppressors (RSSs. These factors interfere in various ways with the RNA silencing machinery in cells, and thereby disturb the microRNA (miRNA mediated endogene regulation and induce developmental and morphological changes in plants. In this study we have explored these effects using previously characterized transgenic tobacco plants which constitutively express (under CaMV 35S promoter the helper component-proteinase (HC-Pro derived from a potyviral genome. The transcript levels of leaves and flowers of these plants were analysed using microarray techniques (Tobacco 4 × 44 k, Agilent. Results Over expression of HC-Pro RSS induced clear phenotypic changes both in growth rate and in leaf and flower morphology of the tobacco plants. The expression of 748 and 332 genes was significantly changed in the leaves and flowers, respectively, in the HC-Pro expressing transgenic plants. Interestingly, these transcriptome alterations in the HC-Pro expressing tobacco plants were similar as those previously detected in plants infected with ssRNA-viruses. Particularly, many defense-related and hormone-responsive genes (e.g. ethylene responsive transcription factor 1, ERF1 were differentially regulated in these plants. Also the expression of several stress-related genes, and genes related to cell wall modifications, protein processing, transcriptional regulation and photosynthesis were strongly altered. Moreover, genes regulating circadian cycle and flowering time were significantly altered, which may have induced a late flowering phenotype in HC-Pro expressing plants. The results also suggest that photosynthetic oxygen evolution, sugar metabolism and energy levels were significantly changed in these transgenic plants. Transcript levels of S

  2. HC-Pro silencing suppressor significantly alters the gene expression profile in tobacco leaves and flowers.

    Science.gov (United States)

    Soitamo, Arto J; Jada, Balaji; Lehto, Kirsi

    2011-04-20

    RNA silencing is used in plants as a major defence mechanism against invasive nucleic acids, such as viruses. Accordingly, plant viruses have evolved to produce counter defensive RNA-silencing suppressors (RSSs). These factors interfere in various ways with the RNA silencing machinery in cells, and thereby disturb the microRNA (miRNA) mediated endogene regulation and induce developmental and morphological changes in plants. In this study we have explored these effects using previously characterized transgenic tobacco plants which constitutively express (under CaMV 35S promoter) the helper component-proteinase (HC-Pro) derived from a potyviral genome. The transcript levels of leaves and flowers of these plants were analysed using microarray techniques (Tobacco 4 × 44 k, Agilent). Over expression of HC-Pro RSS induced clear phenotypic changes both in growth rate and in leaf and flower morphology of the tobacco plants. The expression of 748 and 332 genes was significantly changed in the leaves and flowers, respectively, in the HC-Pro expressing transgenic plants. Interestingly, these transcriptome alterations in the HC-Pro expressing tobacco plants were similar as those previously detected in plants infected with ssRNA-viruses. Particularly, many defense-related and hormone-responsive genes (e.g. ethylene responsive transcription factor 1, ERF1) were differentially regulated in these plants. Also the expression of several stress-related genes, and genes related to cell wall modifications, protein processing, transcriptional regulation and photosynthesis were strongly altered. Moreover, genes regulating circadian cycle and flowering time were significantly altered, which may have induced a late flowering phenotype in HC-Pro expressing plants. The results also suggest that photosynthetic oxygen evolution, sugar metabolism and energy levels were significantly changed in these transgenic plants. Transcript levels of S-adenosyl-L-methionine (SAM) were also decreased in

  3. Host-Induced Silencing of Pathogenicity Genes Enhances Resistance to Fusarium oxysporum Wilt in Tomato.

    Science.gov (United States)

    Bharti, Poonam; Jyoti, Poonam; Kapoor, Priya; Sharma, Vandana; Shanmugam, V; Yadav, Sudesh Kumar

    2017-08-01

    This study presents a novel approach of controlling vascular wilt in tomato by RNAi expression directed to pathogenicity genes of Fusarium oxysporum f. sp. lycopersici. Vascular wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici leads to qualitative and quantitative loss of the crop. Limitation in the existing control measures necessitates the development of alternative strategies to increase resistance in the plants against pathogens. Recent findings paved way to RNAi, as a promising method for silencing of pathogenicity genes in fungus and provided effective resistance against fungal pathogens. Here, two important pathogenicity genes FOW2, a Zn(II)2Cys6 family putative transcription regulator, and chsV, a putative myosin motor and a chitin synthase domain, were used for host-induced gene silencing through hairpinRNA cassettes of these genes against Fusarium oxysporum f. sp. lycopersici. HairpinRNAs were assembled in appropriate binary vectors and transformed into tomato plant targeting FOW2 and chsV genes, for two highly pathogenic strains of Fusarium oxysporum viz. TOFOL-IHBT and TOFOL-IVRI. Transgenic tomatoes were analyzed for possible attainment of resistance in transgenic lines against fungal infection. Eight transgenic lines expressing hairpinRNA cassettes showed trivial disease symptoms after 6-8 weeks of infection. Hence, the host-induced posttranscriptional gene silencing of pathogenicity genes in transgenic tomato plants has enhanced their resistance to vascular wilt disease caused by Fusarium oxysporum.

  4. Disruption of Rpp1-mediated soybean rust immunity by virus-induced gene silencing.

    Science.gov (United States)

    Cooper, Bret; Campbell, Kimberly B; McMahon, Michael B; Luster, Douglas G

    2013-01-01

    Phakopsora pachyrhizi, a fungus that causes rust disease on soybean, has potential to impart significant yield loss and disrupt food security and animal feed production. Rpp1 is a soybean gene that confers immunity to soybean rust, and it is important to understand how it regulates the soybean defense system and to use this knowledge to protect commercial crops. It was previously discovered that some soybean proteins resembling transcription factors accumulate in the nucleus of Rpp1 soybeans. To determine if they contribute to immunity, Bean pod mottle virus was used to attenuate or silence the expression of their genes. Rpp1 plants subjected to virus-induced gene silencing exhibited reduced amounts of RNA for 5 of the tested genes, and the plants developed rust-like symptoms after subsequent inoculation with fungal spores. Symptoms were associated with the accumulation of rust fungal RNA and protein. Silenced plants also had reduced amounts of RNA for the soybean Myb84 transcription factor and soybean isoflavone O-methyltransferase, both of which are important to phenylpropanoid biosynthesis and lignin formation, crucial components of rust resistance. These results help resolve some of the genes that contribute to Rpp1-mediated immunity and improve upon the knowledge of the soybean defense system. It is possible that these genes could be manipulated to enhance rust resistance in otherwise susceptible soybean cultivars.

  5. The Marijuana Phenomenon: Contradictions and Silence.

    Science.gov (United States)

    Hall, Joanne M; Shattell, Mona M; McConnell, Elizabeth A

    2016-01-01

    The United States is trending toward more permissiveness regarding recreational and medicinal marijuana (MJ). Many conditions for which MJ is recommended, prescribed, or self-prescribed are symptoms that advanced practice nurses address daily. Yet, the silence of nursing scientists on ethics, practices, and policies regarding such clinical decisions is deafening. This is but one of many contradictions about MJ use that we discuss in this article. We do not propose to resolve these contradictions; that is left to the community of nurse scientists in interprofessional discourse. Collectively, we must explore these contradictions and, through evidence-based policy recommendations, overcome the silence about how providers view MJ, how it might be helpful, its risks, and cultural shifts that have accompanied a changed political/legal environment. Long term, we must close the gaps in the nursing knowledge base regarding MJ as it affects users and how it is used interventionally.

  6. DNA replication factor C1 mediates genomic stability and transcriptional gene silencing in Arabidopsis

    KAUST Repository

    Liu, Qian

    2010-07-01

    Genetic screening identified a suppressor of ros1-1, a mutant of REPRESSOR OF SILENCING1 (ROS1; encoding a DNA demethylation protein). The suppressor is a mutation in the gene encoding the largest subunit of replication factor C (RFC1). This mutation of RFC1 reactivates the unlinked 35S-NPTII transgene, which is silenced in ros1 and also increases expression of the pericentromeric Athila retrotransposons named transcriptional silent information in a DNA methylationindependent manner. rfc1 is more sensitive than the wild type to the DNA-damaging agent methylmethane sulphonate and to the DNA inter- and intra- cross-linking agent cisplatin. The rfc1 mutant constitutively expresses the G2/M-specific cyclin CycB1;1 and other DNA repair-related genes. Treatment with DNA-damaging agents mimics the rfc1 mutation in releasing the silenced 35S-NPTII, suggesting that spontaneously induced genomic instability caused by the rfc1 mutation might partially contribute to the released transcriptional gene silencing (TGS). The frequency of somatic homologous recombination is significantly increased in the rfc1 mutant. Interestingly, ros1 mutants show increased telomere length, but rfc1 mutants show decreased telomere length and reduced expression of telomerase. Our results suggest that RFC1 helps mediate genomic stability and TGS in Arabidopsis thaliana. © 2010 American Society of Plant Biologists.

  7. Silencing cinema: film censorship around the world

    OpenAIRE

    2013-01-01

    Why does oppression by censorship affect the film industry far more frequently than any other mass media? "Silencing Cinema" brings together the key issues and authors to examine instances of film censorship throughout the world. Including essays by some of today's leading film historians, the book offers groundbreaking historical research on film censorship in major film production countries, including the United States, the United Kingdom, Russia/Soviet Union, India, China, and Nigeria, amo...

  8. Contra les conspiracions fetes de silenci: dos textos que parlen de l'abús sexual a nenes

    Directory of Open Access Journals (Sweden)

    Meri Torras

    2010-06-01

    Full Text Available This article focuses on the silence surrounding child abuse in contemporary society. The invisibility of girls abuse is placed in the wider context of violence against women and in its diverse forms of expression. A claim is made for a new language that helps to articulate the different institutional spheres implicated: educational, social, legal and medical. Two texts that break away with this conspiracy of silence are analysed: the comic book by Bryan Talbot History of a Bat Rat (1999 and the short cartoon film Le chapeau/The Hat (1999 by Michèle de Cournoyer.

  9. Experimental studies of a drumlike silencer.

    Science.gov (United States)

    Choy, Y S; Huang, Lixi

    2002-11-01

    The theoretical finding of the broadband performance of a reactive silencer is validated experimentally. The silencer consists of two highly stretched membranes lining part of the duct and backed by two long and shallow cavities. The test rig was built with a small square duct of 5 cm in dimension, and each cavity is 5 cm deep and 25 cm long. Two types of metal foils, stainless steel and copper, were used, and the lowest membrane-to-air mass ratio was 1.3. A transmission loss in excess of 10 dB was achieved over more than one octave band. For one configuration close to the optimal parameters, the predicted ratio of the frequency band limits is 2.47, while the experiment gave 2.35. Three spectral peaks were found in the stopband, as predicted, but the peaks were broader than prediction, indicating the presence of significant sound energy dissipation mechanisms. Comparison with theoretical simulation shows that the cavity damping dominates over membrane friction. Tests using heavier membranes and membrane with different levels of tension also agree with predictions. Issues of practical implementation of the concept as a flow-through silencer are also addressed.

  10. DNA/RNA heteroduplex oligonucleotide for highly efficient gene silencing

    Science.gov (United States)

    Nishina, Kazutaka; Piao, Wenying; Yoshida-Tanaka, Kie; Sujino, Yumiko; Nishina, Tomoko; Yamamoto, Tsuyoshi; Nitta, Keiko; Yoshioka, Kotaro; Kuwahara, Hiroya; Yasuhara, Hidenori; Baba, Takeshi; Ono, Fumiko; Miyata, Kanjiro; Miyake, Koichi; Seth, Punit P.; Low, Audrey; Yoshida, Masayuki; Bennett, C. Frank; Kataoka, Kazunori; Mizusawa, Hidehiro; Obika, Satoshi; Yokota, Takanori

    2015-01-01

    Antisense oligonucleotides (ASOs) are recognized therapeutic agents for the modulation of specific genes at the post-transcriptional level. Similar to any medical drugs, there are opportunities to improve their efficacy and safety. Here we develop a short DNA/RNA heteroduplex oligonucleotide (HDO) with a structure different from double-stranded RNA used for short interfering RNA and single-stranded DNA used for ASO. A DNA/locked nucleotide acid gapmer duplex with an α-tocopherol-conjugated complementary RNA (Toc-HDO) is significantly more potent at reducing the expression of the targeted mRNA in liver compared with the parent single-stranded gapmer ASO. Toc-HDO also improves the phenotype in disease models more effectively. In addition, the high potency of Toc-HDO results in a reduction of liver dysfunction observed in the parent ASO at a similar silencing effect. HDO technology offers a novel concept of therapeutic oligonucleotides, and the development of this molecular design opens a new therapeutic field. PMID:26258894

  11. Silence and Voicing Accumulations in Italian Primary School Teachers With and Without Voice Disorders.

    Science.gov (United States)

    Bottalico, Pasquale; Graetzer, Simone; Astolfi, Arianna; Hunter, Eric J

    2017-03-01

    The relationship between the silence and voicing accumulations of primary school teachers and the teachers' clinical status was examined to determine whether more voicing accumulations and fewer silence accumulations were measured for the vocally unhealthy subjects than for the healthy subjects, which would imply more vocal loading and fewer short-term recovery moments. Twenty-six Italian primary school teachers were allocated by clinicians to three groups: (1) with organic voice disorders, (2) with subjectively mild organic alteration or functional voice symptoms, and (3) normal voice quality and physiology. Continuous silence and voicing periods were measured with the APM3200 during the teachers' 4-hour workdays. The accumulations were grouped into seven time intervals, ranging from 0.03-0.9 to 3.16-10 seconds, according to Italian prosody. The effects of group on silence and voicing accumulations were evaluated. Regarding silence accumulations, Group 1 accumulated higher values in intervals between 0.1 and 3.15 seconds than other groups, whereas Groups 2 and 3 did not differ from each other. Voicing accumulations between 0.17 and 3.15 seconds were higher for subjects with a structural disorder. A higher time dose was accumulated by these subjects (40.6%) than other subjects (Group 2, 31.9%; Group 3, 32.3%). Although previous research has suggested that a rest period of a few seconds may produce some vocal fatigue recovery, these results indicate that periods shorter than 3.16 seconds may not have an observable effect on recovery. The results provide insight into how vocal fatigue and vocal recovery may relate to voice disorders in occupational voice users. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

  12. Duration of voicing and silence periods of continuous speech in different acoustic environments.

    Science.gov (United States)

    Astolfi, Arianna; Carullo, Alessio; Pavese, Lorenzo; Puglisi, Giuseppina Emma

    2015-02-01

    This work deals with the duration of voicing and silence periods of continuous speech in rooms with very different reverberation times (RTs). Measurements were conducted using the Ambulatory Phonation Monitoring (APM) 3200 (Kaypentax, Montvale, NJ) and Voice-Care devices (developed at the Politecnico di Torino, Italy), both of which have a contact microphone placed on the base of the neck to detect skin vibrations during phonation. Six university professors and 22 university students made short laboratory monologs in which they explained something that they knew well to a listener 6 m away. Seven students also described a map with the intention of correctly explaining directions to a listener who drew the path on a blank chart. Longer speech samples were made by 25 primary school teachers in classrooms. A tendency to increase the voicing periods as the RT increased was on average observed for the university professors, the school teachers, and the university students who described a map. These students also showed longer silence periods than the students who made short monologs. The recognized trends concerned voice professionals or subjects who were highly motivated to make themselves understood in a perturbed speaking situation. Nonparametric statistical tests, which were applied to detect the differences in distributions of voicing and silence periods, have basically supported the findings.

  13. Investigations of barley stripe mosaic virus as a gene silencing vector in barley roots and in Brachypodium distachyon and oat

    Directory of Open Access Journals (Sweden)

    Nilsson Lena

    2010-11-01

    Full Text Available Abstract Background Gene silencing vectors based on Barley stripe mosaic virus (BSMV are used extensively in cereals to study gene function, but nearly all studies have been limited to genes expressed in leaves of barley and wheat. However since many important aspects of plant biology are based on root-expressed genes we wanted to explore the potential of BSMV for silencing genes in root tissues. Furthermore, the newly completed genome sequence of the emerging cereal model species Brachypodium distachyon as well as the increasing amount of EST sequence information available for oat (Avena species have created a need for tools to study gene function in these species. Results Here we demonstrate the successful BSMV-mediated virus induced gene silencing (VIGS of three different genes in barley roots, i.e. the barley homologues of the IPS1, PHR1, and PHO2 genes known to participate in Pi uptake and reallocation in Arabidopsis. Attempts to silence two other genes, the Pi transporter gene HvPht1;1 and the endo-β-1,4-glucanase gene HvCel1, in barley roots were unsuccessful, probably due to instability of the plant gene inserts in the viral vector. In B. distachyon leaves, significant silencing of the PHYTOENE DESATURASE (BdPDS gene was obtained as shown by photobleaching as well as quantitative RT-PCR analysis. On the other hand, only very limited silencing of the oat AsPDS gene was observed in both hexaploid (A. sativa and diploid (A. strigosa oat. Finally, two modifications of the BSMV vector are presented, allowing ligation-free cloning of DNA fragments into the BSMV-γ component. Conclusions Our results show that BSMV can be used as a vector for gene silencing in barley roots and in B. distachyon leaves and possibly roots, opening up possibilities for using VIGS to study cereal root biology and to exploit the wealth of genome information in the new cereal model plant B. distachyon. On the other hand, the silencing induced by BSMV in oat seemed too

  14. Transgene-induced silencing of the zoosporogenesis-specific NIFC gene cluster of Phytophthora infestans involves chromatin alterations.

    Science.gov (United States)

    Judelson, Howard S; Tani, Shuji

    2007-07-01

    Clustered within the genome of the oomycete phytopathogen Phytophthora infestans are four genes encoding spore-specific nuclear LIM interactor-interacting factors (NIF proteins, a type of transcriptional regulator) that are moderately conserved in DNA sequence. NIFC1, NIFC2, and NIFC3 are zoosporogenesis-induced and grouped within 4 kb, and 20 kb away resides a sporulation-induced form, NIFS. To test the function of the NIFC family, plasmids expressing full-length hairpin constructs of NIFC1 or NIFC2 were stably transformed into P. infestans. This triggered silencing of the cognate gene in about one-third of transformants, and all three NIFC genes were usually cosilenced. However, NIFS escaped silencing despite its high sequence similarity to the NIFC genes. Silencing of the three NIFC genes impaired zoospore cyst germination by 60% but did not affect other aspects of the life cycle. Silencing was transcriptional based on nuclear run-on assays and associated with tighter chromatin packing based on nuclease accessibility experiments. The chromatin alterations extended a few hundred nucleotides beyond the boundaries of the transcribed region of the NIFC cluster and were not associated with increased DNA methylation. A plasmid expressing a short hairpin RNA having sequence similarity only to NIFC1 silenced both that gene and an adjacent member of the gene cluster, likely due to the expansion of a heterochromatic domain from the targeted locus. These data help illuminate the mechanism of silencing in Phytophthora and suggest that caution should be used when interpreting silencing experiments involving closely spaced genes.

  15. In Silico Identification of MicroRNAs with B/CYDV Gene Silencing Potential

    Directory of Open Access Journals (Sweden)

    Maryem Bouallègue

    Full Text Available ABSTRACT Computational investigation of a set of publicly available plant microRNAs revealed 19 barley- and other plants-encoded miRNAs and their near-complement reverse sequences (miRNA* that have potential to bind all B/CYDV open reading frames (ORFs except ORF0 and ORF6. These miRNAs/miRNAs*, their binding positions and targets are discussed in the context of biological protection of cereals against B/CYDV, based on antiviral silencing.

  16. Post-transcriptional gene silencing of the p23 silencing suppressor of Citrus tristeza virus confers resistance to the virus in transgenic Mexican lime.

    Science.gov (United States)

    Fagoaga, Carmen; López, Carmelo; de Mendoza, Alfonso Hermoso; Moreno, Pedro; Navarro, Luis; Flores, Ricardo; Peña, Leandro

    2006-01-01

    Previously, we have shown that most Mexican limes (Citrus aurantifolia (Christ.) Swing.) expressing the p23 gene of Citrus tristeza virus (CTV) exhibit aberrations resembling viral leaf symptoms. Here we report that five independent transgenic lines having normal phenotype displayed characteristics typical of post-transcriptional gene silencing (PTGS): multiple copies of the transgene, low levels of the corresponding mRNA, methylation of the silenced transgene, and accumulation of p23-specific small interfering RNAs (siRNAs). When graft- or aphid-inoculated with CTV, some propagations of these silenced lines were immune: they neither expressed symptoms nor accumulated virions and viral RNA as estimated by DAS-ELISA and Northern blot hybridization, respectively. Other propagations were moderately resistant because they became infected later and showed attenuated symptoms compared to controls. The susceptible propagations, in addition to symptom expression and elevated virus titer, accumulated p23-specific siRNAs at levels significantly higher than immune or non-inoculated propagations, and showed transgene demethylation. This variable response among clonal transformants indicates that factors other than the genetic background of the transgenic plants play a key role in PTGS-mediated resistance.

  17. Silencing of Inducible Immunoproteasome Subunit Expression by Chemically Modified siRNA and shRNA.

    Science.gov (United States)

    Gvozdeva, Olga V; Prassolov, Vladimir S; Zenkova, Marina A; Vlassov, Valentin V; Chernolovskaya, Elena L

    2016-08-01

    Overexpression of inducible subunits of immunoproteasome is related to pathogenesis of some chronic diseases. Specific inhibition of the immunosubunits may be used for the treatment of these diseases and RNA interference is one of the potent methods used in this area. We designed 2'-O-methyl modified siRNAs with selectively protected nuclease-sensitive sites, which efficiently silence LMP2, LMP7, and MECL-1 genes expression. To provide stable long-lasting inhibition of target genes, short-hairpin RNAs (shRNA) expressed by lentiviral vectors were constructed. Our results demonstrated that chemically modified siRNAs inhibited the expression of target genes with similar efficiency or with efficiency exceeding that of corresponding shRNAs and provide silencing effect for 5 days.

  18. Mechanisms guiding Polycomb activities during gene silencing in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Chongsheng eHe

    2013-11-01

    Full Text Available Polycomb group (PcG proteins act in an evolutionarily conserved epigenetic pathway that regulates chromatin structures in plants and animals, repressing many developmentally important genes by modifying histones. PcG proteins can form at least two multiprotein complexes: Polycomb repressive complexes 1 and 2 (PRC1 and PRC2, respectively. The functions of Arabidopsis thaliana PRCs have been characterized in multiple stages of development and have diverse roles in response to environmental stimuli. Recently, the mechanism that precisely regulates Arabidopsis PcG activity was extensively studied. In this review, we summarize recent discoveries in the regulations of PcG at the three different layers: the recruitment of PRCs to specific target loci, the polyubiquitination and degradation of PRC2, and the antagonism of PRC2 activity by the Trithorax group proteins. Current knowledge indicates that the powerful activity of the PcG pathway is strictly controlled for specific silencing of target genes during plant development and in response to environmental stimuli.

  19. Analysis of Silences in“The Dumb Waiter”

    Institute of Scientific and Technical Information of China (English)

    张晓莉

    2013-01-01

    Harold Pinter is one of the famous absurdist play writer in England. His works and language are full of absurd color, which is the focus of critics. Silence is a trademark of Harold Pinter’s writing. He uses it to an exquisite manner that he forms his individual“Pinteresque”silence. Silences in his play appear many times and act as a natural barrier for true self. This paper will take Pinter’s early work“The Dumb Waiter”for example to analysis the wide usage of silences in the play. The paper tries to un-mask the truth under silences. And by exploring the two types of silences, we can see characters ’true emotion and intention un-derground.

  20. Is our knowledge of voice and silence in organizations growing?

    DEFF Research Database (Denmark)

    Knoll, Michael; Wegge, Jürgen; Unterrainer, Christine

    2016-01-01

    This article has three objectives. Firstly, we seek to demonstrate the relevance of voice and silence – that is, whether employees contribute or withhold information, ideas, views and/or concerns at work – for the sustainable development of individuals, organizations and societies. Our second...... objective is to identify emerging (and enduring) issues – conceptual, theoretical and methodological – that have not yet been adequately addressed in voice and silence research. These issues include the relationship between voice and silence, how they may manifest in organizations, their manifold...... integrative approach to the nature of silence and voice and their antecedents and consequences. These opportunities include a multi-level model specifying elements and processes leading to individual and collective voice and silence, approaches to voice and silence that have received little attention...

  1. Conceiving silence: infertility as discursive contradiction in Ireland.

    Science.gov (United States)

    Allison, Jill

    2011-03-01

    This article examines the production and reproduction of silence around infertility in Ireland. Based on narratives collected during 18 months of fieldwork, this article locates the contradictory role of silence in both the private experiences of individuals faced with a difficulty conceiving and in institutions constituted as mechanisms of public support. For many people who experience infertility, silence is rooted in the social stigma associated with reproductive failure or sexual inadequacy. Silence protects privacy while at the same time foreclosing both challenges to assumptions that fertility is the norm and any counterdiscourse to the heteronormative, profamily society in Ireland. I show how the reproduction of silence about infertility is a legacy of Ireland's history, reproductive politics, and the cultural idiom of choice. I argue that support networks and Internet bulletin boards on websites create opportunities to dialogue in silence, reproducing isolation rather than creating public discourse.

  2. Manipulation of DET1 expression in tomato results in photomorphogenic phenotypes caused by post-transcriptional gene silencing

    Science.gov (United States)

    Davuluri, Ganga Rao; van Tuinen, Ageeth; Mustilli, Anna Chiara; Manfredonia, Alessandro; Newman, Robert; Burgess, Diane; Brummell, David A.; King, Stephen R.; Palys, Joe; Uhlig, John; Pennings, Henk M. J.; Bowler, Chris

    2013-01-01

    Summary The tomato HIGH PIGMENT-2 gene encodes an orthologue of the Arabidopsis nuclear protein DE-ETIOLATED 1 (DET1). From genetic analyses it has been proposed that DET1 is a negative regulator of light signal transduction, and recent results indicate that it may control light-regulated gene expression at the level of chromatin remodelling. To gain further understanding about the function of DET1 during plant development, we generated a range of overexpression constructs and introduced them into tomato. Unexpectedly, we only observed phenotypes characteristic of DET1 inactivation, i.e. hyper-responsiveness to light. Molecular analysis indicated in all cases that these phenotypes were a result of suppression of endogenous DET1 expression, due to post-transcriptional gene silencing. DET1 silencing was often lethal when it occurred at relatively early stages of plant development, whereas light hyper-responsive phenotypes were obtained when silencing occurred later on. The appearance of phenotypes correlated with the generation of siRNAs but not DNA hypermethylation, and was most efficient when using constructs with mutations in the DET1 coding sequence or with constructs containing only the 3′-terminal portion of the gene. These results indicate an important function for DET1 throughout plant development and demonstrate that silencing of DET1 in fruits results in increased carotenoids, which may have biotechnological potential. PMID:15469492

  3. Host-Induced Gene Silencing of Rice Blast Fungus Magnaporthe oryzae Pathogenicity Genes Mediated by the Brome Mosaic Virus.

    Science.gov (United States)

    Zhu, Lin; Zhu, Jian; Liu, Zhixue; Wang, Zhengyi; Zhou, Cheng; Wang, Hong

    2017-09-26

    Magnaportheoryzae is a devastating plant pathogen, which has a detrimental impact on rice production worldwide. Despite its agronomical importance, some newly-emerging pathotypes often overcome race-specific disease resistance rapidly. It is thus desirable to develop a novel strategy for the long-lasting resistance of rice plants to ever-changing fungal pathogens. Brome mosaic virus (BMV)-induced RNA interference (RNAi) has emerged as a useful tool to study host-resistance genes for rice blast protection. Planta-generated silencing of targeted genes inside biotrophic pathogens can be achieved by expression of M.oryzae-derived gene fragments in the BMV-mediated gene silencing system, a technique termed host-induced gene silencing (HIGS). In this study, the effectiveness of BMV-mediated HIGS in M.oryzae was examined by targeting three predicted pathogenicity genes, MoABC1,MoMAC1 and MoPMK1. Systemic generation of fungal gene-specific small interfering RNA (siRNA) molecules induced by inoculation of BMV viral vectors inhibited disease development and reduced the transcription of targeted fungal genes after subsequent M.oryzae inoculation. Combined introduction of fungal gene sequences in sense and antisense orientation mediated by the BMV silencing vectors significantly enhanced the efficiency of this host-generated trans-specific RNAi, implying that these fungal genes played crucial roles in pathogenicity. Collectively, our results indicated that BMV-HIGS system was a great strategy for protecting host plants against the invasion of pathogenic fungi.

  4. Electrical silencing of PDF neurons advances the phase of non-PDF clock neurons in Drosophila.

    Science.gov (United States)

    Wu, Ying; Cao, Guan; Nitabach, Michael N

    2008-04-01

    Drosophila clock neurons exhibit self-sustaining cellular oscillations that rely in part on rhythmic transcriptional feedback loops. We have previously determined that electrical silencing of the pigment dispersing factor (PDF)-expressing lateral-ventral (LN(V)) pacemaker subset of fly clock neurons via expression of an inward-rectifier K(+) channel (Kir2.1) severely disrupts free-running rhythms of locomotor activity-most flies are arrhythmic and those that are not exhibit weak short-period rhythms-and abolishes LN(V) molecular oscillation in constant darkness. PDF is known to be an important LN(V) output signal. Here we examine the effects of electrical silencing of the LN(V) pacemakers on molecular rhythms in other, nonsilenced, subsets of clock neurons. In contrast to previously described cell-autonomous abolition of free-running molecular rhythms, we find that electrical silencing of the LN(V) pacemakers via Kir2.1 expression does not impair molecular rhythms in LN(D), DN1, and DN2 subsets of clock neurons. However, free-running molecular rhythms in these non-LN(V) clock neurons occur with advanced phase. Electrical silencing of LN(V)s phenocopies PDF null mutation (pdf (01) ) at both behavioral and molecular levels except for the complete abolition of free-running cellular oscillation in the LN(V)s themselves. LN(V) electrically silenced or pdf 01 flies exhibit weak free-running behavioral rhythms with short period, and the molecular oscillation in non-LN(V) neurons phase advances in constant darkness. That LN( V) electrical silencing leads to the same behavioral and non-LN( V) molecular phenotypes as pdf 01 suggests that persistence of LN(V) molecular oscillation in pdf 01 flies has no functional effect, either on behavioral rhythms or on non-LN(V) molecular rhythms. We thus conclude that functionally relevant signals from LN(V)s to non-LN(V) clock neurons and other downstream targets rely both on PDF signaling and LN(V) electrical activity, and that LN( V

  5. Arabidopsis HDA6 Regulates Locus-Directed Heterochromatin Silencing in Cooperation with MET1

    Science.gov (United States)

    Matsui, Akihiro; Kurihara, Yukio; Morosawa, Taeko; Ishida, Junko; Tanaka, Maho; Endo, Takaho; Kakutani, Tetsuji; Toyoda, Tetsuro; Kimura, Hiroshi; Yokoyama, Shigeyuki; Shinozaki, Kazuo; Seki, Motoaki

    2011-01-01

    Heterochromatin silencing is pivotal for genome stability in eukaryotes. In Arabidopsis, a plant-specific mechanism called RNA–directed DNA methylation (RdDM) is involved in heterochromatin silencing. Histone deacetylase HDA6 has been identified as a component of such machineries; however, its endogenous targets and the silencing mechanisms have not been analyzed globally. In this study, we investigated the silencing mechanism mediated by HDA6. Genome-wide transcript profiling revealed that the loci silenced by HDA6 carried sequences corresponding to the RDR2-dependent 24-nt siRNAs, however their transcript levels were mostly unaffected in the rdr2 mutant. Strikingly, we observed significant overlap of genes silenced by HDA6 to those by the CG DNA methyltransferase MET1. Furthermore, regardless of dependence on RdDM pathway, HDA6 deficiency resulted in loss of heterochromatic epigenetic marks and aberrant enrichment for euchromatic marks at HDA6 direct targets, along with ectopic expression of these loci. Acetylation levels increased significantly in the hda6 mutant at all of the lysine residues in the H3 and H4 N-tails, except H4K16. Interestingly, we observed two different CG methylation statuses in the hda6 mutant. CG methylation was sustained in the hda6 mutant at some HDA6 target loci that were surrounded by flanking DNA–methylated regions. In contrast, complete loss of CG methylation occurred in the hda6 mutant at the HDA6 target loci that were isolated from flanking DNA methylation. Regardless of CG methylation status, CHG and CHH methylation were lost and transcriptional derepression occurred in the hda6 mutant. Furthermore, we show that HDA6 binds only to its target loci, not the flanking methylated DNA, indicating the profound target specificity of HDA6. We propose that HDA6 regulates locus-directed heterochromatin silencing in cooperation with MET1, possibly recruiting MET1 to specific loci, thus forming the foundation of silent chromatin structure

  6. Functional validation of a constitutive autonomous silencer element.

    Directory of Open Access Journals (Sweden)

    Heyuan Qi

    Full Text Available Sequences of the genome that are capable of silencing gene expression are thought to play a key role in gene regulation. However, very few silencer elements capable of functioning in mammalian cells have been described, and only a fraction of these have been tested for the ability to function in an autonomous fashion. We report here the characterization and functional validation of a constitutive autonomous silencer element from the human genome called T39, and the comparison of T39 to three other putative silencer elements previously described by others. Functional analysis included one assay for enhancer-blocking insulator activity and two independent assays for silencer activity, all based on stable transfection and comparison to a neutral spacer control. In erythroid K562 cells, T39 exhibited potent silencer activity, the previously described element PRE2-S5 exhibited modest silencer activity, and the two other previously described elements exhibited no silencer activity. T39 was further found to be capable of silencing three disparate promoters, of silencing gene expression in three disparate cell lines, and of functioning as a single copy in a topology-independent manner. Of the four elements analyzed, only T39 exhibits a constitutive pattern of DNase hypersensitivity and binding by CTCF. In its native location the T39 element also exhibits a unique interaction profile with a subset of distal putative regulatory elements. Taken together, these studies validate T39 as a constitutive autonomous silencer, identify T39 as a defined control for future studies of other regulatory elements such as insulators, and provide a basic chromatin profile for one highly potent silencer element.

  7. Speaking of Silence: Comments from an Irish Studies Perspective

    OpenAIRE

    McQuaid, Sara Dybris; Beville, Maria

    2012-01-01

    This paper will discuss how silence continues to prove a forbearing presence in literary, historical, cultural and political discourse in Ireland, North and South. It will suggest that not only does Ireland prove a useful topic for understanding the many implications of silence, it will further argue that silence in its own right is a unique and important route to understanding the complexities of modern Ireland in cultural, contemporary and historical terms. This is true, not least in the ca...

  8. DNA elements reducing transcriptional gene silencing revealed by a novel screening strategy.

    Directory of Open Access Journals (Sweden)

    Naoki Kishimoto

    Full Text Available Transcriptional gene silencing (TGS--a phenomenon observed in endogenous genes/transgenes in eukaryotes--is a huge hindrance to transgenic technology and occurs mainly when the genes involved share sequence homology in their promoter regions. TGS depends on chromosomal position, suggesting the existence of genomic elements that suppress TGS. However, no systematic approach to identify such DNA elements has yet been reported. Here, we developed a successful novel screening strategy to identify such elements (anti-silencing regions-ASRs, based on their ability to protect a flanked transgene from TGS. A silenced transgenic tobacco plant in which a subsequently introduced transgene undergoes obligatory promoter-homology dependent TGS in trans allowed the ability of DNA elements to prevent TGS to be used as the screening criterion. We also identified ASRs in a genomic library from a different plant species (Lotus japonicus: a perennial legume; the ASRs include portions of Ty1/copia retrotransposon-like and pararetrovirus-like sequences; the retrotransposon-like sequences also showed interspecies anti-TGS activity in a TGS-induction system in Arabidopsis. Anti-TGS elements could provide effective tools to reduce TGS and ensure proper regulation of transgene expression. Furthermore, the screening strategy described here will also facilitate the efficient identification of new classes of anti-TGS elements.

  9. Soilborne wheat mosaic virus (SBWMV 19K protein belongs to a class of cysteine rich proteins that suppress RNA silencing

    Directory of Open Access Journals (Sweden)

    Howard Amanda

    2005-03-01

    Full Text Available Abstract Amino acid sequence analyses indicate that the Soilborne wheat mosaic virus (SBWMV 19K protein is a cysteine-rich protein (CRP and shares sequence homology with CRPs derived from furo-, hordei-, peclu- and tobraviruses. Since the hordei- and pecluvirus CRPs were shown to be pathogenesis factors and/or suppressors of RNA silencing, experiments were conducted to determine if the SBWMV 19K CRP has similar activities. The SBWMV 19K CRP was introduced into the Potato virus X (PVX viral vector and inoculated to tobacco plants. The SBWMV 19K CRP aggravated PVX-induced symptoms and restored green fluorescent protein (GFP expression to GFP silenced tissues. These observations indicate that the SBWMV 19K CRP is a pathogenicity determinant and a suppressor of RNA silencing.

  10. The 7a accessory protein of severe acute respiratory syndrome coronavirus acts as an RNA silencing suppressor.

    Science.gov (United States)

    Karjee, Sumona; Minhas, Ankita; Sood, Vikas; Ponia, Sanket S; Banerjea, Akhil C; Chow, Vincent T K; Mukherjee, Sunil K; Lal, Sunil K

    2010-10-01

    RNA silencing suppressors (RSSs) are well studied for plant viruses but are not well defined to date for animal viruses. Here, we have identified an RSS from a medically important positive-sense mammalian virus, Severe acute respiratory syndrome coronavirus. The viral 7a accessory protein suppressed both transgene and virus-induced gene silencing by reducing the levels of small interfering RNA (siRNA). The suppression of silencing was analyzed by two independent assays, and the middle region (amino acids [aa] 32 to 89) of 7a was responsible for suppression. Finally, the RNA suppression property and the enhancement of heterologous replicon activity by the 7a protein were confirmed for animal cell lines.

  11. RNA interference as a gene silencing tool to control Tuta absoluta in tomato (Solanum lycopersicum

    Directory of Open Access Journals (Sweden)

    Roberto A. Camargo

    2016-12-01

    Full Text Available RNA interference (RNAi, a gene-silencing mechanism that involves providing double-stranded RNA molecules that match a specific target gene sequence, is now widely used in functional genetic studies. The potential application of RNAi-mediated control of agricultural insect pests has rapidly become evident. The production of transgenic plants expressing dsRNA molecules that target essential insect genes could provide a means of specific gene silencing in larvae that feed on these plants, resulting in larval phenotypes that range from loss of appetite to death. In this report, we show that the tomato leafminer (Tuta absoluta, a major threat to commercial tomato production, can be targeted by RNAi. We selected two target genes (Vacuolar ATPase-A and Arginine kinase based on the RNAi response reported for these genes in other pest species. In view of the lack of an artificial diet for T. absoluta, we used two approaches to deliver dsRNA into tomato leaflets. The first approach was based on the uptake of dsRNA by leaflets and the second was based on “in planta-induced transient gene silencing” (PITGS, a well-established method for silencing plant genes, used here for the first time to deliver in planta-transcribed dsRNA to target insect genes. Tuta absoluta larvae that fed on leaves containing dsRNA of the target genes showed an ∼60% reduction in target gene transcript accumulation, an increase in larval mortality and less leaf damage. We then generated transgenic ‘Micro-Tom’ tomato plants that expressed hairpin sequences for both genes and observed a reduction in foliar damage by T. absoluta in these plants. Our results demonstrate the feasibility of RNAi as an alternative method for controlling this critical tomato pest.

  12. Piecewise Silence in Discrete Cosmological Models

    CERN Document Server

    Clifton, Timothy; Rosquist, Kjell

    2014-01-01

    We consider a family of cosmological models in which all mass is confined to a regular lattice of identical black holes. By exploiting the reflection symmetry about planes that bisect these lattices into identical halves, we are able to consider the evolution of a number of geometrically distinguished surfaces that exist within each of them. We show that gravitational waves are effectively trapped within small chambers for all time, and are not free to propagate throughout the space-time. Each chamber therefore evolves as if it were in isolation from the rest of the universe. We call this phenomenon "piecewise silence".

  13. The cricket paralysis virus suppressor inhibits microRNA silencing mediated by the Drosophila Argonaute-2 protein.

    Directory of Open Access Journals (Sweden)

    Corinne Besnard-Guérin

    Full Text Available Small RNAs are potent regulators of gene expression. They also act in defense pathways against invading nucleic acids such as transposable elements or viruses. To counteract these defenses, viruses have evolved viral suppressors of RNA silencing (VSRs. Plant viruses encoded VSRs interfere with siRNAs or miRNAs by targeting common mediators of these two pathways. In contrast, VSRs identified in insect viruses to date only interfere with the siRNA pathway whose effector Argonaute protein is Argonaute-2 (Ago-2. Although a majority of Drosophila miRNAs exerts their silencing activity through their loading into the Argonaute-1 protein, recent studies highlighted that a fraction of miRNAs can be loaded into Ago-2, thus acting as siRNAs. In light of these recent findings, we re-examined the role of insect VSRs on Ago-2-mediated miRNA silencing in Drosophila melanogaster. Using specific reporter systems in cultured Schneider-2 cells and transgenic flies, we showed here that the Cricket Paralysis virus VSR CrPV1-A but not the Flock House virus B2 VSR abolishes silencing by miRNAs loaded into the Ago-2 protein. Thus, our results provide the first evidence that insect VSR have the potential to directly interfere with the miRNA silencing pathway.

  14. Silencing the SpMPK1, SpMPK2, and SpMPK3 Genes in Tomato Reduces Abscisic Acid—Mediated Drought Tolerance

    Directory of Open Access Journals (Sweden)

    Yan Liang

    2013-11-01

    Full Text Available Drought is a major threat to agriculture production worldwide. Mitogen-activated protein kinases (MAPKs play a pivotal role in sensing and converting stress signals into appropriate responses so that plants can adapt and survive. To examine the function of MAPKs in the drought tolerance of tomato plants, we silenced the SpMPK1, SpMPK2, and SpMPK3 genes in wild-type plants using the virus-induced gene silencing (VIGS method. The results indicate that silencing the individual genes or co-silencing SpMPK1, SpMPK2, and SpMPK3 reduced the drought tolerance of tomato plants by varying degrees. Co-silencing SpMPK1 and SpMPK2 impaired abscisic acid (ABA-induced and hydrogen peroxide (H2O2-induced stomatal closure and enhanced ABA-induced H2O2 production. Similar results were observed when silencing SpMPK3 alone, but not when SpMPK1 and SpMPK2 were individually silenced. These data suggest that the functions of SpMPK1 and SpMPK2 are redundant, and they overlap with that of SpMPK3 in drought stress signaling pathways. In addition, we found that SpMPK3 may regulate H2O2 levels by mediating the expression of CAT1. Hence, SpMPK1, SpMPK2, and SpMPK3 may play crucial roles in enhancing tomato plants’ drought tolerance by influencing stomatal activity and H2O2 production via the ABA-H2O2 pathway.

  15. Enhanced transgene expression in sugarcane by co-expression of virus-encoded RNA silencing suppressors.

    Directory of Open Access Journals (Sweden)

    San-Ji Gao

    Full Text Available Post-transcriptional gene silencing is commonly observed in polyploid species and often poses a major limitation to plant improvement via biotechnology. Five plant viral suppressors of RNA silencing were evaluated for their ability to counteract gene silencing and enhance the expression of the Enhanced Yellow Fluorescent Protein (EYFP or the β-glucuronidase (GUS reporter gene in sugarcane, a major sugar and biomass producing polyploid. Functionality of these suppressors was first verified in Nicotiana benthamiana and onion epidermal cells, and later tested by transient expression in sugarcane young leaf segments and protoplasts. In young leaf segments co-expressing a suppressor, EYFP reached its maximum expression at 48-96 h post-DNA introduction and maintained its peak expression for a longer time compared with that in the absence of a suppressor. Among the five suppressors, Tomato bushy stunt virus-encoded P19 and Barley stripe mosaic virus-encoded γb were the most efficient. Co-expression with P19 and γb enhanced EYFP expression 4.6-fold and 3.6-fold in young leaf segments, and GUS activity 2.3-fold and 2.4-fold in protoplasts compared with those in the absence of a suppressor, respectively. In transgenic sugarcane, co-expression of GUS and P19 suppressor showed the highest accumulation of GUS levels with an average of 2.7-fold more than when GUS was expressed alone, with no detrimental phenotypic effects. The two established transient expression assays, based on young leaf segments and protoplasts, and confirmed by stable transgene expression, offer a rapid versatile system to verify the efficiency of RNA silencing suppressors that proved to be valuable in enhancing and stabilizing transgene expression in sugarcane.

  16. Silencing of cryptic prophages in Corynebacterium glutamicum.

    Science.gov (United States)

    Pfeifer, Eugen; Hünnefeld, Max; Popa, Ovidiu; Polen, Tino; Kohlheyer, Dietrich; Baumgart, Meike; Frunzke, Julia

    2016-12-01

    DNA of viral origin represents a ubiquitous element of bacterial genomes. Its integration into host regulatory circuits is a pivotal driver of microbial evolution but requires the stringent regulation of phage gene activity. In this study, we describe the nucleoid-associated protein CgpS, which represents an essential protein functioning as a xenogeneic silencer in the Gram-positive Corynebacterium glutamicum CgpS is encoded by the cryptic prophage CGP3 of the C. glutamicum strain ATCC 13032 and was first identified by DNA affinity chromatography using an early phage promoter of CGP3. Genome-wide profiling of CgpS binding using chromatin affinity purification and sequencing (ChAP-Seq) revealed its association with AT-rich DNA elements, including the entire CGP3 prophage region (187 kbp), as well as several other elements acquired by horizontal gene transfer. Countersilencing of CgpS resulted in a significantly increased induction frequency of the CGP3 prophage. In contrast, a strain lacking the CGP3 prophage was not affected and displayed stable growth. In a bioinformatics approach, cgpS orthologs were identified primarily in actinobacterial genomes as well as several phage and prophage genomes. Sequence analysis of 618 orthologous proteins revealed a strong conservation of the secondary structure, supporting an ancient function of these xenogeneic silencers in phage-host interaction.

  17. Organizational Silence in Universities as the Predictor of Organizational Culture

    Directory of Open Access Journals (Sweden)

    Erkan YAMAN

    2014-04-01

    Full Text Available The aim of this study is to determine the relationship between the sense of organizational silence and the organizational culture the instructors perceived. In this study, the scale for determining organizational culture developed by İpek (1999 and the scale for measuring organizational silence developed by Çakıcı (2007 and adapted by Soycan (2010 are used. No remarkable difference was found in the academic staff's sense of organizational silence degree according to their genders and educational backgrounds. It was seen that the instructors' sense of organizational silence had remarkable differences according to their age group, faculty, sense of administration type in their institutions, frequency of their face-to-face communication with their administrators and their thoughts of speaking clearly with their administrators. It was observed that research assistants had a significantly higher sense of organizational silence than the lecturers in the sense of ‘Lack of Experience'. It was seen that academicians who had 1-5 years of employment period had the highest sense of organizational silence while those who had 21 years or more employment period had the lowest sense of organizational silence in the sense of ‘Lack of Experience' of organizational silence. When the points that participant academicians got from organizational silence and organizational culture scales analyzed in the correlation table, it was found out that there was a remarkable relationship between the academicians' sense of organizational silence and sense of organizational culture. This relationship was a medium-level negative relationship between subdimensions of two scales. A medium-level negative relationship between the organizational silence (total and the organizational culture was also seen. Based on the findings, university administrators were proposed to create a participant culture in their institutions as well as to encourage instructors to speak clearly and

  18. Short interfering RNA-mediated knockdown of drosha and pasha in undifferentiated Meloidogyne incognita eggs leads to irregular growth and embryonic lethality.

    Science.gov (United States)

    Dalzell, Johnathan J; Warnock, Neil D; Stevenson, Michael A; Mousley, Angela; Fleming, Colin C; Maule, Aaron G

    2010-09-01

    Micro-(mi)RNAs play a pivotal role in the developmental regulation of plants and animals. We reasoned that disruption of normal heterochronic activity in differentiating Meloidogyne incognita eggs may lead to irregular development, lethality and by extension, represent a novel target for parasite control. On silencing the nuclear RNase III enzyme drosha, a critical effector of miRNA maturation in animals, we found a significant inhibition of normal development and hatching in short interfering (si)RNA-soaked M. incognita eggs. Developing juveniles presented with highly irregular tissue patterning within the egg, and we found that unlike our previous gene silencing efforts focused on FMRFamide (Phe-Met-Arg-Phe-NH(2))-like peptides (FLPs), there was no observable phenotypic recovery following removal of the environmental siRNA. Aberrant phenotypes were exacerbated over time, and drosha knockdown proved embryonically lethal. Subsequently, we identified and silenced the drosha cofactor pasha, revealing a comparable inhibition of normal embryonic development within the eggs to that of drosha-silenced eggs, eventually leading to embryonic lethality. To further probe the link between normal embryonic development and the M. incognita RNA interference (RNAi) pathway, we attempted to examine the impact of silencing the cytosolic RNase III enzyme dicer. Unexpectedly, we found a substantial up-regulation of dicer transcript abundance, which did not impact on egg differentiation or hatching rates. Silencing of the individual transcripts in hatched J2s was significantly less successful and resulted in temporary phenotypic aberration of the J2s, which recovered within 24h to normal movement and posture on washing out the siRNA. Soaking the J2s in dicer siRNA resulted in a modest decrease in dicer transcript abundance which had no observable impact on phenotype or behaviour within 48h of initial exposure to siRNA. We propose that drosha, pasha and their ancillary factors may

  19. Silencing of TaBTF3 gene impairs tolerance to freezing and drought stresses in wheat.

    Science.gov (United States)

    Kang, Guozhang; Ma, Hongzhen; Liu, Guoqin; Han, Qiaoxia; Li, Chengwei; Guo, Tiancai

    2013-11-01

    Basic transcription factor 3 (BTF3), the β-subunit of the nascent polypeptide-associated complex, is responsible for the transcriptional initiation of RNA polymerase II and is also involved in cell apoptosis, translation initiation regulation, growth, development, and other functions. Here, we report the impact of BTF3 on abiotic tolerance in higher plants. The transcription levels of the TaBTF3 gene, first isolated from wheat seedlings in our lab, were differentially regulated by diverse abiotic stresses and hormone treatments, including PEG-induced stress (20 % polyethylene glycol 6000), cold (4 °C), salt (100 mM NaCl), abscisic acid (100 μM), methyl jasmonate (50 μM), and salicylic acid (50 μM). Southern blot analysis indicated that, in the wheat genome, TaBTF3 is a multi-copy gene. Compared to BSMV-GFP-infected wheat plants (control), under freezing (-8 °C for 48 h) or drought stress (withholding water for 15 days) conditions, TaBTF3-silenced wheat plants showed lower survival rates, free proline content, and relative water content and higher relative electrical conductivity and water loss rate. These results suggest that silencing of the TaBTF3 gene may impair tolerance to freezing and drought stresses in wheat and that it may be involved in the response to abiotic stresses in higher plants.

  20. The Educators' Guide to the Day of Silence

    Science.gov (United States)

    Gay, Lesbian and Straight Education Network (GLSEN), 2010

    2010-01-01

    The Day of Silence is the largest single student-led action towards creating safer schools for all, regardless of sexual orientation, gender identity or gender expression. From the first-ever Day of Silence at the University of Virginia in 1996, to the organizing efforts in over 8,000 middle schools, high schools, colleges and universities across…

  1. The Role of Silence in Teaching and Learning

    Science.gov (United States)

    Schultz, Katherine

    2013-01-01

    The author's first teaching position was as a 4th and 5th grade teacher at a school in Philadelphia. There, she learned the Quaker value of adding silence and periods of reflection to her teaching to provide a wider range of students with the opportunity to participate in classroom discussions. Later, a focus on silence as a teaching strategy led…

  2. Silence in the Second Language Classrooms of Japanese Universities

    Science.gov (United States)

    King, Jim

    2013-01-01

    Japanese language learners' proclivity for silence has been alluded to by various writers (e.g. Anderson 1993; Korst 1997; Greer 2000) and is supported by plenty of anecdotal evidence, but large-scale, empirical studies aimed at measuring the extent of macro-level silence within Japanese university L2 classrooms are notably lacking. This article…

  3. Echoes of Silence: Empathy and Making Connections through Writing Process

    Science.gov (United States)

    Freedman, Joel M.

    2009-01-01

    On April 25, 2008, students on college and public school campuses collectively committed to a vow of silence commemorating an event known as the National Day of Silence. This student-generated, nationwide action theatrically "speaks out" in solidarity with lesbian, gay, bisexual, and transgender (LGBT) people who for one reason or another fear…

  4. Echoes of asymptotic silence in causal set quantum gravity

    Science.gov (United States)

    Eichhorn, Astrid; Mizera, Sebastian; Surya, Sumati

    2017-08-01

    We explore the idea of asymptotic silence in causal set theory and find that causal sets approximated by continuum spacetimes exhibit behavior akin to asymptotic silence. We make use of an intrinsic definition of spatial distance between causal set elements in the discrete analogue of a spatial hypersurface. Using numerical simulations for causal sets approximated by \

  5. Hearing the Silence: Acknowledging the Voice of My Latina Sisters

    Science.gov (United States)

    Martinez-Vogt, Emily

    2015-01-01

    Latina community college students experience a number of challenges during their transition to college. Findings from a larger study indicated that Latina community college students experienced racism and stereotyping on campus responding with silence. Silence occurred in two ways: (1) Latinas were forced to be silent, and/or (2) Latinas chose to…

  6. No-Big-Silence teeb klubituuri / Urmas Hännile

    Index Scriptorium Estoniae

    Hännile, Urmas

    2009-01-01

    Rockansamblist No-Big-Silence ja dark-popansamblist Sinine, nende kontsertttuurist mööda Eestimaad, tutvustamisel bändide uued albumid (No-Big-Silence "Starstealer" ja Sinine "Butterflies"), Pärnus on kontsert 24. oktoobril klubis Sugar

  7. In a Silent Way: Student Perceptions of Silence in Community

    Science.gov (United States)

    Wood, Margaret; Tribe, Robert

    2016-01-01

    This paper explores young people's perceptions of the role and value of shared "gathered" silence in the corporate life of a school community. It draws on a small-scale qualitative investigation in a Quaker school setting. There may be particular things to learn about the practice of stillness and silence inherent in the ethos of a…

  8. Reflections on the Silencing the Self Scale and Its Origins

    Science.gov (United States)

    Jack, Dana Crowley

    2011-01-01

    In this article, the author reflects on the Silencing the Self Scale (STSS) and blends her personal and professional thoughts about self-silencing, gender, and depression. For her, the despair of depression deeply involves questions of value and meaning, culture and freedom. The STSS grew from listening to depressed women's voices. From them, the…

  9. The Functions of Silence within the Context of Teacher Training.

    Science.gov (United States)

    Phillips, Diane

    1994-01-01

    This article examines the function of silence in both preservice and in-service teacher education classroom observations, workshops, and feedback sessions. Teacher educators and teacher trainees need to be aware of the effects of silence in oral and written discourse. (19 references) (MDM)

  10. Optimisation of acoustic silencer for the screw compressor system

    NARCIS (Netherlands)

    Swamy, M.; Lier, L.J. van; Smeulers, J.P.M.

    2014-01-01

    In one of the screw compressor system, designed silencer was not optimal. A great challenge was the large variation in operating conditions, especially the variation of the molecular weight of the gas. There was need to optimize the silencer. This paper describes the acoustic modelling tools to

  11. Optimisation of acoustic silencer for the screw compressor system

    NARCIS (Netherlands)

    Swamy, M.; Lier, L.J. van; Smeulers, J.P.M.

    2014-01-01

    In one of the screw compressor system, designed silencer was not optimal. A great challenge was the large variation in operating conditions, especially the variation of the molecular weight of the gas. There was need to optimize the silencer. This paper describes the acoustic modelling tools to opti

  12. An Analysis of Heathcliff’s Silence in Wuthering Heights

    Institute of Scientific and Technical Information of China (English)

    潘琛

    2013-01-01

    Heathcliff is a highly controversial character in Emily Brontë’s canon Wuthering Heights. He is depicted as an incredi-ble conglomeration of enigmas and simplicity, aloofness and affinity, ferocity and vulnerability, inhumanity and heroicity, a man who appears more silent and preoccupied than talkative and carefree, inaudible and incalculable in both words and thoughts. The author of this paper considers that there is much left to be read and contemplate on in Heathcliff ’s silence and thus make a tempa-tive research into Heathcliff’s silence by discerning its manifestations and probing its causes, in order to resonate with the inner touch of this complicated soul and relate his silence with the spirit that Emily Brontë wished to deliver through Wuthering Heights. Heathcliff’s silence manifests as muteness, elusion and colloquial or physical violence. In his whole life, Heathcliff inter-mittently experiences the self-chosen silence and the forced silence. He chooses to be silence out of self-protection and the infe-riority complex;he considers silence as a token of masculinity. And the ruthless force from outside also compels him into a periph-eralized situation where he has to keep silent and struggles against the torture and torment alone.

  13. No-Big-Silence teeb klubituuri / Urmas Hännile

    Index Scriptorium Estoniae

    Hännile, Urmas

    2009-01-01

    Rockansamblist No-Big-Silence ja dark-popansamblist Sinine, nende kontsertttuurist mööda Eestimaad, tutvustamisel bändide uued albumid (No-Big-Silence "Starstealer" ja Sinine "Butterflies"), Pärnus on kontsert 24. oktoobril klubis Sugar

  14. Nucleoporin mediated nuclear positioning and silencing of HMR.

    Directory of Open Access Journals (Sweden)

    Giulia J Ruben

    Full Text Available The organization of chromatin domains in the nucleus is an important factor in gene regulation. In eukaryotic nuclei, transcriptionally silenced chromatin clusters at the nuclear periphery while transcriptionally poised chromatin resides in the nuclear interior. Recent studies suggest that nuclear pore proteins (NUPs recruit loci to nuclear pores to aid in insulation of genes from silencing and during gene activation. We investigated the role of NUPs at a native yeast insulator and show that while NUPs localize to the native tDNA insulator adjacent to the silenced HMR domain, loss of pore proteins does not compromise insulation. Surprisingly we find that NUPs contribute to silencing at HMR and are able to restore silencing to a silencing-defective HMR allele when tethered to the locus. We show that the perinuclear positioning of heterochromatin is important for the NUP-mediated silencing effect and find that loss of NUPs result in decreased localization of HMR to the nuclear periphery. We also show that loss of telomeric tethering pathways does not eliminate NUP localization to HMR, suggesting that NUPs may mediate an independent pathway for HMR association with the nuclear periphery. We propose that localization of NUPs to the tDNA insulator at HMR helps maintain the intranuclear position of the silent locus, which in turn contributes to the fidelity of silencing at HMR.

  15. Nucleoporin mediated nuclear positioning and silencing of HMR.

    Science.gov (United States)

    Ruben, Giulia J; Kirkland, Jacob G; MacDonough, Tracy; Chen, Miao; Dubey, Rudra N; Gartenberg, Marc R; Kamakaka, Rohinton T

    2011-01-01

    The organization of chromatin domains in the nucleus is an important factor in gene regulation. In eukaryotic nuclei, transcriptionally silenced chromatin clusters at the nuclear periphery while transcriptionally poised chromatin resides in the nuclear interior. Recent studies suggest that nuclear pore proteins (NUPs) recruit loci to nuclear pores to aid in insulation of genes from silencing and during gene activation. We investigated the role of NUPs at a native yeast insulator and show that while NUPs localize to the native tDNA insulator adjacent to the silenced HMR domain, loss of pore proteins does not compromise insulation. Surprisingly we find that NUPs contribute to silencing at HMR and are able to restore silencing to a silencing-defective HMR allele when tethered to the locus. We show that the perinuclear positioning of heterochromatin is important for the NUP-mediated silencing effect and find that loss of NUPs result in decreased localization of HMR to the nuclear periphery. We also show that loss of telomeric tethering pathways does not eliminate NUP localization to HMR, suggesting that NUPs may mediate an independent pathway for HMR association with the nuclear periphery. We propose that localization of NUPs to the tDNA insulator at HMR helps maintain the intranuclear position of the silent locus, which in turn contributes to the fidelity of silencing at HMR.

  16. Silence in the Second Language Classrooms of Japanese Universities

    Science.gov (United States)

    King, Jim

    2013-01-01

    Japanese language learners' proclivity for silence has been alluded to by various writers (e.g. Anderson 1993; Korst 1997; Greer 2000) and is supported by plenty of anecdotal evidence, but large-scale, empirical studies aimed at measuring the extent of macro-level silence within Japanese university L2 classrooms are notably lacking. This article…

  17. Speaking of Silence: Comments from an Irish Studies Perspective

    DEFF Research Database (Denmark)

    McQuaid, Sara Dybris; Beville, Maria

    2012-01-01

    This paper will discuss how silence continues to prove a forbearing presence in literary, historical, cultural and political discourse in Ireland, North and South. It will suggest that not only does Ireland prove a useful topic for understanding the many implications of silence, it will further a...

  18. Silence: A Rhetorical Art for Resisting Discipline(s).

    Science.gov (United States)

    Glenn, Cheryl

    2002-01-01

    Argues that silence can be a specifically feminist rhetorical art, often one of resistance. Draws on two key rhetorical movements: the Anita Hill-Clarence Thomas hearings and the never-heard hearing of Lani Guinier. Explores the rhetorical dimensions of silence as a feminist position that can resist disciplinary pigeon-holing, embrace political…

  19. Regulation of the fetal hemoglobin silencing factor BCL11A

    Science.gov (United States)

    Basak, Anindita; Sankaran, Vijay G.

    2016-01-01

    The clinical severity of sickle cell disease and β-thalassemia, the major disorders of β-globin, can be ameliorated by increased production of fetal hemoglobin (HbF). Here, we provide a brief overview of the fetal-to-adult hemoglobin switch that occurs in humans shortly after birth and review our current understanding of one of the most potent known regulators of this switching process, the multiple zinc finger–containing transcription factor BCL11A. Originally identified in genome-wide association studies, multiple orthogonal lines of evidence have validated BCL11A as a key regulator of hemoglobin switching and as a promising therapeutic target for HbF induction. We discuss recent studies that have highlighted its importance in silencing the HbF-encoding genes and discuss opportunities that exist to further understand the regulation of BCL11A and its mechanism of action, which could provide new insight into opportunities to induce HbF for therapeutic purposes. PMID:26963603

  20. Silencing the Transcriptional Repressor, ZCT1, Illustrates the Tight Regulation of Terpenoid Indole Alkaloid Biosynthesis in Catharanthus roseus Hairy Roots.

    Science.gov (United States)

    Rizvi, Noreen F; Weaver, Jessica D; Cram, Erin J; Lee-Parsons, Carolyn W T

    2016-01-01

    The Catharanthus roseus plant is the source of many valuable terpenoid indole alkaloids (TIAs), including the anticancer compounds vinblastine and vincristine. Transcription factors (TFs) are promising metabolic engineering targets due to their ability to regulate multiple biosynthetic pathway genes. To increase TIA biosynthesis, we elicited the TIA transcriptional activators (ORCAs and other unidentified TFs) with the plant hormone, methyl jasmonate (MJ), while simultaneously silencing the expression of the transcriptional repressor ZCT1. To silence ZCT1, we developed transgenic hairy root cultures of C. roseus that expressed an estrogen-inducible Zct1 hairpin for activating RNA interference. The presence of 17β-estradiol (5μM) effectively depleted Zct1 in hairy root cultures elicited with MJ dosages that either optimize or inhibit TIA production (250 or 1000μM). However, silencing Zct1 was not sufficient to increase TIA production or the expression of the TIA biosynthetic genes (G10h, Tdc, and Str), illustrating the tight regulation of TIA biosynthesis. The repression of the TIA biosynthetic genes at the inhibitory MJ dosage does not appear to be solely regulated by ZCT1. For instance, while Zct1 and Zct2 levels decreased through activating the Zct1 hairpin, Zct3 levels remained elevated. Since ZCT repressors have redundant yet distinct functions, silencing all three ZCTs may be necessary to relieve their repression of alkaloid biosynthesis.

  1. Analysis of the siRNA-Mediated Gene Silencing Process Targeting Three Homologous Genes Controlling Soybean Seed Oil Quality.

    Directory of Open Access Journals (Sweden)

    Sha Lu

    Full Text Available In the past decade, RNA silencing has gained significant attention because of its success in genomic scale research and also in the genetic improvement of crop plants. However, little is known about the molecular basis of siRNA processing in association with its target transcript. To reveal this process for improving hpRNA-mediated gene silencing in crop plants, the soybean GmFAD3 gene family was chosen as a test model. We analyzed RNAi mutant soybean lines in which three members of the GmFAD3 gene family were silenced. The silencing levels of FAD3A, FAD3B and FAD3C were correlated with the degrees of sequence homology between the inverted repeat of hpRNA and the GmFAD3 transcripts in the RNAi lines. Strikingly, transgenes in two of the three RNAi lines were heavily methylated, leading to a dramatic reduction of hpRNA-derived siRNAs. Small RNAs corresponding to the loop portion of the hairpin transcript were detected while much lower levels of siRNAs were found outside of the target region. siRNAs generated from the 318-bp inverted repeat were found to be diced much more frequently at stem sequences close to the loop and associated with the inferred cleavage sites on the target transcripts, manifesting "hot spots". The top candidate hpRNA-derived siRNA share certain sequence features with mature miRNA. This is the first comprehensive and detailed study revealing the siRNA-mediated gene silencing mechanism in crop plants using gene family GmFAD3 as a test model.

  2. Analysis of the siRNA-Mediated Gene Silencing Process Targeting Three Homologous Genes Controlling Soybean Seed Oil Quality.

    Science.gov (United States)

    Lu, Sha; Yin, Xiaoyan; Spollen, William; Zhang, Ning; Xu, Dong; Schoelz, James; Bilyeu, Kristin; Zhang, Zhanyuan J

    2015-01-01

    In the past decade, RNA silencing has gained significant attention because of its success in genomic scale research and also in the genetic improvement of crop plants. However, little is known about the molecular basis of siRNA processing in association with its target transcript. To reveal this process for improving hpRNA-mediated gene silencing in crop plants, the soybean GmFAD3 gene family was chosen as a test model. We analyzed RNAi mutant soybean lines in which three members of the GmFAD3 gene family were silenced. The silencing levels of FAD3A, FAD3B and FAD3C were correlated with the degrees of sequence homology between the inverted repeat of hpRNA and the GmFAD3 transcripts in the RNAi lines. Strikingly, transgenes in two of the three RNAi lines were heavily methylated, leading to a dramatic reduction of hpRNA-derived siRNAs. Small RNAs corresponding to the loop portion of the hairpin transcript were detected while much lower levels of siRNAs were found outside of the target region. siRNAs generated from the 318-bp inverted repeat were found to be diced much more frequently at stem sequences close to the loop and associated with the inferred cleavage sites on the target transcripts, manifesting "hot spots". The top candidate hpRNA-derived siRNA share certain sequence features with mature miRNA. This is the first comprehensive and detailed study revealing the siRNA-mediated gene silencing mechanism in crop plants using gene family GmFAD3 as a test model.

  3. The RNA silencing pathway: the bits and pieces that matter.

    Directory of Open Access Journals (Sweden)

    Marian A C Groenenboom

    2005-07-01

    Full Text Available Cellular pathways are generally proposed on the basis of available experimental knowledge. The proposed pathways, however, may be inadequate to describe the phenomena they are supposed to explain. For instance, by means of concise mathematical models we are able to reveal shortcomings in the current description of the pathway of RNA silencing. The silencing pathway operates by cleaving siRNAs from dsRNA. siRNAs can associate with RISC, leading to the degradation of the target mRNA. We propose and analyze a few small extensions to the pathway: a siRNA degrading RNase, primed amplification of aberrant RNA pieces, and cooperation between aberrant RNA to trigger amplification. These extensions allow for a consistent explanation for various types of silencing phenomena, such as virus induced silencing, transgene and transposon induced silencing, and avoidance of self-reactivity, as well as for differences found between species groups.

  4. Chinanteco children’s silences in different classroom situations

    Directory of Open Access Journals (Sweden)

    Valeria Rebolledo Angulo

    2016-01-01

    Full Text Available This article analyzes, from an ethnographic perspective and a sociocultural framework, the construction of silences in the interaction between students and teachers in a multilingual classroom situation in an indigenous community in méxico. the analysis reveals how the silence of the chinanteco speaking children when asked to answer certain questions in class is not always due to their failure to understand spoken and written spanish that is used in class. their silences are responses taking different meanings in specific situations. the silence of the children can be a way of resisting, a way of hiding, and, sometimes, their voices are silenced.

  5. ATOX1 gene silencing increases susceptibility to anticancer therapy based on copper ionophores or chelating drugs.

    Science.gov (United States)

    Barresi, Vincenza; Spampinato, Giorgia; Musso, Nicolò; Trovato Salinaro, Angela; Rizzarelli, Enrico; Condorelli, Daniele Filippo

    2016-03-01

    Copper is a catalytic cofactor required for the normal function of many enzymes involved in fundamental biological processes but highly cytotoxic when in excess. Therefore its homeostasis and distribution is strictly regulated by a network of transporters and intracellular chaperones. ATOX1 (antioxidant protein 1) is a copper chaperone that plays a role in copper homeostasis by binding and transporting cytosolic copper to ATPase proteins in the trans-Golgi network. In the present study the Caco-2 cell line, a colon carcinoma cell line, was used as an in vitro model to evaluate if ATOX1 deficiency could affect sensitivity to experimentally induced copper dyshomeostasis. Silencing of ATOX1 increased toxicity of a short treatment with a high concentration of Cu(2+). Copper ionophores, such as 5-chloro-8-hydroxyquinoline, induced a copper-dependent cell toxicity which was significantly potentiated after ATOX1 silencing. The copper chelator TPEN (N,N,N',N'-tetrakis (2-pyridylmethyl) ethylenediamine) produced a form of cell toxicity that was reversed by the addition of Cu(2+). ATOX1 silencing increased Caco-2 cell sensitivity to TPEN toxicity. Our results suggest the possibility of a therapy with copper-chelating or ionophore drugs in subtypes of tumors showing specific alterations in ATOX1 expression.

  6. Lentiviral Vector Mediated Claudin1 Silencing Inhibits Epithelial to Mesenchymal Transition in Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Xianqi Zhao

    2015-06-01

    Full Text Available Breast cancer has a high incidence and mortality rate worldwide. Several viral vectors including lentiviral, adenoviral and adeno-associated viral vectors have been used in gene therapy for various forms of human cancer, and have shown promising effects in controlling tumor development. Claudin1 (CLDN1 is a member of the tetraspan transmembrane protein family that plays a major role in tight junctions and is associated with tumor metastasis. However, the role of CLDN1 in breast cancer is largely unexplored. In this study, we tested the therapeutic potential of silencing CLDN1 expression in two breast cancer (MDA-MB-231 and MCF7 cell lines using lentiviral vector mediated RNA interference. We found that a CLDN1 short hairpin (shRNA construct efficiently silenced CLDN1 expression in both breast cancer cell lines, and CLDN1 knockdown resulted in reduced cell proliferation, survival, migration and invasion. Furthermore, silencing CLDN1 inhibited epithelial to mesenchymal transition (EMT by upregulating the epithelial cell marker, E-cadherin, and downregulating mesenchymal markers, smooth muscle cell alpha-actin (SMA and Snai2. Our data demonstrated that lentiviral vector mediated CLDN1 RNA interference has great potential in breast cancer gene therapy by inhibiting EMT and controlling tumor cell growth.

  7. Silencing GFAP isoforms in astrocytoma cells disturbs laminin-dependent motility and cell adhesion.

    Science.gov (United States)

    Moeton, Martina; Kanski, Regina; Stassen, Oscar M J A; Sluijs, Jacqueline A; Geerts, Dirk; van Tijn, Paula; Wiche, Gerhard; van Strien, Miriam E; Hol, Elly M

    2014-07-01

    Glial fibrillary acidic protein (GFAP) is an intermediate filament protein expressed in astrocytes and neural stem cells. The GFAP gene is alternatively spliced, and expression of GFAP is highly regulated during development, on brain damage, and in neurodegenerative diseases. GFAPα is the canonical splice variant and is expressed in all GFAP-positive cells. In the human brain, the alternatively spliced transcript GFAPδ marks specialized astrocyte populations, such as subpial astrocytes and the neurogenic astrocytes in the human subventricular zone. We here show that shifting the GFAP isoform ratio in favor of GFAPδ in astrocytoma cells, by selectively silencing the canonical isoform GFAPα with short hairpin RNAs, induced a change in integrins, a decrease in plectin, and an increase in expression of the extracellular matrix component laminin. Together, this did not affect cell proliferation but resulted in a significantly decreased motility of astrocytoma cells. In contrast, a down-regulation of all GFAP isoforms led to less cell spreading, increased integrin expression, and a >100-fold difference in the adhesion of astrocytoma cells to laminin. In summary, isoform-specific silencing of GFAP revealed distinct roles of a specialized GFAP network in regulating the interaction of astrocytoma cells with the extracellular matrix through laminin.-Moeton, M., Kanski, R., Stassen, O. M. J. A., Sluijs, J. A., Geerts, D., van Tijn, P., Wiche, G., van Strien, M. E., Hol, E. M. Silencing GFAP isoforms in astrocytoma cells disturbs laminin dependent motility and cell adhesion.

  8. A dark-light transition triggers expression of the floral promoter CrFTL1 and downregulates CONSTANS-like genes in a short-day plant Chenopodium rubrum.

    Science.gov (United States)

    Drabešová, Jana; Cháb, David; Kolař, Jan; Haškovcová, Kateřina; Štorchová, Helena

    2014-05-01

    The proper timing of flowering is essential for the adaptation of plant species to their ever-changing environments. The central position in a complex regulatory network is occupied by the protein FT, which acts as a florigen. We found that light, following a permissive period of darkness, was essential to induce the floral promoter CrFTL1 and to initiate flowering in seedlings of the short-day plant Chenopodium rubrum L. We also identified two novel CONSTANS-like genes in C. rubrum and observed their rhythmic diurnal and circadian expressions. Strong rhythmicity of expression suggested that the two genes might have been involved in the regulation of photoperiod-dependent processes, despite their inability to complement co mutation in A. thaliana. The CrCOL1 and CrCOL2 genes were downregulated by dark-light transition, regardless of the length of a preceding dark period. The same treatment activated the floral promoter CrFTL1. Light therefore affected CrCOL and CrFTL1 in an opposite manner. Both CrCOL genes and CrFTL1 displayed expression patterns unique among short-day plants. Chenopodium rubrum, the subject of classical physiological studies in the past, is emerging as a useful model for the investigation of flowering at the molecular level.

  9. GENE SILENCING. Epigenetic silencing by the HUSH complex mediates position-effect variegation in human cells.

    Science.gov (United States)

    Tchasovnikarova, Iva A; Timms, Richard T; Matheson, Nicholas J; Wals, Kim; Antrobus, Robin; Göttgens, Berthold; Dougan, Gordon; Dawson, Mark A; Lehner, Paul J

    2015-06-26

    Forward genetic screens in Drosophila melanogaster for modifiers of position-effect variegation have revealed the basis of much of our understanding of heterochromatin. We took an analogous approach to identify genes required for epigenetic repression in human cells. A nonlethal forward genetic screen in near-haploid KBM7 cells identified the HUSH (human silencing hub) complex, comprising three poorly characterized proteins, TASOR, MPP8, and periphilin; this complex is absent from Drosophila but is conserved from fish to humans. Loss of HUSH components resulted in decreased H3K9me3 both at endogenous genomic loci and at retroviruses integrated into heterochromatin. Our results suggest that the HUSH complex is recruited to genomic loci rich in H3K9me3, where subsequent recruitment of the methyltransferase SETDB1 is required for further H3K9me3 deposition to maintain transcriptional silencing.

  10. Short tunnels.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1965-01-01

    Before dealing with the question of lighting short tunnels, it is necessary define what is meant by a tunnel and when it should be called 'short'. Confined to motorized road traffic the following is the most apt definition of a tunnel: every form of roofing-over a road section, irrespective of it le

  11. Alice Munro’s “Silence”: From the Politics of Silence to a Rhetoric of Silence

    OpenAIRE

    Bigot, Corinne

    2014-01-01

    Si “Silence”, qui met en scène une mère punie par le silence manipulateur de sa fille, reprend un thème présent dans de nombreuses nouvelles d’Alice Munro – le rôle et le pouvoir du silence dans les relations humaines –, c’est en réalité à une exploration particulièrement complexe du silence, aussi bien sur le plan diégétique que narratif, que la nouvelle invite. Dans “Silence”, où se joue une réverbération des silences, et qui laisse ses protagonistes dans un silence irrésolu, Alice Munro ne...

  12. The structure of an RNAi polymerase links RNA silencing and transcription.

    Directory of Open Access Journals (Sweden)

    Paula S Salgado

    2006-12-01

    Full Text Available RNA silencing refers to a group of RNA-induced gene-silencing mechanisms that developed early in the eukaryotic lineage, probably for defence against pathogens and regulation of gene expression. In plants, protozoa, fungi, and nematodes, but apparently not insects and vertebrates, it involves a cell-encoded RNA-dependent RNA polymerase (cRdRP that produces double-stranded RNA triggers from aberrant single-stranded RNA. We report the 2.3-A resolution crystal structure of QDE-1, a cRdRP from Neurospora crassa, and find that it forms a relatively compact dimeric molecule, each subunit of which comprises several domains with, at its core, a catalytic apparatus and protein fold strikingly similar to the catalytic core of the DNA-dependent RNA polymerases responsible for transcription. This evolutionary link between the two enzyme types suggests that aspects of RNA silencing in some organisms may recapitulate transcription/replication pathways functioning in the ancient RNA-based world.

  13. Rationale for developing new virus vectors to analyze gene function in grasses through virus-induced gene silencing.

    Science.gov (United States)

    Ramanna, Hema; Ding, Xin Shun; Nelson, Richard S

    2013-01-01

    The exploding availability of genome and EST-based sequences from grasses requires a technology that allows rapid functional analysis of the multitude of genes that these resources provide. There are several techniques available to determine a gene's function. For gene knockdown studies, silencing through RNAi is a powerful tool. Gene silencing can be accomplished through stable transformation or transient expression of a fragment of a target gene sequence. Stable transformation in rice, maize, and a few other species, although routine, remains a relatively low-throughput process. Transformation in other grass species is difficult and labor-intensive. Therefore, transient gene silencing methods including Agrobacterium-mediated and virus-induced gene silencing (VIGS) have great potential for researchers studying gene function in grasses. VIGS in grasses already has been used to determine the function of genes during pathogen challenge and plant development. It also can be used in moderate-throughput reverse genetics screens to determine gene function. However, the number of viruses modified to serve as silencing vectors in grasses is limited, and the silencing phenotype induced by these vectors is not optimal: the phenotype being transient and with moderate penetration throughout the tissue. Here, we review the most recent information available for VIGS in grasses and summarize the strengths and weaknesses in current virus-grass host systems. We describe ways to improve current virus vectors and the potential of other grass-infecting viruses for VIGS studies. This work is necessary because VIGS for the foreseeable future remains a higher throughput and more rapid system to evaluate gene function than stable transformation.

  14. Combination of lentivirus-mediated silencing of PPM1D and temozolomide chemotherapy eradicates malignant glioma through cell apoptosis and cell cycle arrest

    Science.gov (United States)

    Wang, Peng; Ye, Jing-An; Hou, Chong-Xian; Zhou, Dong; Zhan, Sheng-Quan

    2016-01-01

    Temozolomide (TMZ) is approved for use as first-line treatment for glioblastoma multiforme (GBM). However, GBM shows chemoresistance shortly after the initiation of treatment. In order to detect whether silencing of human protein phosphatase 1D magnesium dependent (PPM1D) gene could increase the effects of TMZ in glioma cells, glioma cells U87-MG were infected with lentiviral shRNA vector targeting PPM1D silencing. After PPM1D silencing was established, cells were treated with TMZ. The multiple functions of human glioma cells after PPM1D silencing and TMZ chemotherapy were detected by flow cytometry and MTT assay. Significantly differentially expressed genes were distinguished by microarray-based gene expression profiling and analyzed by gene pathway enrichment analysis and ontology assessment. Western blotting was used to establish the protein expression of the core genes. PPM1D gene silencing improves TMZ induced cell proliferation and induces cell apoptosis and cell cycle arrest. When PPM1D gene silencing combined with TMZ was performed in glioma cells, 367 genes were upregulated and 444 genes were downregulated compared with negative control. The most significant differential expression pathway was pathway in cancer and IGFR1R, PIK3R1, MAPK8 and EP300 are core genes in the network. Western blotting showed that MAPK8 and PIK3R1 protein expression levels were upregulated and RB1 protein expression was decreased. It was consistent with that detected in gene expression profiling. In conclusion, PPM1D gene silencing combined with TMZ eradicates glioma cells through cell apoptosis and cell cycle arrest. PIK3R1/AKT pathway plays a role in the multiple functions of glioma cells after PPM1D silencing and TMZ chemotherapy. PMID:27633132

  15. Silencing of Target Chitinase Genes via Oral Delivery of dsRNA Caused Lethal Phenotypic Effects in Mythimna separata (Lepidoptera: Noctuidae).

    Science.gov (United States)

    Cao, Budao; Bao, Wenhua; Wuriyanghan, Hada

    2017-02-01

    Mythimna separata walker (Lepidoptera: Noctuidae) is a polyphagous, migratory corn pest. Outbreak of M. separata has led to severe damage to corn production recently in China. RNAi (RNA interference) is a gene silencing technology applied both in model and non-model organisms, and it is especially useful for the latter in which the reverse genetic research tools are not available. RNAi approach was broadly investigated in many plant pathogens and was used for the generation of anti-pest transgenic plants. We are proposing to use this technology to silence M. separata endogenous genes, thereby, providing a biocontrol method for this insect. Feeding of dsRNAs for target Chitinase genes resulted in substantial decreases of their transcript levels in M. separata. Furthermore, silencing of target Chitinase genes led to phenotypic effects such as reduced body weight and increased mortality. Our study provided both reverse genetic research tool and potential control strategy for this insect species.

  16. Two virus-encoded RNA silencing suppressors, P14 of Beet necrotic yellow vein virus and S6 of Rice black streak dwarf virus

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lingdi; WANG Zhaohui; WANG Xianbing; LI Dawei; HAN Chenggui; ZHAI Yafeng; YU Jialin

    2005-01-01

    Functional analysis for gene silencing suppressor of P14 gene of Beet necrotic yellow vein virus and S6 gene of Rice black streak dwarf virus was carried out by agro- infiltration with recombinant vectors of Potato virus X. The phenotype observation of green fluorescent protein (GFP) expression and Northern blot showed that the gene silencing of gfp transgenic Nicotiana benthamiana induced by homologous sequence was strongly suppressed by the immixture infiltration of either the P14 or the S6. In the suppressed plants, the gfp mRNA accumulation was higher than that in the non-suppressed controls and the symptoms caused by PVX infection became more severe, especially the gfp DNA methylation of plant genome was significantly inhabited when co-infiltrated with RBSDV S6 gene. These results suggested that these two virus genes were potentially to encode for proteins as RNA silencing suppressors.

  17. Short communication: Influence of pasteurization on the active compounds in medicinal plants to be used in dairy products

    DEFF Research Database (Denmark)

    Jäger, Anna Katharina; Saaby, Lasse; Kudsk, Dorte Søndergaard

    2010-01-01

    Interest from the dairy industry in adding herbal drugs to milk and yogurt products raises the question of whether these plant materials can be pasteurized. Root material of Rhodiola rosea, Eleutherococcus senticosus, and Panax ginseng, all plants with adaptogenic activities, was pasteurized....... The content of active compounds in the root material before and after pasteurization was quantified by HPLC analysis. The results show that the eleutherosides in E. senticosus, and to an extent the ginsenosides from P. ginseng, could withstand pasteurization, whereas salidroside and rosavin from R. rosea did...

  18. An effective virus-based gene silencing method for functional genomics studies in common bean

    Directory of Open Access Journals (Sweden)

    Kachroo Aardra

    2011-06-01

    Full Text Available Abstract Background Common bean (Phaseolus vulgaris L. is a crop of economic and nutritious importance in many parts of the world. The lack of genomic resources have impeded the advancement of common bean genomics and thereby crop improvement. Although concerted efforts from the "Phaseomics" consortium have resulted in the development of several genomic resources, functional studies have continued to lag due to the recalcitrance of this crop for genetic transformation. Results Here we describe the use of a bean pod mottle virus (BPMV-based vector for silencing of endogenous genes in common bean as well as for protein expression. This BPMV-based vector was originally developed for use in soybean. It has been successfully employed for both protein expression and gene silencing in this species. We tested this vector for applications in common bean by targeting common bean genes encoding nodulin 22 and stearoyl-acyl carrier protein desaturase for silencing. Our results indicate that the BPMV vector can indeed be employed for reverse genetics studies of diverse biological processes in common bean. We also used the BPMV-based vector for expressing the green fluorescent protein (GFP in common bean and demonstrate stable GFP expression in all common bean tissues where BPMV was detected. Conclusions The availability of this vector is an important advance for the common bean research community not only because it provides a rapid means for functional studies in common bean, but also because it does so without generating genetically modified plants. Here we describe the detailed methodology and provide essential guidelines for the use of this vector for both gene silencing and protein expression in common bean. The entire VIGS procedure can be completed in 4-5 weeks.

  19. An efficient virus-induced gene silencing vector for maize functional genomics research.

    Science.gov (United States)

    Wang, Rong; Yang, Xinxin; Wang, Nian; Liu, Xuedong; Nelson, Richard S; Li, Weimin; Fan, Zaifeng; Zhou, Tao

    2016-04-01

    Maize is a major crop whose rich genetic diversity provides an advanced resource for genetic research. However, a tool for rapid transient gene function analysis in maize that may be utilized in most maize cultivars has been lacking, resulting in reliance on time-consuming stable transformation and mutation studies to obtain answers. We developed an efficient virus-induced gene silencing (VIGS) vector for maize based on a naturally maize-infecting cucumber mosaic virus (CMV) strain, ZMBJ-CMV. An infectious clone of ZMBJ-CMV was constructed, and a vascular puncture inoculation method utilizing Agrobacterium was optimized to improve its utility for CMV infection of maize. ZMBJ-CMV was then modified to function as a VIGS vector. The ZMBJ-CMV vector induced mild to moderate symptoms in many maize lines, making it useful for gene function studies in critically important maize cultivars, such as the sequenced reference inbred line B73. Using this CMV VIGS system, expression of two endogenous genes, ZmPDS and ZmIspH, was found to be decreased by 75% and 78%, respectively, compared with non-silenced tissue. Inserts with lengths of 100-300 bp produced the most complete transcriptional and visual silencing phenotypes. Moreover, genes related to autophagy, ZmATG3 and ZmATG8a, were also silenced, and it was found that they function in leaf starch degradation. These results indicate that our ZMBJ-CMV VIGS vector provides a tool for rapid and efficient gene function studies in maize. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

  20. The effect of eccentricity and spatiotemporal energy on motion silencing.

    Science.gov (United States)

    Choi, Lark Kwon; Bovik, Alan C; Cormack, Lawrence K

    2016-01-01

    The now well-known motion-silencing illusion has shown that salient changes among a group of objects' luminances, colors, shapes, or sizes may appear to cease when objects move rapidly (Suchow & Alvarez, 2011). It has been proposed that silencing derives from dot spacing that causes crowding, coherent changes in object color or size, and flicker frequencies combined with dot spacing (Choi, Bovik, & Cormack, 2014; Peirce, 2013; Turi & Burr, 2013). Motion silencing is a peripheral effect that does not occur near the point of fixation. To better understand the effect of eccentricity on motion silencing, we measured the amount of motion silencing as a function of eccentricity in human observers using traditional psychophysics. Fifteen observers reported whether dots in any of four concentric rings changed in luminance over a series of rotational velocities. The results in the human experiments showed that the threshold velocity for motion silencing almost linearly decreases as a function of log eccentricity. Further, we modeled the response of a population of simulated V1 neurons to our stimuli. We found strong matches between the threshold velocities on motion silencing observed in the human experiment and those seen in the energy model of Adelson and Bergen (1985). We suggest the plausible explanation that as eccentricity increases, the combined motion-flicker signal falls outside the narrow spatiotemporal frequency response regions of the modeled receptive fields, thereby reducing flicker visibility.

  1. Meiotic silencing by unpaired DNA: properties, regulation and suppression.

    Science.gov (United States)

    Shiu, Patrick K T; Metzenberg, Robert L

    2002-08-01

    In Neurospora, a gene not paired with a homolog in prophase I of meiosis generates a signal that transiently silences all sequences homologous to it by a process called meiotic silencing by unpaired DNA (MSUD). Thus a deletion mutation in a heterozygous cross is formally "ascus-dominant" because its unpaired wild-type partner silences itself. We describe in detail the isolation of a mutation, Sad-1(UV), that suppresses the dominance of various ascus-dominant mutations. Additional dominant, semidominant, and recessive Sad-1 alleles have been generated by RIP; the DNA of the dominant RIP alleles becomes methylated, but dim-2-dependent methylation is not necessary for silencing. The barrenness of homozygous Sad-1 crosses is not due to the failure to silence unpaired mating-type mat A-2 mat A-3 genes. Transcripts of sad-1(+) can be detected during the sexual phase in a homozygous wild-type cross, indicating that the gene is expressed even if all DNA can pair normally. Meiotic silencing is confined to the ascus in which DNA is unpaired, and silencing does not spread to neighboring asci in a fruiting body of mixed genetic constitution.

  2. Control of thermoacoustic instability with a drum-like silencer

    Science.gov (United States)

    Zhang, Guangyu; Wang, Xiaoyu; Li, Lei; Jing, Xiaodong; Sun, Xiaofeng

    2017-10-01

    Theoretical investigation is carried out by a novel method of controlling thermoacoustic instability with a drum-like silencer. It is shown that by decreasing the frequency of thermoacoustic system, the instability can be suppressed with the help of drum-like silencer. The purely reactive silencer, which is composed of a flexible membrane and a backing cavity, is usually known as a noise control device that works effectively in low frequency bandwidth without any aerodynamic loss. In present research, the silencer is exploited in a Rijke tube, as a means of decreasing the natural frequency of the system, and consequently changing the resonance period of the system. The ;transfer element method; (TEM) is used to consider the interactions between the acoustic waves and the flexible membranes of the silencer. The effects of all possible properties of the silencer on the growth rate and resonance frequency of the thermoacoustic system are explored. According to the calculation results, it is found that for some properties of the silencer, the resonance frequencies are greatly decreased and then the phase difference between the unsteady heat release and the pressure fluctuation is increased. Consequently, the instability is suppressed with some dissipation that can not be able to control its onset in the original system. Therefore, when the damping is low, but not zero, it is effective to control thermoacoustic instability with this technique.

  3. Silence, power and communication in the operating room

    Science.gov (United States)

    Gardezi, Fauzia; Lingard, Lorelei; Espin, Sherry; Whyte, Sarah; Orser, Beverley; Baker, G Ross

    2009-01-01

    Title. Silence, power and communication in the operating room Aim This paper is a report of a study conducted to explore whether a 1- to 3-minute preoperative interprofessional team briefing with a structured checklist was an effective way to support communication in the operating room. Background Previous research suggests that nurses often feel constrained in their ability to communicate with physicians. Previous research on silence and power suggests that silence is not only a reflection of powerlessness or passivity, and that silence and speech are not opposites, but closely interrelated. Methods We conducted a retrospective study of silences observed in communication between nurses and surgeons in a multi-site observational study of interprofessional communication in the operating room. Over 700 surgical procedures were observed from 2005–2007. Instances of communication characterized by unresolved or unarticulated issues were identified in field notes and analysed from a critical ethnography perspective. Findings We identified three forms of recurring ‘silences’: absence of communication; not responding to queries or requests; and speaking quietly. These silences may be defensive or strategic, and they may be influenced by larger institutional and structural power dynamics as well as by the immediate situational context. Conclusions There is no single answer to the question of why ‘nobody said anything’. Exploring silences in relation to power suggests that there are multiple and complex ways that constrained communication is produced in the operating room, which are essential to understand in order to improve interprofessional communication and collaboration.

  4. Multiple Interpretations of EFL Learners’ Silence in the Iranian Context

    Directory of Open Access Journals (Sweden)

    Reza Ghaffar Samar

    2013-11-01

    Full Text Available Attention to silence as part of the communicative discourse was first drawn in Sack’s (1974 paper, in which it was perceived as a linguistic and communicative form, and from the functional point of view as capable of expressing ideational, interpersonal, and textual functions. Awareness of multiple functions of silence including the referential, emotive, conative, phatic, poetic and metalanguage is of greater significance when it comes to language learning settings, where learners from a different cultural background from the target language are present to learn that language.  In such contexts, awareness of various functions of silence and correct interpretation of it is essential in teacher-student rapport. This paper aims to, first, provide an introduction to the multiple functions of silence in general and then to investigate these functions in EFL classes of Iran’s private language institutes. The researchers’ own teaching experience along with class observations and 2 phases of interview with teachers of those classes comprise the research data. Findings were indicative of teachers’ lack of awareness of diverse communicative functions of silence in class and that this awareness could be raised through the informal interview phases. This paper attests to the fact that not all learner’s silence should be interpreted negatively as lack of attention or knowledge. Teachers need to be aware of the salient meanings of silence in their EFL class and take an appropriate reactive step accordingly.

  5. Simultaneous silencing of two arginine decarboxylase genes alters development in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Diana eSánchez-Rangel

    2016-03-01

    Full Text Available Polyamines (PAs are small aliphatic polycations that are found ubiquitously in all organisms. In plants, PAs are involved in diverse biological processes such as growth, development, and stress responses. In Arabidopsis thaliana, the arginine decarboxylase enzymes (ADC1 and 2 catalyze the first step of PA biosynthesis. For a better understanding of PA biological functions, mutants in PA biosynthesis have been generated; however, the double adc1/adc2 mutant is not viable in A. thaliana. In this study, we generated non-lethal A. thaliana lines through an artificial microRNA that simultaneously silenced the two ADC genes (amiR:ADC. The generated transgenic lines (amiR:ADC-L1 and -L2 showed reduced AtADC1 and AtADC2 transcript levels. For further analyses the amiR:ADC-L2 line was selected. We found that the amiR:ADC-L2 line showed a significant decrease of their PA levels. The co-silencing revealed a stunted growth in A. thaliana seedlings, plantlets and delay in its flowering rate; these phenotypes were reverted with PA treatment. In addition, amiR:ADC-L2 plants displayed two seed phenotypes, such as yellow and brownish seeds. The yellow mutant seeds were smaller than adc1, adc2 mutants and wild type seeds; however, the brownish were the smallest seeds with arrested embryos at the torpedo stage. These data reinforce the importance of PA homeostasis in the plant development processes.

  6. Development and use of an efficient DNA-based viral gene silencing vector for soybean.

    Science.gov (United States)

    Zhang, Chunquan; Yang, Chunling; Whitham, Steven A; Hill, John H

    2009-02-01

    Virus-induced gene silencing (VIGS) is increasingly being used as a reverse genetics tool to study functions of specific plant genes. It is especially useful for plants, such as soybean, that are recalcitrant to transformation. Previously, Bean pod mottle virus (BPMV) was shown to be an effective VIGS vector for soybean. However, the reported BPMV vector requires in vitro RNA transcription and inoculation, which is not reliable or amenable to high-throughput applications. To increase the efficiency of the BPMV vector for soybean functional genomics, a DNA-based version was developed. Reported here is the construction of a Cauliflower mosaic virus 35S promoter-driven BPMV vector that is efficient for the study of soybean gene function. The selection of a mild rather than a severe BPMV strain greatly reduced the symptom interference caused by virus infection. The DNA-based BPMV vector was used to silence soybean homologues of genes involved in plant defense, translation, and the cytoskeleton in shoots and in roots. VIGS of the Actin gene resulted in reduced numbers of Soybean mosaic virus infection foci. The results demonstrate the utility of this new vector as an efficient tool for a wide range of applications for soybean functional genomics.

  7. Tobacco calmodulin-like protein provides secondary defense by binding to and directing degradation of virus RNA silencing suppressors.

    Science.gov (United States)

    Nakahara, Kenji S; Masuta, Chikara; Yamada, Syouta; Shimura, Hanako; Kashihara, Yukiko; Wada, Tomoko S; Meguro, Ayano; Goto, Kazunori; Tadamura, Kazuki; Sueda, Kae; Sekiguchi, Toru; Shao, Jun; Itchoda, Noriko; Matsumura, Takeshi; Igarashi, Manabu; Ito, Kimihito; Carthew, Richard W; Uyeda, Ichiro

    2012-06-19

    RNA silencing (RNAi) induced by virus-derived double-stranded RNA (dsRNA), which is in a sense regarded as a pathogen-associated molecular pattern (PAMP) of viruses, is a general plant defense mechanism. To counteract this defense, plant viruses express RNA silencing suppressors (RSSs), many of which bind to dsRNA and attenuate RNAi. We showed that the tobacco calmodulin-like protein, rgs-CaM, counterattacked viral RSSs by binding to their dsRNA-binding domains and sequestering them from inhibiting RNAi. Autophagy-like protein degradation seemed to operate to degrade RSSs with the sacrifice of rgs-CaM. These RSSs could thus be regarded as secondary viral PAMPs. This study uncovered a unique defense system in which an rgs-CaM-mediated countermeasure against viral RSSs enhanced host antiviral RNAi in tobacco.

  8. Rapid screening of RNA silencing suppressors by using a recombinant virus derived from beet necrotic yellow vein virus.

    Science.gov (United States)

    Guilley, H; Bortolamiol, D; Jonard, G; Bouzoubaa, S; Ziegler-Graff, V

    2009-10-01

    To counteract plant defence mechanisms, plant viruses have evolved to encode RNA silencing suppressor (RSS) proteins. These proteins can be identified by a range of silencing suppressor assays. Here, we describe a simple method using beet necrotic yellow vein virus (BNYVV) that allows a rapid screening of RSS activity. The viral inoculum consisted of BNYVV RNA1, which encodes proteins involved in viral replication, and two BNYVV-derived replicons: rep3-P30, which expresses the movement protein P30 of tobacco mosaic virus, and rep5-X, which allows the expression of a putative RSS (X). This approach has been validated through the use of several known RSSs. Two potential candidates have been tested and we show that, in our system, the P13 protein of burdock mottle virus displays RSS activity while the P0 protein of cereal yellow dwarf virus-RPV does not.

  9. Dentin sialophosphoprotein (DSPP gene-silencing inhibits key tumorigenic activities in human oral cancer cell line, OSC2.

    Directory of Open Access Journals (Sweden)

    Rajeshree Joshi

    Full Text Available BACKGROUND: We determined recently that dentin sialophosphoprotein (DSPP, a member of the SIBLING (Small integrin-binding ligand N-linked glycoproteins family of phosphoglycoproteins, is highly upregulated in human oral squamous cell carcinomas (OSCCs where upregulation is associated with tumor aggressiveness. To investigate the effects of DSPP-silencing on the tumorigenic profiles of the oral cancer cell line, OSC2, short-hairpin RNA (shRNA interference was employed to silence DSPP in OSC2 cells. METHODOLOGY/PRINCIPAL FINDINGS: Multiple regions of DSPP transcript were targeted for shRNA interference using hDSP-shRNA lentiviral particles designed to silence DSPP gene expression. Control shRNA plasmid encoding a scrambled sequence incapable of degrading any known cellular mRNA was used for negative control. Following puromycin selection of stable lines of DSSP-silenced OSC2 cells, phenotypic hallmarks of oral carcinogenesis were assayed by western blot and RT-PCR analyses, MTT (cell-viability, colony-formation, modified Boyden-Chamber (migration and invasion, and flow cytometry (cell-cycle and apoptosis analyses. DSPP-silenced OSC2 cells showed altered cell morphology, reduced viability, decreased colony-formation ability, decreased migration and invasion, G0/G1 cell-cycle arrest, and increased tumor cell sensitivity to cisplatin-induced apoptosis. Furthermore, MMP-2, MMP-3, MMP-9, VEGF, Ki-67, p53, and EGFR were down-regulated. There was a direct correlation between the degree of DSPP-silencing and MMP suppression, as indicated by least squares regression: MMP-2 {(y = 0.850x, p<0.001 (y = 1.156x, p<0.001}, MMP-3 {(y = 0.994x, p<0.001 (y = 1.324x, p = 0.004}, and MMP-9 {(y = 1.248x, p = 0.005, y = 0.809, p = 0.013}. CONCLUSIONS/SIGNIFICANCE: DSPP-silencing in OSC2 cell decreased salient hallmarks of oral tumorigenesis and provides the first functional evidence of a potential key role for DSPP in oral cancer

  10. Investigation of transcriptional gene silencing and mechanism induced by shRNAs targeted to RUNX3 in vitro

    Institute of Scientific and Technical Information of China (English)

    Xue-Zhi Feng; Xiu-Sheng He; Ying-Zhi Zhuang; Qiao Luo; Jun-Hao Jiang; Shuai Yang; Xue-Fang Tang; Ju-Lin Liu; Tao Chen

    2008-01-01

    AIM: To investigate transcriptional gene silencing induced by short hairpin RNAs (shRNAs) that target gene prompter regions of RUNX3 gene, and whether shRNAs homologous to DNA sequences may serve as initiators for methylation.METHODS: According to the principle of RNAi design,pSilencer3.1-H1-shRNA/RUNX3 expression vector was constructed, The recombinant plasmid shRNA was transfected into human stomach carcinoma cell line SGC7901 with Lipofectamine 2000. Then, the positive cell clones were screened by G418. The mRNA and protein expression level of RUNX3 in the stable transfected cell line SGC7901 were determined by RT-PCR, Western blotting and immunocytochemistry. Characteristics of the cell lines including SGC7901, pSilencer3.1-H1/SGC7901 and pSilencer3.1-H1-shRNA/RUNX3/SGC7901 were analyzed with growth curves, clone formation rate and cell-cycle distribution. The activated level of RUNX3 was examined after treatment with the different density of 5'-aza-2'-deoxycytidine (5-Aza-CdR) by using semiquantitative RT-PCR and Western blotting.RESULTS: In the cell line SGC7901 transfected with pSilencer3.1-Hl-shRNA/RUNX3, mRNA and protein expression of the RUNX3 gene was lost identified by RTPCR, Western blotting and immunocytochemistry assay.The growth of pSilencer3.1-H1-shRNA/RUNX3/SGC7901cells without expression of RUNX3 was the fastest (P < 0.05), its rate of clone formation was the highest (P <0.01), and the cell distribution in G0/G1 and S/M phases was lowest and highest, respectively (P < 0.05),compared with that of the transfected pSilencer3.1-H1 and non-transfected cells. Through RT-PCR and Western blot assay, inactivated RUNX3 could not be reactivated by 5-Aza-CdR.CONCLUSION: We found that, although shRNAs targeted to gene prompter regions of RUNX3 could effectively induce transcriptional repression with chromatic changes characteristic of inaction promoters, this was independent of DNA methylation, and the presence of RNA-dependent transcriptional silencing

  11. Dynamics of Short-Term Phosphorus Uptake by Intact Mycorrhizal and Non-mycorrhizal Maize Plants Grown in a Circulatory Semi-Hydroponic Cultivation System

    Directory of Open Access Journals (Sweden)

    Mónica Garcés-Ruiz

    2017-08-01

    Full Text Available A non-destructive cultivation system was developed to study the dynamics of phosphorus (Pi uptake by mycorrhizal and non-mycorrhizal maize plantlets. The system consisted of a plant container connected via silicon tubes to a glass bottle containing a nutrient solution supplemented with Pi. The nutrient solution is pumped with a peristaltic pump to the upper part of the container via the silicon tubes and the solution percolate through the plantlet container back into the glass bottle. Pi is sampled from the glass bottle at regular intervals and concentration evaluated. Maize plantlets were colonized by the AMF Rhizophagus irregularis MUCL 41833 and Pi uptake quantified at fixed intervals (9, 21, and 42 h from the depletion of the Pi in the nutrient solution flowing through the plantlets containers. Plants and fungus grew well in the perlite substrate. The concentration of Pi in the bottles followed an almost linear decrease over time, demonstrating a depletion of Pi in the circulating solution and a concomitant uptake/immobilization by the plantlet-AMF associates in the containers. The Pi uptake rate was significantly increased in the AMF-colonized plantlets (at 9 and 21 h as compared to non-colonized plantlets, although no correlation was noticed with plant growth or P accumulation in shoots. The circulatory semi-hydroponic cultivation system developed was adequate for measuring Pi depletion in a nutrient solution and by corollary Pi uptake/immobilization by the plant-AMF associates. The measurements were non-destructive so that the time course of Pi uptake could be monitored without disturbing the growth of the plant and its fungal associate. The system further opens the door to study the dynamics of other micro and macro-nutrients as well as their uptake under stressed growth conditions such as salinity, pollution by hydrocarbon contaminants or potential toxic elements.

  12. Short stature

    Science.gov (United States)

    ... condition. Bone or skeletal disorders, such as: Rickets Achondroplasia Chronic diseases, such as: Asthma Celiac disease Congenital ... growth seems slow or your child seems small. TREATMENT Your child's short stature may affect her self- ...

  13. Short communication

    African Journals Online (AJOL)

    preferred customer

    ABSTRACT: Nutrients, metabolizable energy (ME), anti-nutritional factors, digestible organic ... for animals are in short supply and expensive, ... peels from hotels (Hawassa); sisal waste from ..... chain omega-3 fatty acids in livestock meat and.

  14. silencing COI1 in rice increases susceptibility to chewing insects and impairs inducible defense.

    Directory of Open Access Journals (Sweden)

    Mao Ye

    Full Text Available The jasmonic acid (JA pathway plays a key role in plant defense responses against herbivorous insects. CORONATINE INSENSITIVE1 (COI1 is an F-box protein essential for all jasmonate responses. However, the precise defense function of COI1 in monocotyledonous plants, especially in rice (Oryza sativa L. is largely unknown. We silenced OsCOI1 in rice plants via RNA interference (RNAi to determine the role of OsCOI1 in rice defense against rice leaf folder (LF Cnaphalocrocis medinalis, a chewing insect, and brown planthopper (BPH Nilaparvata lugens, a phloem-feeding insect. In wild-type rice plants (WT, the transcripts of OsCOI1 were strongly and continuously up-regulated by LF infestation and methyl jasmonate (MeJA treatment, but not by BPH infestation. The abundance of trypsin protease inhibitor (TrypPI, and the enzymatic activities of polyphenol oxidase (PPO and peroxidase (POD were enhanced in response to both LF and BPH infestation, but the activity of lipoxygenase (LOX was only induced by LF. The RNAi lines with repressed expression of OsCOI1 showed reduced resistance against LF, but no change against BPH. Silencing OsCOI1 did not alter LF-induced LOX activity and JA content, but it led to a reduction in the TrypPI content, POD and PPO activity by 62.3%, 48.5% and 27.2%, respectively. In addition, MeJA-induced TrypPI and POD activity were reduced by 57.2% and 48.2% in OsCOI1 RNAi plants. These results suggest that OsCOI1 is an indispensable signaling component, controlling JA-regulated defense against chewing insect (LF in rice plants, and COI1 is also required for induction of TrypPI, POD and PPO in rice defense response to LF infestation.

  15. Post-translational regulation of miRNA pathway components, AGO1 and HYL1, in plants

    DEFF Research Database (Denmark)

    Cho, Seok Keun; Ryu, Moon Young; Shah, Pratik

    2016-01-01

    , the complexity of the proteome increases, and this then influences most biological processes. Although small RNAs are crucial regulatory elements for gene expression in most eukaryotes, PTMs of small RNA microprocessor and RNA silencing components have not been extensively investigated in plants. To date...... findings on the PTMs of microprocessor and RNA silencing components in plants....

  16. Characterization of a Brome mosaic virus strain and its use as a vector for gene silencing in monocotyledonous hosts.

    Science.gov (United States)

    Ding, Xin Shun; Schneider, William L; Chaluvadi, Srinivasa Rao; Mian, M A Rouf; Nelson, Richard S

    2006-11-01

    Virus-induced gene silencing (VIGS) is used to analyze gene function in dicotyledonous plants but less so in monocotyledonous plants (particularly rice and corn), partially due to the limited number of virus expression vectors available. Here, we report the cloning and modification for VIGS of a virus from Festuca arundinacea Schreb. (tall fescue) that caused systemic mosaic symptoms on barley, rice, and a specific cultivar of maize (Va35) under greenhouse conditions. Through sequencing, the virus was determined to be a strain of Brome mosaic virus (BMV). The virus was named F-BMV (F for Festuca), and genetic determinants that controlled the systemic infection of rice were mapped to RNAs 1 and 2 of the tripartite genome. cDNA from RNA 3 of the Russian strain of BMV (R-BMV) was modified to accept inserts from foreign genes. Coinoculation of RNAs 1 and 2 from F-BMV and RNA 3 from R-BMV expressing a portion of a plant gene to leaves of barley, rice, and maize plants resulted in visual silencing-like phenotypes. The visual phenotypes were correlated with decreased target host transcript levels in the corresponding leaves. The VIGS visual phenotype varied from maintained during silencing of actin 1 transcript expression to transient with incomplete penetration through affected tissue during silencing of phytoene desaturase expression. F-BMV RNA 3 was modified to allow greater accumulation of virus while minimizing virus pathogenicity. The modified vector C-BMV(A/G) (C for chimeric) was shown to be useful for VIGS. These BMV vectors will be useful for analysis of gene function in rice and maize for which no VIGS system is reported.

  17. Suppression of RNA Silencing by a Geminivirus Nuclear Protein, AC2, Correlates with Transactivation of Host Genes†

    OpenAIRE

    Trinks, Daniela; R Rajeswaran; Shivaprasad, P. V.; Akbergenov, Rashid; Edward J Oakeley; Veluthambi, K; Hohn, Thomas; Pooggin, Mikhail M.

    2005-01-01

    Bipartite geminiviruses encode a small protein, AC2, that functions as a transactivator of viral transcription and a suppressor of RNA silencing. A relationship between these two functions had not been investigated before. We characterized both of these functions for AC2 from Mungbean yellow mosaic virus-Vigna (MYMV). When transiently expressed in plant protoplasts, MYMV AC2 strongly transactivated the viral promoter; AC2 was detected in the nucleus, and a split nuclear localization signal (N...

  18. Increase in flavan-3-ols by silencing flavonol synthase mRNA affects the transcript expression and activity levels of antioxidant enzymes in tobacco.

    Science.gov (United States)

    Mahajan, M; Joshi, R; Gulati, A; Yadav, S K

    2012-09-01

    Flavonoids are plant secondary metabolites widespread throughout the plant kingdom involved in many physiological and biochemical functions. Amongst the flavonoids, flavan-3-ols (catechin and epicatechin) are known for their direct free radical scavenging activity in vitro, but studies on their antioxidant potential and interaction with antioxidant enzymes in vivo are lacking. Here, the flavonoid pathway was engineered by silencing a gene encoding flavonol synthase (FLS) in tobacco to direct the flow of metabolites towards production of flavan-3-ols. FLS silencing reduced flavonol content 17-53%, while it increased catechin and epicatechin content 51-93% and 18-27%, respectively. The silenced lines showed a significant increase in expression of genes for dihydroflavonol reductase and anthocyanidin synthase, a downstream gene towards epicatechin production, with no significant change in expression of other genes of the flavonoid pathway. Effects of accumulation of flavan-3-ols in FLS silenced lines on transcript level and activities of antioxidant enzymes were studied. Transcripts of the antioxidant enzymes glutathione reductase (GR), ascorbate peroxidase (APx), and catalase (CAT) increased, while glutathione-S-transferase (GST), decreased in FLS silenced lines. Enhanced activity of all the antioxidant enzymes was observed in silenced tobacco lines. To validate the affect of flavan-3-ols on the antioxidant system, in vitro experiments were conducted with tobacco seedlings exposed to two concentrations of catechin (10  and 50 μm) for 2 days. In vitro exposed seedlings produced similar levels of transcripts and activity of antioxidant enzymes as FLS silenced seedlings. Results suggest that flavan-3-ols (catechin) might be increasing activity of GR, Apx and CAT by elevating their mRNAs levels. Since these enzymes are involved in scavenging of reactive oxygen species, this strategy would help in tailoring crops for enhanced catechin production as well as making

  19. Virus-induced gene silencing (VIGS) as a reverse genetic tool to study development of symbiotic root nodules

    DEFF Research Database (Denmark)

    Kjær, Gabriela Didina Constantin; Grønlund, Mette; Stougaard, Jens

    2008-01-01

    was mediated by agroinfiltration and, 2 weeks later, a Rhizobium leguminosarum bv. viceae culture was added in order to induce root nodulation. At this time point, it was estimated that systemic silencing was established because leaves of reference plants inoculated with PEBV carrying a fragment of Phytoene...... desaturase displayed photo bleaching. Three weeks after Rhizobium spp. application, plants inoculated with a control vector nodulated normally, whereas nodulation was almost eliminated in plants inoculated with a vector carrying PsNinA and PsNinC. For plants inoculated with a vector carrying Ps......NinB, nodulation was reduced by at least 45%. Down-regulation of PsNin transcripts in plants inoculated with vectors carrying PsNin cDNA fragments was confirmed and these plants displayed a relative increase in the root/shoot ratio, as expected if nitrogen fixation had been impaired....

  20. Expression of RNA-interference/antisense transgenes by the cognate promoters of target genes is a better gene-silencing strategy to study gene functions in rice.

    Directory of Open Access Journals (Sweden)

    Jing Li

    Full Text Available Antisense and RNA interference (RNAi-mediated gene silencing systems are powerful reverse genetic methods for studying gene function. Most RNAi and antisense experiments used constitutive promoters to drive the expression of RNAi/antisense transgenes; however, several reports showed that constitutive promoters were not expressed in all cell types in cereal plants, suggesting that the constitutive promoter systems are not effective for silencing gene expression in certain tissues/organs. To develop an alternative method that complements the constitutive promoter systems, we constructed RNAi and/or antisense transgenes for four rice genes using a constitutive promoter or a cognate promoter of a selected rice target gene and generated many independent transgenic lines. Genetic, molecular, and phenotypic analyses of these RNAi/antisense transgenic rice plants, in comparison to previously-reported transgenic lines that silenced similar genes, revealed that expression of the cognate promoter-driven RNAi/antisense transgenes resulted in novel growth/developmental defects that were not observed in transgenic lines expressing constitutive promoter-driven gene-silencing transgenes of the same target genes. Our results strongly suggested that expression of RNAi/antisense transgenes by cognate promoters of target genes is a better gene-silencing approach to discovery gene function in rice.