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  1. MEF2C and EBF1 Co-regulate B Cell-Specific Transcription.

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    Kong, Nikki R; Davis, Matthew; Chai, Li; Winoto, Astar; Tjian, Robert

    2016-02-01

    Hematopoietic stem cells are capable of self-renewal or differentiation along three main lineages: myeloid, erythroid, and lymphoid. One of the earliest lineage decisions for blood progenitor cells is whether to adopt the lymphoid or myeloid fate. Previous work had shown that myocyte enhancer factor 2C (MEF2C) is indispensable for the lymphoid fate decision, yet the specific mechanism of action remained unclear. Here, we have identified early B cell factor-1 (EBF1) as a co-regulator of gene expression with MEF2C. A genome-wide survey of MEF2C and EBF1 binding sites identified a subset of B cell-specific genes that they target. We also determined that the p38 MAPK pathway activates MEF2C to drive B cell differentiation. Mef2c knockout mice showed reduced B lymphoid-specific gene expression as well as increased myeloid gene expression, consistent with MEF2C's role as a lineage fate regulator. This is further supported by interaction between MEF2C and the histone deacetylase, HDAC7, revealing a likely mechanism to repress the myeloid transcription program. This study thus elucidates both activation and repression mechanisms, identifies regulatory partners, and downstream targets by which MEF2C regulates lymphoid-specific differentiation.

  2. MEF2C and EBF1 Co-regulate B Cell-Specific Transcription.

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    Nikki R Kong

    2016-02-01

    Full Text Available Hematopoietic stem cells are capable of self-renewal or differentiation along three main lineages: myeloid, erythroid, and lymphoid. One of the earliest lineage decisions for blood progenitor cells is whether to adopt the lymphoid or myeloid fate. Previous work had shown that myocyte enhancer factor 2C (MEF2C is indispensable for the lymphoid fate decision, yet the specific mechanism of action remained unclear. Here, we have identified early B cell factor-1 (EBF1 as a co-regulator of gene expression with MEF2C. A genome-wide survey of MEF2C and EBF1 binding sites identified a subset of B cell-specific genes that they target. We also determined that the p38 MAPK pathway activates MEF2C to drive B cell differentiation. Mef2c knockout mice showed reduced B lymphoid-specific gene expression as well as increased myeloid gene expression, consistent with MEF2C's role as a lineage fate regulator. This is further supported by interaction between MEF2C and the histone deacetylase, HDAC7, revealing a likely mechanism to repress the myeloid transcription program. This study thus elucidates both activation and repression mechanisms, identifies regulatory partners, and downstream targets by which MEF2C regulates lymphoid-specific differentiation.

  3. The transcription factor MEF2C mediates cardiomyocyte hypertrophy induced by IGF-1 signaling

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    Munoz, Juan Pablo; Collao, Andres; Chiong, Mario; Maldonado, Carola; Adasme, Tatiana; Carrasco, Loreto; Ocaranza, Paula; Bravo, Roberto; Gonzalez, Leticia; Diaz-Araya, Guillermo [Centro FONDAP Estudios Moleculares de la Celula, Facultad de Medicina, Universidad de Chile, Santiago 8380492 (Chile); Facultad de Ciencias Quimicas y Farmaceuticas, Facultad de Medicina, Universidad de Chile, Santiago 8380492 (Chile); Hidalgo, Cecilia [Centro FONDAP Estudios Moleculares de la Celula, Facultad de Medicina, Universidad de Chile, Santiago 8380492 (Chile); Instituto de Ciencias Biomedicas, Facultad de Medicina, Universidad de Chile, Santiago 8380492 (Chile); Lavandero, Sergio, E-mail: slavander@uchile.cl [Centro FONDAP Estudios Moleculares de la Celula, Facultad de Medicina, Universidad de Chile, Santiago 8380492 (Chile); Facultad de Ciencias Quimicas y Farmaceuticas, Facultad de Medicina, Universidad de Chile, Santiago 8380492 (Chile); Instituto de Ciencias Biomedicas, Facultad de Medicina, Universidad de Chile, Santiago 8380492 (Chile)

    2009-10-09

    Myocyte enhancer factor 2C (MEF2C) plays an important role in cardiovascular development and is a key transcription factor for cardiac hypertrophy. Here, we describe MEF2C regulation by insulin-like growth factor-1 (IGF-1) and its role in IGF-1-induced cardiac hypertrophy. We found that IGF-1 addition to cultured rat cardiomyocytes activated MEF2C, as evidenced by its increased nuclear localization and DNA binding activity. IGF-1 stimulated MEF2 dependent-gene transcription in a time-dependent manner, as indicated by increased MEF2 promoter-driven reporter gene activity; IGF-1 also induced p38-MAPK phosphorylation, while an inhibitor of p38-MAPK decreased both effects. Additionally, inhibitors of phosphatidylinositol 3-kinase and calcineurin prevented IGF-1-induced MEF2 transcriptional activity. Via MEF2C-dependent signaling, IGF-1 also stimulated transcription of atrial natriuretic factor and skeletal {alpha}-actin but not of fos-lux reporter genes. These novel data suggest that MEF2C activation by IGF-1 mediates the pro-hypertrophic effects of IGF-1 on cardiac gene expression.

  4. The transcription factor MEF2C mediates cardiomyocyte hypertrophy induced by IGF-1 signaling

    International Nuclear Information System (INIS)

    Munoz, Juan Pablo; Collao, Andres; Chiong, Mario; Maldonado, Carola; Adasme, Tatiana; Carrasco, Loreto; Ocaranza, Paula; Bravo, Roberto; Gonzalez, Leticia; Diaz-Araya, Guillermo; Hidalgo, Cecilia; Lavandero, Sergio

    2009-01-01

    Myocyte enhancer factor 2C (MEF2C) plays an important role in cardiovascular development and is a key transcription factor for cardiac hypertrophy. Here, we describe MEF2C regulation by insulin-like growth factor-1 (IGF-1) and its role in IGF-1-induced cardiac hypertrophy. We found that IGF-1 addition to cultured rat cardiomyocytes activated MEF2C, as evidenced by its increased nuclear localization and DNA binding activity. IGF-1 stimulated MEF2 dependent-gene transcription in a time-dependent manner, as indicated by increased MEF2 promoter-driven reporter gene activity; IGF-1 also induced p38-MAPK phosphorylation, while an inhibitor of p38-MAPK decreased both effects. Additionally, inhibitors of phosphatidylinositol 3-kinase and calcineurin prevented IGF-1-induced MEF2 transcriptional activity. Via MEF2C-dependent signaling, IGF-1 also stimulated transcription of atrial natriuretic factor and skeletal α-actin but not of fos-lux reporter genes. These novel data suggest that MEF2C activation by IGF-1 mediates the pro-hypertrophic effects of IGF-1 on cardiac gene expression.

  5. MiR-204-5p regulates C2C12 myoblast differentiation by targeting MEF2C and ERRγ.

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    Cheng, Xiao; Du, Jingjing; Shen, Linyuan; Tan, Zhendong; Jiang, Dongmei; Jiang, Anan; Li, Qiang; Tang, Guoqing; Jiang, Yanzhi; Wang, Jinyong; Li, Xuewei; Zhang, Shunhua; Zhu, Li

    2018-03-01

    Myogenic differentiation, which occurs in the process of muscle development, is a highly ordered process. Increasing evidence indicates that microRNAs (miRNAs) are important regulators in myogenic processes. In this study, we found that miR-204-5p expression gradually decreased when myoblasts were induced to differentiate. Our results suggested that miR-204-5p blunted myoblast differentiation, which was accompanied with a decreased proportion of myosin heavy chain (MyHC)-positive cells in myoblasts with augmented expression of miR-204-5p. Furthermore, overexpression of miR-204-5p significantly decreased the MyHC composition of slow-twitch fibers in myoblasts. Luciferase activity assays confirmed that miR-204-5p directly targeted the 3'-untranslated region (3'-UTR) of myocyte enhancer factor 2C (MEF2C) and estrogen-related receptor gamma (ERRγ). Small interfering RNA (siRNA) technology successfully inhibited the expression of MEF2C and ERRγ. Interference with MEF2C or ERRγ inhibited myoblast differentiation and the formation of slow-twitch fibers. Meanwhile, co-transfection of either si-MEF2C or si-ERRγ with miR-204-5p mimics resulted in a more severe attenuation of myogenic differentiation. In summary, this study demonstrates that miR-204-5p inhibits myoblast differentiation by targeting MEF2C and ERRγ. Our findings suggest that miR-204-5p is a potential regulator that could influence myogenesis. Copyright © 2018. Published by Elsevier Masson SAS.

  6. MEF2C Haploinsufficiency features consistent hyperkinesis, variable epilepsy, and has a role in dorsal and ventral neuronal developmental pathways

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    Paciorkowski, Alex R.; Traylor, Ryan N.; Rosenfeld, Jill A.; Hoover, Jacqueline M.; Harris, Catharine J.; Winter, Susan; Lacassie, Yves; Bialer, Martin; Lamb, Allen N.; Schultz, Roger A.; Berry-Kravis, Elizabeth; Porter, Brenda E.; Falk, Marni; Venkat, Anu; Vanzo, Rena J.; Cohen, Julie S.; Fatemi, Ali; Dobyns, William B.; Shaffer, Lisa G.; Ballif, Blake C.; Marsh, Eric D.

    2013-01-01

    MEF2C haploinsufficiency syndrome is an emerging neurodevelopmental disorder associated with intellectual disability, autistic features, epilepsy, and abnormal movements. We report 16 new patients with MEF2C haploinsufficiency, including the oldest reported patient with MEF2C deletion at 5q14.3. We detail the neurobehavioral phenotype, epilepsy, and abnormal movements, and compare our subjects with those previously reported in the literature. We also investigate Mef2c expression in the developing mouse forebrain. A spectrum of neurofunctional deficits emerges, with hyperkinesis a consistent finding. Epilepsy varied from absent to severe, and included intractable myoclonic seizures and infantile spasms. Subjects with partial MEF2C deletion were statistically less likely to have epilepsy. Finally, we confirm that Mef2c is present both in dorsal primary neuroblasts and ventral gamma-aminobutyric acid(GABA)ergic interneurons in the forebrain of the developing mouse. Given interactions with several key neurodevelopmental genes such as ARX, FMR1, MECP2, and TBR1, it appears that MEF2C plays a role in several developmental stages of both dorsal and ventral neuronal cell types. PMID:23389741

  7. MEF2C Interacts With c-FOS in PTH-Stimulated Mmp13 Gene Expression in Osteoblastic Cells.

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    Nakatani, Teruyo; Partridge, Nicola C

    2017-11-01

    Parathyroid hormone (PTH) regulates the transcription of many genes in the osteoblast. One of these genes is Mmp13, which is involved in bone remodeling and early stages of endochondral bone formation. Previously, we reported that PTH induces Mmp13 transcription by regulating the dissociation of histone deacetylase 4 (HDAC4) from runt-related transcription factor 2 (Runx2), and the association of the HATs, p300, and p300/CREB binding protein (CBP)-associated factor. It is known that, in addition to Runx2, HDAC4 binds to the transcription factor, myocyte-specific enhancer factor 2c (MEF2C), and represses its activity. In this work, we investigated whether MEF2C participates in PTH-stimulated Mmp13 gene expression in osteoblastic cells and how it does so. Knockdown of Mef2c in UMR 106-01 cells repressed Mmp13 messenger RNA expression and promoter activity with or without PTH treatment. Chromatin immunoprecipitation (ChIP) assays showed that MEF2C associated with the Mmp13 promoter; this increased after 4 hours of PTH treatment. ChIP-reChIP results indicate that endogenous MEF2C associates with HDAC4 on the Mmp13 promoter; after PTH treatment, this association decreased. From gel shift, ChIP, and promoter-reporter assays, MEF2C was found to associate with the activator protein-1 (AP-1) site without directly binding to DNA and had its stimulatory effect through interaction with c-FOS. In conclusion, MEF2C is necessary for Mmp13 gene expression at the transcriptional level and participates in PTH-stimulated Mmp13 gene expression by increased binding to c-FOS at the AP-1 site in the Mmp13 promoter. The observation of MEF2C interacting with a member of the AP-1 transcription factor family provides knowledge of the functions of HDAC4, c-FOS, and MEF2C. Copyright © 2017 Endocrine Society.

  8. Notch Inhibition Enhances Cardiac Reprogramming by Increasing MEF2C Transcriptional Activity

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    Maria Abad

    2017-03-01

    Full Text Available Conversion of fibroblasts into functional cardiomyocytes represents a potential means of restoring cardiac function after myocardial infarction, but so far this process remains inefficient and little is known about its molecular mechanisms. Here we show that DAPT, a classical Notch inhibitor, enhances the conversion of mouse fibroblasts into induced cardiac-like myocytes by the transcription factors GATA4, HAND2, MEF2C, and TBX5. DAPT cooperates with AKT kinase to further augment this process, resulting in up to 70% conversion efficiency. Moreover, DAPT promotes the acquisition of specific cardiomyocyte features, substantially increasing calcium flux, sarcomere structure, and the number of spontaneously beating cells. Transcriptome analysis shows that DAPT induces genetic programs related to muscle development, differentiation, and excitation-contraction coupling. Mechanistically, DAPT increases binding of the transcription factor MEF2C to the promoter regions of cardiac structural genes. These findings provide mechanistic insights into the reprogramming process and may have important implications for cardiac regeneration therapies.

  9. Nuclear Pores Regulate Muscle Development and Maintenance by Assembling a Localized Mef2C Complex.

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    Raices, Marcela; Bukata, Lucas; Sakuma, Stephen; Borlido, Joana; Hernandez, Leanora S; Hart, Daniel O; D'Angelo, Maximiliano A

    2017-06-05

    Nuclear pore complexes (NPCs) are multiprotein channels connecting the nucleus with the cytoplasm. NPCs have been shown to have tissue-specific composition, suggesting that their function can be specialized. However, the physiological roles of NPC composition changes and their impacts on cellular processes remain unclear. Here we show that the addition of the Nup210 nucleoporin to NPCs during myoblast differentiation results in assembly of an Mef2C transcriptional complex required for efficient expression of muscle structural genes and microRNAs. We show that this NPC-localized complex is essential for muscle growth, myofiber maturation, and muscle cell survival and that alterations in its activity result in muscle degeneration. Our findings suggest that NPCs regulate the activity of functional gene groups by acting as scaffolds that promote the local assembly of tissue-specific transcription complexes and show how nuclear pore composition changes can be exploited to regulate gene expression at the nuclear periphery. Copyright © 2017 Elsevier Inc. All rights reserved.

  10. MEF2C enhances dopaminergic neuron differentiation of human embryonic stem cells in a parkinsonian rat model.

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    Eun-Gyung Cho

    Full Text Available Human embryonic stem cells (hESCs can potentially differentiate into any cell type, including dopaminergic neurons to treat Parkinson's disease (PD, but hyperproliferation and tumor formation must be avoided. Accordingly, we use myocyte enhancer factor 2C (MEF2C as a neurogenic and anti-apoptotic transcription factor to generate neurons from hESC-derived neural stem/progenitor cells (NPCs, thus avoiding hyperproliferation. Here, we report that forced expression of constitutively active MEF2C (MEF2CA generates significantly greater numbers of neurons with dopaminergic properties in vitro. Conversely, RNAi knockdown of MEF2C in NPCs decreases neuronal differentiation and dendritic length. When we inject MEF2CA-programmed NPCs into 6-hydroxydopamine-lesioned parkinsonian rats in vivo, the transplanted cells survive well, differentiate into tyrosine hydroxylase-positive neurons, and improve behavioral deficits to a significantly greater degree than non-programmed cells. The enriched generation of dopaminergic neuronal lineages from hESCs by forced expression of MEF2CA in the proper context may prove valuable in cell-based therapy for CNS disorders such as PD.

  11. MicroRNA profiling during mouse ventricular maturation: a role for miR-27 modulating Mef2c expression.

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    Chinchilla, Ana; Lozano, Estefania; Daimi, Houria; Esteban, Francisco J; Crist, Colin; Aranega, Amelia E; Franco, Diego

    2011-01-01

    non-coding RNA has been recently demonstrated to be a novel mechanism for modulation of gene expression at the post-transcriptional level. The importance of microRNAs in the cardiovascular system is now apparent. Mutations of distinct microRNAs have provided evidence for fundamental roles of microRNAs during cardiovascular development. However, there is limited information about global microRNA profiles during mouse heart development. In this study, we have gained insight from the expression profiles of microRNAs during mouse ventricular development by microarray and qRT-PCR analysis. our microarray analysis reveals that relatively few microRNAs display either increasing or decreasing expression profiles during ventricular chamber formation. Interestingly, most of the differentially expressed microRNAs display a rather discrete peak of expression at particular developmental stages. Furthermore, we demonstrate that microRNA-27b (miR-27b) displays an overt myocardial expression during heart development and that the transcription factor-encoding gene Mef2c is an miR-27b target. our data present a comprehensive profile of microRNA expression during ventricular maturation, providing an entry point for investigation of the functional roles of the most abundantly and differentially expressed microRNAs during cardiogenesis.

  12. Mef2c-F10N enhancer driven β-galactosidase (LacZ) and Cre recombinase mice facilitate analyses of gene function and lineage fate in neural crest cells.

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    Aoto, Kazushi; Sandell, Lisa L; Butler Tjaden, Naomi E; Yuen, Kobe C; Watt, Kristin E Noack; Black, Brian L; Durnin, Michael; Trainor, Paul A

    2015-06-01

    Neural crest cells (NCC) comprise a multipotent, migratory stem cell and progenitor population that gives rise to numerous cell and tissue types within a developing embryo, including craniofacial bone and cartilage, neurons and glia of the peripheral nervous system, and melanocytes within the skin. Here we describe two novel stable transgenic mouse lines suitable for lineage tracing and analysis of gene function in NCC. Firstly, using the F10N enhancer of the Mef2c gene (Mef2c-F10N) linked to LacZ, we generated transgenic mice (Mef2c-F10N-LacZ) that express LacZ in the majority, if not all migrating NCC that delaminate from the neural tube. Mef2c-F10N-LacZ then continues to be expressed primarily in neurogenic, gliogenic and melanocytic NCC and their derivatives, but not in ectomesenchymal derivatives. Secondly, we used the same Mef2c-F10N enhancer together with Cre recombinase to generate transgenic mice (Mef2c-F10N-Cre) that can be used to indelibly label, or alter gene function in, migrating NCC and their derivatives. At early stages of development, Mef2c-F10N-LacZ and Mef2c-F10N-Cre label NCC in a pattern similar to Wnt1-Cre mice, with the exception that Mef2c-F10N-LacZ and Mef2c-F10N-Cre specifically label NCC that have delaminated from the neural plate, while premigratory NCC are not labeled. Thus, our Mef2c-F10N-LacZ and Mef2c-F10N-Cre transgenic mice provide new resources for tracing migratory NCC and analyzing gene function in migrating and differentiating NCC independently of NCC formation. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Low-dose PTH increases osteoblast activity via decreased Mef2c/Sost in senescent osteopenic mice.

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    Saidak, Zuzana; Le Henaff, Carole; Azzi, Sofia; Marty, Caroline; Marie, Pierre J

    2014-10-01

    Intermittent administration of parathyroid hormone (PTH) 1-34 at a standard dose has been shown to induce anabolic effects in bone. However, whether low-dose PTH promotes bone formation during senescence is unknown. To address this issue, we determined the effects of low-dose PTH and analysed the underlying mechanisms in prematurely senescent mice that display osteopenia. Treatment of 9-week-old Samp6 mice for 6 weeks with PTH at a standard dose (100 μg/kg per day) increased vertebral and femoral bone mass and improved bone microarchitecture as a result of increased bone-forming surfaces and mineral apposition rate (MAR). At a tenfold lower dose (10 μg/kg per day), PTH increased axial bone volume and trabecular thickness, as detected by bone histomorphometry but not by micro-computed tomography analysis. This anabolic effect resulted from increased osteoblast activity, as reflected by increased serum N-terminal propeptide of type 1 procollagen (P1NP) levels and MAR, with unchanged bone-forming surface or osteoblast surface. Mechanistically, low-dose PTH increased the expression of osteoblast markers in bone marrow stromal cells and mature osteoblasts, which was associated with increased expression of the Wnt effector Wisp1. Moreover, low-dose PTH decreased the expression of the Mef2c transcription factor, resulting in decreased Sost expression in osteoblasts/osteocytes. These results indicate that PTH at a low dose is effective at promoting bone formation and increased bone volume in senescent osteopenic mice through increased osteoblast activity and modulation of specific Wnt effectors, which raises the potential therapeutic use of intermittent PTH at low dose to increase bone forming activity and bone mass in skeletal senescence. © 2014 Society for Endocrinology.

  14. Analysis of association of MEF2C, SOST and JAG1 genes with bone mineral density in Mexican-Mestizo postmenopausal women

    OpenAIRE

    Velázquez-Cruz, Rafael; Jiménez-Ortega, Rogelio F; Parra-Torres, Alma Y; Castillejos-López, Manuel; Patiño, Nelly; Quiterio, Manuel; Villarreal-Molina, Teresa; Salmerón, Jorge

    2014-01-01

    Background Osteoporosis, a disease characterized by low bone mineral density (BMD), is an important health problem in Mexico. BMD is a highly heritable trait, with heritability estimates of 50-85%. Several candidate genes have been evaluated to identify those involved in BMD variation and the etiology of osteoporosis. This study investigated the possible association of single-nucleotide polymorphisms (SNPs) in the MEF2C, SOST and JAG1 genes with bone mineral density (BMD) variation in postmen...

  15. Analysis of association of MEF2C, SOST and JAG1 genes with bone mineral density in Mexican-Mestizo postmenopausal women.

    Science.gov (United States)

    Velázquez-Cruz, Rafael; Jiménez-Ortega, Rogelio F; Parra-Torres, Alma Y; Castillejos-López, Manuel; Patiño, Nelly; Quiterio, Manuel; Villarreal-Molina, Teresa; Salmerón, Jorge

    2014-11-28

    Osteoporosis, a disease characterized by low bone mineral density (BMD), is an important health problem in Mexico. BMD is a highly heritable trait, with heritability estimates of 50-85%. Several candidate genes have been evaluated to identify those involved in BMD variation and the etiology of osteoporosis. This study investigated the possible association of single-nucleotide polymorphisms (SNPs) in the MEF2C, SOST and JAG1genes with bone mineral density (BMD) variation in postmenopausal Mexican-Mestizo women. Four hundred unrelated postmenopausal women were included in the study. Risk factors were recorded and BMD was measured in total hip, femoral neck and lumbar spine using dual-energy X-ray absorptiometry. In an initial stage, a total of twenty-five SNPs within or near SOST gene and seven SNPs in the JAG1 gene were genotyped using a GoldenGate assay. In a second stage, three MEF2C gene SNPs were also genotyped and SOST and JAG1 gene variants were validated. Real time PCR and TaqMan probes were used for genotyping. Linear regression analyses adjusted by age, body mass index and ancestry estimates, showed that five SNPs in the SOST gene were significantly associated with BMD in total hip and femoral neck but not lumbar spine. The lowest p value was 0.0012, well below the multiple-test significance threshold (p=0.009), with mean effect size of -0.027 SD per risk allele. We did not find significant associations between BMD and MEF2C/JAG1 gene variants [rs1366594 "A" allele: β=0.001 (95% CI -0.016; 0.017), P=0.938; rs2273061 "G" allele: β=0.007 (95% CI -0.007; 0.023), p=0.409]. SOST polymorphisms may contribute to total hip and femoral neck BMD variation in Mexican postmenopausal women. Together, these and prior findings suggest that this gene may contribute to BMD variation across populations of diverse ancestry.

  16. Involment of RAS/ERK1/2 signaling and MEF2C in miR-155-3p inhibition-triggered cardiomyocyte differentiation of embryonic stem cell.

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    Ling, Xiang; Yao, Dongbo; Kang, Lumei; Zhou, Jing; Zhou, Ying; Dong, Hui; Zhang, Keping; Zhang, Lei; Chen, Hongping

    2017-10-13

    MicroRNAs (miRNAs) are short, noncoding RNAs that regulate post-transcriptional gene expression by targeting messenger RNAs (mRNAs) for cleavage or translational repression. Growing evidence indicates that miR-155 expression changes with the development of heart and plays an important role in heart physiopathology. However, the role of miR-155 in cardiac cells differentiation is unclear. Using the well-established embryonic stem cell (ESC), we demonstrated that miR-155-3p expression was down-regulated during cardiogenesis from mouse ESC. By contrast, the myogenic enhance factor 2C (MEF2C), a predicted target gene of miR-155-3p, was up-regulated. We further demonstrated that miR-155-3p inhibition increased the percentage of embryoid bodies (EB) beating and up-regulated the expression of cardiac specific markers, GATA4, Nkx2.5, and cTnT mRNA and protein. Notably, miR-155-3p inhibition caused upregulation of MEF2C, KRAS and ERK1/2. ERK1/2 inhibitor, PD98059 significantly decreased the expression of MEF2C protein. These findings indicate that miR-155-3p inhibition promotes cardiogenesis, and its mechanisms are involved in the RAS-ERK1/2 signaling and MEF2C.

  17. MEF2C haploinsufficiency caused by either microdeletion of the 5q14.3 region or mutation is responsible for severe mental retardation with stereotypic movements, epilepsy and/or cerebral malformations.

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    Le Meur, N; Holder-Espinasse, M; Jaillard, S; Goldenberg, A; Joriot, S; Amati-Bonneau, P; Guichet, A; Barth, M; Charollais, A; Journel, H; Auvin, S; Boucher, C; Kerckaert, J-P; David, V; Manouvrier-Hanu, S; Saugier-Veber, P; Frébourg, T; Dubourg, C; Andrieux, J; Bonneau, D

    2010-01-01

    Over the last few years, array-comparative genomic hybridisation (CGH) has considerably improved our ability to detect cryptic unbalanced rearrangements in patients with syndromic mental retardation. Molecular karyotyping of six patients with syndromic mental retardation was carried out using whole-genome oligonucleotide array-CGH. 5q14.3 microdeletions ranging from 216 kb to 8.8 Mb were detected in five unrelated patients with the following phenotypic similarities: severe mental retardation with absent speech, hypotonia and stereotypic movements. Facial dysmorphic features, epilepsy and/or cerebral malformations were also present in most of these patients. The minimal common deleted region of these 5q14 microdeletions encompassed only MEF2C, the gene for a protein known to act in brain as a neurogenesis effector, which regulates excitatory synapse number. In a patient with a similar phenotype, an MEF2C nonsense mutation was subsequently identified. Taken together, these results strongly suggest that haploinsufficiency of MEF2C is responsible for severe mental retardation with stereotypic movements, seizures and/or cerebral malformations.

  18. Myocyte-specific enhancer binding factor 2C (MEF2C expression in the dentate gyrus during development and after pilocarpine-induced status epilepticus: a preliminary report Realce miócito específico ligado a expressão do fator 2C (MEF2C no giro denteado durante o desenvolvimento e após uso de pilocarpina induzindo status epilepticus: estudo preliminar

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    Carla Alessandra Scorza

    2008-01-01

    Full Text Available OBJECTIVE: As axon outgrowth and dentate granule cell neurogenesis are hallmarks of hippocampal development and are also the two morphologic changes in the structure of the dentate gyrus after status epilepticus (SE, we hypothesized that molecules involved in normal development may also play a role during epileptogenesis. METHOD: Using in situ hybridization, we have characterized mRNA expression of myocyte-specific enhancer binding factor 2C (MEF2C in the dentate gyrus during development (P0, P3, P7, P14 and P28 and at multiple time points following pilocarpine-induced SE (3, 7, 14, 28 days after SE. RESULTS: It was demonstrated that MEF2C is up-regulated during development (P0, P3, P7, P14 and P28 and in the adult rat dentate gyrus following SE (3, 7, 14, 28 days after SE. CONCLUSIONS: The molecules controlling cell-fate decisions in the developing dentate gyrus are also operative during epileptogenesis.OBJETIVO: Como o crescimento axonal e a neurogênese do giro denteado são características intrínsecas do hipocampo durante o processo de desenvolvimento, e também são duas alterações morfológicas na estrutura do giro denteado após o status epilepticus (SE, nós hipotetizamos que as moléculas envolvidas no processo normal do desenvolvimento hipocampal também podem participar do processo de epileptogênese. MÉTODO: Utilizando hibridização in situ, caracterizamos a expressão do RNAm do fator de transcrição myocyte-specific enhancer binding factor 2C (MEF2C no giro denteado durante o desenvolvimento (P0, P3, P7, P14 e P28 e em diferentes períodos após o SE (3, 7, 14, 28 dias após SE. RESULTADOS: Foi demonstrado um aumento da expressão de MEF2C no giro denteado durante o desenvolvimento e no giro denteado de animais adultos após o SE. CONCLUSÃO: As moléculas que controlam o destino celular durante o processo de desenvolvimento também estão operativas durante o processo de epileptogênese.

  19. SOCS3 Silencing Attenuates Eosinophil Functions in Asthma Patients

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    Zafra, Mª Paz; Cañas, Jose A.; Mazzeo, Carla; Gámez, Cristina; Sanz, Veronica; Fernández-Nieto, Mar; Quirce, Santiago; Barranco, Pilar; Ruiz-Hornillos, Javier; Sastre, Joaquín; del Pozo, Victoria

    2015-01-01

    Eosinophils are one of the key inflammatory cells in asthma. Eosinophils can exert a wide variety of actions through expression and secretion of multiple molecules. Previously, we have demonstrated that eosinophils purified from peripheral blood from asthma patients express high levels of suppressor of cytokine signaling 3 (SOCS3). In this article, SOCS3 gene silencing in eosinophils from asthmatics has been carried out to achieve a better understanding of the suppressor function in eosinophils. SOCS3 siRNA treatment drastically reduced SOCS3 expression in eosinophils, leading to an inhibition of the regulatory transcription factors GATA-3 and FoxP3, also interleukin (IL)-10; in turn, an increased STAT3 phosphorilation was observed. Moreover, SOCS3 abrogation in eosinophils produced impaired migration, adhesion and degranulation. Therefore, SOCS3 might be regarded as an important regulator implicated in eosinophil mobilization from the bone marrow to the lungs during the asthmatic process. PMID:25764157

  20. Silencing of TGIF attenuates the tumorigenicity of A549 cells in vitro and in vivo.

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    Wang, Yadong; Pan, Teng; Wang, Haiyu; Li, Li; Li, Jiangmin; Zhang, Congke; Yang, Haiyan

    2016-09-01

    The aim of this study was to investigate the effects of the silencing of the TG-interacting factor (TGIF) on the tumorigenicity of A549 cells in vitro and in vivo. Stable TGIF-silenced A549 cells were established by infecting shRNA lentiviral particles. Western blotting analysis was used to detect the expression of proteins. Cell cycle was detected by flow cytometry. Soft agar assay and tumor formation assay in nude mice were applied. The silencing of TGIF inhibited A549 cell proliferation, colony formation in vitro, growth of tumor xenograft in vivo, and arrested the cell cycle in the G1 phase. The expression of CDK4, cyclin D1, and phospho-Rb was markedly decreased in the A549-shTGIF cells compared with the A549-shcon cells, and p21 was markedly increased in the A549-shTGIF cells compared with the A549-shcon cells. A lower level of β-Catenin protein expression was observed in the A549-shTGIF cells than that in the A549-shcon cells. The silencing of TGIF attenuates the tumorigenicity of A549 cells in vitro and in vivo.

  1. MicroRNA-208a Silencing Attenuates Doxorubicin Induced Myocyte Apoptosis and Cardiac Dysfunction

    Directory of Open Access Journals (Sweden)

    Hasahya Tony

    2015-01-01

    Full Text Available Aims. GATA4 depletion is a distinct mechanism by which doxorubicin leads to cardiomyocyte apoptosis, and preservation of GATA4 mitigates doxorubicin induced myocyte apoptosis and cardiac dysfunction. We investigated a novel approach of attenuating doxorubicin induced cardiac toxicity by silencing miR-208a, a heart specific microRNA known to target GATA4. Methods and Results. Eight-week-old female Balb/C mice were randomly assigned to sham, antagomir, and control groups. Antagomir group were pretreated with miR-208a antagomir 4 days before doxorubicin administration. At day 0, control and antagomir groups received 20 mg/kg of doxorubicin, while sham mice received phosphate buffered solution. Echocardiography was done at day 7, after which animals were sacrificed and hearts harvested and assessed for apoptosis and expression of miR-208a, GATA4, and BCL-2. Doxorubicin significantly upregulated miR-208a, downregulated GATA4, and increased myocyte apoptosis, with resulting decrease in cardiac function. In contrast, therapeutic silencing of miR-208a salvaged GATA4 and BCL-2 and decreased apoptosis, with improvement in cardiac function. Conclusion. Doxorubicin upregulates miR-208a and promotes cardiomyocyte apoptosis, while therapeutic silencing of miR-208a attenuates doxorubicin induced myocyte apoptosis with subsequent improvement in cardiac function. These novel results highlight the therapeutic potential of targeting miR-208a to prevent doxorubicin cardiotoxicity.

  2. An Investigation of Acoustic Attenuation Performance of Silencers with Mean Flow Based on Three-Dimensional Numerical Simulation

    Directory of Open Access Journals (Sweden)

    Wei Fan

    2016-01-01

    Full Text Available Transmission loss (TL is often used to evaluate the acoustic attenuation performance of a silencer. In this work, a three-dimensional (3D finite element method (FEM is employed to calculate the TL of some representative silencers, namely, circular expansion chamber silencer and straight-through perforated pipe silencer. In order to account for the effect of mean flow that exists inside the silencer, the 3D FEM is used in conjunction with the Computational Fluid Dynamics (CFD simulation of the flow field. More concretely, the 3D mean flow field is computed by firstly using CFD, and then the obtained mean flow data are imported to an acoustic solution undertaken using FEM. The data transfer between the two steps is accomplished by mesh mapping. The results presented demonstrate good agreement between present TL predictions and previously published experimental and numerical works. Also, the details of the flow inside the silencers may be studied. Furthermore, the effect of mean flow velocity on acoustic attenuation performance of the silencers is investigated. It is concluded that for the studied silencers, in general, increasing flow velocity increases the TL and decreases the resonance peaks.

  3. Trophozoites of Entamoeba histolytica epigenetically silenced in several genes are virulence-attenuated

    Directory of Open Access Journals (Sweden)

    Mirelman D.

    2008-09-01

    Full Text Available The human intestinal parasite Entamoeba histolytica causes amoebic colitis and amoebic liver abscesses. Three classes of amoebic molecules have been identified as the major virulence factors, the Gal/GalNAc inhibitable lectin that mediates adherence to mammalian cells, the amoebapores which cause the formation of membrane ion channels in the target cells and the cysteine proteinases which degrade the matrix proteins, the intestinal mucus and secretory IgA. Transcriptional silencing of the amoebapore (Ehap-a gene occurred after transfection of trophozoites with a plasmid containing a segment of the 5’ upstream region of the gene. Transcriptional silencing of the Ehap-a gene continued even after the removal of the plasmid and the cloned amoebae were termed G3. Transfection of G3 trophozoites with a plasmid construct containing the cysteine proteinase (EhCP-5 gene and the light subunit of the Gal- lectin (Ehlgl1 gene, each under the 5’ upstream sequences of the amoebapore gene, caused the simultaneous epigenetic silencing of expression of these two genes. The resulting trophozoites, termed RB-9, were cured from the plasmid and they do not express the three types of virulent genes. The RB-9 amoeba are virulence attenuated and are incapable of killing mammalian cells, they can not induce the formation of liver abscesses and they do not cause ulcerations in the cecum of experimental animals. The gene-silenced amoebae express the same surface antigens which are present in virulent strains and following intra peritoneal inoculation of live trophozoites into hamsters they evoked a protective immune response. Further studies are needed to find out if RB-9 trophozoites could be used for vaccination against amoebaisis.

  4. JAZF1 promotes proliferation of C2C12 cells, but retards their myogenic differentiation through transcriptional repression of MEF2C and MRF4—Implications for the role of Jazf1 variants in oncogenesis and type 2 diabetes

    Energy Technology Data Exchange (ETDEWEB)

    Yuasa, Katsutoshi; Aoki, Natsumi; Hijikata, Takao, E-mail: hijikata@musashino-u.ac.jp

    2015-08-15

    Single-nucleotide polymorphisms associated with type 2 diabetes (T2D) have been identified in Jazf1, which is also involved in the oncogenesis of endometrial stromal tumors. To understand how Jazf1 variants confer a risk of tumorigenesis and T2D, we explored the functional roles of JAZF1 and searched for JAZF1 target genes in myogenic C2C12 cells. Consistent with an increase of Jazf1 transcripts during myoblast proliferation and their decrease during myogenic differentiation in regenerating skeletal muscle, JAZF1 overexpression promoted cell proliferation, whereas it retarded myogenic differentiation. Examination of myogenic genes revealed that JAZF1 overexpression transcriptionally repressed MEF2C and MRF4 and their downstream genes. AMP deaminase1 (AMPD1) was identified as a candidate for JAZF1 target by gene array analysis. However, promoter assays of Ampd1 demonstrated that mutation of the putative binding site for the TR4/JAZF1 complex did not alleviate the repressive effects of JAZF1 on promoter activity. Instead, JAZF1-mediated repression of Ampd1 occurred through the MEF2-binding site and E-box within the Ampd1 proximal regulatory elements. Consistently, MEF2C and MRF4 expression enhanced Ampd1 promoter activity. AMPD1 overexpression and JAZF1 downregulation impaired AMPK phosphorylation, while JAZF1 overexpression also reduced it. Collectively, these results suggest that aberrant JAZF1 expression contributes to the oncogenesis and T2D pathogenesis. - Highlights: • JAZF1 promotes cell cycle progression and proliferation of myoblasts. • JAZF1 retards myogenic differentiation and hypertrophy of myotubes. • JAZF1 transcriptionally represses Mef2C and Mrf4 expression. • JAZF1 has an impact on the phosphorylation of AMPK.

  5. Bcl-2 silencing attenuates hypoxia-induced apoptosis resistance in pulmonary microvascular endothelial cells.

    Science.gov (United States)

    Cao, Yongmei; Jiang, Zhen; Zeng, Zhen; Liu, Yujing; Gu, Yuchun; Ji, Yingying; Zhao, Yupeng; Li, Yingchuan

    2016-01-01

    Pulmonary arterial hypertension (PAH) is a life-threatening disorder that ultimately causes heart failure. While the underlying causes of this condition are not well understood, previous studies suggest that the anti-apoptotic nature of pulmonary microvascular endothelial cells (PMVECs) in hypoxic environments contributes to PAH pathogenesis. In this study, we focus on the contribution of Bcl-2 and hypoxia response element (HRE) to apoptosis-resistant endothelial cells and investigate the mechanism. PMVECs obtained from either normal rats or apoptosis-resistant PMVECs obtained from PAH rats were transduced with recombinant lentiviral vectors carrying either Bcl-2-shRNA or HRE combined Bcl-2-shRNA, and then cultured these cells for 24 h under hypoxic (5% O2) or normoxic (21% O2) conditions. In normal PMVECs, Bcl-2-shRNA or HRE combined with Bcl-2-shRNA transduction successfully decreased Bcl-2 expression, while increasing apoptosis as well as caspase-3 and P53 expression in a normoxic environment. In a hypoxic environment, the effects of Bcl-2-shRNA treatment on cell apoptosis, and on Bcl-2, caspase-3, P53 expression were significantly suppressed. Conversely, HRE activation combined with Bcl-2-shRNA transduction markedly enhanced cell apoptosis and upregulated caspase-3 and P53 expression, while decreasing Bcl-2 expression. Furthermore, in apoptosis-resistant PMVECs, HRE-mediated Bcl-2 silencing effectively enhanced cell apoptosis and caspase-3 activity. The apoptosis rate was significantly depressed when Lv-HRE-Bcl-2-shRNA was combined with Lv-P53-shRNA or Lv-caspase3-shRNA transduction in a hypoxic environment. These results suggest that HRE-mediated Bcl-2 inhibition can effectively attenuate hypoxia-induced apoptosis resistance in PMVECs by downregulating Bcl-2 expression and upregulating caspase-3 and P53 expression. This study therefore reveals critical insight into potential therapeutic targets for treating PAH.

  6. Attenuation of low frequency duct noise by a flute-like silencer

    Science.gov (United States)

    Huang, Lixi

    2009-09-01

    A broadband, duct noise reflection mechanism is introduced in this theoretical study. It consists of side-branch cavities filled with a light gas, e.g. helium, and covered by impervious, tensioned membranes as two apertures, one at the inlet and another at the exit. Incident waves are scattered by the membranes into two passages, one through the central duct and another through the cavity bypass. Due to the faster speed of sound in the bypass, a Herschel-Quincke tube resonance appears and gives a peak in the transmission loss spectrum. Another resonance occurs when the frequency of the incident sound coincides with the vibroacoustic frequency determined by the membrane tension and inertia contributions from the membrane and the fluid media. With appropriate tensile stress, the trough between the two spectral peaks can be elevated to a desirable high level, e.g. 10 dB, and the crucial factor is identified as the low density of the cavity gas filling. The broadband sound reflection performance is comparable with and even exceeds that of the drum-like silencer [L. Huang, Parametric study of a drum-like silencer, Journal of Sound and Vibration 269 (2004) 467-488] with the same cavity geometry, but the current mechanism requires a low tensile stress which is much easier to implement in practice.

  7. 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...

  8. The Silencing of Pokemon Attenuates the Proliferation of Hepatocellular Carcinoma Cells In Vitro and In Vivo by Inhibiting the PI3K/Akt Pathway

    OpenAIRE

    Lin, Chan-Chan; Zhou, Jing-Ping; Liu, Yun-Peng; Liu, Jing-Jing; Yang, Xiao-Ning; Jazag, Amarsanaa; Zhang, Zhi-Ping; Guleng, Bayasi; Ren, Jian-Lin

    2012-01-01

    Pokemon (POK erythroid myeloid ontogenic factor), which belongs to the POK protein family, is also called LRF, OCZF and FBI-1. As a transcriptional repressor, Pokemon assumes a critical function in cellular differentiation and oncogenesis. Our study identified an oncogenic role for Pokemon in human hepatocellular carcinoma (HCC). We successfully established human HepG2 and Huh-7 cell lines in which Pokemon was stably knocked down. We demonstrated that Pokemon silencing inhibited cell prolifer...

  9. The silencing of Pokemon attenuates the proliferation of hepatocellular carcinoma cells in vitro and in vivo by inhibiting the PI3K/Akt pathway.

    Directory of Open Access Journals (Sweden)

    Chan-Chan Lin

    Full Text Available Pokemon (POK erythroid myeloid ontogenic factor, which belongs to the POK protein family, is also called LRF, OCZF and FBI-1. As a transcriptional repressor, Pokemon assumes a critical function in cellular differentiation and oncogenesis. Our study identified an oncogenic role for Pokemon in human hepatocellular carcinoma (HCC. We successfully established human HepG2 and Huh-7 cell lines in which Pokemon was stably knocked down. We demonstrated that Pokemon silencing inhibited cell proliferation and migration. Pokemon knockdown inhibited the PI3K/Akt and c-Raf/MEK/ERK pathways and modulated the expression of various cell cycle regulators in HepG2 and Huh-7 cells. Therefore, Pokemon may also be involved in cell cycle progression in these cells. We confirmed that Pokemon silencing suppresses hepatocellular carcinoma growth in tumor xenograft mice. These results suggest that Pokemon promotes cell proliferation and migration in hepatocellular carcinoma and accelerates tumor development in an Akt- and ERK-signaling-dependent manner.

  10. The silencing of Pokemon attenuates the proliferation of hepatocellular carcinoma cells in vitro and in vivo by inhibiting the PI3K/Akt pathway.

    Science.gov (United States)

    Lin, Chan-Chan; Zhou, Jing-Ping; Liu, Yun-Peng; Liu, Jing-Jing; Yang, Xiao-Ning; Jazag, Amarsanaa; Zhang, Zhi-Ping; Guleng, Bayasi; Ren, Jian-Lin

    2012-01-01

    Pokemon (POK erythroid myeloid ontogenic factor), which belongs to the POK protein family, is also called LRF, OCZF and FBI-1. As a transcriptional repressor, Pokemon assumes a critical function in cellular differentiation and oncogenesis. Our study identified an oncogenic role for Pokemon in human hepatocellular carcinoma (HCC). We successfully established human HepG2 and Huh-7 cell lines in which Pokemon was stably knocked down. We demonstrated that Pokemon silencing inhibited cell proliferation and migration. Pokemon knockdown inhibited the PI3K/Akt and c-Raf/MEK/ERK pathways and modulated the expression of various cell cycle regulators in HepG2 and Huh-7 cells. Therefore, Pokemon may also be involved in cell cycle progression in these cells. We confirmed that Pokemon silencing suppresses hepatocellular carcinoma growth in tumor xenograft mice. These results suggest that Pokemon promotes cell proliferation and migration in hepatocellular carcinoma and accelerates tumor development in an Akt- and ERK-signaling-dependent manner.

  11. Silencing of P2X7R by RNA interference in the hippocampus can attenuate morphological and behavioral impact of pilocarpine-induced epilepsy.

    Science.gov (United States)

    Amorim, Rebeca Padrão; Araújo, Michelle Gasparetti Leão; Valero, Jorge; Lopes-Cendes, Iscia; Pascoal, Vinicius Davila Bitencourt; Malva, João Oliveira; da Silva Fernandes, Maria José

    2017-12-01

    Cell signaling mediated by P2X7 receptors (P2X7R) has been suggested to be involved in epileptogenesis, via modulation of intracellular calcium levels, excitotoxicity, activation of inflammatory cascades, and cell death, among other mechanisms. These processes have been described to be involved in pilocarpine-induced status epilepticus (SE) and contribute to hyperexcitability, resulting in spontaneous and recurrent seizures. Here, we aimed to investigate the role of P2X7R in epileptogenesis in vivo using RNA interference (RNAi) to inhibit the expression of this receptor. Small interfering RNA (siRNA) targeting P2X7R mRNA was injected into the lateral ventricles (icv) 6 h after SE. Four groups were studied: Saline-Vehicle, Saline-siRNA, Pilo-Vehicle, and Pilo-siRNA. P2X7R was quantified by western blotting and neuronal death assessed by Fluoro-Jade B histochemistry. The hippocampal volume (edema) was determined 48 h following RNAi. Behavioral parameters as latency to the appearance of spontaneous seizures and the number of seizures were determined until 60 days after the SE onset. The Saline-siRNA and Pilo-siRNA groups showed a 43 and 37% reduction, respectively, in P2X7R protein levels compared to respective vehicle groups. Neuroprotection was observed in CA1 and CA3 of the Pilo-siRNA group compared to Pilo-Vehicle. P2X7R silencing in pilocarpine group reversed the increase in the edema detected in the hilus, suprapyramidal dentate gyrus, CA1, and CA3; reduced mortality rate following SE; increased the time to onset of spontaneous seizure; and reduced the number of seizures, when compared to the Pilo-Vehicle group. Therefore, our data highlights the potential of P2X7R as a therapeutic target for the adjunct treatment of epilepsy.

  12. My Day of Silence.

    Science.gov (United States)

    Brown, Scott C.

    1999-01-01

    A heterosexual doctoral student discusses his experiences when he tries to take part in a day of silence to help combat homophobia and heterosexism. His vow of silence teaches him that he will never fully understand the experience of a person who has been historically, socially, and legally silent. (Author/MKA)

  13. Silencing criticism in Mexico

    Directory of Open Access Journals (Sweden)

    Ximena Suárez

    2017-10-01

    Full Text Available Journalists and human rights defenders in Mexico are being attacked in an attempt to silence their criticism. Many are forced to flee or risk being assassinated. The consequences are both personal and of wider social significance.

  14. 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...

  15. 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.

  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. The Fruit of Silence

    Science.gov (United States)

    Nelson, Marilyn

    2006-01-01

    This presentation explores how contemplative practices, especially those anchored in an active listening to silence, are integrated into creative writing courses. It pays particular attention to a course taught at the United States Military Academy at West Point and to a course on the poetry of war and peace taught at the University of…

  18. Silence of the Genes

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 4. Silence of the Genes - 2006 Nobel Prize in Physiology or Medicine. Utpal Nath Saumitra Das. General Article Volume 12 Issue 4 April 2007 pp 6-18. Fulltext. Click here to view fulltext PDF. Permanent link:

  19. Silence of the Genes

    Indian Academy of Sciences (India)

    Srimath

    The human genome codes for ~35,000 genes and all these genes are not expressed in every cell. The time and site of gene expression is very precisely regulated. In any cell, only. Silence of the Genes. 2006 Nobel Prize in Physiology or Medicine. Utpal Nath and Saumitra Das. Keywords. RNA interference, siRNA,.

  20. Gas turbine exhaust system silencing design

    International Nuclear Information System (INIS)

    Ozgur, D.

    1991-01-01

    Gas turbines are the preferred prime mover in many applications because of their high efficiency, fuel flexibility, and low environmental impact. A typical mid-size machine might have a power rating of 80 MW, a flow of about 1000 kg/hr, and an exhaust temperature of over 500C. The most powerful single source of noise is generally the exhaust, which may generate over a kilowatt of acoustic energy. This paper reports that there are two important ways in which exhaust systems can radiate noise. The first is through the discharge of the exhaust duct, with the exhaust gas. Because of the large quantity of hot gas, the duct exit is always oriented vertically; it may be fairly high in the air in order to promote dispersion of the exhaust plume. This source is almost always attenuated by means of a silencer located somewhere in the ductwork. The second source of noise is often called breakout; it is the radiation of exhaust noise through the walls of the ducting. Breakout is most important for those sections of the exhaust duct which lie upstream of the silencer, where sound levels inside the ducting are highest. Both exhaust duct exit noise and breakout noise can be calculated from the sound power level of the gas turbine exhaust and the sound transmission loss (TL) of the silencer and ducting

  1. Histone Demethylase JMJD2A Inhibition Attenuates Neointimal Hyperplasia in the Carotid Arteries of Balloon-Injured Diabetic Rats via Transcriptional Silencing: Inflammatory Gene Expression in Vascular Smooth Muscle Cells

    Directory of Open Access Journals (Sweden)

    Hu Qi

    2015-09-01

    Full Text Available Background/Aims: Diabetic patients suffer from severe neointimal hyperplasia following angioplasty. The epigenetic abnormalities are increasingly considered to be relevant to the pathogenesis of diabetic cardiovascular complications. But the epigenetic mechanisms linking diabetes and coronary restenosis have not been fully elucidated. In this study, we explored the protective effect and underlying mechanisms of demethylases JMJD2A inhibition in balloon-injury induced neointimal formation in diabetic rats. Methods: JMJD2A inhibition was achieved by the chemical inhibitor 2,4-pyridinedicarboxylic acid (2,4-PDCA and small interfering RNA (siRNA. In vitro, we investigated the proliferation, migration and inflammation of rat vascular smooth muscle cells (VSMCs in response to high glucose (HG. In vivo, diabetic rats induced using high-fat diet and low-dose streptozotocin (35mg/kg underwent carotid artery balloon injury. Morphometric analysis was performed using hematein eosin and immumohistochemical staining. Chromatin Immunoprecipitation (ChIP was conducted to detect modification of H3K9me3 at inflammatory genes promoters. Results: The global JMJD2A was increased in HG-stimulated VSMCs and balloon-injured arteries of diabetic rats, accompanied by decreased H3K9me3. The inhibition of JMJD2A suppressed VSMCs proliferation, migration and inflammation induced by high glucose (HG in vitro. And JMJDA2A inhibition attenuated neointimal formation in balloon-injured diabetic rats. The underlying mechanisms were relevant to the restoration of H3K9me3 levels at the promoters of MCP-1 and IL-6, and then the suppressed expression of MCP-1 and IL-6. Conclusion: The JMJD2A inhibition significantly attenuated neointimal formation in balloon injured diabetic rats via the suppression of VSMCs proliferation, migration, and inflammation by restoring H3K9me3.

  2. 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...

  3. Memories Persist in Silence

    OpenAIRE

    Sandra Patricia Arenas Grisales

    2012-01-01

    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 ...

  4. 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.

  5. "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…

  6. 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.

  7. 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,…

  8. 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…

  9. 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.

  10. Zingerone silences quorum sensing and attenuates virulence of Pseudomonas aeruginosa.

    Science.gov (United States)

    Kumar, Lokender; Chhibber, Sanjay; Kumar, Rajnish; Kumar, Manoj; Harjai, Kusum

    2015-04-01

    Quorum sensing in Pseudomonas aeruginosa plays an imperative role in virulence factor, biofilm formation and antimicrobial resistance. Blocking quorum sensing pathways are viewed as viable anti-virulent therapy in association with traditional antimicrobial therapy. Anti-quorum sensing dietary phytochemicals with may prove to be a safe and viable choice as anti-virulent drug candidates. Previously, our lab proved zingerone as potent anti-biofilm agent hence; further its anti-virulent and anti-quorum activities were evaluated. Zingerone, besides decreasing swimming, swarming and twitching phenotypes of P. aeruginosa PAO1, reduced biofilm forming capacity and production of virulence factors including rhamnolipid, elastase, protease, pyocyanin, cell free and cell bound hemolysin (pquorum sensing signal molecules by clinical isolates of P. aeruginosa but also showed significant interference with the activation of QS reporter strains. To study the mechanism of blocking quorum sensing cascade, in silico analysis was carried out. Anti-QS activity was attributed to interference with the ligand receptor interaction of zingerone with QS receptors (TraR, LasR, RhlR and PqsR). Zingerone showed a good comparative docking score to respective autoinducer molecules which was even higher than that of vanillin, a proven anti-quorum sensing phytochemical. The results of the present study revealed the anti-quorum sensing activity of zingerone targeting ligand-receptor interaction, hence proposing zingerone as a suitable anti-virulent drug candidate against P. aeruginosa infections. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Communicative Silences: Forms and Functions

    Science.gov (United States)

    Bruneau, Thomas J.

    1973-01-01

    The nature of silence is discussed as an imposition of mind, as an interdependent signification ground for speech signs, as a relationship to mental time (as opposed to artificial time), and as it relates to sensation, perception and metaphorical movement. (Author)

  12. 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.

  13. 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.

  14. Breaching cultural silence: enhancing resilience among Ugandan ...

    African Journals Online (AJOL)

    Cultural silence is frequently the outcome of deep-seated taboos regarding adults talking to children about sex and death. This paper examines the impact of cultural silence on the resilience of children orphaned by AIDS in Uganda. Cultural silence is often linked with denial. This article explores the complexities of cultural ...

  15. Transcriptional Silencing of Retroviral Vectors

    DEFF Research Database (Denmark)

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

    1996-01-01

    Although retroviral vector systems have been found to efficiently transduce a variety of cell types in vitro, the use of vectors based on murine leukemia virus in preclinical models of somatic gene therapy has led to the identification of transcriptional silencing in vivo as an important problem....... 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...

  16. Posttranscriptional gene silencing in nuclei

    Science.gov (United States)

    Hoffer, Paul; Ivashuta, Sergey; Pontes, Olga; Vitins, Alexa; Pikaard, Craig; Mroczka, Andrew; Wagner, Nicholas; Voelker, Toni

    2011-01-01

    In plants, small interfering RNAs (siRNAs) with sequence homology to transcribed regions of genes can guide the sequence-specific degradation of corresponding mRNAs, leading to posttranscriptional gene silencing (PTGS). The current consensus is that siRNA-mediated PTGS occurs primarily in the cytoplasm where target mRNAs are localized and translated into proteins. However, expression of an inverted-repeat double-stranded RNA corresponding to the soybean FAD2-1A desaturase intron is sufficient to silence FAD2-1, implicating nuclear precursor mRNA (pre-mRNA) rather than cytosolic mRNA as the target of PTGS. Silencing FAD2-1 using intronic or 3′-UTR sequences does not affect transcription rates of the target genes but results in the strong reduction of target transcript levels in the nucleus. Moreover, siRNAs corresponding to pre-mRNA–specific sequences accumulate in the nucleus. In Arabidopsis, we find that two enzymes involved in PTGS, Dicer-like 4 and RNA-dependent RNA polymerase 6, are localized in the nucleus. Collectively, these results demonstrate that siRNA-directed RNA degradation can take place in the nucleus, suggesting the need for a more complex view of the subcellular compartmentation of PTGS in plants. PMID:21173264

  17. [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.

  18. 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.

  19. "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…

  20. Mechanisms of epigenetic silencing of the c21 gene in Y1 adrenocortical tumor cells.

    Science.gov (United States)

    Szyf, M; Slack, A D

    2000-11-01

    We utilized Y1 adrenocortical carcinoma cell line as a model system to dissect the events regulating epigenomic gene silencing in tumor cells. We show here that the chromatin structure of c21 gene is inactive in Y1 cells and that it could be reconfigured to an active form by either expressing antisense mRNA to DNA methyltransferase 1 (dnmt1) or an attenuator of Ras protooncogenic signaling hGAP. Surprisingly however, the known inducer of active chromatin structure the histone deacetylase inhibitor trichostatin A TSA fails to induce expression of c21. These results suggest that the primary cause of c21 gene silencing is independent of histone deacetylation. We present a model to explain the possible roles of the different components of the epigenome and the DNA methylation and demethylation machineries in silencing c21 gene expression.

  1. Epigenetic Silencing and Resistance to Imatinib Mesylate in CML

    National Research Council Canada - National Science Library

    Issa, Jean-Pierre

    2004-01-01

    ...). In this project, we are exploring the hypothesis that epigenetic silencing associated with promoter DNA methylation mediates resistance in selected cases, and that reversal of silencing by decitabine...

  2. Epigenetic Silencing and Resistance to Imatinib Mesylate in CML

    National Research Council Canada - National Science Library

    Issa, Jean-Pierre

    2005-01-01

    ...). In this project, we are exploring the hypothesis that epigenetic silencing associated with promoter DNA methylation mediates resistance in selected cases, and that reversal of silencing by decitabine...

  3. Epigenetic Silencing and Resistance to Imatinib Mesylate in CML

    National Research Council Canada - National Science Library

    Issa, Jean-Pierre

    2006-01-01

    ...). In this project we are exploring the hypothesis that epigenetic silencing associated with promoter DNA methylation mediates resistance in selected cases and that reversal of silencing by decitabine...

  4. Personalized gene silencing therapeutics for Huntington disease.

    Science.gov (United States)

    Kay, C; Skotte, N H; Southwell, A L; Hayden, M R

    2014-07-01

    Gene silencing offers a novel therapeutic strategy for dominant genetic disorders. In specific diseases, selective silencing of only one copy of a gene may be advantageous over non-selective silencing of both copies. Huntington disease (HD) is an autosomal dominant disorder caused by an expanded CAG trinucleotide repeat in the Huntingtin gene (HTT). Silencing both expanded and normal copies of HTT may be therapeutically beneficial, but preservation of normal HTT expression is preferred. Allele-specific methods can selectively silence the mutant HTT transcript by targeting either the expanded CAG repeat or single nucleotide polymorphisms (SNPs) in linkage disequilibrium with the expansion. Both approaches require personalized treatment strategies based on patient genotypes. We compare the prospect of safe treatment of HD by CAG- and SNP-specific silencing approaches and review HD population genetics used to guide target identification in the patient population. Clinical implementation of allele-specific HTT silencing faces challenges common to personalized genetic medicine, requiring novel solutions from clinical scientists and regulatory authorities. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. 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.

  6. Mannan-Binding Lectin-Associated Serine Protease 1/3 Cleavage of Pro-Factor D into Factor D In Vivo and Attenuation of Collagen Antibody-Induced Arthritis through Their Targeted Inhibition by RNA Interference-Mediated Gene Silencing

    Science.gov (United States)

    Banda, Nirmal K.; Acharya, Sumitra; Scheinman, Robert I.; Mehta, Gaurav; Coulombe, Marilyne; Takahashi, Minoru; Sekine, Hideharu; Thiel, Steffen; Fujita, Teizo; Holers, V Michael

    2016-01-01

    The complement system is proposed to play an important role in the pathogenesis of rheumatoid arthritis (RA). The complement system mannan-binding lectin associated serine proteases 1 and 3 (MASP-1/3) cleave proDf (inactive) into Df (active), but it is unknown where this cleavage occurs and whether inhibition of MASP-1/3 is a relevant therapeutic strategy for RA. We show herein that the cleavage of proDf into Df by MASP-1/3 can occur in the circulation and that inhibition of MASP-1/3 by gene silencing is sufficient to ameliorate collagen antibody-induced arthritis (CAIA) in mice. Specifically, to examine the cleavage of proDf into Df, MASP-1/3 producing Df−/− liver tissue (donor) was transplanted under the kidney capsule of MASP-1/3−/− (recipient) mice. Five weeks after the liver transplantation, cleaved Df was present in the circulation of MASP-1/3−/− mice. To determine the individual effects of MASP-1/3 and Df gene silencing on CAIA, mice were injected with scrambled, MASP-1/3 targeted, or Df targeted siRNAs. The mRNA levels for MASP-1 and 3 decreased in the liver to 62% and 58%, respectively, in mice injected with MASP-1/3 siRNAs, and Df mRNA decreased to 53% in the adipose tissue of mice injected with Df siRNAs; additionally, circulating MASP-1/3 and Df protein levels were decreased. In mice injected with both siRNAs the clinical disease activity, histopathologic injury scores, C3 deposition, and synovial macrophage/ neutrophil infiltration were significantly decreased. Thus MASP-1/3 is a new therapeutic target for the treatment of RA, likely through both direct effects on the LP and indirect through the AP. PMID:27707997

  7. 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.

  8. Titration and hysteresis in epigenetic chromatin silencing

    Science.gov (United States)

    Dayarian, Adel; Sengupta, Anirvan M.

    2013-06-01

    Epigenetic mechanisms of silencing via heritable chromatin modifications play a major role in gene regulation and cell fate specification. We consider a model of epigenetic chromatin silencing in budding yeast and study the bifurcation diagram and characterize the bistable and the monostable regimes. The main focus of this paper is to examine how the perturbations altering the activity of histone modifying enzymes affect the epigenetic states. We analyze the implications of having the total number of silencing proteins, given by the sum of proteins bound to the nucleosomes and the ones available in the ambient, to be constant. This constraint couples different regions of chromatin through the shared reservoir of ambient silencing proteins. We show that the response of the system to perturbations depends dramatically on the titration effect caused by the above constraint. In particular, for a certain range of overall abundance of silencing proteins, the hysteresis loop changes qualitatively with certain jump replaced by continuous merger of different states. In addition, we find a nonmonotonic dependence of gene expression on the rate of histone deacetylation activity of Sir2. We discuss how these qualitative predictions of our model could be compared with experimental studies of the yeast system under anti-silencing drugs.

  9. Titration and hysteresis in epigenetic chromatin silencing

    International Nuclear Information System (INIS)

    Dayarian, Adel; Sengupta, Anirvan M

    2013-01-01

    Epigenetic mechanisms of silencing via heritable chromatin modifications play a major role in gene regulation and cell fate specification. We consider a model of epigenetic chromatin silencing in budding yeast and study the bifurcation diagram and characterize the bistable and the monostable regimes. The main focus of this paper is to examine how the perturbations altering the activity of histone modifying enzymes affect the epigenetic states. We analyze the implications of having the total number of silencing proteins, given by the sum of proteins bound to the nucleosomes and the ones available in the ambient, to be constant. This constraint couples different regions of chromatin through the shared reservoir of ambient silencing proteins. We show that the response of the system to perturbations depends dramatically on the titration effect caused by the above constraint. In particular, for a certain range of overall abundance of silencing proteins, the hysteresis loop changes qualitatively with certain jump replaced by continuous merger of different states. In addition, we find a nonmonotonic dependence of gene expression on the rate of histone deacetylation activity of Sir2. We discuss how these qualitative predictions of our model could be compared with experimental studies of the yeast system under anti-silencing drugs. (paper)

  10. 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

  11. Spatiotemporal flicker detector model of motion silencing.

    Science.gov (United States)

    Choi, Lark Kwon; Bovik, Alan C; Cormack, Lawrence K

    2014-01-01

    Motion can impair the perception of other visual changes. Suchow and Alvarez (2011a, Current Biology, 21, 140-143) recently demonstrated a striking 'motion silencing' illusion, in which the salient changes among a group of objects' luminances (or colors, etc) appear to cease in the presence of large, coherent object motion. To understand why the visual system might be insensitive to changes in object luminances ('flicker') in the presence of object motion, we constructed similar stimuli and did a systematic spectral analysis of them. We conducted human psychophysical experiments to examine motion silencing as a function of stimulus velocity, flicker frequency, and spacing; and we created a simple filter-based model as a working hypothesis of motion silencing. From the results, we found that the threshold of silencing occurs when the log frequency of object replacement is roughly one quarter of the log flicker frequency (the mean slope is approximately 0.27). The dependence of silencing on object spacing may be explained as a phenomenon of temporal sampling of the stimuli by the visual system. Our proposed model successfully captures the psychophysical data over a wide range of velocities and flicker frequencies.

  12. 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....

  13. Active compressor engine silencer reduces exhaust noise

    International Nuclear Information System (INIS)

    Denenberg, J.N.; Miller, S.K.; Jay, M.A.

    1994-01-01

    An active industrial silencer on a compressor engine at a Tenneco Gas station has reduced low-frequency 'rumbling' noise by 8 dB during trials while lowering backpressure about 90$. This 8 dB reduction of the piston firing frequency corresponds to a more than 80% decrease in emitted acoustic power. The silencing unit, installed on one of six engines at the station near Eden, N.Y., continues in operation. Based on the results, the manufacturer is identifying additional compressor sites for further tests. This paper reviews this project

  14. “The Silence Itself is Enough of a Statement”: Unintended Consequences of Silence as an Awareness-Raising Strategy

    OpenAIRE

    Woolley, Susan W.

    2010-01-01

    The strategy of silence for voice, as seen in the Day of Silence, deploys silence in order to draw attention to the ways in which an individual or group has been silenced and to establish possibilities for voice. The Day of Silence is a nation-wide day of action aimed at addressing anti-LGBTQ bias and harassment in schools. This ethnographic study of a high school gay-straight alliance (GSA) club examines the unintended consequences of silence as an awareness-raising strategy during events ...

  15. Grafting on a Non-Transgenic Tolerant Tomato Variety Confers Resistance to the Infection of a Sw5-Breaking Strain of Tomato spotted wilt virus via RNA Silencing.

    Directory of Open Access Journals (Sweden)

    Roberta Spanò

    Full Text Available RNA silencing controls endogenous gene expression and drives defensive reactions against invasive nucleic acids like viruses. In plants, it has been demonstrated that RNA silencing can be transmitted through grafting between scions and silenced rootstocks to attenuate virus and viroid accumulation in the scions. This has been obtained mostly using transgenic plants, which may be a drawback in current agriculture. In the present study, we examined the dynamics of infection of a resistance-breaking strain of Tomato spotted wilt virus (RB-TSWV through the graft between an old Apulian (southern Italy tomato variety, denoted Sl-Ma, used as a rootstock and commercial tomato varieties used as scions. In tests with non-grafted plants, Sl-Ma showed resistance to the RB-TSWV infection as viral RNA accumulated at low levels and plants recovered from disease symptoms by 21 days post inoculation. The resistance trait was transmitted to the otherwise highly susceptible tomato genotypes grafted onto Sl-Ma. The results from the analysis of small RNAs hallmark genes involved in RNA silencing and virus-induced gene silencing suggest that RNA silencing is involved in the resistance showed by Sl-Ma against RB-TSWV and in scions grafted on this rootstock. The results from self-grafted susceptible tomato varieties suggest also that RNA silencing is enhanced by the graft itself. We can foresee interesting practical implications of the approach described in this paper.

  16. 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)

  17. Histone Methylation and Epigenetic Silencing in Breast Cancer

    National Research Council Canada - National Science Library

    Simon, Jeffrey A; Lange, Carol A

    2008-01-01

    .... EZH2 is a histone methyltransferase which modifies lysine-27 of histone H3 an epigenetic mark which is generally linked to gene silencing and is implicated in tumor suppressor silencing during breast cancer progression...

  18. 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.

  19. Mainstream Television, Adolescent Homosexuality, and Significant Silence.

    Science.gov (United States)

    Kielwasser, Alfred P.; Wolf, Michelle A.

    1992-01-01

    Argues that the symbolic annihilation of gay and lesbian youth exhibited by network television contributes to a dysfunctional isolation supported by the mutually reinforcing invisibility of homosexual adolescents on television and in the real world. Suggests that the spiral of silence also partially accounts for the inefficacy of oppositional…

  20. From talking to silence: a confessional journey

    OpenAIRE

    Heddon, D.; Howells, A.

    2011-01-01

    This article provides an account of work created by Adrian Howells over the duration of his AHRC Creative Fellowship. Howells provides a creator's perspective; Heddon, a spectator's perspective. Both chart the shift from confessional performances anchored around speech, to the use of silence as a way to engage intimate connections between performer and audience.

  1. 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

  2. Cucumber mosaic virus coat protein modulates the accumulation of 2b protein and antiviral silencing that causes symptom recovery in planta.

    Directory of Open Access Journals (Sweden)

    Xiao-Peng Zhang

    2017-07-01

    Full Text Available Shoot apical meristems (SAM are resistant to most plant viruses due to RNA silencing, which is restrained by viral suppressors of RNA silencing (VSRs to facilitate transient viral invasion of the SAM. In many cases chronic symptoms and long-term virus recovery occur, but the underlying mechanisms are poorly understood. Here, we found that wild-type Cucumber mosaic virus (CMVWT invaded the SAM transiently, but was subsequently eliminated from the meristems. Unexpectedly, a CMV mutant, designated CMVRA that harbors an alanine substitution in the N-terminal arginine-rich region of the coat protein (CP persistently invaded the SAM and resulted in visible reductions in apical dominance. Notably, the CMVWT virus elicited more potent antiviral silencing than CMVRA in newly emerging leaves of infected plants. However, both viruses caused severe symptoms with minimal antiviral silencing effects in the Arabidopsis mutants lacking host RNA-DEPENDENT RNA POLYMERASE 6 (RDR6 or SUPPRESSOR OF GENE SILENCING 3 (SGS3, indicating that CMVWT induced host RDR6/SGS3-dependent antiviral silencing. We also showed that reduced accumulation of the 2b protein is elicited in the CMVWT infection and consequently rescues potent antiviral RNA silencing. Indeed, co-infiltration assays showed that the suppression of posttranscriptional gene silencing mediated by 2b is more severely compromised by co-expression of CPWT than by CPRA. We further demonstrated that CPWT had high RNA binding activity leading to translation inhibition in wheat germ systems, and CPWT was associated with SGS3 into punctate granules in vivo. Thus, we propose that the RNAs bound and protected by CPWT possibly serve as templates of RDR6/SGS3 complexes for siRNA amplification. Together, these findings suggest that the CMV CP acts as a central hub that modulates antiviral silencing and VSRs activity, and mediates viral self-attenuation and long-term symptom recovery.

  3. Pressure surge attenuator

    Science.gov (United States)

    Christie, Alan M.; Snyder, Kurt I.

    1985-01-01

    A pressure surge attenuation system for pipes having a fluted region opposite crushable metal foam. As adapted for nuclear reactor vessels and heads, crushable metal foam is disposed to attenuate pressure surges.

  4. Break the silence: Let's talk about AIDS.

    Science.gov (United States)

    1999-10-11

    The organizers of the Confederation of East and Central Africa Football Associations¿ (CECAFA) Youth Tournament in Kenya will organize a campaign on AIDS prevention. ¿Break the Silence: Let¿s Talk About AIDS¿ is the campaign slogan, which will be used before, during, and after the 2-week football tournament. The campaign will involve an estimated 300 players and coaches and millions of fans who will attend, watch television, or listen to radios. AIDS prevention efforts linked to the tournament include: radio and television AIDS prevention spots featuring famous football players; campaign orientation and training in AIDS outreach and education for coaches and team managers; telephone hotlines for HIV/AIDS counseling through public phone booths and health information booths; AIDS information caravans to support community awareness rallies about AIDS prevention; and a minute of silence at the beginning of all matches to commemorate soccer heroes and other loved ones who have died of AIDS.

  5. Homology-dependent Gene Silencing in Paramecium

    Science.gov (United States)

    Ruiz, Françoise; Vayssié, Laurence; Klotz, Catherine; Sperling, Linda; Madeddu, Luisa

    1998-01-01

    Microinjection at high copy number of plasmids containing only the coding region of a gene into the Paramecium somatic macronucleus led to a marked reduction in the expression of the corresponding endogenous gene(s). The silencing effect, which is stably maintained throughout vegetative growth, has been observed for all Paramecium genes examined so far: a single-copy gene (ND7), as well as members of multigene families (centrin genes and trichocyst matrix protein genes) in which all closely related paralogous genes appeared to be affected. This phenomenon may be related to posttranscriptional gene silencing in transgenic plants and quelling in Neurospora and allows the efficient creation of specific mutant phenotypes thus providing a potentially powerful tool to study gene function in Paramecium. For the two multigene families that encode proteins that coassemble to build up complex subcellular structures the analysis presented herein provides the first experimental evidence that the members of these gene families are not functionally redundant. PMID:9529389

  6. 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. PMID:24401541

  7. 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.

  8. Chromosome 21-derived microRNAs provide an etiological basis for aberrant protein expression in human Down syndrome brains.

    Science.gov (United States)

    Kuhn, Donald E; Nuovo, Gerard J; Terry, Alvin V; Martin, Mickey M; Malana, Geraldine E; Sansom, Sarah E; Pleister, Adam P; Beck, Wayne D; Head, Elizabeth; Feldman, David S; Elton, Terry S

    2010-01-08

    Down syndrome (DS), or Trisomy 21, is the most common genetic cause of cognitive impairment and congenital heart defects in the human population. Bioinformatic annotation has established that human chromosome 21 (Hsa21) harbors five microRNA (miRNAs) genes: miR-99a, let-7c, miR-125b-2, miR-155, and miR-802. Our laboratory recently demonstrated that Hsa21-derived miRNAs are overexpressed in DS brain and heart specimens. The aim of this study was to identify important Hsa21-derived miRNA/mRNA target pairs that may play a role, in part, in mediating the DS phenotype. We demonstrate by luciferase/target mRNA 3'-untranslated region reporter assays, and gain- and loss-of-function experiments that miR-155 and -802 can regulate the expression of the predicted mRNA target, the methyl-CpG-binding protein (MeCP2). We also demonstrate that MeCP2 is underexpressed in DS brain specimens isolated from either humans or mice. We further demonstrate that, as a consequence of attenuated MeCP2 expression, transcriptionally activated and silenced MeCP2 target genes, CREB1/Creb1 and MEF2C/Mef2c, are also aberrantly expressed in these DS brain specimens. Finally, in vivo silencing of endogenous miR-155 or -802, by antagomir intra-ventricular injection, resulted in the normalization of MeCP2 and MeCP2 target gene expression. Taken together, these results suggest that improper repression of MeCP2, secondary to trisomic overexpression of Hsa21-derived miRNAs, may contribute, in part, to the abnormalities in the neurochemistry observed in the brains of DS individuals. Finally these results suggest that selective inactivation of Hsa21-derived miRNAs may provide a novel therapeutic tool in the treatment of DS.

  9. Controlling low frequency noise using a passive silencer

    Energy Technology Data Exchange (ETDEWEB)

    DeGagne, D.C.; Faszer, A.C. [Noise Solutions Inc., Calgary, AB (Canada)

    2009-07-01

    Nearly 85 per cent of all the oil and natural gas recovered in Canada comes from Alberta where noise emissions from energy facilities are regulated by the Energy Resources Conservation Board (ERCB) and the Alberta Utilities Commission (AUC) through Noise Control Directive D-038. Operators of energy facilities in Alberta must meet the Permissible Sound Level (PSL) established for industrial facilities that are established for receptor locations such as nearby residences. Despite efforts to manage noise, complaints from nearby residents continue to occur even if the facility is in compliance. This is because high and mid frequency components can decay or be absorbed by air and ground conditions leaving mostly low frequency noise (LFN) at the residence. This paper explored the significance of LFN and how some facility operators are dealing with this problem. The impacts of LFN can range from creating a sensation of pressure in the ear, disturbing normal conversation, to creating secondary vibrating effects within homes. If severe enough, it can also result in potential behavioural dysfunction such as task performance deterioration, sleep disturbance and headaches. In 2006, Noise Solutions Inc. was approached by Hunt Oil Company regarding the installation of a new compressor at their Caroline site. The proposal posed a serious noise problem for the community which requested that the new compressor unit be developed without any additional noise impact on the area. Noise Solutions Inc. used a multi-phased approach to develop the most effective LFN silencer using best practical technology and materials. In an effort to fully attenuate both the high frequency noise (dBA) and the low frequency noise (dBC) of the new compressor unit, Noise Solutions and Hunt Oil agreed that a significant level of sound-suppression would be necessary. The entire noise-suppression unit was specially designed to compensate for the sheer size of the compressor building. The first step to

  10. Veiled Word(s) – Sacred Silence

    DEFF Research Database (Denmark)

    Isar, Nicoletta

    2014-01-01

    This paper defines the Byzantine altar as a sacred space of participative performance in the mystery of the Eucharist – a paradigm of “timeless re-enactment of the Christian drama.” Reading a series of Byzantine ekphraseis, the paper addresses such concepts as inner vision (theoria), silent...... 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...

  11. Collaborative silence and some unguided prerogative utterances of ...

    African Journals Online (AJOL)

    This essay attempts to demystify the silence and non-prosecution syndrome surrounding unguided prerogative utterances of Nigerian leaders as a contemporary culture, which has continued to threaten the unity and stability of the country. In doing this, the silence and withdrawal of key Nigerian agencies, such as; the ...

  12. 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…

  13. 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…

  14. 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…

  15. 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

  16. Language and silence: persoonlike herinneringe aan Adam Small ...

    African Journals Online (AJOL)

    Owner

    En hy was self nooit kategories of dogmaties in sy denke of uitsprake nie. Die titel van my voordrag is “Language and silence: persoonlike herinneringe aan. 'n digter-intellektueel”. Dis Adam wat my as student voorgestel het aan George Steiner se “Language and Silence: Essays on Language, Literature and the Inhumane.

  17. Strategic Silence as a Tool of Political Communication: A Reflection ...

    African Journals Online (AJOL)

    The paper, therefore, recommended that politicians should be cautious in the use of strategic silence as a means of political communication in view of the nature of politics which calls for self- expression in the use of persuasion, clarification and conviction to win public support and sympathy. Maintaining silence when one is ...

  18. 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

  19. Cancelation and its simulation using Matlab according to active noise control case study of automotive noise silencer

    Science.gov (United States)

    Alfisyahrin; Isranuri, I.

    2018-02-01

    Active Noise Control is a technique to overcome noisy with noise or sound countered with sound in scientific terminology i.e signal countered with signals. This technique can be used to dampen relevant noise in accordance with the wishes of the engineering task and reducing automotive muffler noise to a minimum. Objective of this study is to develop a Active Noise Control which should cancel the noise of automotive Exhaust (Silencer) through Signal Processing Simulation methods. Noise generator of Active Noise Control is to make the opponent signal amplitude and frequency of the automotive noise. The steps are: Firstly, the noise of automotive silencer was measured to characterize the automotive noise that its amplitude and frequency which intended to be expressed. The opposed sound which having similar character with the signal source should be generated by signal function. A comparison between the data which has been completed with simulation calculations Fourier transform field data is data that has been captured on the muffler (noise silencer) Toyota Kijang Capsule assembly 2009. MATLAB is used to simulate how the signal processing noise generated by exhaust (silencer) using FFT. This opponent is inverted phase signal from the signal source 180° conducted by Instruments of Signal Noise Generators. The process of noise cancelation examined through simulation using computer software simulation. The result is obtained that attenuation of sound (noise cancellation) has a difference of 33.7%. This value is obtained from the comparison of the value of the signal source and the signal value of the opponent. So it can be concluded that the noisy signal can be attenuated by 33.7%.

  20. 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.

  1. 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.

  2. Dynamics of Chromatin Silencing at Telomeres: Deterministic and Stochastic Aspects

    Science.gov (United States)

    Apratim, Manjul; Dayarian, Adel; Sontag, Eduardo; Sengupta, Anirvan

    2012-02-01

    Epigenetic silencing modifications of are often associated with well-defined domains. We study potential mechanisms of formation of boundary of silenced regions. We specially focus on the possibility that some telomeric silencing boundaries are formed in a self-organized manner, as opposed to being defined by specific boundary elements. In particular, we examine systems where a titration-induced feedback can stabilize the boundary of the silenced region. A consequence of having multiple such boundaries is large stochastic cell-to-cell variation of boundary locations. We proceed to make an argument about the nature of the fall-off of the average silencing protein occupancy, coming from such variability, and test the predictions against HA-Sir3 ChIP-seq data from experiments performed on yeast.

  3. Silence on Shangri-La: Attenuation of Huygens acoustic signals suggests surface volatiles

    Science.gov (United States)

    Lorenz, Ralph D.; Leese, Mark R.; Hathi, Brijen; Zarnecki, John C.; Hagermann, Axel; Rosenberg, Phil; Towner, Martin C.; Garry, James; Svedhem, Håkan

    2014-01-01

    Objective. Characterize and understand acoustic instrument performance on the surface of Titan. Methods. The Huygens probe measured the speed of sound in Titan's atmosphere with a 1 MHz pulse time-of-flight transducer pair near the bottom of the vehicle. We examine the fraction of pulses correctly received as a function of time. Results. This system returned good data from about 11 km altitude, where the atmosphere became thick enough to effectively transmit the sound, down to the surface just before landing: these data have been analyzed previously. After an initial transient at landing, the instrument operated nominally for about 10 min, recording pulses much as during descent. The fraction of pulses detected then declined and the transmitted sound ceased to be detected altogether, despite no indication of instrument or probe configuration changes. Conclusions. The most likely explanation appears to be absorption of the signal by polyatomic gases with relaxation losses at the instrument frequency, such as ethane, acetylene and carbon dioxide. These vapors, detected independently by the GCMS instrument, were evolved from the surface material by the warmth leaking from the probe, and confirm the nature of the surface materials as 'damp' with a cocktail of volatile compounds. Some suggestions for future missions are considered. Practice implications. None.

  4. The Curious Silence of the Dog and Paul of Tarsus; Revisiting The Argument from Silence

    Directory of Open Access Journals (Sweden)

    Michael Gary Duncan

    2012-03-01

    Full Text Available In this essay I propose an interpretative and explanatory structure for the so-called argumentum ex silento, or argument from silence (henceforth referred to as the AFS. To this end, I explore two examples, namely, Sherlock Holmes’s oft-quoted notice of the “curious incident of the dog in the night-time” from Arthur Conan Doyle’s short story “Silver Blaze,” and the historical question of Paul of Tarsus’s silence on biographical details of the historical Jesus. Through these cases, I conclude that the AFS serves as a dialogical topos best evaluated and understood through the perceived authority of the arguer and the willingness of the audience to accept that authority, due to the “curious” nature of the negative evidence that the argument employed.

  5. The ethics of silence: Does conflict of interest explain employee silence?

    Science.gov (United States)

    Anderson, James

    2018-03-01

    Employee silence constitutes a significant threat to organizational success. This article argues that silence is a by-product of a structural Conflict of Interest (COI) between employees and their employers. This argument turns on the claim, also defended here, that employees are in a privileged position vis-à-vis knowledge of their work and that leaders-whether they recognize it or not-are dependent on their employees for reliable information about the work they are doing. Employee voice, therefore, is an organizational necessity. It is also a moral achievement as it involves risking one's personal interests for the sake of the organization. Leaders must take steps to mitigate COI and encourage employee voice; this article provides several strategies for doing exactly that.

  6. 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

  7. Virus-induced gene silencing in diverse maize lines using the Brome Mosaic virus-based silencing vector

    Science.gov (United States)

    Virus-induced gene silencing (VIGS) is a widely used tool for gene function studies in many plant species, though its use in monocots has been limited. Using a Brome mosaic virus (BMV) vector designed to silence the maize phytoene desaturase gene, a genetically diverse set of maize inbred lines was ...

  8. Landing gear noise attenuation

    Science.gov (United States)

    Moe, Jeffrey W. (Inventor); Whitmire, Julia (Inventor); Kwan, Hwa-Wan (Inventor); Abeysinghe, Amal (Inventor)

    2011-01-01

    A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can have a first position when the landing gear is in its deployed or down position, and a second position when the landing gear is in its up or stowed position. The noise attenuator may be an inflatable fairing that does not compromise limited space constraints associated with landing gear retraction and stowage. A truck fairing mounted under a truck beam can have a compliant edge to allow for non-destructive impingement of a deflected fire during certain conditions.

  9. Bioinformatics tools for achieving better gene silencing in plants.

    Science.gov (United States)

    Ahmed, Firoz; Dai, Xinbin; Zhao, Patrick Xuechun

    2015-01-01

    RNA interference (RNAi) is one of the most popular and effective molecular technologies for knocking down the expression of an individual gene of interest in living organisms. Yet the technology still faces the major issue of nonspecific gene silencing, which can compromise gene functional characterization and the interpretation of phenotypes associated with individual gene knockdown. Designing an effective and target-specific small interfering RNA (siRNA) for induction of RNAi is therefore the major challenge in RNAi-based gene silencing. A 'good' siRNA molecule must possess three key features: (a) the ability to specifically silence an individual gene of interest, (b) little or no effect on the expressions of unintended siRNA gene targets (off-target genes), and (c) no cell toxicity. Although several siRNA design and analysis algorithms have been developed, only a few of them are specifically focused on gene silencing in plants. Furthermore, current algorithms lack a comprehensive consideration of siRNA specificity, efficacy, and nontoxicity in siRNA design, mainly due to lack of integration of all known rules that govern different steps in the RNAi pathway. In this review, we first describe popular RNAi methods that have been used for gene silencing in plants and their serious limitations regarding gene-silencing potency and specificity. We then present novel, rationale-based strategies in combination with computational and experimental approaches to induce potent, specific, and nontoxic gene silencing in plants.

  10. Oriana: the voice and the silences

    Directory of Open Access Journals (Sweden)

    Mercedes Rosúa

    2007-09-01

    Full Text Available Commentators did their best to bury the late Oriana Fallaci’s ideas and books written since the 11 S under tons of praises to her previous works, and under deep silence or global discrediting her denunciation of Islamic fundamentalism and of terrorist blackmail and all its forms of getting a grip on Europe. Obituary notices avoided carefully the analysis of facts and data brought forward by Oriana in her three last books: The rage and the pride. The power of the reason and Oriana Fallaci’s inter- view with herself. The Apocalypse. But the italian journalist, who past away on 15th Sep- tember 2006, denounced substantiated facts, true dangers and a real collusion of wes- tern sectors-venal, corrupt, fainthearted and ignorant-with the strategy of penetration and manipulation of public opinion of an islamic movement who is the enemy of democracies, Civil Rights, freedom and the western systems of open society.Key words: Oriana Fallaci, Islamic fundamentalism, Defence freedom, Denun- ciation fear, Europe ́s surrender, Terrorism, Western censorship. 

  11. Breaking the Silence: Feminism and Post humanism

    Directory of Open Access Journals (Sweden)

    Debika Saha

    2015-10-01

    Full Text Available Postmodernism starts its journey by challenging the master narratives of metaphysics and philosophy. In this journey the narrative get replaced either by an emancipation from narratives that claim to possess eternal truth or by a turn to a kind of informative technology. But both the ways keep at their centre the process of “denaturing” or disassociating something of its natural qualities. This postmodernist turn has now taken a new form. The choice is not limited between the natural body and the culturally constructed body, but between different areas of bodily reconstruction bearing different social and cultural implications. As Spivak in her famous writing raises the question «Can the subaltern speak?» In fact, Spivak narrates how the marginalized, the less privileged depend upon the benevolence of the more privileged. To engage with the other means not only to talk, listen, learn or know about her but also to identify with her. There must be some ways for open dialogues that can diminish the effects of cultural dominance. The imperial silence should be broken.

  12. Evidence for gene silencing by endogenous DNA methylation

    Science.gov (United States)

    Holliday, Robin; Ho, Thu

    1998-01-01

    Transformed cells can spontaneously silence genes by de novo methylation, and it is generally assumed that this is due to DNA methyltransferase activity. We have tested the alternative hypothesis that gene silencing could be due to the uptake of 5-methyl-dCMP into DNA, via the di- and triphosphonucleotides. 5-Methyl-dCMP would be present in cells from the ongoing repair of DNA. We have isolated a strain of Chinese hamster ovary (CHO) cells, designated HAM−, which spontaneously silences two tested genes at a very high frequency. We have shown that this strain incorporates 5-[3H]methyldeoxycytidine into 5-methylcytosine and thymine in DNA. It also has low 5-methyl-dCMP deaminase activity. Another HAM+ strain has high deaminase activity and a very low frequency of gene silencing. The starting strain, CHO K1, has a phenotype intermediate between HAM− and HAM+. PMID:9671746

  13. Mutations in Ran system affected telomere silencing in Saccharomyces cerevisiae

    International Nuclear Information System (INIS)

    Hayashi, Naoyuki; Kobayashi, Masahiko; Shimizu, Hiroko; Yamamoto, Ken-ichi; Murakami, Seishi; Nishimoto, Takeharu

    2007-01-01

    The Ran GTPase system regulates the direction and timing of several cellular events, such as nuclear-cytosolic transport, centrosome formation, and nuclear envelope assembly in telophase. To gain insight into the Ran system's involvement in chromatin formation, we investigated gene silencing at the telomere in several mutants of the budding yeast Saccharomyces cerevisiae, which had defects in genes involved in the Ran system. A mutation of the RanGAP gene, rna1-1, caused reduced silencing at the telomere, and partial disruption of the nuclear Ran binding factor, yrb2-Δ2, increased this silencing. The reduced telomere silencing in rna1-1 cells was suppressed by a high dosage of the SIR3 gene or the SIT4 gene. Furthermore, hyperphosphorylated Sir3 protein accumulated in the rna1-1 mutant. These results suggest that RanGAP is required for the heterochromatin structure at the telomere in budding yeast

  14. Locus-specific ribosomal RNA gene silencing in nucleolar dominance.

    Directory of Open Access Journals (Sweden)

    Michelle S Lewis

    2007-08-01

    Full Text Available The silencing of one parental set of rRNA genes in a genetic hybrid is an epigenetic phenomenon known as nucleolar dominance. We showed previously that silencing is restricted to the nucleolus organizer regions (NORs, the loci where rRNA genes are tandemly arrayed, and does not spread to or from neighboring protein-coding genes. One hypothesis is that nucleolar dominance is the net result of hundreds of silencing events acting one rRNA gene at a time. A prediction of this hypothesis is that rRNA gene silencing should occur independent of chromosomal location. An alternative hypothesis is that the regulatory unit in nucleolar dominance is the NOR, rather than each individual rRNA gene, in which case NOR localization may be essential for rRNA gene silencing. To test these alternative hypotheses, we examined the fates of rRNA transgenes integrated at ectopic locations. The transgenes were accurately transcribed in all independent transgenic Arabidopsis thaliana lines tested, indicating that NOR localization is not required for rRNA gene expression. Upon crossing the transgenic A. thaliana lines as ovule parents with A. lyrata to form F1 hybrids, a new system for the study of nucleolar dominance, the endogenous rRNA genes located within the A. thaliana NORs are silenced. However, rRNA transgenes escaped silencing in multiple independent hybrids. Collectively, our data suggest that rRNA gene activation can occur in a gene-autonomous fashion, independent of chromosomal location, whereas rRNA gene silencing in nucleolar dominance is locus-dependent.

  15. Radiofrequency attenuator and method

    Science.gov (United States)

    Warner, Benjamin P [Los Alamos, NM; McCleskey, T Mark [Los Alamos, NM; Burrell, Anthony K [Los Alamos, NM; Agrawal, Anoop [Tucson, AZ; Hall, Simon B [Palmerston North, NZ

    2009-01-20

    Radiofrequency attenuator and method. The attenuator includes a pair of transparent windows. A chamber between the windows is filled with molten salt. Preferred molten salts include quarternary ammonium cations and fluorine-containing anions such as tetrafluoroborate (BF.sub.4.sup.-), hexafluorophosphate (PF.sub.6.sup.-), hexafluoroarsenate (AsF.sub.6.sup.-), trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Radicals or radical cations may be added to or electrochemically generated in the molten salt to enhance the RF attenuation.

  16. RNA silencing is resistant to low-temperature in grapevine.

    Directory of Open Access Journals (Sweden)

    Marjorie Romon

    Full Text Available RNA silencing is a natural defence mechanism against viruses in plants, and transgenes expressing viral RNA-derived sequences were previously shown to confer silencing-based enhanced resistance against the cognate virus in several species. However, RNA silencing was shown to dysfunction at low temperatures in several species, questioning the relevance of this strategy in perennial plants such as grapevines, which are often exposed to low temperatures during the winter season. Here, we show that inverted-repeat (IR constructs trigger a highly efficient silencing reaction in all somatic tissues in grapevines. Similarly to other plant species, IR-derived siRNAs trigger production of secondary transitive siRNAs. However, and in sharp contrast to other species tested to date where RNA silencing is hindered at low temperature, this process remained active in grapevine cultivated at 4°C. Consistently, siRNA levels remained steady in grapevines cultivated between 26°C and 4°C, whereas they are severely decreased in Arabidopsis grown at 15°C and almost undetectable at 4°C. Altogether, these results demonstrate that RNA silencing operates in grapevine in a conserved manner but is resistant to far lower temperatures than ever described in other species.

  17. 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.

  18. 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.

  19. Precedents and consequences of prosocial behaviors of voice and silence

    Directory of Open Access Journals (Sweden)

    Alicia Omar

    2015-09-01

    Full Text Available Prosocial behavior is that which that encourages solidarity and harmony in interpersonal relationships, and produce personal or collective benefits. Although early research on job prosociality was focused on the study of conventional behaviors such as help, courtesy and sportsmanship, the identification and operationalization of new dimensions is rapidly expanding this nomological network. Such is the case of prosocial voice and prosocial silence, recently introduced in the scientific literature. The aim of this study is to explore possible relationships between employee’s voice and employee’s silence, and their personality structure; and examine the role of interpersonal justice perceptions on such relationships. We worked with a sample of 316 employees- aged 37 years and holding a 4.2-year signority working at public and private companies in southern and central Rosario (Argentina. The subjects completed Colquitt’ Justice Organizational Scale, Eysenck Personality Questionnaire, and Van Dyne’s Prosocial Voice and Prosocial Silence Scales. Extraversion and neuroticism emerged as the strongest predictors of prosocial voice and prosocial silence, respectively. Interpersonal justice perceptions emerged as moderators of the ‘natural’ tendency of extraverted workers to engage in prosocial voice, and emotionally controlled workers to engage in prosocial silence. Such findings would indicate that the promotion of high levels of interpersonal justice on job contexts could help workers to engage in more prosocial behavior with positive effects for the organization. 

  20. RELATIONSHIP BETWEEN AFFECTIVE COMMITMENT ANDORGANIZATIONAL SILENCE: A CONCEPTUAL DISCUSSION

    Directory of Open Access Journals (Sweden)

    Fitnat Nazlı Sayğan

    2011-07-01

    Full Text Available In this study, the affective commitment that is oneof the components oforganizational commitment put forth by Allen and Meyer (Allen, Meyer 1996will be differentiated from the other commitment components. The importance ofcreating an emotional commitment to organizations will be examined and theorganizational factors needed to form organizational commitment will beinvestigated. Also, organizational silence is a situation that the company avoided.In the study, the reasons and the drawbacks of silence are focused on and thefactors that cause employees to remain silent are discussed.The aim of this study is intended to manifest the relationship of ‘organizationalsilence' with affective commitment’ which is one ofthe components of‘organizational commitment’ on the basis of literature. In this study, a negativecorrelation between affective commitment and organizational silence is suggested

  1. RNA silencing can explain chlorotic infection patterns on plant leaves

    Directory of Open Access Journals (Sweden)

    Hogeweg Paulien

    2008-11-01

    Full Text Available Abstract Background RNA silencing has been implicated in virus symptom development in plants. One common infection symptom in plants is the formation of chlorotic tissue in leaves. Chlorotic and healthy tissue co-occur on a single leaf and form patterns. It has been shown that virus levels in chlorotic tissue are high, while they are low in healthy tissue. Additionally, the presence of siRNAs is confined to the chlorotic spots and the boundaries between healthy and infected tissue. These results strongly indicate that the interaction between virus growth and RNA silencing plays a role in the formation of infection patterns on leaves. However, how RNA silencing leads to the intricate patterns is not known. Results Here we elucidate the mechanisms leading to infection patterns and the conditions which lead to the various patterns observed. We present a modeling approach in which we combine intra- and inter-cellular dynamics of RNA silencing and viral growth. We observe that, due to the spread of viruses and the RNA silencing response, parts of the tissue become infected while other parts remain healthy. As is observed in experiments high virus levels coincide with high levels of siRNAs, and siRNAs are also present in the boundaries between infected and healthy tissue. We study how single- and double-stranded cleavage by Dicer and amplification by RNA-dependent RNA polymerase can affect the patterns formed. Conclusion This work shows that RNA silencing and virus growth within a cell, and the local spread of virions and siRNAs between cells can explain the heterogeneous spread of virus in leaf tissue, and therewith the observed infection patterns in plants.

  2. Control algorithms for dynamic attenuators

    International Nuclear Information System (INIS)

    Hsieh, Scott S.; Pelc, Norbert J.

    2014-01-01

    Purpose: The authors describe algorithms to control dynamic attenuators in CT and compare their performance using simulated scans. Dynamic attenuators are prepatient beam shaping filters that modulate the distribution of x-ray fluence incident on the patient on a view-by-view basis. These attenuators can reduce dose while improving key image quality metrics such as peak or mean variance. In each view, the attenuator presents several degrees of freedom which may be individually adjusted. The total number of degrees of freedom across all views is very large, making many optimization techniques impractical. The authors develop a theory for optimally controlling these attenuators. Special attention is paid to a theoretically perfect attenuator which controls the fluence for each ray individually, but the authors also investigate and compare three other, practical attenuator designs which have been previously proposed: the piecewise-linear attenuator, the translating attenuator, and the double wedge attenuator. Methods: The authors pose and solve the optimization problems of minimizing the mean and peak variance subject to a fixed dose limit. For a perfect attenuator and mean variance minimization, this problem can be solved in simple, closed form. For other attenuator designs, the problem can be decomposed into separate problems for each view to greatly reduce the computational complexity. Peak variance minimization can be approximately solved using iterated, weighted mean variance (WMV) minimization. Also, the authors develop heuristics for the perfect and piecewise-linear attenuators which do not requirea priori knowledge of the patient anatomy. The authors compare these control algorithms on different types of dynamic attenuators using simulated raw data from forward projected DICOM files of a thorax and an abdomen. Results: The translating and double wedge attenuators reduce dose by an average of 30% relative to current techniques (bowtie filter with tube current

  3. Friction coefficient measurements of silencers on specialized duct tract

    Directory of Open Access Journals (Sweden)

    Sehnalek Stanislav

    2016-01-01

    Full Text Available This article describes test methods on air duct track in Laboratory of Environmental Engineering. It focuses on measurement of silencer parameter like is pressure loss coeffcient. Firstly, the paper describe the measurement apparatus with description of calculation method by standard ISO 7235 and energy equation. Then the paper presents three ways how to accomplish measurement because such way is not covered by procedure in standard. Then follows the evaluation of results of measurements on three types of silencer designed for HVAC applications. The article is concluded with discussion over measured data with outline for further research.

  4. Re-discovery of silence in pastoral care.

    Science.gov (United States)

    Moriichi, Shuji

    2009-01-01

    Pastoral care within the greater American cultural milieu strongly appraises the use of spoken words and tends to undervalue silence as a powerful and creative element for mutual connection with others and with God. In this essay the author proposes a "counter-cultural" adjustment in the perception of silence and its implications to the practice of, and theological understanding of, pastoral care. The author bases his theses on his own cross-cultural learning experiences, including his training in Clinical Pastoral Education (CPE), in the re-vitalization of ancient Christian wisdom, and in his current ministry to nursing home residents.

  5. Ribosomal Stalk Protein Silencing Partially Corrects the ΔF508-CFTR Functional Expression Defect.

    Directory of Open Access Journals (Sweden)

    Guido Veit

    2016-05-01

    Full Text Available The most common cystic fibrosis (CF causing mutation, deletion of phenylalanine 508 (ΔF508 or Phe508del, results in functional expression defect of the CF transmembrane conductance regulator (CFTR at the apical plasma membrane (PM of secretory epithelia, which is attributed to the degradation of the misfolded channel at the endoplasmic reticulum (ER. Deletion of phenylalanine 670 (ΔF670 in the yeast oligomycin resistance 1 gene (YOR1, an ABC transporter of Saccharomyces cerevisiae phenocopies the ΔF508-CFTR folding and trafficking defects. Genome-wide phenotypic (phenomic analysis of the Yor1-ΔF670 biogenesis identified several modifier genes of mRNA processing and translation, which conferred oligomycin resistance to yeast. Silencing of orthologues of these candidate genes enhanced the ΔF508-CFTR functional expression at the apical PM in human CF bronchial epithelia. Although knockdown of RPL12, a component of the ribosomal stalk, attenuated the translational elongation rate, it increased the folding efficiency as well as the conformational stability of the ΔF508-CFTR, manifesting in 3-fold augmented PM density and function of the mutant. Combination of RPL12 knockdown with the corrector drug, VX-809 (lumacaftor restored the mutant function to ~50% of the wild-type channel in primary CFTRΔF508/ΔF508 human bronchial epithelia. These results and the observation that silencing of other ribosomal stalk proteins partially rescue the loss-of-function phenotype of ΔF508-CFTR suggest that the ribosomal stalk modulates the folding efficiency of the mutant and is a potential therapeutic target for correction of the ΔF508-CFTR folding defect.

  6. Silencing miR-146a influences B cells and ameliorates experimental autoimmune myasthenia gravis.

    Science.gov (United States)

    Zhang, JunMei; Jia, Ge; Liu, Qun; Hu, Jue; Yan, Mei; Yang, BaiFeng; Yang, Huan; Zhou, WenBin; Li, Jing

    2015-01-01

    MicroRNAs have been shown to be important regulators of immune homeostasis as patients with aberrant microRNA expression appeared to be more susceptible to autoimmune diseases. We recently found that miR-146a was up-regulated in activated B cells in response to rat acetylcholine receptor (AChR) α-subunit 97-116 peptide, and this up-regulation was significantly attenuated by AntagomiR-146a. Our data also demonstrated that silencing miR-146a with its inhibitor AntagomiR-146a effectively ameliorated clinical myasthenic symptoms in mice with ongoing experimental autoimmune myasthenia gravis. Furthermore, multiple defects were observed after miR-146a was knocked down in B cells, including decreased anti-R97-116 antibody production and class switching, reduced numbers of plasma cells, memory B cells and B-1 cells, and weakened activation of B cells. Previously, miR-146a has been identified as a nuclear factor-κB-dependent gene and predicted to base pair with the tumour necrosis factor receptor-associated factor 6 (TRAF6) and interleukin-1 receptor-associated kinase 1 (IRAK1) genes to regulate the immune response. However, our study proved that miR-146a inhibition had no effect on the expression of TRAF6 and IRAK1 in B cells. This result suggests that the function of miR-146a in B cells does not involve these two target molecules. We conclude that silencing miR-146a exerts its therapeutic effects by influencing the B-cell functions that contribute to the autoimmune pathogenesis of myasthenia gravis. © 2014 John Wiley & Sons Ltd.

  7. An Abundant Class of Non-coding DNA Can Prevent Stochastic Gene Silencing in the C. elegans Germline

    DEFF Research Database (Denmark)

    Frøkjær-Jensen, Christian; Jain, Nimit; Hansen, Loren

    2016-01-01

    Cells benefit from silencing foreign genetic elements but must simultaneously avoid inactivating endogenous genes. Although chromatin modifications and RNAs contribute to maintenance of silenced states, the establishment of silenced regions will inevitably reflect underlying DNA sequence and/or s...

  8. Small RNA binding is a common strategy to suppress RNA silencing by several viral suppressors

    Science.gov (United States)

    Lakatos, Lóránt; Csorba, Tibor; Pantaleo, Vitantonio; Chapman, Elisabeth J; Carrington, James C; Liu, Yu-Ping; Dolja, Valerian V; Calvino, Lourdes Fernández; López-Moya, Juan José; Burgyán, József

    2006-01-01

    RNA silencing is an evolutionarily conserved system that functions as an antiviral mechanism in higher plants and insects. To counteract RNA silencing, viruses express silencing suppressors that interfere with both siRNA- and microRNA-guided silencing pathways. We used comparative in vitro and in vivo approaches to analyse the molecular mechanism of suppression by three well-studied silencing suppressors. We found that silencing suppressors p19, p21 and HC-Pro each inhibit the intermediate step of RNA silencing via binding to siRNAs, although the molecular features required for duplex siRNA binding differ among the three proteins. None of the suppressors affected the activity of preassembled RISC complexes. In contrast, each suppressor uniformly inhibited the siRNA-initiated RISC assembly pathway by preventing RNA silencing initiator complex formation. PMID:16724105

  9. Suppressors of RNA silencing encoded by tomato leaf curl ...

    Indian Academy of Sciences (India)

    2013-01-06

    Jan 6, 2013 ... step in the RNA-silencing pathway that occurs after siRNA production (Zrachya et al. 2007). Geminiviruses (family Geminiviridae) are a diverse group of plant viruses with circular single-stranded DNA genomes that are composed of one or two components of 2700–. 3000 bp length which are encapsidated ...

  10. Organizational Justice As a Predictor of Organizational Silence

    Science.gov (United States)

    Tan, Çetin

    2014-01-01

    In this study, relation between teachers' perception for organizational justice and their organizational silence was examined. Sample of this study consists of 300 teachers who work at elementary schools in Siirt. Relational Scanning model was utilized in performance of this study. In this study, Organizational Justice Scale and Organizational…

  11. For the Sake of Silence | Kearney | Current Writing: Text and ...

    African Journals Online (AJOL)

    The Order of Cistercians of the Strict Observance – better known as “Trappists” after their famous monastery, Notre Dame de la Trappe – is the strictest and most ascetic Order in the Catholic Church. In addition to vows of poverty, chastity and obedience taken by all religious, Trappists bind themselves to silence and stability ...

  12. Survivors' Voices Breaking the Silence: Owning the Past.

    Science.gov (United States)

    Benton, Carol L.

    For the adult survivor of incest, the evolution from victim to survivor occurs in complex and creative ways. Often journal writing can be a means of exposing and exploring past abuse. The process of journal writing is special in that it allows the adult survivor to break the silence and shame imposed by the perpetrator while remaining essentially…

  13. Bureaucratic Constructions of Sexual Diversity: "Sensitive", "Controversial" and Silencing

    Science.gov (United States)

    Ullman, Jacqueline; Ferfolja, Tania

    2015-01-01

    National research illustrates the high degree of discrimination that prevails against lesbian, gay, bisexual, transgender and queer (LGBTQ) students resulting in diminished educational outcomes, both academic and social. This phenomenon is influenced by the prevalence of whole-school silences around LGBTQ topics in many Australian schools. This…

  14. Identification of a maize chlorotic dwarf virus silencing suppressor protein.

    Science.gov (United States)

    Stewart, Lucy R; Jarugula, Sridhar; Zhao, Yujing; Qu, Feng; Marty, DeeMarie

    2017-04-01

    Maize chlorotic dwarf virus (MCDV), a member of the genus Waikavirus, family Secoviridae, has a 11784 nt (+)ssRNA genome that encodes a 389kDa proteolytically processed polyprotein. We show that the N-terminal 78kDa polyprotein (R78) of MCDV acts as a suppressor of RNA silencing in a well-established assay system. We further demonstrate that R78 is cleaved by the viral 3C-like protease into 51 and 27kDa proteins (p51 and p27), and that p51 is responsible for silencing suppressor activity. Silencing suppressor activity of R78 is conserved in three divergent MCDV strains (MCDV-Severe, MCDV-M1, and MCDV-Tennessee), as well as the waikavirus Bellflower vein chlorosis virus, but was not detected for orthologous protein of Rice tungro spherical virus (RTSV-A) or the similarly-positioned protein from the sequivirus Parsnip yellow fleck virus (PYFV). This is the first identification of a virus suppressor of RNA silencing encoded by a waikavirus. Copyright © 2017. Published by Elsevier Inc.

  15. The effects of thinking in silence on creativity and innovation

    NARCIS (Netherlands)

    de Vet, A.J.

    2007-01-01

    This dissertation consists of three empirical studies on the effects of thinking in silence on creativity and innovation. In these studies I use a social psychology and cognitive psychology lens to study creativity and innovation at the individual and at the team level of analysis, using randomized

  16. RNAi-based silencing of genes encoding the vacuolar- ATPase ...

    African Journals Online (AJOL)

    RNAi-based silencing of genes encoding the vacuolar- ATPase subunits a and c in pink bollworm (Pectinophora gossypiella). Ahmed M. A. Mohammed. Abstract. RNA interference is a post- transcriptional gene regulation mechanism that is predominantly found in eukaryotic organisms. RNAi demonstrated a successful ...

  17. 47 CFR 80.304 - Watch requirement during silence periods.

    Science.gov (United States)

    2010-10-01

    ....304 Section 80.304 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE MARITIME SERVICES Safety Watch Requirements and Procedures Ship Station Safety Watches § 80.304 Watch requirement during silence periods. Each ship station operating on...

  18. Silence is Golden: The Lack of Direction on Compensation for ...

    African Journals Online (AJOL)

    Silence is Golden: The Lack of Direction on Compensation for Expropriation in the 2011 Green Paper on Land Reform. ... Frustrated at the slow pace of land reform, the ruling party is starting to indicate that the state will in future rely on its expropriation powers to acquire such land. Section 25 of the Constitution makes it ...

  19. Maternal Silences: Motherhood and Voluntary Childlessness in Contemporary Christianity

    Directory of Open Access Journals (Sweden)

    Dawn Llewellyn

    2016-06-01

    Full Text Available In Christianity, there is an ideology of motherhood that pervades scripture, ritual, and doctrine, yet there is an academic silence that means relatively little space has been given to motherhood and mothering, and even less to voluntary childlessness, from a faith perspective. By drawing on qualitative in-depth interviews with Christian women living in Britain, narrating their experiences of motherhood and voluntary childlessness, I suggest there are also lived maternal silences encountered by women in contemporary Christianity. There is a maternal expectation produced through church teaching, liturgy and culture that constructs women as ‘maternal bodies’ (Gatrell 2008; this silences and marginalises women from articulating their complex relationship with religion, motherhood, and childlessness in ways that challenge their spiritual development. However, this article also introduces the everyday and intentional tactics women employ to disrupt the maternal expectation, and hereby interrupt the maternal silence.

  20. Shame and Silence | Janz | South African Journal of Philosophy

    African Journals Online (AJOL)

    Samantha Vice's proposal on how to live in 'this strange place' of contemporary South Africa, includes an appeal to the concepts of shame and silence. In this paper, I use Emmanuel Levinas and Giorgio Agamben to move the discussion of shame from a moral to an existential question. The issue is not about how one ...

  1. Identification of a maize chlorotic dwarf virus silencing suppressor protein

    Science.gov (United States)

    Maize chlorotic dwarf virus (MCDV), a member of the genus Waikavirus, family Secoviridae, has a 11784 nt (+)ssRNA genome that encodes a 389 kDa proteolytically processed polyprotein. We show that an N-terminal 78kDa polyprotein (R78) has silencing suppressor activity, that it is cleaved by the viral...

  2. Relationship between Organizational Mobbing and Silence Behavior among Teachers

    Science.gov (United States)

    Hüsrevsahi, Selda Polat

    2015-01-01

    This study mainly aims to investigate the correlation between teachers' exposure to mobbing in their workplaces and their display of the act of silence. This study is based on a survey design where data from 312 teachers were collected and analyzed using correlation and regression analyses. Specifically, "The Structure and Dimensions of…

  3. Inhibition of tobacco axillary bud differentiation by silencing CUP ...

    African Journals Online (AJOL)

    Yomi

    2012-02-23

    Feb 23, 2012 ... exhibited some important phenotypes, such as leaf fusion, leaf curl and incomplete leaf. CUC3 in N. tabacum was silenced successfully by RNA interference (RNAi), which .... 0.1 mg NAA L-1 and 1.0 mg BAP L-1 was used as co-culture medium. Co-culture medium with hygromycin B 50 mg hygromycin.

  4. Studies of the silencing of Baculovirus DNA binding protein

    NARCIS (Netherlands)

    Quadt, I.; Lent, van J.W.M.; Knebel-Morsdorf, D.

    2007-01-01

    Baculovirus DNA binding protein (DBP) binds preferentially single-stranded DNA in vitro and colocalizes with viral DNA replication sites. Here, its putative role as viral replication factor has been addressed by RNA interference. Silencing of DBP in Autographa californica multiple

  5. Tacit Authorization : A Legal Solution for Administrative Silence

    NARCIS (Netherlands)

    Hoogstra, Nicole; de Graaf, K.J.

    2016-01-01

    This article discusses one of the current legal instruments to stimulate timely decision-making by administrative authorities, namely the ‘Lex silencio positivo’ or the ‘Silence is Consent’ rule. Tacit authorization prescribes that the license sought by the applicant will be granted automatically if

  6. Suppressors of RNA silencing encoded by tomato leaf curl ...

    Indian Academy of Sciences (India)

    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.

  7. 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.

  8. 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 obj...

  9. Silencing of HMGA2 promotes apoptosis and inhibits migration and ...

    Indian Academy of Sciences (India)

    2016-04-05

    Apr 5, 2016 ... Silencing of HMGA2 promotes apoptosis and inhibits migration and invasion of prostate cancer cells. ZHAN SHI, DING WU, RUN TANG, XIANG LI, RENFU CHEN, SONG XUE, CHENGJING ZHANG and XIAOQING SUN*. Department of Urology, The Affiliated Hospital of Xuzhou Medical College,. Xuzhou ...

  10. RNAi-based silencing of genes encoding the vacuolar- ATPase ...

    African Journals Online (AJOL)

    2016-11-09

    Nov 9, 2016 ... Spodoptera exigua larval development by silencing chitin synthase gene with RNA interference. Bull. Entomol. Res. 98:613-619. Dow JAT (1999). The Multifunctional Drosophila melanogaster V-. ATPase is encoded by a multigene family. J. Bioenerg. Biomembr. 31:75-83. Fire A, Xu SQ, Montgomery MK, ...

  11. Breaking the Silence Surrounding Mental Health on Campus

    Science.gov (United States)

    Roper, Larry D.

    2013-01-01

    Mentally ill students are able to participate in higher education at unprecedented rates. While colleges and universities have been responsive to the therapeutic needs, we have failed to successfully create supportive campus climates. Campus leaders are challenged to demonstrate ethical leadership that breaks the silence and confronts the stigma…

  12. MGMT gene silencing and benefit from temozolomide in glioblastoma

    NARCIS (Netherlands)

    Hegi, ME; Diserens, A; Gorlia, T; Hamou, M; de Tribolet, N; Weller, M; Kros, JM; Hainfellner, JA; Mason, W; Mariani, L; Bromberg, JEC; Hau, P; Mirimanoff, RO; Cairncross, JG; Janzer, RC; Stupp, R

    2005-01-01

    BACKGROUND: Epigenetic silencing of the MGMT (O(sup 6)-methylguanine-DNA methyltransferase) DNA-repair gene by promoter methylation compromises DNA repair and has been associated with longer survival in patients with glioblastoma who receive alkylating agents. METHODS: We tested the relationship

  13. Suppressors of RNA silencing encoded by tomato leaf curl ...

    Indian Academy of Sciences (India)

    2013-01-06

    Jan 6, 2013 ... satellite DNA β which are predicted to function as silencing suppressors. In the present study suppressor function ... of plant viruses with circular single-stranded DNA genomes that are composed of one or two components of ..... 1 2 3 4 5 6 7 8 9 10 11 12 13 14 M. Figure 4. Southern blot analysis of DNA ...

  14. The code of silence: Revisiting South African police integrity | Ivkovic ...

    African Journals Online (AJOL)

    ... results provide further evidence of the presence of the code of silence covering various forms of police misconduct. At least one quarter of the respondents would protect a fellow officer who verbally abused citizens, covered up police driving under the influence (DUI) accident, accepted gratuities, or failed to react to graffiti.

  15. 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.

  16. Marie Nimier, au cœur du silence

    Directory of Open Access Journals (Sweden)

    Joëlle Papillon

    2012-01-01

    Full Text Available Dans La Reine du silence, Marie Nimier se confronte à la figure de son père, l’écrivain Roger Nimier, mort lorsqu’elle avait cinq ans. Elle y montre le poids qui pèse sur l’enfant d’écrivain, mais aussi celui de l’héritage du secret familial et de l’injonction au silence. La difficulté de l’élaboration de son récit de filiation se révèle dans les constants recommencements et reformulations, qui constituent la marque de la tension angoissante entre l’obligation de dire et celle de taire. In La Reine du silence, Marie Nimier confronts her father’s memory – the writer Roger Nimier, who died when she was five years old. The novel describes the burden of being a writer’s child, along with that of inheriting family secrets and submitting to a code of silence. The difficulty of recounting her relationship with her late father is evidenced by the narrator’s numerous “false starts” and her constant rewritings. The hesitant nature of the narration captures an anguish born of two irreconcilable obligations : the need to put things into words and the pressure to remain silent.

  17. Assessment of RNAi-induced silencing in banana (Musa spp.).

    Science.gov (United States)

    Dang, Tuong Vi T; Windelinckx, Saskia; Henry, Isabelle M; De Coninck, Barbara; Cammue, Bruno P A; Swennen, Rony; Remy, Serge

    2014-09-18

    In plants, RNA- based gene silencing mediated by small RNAs functions at the transcriptional or post-transcriptional level to negatively regulate target genes, repetitive sequences, viral RNAs and/or transposon elements. Post-transcriptional gene silencing (PTGS) or the RNA interference (RNAi) approach has been achieved in a wide range of plant species for inhibiting the expression of target genes by generating double-stranded RNA (dsRNA). However, to our knowledge, successful RNAi-application to knock-down endogenous genes has not been reported in the important staple food crop banana. Using embryogenic cell suspension (ECS) transformed with ß-glucuronidase (GUS) as a model system, we assessed silencing of gusAINT using three intron-spliced hairpin RNA (ihpRNA) constructs containing gusAINT sequences of 299-nt, 26-nt and 19-nt, respectively. Their silencing potential was analysed in 2 different experimental set-ups. In the first, Agrobacterium-mediated co-transformation of banana ECS with a gusAINT containing vector and an ihpRNA construct resulted in a significantly reduced GUS enzyme activity 6-8 days after co-cultivation with either the 299-nt and 19-nt ihpRNA vectors. In the second approach, these ihpRNA constructs were transferred to stable GUS-expressing ECS and their silencing potential was evaluated in the regenerated in vitro plants. In comparison to control plants, transgenic plants transformed with the 299-nt gusAINT targeting sequence showed a 4.5 fold down-regulated gusA mRNA expression level, while GUS enzyme activity was reduced by 9 fold. Histochemical staining of plant tissues confirmed these findings. Northern blotting used to detect the expression of siRNA in the 299-nt ihpRNA vector transgenic in vitro plants revealed a negative relationship between siRNA expression and GUS enzyme activity. In contrast, no reduction in GUS activity or GUS mRNA expression occurred in the regenerated lines transformed with either of the two gusAINT oligo target

  18. "I Don't Want to Hear That!": Legitimating Whiteness through Silence in Schools

    Science.gov (United States)

    Castagno, Angelina E.

    2008-01-01

    In this article, I examine the ways in which silences around race contribute to the maintenance and legitimation of Whiteness. Drawing on ethnographic data from two demographically different schools, I highlight patterns of racially coded language, teacher silence, silencing students' race talk, and the conflating of culture with race, equality…

  19. Eloquent silences: A musical and lexical analysis of conversation between oncologists and their patients.

    Science.gov (United States)

    Bartels, Josef; Rodenbach, Rachel; Ciesinski, Katherine; Gramling, Robert; Fiscella, Kevin; Epstein, Ronald

    2016-10-01

    Silences in doctor-patient communication can be "connectional" and communicative, in contrast to silences that indicate awkwardness or distraction. Musical and lexical analyses can identify and characterize connectional silences in consultations between oncologists and patients. Two medical students and a professor of voice screened all 1211 silences over 2s in length from 124 oncology office visits. We developed a "strength of connection" taxonomy and examined ten connectional silences for lexical and musical features including pitch, volume, and speaker turn-taking rhythm. We identified connectional silences with good reliability. Typical dialog rhythms surrounding connectional silences are characterized by relatively equal turn lengths and frequent short vocalizations. We found no pattern of volume and pitch variability around these silences. Connectional silences occurred in a wide variety of lexical contexts. Particular patterns of dialog rhythm mark connectional silences. Exploring structures of connectional silence extends our understanding of the audio-linguistic conditions that mark patient-clinician connection. Communicating with an awareness of pitch, rhythm, and silence - in addition to lexical content - can facilitate shared understanding and emotional connection. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  20. RNA-mediated gene silencing of superoxide dismutase (bcsod1) in Botrytis cinerea

    NARCIS (Netherlands)

    Patel, R.M.; Kan, van J.A.L.; Bailey, A.M.; Foster, G.D.

    2008-01-01

    Gene silencing is a powerful tool utilized for identification of gene function and analysis in plants, animals, and fungi. Here, we report the silencing of superoxide dismutase (bcsod1) in Botrytis cinerea through sense and antisense-mediated silencing mechanisms. Because superoxide dismutase (SOD)

  1. Simultaneous Silencing of Xylanase Genes in Botrytis cinerea

    Directory of Open Access Journals (Sweden)

    Néstor García

    2017-12-01

    Full Text Available The endo-β-1,4-xylanase BcXyn11A is one of several plant cell-wall degrading enzymes that the phytopathogenic fungus Botrytis cinerea secretes during interaction with its hosts. In addition to its enzymatic activity, this protein also acts as an elicitor of the defense response in plants and has been identified as a virulence factor. In the present work, other four endoxylanase coding genes (Bcxyn11B, Bcxyn11C, Bcxyn10A, and Bcxyn10B were identified in the B. cinerea genome and the expression of all five genes was analyzed by Q-RT- PCR in vitro and in planta. A cross-regulation between xylanase genes was identified analyzing their expression pattern in the ΔBcxyn11A mutant strain and a putative BcXyn11A-dependt induction of Bcxyn10B gene was found. In addition, multiple knockdown strains were obtained for the five endoxylanase genes by transformation of B. cinerea with a chimeric DNA construct composed of 50-nt sequences from the target genes. The silencing of each xylanase gene was analyzed in axenic cultures and during infection and the results showed that the efficiency of the multiple silencing depends on the growth conditions and on the cross-regulation between them. Although the simultaneous silencing of the five genes was observed by Q-RT-PCR when the silenced strains were grown on medium supplemented with tomato extract, the endoxylanase activity measured in the supernatants was reduced only by 40%. Unexpectedly, the silenced strains overexpressed the Bcxyn11A and Bcxyn11C genes during the infection of tomato leaves, making difficult the analysis of the role of the endo-β-1,4-xylanases in the virulence of the fungus.

  2. Effect of tyrosine hydroxylase gene silencing in CD4+ T lymphocytes on differentiation and function of helper T cells.

    Science.gov (United States)

    Liu, Yan; Huang, Yan; Wang, Xiao-Qin; Peng, Yu-Ping; Qiu, Yi-Hua

    2012-01-01

    We explored effect of gene silencing of tyrosine hydroxylase (TH), a rate-limiting enzyme for synthesis of catecholamines (CAs), in CD4+ T cells on differentiation and function of helper T (Th) cells to provide more evidence for functional significance of lymphocyte-derived CAs. CD4+ T lymphocytes were isolated and purified from the mesenteric lymph nodes of mice. Recombinant TH miRNA expression vector (pcDNA6.2-GW/EmGFPmiR-TH) was constructed and transfected into concanavalin A (Con A)-activated CD4+ T lymphocytes using nucleofection technology. After incubated for 48 h, these cells were detected for TH gene and protein expression and CA content. Simultaneously, percentage of interferon-γ (IFN-γ)- and interleukin-4 (IL-4)-producing cells and levels of IL-2, IFN-γ, tumor necrosis factor (TNF), IL-4 and IL-5 in culture supernatants of Con A-stimulated CD4+ T cells were examined by flow cytometric analysis. CD4+ T lymphocytes with TH RNAi expressed less TH mRNA and protein and synthesized less CAs including norepinephrine, epinephrine and dopamine than control cells with mock transfection. The silencing of TH gene in CD4+ T lymphocytes reduced percentage of IL-4-producing cells and elevated ratio of IFN-γ-producing cells to IL-4-producing cells, although it did not alter proportion of IFN-γ-producing cells. The Th1 cytokines, IL-2, IFN-γ and TNF, were increased, but the Th2 cytokines, IL-4 and IL-5, were decreased in the culture supernatants of Con A-stimulated CD4+ T lymphocytes that were transfected with TH miRNA. TH gene silencing attenuates TH expression and CA synthesis in CD4+ T lymphocytes and promotes polarization of differentiation and function towards Th1 cells.

  3. Differential effects of two-pore channel protein 1 and 2 silencing in MDA-MB-468 breast cancer cells.

    Science.gov (United States)

    Jahidin, Aisyah H; Stewart, Teneale A; Thompson, Erik W; Roberts-Thomson, Sarah J; Monteith, Gregory R

    2016-09-02

    Two-pore channel proteins, TPC1 and TPC2, are calcium permeable ion channels found localized to the membranes of endolysosomal calcium stores. There is increasing interest in the role of TPC-mediated intracellular signaling in various pathologies; however their role in breast cancer has not been extensively evaluated. TPC1 and TPC2 mRNA was present in all non-tumorigenic and tumorigenic breast cell lines assessed. Silencing of TPC2 but not TPC1 attenuated epidermal growth factor-induced vimentin expression in MDA-MB-468 breast cancer cells. This effect was not due to a general inhibition of epithelial to mesenchymal transition (EMT) as TPC2 silencing had no effect on epidermal growth factor (EGF)-induced changes on E-cadherin expression. TPC1 and TPC2 were also shown to differentially regulate cyclopiazonic acid (CPA)-mediated changes in cytosolic free Ca(2+). These findings indicate potential differential regulation of signaling processes by TPC1 and TPC2 in breast cancer cells. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Toward a science of silence: The consequences of leaving a memory unsaid

    DEFF Research Database (Denmark)

    Stone, Charles; Coman, Alin; Brown, Adam

    2012-01-01

    Silence about the past permeates acts of remembering, with marked mnemonic consequences. Mnemonic silence—the absence of expressing a memory—is public in nature and is embedded within communicative acts, such as conversations. As such, silence has the potential to affect both speakers—the source...... the silence is intentional or unintentional, and whether the silenced memory is related or unrelated to the memories emerging in a conversation. These factors appear to be critical when considering the mnemonic consequences. Moreover, the influence of silence on memory varies between speaker and listener...

  5. 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

  6. [An analysis of "silence" in public opinion about public works].

    Science.gov (United States)

    Fujii, Satoshi

    2007-06-01

    An Internet survey targeting at from 200 to 500 samples in every prefecture in Japan (n=15,316) was conducted in order to analyze the expression of attitudes or silence regarding public works. The data indicated those who had different attitudes from the perceived public attitude were likely to express their attitudes, those whose attitude was neutral were not likely to express it, and those with positive attitudes were likely to express more than those with negative attitudes. The tendency that those with positive attitudes were more likely to express them than those with negative attitudes decreased as the residential population increased. Those with positive attitudes in Tokyo kept "silence" regarding their attitudes, similar to those with neutral attitudes. Analysis regarding the attitudes in different prefectures indicated that attitudes toward public works were positively related to the yearly public stake in the prefecture.

  7. cDNA libraries for virus-induced gene silencing.

    Science.gov (United States)

    Todd, Andrea T; Liu, Enwu; Page, Jonathan E

    2010-01-01

    Virus-induced gene silencing (VIGS) exploits endogenous plant antiviral defense mechanisms to posttranscriptionally silence the expression of targeted plant genes. VIGS is quick and relatively easy to perform and therefore serves as a powerful tool for high-throughput functional genomics in plants. Combined with the use of subtractive cDNA libraries for generating a collection of VIGS-ready cDNA inserts, VIGS can be utilized to screen a large number of genes to determine phenotypes resulting from the knockdown/knockout of gene function. Taking into account the optimal insert design for VIGS, we describe a methodology for producing VIGS-ready cDNA libraries enriched for inserts relevant to the biological process of interest.

  8. Bacterial Cellular Engineering by Genome Editing and Gene Silencing

    Directory of Open Access Journals (Sweden)

    Nobutaka Nakashima

    2014-02-01

    Full Text Available Genome editing is an important technology for bacterial cellular engineering, which is commonly conducted by homologous recombination-based procedures, including gene knockout (disruption, knock-in (insertion, and allelic exchange. In addition, some new recombination-independent approaches have emerged that utilize catalytic RNAs, artificial nucleases, nucleic acid analogs, and peptide nucleic acids. Apart from these methods, which directly modify the genomic structure, an alternative approach is to conditionally modify the gene expression profile at the posttranscriptional level without altering the genomes. This is performed by expressing antisense RNAs to knock down (silence target mRNAs in vivo. This review describes the features and recent advances on methods used in genomic engineering and silencing technologies that are advantageously used for bacterial cellular engineering.

  9. The great silence science and philosophy of Fermi's paradox

    CERN Document Server

    Cirkovic, Milan M

    2018-01-01

    The Great Silence explores the multifaceted problem named after the great Italian physicist Enrico Fermi and his legendary 1950 lunchtime question "Where is everybody?" In many respects, Fermi's paradox is the richest and the most challenging problem for the entire field of astrobiology and the Search for ExtraTerrestrial Intelligence (SETI) studies. This book shows how Fermi's paradox is intricately connected with many fields of learning, technology, arts, and even everyday life. It aims to establish the strongest possible version of the problem, to dispel many related confusions, obfuscations, and prejudices, as well as to offer a novel point of entry to the many solutions proposed in existing literature. Cirkovic argues that any evolutionary worldview cannot avoid resolving the Great Silence problem in one guise or another.

  10. Optical silencing of C. elegans cells with arch proton pump.

    Directory of Open Access Journals (Sweden)

    Ayako Okazaki

    Full Text Available BACKGROUND: Optogenetic techniques using light-driven ion channels or ion pumps for controlling excitable cells have greatly facilitated the investigation of nervous systems in vivo. A model organism, C. elegans, with its small transparent body and well-characterized neural circuits, is especially suitable for optogenetic analyses. METHODOLOGY/PRINCIPAL FINDINGS: We describe the application of archaerhodopsin-3 (Arch, a recently reported optical neuronal silencer, to C. elegans. Arch::GFP expressed either in all neurons or body wall muscles of the entire body by means of transgenes were localized, at least partially, to the cell membrane without adverse effects, and caused locomotory paralysis of worms when illuminated by green light (550 nm. Pan-neuronal expression of Arch endowed worms with quick and sustained responsiveness to such light. Worms reliably responded to repeated periods of illumination and non-illumination, and remained paralyzed under continuous illumination for 30 seconds. Worms expressing Arch in different subsets of motor neurons exhibited distinct defects in the locomotory behavior under green light: selective silencing of A-type motor neurons affected backward movement while silencing of B-type motor neurons affected forward movement more severely. Our experiments using a heat-shock-mediated induction system also indicate that Arch becomes fully functional only 12 hours after induction and remains functional for more than 24 hour. CONCLUSIONS/SGNIFICANCE: Arch can be used for silencing neurons and muscles, and may be a useful alternative to currently widely used halorhodopsin (NpHR in optogenetic studies of C. elegans.

  11. Hush… : The Dangers of Silence in Academic Libraries

    Directory of Open Access Journals (Sweden)

    Jessica Schomberg

    2017-04-01

    Full Text Available In Brief This article critiques the idea that civility rhetoric decreases workplace bullying or discrimination. We use Critical Discourse Analysis (CDA to do a rhetorical analysis of a campus-wide civility campaign in contrast with literature about civility in libraries. To combat discrimination and bullying, we need to be attentive to systemic power dynamics and to rhetoric designed to enforce compliance and conformity. We conclude with recommendations about how to raise our voices instead of silencing our peers.

  12. Hypoxia Silences Retrotrapezoid Nucleus Respiratory Chemoreceptors via Alkalosis

    OpenAIRE

    Basting, Tyler M.; Burke, Peter G.R.; Kanbar, Roy; Viar, Kenneth E.; Stornetta, Daniel S.; Stornetta, Ruth L.; Guyenet, Patrice G.

    2015-01-01

    In conscious mammals, hypoxia or hypercapnia stimulates breathing while theoretically exerting opposite effects on central respiratory chemoreceptors (CRCs). We tested this theory by examining how hypoxia and hypercapnia change the activity of the retrotrapezoid nucleus (RTN), a putative CRC and chemoreflex integrator. Archaerhodopsin-(Arch)-transduced RTN neurons were reversibly silenced by light in anesthetized rats. We bilaterally transduced RTN and nearby C1 neurons with Arch (PRSx8-ArchT...

  13. ORGANIZATIONAL SILENCE: SUATU PENGHAMBAT DALAM MEWUJUDKAN KREATIFITAS ORGANISASIONAL

    OpenAIRE

    Berta Bekti Retnawati

    2016-01-01

    There are powerful forces in many organzations that cause widespread withholding of information about potential problems or issues by employess, this collective-level phenomenon as ‘organizational silence’. One significant effect of organizational silence relates to lack of organizational creativity.There are five major organizational factors that enhance creativity in a work environment: organizational climate, leadership style, organizational culture, resources and skills, the structure and...

  14. Developing Gene Silencing for the Study and Treatment of Dystonia

    Science.gov (United States)

    2017-12-01

    that this is possible but using cells growing in a dish in the laboratory, not in living animals. In this project, we aim to answer several specific... important therapeutic implication of these experiments is that either the striatum is not the primary site of dysfunction in DYT1, or that the molecular...1 AWARD NUMBER: W81XWH-14-1-0282 TITLE: Developing Gene Silencing for the Study and Treatment of Dystonia PRINCIPAL INVESTIGATOR: Pedro

  15. Another Piece of the "Silence in PBL" Puzzle: Students' Explanations of Dominance and Quietness as Complementary Group Roles

    Science.gov (United States)

    Skinner, Vicki J.; Braunack-Mayer, Annette; Winning, Tracey A.

    2016-01-01

    A problem-based learning (PBL) assumption is that silence is incompatible with collaborative learning. Although sociocultural studies have reinterpreted silence as collaborative, we must understand how silence occurs in PBL groups. This essay presents students' explanations of dominance, leadership, and silence as PBL group roles. An ethnographic…

  16. RNAi-Mediated Specific Gene Silencing as a Tool for the Discovery of New Drug Targets in Giardia lamblia; Evaluation Using the NADH Oxidase Gene

    Directory of Open Access Journals (Sweden)

    Jaime Marcial-Quino

    2017-11-01

    Full Text Available The microaerophilic protozoan Giardia lamblia is the agent causing giardiasis, an intestinal parasitosis of worldwide distribution. Different pharmacotherapies have been employed against giardiasis; however, side effects in the host and reports of drug resistant strains generate the need to develop new strategies that identify novel biological targets for drug design. To support this requirement, we have designed and evaluated a vector containing a cassette for the synthesis of double-stranded RNA (dsRNA, which can silence expression of a target gene through the RNA interference (RNAi pathway. Small silencing RNAs were detected and quantified in transformants expressing dsRNA by a stem-loop RT-qPCR approach. The results showed that, in transformants expressing dsRNA of 100–200 base pairs, the level of NADHox mRNA was reduced by around 30%, concomitant with a decrease in enzyme activity and a reduction in the number of trophozoites with respect to the wild type strain, indicating that NADHox is indeed an important enzyme for Giardia viability. These results suggest that it is possible to induce the G. lamblia RNAi machinery for attenuating the expression of genes encoding proteins of interest. We propose that our silencing strategy can be used to identify new potential drug targets, knocking down genes encoding different structural proteins and enzymes from a wide variety of metabolic pathways.

  17. RNAi-Mediated Specific Gene Silencing as a Tool for the Discovery of New Drug Targets in Giardia lamblia; Evaluation Using the NADH Oxidase Gene

    Science.gov (United States)

    Marcial-Quino, Jaime; Rufino-González, Yadira; Sierra-Palacios, Edgar; Vanoye-Carlo, America; González-Valdez, Abigail; Torres-Arroyo, Angélica; Oria-Hernández, Jesús; Reyes-Vivas, Horacio

    2017-01-01

    The microaerophilic protozoan Giardia lamblia is the agent causing giardiasis, an intestinal parasitosis of worldwide distribution. Different pharmacotherapies have been employed against giardiasis; however, side effects in the host and reports of drug resistant strains generate the need to develop new strategies that identify novel biological targets for drug design. To support this requirement, we have designed and evaluated a vector containing a cassette for the synthesis of double-stranded RNA (dsRNA), which can silence expression of a target gene through the RNA interference (RNAi) pathway. Small silencing RNAs were detected and quantified in transformants expressing dsRNA by a stem-loop RT-qPCR approach. The results showed that, in transformants expressing dsRNA of 100–200 base pairs, the level of NADHox mRNA was reduced by around 30%, concomitant with a decrease in enzyme activity and a reduction in the number of trophozoites with respect to the wild type strain, indicating that NADHox is indeed an important enzyme for Giardia viability. These results suggest that it is possible to induce the G. lamblia RNAi machinery for attenuating the expression of genes encoding proteins of interest. We propose that our silencing strategy can be used to identify new potential drug targets, knocking down genes encoding different structural proteins and enzymes from a wide variety of metabolic pathways. PMID:29099754

  18. The Application of Coconut Fiber as Dissipative Silencer

    Science.gov (United States)

    Madlan, M. A.; Ghazali, M. I.; Zaman, I.; Kasron, M. Z.; Ying, T. C.

    2017-01-01

    Heat ventilation air conditioning system (HVAC) is one of the ducting systems that broadly applied in the building. There are HVAC silencers in the market, however the sound absorptive material commonly used is mineral wool. In this research study, a sound absorptive material made of coconut fiber was tested to identify its performance as a potential replacement of green material for ducting silencer. The experiment was carried out in a testing apparatus that follows the BS EN ISO 11691:2009 standard. Different configurations of sound absorptive material and contents of coconut fiber were investigated in the study. The trend of insertion loss at 1/3 octave frequency was identified where at frequency below 3000Hz, the insertion loss of dissipative silencer is observed high at certain frequency with a very narrow range. At 3000Hz, the insertion loss of 4dB to 6dB is constant until 4000Hz and drops until 5000Hz before it increases again steadily up to 13dB at 10000Hz. A similar trend was observed for different configuration of sound absorptive material. Despite the configuration different, the outcome shows that the insertion loss is increasing with higher content of coconut fiber.

  19. Epigenetic silencing of tumor suppressor genes: Paradigms, puzzles, and potential.

    Science.gov (United States)

    Kazanets, Anna; Shorstova, Tatiana; Hilmi, Khalid; Marques, Maud; Witcher, Michael

    2016-04-01

    Cancer constitutes a set of diseases with heterogeneous molecular pathologies. However, there are a number of universal aberrations common to all cancers, one of these being the epigenetic silencing of tumor suppressor genes (TSGs). The silencing of TSGs is thought to be an early, driving event in the oncogenic process. With this in consideration, great efforts have been made to develop small molecules aimed at the restoration of TSGs in order to limit tumor cell proliferation and survival. However, the molecular forces that drive the broad epigenetic reprogramming and transcriptional repression of these genes remain ill-defined. Undoubtedly, understanding the molecular underpinnings of transcriptionally silenced TSGs will aid us in our ability to reactivate these key anti-cancer targets. Here, we describe what we consider to be the five most logical molecular mechanisms that may account for this widely observed phenomenon: 1) ablation of transcription factor binding, 2) overexpression of DNA methyltransferases, 3) disruption of CTCF binding, 4) elevation of EZH2 activity, 5) aberrant expression of long non-coding RNAs. The strengths and weaknesses of each proposed mechanism is highlighted, followed by an overview of clinical efforts to target these processes. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  20. Silencing Deafness: Displacing Disability in the Nineteenth Century

    Directory of Open Access Journals (Sweden)

    Esme Cleall

    2015-03-01

    Full Text Available This article traces the way in which the language of displacement and silence were used in nineteenth-century discussions of deafness and connects this tendency to the marginalised place deaf experience occupies historically. Throughout the nineteenth century, a period which saw the consolidation of ‘the deaf and dumb’ as a social category, the word ‘forgetting’ crept into numerous discussions of deafness by both deaf and hearing commentators. Some, such as the educationalist Alexander Graeme Bell, were overt in their desire to forget deafness, demanding disability was ‘bred out’ and deaf culture condemned to the forgotten past. Others used the term ambivalently and sometimes metaphorically discussing the deaf as ‘forgotten’ by society, and ‘children of silence’. Some even pleaded that people who were deaf were not forgotten. But, though varied, the use of the imagery of forgetting and silence to evoke deafness is recurrent, and may, therefore, be seen to reveal something about how deaf experience can be approached as a displacement where deafness was spatially and imaginatively marginalised. I argue that one of the consequences of the conceptual framing of deafness through the language of forgetting was actively to silence deafness and to neutralise the idea that disability should be marginal and could be forgotten.

  1. Epigenetic silencing of CYP24 in the tumor microenvironment

    Science.gov (United States)

    Johnson, Candace S.; Chung, Ivy; Trump, Donald L.

    2010-01-01

    Calcitriol (1,25 dihydroxycholecalciferol) has significant antitumor activity in vitro and in vivo in a number of tumor model systems. We developed a system for isolation of fresh endothelial cells from tumors and Matrigel environments which demonstrate that CYP24, the catabolic enzyme involved in vitamin D signaling, is epigenetically silenced selectively in tumor-derived endothelial cells (TDEC). TDEC maintain phenotypic characteristics which are distinct from endothelial cells isolated from normal tissues and from Matrigel plugs (MDEC). In TDEC, calcitriol induces G0/G1 arrest, modulates p27 and p21, and induces apoptotic cell death and decreases P-Erk and P-Akt. In contrast, endothelial cells isolated from normal tissues and MDEC are unresponsive to calcitriol-mediated anti-proliferative effects despite intact signaling through the vitamin D receptor (VDR). In TDEC, which is sensitive to calcitriol, the CYP24 promoter is hypermethylated in two CpG island regions located at the 5′end; this hypermethylation may contribute to gene silencing of CYP24. The extent of methylation in these two regions is significantly less in MDEC. Lastly, treatment of TDEC with a DNA methyltransferase inhibitor restores calcitriol-mediated induction of CYP24 and resistance to calcitriol. These data suggest that epigenetic silencing of CYP24 modulates cellular responses to calcitriol. PMID:20304059

  2. Multi-gene epigenetic silencing of tumor suppressor genes in T-cell lymphoma cells; delayed expression of the p16 protein upon reversal of the silencing

    DEFF Research Database (Denmark)

    Nagasawa, T; Zhang, Q; Raghunath, P N

    2006-01-01

    )-expressing T-cell lymphomas. p16 gene was epigenetically silenced in all but one of the 10 malignant T-cell lines examined, p15 gene silenced in roughly half of the lines, and p14 was the least frequently affected. Extensive methylation of the p16 promoter was seen in six out of 10 cutaneous T-cell lymphoma...... promoter demethylation and required up to 3 weeks to occur, seemingly reflecting late activation of the p16 gene. These findings indicate that epigenetic silencing affects in T-cell malignancies, often simultaneously, several tumor suppressor genes that impact on key cell functions. The observed...... differential silencing of p16 and p14, and to a lesser degree p15 gene, indicates that the silencing is governed by precise, promoter region-specific mechanisms. The study provides also further rationale for treatment of at least some types of T-cell lymphomas with DNA methyltransferase inhibitors to target...

  3. Chromosome 21-derived MicroRNAs Provide an Etiological Basis for Aberrant Protein Expression in Human Down Syndrome Brains*

    Science.gov (United States)

    Kuhn, Donald E.; Nuovo, Gerard J.; Terry, Alvin V.; Martin, Mickey M.; Malana, Geraldine E.; Sansom, Sarah E.; Pleister, Adam P.; Beck, Wayne D.; Head, Elizabeth; Feldman, David S.; Elton, Terry S.

    2010-01-01

    Down syndrome (DS), or Trisomy 21, is the most common genetic cause of cognitive impairment and congenital heart defects in the human population. Bioinformatic annotation has established that human chromosome 21 (Hsa21) harbors five microRNA (miRNAs) genes: miR-99a, let-7c, miR-125b-2, miR-155, and miR-802. Our laboratory recently demonstrated that Hsa21-derived miRNAs are overexpressed in DS brain and heart specimens. The aim of this study was to identify important Hsa21-derived miRNA/mRNA target pairs that may play a role, in part, in mediating the DS phenotype. We demonstrate by luciferase/target mRNA 3′-untranslated region reporter assays, and gain- and loss-of-function experiments that miR-155 and -802 can regulate the expression of the predicted mRNA target, the methyl-CpG-binding protein (MeCP2). We also demonstrate that MeCP2 is underexpressed in DS brain specimens isolated from either humans or mice. We further demonstrate that, as a consequence of attenuated MeCP2 expression, transcriptionally activated and silenced MeCP2 target genes, CREB1/Creb1 and MEF2C/Mef2c, are also aberrantly expressed in these DS brain specimens. Finally, in vivo silencing of endogenous miR-155 or -802, by antagomir intra-ventricular injection, resulted in the normalization of MeCP2 and MeCP2 target gene expression. Taken together, these results suggest that improper repression of MeCP2, secondary to trisomic overexpression of Hsa21-derived miRNAs, may contribute, in part, to the abnormalities in the neurochemistry observed in the brains of DS individuals. Finally these results suggest that selective inactivation of Hsa21-derived miRNAs may provide a novel therapeutic tool in the treatment of DS. PMID:19897480

  4. Mimic Phosphorylation of a βC1 Protein Encoded by TYLCCNB Impairs Its Functions as a Viral Suppressor of RNA Silencing and a Symptom Determinant.

    Science.gov (United States)

    Zhong, Xueting; Wang, Zhan Qi; Xiao, Ruyuan; Cao, Linge; Wang, Yaqin; Xie, Yan; Zhou, Xueping

    2017-08-15

    Phosphorylation of the βC1 protein encoded by the betasatellite of tomato yellow leaf curl China virus (TYLCCNB-βC1) by SNF1-related protein kinase 1 (SnRK1) plays a critical role in defense of host plants against geminivirus infection in Nicotiana benthamiana However, how phosphorylation of TYLCCNB-βC1 impacts its pathogenic functions during viral infection remains elusive. In this study, we identified two additional tyrosine residues in TYLCCNB-βC1 that are phosphorylated by SnRK1. The effects of TYLCCNB-βC1 phosphorylation on its functions as a viral suppressor of RNA silencing (VSR) and a symptom determinant were investigated via phosphorylation mimic mutants in N. benthamiana plants. Mutations that mimic phosphorylation of TYLCCNB-βC1 at tyrosine 5 and tyrosine 110 attenuated disease symptoms during viral infection. The phosphorylation mimics weakened the ability of TYLCCNB-βC1 to reverse transcriptional gene silencing and to suppress posttranscriptional gene silencing and abolished its interaction with N. benthamiana ASYMMETRIC LEAVES 1 in N. benthamiana leaves. The mimic phosphorylation of TYLCCNB-βC1 had no impact on its protein stability, subcellular localization, or self-association. Our data establish an inhibitory effect of phosphorylation of TYLCCNB-βC1 on its pathogenic functions as a VSR and a symptom determinant and provide a mechanistic explanation of how SnRK1 functions as a host defense factor. IMPORTANCE Tomato yellow leaf curl China virus (TYLCCNV), which causes a severe yellow leaf curl disease in China, is a monopartite geminivirus associated with the betasatellite (TYLCCNB). TYLCCNB encodes a single pathogenicity protein, βC1 (TYLCCNB-βC1), which functions as both a viral suppressor of RNA silencing (VSR) and a symptom determinant. Here, we show that mimicking phosphorylation of TYLCCNB-βC1 weakens its ability to reverse transcriptional gene silencing, to suppress posttranscriptional gene silencing, and to interact with N

  5. 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. © 2015 BSPP AND JOHN WILEY & SONS LTD.

  6. 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

  7. 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.

  8. Silencing of GPNMB by siRNA Inhibits the Formation of Melanosomes in Melanocytes in a MITF-Independent Fashion

    Science.gov (United States)

    Zhu, Cansheng; Yuan, Xiaoying; Li, Dongguang; Gu, Weijie; Ma, Huimin; Xie, Xin; Gao, Tianwen

    2012-01-01

    Background Melanosomes are specialized membrane-surrounded organelles, which are involved in the synthesis, storage and transport of melanin. Glycoprotein (transmembrane) non-metastatic melanoma protein b (GPNMB), a melanosome-specific structural protein, shares significant amino acid sequence homology with Pmel-17. Proteomic analysis demonstrated that GPNMB is present in all stages (I-IV) of melanosomes. However, little is known about the role of GPNMB in melanosomes. Methodology/Principal Findings Using real-time quantitative PCR, Western blotting and immunofluorescence analysis, we demonstrated that the expression of GPNMB in PIG1 melanocytes was up-regulated by ultraviolet B (UVB) radiation. Transmission electron microscopy analysis showed that the total number of melanosomes in PIG1 melanocytes was sharply reduced by GPNMB-siRNA transfection. Simultaneously, the expression levels of tyrosinase (Tyr), tyrosinase related protein 1 (Trp1), Pmel17/gp100 and ocular albinism type 1 protein (OA1) were all significantly attenuated. But the expression of microphthalmia-associated transcription factor (MITF) was up-regulated. Intriguingly, in GPNMB silenced PIG1 melanocytes, UVB radiation sharply reduced MITF expression. Conclusion Our present work revealed that the GPNMB was critical for the formation of melanosomes. And GPNMB expression down-regulation attenuated melanosome formation in a MITF-independent fashion. PMID:22912767

  9. Lactate dehydrogenase A silencing in IDH mutant gliomas.

    Science.gov (United States)

    Chesnelong, Charles; Chaumeil, Myriam M; Blough, Michael D; Al-Najjar, Mohammad; Stechishin, Owen D; Chan, Jennifer A; Pieper, Russell O; Ronen, Sabrina M; Weiss, Samuel; Luchman, H Artee; Cairncross, J Gregory

    2014-05-01

    Mutations of the isocitrate dehydrogenase 1 and 2 gene (IDH1/2) were initially thought to enhance cancer cell survival and proliferation by promoting the Warburg effect. However, recent experimental data have shown that production of 2-hydroxyglutarate by IDH mutant cells promotes hypoxia-inducible factor (HIF)1α degradation and, by doing so, may have unexpected metabolic effects. We used human glioma tissues and derived brain tumor stem cells (BTSCs) to study the expression of HIF1α target genes in IDH mutant ((mt)) and IDH wild-type ((wt)) tumors. Focusing thereafter on the major glycolytic enzyme, lactate dehydrogenase A (LDHA), we used standard molecular methods and pyrosequencing-based DNA methylation analysis to identify mechanisms by which LDHA expression was regulated in human gliomas. We found that HIF1α-responsive genes, including many essential for glycolysis (SLC2A1, PDK1, LDHA, SLC16A3), were underexpressed in IDH(mt) gliomas and/or derived BTSCs. We then demonstrated that LDHA was silenced in IDH(mt) derived BTSCs, including those that did not retain the mutant IDH1 allele (mIDH(wt)), matched BTSC xenografts, and parental glioma tissues. Silencing of LDHA was associated with increased methylation of the LDHA promoter, as was ectopic expression of mutant IDH1 in immortalized human astrocytes. Furthermore, in a search of The Cancer Genome Atlas, we found low expression and high methylation of LDHA in IDH(mt) glioblastomas. To our knowledge, this is the first demonstration of downregulation of LDHA in cancer. Although unexpected findings, silencing of LDHA and downregulation of several other glycolysis essential genes raise the intriguing possibility that IDH(mt) gliomas have limited glycolytic capacity, which may contribute to their slow growth and better prognosis.

  10. Exon silencing by UAGG motifs in response to neuronal excitation.

    Directory of Open Access Journals (Sweden)

    Ping An

    2007-02-01

    Full Text Available Alternative pre-mRNA splicing plays fundamental roles in neurons by generating functional diversity in proteins associated with the communication and connectivity of the synapse. The CI cassette of the NMDA R1 receptor is one of a variety of exons that show an increase in exon skipping in response to cell excitation, but the molecular nature of this splicing responsiveness is not yet understood. Here we investigate the molecular basis for the induced changes in splicing of the CI cassette exon in primary rat cortical cultures in response to KCl-induced depolarization using an expression assay with a tight neuron-specific readout. In this system, exon silencing in response to neuronal excitation was mediated by multiple UAGG-type silencing motifs, and transfer of the motifs to a constitutive exon conferred a similar responsiveness by gain of function. Biochemical analysis of protein binding to UAGG motifs in extracts prepared from treated and mock-treated cortical cultures showed an increase in nuclear hnRNP A1-RNA binding activity in parallel with excitation. Evidence for the role of the NMDA receptor and calcium signaling in the induced splicing response was shown by the use of specific antagonists, as well as cell-permeable inhibitors of signaling pathways. Finally, a wider role for exon-skipping responsiveness is shown to involve additional exons with UAGG-related silencing motifs, and transcripts involved in synaptic functions. These results suggest that, at the post-transcriptional level, excitable exons such as the CI cassette may be involved in strategies by which neurons mount adaptive responses to hyperstimulation.

  11. Epigenetic silencing may aid evolution by gene duplication.

    Science.gov (United States)

    Rodin, Sergei N; Riggs, Arthur D

    2003-06-01

    Gene duplication is commonly regarded as the main evolutionary path toward the gain of a new function. However, even with gene duplication, there is a loss-versus-gain dilemma: most newly born duplicates degrade to pseudogenes, since degenerative mutations are much more frequent than advantageous ones. Thus, something additional seems to be needed to shift the loss versus gain equilibrium toward functional divergence. We suggest that epigenetic silencing of duplicates might play this role in evolution. This study began when we noticed in a previous publication (Lynch M, Conery JS [2000] Science 291:1151-1155) that the frequency of functional young gene duplicates is higher in organisms that have cytosine methylation (H. sapiens, M. musculus, and A. thaliana) than in organisms that do not have methylated genomes (S. cerevisiae, D. melanogaster, and C. elegans). We find that genome data analysis confirms the likelihood of much more efficient functional divergence of gene duplicates in mammals and plants than in yeast, nematode, and fly. We have also extended the classic model of gene duplication, in which newly duplicated genes have exactly the same expression pattern, to the case when they are epigenetically silenced in a tissue- and/or developmental stage-complementary manner. This exposes each of the duplicates to negative selection, thus protecting from "pseudogenization." Our analysis indicates that this kind of silencing (i) enhances evolution of duplicated genes to new functions, particularly in small populations, (ii) is quite consistent with the subfunctionalization model when degenerative but complementary mutations affect different subfunctions of the gene, and (iii) furthermore, may actually cooperate with the DDC (duplication-degeneration-complementation) process.

  12. miR-34a Silences c-SRC to Attenuate Tumor Growth in Triple-Negative Breast Cancer.

    Science.gov (United States)

    Adams, Brian D; Wali, Vikram B; Cheng, Christopher J; Inukai, Sachi; Booth, Carmen J; Agarwal, Seema; Rimm, David L; Győrffy, Balázs; Santarpia, Libero; Pusztai, Lajos; Saltzman, W Mark; Slack, Frank J

    2016-02-15

    Triple-negative breast cancer (TNBC) is an aggressive subtype with no clinically proven biologically targeted treatment options. The molecular heterogeneity of TNBC and lack of high frequency driver mutations other than TP53 have hindered the development of new and effective therapies that significantly improve patient outcomes. miRNAs, global regulators of survival and proliferation pathways important in tumor development and maintenance, are becoming promising therapeutic agents. We performed miRNA-profiling studies in different TNBC subtypes to identify miRNAs that significantly contribute to disease progression. We found that miR-34a was lost in TNBC, specifically within mesenchymal and mesenchymal stem cell-like subtypes, whereas expression of miR-34a targets was significantly enriched. Furthermore, restoration of miR-34a in cell lines representing these subtypes inhibited proliferation and invasion, activated senescence, and promoted sensitivity to dasatinib by targeting the proto-oncogene c-SRC. Notably, SRC depletion in TNBC cell lines phenocopied the effects of miR-34a reintroduction, whereas SRC overexpression rescued the antitumorigenic properties mediated by miR-34a. miR-34a levels also increased when cells were treated with c-SRC inhibitors, suggesting a negative feedback exists between miR-34a and c-SRC. Moreover, miR-34a administration significantly delayed tumor growth of subcutaneously and orthotopically implanted tumors in nude mice, and was accompanied by c-SRC downregulation. Finally, we found that miR-34a and SRC levels were inversely correlated in human tumor specimens. Together, our results demonstrate that miR-34a exerts potent antitumorigenic effects in vitro and in vivo and suggests that miR-34a replacement therapy, which is currently being tested in human clinical trials, represents a promising therapeutic strategy for TNBC. ©2015 American Association for Cancer Research.

  13. miR-34a Silences c-SRC to Attenuate Tumor Growth in Triple Negative Breast Cancer

    Science.gov (United States)

    Adams, Brian D.; Wali, Vikram B.; Cheng, Christopher J.; Inukai, Sachi; Booth, Carmen J.; Agarwal, Seema; Rimm, David L.; Győrffy, Balázs; Santarpia, Libero; Pusztai, Lajos; Saltzman, W. Mark; Slack, Frank J.

    2016-01-01

    Triple-negative breast cancer (TNBC) is an aggressive subtype with no clinically proven biologically targeted treatment options. The molecular heterogeneity of TNBC and lack of high frequency driver mutations other than TP53 have hindered the development of new and effective therapies that significantly improve patient outcomes. MicroRNAs (miRNAs), global regulators of survival and proliferation pathways important in tumor development and maintenance, are becoming promising therapeutic agents. We performed miRNA-profiling studies in different TNBC subtypes to identify miRNAs that significantly contribute to disease progression. We found that miR-34a was lost in TNBC, specifically within mesenchymal and mesenchymal-stem cell like subtypes, whereas expression of miR-34a targets were significantly enriched. Furthermore, restoration of miR-34a in cell lines representing these subtypes inhibited proliferation and invasion, activated senescence, and promoted sensitivity to dasatinib by targeting the proto-oncogene c-SRC. Notably, SRC-depletion in TNBC cell lines phenocopied the effects of miR-34a re-introduction, while SRC overexpression rescued the anti-tumorigenic properties mediated by miR-34a. miR-34a levels also increased when cells were treated with c-SRC inhibitors, suggesting a negative-feedback exists between miR-34a and c-SRC. Moreover, miR-34a administration significantly delayed tumor growth of subcutaneously and orthotopically implanted tumors in nude mice, and was accompanied by c-SRC downregulation. Finally, we found that miR-34a and SRC levels were inversely correlated in human tumor specimens. Together, our results demonstrate that miR-34a exerts potent anti-tumorigenic effects in vitro and in vivo, and suggests that miR-34a replacement therapy, which is currently being tested in human clinical trials, represents a promising therapeutic strategy for TNBC. PMID:26676753

  14. DNA methylation, genomic silencing, and links to nutrition and cancer.

    Science.gov (United States)

    McCabe, Dale C; Caudill, Marie A

    2005-06-01

    DNA methylation is a heritable epigenetic feature that is associated with transcriptional silencing, X-chromosome inactivation, genetic imprinting, and genomic stability. The addition of the methyl group is catalyzed by a family of DNA methyltransferases whose co-substrates are DNA and S-adenosylmethionine, the latter being derived from the methionine cycle. Aberrant DNA methylation is linked to numerous pathologies, including cancer. The purpose of this review is to describe DNA methylation and its functions, to examine the relationship between dietary methyl insufficiency and DNA methylation, and to evaluate the associations between DNA methylation and cancer.

  15. Silent God in a Wordy World. Silence in Ignatian Spirituality

    OpenAIRE

    García de Castro Valdés, S.J., José

    2016-01-01

    The Society of Jesus is an apostolic religious order involved in many different activities and missions. Jesuits live far away from monasteries and strict contemplative life. Nevertheless, one of the most well-known peculiarities of the Ignatian Spiritual Exercises is that a complete and absolute silence is required during the time of the retreat. Where and how should we place “silence” in the life of an Ignatian spiritual and mystical experience?

  16. Surface functionalisation of PLGA nanoparticles for gene silencing

    DEFF Research Database (Denmark)

    Andersen, Morten Østergaard; Lichawska, Agata; Arpanaei, Ayyoob

    2010-01-01

    . In addition, particles containing cetylated-PEI achieved 64% silencing of TNFα in J774.1 cells. This rapid method for surface modification of PLGA nanoparticles promotes its application for alternative cetylated functional derivatives as a strategy to control specific biological properties of nanoparticles.......This work presents a method for decorating the surface of poly (lactide-co-glycolide) (PLGA) nanoparticles with polyethyleneimine (PEI) utilising a cetyl derivative to improve surface functionalisation and siRNA delivery. Sub-micron particles were produced by an emulsion-diffusion method using...

  17. Nuclear architecture and gene silencing in olfactory sensory neurons.

    Science.gov (United States)

    Armelin-Correa, Lucia M; Nagai, Maíra H; Leme Silva, Artur G; Malnic, Bettina

    2014-01-01

    Odorants are discriminated by hundreds of odorant receptor (OR) genes, which are dispersed throughout the mammalian genome. The OR genes are expressed in a highly specialized type of cell, the olfactory sensory neuron. Each one of these neurons expresses one of the 2 alleles from one single OR gene type. The mechanisms underlying OR gene expression are unclear. Here we describe recent work demonstrating that the olfactory sensory neuron shows a particular nuclear architecture, and that the genomic OR loci are colocalized in silencing heterochromatin compartments within the nucleus. These discoveries highlight the important role played by epigenetic modifications and nuclear genome organization in the regulation of OR gene expression.

  18. Attenuation in Superconducting Circular Waveguides

    Directory of Open Access Journals (Sweden)

    K. H. Yeap

    2016-09-01

    Full Text Available We present an analysis on wave propagation in superconducting circular waveguides. In order to account for the presence of quasiparticles in the intragap states of a superconductor, we employ the characteristic equation derived from the extended Mattis-Bardeen theory to compute the values of the complex conductivity. To calculate the attenuation in a circular waveguide, the tangential fields at the boundary of the wall are first matched with the electrical properties (which includes the complex conductivity of the wall material. The matching of fields with the electrical properties results in a set of transcendental equations which is able to accurately describe the propagation constant of the fields. Our results show that although the attenuation in the superconducting waveguide above cutoff (but below the gap frequency is finite, it is considerably lower than that in a normal waveguide. Above the gap frequency, however, the attenuation in the superconducting waveguide increases sharply. The attenuation eventually surpasses that in a normal waveguide. As frequency increases above the gap frequency, Cooper pairs break into quasiparticles. Hence, we attribute the sharp rise in attenuation to the increase in random collision of the quasiparticles with the lattice structure.

  19. Sexuality and 'silence' among Khasi youth of Meghalaya, Northeast India.

    Science.gov (United States)

    War, Ryntihlin Jennifer; Albert, Sandra

    2013-01-01

    The importance of sex education has been well documented in the literature, but there exists a lack of research involving indigenous youth in India. This paper describes perceptions, knowledge and attitudes towards sex education, sexuality, pre-marital sex, rape and homosexuality among indigenous students from the matrilineal Khasi tribe attending a university in Meghalaya in northeast India. Qualitative and quantitative data were collected during and after reproductive health, sexuality and life skills courses. Despite the impression of sexual permissiveness of indigenous peoples that exists in India, students reported a societal silence on issues related to sexuality. Lack of appropriate words in the indigenous language potentially contributes to this silence. Although co-habitation is common and culturally acceptable, students disapproved of pre-marital sex. The influence of Christianisation was also perceived in the frequent reference to sin and guilt associated with masturbation, homosexuality, pre-marital sex and abortion. Students reported that the sex education received in school was 'childish' and inadequate for their adult needs. Many had unrealistic images of what constituted 'normal' sex and also blamed women for rape. The majority of indigenous students expressed the need for non-judgmental fora for discussions on sexual health and for sexuality education.

  20. 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.

  1. Epigenetic silencing of serine protease HTRA1 drives polyploidy

    International Nuclear Information System (INIS)

    Schmidt, Nina; Irle, Inga; Ripkens, Kamilla; Lux, Vanda; Nelles, Jasmin; Johannes, Christian; Parry, Lee; Greenow, Kirsty; Amir, Sarah; Campioni, Mara; Baldi, Alfonso; Oka, Chio; Kawaichi, Masashi; Clarke, Alan R.; Ehrmann, Michael

    2016-01-01

    Increased numbers and improperly positioned centrosomes, aneuploidy or polyploidy, and chromosomal instability are frequently observed characteristics of cancer cells. While some aspects of these events and the checkpoint mechanisms are well studied, not all players have yet been identified. As the role of proteases other than the proteasome in tumorigenesis is an insufficiently addressed question, we investigated the epigenetic control of the widely conserved protease HTRA1 and the phenotypes of deregulation. Mouse embryonal fibroblasts and HCT116 and SW480 cells were used to study the mechanism of epigenetic silencing of HTRA1. In addition, using cell biological and genetic methods, the phenotypes of downregulation of HTRA1 expression were investigated. HTRA1 is epigenetically silenced in HCT116 colon carcinoma cells via the epigenetic adaptor protein MBD2. On the cellular level, HTRA1 depletion causes multiple phenotypes including acceleration of cell growth, centrosome amplification and polyploidy in SW480 colon adenocarcinoma cells as well as in primary mouse embryonic fibroblasts (MEFs). Downregulation of HTRA1 causes a number of phenotypes that are hallmarks of cancer cells suggesting that the methylation state of the HtrA1 promoter may be used as a biomarker for tumour cells or cells at risk of transformation. The online version of this article (doi:10.1186/s12885-016-2425-8) contains supplementary material, which is available to authorized users

  2. Characterization and subcellular localization of an RNA silencing suppressor encoded by Rice stripe tenuivirus

    International Nuclear Information System (INIS)

    Xiong Ruyi; Wu Jianxiang; Zhou Yijun; Zhou Xueping

    2009-01-01

    Rice stripe virus (RSV) is a single-stranded (ss) RNA virus belonging to the genus Tenuivirus. RSV is present in many East Asian countries and causes severe diseases in rice fields, especially in China. In this study, we analyzed six proteins encoded by the virus for their abilities to suppress RNA silencing in plant using a green fluorescent protein (GFP)-based transient expression assay. Our results indicate that NS3 encoded by RSV RNA3, but not other five RSV encoded proteins, can strongly suppress local GFP silencing in agroinfiltrated Nicotiana benthamiana leaves. NS3 can reverse the GFP silencing, it can also prevent long distance spread of silencing signals which have been reported to be necessary for inducing systemic silencing in host plants. The NS3 protein can significantly reduce the levels of small interfering RNAs (siRNAs) in silencing cells, and was found to bind 21-nucleotide ss-siRNA, siRNA duplex and long ssRNA but not long double-stranded (ds)-RNA. Both N and C terminal of the NS3 protein are critical for silencing suppression, and mutation of the putative nuclear localization signal decreases its local silencing suppression efficiency and blocks its systemic silencing suppression. The NS3-GFP fusion protein and NS3 were shown to accumulate predominantly in nuclei of onion, tobacco and rice cells through transient expression assay or immunocytochemistry and electron microscopy. In addition, transgenic rice and tobacco plants expressing the NS3 did not show any apparent alteration in plant growth and morphology, although NS3 was proven to be a pathogenicity determinant in the PVX heterogenous system. Taken together, our results demonstrate that RSV NS3 is a suppressor of RNA silencing in planta, possibly through sequestering siRNA molecules generated in cells that are undergoing gene silencing.

  3. Josephson tunnel junction microwave attenuator

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Shchukin, A. V.

    1993-01-01

    A new element for superconducting electronic circuitry-a variable attenuator-has been proposed, designed, and successfully tested. The principle of operation is based on the change in the microwave impedance of a superconductor-insulator-superconductor (SIS) Josephson tunnel junction when dc biased...... at different points in the current-voltage characteristic. Both numerical calculations based on the Tien-Gordon theory and 70-GHz microwave experiments have confirmed the wide dynamic range (more than 15-dB attenuation for one stage) and the low insertion loss in the ''open'' state. The performance of a fully...... integrated submillimeter receiver circuit which comprises a flux-flow oscillator (FFO) as local oscillator, a superconducting variable attenuator, and a microwave SIS detector with tuned-out capacitance is also reported....

  4. The LCLS Gas Attenuator Revisited

    International Nuclear Information System (INIS)

    Ryutov, D

    2005-01-01

    In the report ''X-ray attenuation cell'' [1] a preliminary analysis of the gas attenuator for the Linac Coherent Light Source (LCLS) was presented. This analysis was carried out for extremely stringent set of specifications. In particular, a very large diameter for the unobstructed beam was set (1 cm) to accommodate the spontaneous radiation; the attenuator was supposed to cover the whole range of energies of the coherent radiation, from 800 eV to 8000 eV; the maximum attenuation was set at the level of 10 4 ; the use of solid attenuators was not allowed, as well as the use of rotating shutters. The need to reach a sufficient absorption at the high-energy end of the spectrum predetermined the choice of Xe as the working gas (in order to have a reasonable absorption at a not-too-high pressure). A sophisticated differential pumping system that included a Penning-type ion pump was suggested in order to minimize the gas leak into the undulator/accelerator part of the facility. A high cost of xenon meant also that an efficient (and expensive) gas-recovery system would have to be installed. The main parameter that determined the high cost and the complexity of the system was a large radius of the orifice. The present viewpoint allows for much smaller size of the orifice, r 0 = 1.5 mm. (1) The use of solid attenuators is also allowed (R.M. Bionta, private communication). It is, therefore, worthwhile to reconsider various parameters of the gas attenuator for these much less stringent conditions. This brief study should be considered as a physics input for the engineering design. As a working gas we consider now the argon, which, on the one hand, provides a reasonable absorption lengths and, on the other hand, is inexpensive enough to be exhausted into the atmosphere (no recovery). The absorption properties of argon are illustrated by Fig.1 where the attenuation factor A is shown for various beam energies, based on Ref. [2]. The other relevant parameters for argon are

  5. 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.

  6. Virus-induced gene silencing and Agrobacterium tumefaciens-mediated transient expression in Nicotiana tabacum

    NARCIS (Netherlands)

    Zhang, Z.; Thomma, B.P.H.J.

    2014-01-01

    Virus-induced gene silencing (VIGS) is a rapid method for transient silencing of plant genes. In this chapter, we describe the methodology for Tobacco rattle virus (TRV)-based VIGS in Nicotiana tabacum. In combination with subsequent co-expression of the tomato immune receptor Ve1 and the

  7. 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...

  8. Self-Silencing, Emotional Awareness, and Eating Behaviors in College Women

    Science.gov (United States)

    Shouse, Sarah H.; Nilsson, Johanna

    2011-01-01

    Self-silencing (or the suppression of expressing one's thoughts, feelings, and needs) can have a negative impact on the mental health of women, from depression to disordered eating behaviors. The authors examined the relationship between self-silencing and disordered eating as well as intuitive eating. The authors also explored whether emotional…

  9. Identification and characterization of two RNA silencing suppressors encoded by ophioviruses

    NARCIS (Netherlands)

    Robles Luna, Gabriel; Reyes, Carina A.; Peña, Eduardo J.; Ocolotobiche, Eliana; Baeza, Cecilia; Borniego, Maria Belén; Kormelink, Richard; García, María Laura

    2017-01-01

    Citrus psorosis virus and Mirafiori lettuce big-vein virus are two members of the genus Ophiovirus, family Ophioviridae. So far, how these viruses can interfere in the antiviral RNA silencing pathway is not known. In this study, using a local GFP silencing assay on Nicotiana benthamiana, the

  10. Distinct Effects of p19 RNA Silencing Suppressor on Small RNA Mediated Pathways in Plants.

    Directory of Open Access Journals (Sweden)

    Levente Kontra

    2016-10-01

    Full Text Available RNA silencing is one of the main defense mechanisms employed by plants to fight viruses. In change, viruses have evolved silencing suppressor proteins to neutralize antiviral silencing. Since the endogenous and antiviral functions of RNA silencing pathway rely on common components, it was suggested that viral suppressors interfere with endogenous silencing pathway contributing to viral symptom development. In this work, we aimed to understand the effects of the tombusviral p19 suppressor on endogenous and antiviral silencing during genuine virus infection. We showed that ectopically expressed p19 sequesters endogenous small RNAs (sRNAs in the absence, but not in the presence of virus infection. Our presented data question the generalized model in which the sequestration of endogenous sRNAs by the viral suppressor contributes to the viral symptom development. We further showed that p19 preferentially binds the perfectly paired ds-viral small interfering RNAs (vsiRNAs but does not select based on their sequence or the type of the 5' nucleotide. Finally, co-immunoprecipitation of sRNAs with AGO1 or AGO2 from virus-infected plants revealed that p19 specifically impairs vsiRNA loading into AGO1 but not AGO2. Our findings, coupled with the fact that p19-expressing wild type Cymbidium ringspot virus (CymRSV overcomes the Nicotiana benthamiana silencing based defense killing the host, suggest that AGO1 is the main effector of antiviral silencing in this host-virus combination.

  11. 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.

  12. Performing Silence: Gender, Violence, and Resistance in Women's Narratives from Lahaul, India

    Science.gov (United States)

    Bhattacharya, Himika

    2009-01-01

    This article presents two different ways of understanding silence, through a discussion of women's narratives of violence from Lahaul, India. Here I illustrate how feminist ethnography works its way into re-conceptualizing silence as a tool women use to resist existing patriarchal discourses of honor, tribe and nation. (Contains 1 note.)

  13. Giving Voice: Narrating silence, history and memory in André Brink ...

    African Journals Online (AJOL)

    This essay examines André Brink's two most recent novels, The Other Side of Silence (2002) and Before I Forget (2004), in terms of their voicing of silence and the rewriting of history and memory. Each has a theme familiar to Brink's readers – an historical story of colonial violence and violation avenged; and the recounting ...

  14. Analysing the significance of silence in qualitative interviewing: questioning and shifting power relations

    DEFF Research Database (Denmark)

    Bengtsson, Tea Torbenfeldt; Fynbo, Lars

    2017-01-01

    In this article we analyse the significance of silence in qualitative interviews with 36 individuals interviewed about high-risk, illegal activities. We describe how silence expresses a dynamic power relationship between interviewer and interviewee. In the analysis, we focus on two different type...

  15. Down-Regulation of Gene Expression by RNA-Induced Gene Silencing

    Science.gov (United States)

    Travella, Silvia; Keller, Beat

    Down-regulation of endogenous genes via post-transcriptional gene silencing (PTGS) is a key to the characterization of gene function in plants. Many RNA-based silencing mechanisms such as post-transcriptional gene silencing, co-suppression, quelling, and RNA interference (RNAi) have been discovered among species of different kingdoms (plants, fungi, and animals). One of the most interesting discoveries was RNAi, a sequence-specific gene-silencing mechanism initiated by the introduction of double-stranded RNA (dsRNA), homologous in sequence to the silenced gene, which triggers degradation of mRNA. Infection of plants with modified viruses can also induce RNA silencing and is referred to as virus-induced gene silencing (VIGS). In contrast to insertional mutagenesis, these emerging new reverse genetic approaches represent a powerful tool for exploring gene function and for manipulating gene expression experimentally in cereal species such as barley and wheat. We examined how RNAi and VIGS have been used to assess gene function in barley and wheat, including molecular mechanisms involved in the process and available methodological elements, such as vectors, inoculation procedures, and analysis of silenced phenotypes.

  16. Gain attenuation of gated framing camera

    International Nuclear Information System (INIS)

    Xiao Shali; Liu Shenye; Cao Zhurong; Li Hang; Zhang Haiying; Yuan Zheng; Wang Liwei

    2009-01-01

    The theoretic model of framing camera's gain attenuation is analyzed. The exponential attenuation curve of the gain along the pulse propagation time is simulated. An experiment to measure the coefficient of gain attenuation based on the gain attenuation theory is designed. Experiment result shows that the gain follows an exponential attenuation rule with a quotient of 0.0249 nm -1 , the attenuation coefficient of the pulse is 0.00356 mm -1 . The loss of the pulse propagation along the MCP stripline is the leading reason of gain attenuation. But in the figure of a single stripline, the gain dose not follow the rule of exponential attenuation completely, instead, there is a gain increase at the stripline bottom. That is caused by the reflection of the pulse. The reflectance is about 24.2%. Combining the experiment and theory, which design of the stripline MCP can improved the gain attenuation. (authors)

  17. Restoration of camptothecine production in attenuated endophytic fungus on re-inoculation into host plant and treatment with DNA methyltransferase inhibitor.

    Science.gov (United States)

    Vasanthakumari, M M; Jadhav, S S; Sachin, Naik; Vinod, G; Shweta, Singh; Manjunatha, B L; Kumara, P Mohana; Ravikanth, G; Nataraja, Karaba N; Uma Shaanker, R

    2015-10-01

    Fungal endophytes inhabit living tissues of plants without any apparent symptoms and in many cases are known to produce secondary metabolites similar to those produced by their respective host plants. However on sub-culture, the endophytic fungi gradually attenuate their ability to produce the metabolites. Attenuation has been a major constraint in realizing the potential of endophytic fungi as an alternative source of plant secondary metabolites. In this study, we report attempts to restore camptothecine (CPT) production in attenuated endophytic fungi isolated from CPT producing plants, Nothapodytes nimmoniana and Miquelia dentata when they are passed through their host plant or plants that produce CPT and when treated with a DNA methyl transferase inhibitor. Attenuated endophytic fungi that traversed through their host tissue or plants capable of synthesizing CPT, produced significantly higher CPT compared to the attenuated fungi. Attenuated fungus cultured in the presence of 5-azacytidine, a DNA methyltransferase inhibitor, had an enhanced CPT content compared to untreated attenuated fungus. These results indicate that the attenuation of CPT production in endophytic fungi could in principle be reversed by eliciting some signals from plant tissue, most likely that which prevents the methylation or silencing of the genes responsible for CPT biosynthesis.

  18. Ultrasonic attenuation in cuprate superconductors

    Indian Academy of Sciences (India)

    Ultrasonic attenuation in cuprate superconductors. T GUPTA1,∗ and D M GAITONDE1,2. 1Harish-Chandra Research Institute, Allahabad 211 019, India. 2High Pressure Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India. ∗. Email: gupta@mri.ernet.in. Abstract. We calculate the longitudinal ...

  19. A Generalized Correction for Attenuation.

    Science.gov (United States)

    Petersen, Anne C.; Bock, R. Darrell

    Use of the usual bivariate correction for attenuation with more than two variables presents two statistical problems. This pairwise method may produce a covariance matrix which is not at least positive semi-definite, and the bivariate procedure does not consider the possible influences of correlated errors among the variables. The method described…

  20. Attenuation of Vrancea events revisited

    International Nuclear Information System (INIS)

    Radulian, M.; Popa, M.; Grecu, B.; Panza, G.F.

    2003-11-01

    New aspects of the frequency-dependent attenuation of the seismic waves traveling from Vrancea subcrustal sources toward NW (Transylvanian Basin) and SE (Romanian Plain) are evidenced by the recent experimental data made available by the CALIXTO'99 tomography experiment. The observations validate the previous theoretical computations performed for the assessment, by means of a deterministic approach, of the seismic hazard in Romania. They reveal an essential aspect of the seismic ground motion attenuation, that has important implications on the probabilistic assessment of seismic hazard from Vrancea intermediate-depth earthquakes. The attenuation toward NW is shown to be a much stronger frequency-dependent effect than the attenuation toward SE and the seismic hazard computed by the deterministic approach fits satisfactorily well the observed ground motion distribution in the low-frequency band (< 1 Hz). The apparent contradiction with the historically-based intensity maps arises mainly from a systematic difference in the vulnerability (buildings eigenperiod) of the buildings in the intra- and extra-Carpathians regions. (author)

  1. Compact plasmonic variable optical attenuator

    DEFF Research Database (Denmark)

    Leosson, Kristjan; Rosenzveig, Tiberiu; Hermannsson, Pétur Gordon

    2008-01-01

    We demonstrate plasmonic nanowire-based thermo-optic variable optical attenuators operating in the 1525-1625 nm wavelength range. The devices have a footprint as low as 1 mm, extinction ratio exceeding 40 dB, driving voltage below 3 V, and full modulation bandwidth of 1 kHz. The polarization...

  2. Postpartum Depression: How Childbirth Educators Can Help Break the Silence

    Science.gov (United States)

    Zauderer, Cheryl

    2009-01-01

    The voices of women suffering from postpartum depression are often silent. Women are reluctant to reveal to others that they are unhappy after the birth of their babies. Much has been written on possible causes, risk factors, and treatments for postpartum depression, but little has been done to investigate why women take so long to seek help. Early detection and treatment are key to a full recovery. Childbirth educators are in the position to offer anticipatory guidance on possible complications of the postpartum period, including postpartum depression. This article explores why women with postpartum depression choose to suffer in silence and suggests how childbirth educators can help new mothers find their voices. PMID:20190853

  3. A Resonant Silence: For an Ethnographic History of Abortion

    Directory of Open Access Journals (Sweden)

    Flávia de Mattos Motta

    2008-05-01

    Full Text Available By using methods of the fields of History and Anthropology, this study investigated the practice of abortion in southern Brazil in the first half of the twentieth century. The examination of primary sources and interviews with elderly women intended to unveil a huge silence around this practice, which leaves very few historical sources to be investigated, and hides those memories. This text presents data collected by this survey and analyzes the diversity of representations over abortion and the ambiguities that this theme causes on the subjects involved. The practice of abortion must be understood as inserted into a context of power. The subjects operate from multiple sources of knowledge and within a morality network composed of contradictory elements.

  4. Hearing the Silence: Children’s Voices on Violence

    Directory of Open Access Journals (Sweden)

    Kathryn S. Collins

    2003-05-01

    Full Text Available Each year more than five million children in the United States are exposed to traumatizing events in their communities. This paper presents a discussion of multiple areas in violence and victimization research that needs to be continued as well as provides suggestions on how to un-silence child survivors through bridging the gaps between research and practice. It reviews the overarching problem of violence in the U.S. at the domestic and global levels and the effects of victimization. Suggestions on how to study possible mediators and moderators of victimization and individual and family adjustment, including: 1 The ecological perspective; 2 Court process and verdict; and 3Utilization of victim services, are explored. Finally, a rationale and examples of combining qualitative and quantitative methods in future research that uses children’s attributions of violence as a mediator are presented.

  5. Sonic memory interventions against politics of urban silencing

    Directory of Open Access Journals (Sweden)

    Hofman Ana

    2017-01-01

    Full Text Available We discuss the political implications of the noise/silence dialectic in order to reflect on the urban and social materialities of sonic memory activism in the post- Yugoslav space. We see the privatization of public space as one of the defining issues of current socio-political tensions and we strive to offer a more nuanced model for thinking about grassroots practices of musicking and listening in the context of resistance and power and control redistribution. Discussing sonic interventions in Ljubljana and Belgrade enables us both to uncover how important global processes are reflected in these local contexts and to locate diversity of present practices of resistance. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 177004: Serbian Musical Identities Within Local and Global Frameworks: Traditions, Changes, Challenges

  6. Prognostic significance of aberrantly silenced ANPEP expression in prostate cancer

    DEFF Research Database (Denmark)

    Sørensen, Karina Dalsgaard; Abildgaard, Mette Opstrup; Haldrup, Christa

    2013-01-01

    Background:Novel biomarkers for prostate cancer (PC) are urgently needed. This study investigates the expression, epigenetic regulation, and prognostic potential of ANPEP in PC.Methods:Aminopeptidase N (APN; encoded by ANPEP) expression was analysed by immunohistochemistry using tissue microarrays...... in three hypermethylated prostate cell lines, suggesting epigenetic silencing. Negative APN immunoreactivity was significantly associated with short RFS and short CSS in the RP and CT cohort, respectively, independently of routine clinicopathological predictors. Combining APN with a known angiogenesis...... marker (vascular endothelial growth factor or microvessel density) improved risk prediction significantly in both cohorts.Conclusion:Our results suggest negative APN immunoreactivity as a new independent adverse prognostic factor for patients with clinically localised PC and, furthermore, that epigenetic...

  7. Silencing of voices in a Swedish science classroom

    Science.gov (United States)

    Ramos de Robles, S. Lizette

    2018-03-01

    From a sociocultural perspective, I discuss data from a Swedish science classroom presented in María Gómez's article "Student Explanations of their Science Teachers' Assessments, Grading Practices, and How they learn Science". In this discussion, I focus on the need to change existing conceptions of assessment in the teaching and learning of science. Next, I talk about the importance of taking into consideration the dialectic between agency and passivity as filters in order to understand what student silence may signify in science classes as well as in relation to their perceptions of assessment. I conclude with the importance of the teacher's role in developing formative assessment, along with the challenges in developing assessments which transform science education into a relevant field of knowledge for both students and society at large.

  8. Flexible tools for gene expression and silencing in tomato.

    Science.gov (United States)

    Fernandez, Ana I; Viron, Nicolas; Alhagdow, Moftah; Karimi, Mansour; Jones, Matthew; Amsellem, Ziva; Sicard, Adrien; Czerednik, Anna; Angenent, Gerco; Grierson, Donald; May, Sean; Seymour, Graham; Eshed, Yuval; Lemaire-Chamley, Martine; Rothan, Christophe; Hilson, Pierre

    2009-12-01

    As a genetic platform, tomato (Solanum lycopersicum) benefits from rich germplasm collections and ease of cultivation and transformation that enable the analysis of biological processes impossible to investigate in other model species. To facilitate the assembly of an open genetic toolbox designed to study Solanaceae, we initiated a joint collection of publicly available gene manipulation tools. We focused on the characterization of promoters expressed at defined time windows during fruit development, for the regulated expression or silencing of genes of interest. Five promoter sequences were captured as entry clones compatible with the versatile MultiSite Gateway format: PPC2, PG, TPRP, and IMA from tomato and CRC from Arabidopsis (Arabidopsis thaliana). Corresponding transcriptional fusions were made with the GUS gene, a nuclear-localized GUS-GFP reporter, and the chimeric LhG4 transcription factor. The activity of the promoters during fruit development and in fruit tissues was confirmed in transgenic tomato lines. Novel Gateway destination vectors were generated for the transcription of artificial microRNA (amiRNA) precursors and hairpin RNAs under the control of these promoters, with schemes only involving Gateway BP and LR Clonase reactions. Efficient silencing of the endogenous phytoene desaturase gene was demonstrated in transgenic tomato lines producing a matching amiRNA under the cauliflower mosaic virus 35S or PPC2 promoter. Lastly, taking advantage of the pOP/LhG4 two-component system, we found that well-characterized flower-specific Arabidopsis promoters drive the expression of reporters in patterns generally compatible with heterologous expression. Tomato lines and plasmids will be distributed through a new Nottingham Arabidopsis Stock Centre service unit dedicated to Solanaceae resources.

  9. Polyphenoloxidase Silencing Affects Latex Coagulation in Taraxacum Species1[W

    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

    2009-01-01

    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. PMID:19605551

  10. Dismantling the Silence: LGBTQ Aging Emerging From the Margins.

    Science.gov (United States)

    Fredriksen-Goldsen, Karen I

    2017-02-01

    Historical, environmental, and cultural contexts intersect with aging, sexuality, and gender across communities and generations. My scholarship investigates health and well-being over the life course across marginalized communities, including LGBTQ (lesbian, gay, bisexual, transgender, and queer) midlife and older adults, native communities experiencing cardiovascular risk, and families in China living with HIV, in order to balance the realities of unique lives in contemporary society. By probing the intersection of age, sexuality, and gender, my analysis is informed by both personal and professional experiences. With the death of my partner occurring at a time of profound invisibility and silence before HIV/AIDS, I found my life out of sync, experiencing a loss without a name. My life was thrust into a paradox: My relationship was defined by a world that refused to recognize it. This essay provides an opportunity for me to weave together how such critical turning points in my own life helped shape my approach to gerontology and how gerontology has informed my work and life. Reflecting on this journey, I illustrate the ways in which historical, structural, environmental, psychosocial, and biological factors affect equity, and the health-promoting and adverse pathways to health and well-being across marginalized communities. Although gerontology as a discipline has historically silenced the lives of marginalized older adults, it has much to learn from these communities. The growing and increasingly diverse older adult population provides us with unique opportunities to better understand both cultural variations and shared experiences in aging over the life course. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Silencing Intersectin 1 Slows Orthotopic Neuroblastoma Growth in Mice.

    Science.gov (United States)

    Harris, Jamie; Herrero-Garcia, Erika; Russo, Angela; Kajdacsy-Balla, Andre; O'Bryan, John P; Chiu, Bill

    2017-11-01

    Neuroblastoma accounts for 15% of all pediatric cancer deaths. Intersectin 1 (ITSN1), a scaffold protein involved in phosphoinositide 3-kinase (PI3K) signaling, regulates neuroblastoma cells independent of MYCN status. We hypothesize that by silencing ITSN1 in neuroblastoma cells, tumor growth will be decreased in an orthotopic mouse tumor model. SK-N-AS neuroblastoma cells transfected with empty vector (pSR), vectors expressing scrambled shRNA (pSCR), or shRNAs targeting ITSN1 (sh#1 and sh#2) were used to create orthotopic neuroblastoma tumors in mice. Volume was monitored weekly with ultrasound. End-point was tumor volume >1000 mm. Tumor cell lysates were analyzed with anti-ITSN1 antibody by Western blot. Orthotopic tumors were created in all cell lines. Twenty-five days post injection, pSR tumor size was 917.6±247.7 mm, pSCR was 1180±159.9 mm, sh#1 was 526.3±212.8 mm, and sh#2 was 589.2±74.91 mm. sh#1-tumors and sh#2-tumors were smaller than pSCR (P=0.02), no difference between sh#1 and sh#2. Survival was superior in sh#2-tumors (P=0.02), trended towards improved survival in sh#1-tumors (P=0.09), compared with pSCR-tumors, no difference in pSR tumors. Western blot showed decreased ITSN1 expression in sh#1 and sh#2 compared with pSR and pSCR. Silencing ITSN1 in neuroblastoma cells led to decreased tumor growth in an orthotopic mouse model. Orthotopic animal models can provide insight into the role of ITSN1 pathways in neuroblastoma tumorigenesis.

  12. AMFR gene silencing inhibits the differentiation of porcine preadipocytes.

    Science.gov (United States)

    Chen, C Z; Zhu, Y N; Chai, M L; Dai, L S; Gao, Y; Jiang, H; Zhang, L J; Ding, Y; Liu, S Y; Li, Q Y; Lu, W F; Zhang, J B

    2016-04-07

    Our study clarifies the role of the autocrine motility factor receptor (AMFR) gene in porcine preadipocyte differentiation. AMFR-siRNA was transfected into porcine preadipocytes and the preadipocytes were induced to differentiation. Subsequently, qRT-PCR was conducted to examine changes in mRNA expression of a series of genes in porcine preadipocytes, including AMFR, sterol-regulatory element-binding protein-1a (SREBP1a), SREBP2, insulin-induced gene 1 (Insig1), and Insig2. Expression changes in the mRNA of genes regulating adipocyte differentiation were also analyzed using qRT-PCR, including peroxisome proliferator-activated receptor gamma (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBPα), and Kruppel-like factor 2 (KLF2). Western blot analysis was conducted to examine the changes in AMFR protein expression in porcine preadipocytes. Additionally, morphological changes in differentiated porcine preadipocytes were examined by oil red O staining, and changes in optical density (OD) values were measured using an ultraviolet spectrophotometer. At 24 h after transfection with AMFR-siRNA, AMFR mRNA expression significantly reduced (P SREBP1a, SREBP2, Insig1, and C/EBPα was significantly reduced (P < 0.01), whereas the expression of KLF2 mRNA was significantly elevated (P < 0.01). After induction of preadipocyte differentiation, the number of lipid droplets decreased in the AMFR-silenced group, and the OD value markedly reduced (P < 0.05). In addition, the expression of C/EBPα mRNA significantly decreased (P < 0.05), whereas the expression of KLF2 mRNA considerably increased (P < 0.05). Taken together, silencing of the AMFR gene inhibits the differentiation of porcine preadipocytes.

  13. Hypoxia Silences Retrotrapezoid Nucleus Respiratory Chemoreceptors via Alkalosis

    Science.gov (United States)

    Basting, Tyler M.; Burke, Peter G.R.; Kanbar, Roy; Viar, Kenneth E.; Stornetta, Daniel S.; Stornetta, Ruth L.

    2015-01-01

    In conscious mammals, hypoxia or hypercapnia stimulates breathing while theoretically exerting opposite effects on central respiratory chemoreceptors (CRCs). We tested this theory by examining how hypoxia and hypercapnia change the activity of the retrotrapezoid nucleus (RTN), a putative CRC and chemoreflex integrator. Archaerhodopsin-(Arch)-transduced RTN neurons were reversibly silenced by light in anesthetized rats. We bilaterally transduced RTN and nearby C1 neurons with Arch (PRSx8-ArchT-EYFP-LVV) and measured the cardiorespiratory consequences of Arch activation (10 s) in conscious rats during normoxia, hypoxia, or hyperoxia. RTN photoinhibition reduced breathing equally during non-REM sleep and quiet wake. Compared with normoxia, the breathing frequency reduction (ΔfR) was larger in hyperoxia (65% FiO2), smaller in 15% FiO2, and absent in 12% FiO2. Tidal volume changes (ΔVT) followed the same trend. The effect of hypoxia on ΔfR was not arousal-dependent but was reversed by reacidifying the blood (acetazolamide; 3% FiCO2). ΔfR was highly correlated with arterial pH up to arterial pH (pHa) 7.5 with no frequency inhibition occurring above pHa 7.53. Blood pressure was minimally reduced suggesting that C1 neurons were very modestly inhibited. In conclusion, RTN neurons regulate eupneic breathing about equally during both sleep and wake. RTN neurons are the first putative CRCs demonstrably silenced by hypocapnic hypoxia in conscious mammals. RTN neurons are silent above pHa 7.5 and increasingly active below this value. During hyperoxia, RTN activation maintains breathing despite the inactivity of the carotid bodies. Finally, during hypocapnic hypoxia, carotid body stimulation increases breathing frequency via pathways that bypass RTN. PMID:25589748

  14. Dismantling the Silence: LGBTQ Aging Emerging From the Margins

    Science.gov (United States)

    Fredriksen-Goldsen, Karen I.

    2017-01-01

    Historical, environmental, and cultural contexts intersect with aging, sexuality, and gender across communities and generations. My scholarship investigates health and well-being over the life course across marginalized communities, including LGBTQ (lesbian, gay, bisexual, transgender, and queer) midlife and older adults, native communities experiencing cardiovascular risk, and families in China living with HIV, in order to balance the realities of unique lives in contemporary society. By probing the intersection of age, sexuality, and gender, my analysis is informed by both personal and professional experiences. With the death of my partner occurring at a time of profound invisibility and silence before HIV/AIDS, I found my life out of sync, experiencing a loss without a name. My life was thrust into a paradox: My relationship was defined by a world that refused to recognize it. This essay provides an opportunity for me to weave together how such critical turning points in my own life helped shape my approach to gerontology and how gerontology has informed my work and life. Reflecting on this journey, I illustrate the ways in which historical, structural, environmental, psychosocial, and biological factors affect equity, and the health-promoting and adverse pathways to health and well-being across marginalized communities. Although gerontology as a discipline has historically silenced the lives of marginalized older adults, it has much to learn from these communities. The growing and increasingly diverse older adult population provides us with unique opportunities to better understand both cultural variations and shared experiences in aging over the life course. PMID:28053011

  15. Position-Dependent Methylation and Transcriptional Silencing of Transgenes in Inverted T-DNA Repeats: Implications for Posttranscriptional Silencing of Homologous Host Genes in Plants

    Science.gov (United States)

    Stam, Maike; Viterbo, Ada; Mol, Joseph N. M.; Kooter, Jan M.

    1998-01-01

    Posttranscriptional silencing of chalcone synthase (Chs) genes in petunia transformants occurs by introducing T-DNAs that contain a promoter-driven or promoterless Chs transgene. With the constructs we used, silencing occurs only by T-DNA loci which are composed of two or more T-DNA copies that are arranged as inverted repeats (IRs). Since we are interested in the mechanism by which these IR loci induce silencing, we have analyzed different IR loci and nonsilencing single-copy (S) T-DNA loci with respect to the expression and methylation of the transgenes residing in these loci. We show that in an IR locus, the transgenes located proximal to the IR center are much more highly methylated than are the distal genes. A strong silencing locus composed of three inverted T-DNAs bearing promoterless Chs transgenes was methylated across the entire locus. The host Chs genes in untransformed plants were moderately methylated, and no change in methylation was detected when the genes were silenced. Run-on transcription assays showed that promoter-driven transgenes located proximal to the center of a particular IR are transcriptionally more repressed than are the distal genes of the same IR locus. Transcription of the promoterless Chs transgenes could not be detected. In the primary transformant, some of the IR loci were detected together with an unlinked S locus. We observed that the methylation and expression characteristics of the transgenes of these S loci were comparable to those of the partner IR loci, suggesting that there has been cross talk between the two types of loci. Despite the similar features, S loci are unable to induce silencing, indicating that the palindromic arrangement of the Chs transgenes in the IR loci is critical for silencing. Since transcriptionally silenced transgenes in IRs can trigger posttranscriptional silencing of the host genes, our data are most consistent with a model of silencing in which the transgenes physically interact with the

  16. 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

  17. Ways to Promote the Classroom Participation of International Students by Understanding the Silence of Japanese University Students

    Science.gov (United States)

    Kim, Soonhyang; Ates, Burcu; Grigsby, Yurimi; Kraker, Stefani; Micek, Timothy A.

    2016-01-01

    The authors explored the role of silence and deciphered its meaning and usefulness as a teaching and learning strategy for Japanese students through a survey of Japanese university students in their home country. This study has revealed that participant responses were evenly divided among comfortable with silence, uncomfortable with silence, and…

  18. Mesenchymal stem cell-derived extracellular vesicles attenuate kidney inflammation.

    Science.gov (United States)

    Eirin, Alfonso; Zhu, Xiang-Yang; Puranik, Amrutesh S; Tang, Hui; McGurren, Kelly A; van Wijnen, Andre J; Lerman, Amir; Lerman, Lilach O

    2017-07-01

    Mesenchymal stem/stromal cells (MSCs) have distinct capability for renal repair, but may have safety concerns. MSC-derived extracellular vesicles emerged as a novel noncellular alternative. Using a porcine model of metabolic syndrome and renal artery stenosis we tested whether extracellular vesicles attenuate renal inflammation, and if this capacity is mediated by their cargo of the anti-inflammatory cytokine interleukin (IL) 10. Pigs with metabolic syndrome were studied after 16 weeks of renal artery stenosis untreated or treated four weeks earlier with a single intrarenal delivery of extracellular vesicles harvested from adipose tissue-derived autologous MSCs. Lean and sham metabolic syndrome animals served as controls (seven each). Five additional pigs with metabolic syndrome and renal artery stenosis received extracellular vesicles with pre-silenced IL10 (IL10 knock-down). Single-kidney renal blood flow, glomerular filtration rate, and oxygenation were studied in vivo and renal injury pathways ex vivo. Retention of extracellular vesicles in the stenotic kidney peaked two days after delivery and decreased thereafter. Four weeks after injection, extracellular vesicle fragments colocalized with stenotic-kidney tubular cells and macrophages, indicating internalization or fusion. Extracellular vesicle delivery attenuated renal inflammation, and improved medullary oxygenation and fibrosis. Renal blood flow and glomerular filtration rate fell in metabolic syndrome and renal artery stenosis compared to metabolic syndrome, but was restored in pigs treated with extracellular vesicles. These renoprotective effects were blunted in pigs treated with IL10-depleted extracellular vesicles. Thus, extracellular vesicle-based regenerative strategies might be useful for patients with metabolic syndrome and renal artery stenosis. Copyright © 2017 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

  19. Adaptation of the Four Forms of Employee Silence Scale in a Polish sample

    Directory of Open Access Journals (Sweden)

    Krystyna Adamska

    2017-06-01

    Full Text Available Background Silence is understood as a decision not to speak up in situations of observed irregularities both in productivity and ethics. The study examined the validity of the Four Forms of Employee Silence Scale (FFESS in the Polish population. The scale is a four-factor measure designed to capture differently motivated tendencies to be silent in organizations. The scale distinguishes acquiescent, quiescent, prosocial and opportunistic silence. Employee silence has been linked to many important individual outcomes: failure to react to ethical transgressions, stress and depression, and lower creativity and productivity. Participants and procedure A total of 1044 employees of various organizations working for at least six months at a given position provided the responses for the validation study. Results The results confirmed the superiority of the four-factor model shown by adequate fit indexes: The FFESS has adequate internal consistency at both the scale and item levels. The criterion-related validity of the scale was established by correlating four forms of silence with measures of emotional attitude toward organization, procedural justice, relational contract and turnover intention. Conclusions The four forms of employee silence are empirically distinct concepts in the Polish sample. The scale may be used as the measurement of individual differences. It can also serve as a tool for diagnosing a climate of silence in an organization.

  20. RNA Silencing in Plants: Mechanisms, Technologies and Applications in Horticultural Crops.

    Science.gov (United States)

    Guo, Qigao; Liu, Qing; Smith, Neil A; Liang, Guolu; Wang, Ming-Bo

    2016-12-01

    Understanding the fundamental nature of a molecular process or a biological pathway is often a catalyst for the development of new technologies in biology. Indeed, studies from late 1990s to early 2000s have uncovered multiple overlapping but functionally distinct RNA silencing pathways in plants, including the posttranscriptional microRNA and small interfering RNA pathways and the transcriptional RNA-directed DNA methylation pathway. These findings have in turn been exploited for developing artificial RNA silencing technologies such as hairpin RNA, artificial microRNA, intrinsic direct repeat, 3' UTR inverted repeat, artificial trans-acting siRNA, and virus-induced gene silencing technologies. Some of these RNA silencing technologies, such as the hairpin RNA technology, have already been widely used for genetic improvement of crop plants in agriculture. For horticultural plants, RNA silencing technologies have been used to increase disease and pest resistance, alter plant architecture and flowering time, improve commercial traits of fruits and flowers, enhance nutritional values, remove toxic compounds and allergens, and develop high-value industrial products. In this article we aim to provide an overview of the RNA silencing pathways in plants, summarize the existing RNA silencing technologies, and review the current progress in applying these technologies for the improvement of agricultural crops particularly horticultural crops.

  1. A translational silencing function of MCPIP1/Regnase-1 specified by the target site context.

    Science.gov (United States)

    Behrens, Gesine; Winzen, Reinhard; Rehage, Nina; Dörrie, Anneke; Barsch, Monika; Hoffmann, Anne; Hackermüller, Jörg; Tiedje, Christopher; Heissmeyer, Vigo; Holtmann, Helmut

    2018-02-19

    The expression of proteins during inflammatory and immune reactions is coordinated by post-transcriptional mechanisms. A particularly strong suppression of protein expression is exerted by a conserved translational silencing element (TSE) identified in the 3' UTR of NFKBIZ mRNA, which is among the targets of the RNA-binding proteins Roquin-1/2 and MCPIP1/Regnase-1. We present evidence that in the context of the TSE MCPIP1, so far known for its endonuclease activity toward mRNAs specified by distinct stem-loop (SL) structures, also suppresses translation. Overexpression of MCPIP1 silenced translation in a TSE-dependent manner and reduced ribosome occupancy of the mRNA. Correspondingly, MCPIP1 depletion alleviated silencing and increased polysomal association of the mRNA. Translationally silenced NFKBIZ or reporter mRNAs were mostly capped, polyadenylated and ribosome associated. Furthermore, MCPIP1 silenced also cap-independent, CrPV-IRES-dependent translation. This suggests that MCPIP1 suppresses a post-initiation step. The TSE is predicted to form five SL structures. SL4 and 5 resemble target structures reported for MCPIP1 and together were sufficient for MCPIP1 binding and mRNA destabilization. Translational silencing, however, required SL1-3 in addition. Thus the NFKBIZ TSE functions as an RNA element in which sequences adjacent to the site of interaction with MCPIP1 and dispensable for accelerated mRNA degradation extend the functional repertoire of MCPIP1 to translational silencing.

  2. Generosity or genocide? Identity implications of silence in American Thanksgiving commemorations.

    Science.gov (United States)

    Kurtiş, Tuğçe; Adams, Glenn; Bird, Michael Yellow

    2010-02-01

    This paper investigates the identity implications of silence about genocide in commemorations of American Thanksgiving. In Study 1 we assessed the co-occurrence of national glorification themes with different forms of silence in commemoration products by conducting a content analysis of presidential Thanksgiving proclamations. In Study 2 we examined the extent to which different commemoration products are infused with particular beliefs and desires by measuring participants' reactions to different Thanksgiving commemorations-a literal-silence condition that did not mention Indigenous Peoples, an interpretive-silence condition that mentioned Indigenous Peoples but did not explicitly mention genocidal conquest, and an anti-silence condition that did mention genocidal conquest-as a function of national glorification. In Study 3 we manipulated exposure to different Thanksgiving commemorations (with associated forms of silence) and assessed the impact on national glorification and identity-relevant action. Results provide evidence for the hypothesised, bi-directional relationship between national glorification and silence about genocide in commemorations of American Thanksgiving.

  3. Language matters: towards an understanding of silence and humour in medical education.

    Science.gov (United States)

    Lingard, Lorelei

    2013-01-01

    This paper considers the state of the science regarding language matters in medical education, with particular attention to two informal language practices: silence and humour. Silence and humour pervade clinical training settings, although we rarely attend explicitly to them. This paper considers the treatment of these topics in our field to date and introduces a selection of the scholarship on silence and humour from other fields, including philosophy, sociology, anthropology, linguistics and rhetoric. Particular attention is paid to distilling the theoretical and methodological possibilities for an elaborated research agenda around silence and humour in medical education. These two language practices assume a variety of forms and serve a range of social functions. Episodes of silence and humour are intimately tied to their relational and institutional contexts. Power often figures centrally, although not predictably. A rich theoretical and methodological basis exists on which to elaborate a research agenda around silence and humour in medical education. Such research promises to reveal more fully the contributions of silence and humour to socialisation in clinical training settings. © Blackwell Publishing Ltd 2013.

  4. RNA-Interference Components Are Dispensable for Transcriptional Silencing of the Drosophila Bithorax-Complex

    KAUST Repository

    Cernilogar, Filippo M.

    2013-06-13

    Background:Beyond their role in post-transcriptional gene silencing, Dicer and Argonaute, two components of the RNA interference (RNAi) machinery, were shown to be involved in epigenetic regulation of centromeric heterochromatin and transcriptional gene silencing. In particular, RNAi mechanisms appear to play a role in repeat induced silencing and some aspects of Polycomb-mediated gene silencing. However, the functional interplay of RNAi mechanisms and Polycomb group (PcG) pathways at endogenous loci remains to be elucidated.Principal Findings:Here we show that the endogenous Dicer-2/Argonaute-2 RNAi pathway is dispensable for the PcG mediated silencing of the homeotic Bithorax Complex (BX-C). Although Dicer-2 depletion triggers mild transcriptional activation at Polycomb Response Elements (PREs), this does not induce transcriptional changes at PcG-repressed genes. Moreover, Dicer-2 is not needed to maintain global levels of methylation of lysine 27 of histone H3 and does not affect PRE-mediated higher order chromatin structures within the BX-C. Finally bioinformatic analysis, comparing published data sets of PcG targets with Argonaute-2-bound small RNAs reveals no enrichment of these small RNAs at promoter regions associated with PcG proteins.Conclusions:We conclude that the Dicer-2/Argonaute-2 RNAi pathway, despite its role in pairing sensitive gene silencing of transgenes, does not have a role in PcG dependent silencing of major homeotic gene cluster loci in Drosophila. © 2013 Cernilogar et al.

  5. The Luteovirus P4 Movement Protein Is a Suppressor of Systemic RNA Silencing.

    Science.gov (United States)

    Fusaro, Adriana F; Barton, Deborah A; Nakasugi, Kenlee; Jackson, Craig; Kalischuk, Melanie L; Kawchuk, Lawrence M; Vaslin, Maite F S; Correa, Regis L; Waterhouse, Peter M

    2017-10-10

    The plant viral family Luteoviridae is divided into three genera: Luteovirus , Polerovirus and Enamovirus . Without assistance from another virus, members of the family are confined to the cells of the host plant's vascular system. The first open reading frame (ORF) of poleroviruses and enamoviruses encodes P0 proteins which act as silencing suppressor proteins (VSRs) against the plant's viral defense-mediating RNA silencing machinery. Luteoviruses, such as barley yellow dwarf virus-PAV (BYDV-PAV), however, have no P0 to carry out the VSR role, so we investigated whether other proteins or RNAs encoded by BYDV-PAV confer protection against the plant's silencing machinery. Deep-sequencing of small RNAs from plants infected with BYDV-PAV revealed that the virus is subjected to RNA silencing in the phloem tissues and there was no evidence of protection afforded by a possible decoy effect of the highly abundant subgenomic RNA3. However, analysis of VSR activity among the BYDV-PAV ORFs revealed systemic silencing suppression by the P4 movement protein, and a similar, but weaker, activity by P6. The closely related BYDV-PAS P4, but not the polerovirus potato leafroll virus P4, also displayed systemic VSR activity. Both luteovirus and the polerovirus P4 proteins also showed transient, weak local silencing suppression. This suggests that systemic silencing suppression is the principal mechanism by which the luteoviruses BYDV-PAV and BYDV-PAS minimize the effects of the plant's anti-viral defense.

  6. Apparent ploidy effects on silencing are post-transcriptional at HML and telomeres in Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Jenny M McLaughlan

    Full Text Available The repression of genes in regions of heterochromatin is known as transcriptional silencing. It occurs in a wide range of organisms and can have importance in adaptation to the environment, developmental changes and disease. The model organism Saccharomyces cerevisiae has been used for many years to study transcriptional silencing, but until recently no study has been made in relation to ploidy. The aim of this work was to compare transcriptional silencing in haploids and diploids at both telomeres and the hidden mating-type (HM loci. Transcriptional silencing was assayed, by growth on 5-fluoroorotic acid (5-FOA media or by flow cytometry, on strains where a telomere or HM locus was marked. RNA levels were measured by quantitative RT-PCR to confirm that effects were transcriptional. 5-FOA assays and flow cytometry were consistent with transcriptional silencing at telomeres and at HML being reduced as ploidy increases which agreed with conclusions in previous publications. However, QRT-PCR revealed that transcriptional silencing was unaffected by ploidy and thus protein levels were increasing independently of RNA levels. At telomere XI left (XI-L, changes in protein level were strongly influenced by mating-type, whereas at HML mating-type had much less influence. The post-transcriptional effects seen in this study, illustrate the often ignored need to measure RNA levels when assaying transcriptional silencing in Saccharomyces cerevisiae.

  7. ENHANCEMENTS TO NATURAL ATTENUATION: SELECTED CASE STUDIES

    Energy Technology Data Exchange (ETDEWEB)

    Vangelas, K; W. H. Albright, W; E. S. Becvar, E; C. H. Benson, C; T. O. Early, T; E. Hood, E; P. M. Jardine, P; M. Lorah, M; E. Majche, E; D. Major, D; W. J. Waugh, W; G. Wein, G; O. R. West, O

    2007-05-15

    In 2003 the US Department of Energy (DOE) embarked on a project to explore an innovative approach to remediation of subsurface contaminant plumes that focused on introducing mechanisms for augmenting natural attenuation to achieve site closure. Termed enhanced attenuation (EA), this approach has drawn its inspiration from the concept of monitored natural attenuation (MNA).

  8. Macroseismic intensity attenuation in Iran

    Science.gov (United States)

    Yaghmaei-Sabegh, Saman

    2018-01-01

    Macroseismic intensity data plays an important role in the process of seismic hazard analysis as well in developing of reliable earthquake loss models. This paper presents a physical-based model to predict macroseismic intensity attenuation based on 560 intensity data obtained in Iran in the time period 1975-2013. The geometric spreading and energy absorption of seismic waves have been considered in the proposed model. The proposed easy to implement relation describes the intensity simply as a function of moment magnitude, source to site distance and focal depth. The prediction capability of the proposed model is assessed by means of residuals analysis. Prediction results have been compared with those of other intensity prediction models for Italy, Turkey, Iran and central Asia. The results indicate the higher attenuation rate for the study area in distances less than 70km.

  9. Lack of pairing during meiosis triggers multigenerational transgene silencing in Caenorhabditis elegans

    Science.gov (United States)

    Leopold, Luciana E.; Heestand, Bree N.; Seong, Soobin; Shtessel, Ludmila; Ahmed, Shawn

    2015-01-01

    Single-copy transgenes in Caenorhabditis elegans can be subjected to a potent, irreversible silencing process termed small RNA-induced epigenetic silencing (RNAe). RNAe is promoted by the Piwi Argonaute protein PRG-1 and associated Piwi-interacting RNAs (piRNAs), as well as by proteins that promote and respond to secondary small interfering RNA (siRNA) production. Here we define a related siRNA-mediated silencing process, termed “multigenerational RNAe,” which can occur for transgenes that are maintained in a hemizygous state for several generations. We found that transgenes that contain either GFP or mCherry epitope tags can be silenced via multigenerational RNAe, whereas a transgene that possesses GFP and a perfect piRNA target site can be rapidly and permanently silenced via RNAe. Although previous studies have shown that PRG-1 is typically dispensable for maintenance of RNAe, we found that both initiation and maintenance of multigenerational RNAe requires PRG-1 and the secondary siRNA biogenesis protein RDE-2. Although silencing via RNAe is irreversible, we found that transgene expression can be restored when hemizygous transgenes that were silenced via multigenerational RNAe become homozygous. Furthermore, multigenerational RNAe was accelerated when meiotic pairing of the chromosome possessing the transgene was abolished. We propose that persistent lack of pairing during meiosis elicits a reversible multigenerational silencing response, which can lead to permanent transgene silencing. Multigenerational RNAe may be broadly relevant to single-copy transgenes used in experimental biology and to shaping the epigenomic landscape of diverse species, where genomic polymorphisms between homologous chromosomes commonly result in unpaired DNA during meiosis. PMID:25941370

  10. 5-Azacytidine mediated reactivation of silenced transgenes in potato (Solanum tuberosum) at the whole plant level.

    Science.gov (United States)

    Tyč, Dimitrij; Nocarová, Eva; Sikorová, Lenka; Fischer, Lukáš

    2017-08-01

    Transient 5-azacytidine treatment of leaf explants from potato plants with transcriptionally silenced transgenes allows de novo regeneration of plants with restored transgene expression at the whole plant level. Transgenes introduced into plant genomes frequently become silenced either at the transcriptional or the posttranscriptional level. Transcriptional silencing is usually associated with DNA methylation in the promoter region. Treatments with inhibitors of maintenance DNA methylation were previously shown to allow reactivation of transcriptionally silenced transgenes in single cells or tissues, but not at the whole plant level. Here we analyzed the effect of DNA methylation inhibitor 5-azacytidine (AzaC) on the expression of two silenced reporter genes encoding green fluorescent protein (GFP) and neomycin phosphotransferase (NPTII) in potato plants. Whereas no obvious reactivation was observed in AzaC-treated stem cuttings, transient treatment of leaf segments with 10 μM AzaC and subsequent de novo regeneration of shoots on the selective medium with kanamycin resulted in the production of whole plants with clearly reactivated expression of previously silenced transgenes. Reactivation of nptII expression was accompanied by a decrease in cytosine methylation in the promoter region of the gene. Using the plants with reactivated GFP expression, we found that re-silencing of this transgene can be accidentally triggered by de novo regeneration. Thus, testing the incidence of transgene silencing during de novo regeneration could be a suitable procedure for negative selection of transgenic lines (insertion events) which have an inclination to be silenced. Based on our analysis of non-specific inhibitory effects of AzaC on growth of potato shoots in vitro, we estimated that AzaC half-life in the culture media is approximately 2 days.

  11. Driving in unheard silence: Disability and the politics of shutting up.

    Science.gov (United States)

    Lourens, Heidi

    2018-03-01

    The politics of silence is central to disability experience and the field of disability studies. In this analytical autoethnography, I write about my silences as a visually impaired woman. I explore and make sense of personal life stories through a theoretical perspective. The analysis of these personal experiences lead me to argue that disability-related silences are mostly created through the confluence of inaccessible physical and social environments and the psychological internalisation of these worlds. I also discuss the ways in which I am currently regaining my voice. Further research on resistance by disabled persons is recommended.

  12. Empathy and silence in pastoral care for traumatic grief and loss.

    Science.gov (United States)

    Capretto, Peter

    2015-02-01

    This paper evaluates silence as a therapeutic practice in pastoral care for traumatic grief and loss. Informed by the history of attachment and mourning theory, its research considers the basic effect that empathy has upon the therapeutic relationship around psychic difference. The study appraises the potential resources and detriments that empathic language may have for the grief process. Offering clinical examples in hospice chaplaincy, it refutes the idea that silence is formulaic tool to be used. It instead offers silence as the acceptance of the limits of empathic language and the affirmation of psychological difference and theological wholeness.

  13. Inhibition of FSS-induced actin cytoskeleton reorganization by silencing LIMK2 gene increases the mechanosensitivity of primary osteoblasts.

    Science.gov (United States)

    Yang, Zhi; Tan, Shuyi; Shen, Yun; Chen, Rui; Wu, Changjing; Xu, Yajuan; Song, Zijun; Fu, Qiang

    2015-05-01

    Mechanical stimulation plays an important role in bone cell metabolic activity. However, bone cells lose their mechanosensitivity upon continuous mechanical stimulation (desensitization) and they can recover the sensitivity with insertion of appropriate rest period into the mechanical loading profiles. The concrete molecular mechanism behind the regulation of cell mechanosensitivity still remains unclear. As one kind of mechanosensitive cell to react to the mechanical stimulation, osteoblasts respond to fluid shear stress (FSS) with actin cytoskeleton reorganization, and the remodeling of actin cytoskeleton is closely associated with the alteration of cell mechanosensitivity. In order to find out whether inhibiting the actin cytoskeleton reorganization by silencing LIM-kinase 2 (LIMK2) gene would increase the mechanosensitivity of primary osteoblasts, we attenuated the formation of actin stress fiber under FSS in a more specific way: inhibiting the LIMK2 expression by RNA interference. We found that inhibition of LIMK2 expression by RNA interference attenuated the formation of FSS-induced actin stress fiber, and simultaneously maintained the integrity of actin cytoskeleton in primary osteoblasts. We confirmed that the decreased actin cytoskeleton reorganization in response to LIMK2 inhibition during FSS increased the mechanosensitivity of the osteoblasts, based on the increased c-Fos and COX-2 expression as well as the enhanced proliferative activity in response to FSS. These data suggest that osteoblasts can increase their mechanosensitivity under continuous mechanical stimulation by reducing the actin stress fiber formation through inhibiting the LIMK2 expression. This study provides us with a new and more specific method to regulate the osteoblast mechanosensitivity, and also a new therapeutic target to cure bone related diseases, which is of importance in maintaining bone mass and promoting osteogenesis. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Silence as an element of care: A meta-ethnographic review of professional caregivers' experience in clinical and pastoral settings.

    Science.gov (United States)

    Bassett, Lynn; Bingley, Amanda F; Brearley, Sarah G

    2018-01-01

    In interactions between professional caregivers, patients and family members at the end of life, silence often becomes more prevalent. Silence is acknowledged as integral to interpersonal communication and compassionate care but is also noted as a complex and ambiguous phenomenon. This review seeks interdisciplinary experience to deepen understanding of qualities of silence as an element of care. To search for published papers which describe professional caregivers' experience of silence as an element of care, in palliative and other clinical, spiritual and pastoral care settings and to synthesise their findings. Meta-ethnography: employing a systematic search strategy and line-of-argument synthesis. PsycINFO and seven other cross-disciplinary databases, supplemented by hand-search, review of reference lists and citation tracking. No date range was imposed. Inclusion criteria focused on reported experience of silence in professional caregiving. Selected papers ( n = 18) were appraised; none were rejected on grounds of quality. International, interdisciplinary research and opinion endorses the value of silence in clinical care. As a multi-functional element of interpersonal relationships, silence operates in partnership with speech to support therapeutic communication. As a caregiving practice, silence is perceived as particularly relevant in spiritual and existential dimensions of care when words may fail. Experience of silence as an element of care was found in palliative and spiritual care, psychotherapy and counselling supporting existing recognition of the value of silence as a skill and practice. Because silence can present challenges for caregivers, greater understanding may offer benefits for clinical practice.

  15. Le silence, ce cri qui résonne dans l’écriture de Viviane Forrester

    Directory of Open Access Journals (Sweden)

    Amelia Peral Crespo

    2015-11-01

    Full Text Available The Holocaust Literature is tied to Silence from its beginning as the writing to silence. Write about the Holocaust and relate the experiences lived in first person or transmit them to the coming generations means leaving the silence which, for years, was the ideal refuge. This research focuses on the literary production of Viviane Forrester. The different expressions of silence that characterize her writings are analyzed. Silence is the cry that underlies in the most profound of the human being that return from the concentration camps, as Lazarus from the dead. It is a silence that grows to a cry because Forrester’s writing, almost in parallel to the fragmentary writing of Blanchot, an-nounces livre à venir, expressing the cry in silence without the ending of the word

  16. Silence of long noncoding RNA PANDAR switches low-dose curcumin-induced senescence to apoptosis in colorectal cancer cells

    Directory of Open Access Journals (Sweden)

    Chen T

    2017-01-01

    Full Text Available Tao Chen,1,* Peng Yang,1,* Hui Wang,1 Zhen-Yu He2 1Department of General Surgery, The Second Clinical Medical College of Nanjing Medical University, 2Department of General Surgery, The Second Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China *These authors contributed equally to this work Abstract: Long noncoding RNAs (lncRNAs are emerging as having multiple roles in cancer progression. However, roles of lncRNAs in chemotherapy for colorectal cancer (CRC remain unclear. This study investigated the biological functions of lncRNA PANDAR in CRC cells treated with curcumin chemotherapy. Herein, we identified that PANDAR expression was not notably differential in CRC tissues compared with the corresponding normal tissues. Consistently, in vitro experiments revealed that knockdown of PANDAR could not change the proliferation, apoptosis, or senescence of CRC cells. Further analyses showed that low-dose curcumin could induce senescence in CRC cells without affecting cell apoptosis. Moreover, expression of PANDAR was increased in curcumin-treated CRC cells. Furthermore, silencing PANDAR in curcumin-treated cells increased apoptosis and greatly attenuated senescence possibly by stimulating the expression of PUMA. Together, these findings indicate that knockdown of lncRNA PANDAR switches curcumin-induced senescence to apoptosis, which may be potentially valuable in CRC therapy. Keywords: colorectal cancer, long noncoding RNA, PANDAR, curcumin, chemotherapy

  17. Silencing of NAC1 Expression Induces Cancer Cells Oxidative Stress in Hypoxia and Potentiates the Therapeutic Activity of Elesclomol

    Directory of Open Access Journals (Sweden)

    Yi-Jie Ren

    2017-11-01

    Full Text Available In order to survive under conditions of low oxygen, cancer cells can undergo a metabolic switch to glycolysis and suppress mitochondrial respiration in order to reduce oxygen consumption and prevent excessive amounts of reactive oxygen species (ROS production. Nucleus accumbens-1 (NAC1, a nuclear protein of the BTB/POZ gene family, has pivotal roles in cancer development. Here, we identified that NAC1-PDK3 axis as necessary for suppression of mitochondrial function, oxygen consumption, and more harmful ROS generation and protects cancer cells from apoptosis in hypoxia. We show that NAC1 mediates suppression of mitochondrial function in hypoxia through inducing expression of pyruvate dehydrogenase kinase 3 (PDK3 by HIF-1α at the transcriptional level, thereby inactivating pyruvate dehydrogenase and attenuating mitochondrial respiration. Re-expression of PDK3 in NAC1 absent cells rescued cells from hypoxia-induced metabolic stress and restored the activity of glycolysis in a xenograft mouse model, and demonstrated that silencing of NAC1 expression can enhance the antitumor efficacy of elesclomol, a pro-oxidative agent. Our findings reveal a novel mechanism by which NAC1 facilitates oxidative stress resistance during cancer progression, and chemo-resistance in cancer therapy.

  18. Preclinical Evaluation of a Lentiviral Vector for Huntingtin Silencing

    Directory of Open Access Journals (Sweden)

    Karine Cambon

    2017-06-01

    Full Text Available Huntington’s disease (HD is an autosomal dominant neurodegenerative disorder resulting from a polyglutamine expansion in the huntingtin (HTT protein. There is currently no cure for this disease, but recent studies suggest that RNAi to downregulate the expression of both normal and mutant HTT is a promising therapeutic approach. We previously developed a small hairpin RNA (shRNA, vectorized in an HIV-1-derived lentiviral vector (LV, that reduced pathology in an HD rodent model. Here, we modified this vector for preclinical development by using a tat-independent third-generation LV (pCCL backbone and removing the original reporter genes. We demonstrate that this novel vector efficiently downregulated HTT expression in vitro in striatal neurons derived from induced pluripotent stem cells (iPSCs of HD patients. It reduced two major pathological HD hallmarks while triggering a minimal inflammatory response, up to 6 weeks after injection, when administered by stereotaxic surgery in the striatum of an in vivo rodent HD model. Further assessment of this shRNA vector in vitro showed proper processing by the endogenous silencing machinery, and we analyzed gene expression changes to identify potential off-targets. These preclinical data suggest that this new shRNA vector fulfills primary biosafety and efficiency requirements for further development in the clinic as a cure for HD.

  19. Breaking the silence, dismantling taboos: Latino novels on AIDS.

    Science.gov (United States)

    Sandoval Sánchez, A

    1998-01-01

    As AIDS has ravaged the world in the last two decades, literature has played an important role in giving testimony of the epidemic. According to different communities and particular experiences, AIDS literature can offer ways of coping and surviving. In the last few years the U.S. Latino/a population has been highly affected by AIDS. The first genres to register AIDS were poetry and theatre. In this essay I examine how AIDS is represented in the first four Latino novels to deal with the subject matter: Ana Castillo's So Far from God, Daniel Torres's Morirás si da una primavera, Elías Miguel Muñoz's The Greatest Performance, and Jaime Manrique's latin Moon in Manhattan. My critical reading centers on how AIDS constitutes a new articulation of identity, particularly gay and ethnic identity. Most importantly, I propose that these novels contribute to dismantling homophobia and compulsory heterosexuality, deconstructing sexual and cultural taboos, and breaking the silence on AIDS/SIDA.

  20. Sox6 directly silences epsilon globin expression in definitive erythropoiesis.

    Directory of Open Access Journals (Sweden)

    2006-02-01

    Full Text Available Sox6 is a member of the Sox transcription factor family that is defined by the conserved high mobility group (HMG DNA binding domain, first described in the testis determining gene, Sry. Previous studies have suggested that Sox6 plays a role in the development of the central nervous system, cartilage, and muscle. In the Sox6-deficient mouse, p100H, epsilony globin is persistently expressed, and increased numbers of nucleated red cells are present in the fetal circulation. Transfection assays in GM979 (erythroleukemic cells define a 36-base pair region of the epsilony proximal promoter that is critical for Sox6 mediated repression. Electrophoretic mobility shift assay (EMSA and chromatin immunoprecipitation (ChIP assays demonstrate that Sox6 acts as a repressor by directly binding to the epsilony promoter. The normal expression of Sox6 in wild-type fetal liver and the ectopic expression of epsilony in p100H homozygous fetal liver demonstrate that Sox6 functions in definitive erythropoiesis. The present study shows that Sox6 is required for silencing of epsilony globin in definitive erythropoiesis and suggests a role for Sox6 in erythroid cell maturation. Thus, Sox6 regulation of epsilony globin might provide a novel therapeutical target in the treatment of hemoglobinopathies such as sickle cell anemia and thalassemia.

  1. Grandparents' experiences of childhood cancer, part 1: doubled and silenced.

    Science.gov (United States)

    Moules, Nancy J; Laing, Catherine M; McCaffrey, Graham; Tapp, Dianne M; Strother, Douglas

    2012-01-01

    In this study, the authors examined the experiences of grandparents who have had, or have, a grandchild with childhood cancer. Sixteen grandparents were interviewed using unstructured interviews, and the data were analyzed according to hermeneutic-phenomenological tradition, as guided by the philosophical hermeneutics of Hans-Georg Gadamer. Interpretive findings indicate that grandparents suffer and worry in many complex ways that include a doubled worry for their own children as well as their grandchildren. According to the grandparents in this study, this worry was, at times, silenced in efforts to protect the parents of the grandchild from the burden of concern for the grandparent. Other interpretations include the nature of having one's universe shaken, of having lives put on hold, and a sense of helplessness. The grandparents in this study offer advice to other grandparents as well as to the health care system regarding what kinds of things might have been more helpful to them as one level of the family system, who, like other subsystems of the family, are also profoundly affected by the event of childhood cancer.

  2. Nature to the natural rescue: Silencing microbial chats.

    Science.gov (United States)

    Paul, Diby; Gopal, Judy; Kumar, Manish; Manikandan, Muthu

    2018-01-25

    Communication is the sole means by which effective networking and co-existence is accomplished amongst living beings. Microbes have their own chit-chats. Science has overheard these microbial gossips and have concluded that these aren't just informal communications, but carefully coordinated signals that plan their effective strategies. Tracking one such signal molecule, N-acyl homoserine lactone (AHL), led to a fundamental understanding to microbial quorum sensing (QS). Furtherance of research sought for ways to cut off communication between these virulent forms, so as to hinder their combinatorial attacks through quorum sensing inhibitors (QSIs). A clear understanding of the inhibitors of these microbial communication systems is vital to destroy their networking and co-working. The current review, consolidates the solutions for QSIs offered from natural sources against these micro components, that are capable of slaughtering even nature's most fit entity-man. The applications of effective out sourcing of this QSI technologies and the need for development are discussed. The importance of silencing this microbial chatter to various aspects of human life and their implications are discussed and elaborated. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Silence in liturgy as the space for the Holy Ghost’s activity

    Directory of Open Access Journals (Sweden)

    Adelajda Sielepin

    2006-06-01

    Full Text Available The aim of this article is to clarify the essential and often neglected function of liturgical silence. In practice silence is usually intended to prepare the participants for listening or reflecting upon the word, especially when proclaimed by the minister. Whereas it is vital to know that silence constitutes a creative element of the liturgy, because the involvement of the Holy Spirit. In His action and cooperation with the participants He enables them to get into communion with Christ the Word and the Person and eventually to join effectively His mission. In that sense silence helps the Holy Ghost to fulfill His function in continuing the dialogue between God and man as well as in enhancing one’s spiritual skills for the fruitful participation in the Mystery of Christ and the Church.

  4. Reticence in Silence. An Examination of Heidegger's Phenomenology of Language in Contributions to Philosophy

    Czech Academy of Sciences Publication Activity Database

    Nitsche, Martin

    2011-01-01

    Roč. 765, č. 1 (2011), s. 74-79 ISSN 1407-2157 Institutional research plan: CEZ:AV0Z90090514 Keywords : Heidegger * contributions to philosophy * phenomenology * language * reticence in silence Subject RIV: AA - Philosophy ; Religion

  5. Viral suppressors of RNA silencing hinder exogenous and endogenous small RNA pathways in Drosophila.

    Directory of Open Access Journals (Sweden)

    Bassam Berry

    2009-06-01

    Full Text Available 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.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.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.

  6. 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.

  7. Identifying Silence Climate in Organizations in the Framework of Contemporary Management Approaches

    Directory of Open Access Journals (Sweden)

    Mustafa Emre Civelek

    2015-10-01

    Full Text Available Dynamic competition conditions in present day, bring about the consequence for businesses to face varied problems with each passing day. At this point, current management approaches include studies that would shed light on the new problems of businesses. Organizational Silence, a concept that has recently been being voiced in business world, has come up in such context. Organizational silence could be expressed as the employee behavior of keeping silent about certain negativities due to various reasons in an organization. Since knowledge sharing in modern organizations is of capital importance in terms of responding hastily to the changes in a competitive environment, spread of this behavior of employees to organization culture and climate presents a threat of indifference. In this study, the concept of Organizational Silence is defined and the effects of conceived silence climate on management of organizations are discussed.

  8. Identifying Silence Climate in Organizations in the Framework of Contemporary Management Approaches

    Directory of Open Access Journals (Sweden)

    Mustafa Emre Civelek

    2015-12-01

    Full Text Available Dynamic competition conditions in present day bring about the consequence for businesses to face varied problems with each passing day. At this point, current management approaches include studies that would shed light on the new problems of businesses. Organizational Silence, a concept that has recently been being voiced in business world, has come up in such context. Organizational silence could be expressed as the employee behavior of keeping silent about certain negativities due to various reasons in an organization. Since knowledge sharing in modern organizations is of capital importance in terms of responding hastily to the changes in a competitive environment, spread of this behavior of employees to organization culture and climate presents a threat of indifference. In this study, the concept of Organizational Silence is defined and the effects of conceived silence climate on management of organizations are discussed.

  9. The Heterologous Expression of the p22 RNA Silencing Suppressor of the Crinivirus Tomato Chlorosis Virus from Tobacco Rattle Virus and Potato Virus X Enhances Disease Severity but Does Not Complement Suppressor-Defective Mutant Viruses.

    Science.gov (United States)

    Landeo-Ríos, Yazmín; Navas-Castillo, Jesús; Moriones, Enrique; Cañizares, M. Carmen

    2017-11-24

    To counteract host antiviral RNA silencing, plant viruses express suppressor proteins that function as pathogenicity enhancers. The genome of the Tomato chlorosis virus (ToCV) (genus Crinivirus , family Closteroviridae ) encodes an RNA silencing suppressor, the protein p22, that has been described as having one of the longest lasting local suppressor activities when assayed in Nicotiana benthamiana . Since suppression of RNA silencing and the ability to enhance disease severity are closely associated, we analyzed the effect of expressing p22 in heterologous viral contexts. Thus, we studied the effect of the expression of ToCV p22 from viral vectors Tobacco rattle virus (TRV) and Potato virus X (PVX), and from attenuated suppressor mutants in N. benthamiana plants. Our results show that although an exacerbation of disease symptoms leading to plant death was observed in the heterologous expression of ToCV p22 from both viruses, only in the case of TRV did increased viral accumulation occur. The heterologous expression of ToCV p22 could not complement suppressor-defective mutant viruses.

  10. Attenuation of Maladaptive Responses in Aortic Adventitial Fibroblasts through Stimuli-Triggered siRNA Release from Lipid-Polymer Nanocomplexes.

    Science.gov (United States)

    Greco, Chad T; Akins, Robert E; Epps, Thomas H; Sullivan, Millicent O

    2017-08-01

    Lipid-siRNA assemblies are modified with photo-responsive polymers to enable spatiotemporally-controlled silencing of interleukin 1 beta (IL1β) and cadherin 11 (CDH11), two genes that are essential drivers of maladaptive responses in human aortic adventitial fibroblasts (AoAFs). These hybrid nanocomplexes address the critical challenge of locally mitigating fibrotic actions that lead to the high rates of vascular graft failures. In particular, the lipid-polymer formulations provide potent silencing of IL1β and CDH11 that is precisely modulated by a photo-release stimulus. Moreover, a dynamic modeling framework is used to design a multi-dose siRNA regimen that sustains knockdown of both genes over clinically-relevant timescales. Multi-dose suppression illuminates a cooperative role for IL1β and CDH11 in pathogenic adventitial remodeling and is directly linked to desirable functional outcomes. Specifically, myofibroblast differentiation and cellular proliferation, two of the primary hallmarks of fibrosis, are significantly attenuated by IL1β silencing. Meanwhile, the effects of CDH11 siRNA treatment on differentiation become more pronounced at higher cell densities characteristic of constrictive adventitial remodeling in vivo . Thus, this work offers a unique formulation design for photo-responsive gene suppression in human primary cells and establishes a new dosing method to satisfy the critical need for local attenuation of fibrotic responses in the adventitium surrounding vascular grafts.

  11. Dissection of tomato lycopene biosynthesis through virus-induced gene silencing.

    Science.gov (United States)

    Fantini, Elio; Falcone, Giulia; Frusciante, Sarah; Giliberto, Leonardo; Giuliano, Giovanni

    2013-10-01

    Lycopene biosynthesis in tomato (Solanum lycopersicum) fruits has been proposed to proceed through a poly-cis pathway catalyzed by phytoene synthase (PSY), two desaturases (phytoene desaturase [PDS] and ζ-carotene desaturase [ZDS]), and two cis-trans isomerases (ζ-carotene isomerase [ZISO] and prolycopene isomerase [CrtISO]). The mechanism of action of these enzymes has been studied in Escherichia coli, but a systematic study of their in vivo function is lacking. We studied the function of nine candidate genes (PSY1, PSY2, PSY3, PDS, ZDS, ZISO, CrtISO, CrtISO-Like1, and CrtISO-Like2) using virus-induced gene silencing (VIGS) coupled to high-resolution liquid chromatography coupled with diode array detector and mass spectrometry, which allowed the identification and quantitation of 45 different carotenoid isomers, including linear xanthophylls. The data confirm the confinement of the VIGS signal to the silenced fruits and the similarity of the phenotypes of PSY1- and CrtISO-silenced fruits with those of the yellow flesh and tangerine mutants. Light was able to restore lycopene biosynthesis in ZISO-silenced fruits. Isomeric composition of fruits silenced at different metabolic steps suggested the existence of three functional units, comprising PSY1, PDS/ZISO, and ZDS/CrtISO, and responsible for the synthesis of 15-cis-phytoene, 9,9'-di-cis-ζ-carotene, and all-trans-lycopene, respectively. Silencing of a desaturase (PDS or ZDS) resulted in the induction of the isomerase in the same functional unit (ZISO or CrtISO, respectively). All-trans-ζ-carotene was detectable in nonsilenced fruits, greatly increased in ZDS-silenced ones, and disappeared in CrtISO-Like1-/CrtISO-Like2-silenced ones, suggesting the existence of a metabolic side branch, comprising this compound and initiated by the latter enzymes.

  12. 'Checkmating HIV&AIDS': Using chess to break the silence in the ...

    African Journals Online (AJOL)

    Omar Esau

    2012-12-13

    Dec 13, 2012 ... Keywords: HIV&AIDS, action research, chess, checkmating, culture of silence, prevention, awareness. Résumé. Cet article est un compte rendu de mon projet de recherche-action « mettre le VIH/SIDA échec et mat », qui avait pour but de briser dans ma classe la « culture du silence » au sujet du VIH/SIDA ...

  13. Silencing of the rotavirus NSP4 protein decreases the incidence of biliary atresia in murine model.

    Directory of Open Access Journals (Sweden)

    Jiexiong Feng

    Full Text Available Biliary atresia is a common disease in neonates which causes obstructive jaundice and progressive hepatic fibrosis. Our previous studies indicate that rotavirus infection is an initiator in the pathogenesis of experimental biliary atresia (BA through the induction of increased nuclear factor-kappaB and abnormal activation of the osteopontin inflammation pathway. In the setting of rotavirus infection, rotavirus nonstructural protein 4 (NSP4 serves as an important immunogen, viral protein 7 (VP7 is necessary in rotavirus maturity and viral protein 4 (VP4 is a virulence determiner. The purpose of the current study is to clarify the roles of NSP4, VP7 and VP4 in the pathogenesis of experimental BA. Primary cultured extrahepatic biliary epithelia were infected with Rotavirus (mmu18006. Small interfering RNA targeting NSP4, VP7 or VP4 was transfected before rotavirus infection both in vitro and in vivo. We analyzed the incidence of BA, morphological change, morphogenesis of viral particles and viral mRNA and protein expression. The in vitro experiments showed NSP4 silencing decreased the levels of VP7 and VP4, reduced viral particles and decreased cytopathic effect. NSP4-positive cells had strongly positive expression of integrin subunit α2. Silencing of VP7 or VP4 partially decreased epithelial injury. Animal experiments indicated after NSP4 silencing, mouse pups had lower incidence of BA than after VP7 or VP4 silencing. However, 33.3% of VP4-silenced pups (N = 6 suffered BA and 50% of pups (N = 6 suffered biliary injury after VP7 silencing. Hepatic injury was decreased after NSP4 or VP4 silencing. Neither VP4 nor VP7 were detected in the biliary ducts after NSP4. All together, NSP4 silencing down-regulates VP7 and VP4, resulting in decreased incidence of BA.

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

    Directory of Open Access Journals (Sweden)

    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

  15. Synthetic RNA Silencing in Bacteria – Antimicrobial Discovery and Resistance Breaking

    OpenAIRE

    Good, Liam; Stach, James E. M.

    2011-01-01

    The increasing incidence and prevalence of antibiotic resistance in bacteria threatens the “antibiotic miracle.” Conventional antimicrobial drug development has failed to replace the armamentarium needed to combat this problem, and novel solutions are urgently required. Here we review both natural and synthetic RNA silencing and its potential to provide new antibacterials through improved target selection, evaluation, and screening. Furthermore, we focus on synthetic RNA silencers as a novel ...

  16. Organizational Silence, from Roots to Solutions: A Case Study in Iran Petroleum Industry

    Directory of Open Access Journals (Sweden)

    Mehdi Afkhami Ardakani

    2015-05-01

    Full Text Available Organizational silence is defined as the lack of effective interactions among staff and it stands opposite to the concept of organizational voice. In the present research, the purpose is to measure the silence behavior among the Research Institute of Petroleum Industry (RIPI staff before and after the implementation of a comprehensive suggestion system. A suggestion system is an internal structure easily accessed by all the staff to state their suggestions in a pre-structured format. The roots of silence behavior are studied based on a deep literature review to find out possible solutions to improve organizational voice. To conduct the research, a self-structured questionnaire has been developed and distributed among all the staff. A quasi-experimental methodology has been adopted to compare pretest and post-test results of silence status before and after implementing the suggestion system. The results show that the silence behavior has been meaningfully reduced. This is based on a simple t-test performed by SPSS software, where there is a meaningful difference between the silence status of pre-test and post-test. In other words, a suggestion system could be a communication opportunity to encourage staff to provide suggestions and to cooperate for promoting the organization, which will finally reduce the organization silence. A major gap within the studies of Iranian scholars about organizational silence is the failure to introduce effective solutions to reduce it. However, this research is innovative in the sense that it fills the mentioned gap. This research shows that large scale organizations like RIPI need to consider methods like suggestion systems to break bureaucratic obstacles so that their staff can easily find open routes to share their ideas and suggestions in a prestructured format. This cooperating will lead to mutual benefits for both parts, since suggestions could be used to enhance organizational structure and performance and

  17. Virus-Induced Gene Silencing as a Tool to Study Tomato Fruit Biochemistry.

    Science.gov (United States)

    Fantini, Elio; Giuliano, Giovanni

    2016-01-01

    Virus-Induced Gene Silencing (VIGS) is an excellent reverse genetic tool for the study of gene function in plants, based on virus infection. In this chapter, we describe a high-throughput approach based on VIGS for the study of tomato fruit biochemistry. It comprises the selection of the sequence for silencing using bioinformatics tools, the cloning of the fragment in the Tobacco Rattle Virus (TRV), and the agroinfiltration of tomato fruits mediated by Agrobacterium tumefaciens.

  18. Virus-induced gene silencing and Agrobacterium tumefaciens-mediated transient expression in Nicotiana tabacum.

    Science.gov (United States)

    Zhang, Zhao; Thomma, Bart P H J

    2014-01-01

    Virus-induced gene silencing (VIGS) is a rapid method for transient silencing of plant genes. In this chapter, we describe the methodology for Tobacco rattle virus (TRV)-based VIGS in Nicotiana tabacum. In combination with subsequent co-expression of the tomato immune receptor Ve1 and the corresponding Verticillium effector Ave1 through Agrobacterium tumefaciens-mediated transient transformation (agroinfiltration), we established a rapid system for assessing the requirement of candidate plant genes for Ve1-mediated immune signaling.

  19. Frequency Dependent Attenuation in Rocks

    Science.gov (United States)

    1990-01-20

    WORK UNIT ELEMENT NO NO NO ACCESSION NO 62714E 7A10 DA DA 1𔃻 T. ,E (Incude Security Clasification ) Frequency Dependent Attenuation in Rocks Ŗ 0E;SO’.A_...P., and L. Peselnick, Investigation of internal friction in fused quartz, steel , plexiglass, and Westerly granite from 0.01 to 1.00 Hertz at 10- to 10...P., and L. Peselnick, Investigation of internal friction in fused quartz, steel , plexiglas, and Westerly granite from 0.01 to 1.00 Hertz at 10-8 to 10

  20. Keap1 silencing boosts lipopolysaccharide-induced transcription of interleukin 6 via activation of nuclear factor κB in macrophages

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Peng [Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing (China); Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709 (United States); Xue, Peng; Dong, Jian [Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709 (United States); Peng, Hui [Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709 (United States); Evaluation and Research Center for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences (China); Clewell, Rebecca [Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709 (United States); Wang, Aiping [Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing (China); Wang, Yue [Institute for Medical Device Standardization Administration, National Institutes for Food and Drug Control, Beijing (China); Peng, Shuangqing [Evaluation and Research Center for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences (China); Qu, Weidong [Key Laboratory of the Public Health Safety, Ministry of Education, School of Public Health, Fudan University, Shanghai (China); Zhang, Qiang; Andersen, Melvin E. [Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709 (United States); Pi, Jingbo, E-mail: jpi@thehamner.org [Institute for Chemical Safety Sciences, The Hamner Institutes for Health Sciences, 6 Davis Drive, Research Triangle Park, NC 27709 (United States)

    2013-11-01

    Interleukin-6 (IL6) is a multifunctional cytokine that regulates immune and inflammatory responses. Multiple transcription factors, including nuclear factor κB (NF-κB) and nuclear factor E2-related factor 2 (Nrf2), regulate IL6 transcription. Kelch-like ECH-associated protein 1 (Keap1) is a substrate adaptor protein for the Cullin 3-dependent E3 ubiquitin ligase complex, which regulates the degradation of many proteins, including Nrf2 and IκB kinase β (IKKβ). Here, we found that stable knockdown of Keap1 (Keap1-KD) in RAW 264.7 (RAW) mouse macrophages and human monocyte THP-1 cells significantly increased expression of Il6, and Nrf2-target genes, under basal and lipopolysaccharide (LPS, 0.001–0.1 μg/ml)-challenged conditions. However, Nrf2 activation alone, by tert-butylhydroquinone treatment of RAW cells, did not increase expression of Il6. Compared to cells transduced with scrambled non-target negative control shRNA, Keap1-KD RAW cells showed enhanced protein levels of IKKβ and increased expression and phosphorylation of NF-κB p65 under non-stressed and LPS-treated conditions. Because the expression of Il6 in Keap1-KD RAW cells was significantly attenuated by silencing of Ikkβ, but not Nrf2, it appears that stabilized IKKβ is responsible for the enhanced transactivation of Il6 in Keap1-KD cells. This study demonstrated that silencing of Keap1 in macrophages boosts LPS-induced transcription of Il6 via NF-κB activation. Given the importance of IL6 in the inflammatory response, the Keap1–IKKβ–NF-κB pathway may be a novel target for treatment and prevention of inflammation and associated disorders. - Highlights: • Knockdown of Keap1 increases expression of Il6 in macrophages. • Silencing of Keap1 results in protein accumulation of IKKβ and NF-κB p65. • Induction of Il6 resulting from Keap1 silencing is attributed to NF-κB activation.

  1. The molecular basis for stability of heterochromatin-mediated silencing in mammals

    Directory of Open Access Journals (Sweden)

    Hiragami-Hamada Kyoko

    2009-11-01

    Full Text Available Abstract The archetypal epigenetic phenomenon of position effect variegation (PEV in Drosophila occurs when a gene is brought abnormally close to heterochromatin, resulting in stochastic silencing of the affected gene in a proportion of cells that would normally express it. PEV has been instrumental in unraveling epigenetic mechanisms. Using an in vivo mammalian model for PEV we have extensively investigated the molecular basis for heterochromatin-mediated gene silencing. Here we distinguish 'epigenetic effects' from other cellular differences by studying ex vivo cells that are identical, apart from the expression of the variegating gene which is silenced in a proportion of the cells. By separating cells according to transgene expression we show here that silencing appears to be associated with histone H3 lysine 9 trimethylation (H3K9me3, DNA methylation and the localization of the silenced gene to a specific nuclear compartment enriched in these modifications. In contrast, histone H3 acetylation (H3Ac and lysine 4 di or tri methylation (H3K4me2/3 are the predominant modifications associated with expression where we see the gene in a euchromatic compartment. Interestingly, DNA methylation and inaccessibility, rather than H3K9me3, correlated most strongly with resistance to de-repression by cellular activation. These results have important implications for understanding the contribution of specific factors involved in the establishment and maintenance of gene silencing and activation in vivo.

  2. 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.

  3. Strategy of gene silencing in cassava for validation of resistance genes

    International Nuclear Information System (INIS)

    Cortes, Simon; Lopez, Camilo

    2010-01-01

    Cassava (Manihot esculenta) is a major source of food for more than 1000 million people in the world and constitutes an important staple crop. Cassava bacterial blight, caused by the gram negative bacterium Xanthomonas axonopodis pv. manihotis, is one of the most important constraints for this crop. A candidate resistance gene against cassava bacterial blight, named RXam1, has been identified previously. In this work, we employed the gene silencing approach using the African cassava mosaic virus (ACMV) to validate the function of the RXam1 gene. We used as positive control the su gen, which produce photo blanching in leaves when is silenced. Plants from the SG10735 variety were bombardment with the ACMV-A-SU+ACMV-B y ACMV-A-RXam1+ACMV-B constructions. The silencing efficiency employing the su gene was low, only one of seven plants showed photo blanching. In the putative silenced plants for the RXam1 gene, no presence of siRNAs corresponding to RXam1 was observed; although a low diminution of the RXam1 gene expression was obtained. The growth curves for the Xam strain CIO136 in cassava plants inoculated showing a little but no significance difference in the susceptibility in the silenced plants compared to not silenced

  4. Silencing of the FRO1 gene and its effects on iron partition in Nicotiana benthamiana.

    Science.gov (United States)

    Gama, Florinda; Saavedra, Teresa; Dandlen, Susana; de Varennes, Amarilis; Correia, Pedro J; Pestana, Maribela; Nolasco, Gustavo

    2017-05-01

    To evaluate the dynamic role of the ferric-chelate reductase enzyme (FCR) and to identify possible pathways of regulation of its activity in different plant organs an investigation was conducted by virus-induced gene silencing (VIGS) using tobacco rattle virus (TRV) to silence the ferric reductase oxidase gene (FRO1) that encodes the FCR enzyme. Half of Nicotiana benthamiana plants received the VIGS vector and the rest remained as control. Four treatments were imposed: two levels of Fe in the nutrient solution (0 or 2.5 μM of Fe), each one with silenced or non-silenced (VIGS-0; VIGS-2.5) plants. Plants grown without iron (0; VIGS-0) developed typical symptoms of iron deficiency in the youngest leaves. To prove that FRO1 silencing had occurred, resupply of Fe (R) was done by adding 2.5 μM of Fe to the nutrient solution in a subset of chlorotic plants (0-R; VIGS-R). Twelve days after resupply, 0-R plants had recovered from Fe deficiency while plants containing the VIGS vector (VIGS-R) remained chlorotic and both FRO1 gene expression and FCR activity were considerably reduced, consequently preventing Fe uptake. With the VIGS technique we were able to silence the FRO1 gene in N. benthamiana and point out its importance in chlorophyll synthesis and Fe partition. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  5. On the role of RNA silencing in the pathogenicity and evolution of viroids and viral satellites

    Science.gov (United States)

    Wang, Ming-Bo; Bian, Xue-Yu; Wu, Li-Min; Liu, Li-Xia; Smith, Neil A.; Isenegger, Daniel; Wu, Rong-Mei; Masuta, Chikara; Vance, Vicki B.; Watson, John M.; Rezaian, Ali; Dennis, Elizabeth S.; Waterhouse, Peter M.

    2004-01-01

    Viroids and most viral satellites have small, noncoding, and highly structured RNA genomes. How they cause disease symptoms without encoding proteins and why they have characteristic secondary structures are two longstanding questions. Recent studies have shown that both viroids and satellites are capable of inducing RNA silencing, suggesting a possible role of this mechanism in the pathology and evolution of these subviral RNAs. Here we show that preventing RNA silencing in tobacco, using a silencing suppressor, greatly reduces the symptoms caused by the Y satellite of cucumber mosaic virus. Furthermore, tomato plants expressing hairpin RNA, derived from potato spindle tuber viroid, developed symptoms similar to those of potato spindle tuber viroid infection. These results provide evidence suggesting that viroids and satellites cause disease symptoms by directing RNA silencing against physiologically important host genes. We also show that viroid and satellite RNAs are significantly resistant to RNA silencing-mediated degradation, suggesting that RNA silencing is an important selection pressure shaping the evolution of the secondary structures of these pathogens. PMID:14978267

  6. SEISMIC ATTENUATION FOR RESERVOIR CHARACTERIZATION

    Energy Technology Data Exchange (ETDEWEB)

    Joel Walls; M.T. Taner; Naum Derzhi; Gary Mavko; Jack Dvorkin

    2003-12-01

    We have developed and tested technology for a new type of direct hydrocarbon detection. The method uses inelastic rock properties to greatly enhance the sensitivity of surface seismic methods to the presence of oil and gas saturation. These methods include use of energy absorption, dispersion, and attenuation (Q) along with traditional seismic attributes like velocity, impedance, and AVO. Our approach is to combine three elements: (1) a synthesis of the latest rock physics understanding of how rock inelasticity is related to rock type, pore fluid types, and pore microstructure, (2) synthetic seismic modeling that will help identify the relative contributions of scattering and intrinsic inelasticity to apparent Q attributes, and (3) robust algorithms that extract relative wave attenuation attributes from seismic data. This project provides: (1) Additional petrophysical insight from acquired data; (2) Increased understanding of rock and fluid properties; (3) New techniques to measure reservoir properties that are not currently available; and (4) Provide tools to more accurately describe the reservoir and predict oil location and volumes. These methodologies will improve the industry's ability to predict and quantify oil and gas saturation distribution, and to apply this information through geologic models to enhance reservoir simulation. We have applied for two separate patents relating to work that was completed as part of this project.

  7. Chlorine signal attenuation in concrete.

    Science.gov (United States)

    Naqvi, A A; Maslehuddin, M; Ur-Rehman, Khateeb; Al-Amoudi, O S B

    2015-11-01

    The intensity of prompt gamma-ray was measured at various depths from chlorine-contaminated silica fume (SF) concrete slab concrete specimens using portable neutron generator-based prompt gamma-ray setup. The intensity of 6.11MeV chloride gamma-rays was measured from the chloride contaminated slab at distance of 15.25, 20.25, 25.25, 30.25 and 35.25cm from neutron target in a SF cement concrete slab specimens. Due to attenuation of thermal neutron flux and emitted gamma-ray intensity in SF cement concrete at various depths, the measured intensity of chlorine gamma-rays decreases non-linearly with increasing depth in concrete. A good agreement was noted between the experimental results and the results of Monte Carlo simulation. This study has provided useful experimental data for evaluating the chloride contamination in the SF concrete utilizing gamma-ray attenuation method. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Silencing Huntington's chorea: Is RNA Interference a Potential Cure?

    Directory of Open Access Journals (Sweden)

    Gerlinde A. Metz

    2006-01-01

    Full Text Available In 1872, George Huntington described Huntington's disease as characterized by motor, cognitive and psychiatric impairments. Huntington's disease is a dominant and autosomal mutation on chromosome 4 featuring the insertion of numerous CAG repeats. CAG codes for the amino acid, glutmanine that forms part of the Huntingtin protein (htt. Excess glutamine attachments make htt prone to accumulate in neurons. Three genes can be considered when developing therapies for Huntington's disease. They include targeting the symptoms of the disease, the progression of the disease and the cause of the disease. By using RNA interference (RNAi, the cause of the disease can be targeted. RNAi is a method that could potentially silence the formation of abnormal htt. This paper will discuss how RNAi could potentially cure Huntington's disease, by describing the genetic and proteinomic basis of Huntington's disease, the function of RNAi in Huntington's disease and the problems of benefits of RNAi. Preliminary work using RNAi in transgenic mice has shown a decrease in the behavioural expression of the mutant Huntington gene. There are several limitations associated with using RNAi as a gene therapy. For example, the effects of RNAi are short lived. A transposition system such as Sleeping Beauty can be used to increase the integration of the gene, however, for patients who currently have Huntington's disease, RNAi may potentially be used in combination with drugs or other treatments to target both symptoms and the underlying cause of Huntington's disease. This combination could eventually alleviate many painful symptoms associated with Huntington's disease and could even stop the progressive neurodegeneration of Huntington's disease. This review concludes that a substantial amount of new research is still necessary before RNAi is directly applicable to human patients with Huntington's disease.

  9. Silencing by H-NS potentiated the evolution of Salmonella.

    Directory of Open Access Journals (Sweden)

    Sabrina S Ali

    2014-11-01

    Full Text Available The bacterial H-NS protein silences expression from sequences with higher AT-content than the host genome and is believed to buffer the fitness consequences associated with foreign gene acquisition. Loss of H-NS results in severe growth defects in Salmonella, but the underlying reasons were unclear. An experimental evolution approach was employed to determine which secondary mutations could compensate for the loss of H-NS in Salmonella. Six independently derived S. Typhimurium hns mutant strains were serially passaged for 300 generations prior to whole genome sequencing. Growth rates of all lineages dramatically improved during the course of the experiment. Each of the hns mutant lineages acquired missense mutations in the gene encoding the H-NS paralog StpA encoding a poorly understood H-NS paralog, while 5 of the mutant lineages acquired deletions in the genes encoding the Salmonella Pathogenicity Island-1 (SPI-1 Type 3 secretion system critical to invoke inflammation. We further demonstrate that SPI-1 misregulation is a primary contributor to the decreased fitness in Salmonella hns mutants. Three of the lineages acquired additional loss of function mutations in the PhoPQ virulence regulatory system. Similarly passaged wild type Salmonella lineages did not acquire these mutations. The stpA missense mutations arose in the oligomerization domain and generated proteins that could compensate for the loss of H-NS to varying degrees. StpA variants most able to functionally substitute for H-NS displayed altered DNA binding and oligomerization properties that resembled those of H-NS. These findings indicate that H-NS was central to the evolution of the Salmonellae by buffering the negative fitness consequences caused by the secretion system that is the defining characteristic of the species.

  10. Virus-induced gene silencing (VIGS) in Nicotiana benthamiana and tomato.

    Science.gov (United States)

    Velásquez, André C; Chakravarthy, Suma; Martin, Gregory B

    2009-06-10

    RNA interference (RNAi) is a highly specific gene-silencing phenomenon triggered by dsRNA. This silencing mechanism uses two major classes of RNA regulators: microRNAs, which are produced from non-protein coding genes and short interfering RNAs (siRNAs). Plants use RNAi to control transposons and to exert tight control over developmental processes such as flower organ formation and leaf development. Plants also use RNAi to defend themselves against infection by viruses. Consequently, many viruses have evolved suppressors of gene silencing to allow their successful colonization of their host. Virus-induced gene silencing (VIGS) is a method that takes advantage of the plant RNAi-mediated antiviral defense mechanism. In plants infected with unmodified viruses the mechanism is specifically targeted against the viral genome. However, with virus vectors carrying sequences derived from host genes, the process can be additionally targeted against the corresponding host mRNAs. VIGS has been adapted for high-throughput functional genomics in plants by using the plant pathogen Agrobacterium tumefaciens to deliver, via its Ti plasmid, a recombinant virus carrying the entire or part of the gene sequence targeted for silencing. Systemic virus spread and the endogenous plant RNAi machinery take care of the rest. dsRNAs corresponding to the target gene are produced and then cleaved by the ribonuclease Dicer into siRNAs of 21 to 24 nucleotides in length. These siRNAs ultimately guide the RNA-induced silencing complex (RISC) to degrade the target transcript. Different vectors have been employed in VIGS and one of the most frequently used is based on tobacco rattle virus (TRV). TRV is a bipartite virus and, as such, two different A. tumefaciens strains are used for VIGS. One carries pTRV1, which encodes the replication and movement viral functions while the other, pTRV2, harbors the coat protein and the sequence used for VIGS. Inoculation of Nicotiana benthamiana and tomato seedlings

  11. Estimating Rain Attenuation In Satellite Communication Links

    Science.gov (United States)

    Manning, R. M.

    1991-01-01

    Attenuation computed with help of statistical model and meteorological data. NASA Lewis Research Center Satellite Link Attenuation Model (SLAM) program QuickBASIC computer program evaluating static and dynamic statistical assessment of impact of rain attenuation on communication link established between Earth terminal and geosynchronous satellite. Application in specification, design, and assessment of satellite communication links for any terminal location in continental United States. Written in Microsoft QuickBASIC.

  12. Attenuation correction in SPECT images using attenuation map estimation with its emission data

    Science.gov (United States)

    Tavakoli, Meysam; Naji, Maryam; Abdollahi, Ali; Kalantari, Faraz

    2017-03-01

    Photon attenuation during SPECT imaging significantly degrades the diagnostic outcome and the quantitative accuracy of final reconstructed images. It is well known that attenuation correction can be done by using iterative reconstruction methods if we access to attenuation map. Two methods have been used to calculate the attenuation map: transmission-based and transmissionless techniques. In this phantom study, we evaluated the importance of attenuation correction by quantitative evaluation of errors associated with each method. For transmissionless approach, the attenuation map was estimated from the emission data only. An EM algorithm with attenuation model was developed and used for attenuation correction during image reconstruction. Finally, a comparison was done between reconstructed images using our OSEM code and analytical FBP method before and after attenuation correction. The results of measurements showed that: our programs are capable to reconstruct SPECT images and correct the attenuation effects. Moreover, to evaluate reconstructed image quality before and after attenuation correction we applied a novel approach using Image Quality Index. Attenuation correction increases the quality and quantitative accuracy in both methods. This increase is independent of activity in quantity factor and decreases with activity in quality factor. In EM algorithm, it is necessary to use regularization to obtain true distribution of attenuation coefficients.

  13. Noiseless attenuation using an optical parametric amplifier

    Science.gov (United States)

    Brewster, R. A.; Nodurft, I. C.; Pittman, T. B.; Franson, J. D.

    2017-10-01

    The process of heralded noiseless amplification, and the inverse process of heralded noiseless attenuation, have potential applications in the context of quantum communications. Although several different physical implementations of heralded noiseless amplifiers have now been demonstrated, the research on heralded noiseless attenuators has been largely confined to a beam-splitter based approach. Here we show that an optical parametric amplifier (OPA), combined with appropriate heralding, can also serve as a heralded noiseless attenuator. The counterintuitive use of an optical amplifier as an attenuator is only possible due to the probabilistic nature of the device.

  14. Attenuation corrected SPECT using transmission measurements

    International Nuclear Information System (INIS)

    Ziegler, S.I.; Ficaro, E.P.; Boening, G.; Schwaiger, M.

    1996-01-01

    Modern SPECT instrumentation allows attenuation correction in cardiac scans by using transmission measurements. Simultaneous transmission and emission measurements are feasible with different geometries in multihead SPECT systems and are already commercially available. The selection of the transmission nuclide affects the quality of data, depending on the emission nuclide used. Iterative reconstruction methods have to be implemented to get accurate results in the case of heterogeneous attenuation distributions. Methodological aspects concerning simultaneous scatter and attenuation correction have to be studied in future. The clinical significance of routine attenuation correction measurements for myocardial perfusion has to be shown in a large patient population. (orig.) [de

  15. An Improved Brome mosaic virus Silencing Vector: Greater Insert Stability and More Extensive VIGS1[OPEN

    Science.gov (United States)

    2018-01-01

    Virus-induced gene silencing (VIGS) is used extensively for gene function studies in plants. VIGS is inexpensive and rapid compared with silencing conducted through stable transformation, but many virus-silencing vectors, especially in grasses, induce only transient silencing phenotypes. A major reason for transient phenotypes is the instability of the foreign gene fragment (insert) in the vector during VIGS. Here, we report the development of a Brome mosaic virus (BMV)-based vector that better maintains inserts through modification of the original BMV vector RNA sequence. Modification of the BMV RNA3 sequence yielded a vector, BMVCP5, that better maintained phytoene desaturase and heat shock protein70-1 (HSP70-1) inserts in Nicotiana benthamiana and maize (Zea mays). Longer maintenance of inserts was correlated with greater target gene silencing and more extensive visible silencing phenotypes displaying greater tissue penetration and involving more leaves. The modified vector accumulated similarly to the original vector in N. benthamiana after agroinfiltration, thus maintaining a high titer of virus in this intermediate host used to produce virus inoculum for grass hosts. For HSP70, silencing one family member led to a large increase in the expression of another family member, an increase likely related to the target gene knockdown and not a general effect of virus infection. The cause of the increased insert stability in the modified vector is discussed in relationship to its recombination and accumulation potential. The modified vector will improve functional genomic studies in grasses, and the conceptual methods used to improve the vector may be applied to other VIGS vectors. PMID:29127260

  16. The impact of organizational culture on employees’ organizational silence In Shiraz University of Medical Sciences

    Directory of Open Access Journals (Sweden)

    Ebrahim Parcham

    2017-01-01

    Full Text Available Introduction: Organizational Culture is one of the most important factors that can change the climate of silence. The main aim of this research was to investigate the influence of organizational culture on employees’ organizational silence in Shiraz University of Medical Sciences. Method: This research was a descriptive-correlation one. The target population was chosen from 1900 staff of the University of Medical sciences and Health Care headquarter in Shiraz. Thus 311 employees were selected using the Krejcie and Morgan sampling table. The instrument used in this research was Denison (2006 organizational culture questionnaire and Dimitris Buratas and Maria Vacula (2007 organizational culture. Cornbrash’s alpha method was used to calculate the reliability. The Item analysis and expert consensus were applied to calculate the validity of instruments. All gathered data analyzed with PLS software. Results: The results showed that the four dimensions of organizational culture include organizational involvement, organizational adaptability, organizational concistency and organizational mission was moderate and the mean scores obtained for each factor were 2.85, 2.82, 2.94 and 2.93 respectively. Structural equation model showed Organizational culture has a significant positive impact on organizational silence (β=0.68; P<.001. Conclusion: Based on the results and impact of organizational culture on organizational silence that is positive and significant; The organization further efforts to strengthen various aspects of organizational culture, especially the employees’ involvement in decision making; Employees can better express their opinions and thus reduced their organizational silence. In other words strengthening corporate culture is combined with the reduction of organizational silence. Medical organizations can establish appropriate reward system for creative ideas and suggestions to encourage people express their ideas As a result, reduced

  17. An ImprovedBrome mosaic virusSilencing Vector: Greater Insert Stability and More Extensive VIGS.

    Science.gov (United States)

    Ding, Xin Shun; Mannas, Stephen W; Bishop, Bethany A; Rao, Xiaolan; Lecoultre, Mitchell; Kwon, Soonil; Nelson, Richard S

    2018-01-01

    Virus-induced gene silencing (VIGS) is used extensively for gene function studies in plants. VIGS is inexpensive and rapid compared with silencing conducted through stable transformation, but many virus-silencing vectors, especially in grasses, induce only transient silencing phenotypes. A major reason for transient phenotypes is the instability of the foreign gene fragment (insert) in the vector during VIGS. Here, we report the development of a Brome mosaic virus (BMV)-based vector that better maintains inserts through modification of the original BMV vector RNA sequence. Modification of the BMV RNA3 sequence yielded a vector, BMVCP5, that better maintained phytoene desaturase and heat shock protein70-1 ( HSP70-1 ) inserts in Nicotiana benthamiana and maize ( Zea mays ). Longer maintenance of inserts was correlated with greater target gene silencing and more extensive visible silencing phenotypes displaying greater tissue penetration and involving more leaves. The modified vector accumulated similarly to the original vector in N. benthamiana after agroinfiltration, thus maintaining a high titer of virus in this intermediate host used to produce virus inoculum for grass hosts. For HSP70 , silencing one family member led to a large increase in the expression of another family member, an increase likely related to the target gene knockdown and not a general effect of virus infection. The cause of the increased insert stability in the modified vector is discussed in relationship to its recombination and accumulation potential. The modified vector will improve functional genomic studies in grasses, and the conceptual methods used to improve the vector may be applied to other VIGS vectors. © 2018 American Society of Plant Biologists. All Rights Reserved.

  18. 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.

  19. On the acoustic performance of rectangular splitter silencers in the presence of mean flow

    Science.gov (United States)

    Kirby, Ray; Amott, Ken; Williams, Paul T.; Duan, Wenbo

    2014-12-01

    Dissipative splitter silencers are often used to reduce the noise emitted in ventilation and gas turbine systems. It is well known that the acoustic performance of a splitter silencer changes under the influence of the convective effects of a mean gas flow and so in this article a theoretical model is developed to include the effects of mean flow. The theoretical model is based on a hybrid finite element method which enables the inclusion of bull nose fairings and a perforated screen separating the mean gas flow from a bulk reacting porous material. Predictions are compared against experimental measurements obtained both with and without mean flow. Good agreement between prediction and measurement is generally observed in the absence of mean flow, although it is seen that for silencers with a low percentage open area the silencer insertion loss is over predicted at higher frequencies. When mean flow is present, problems with the experimental methodology are observed at relatively modest mean flow velocities, and so comparison between prediction and experiment is limited to relatively low face velocities. However, experiment and theory both show that the insertion loss reduces at low frequencies when mean flow is in the direction of sound propagation, and at high frequencies the influence of mean flow is generally much smaller. Following additional theoretical investigations it is concluded that the influence of mean flow on splitter silencer performance should be accounted for at low frequencies when silencer airway velocities are greater than about 20 m/s; however, at higher frequencies one may generally neglect the effect of mean flow, even at higher velocities. Predictions obtained using the hybrid method are also compared to a simplified point collocation approach and it is demonstrated that the computationally efficient point collocation method may be used to investigate the effects of mean flow in a splitter silencer without loss of accuracy.

  20. Specific tandem repeats are sufficient for paramutation-induced trans-generational silencing.

    Directory of Open Access Journals (Sweden)

    Christiane L Belele

    Full Text Available Paramutation is a well-studied epigenetic phenomenon in which trans communication between two different alleles leads to meiotically heritable transcriptional silencing of one of the alleles. Paramutation at the b1 locus involves RNA-mediated transcriptional silencing and requires specific tandem repeats that generate siRNAs. This study addressed three important questions: 1 are the tandem repeats sufficient for paramutation, 2 do they need to be in an allelic position to mediate paramutation, and 3 is there an association between the ability to mediate paramutation and repeat DNA methylation levels? Paramutation was achieved using multiple transgenes containing the b1 tandem repeats, including events with tandem repeats of only one half of the repeat unit (413 bp, demonstrating that these sequences are sufficient for paramutation and an allelic position is not required for the repeats to communicate. Furthermore, the transgenic tandem repeats increased the expression of a reporter gene in maize, demonstrating the repeats contain transcriptional regulatory sequences. Transgene-mediated paramutation required the mediator of paramutation1 gene, which is necessary for endogenous paramutation, suggesting endogenous and transgene-mediated paramutation both require an RNA-mediated transcriptional silencing pathway. While all tested repeat transgenes produced small interfering RNAs (siRNAs, not all transgenes induced paramutation suggesting that, as with endogenous alleles, siRNA production is not sufficient for paramutation. The repeat transgene-induced silencing was less efficiently transmitted than silencing induced by the repeats of endogenous b1 alleles, which is always 100% efficient. The variability in the strength of the repeat transgene-induced silencing enabled testing whether the extent of DNA methylation within the repeats correlated with differences in efficiency of paramutation. Transgene-induced paramutation does not require extensive

  1. Development of RNA Interference Trigger-Mediated Gene Silencing in Entamoeba invadens.

    Science.gov (United States)

    Suresh, Susmitha; Ehrenkaufer, Gretchen; Zhang, Hanbang; Singh, Upinder

    2016-04-01

    Entamoeba histolytica, a protozoan parasite, is an important human pathogen and a leading parasitic cause of death. The organism has two life cycle stages, trophozoites, which are responsible for tissue invasion, and cysts, which are involved in pathogen transmission. Entamoeba invadens is the model system to study Entamoeba developmental biology, as high-grade regulated encystation and excystation are readily achievable. However, the lack of gene-silencing tools in E. invadens has limited the molecular studies that can be performed. Using the endogenous RNA interference (RNAi) pathway in Entamoeba, we developed an RNAi-based trigger gene-silencing approach inE. invadens We demonstrate that a gene's coding region that has abundant antisense small RNAs (sRNAs) can trigger silencing of a gene that is fused to it. The trigger fusion leads to the generation of abundant antisense sRNAs that map to the target gene, with silencing occurring independently of trigger location at the 5' or 3' end of a gene. Gene silencing is stably maintained during development, including encystation and excystation. We have used this approach to successfully silence two E. invadens genes: a putative rhomboid protease gene and a SHAQKY family Myb gene. The Myb gene is upregulated during oxidative stress and development, and its downregulation led, as predicted, to decreased viability under oxidative stress and decreased cyst formation. Thus, the RNAi trigger silencing method can be used to successfully investigate the molecular functions of genes inE. invadens Dissection of the molecular basis of Entamoeba stage conversion is now possible, representing an important technical advance for the system. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  2. The Luteovirus P4 Movement Protein Is a Suppressor of Systemic RNA Silencing

    Directory of Open Access Journals (Sweden)

    Adriana F. Fusaro

    2017-10-01

    Full Text Available The plant viral family Luteoviridae is divided into three genera: Luteovirus, Polerovirus and Enamovirus. Without assistance from another virus, members of the family are confined to the cells of the host plant’s vascular system. The first open reading frame (ORF of poleroviruses and enamoviruses encodes P0 proteins which act as silencing suppressor proteins (VSRs against the plant’s viral defense-mediating RNA silencing machinery. Luteoviruses, such as barley yellow dwarf virus-PAV (BYDV-PAV, however, have no P0 to carry out the VSR role, so we investigated whether other proteins or RNAs encoded by BYDV-PAV confer protection against the plant’s silencing machinery. Deep-sequencing of small RNAs from plants infected with BYDV-PAV revealed that the virus is subjected to RNA silencing in the phloem tissues and there was no evidence of protection afforded by a possible decoy effect of the highly abundant subgenomic RNA3. However, analysis of VSR activity among the BYDV-PAV ORFs revealed systemic silencing suppression by the P4 movement protein, and a similar, but weaker, activity by P6. The closely related BYDV-PAS P4, but not the polerovirus potato leafroll virus P4, also displayed systemic VSR activity. Both luteovirus and the polerovirus P4 proteins also showed transient, weak local silencing suppression. This suggests that systemic silencing suppression is the principal mechanism by which the luteoviruses BYDV-PAV and BYDV-PAS minimize the effects of the plant’s anti-viral defense.

  3. Harnessing endogenous miRNAs to control virus tissue tropism as a strategy for developing attenuated virus vaccines.

    Science.gov (United States)

    Barnes, Dwight; Kunitomi, Mark; Vignuzzi, Marco; Saksela, Kalle; Andino, Raul

    2008-09-11

    Live attenuated vaccines remain the safest, most cost-effective intervention against viral infections. Because live vaccine strains are generated empirically and the basis for attenuation is usually ill defined, many important viruses lack an efficient live vaccine. Here, we present a general strategy for the rational design of safe and effective live vaccines that harnesses the microRNA-based gene-silencing machinery to control viral replication. Using poliovirus as a model, we demonstrate that insertion of small miRNA homology sequences into a viral genome can restrict its tissue tropism, thereby preventing pathogenicity and yielding an attenuated viral strain. Poliovirus strains engineered to become targets of neuronal-specific miRNAs lost their ability to replicate in the central nervous system, leading to significant attenuation of neurovirulence in infected animals. Importantly, these viruses retained the ability to replicate in nonneuronal tissues. As a result, these engineered miRNA-regulated viruses elicited strong protective immunity in mice without producing disease.

  4. Harnessing endogenous miRNAs to control virus tissue tropism as a strategy for developing attenuated virus vaccines

    Science.gov (United States)

    Barnes, Dwight; Kunitomi, Mark; Vignuzzi, Marco; Saksela, Kalle; Andino, Raul

    2008-01-01

    Live, attenuated vaccines remain the safest, most cost-effective intervention against viral infections. Because live vaccine strains are generated empirically and the basis for attenuation is usually ill defined, many important viruses lack an efficient live vaccine. Here, we present a general strategy for the rational design of safe and effective live vaccines that harnesses the microRNA-based gene silencing machinery to control viral replication. Using poliovirus as a model, we demonstrate that insertion of small miRNA homology sequences into a viral genome can restrict its tissue tropism, thereby preventing pathogenicity and yielding an attenuated viral strain. Poliovirus strains engineered to become targets of neuronal-specific miRNAs lost their ability to replicate in the central nervous system, leading to significant attenuation of neurovirulence in infected animals. Importantly, these viruses retained the ability to replicate in non-neuronal tissues. As a result, these engineered miRNA-regulated viruses elicited strong protective immunity in mice without producing disease. PMID:18779050

  5. C. elegans RNA-dependent RNA polymerases rrf-1 and ego-1 silence Drosophila transgenes by differing mechanisms.

    Science.gov (United States)

    Duan, Guowen; Saint, Robert B; Helliwell, Chris A; Behm, Carolyn A; Wang, Ming-Bo; Waterhouse, Peter M; Gordon, Karl H J

    2013-04-01

    Drosophila possesses the core gene silencing machinery but, like all insects, lacks the canonical RNA-dependent RNA polymerases (RdRps) that in C. elegans either trigger or enhance two major small RNA-dependent gene silencing pathways. Introduction of two different nematode RdRps into Drosophila showed them to be functional, resulting in differing silencing activities. While RRF-1 enhanced transitive dsRNA-dependent silencing, EGO-1 triggered dsRNA-independent silencing, specifically of transgenes. The strain w; da-Gal4; UAST-ego-1, constitutively expressing ego-1, is capable of silencing transgene including dsRNA hairpin upon a single cross, which created a powerful tool for research in Drosophila. In C. elegans, EGO-1 is involved in transcriptional gene silencing (TGS) of chromosome regions that are unpaired during meiosis. There was no opportunity for meiotic interactions involving EGO-1 in Drosophila that would explain the observed transgene silencing. Transgene DNA is, however, unpaired during the pairing of chromosomes in embryonic mitosis that is an unusual characteristic of Diptera, suggesting that in Drosophila, EGO-1 triggers transcriptional silencing of unpaired DNA during embryonic mitosis.

  6. 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.

  7. 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.

  8. Precision Model for Microwave Rotary Vane Attenuator

    DEFF Research Database (Denmark)

    Guldbrandsen, Tom

    1979-01-01

    A model for a rotary vane attenuator is developed to describe the attenuator reflection and transmission coefficients in detail. All the parameters of the model can be measured in situ, i.e., without diassembling any part. The tranmission errors caused by internal reflections are calculated from ...

  9. Vertical diffuse attenuation coefficient (Kd) based optical ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    mary production and diffuse attenuation coeffi- cient (Austin 1981; Sathyendranath et al 2000). The Indian IRS-P3 ... oceanic and coastal production of phytoplank- ton (Tyler 1975; Pennock and Sharp 1986). As a result basic ... cient to the plant pigment content. The term dif- fuse attenuation coefficient, most commonly used.

  10. Nicotinamide clearance by Pnc1 directly regulates Sir2-mediated silencing and longevity.

    Science.gov (United States)

    Gallo, Christopher M; Smith, Daniel L; Smith, Jeffrey S

    2004-02-01

    The Saccharomyces cerevisiae Sir2 protein is an NAD(+)-dependent histone deacetylase (HDAC) that functions in transcriptional silencing and longevity. The NAD(+) salvage pathway protein, Npt1, regulates Sir2-mediated processes by maintaining a sufficiently high intracellular NAD(+) concentration. However, another NAD(+) salvage pathway component, Pnc1, modulates silencing independently of the NAD(+) concentration. Nicotinamide (NAM) is a by-product of the Sir2 deacetylase reaction and is a natural Sir2 inhibitor. Pnc1 is a nicotinamidase that converts NAM to nicotinic acid. Here we show that recombinant Pnc1 stimulates Sir2 HDAC activity in vitro by preventing the accumulation of NAM produced by Sir2. In vivo, telomeric, rDNA, and HM silencing are differentially sensitive to inhibition by NAM. Furthermore, PNC1 overexpression suppresses the inhibitory effect of exogenously added NAM on silencing, life span, and Hst1-mediated transcriptional repression. Finally, we show that stress suppresses the inhibitory effect of NAM through the induction of PNC1 expression. Pnc1, therefore, positively regulates Sir2-mediated silencing and longevity by preventing the accumulation of intracellular NAM during times of stress.

  11. [Silence pact from the perspective of caretakers of palliative care patients].

    Science.gov (United States)

    Cejudo López, Ángela; López López, Begoña; Duarte Rodríguez, Miguel; Crespo Serván, María Pilar; Coronado Illescas, Concepción; de la Fuente Rodríguez, Carlota

    2015-01-01

    To determine why terminally-ill patients, family caregivers and health care providers make a pact of silence about the terminal status of the patient, and to identify the attitudes, experiences and opinions of family caregivers concerning the conspiracy of silence in palliative care. A qualitative phenomenological study based on an interpretive analysis, conducted in Primary Health Care, Seville, Spain. Study dimensions: knowledge of the diagnosis and prognosis of the condition; disclosure of information; reaction to information received, feelings and approach to death; information disclosed to the patient and reasons behind partial disclosure; communication between patients, families, and health care providers. Family caregivers of patients on palliative care suspicious about a pact of silence. Family caregivers hamper professional-patient communication; use of deceit to conceal the truth; suspicion that the patient knows the truth; the clinician conceals the truth; paternalist attitudes; feelings of sadness, grief, resignation, acceptance of the disease. The pact of silence has negative effects on coping with death, quality of life in the last days of life, and mourning. Communication between patients, health care providers, and families should be improved to prevent the pact of silence, and help patients cope with death. Copyright © 2015 Elsevier España, S.L.U. All rights reserved.

  12. Inheritable Silencing of Endogenous Genes by Hit-and-Run Targeted Epigenetic Editing.

    Science.gov (United States)

    Amabile, Angelo; Migliara, Alessandro; Capasso, Paola; Biffi, Mauro; Cittaro, Davide; Naldini, Luigi; Lombardo, Angelo

    2016-09-22

    Gene silencing is instrumental to interrogate gene function and holds promise for therapeutic applications. Here, we repurpose the endogenous retroviruses' silencing machinery of embryonic stem cells to stably silence three highly expressed genes in somatic cells by epigenetics. This was achieved by transiently expressing combinations of engineered transcriptional repressors that bind to and synergize at the target locus to instruct repressive histone marks and de novo DNA methylation, thus ensuring long-term memory of the repressive epigenetic state. Silencing was highly specific, as shown by genome-wide analyses, sharply confined to the targeted locus without spreading to nearby genes, resistant to activation induced by cytokine stimulation, and relieved only by targeted DNA demethylation. We demonstrate the portability of this technology by multiplex gene silencing, adopting different DNA binding platforms and interrogating thousands of genomic loci in different cell types, including primary T lymphocytes. Targeted epigenome editing might have broad application in research and medicine. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  13. Transcriptionally Silenced Transgenes in Maize Are Activated by Three Mutations Defective in Paramutation

    Science.gov (United States)

    McGinnis, Karen M.; Springer, Catherine; Lin, Yan; Carey, Charles C.; Chandler, Vicki

    2006-01-01

    Plants with mutations in one of three maize genes, mop1, rmr1, and rmr2, are defective in paramutation, an allele-specific interaction that leads to meiotically heritable chromatin changes. Experiments reported here demonstrate that these genes are required to maintain the transcriptional silencing of two different transgenes, suggesting that paramutation and transcriptional silencing of transgenes share mechanisms. We hypothesize that the transgenes are silenced through an RNA-directed chromatin mechanism, because mop1 encodes an RNA-dependent RNA polymerase. In all the mutants, DNA methylation was reduced in the active transgenes relative to the silent transgenes at all of the CNG sites monitored within the transgene promoter. However, asymmetrical methylation persisted at one site within the reactivated transgene in the rmr1-1 mutant. With that one mutant, rmr1-1, the transgene was efficiently resilenced upon outcrossing to reintroduce the wild-type protein. In contrast, with the mop1-1 and rmr2-1 mutants, the transgene remained active in a subset of progeny even after the wild-type proteins were reintroduced by outcrossing. Interestingly, this immunity to silencing increased as the generations progressed, consistent with a heritable chromatin state being formed at the transgene in plants carrying the mop1-1 and rmr2-1 mutations that becomes more resistant to silencing in subsequent generations. PMID:16702420

  14. Identification of Novel Fibrosis Modifiers by In Vivo siRNA Silencing

    Directory of Open Access Journals (Sweden)

    Elisabeth H. Vollmann

    2017-06-01

    Full Text Available Fibrotic diseases contribute to 45% of deaths in the industrialized world, and therefore a better understanding of the pathophysiological mechanisms underlying tissue fibrosis is sorely needed. We aimed to identify novel modifiers of tissue fibrosis expressed by myofibroblasts and their progenitors in their disease microenvironment through RNA silencing in vivo. We leveraged novel biology, targeting genes upregulated during liver and kidney fibrosis in this cell lineage, and employed small interfering RNA (siRNA-formulated lipid nanoparticles technology to silence these genes in carbon-tetrachloride-induced liver fibrosis in mice. We identified five genes, Egr2, Atp1a2, Fkbp10, Fstl1, and Has2, which modified fibrogenesis based on their silencing, resulting in reduced Col1a1 mRNA levels and collagen accumulation in the liver. These genes fell into different groups based on the effects of their silencing on a transcriptional mini-array and histological outcomes. Silencing of Egr2 had the broadest effects in vivo and also reduced fibrogenic gene expression in a human fibroblast cell line. Prior to our study, Egr2, Atp1a2, and Fkbp10 had not been functionally validated in fibrosis in vivo. Thus, our results provide a major advance over the existing knowledge of fibrogenic pathways. Our study is the first example of a targeted siRNA assay to identify novel fibrosis modifiers in vivo.

  15. Lack of sex chromosome specific meiotic silencing in platypus reveals origin of MSCI in therian mammals.

    Science.gov (United States)

    Daish, Tasman J; Casey, Aaron E; Grutzner, Frank

    2015-12-10

    In therian mammals heteromorphic sex chromosomes are subject to meiotic sex chromosome inactivation (MSCI) during meiotic prophase I while the autosomes maintain transcriptional activity. The evolution of this sex chromosome silencing is thought to result in retroposition of genes required in spermatogenesis from the sex chromosomes to autosomes. In birds sex chromosome specific silencing appears to be absent and global transcriptional reductions occur through pachytene and sex chromosome-derived autosomal retrogenes are lacking. Egg laying monotremes are the most basal mammalian lineage, feature a complex and highly differentiated XY sex chromosome system with homology to the avian sex chromosomes, and also lack autosomal retrogenes. In order to delineate the point of origin of sex chromosome specific silencing in mammals we investigated whether MSCI exists in platypus. Our results show that platypus sex chromosomes display only partial or transient colocalisation with a repressive histone variant linked to therian sex chromosome silencing and surprisingly lack a hallmark MSCI epigenetic signature present in other mammals. Remarkably, platypus instead feature an avian like period of general low level transcription through prophase I with the sex chromosomes and the future mammalian X maintaining association with a nucleolus-like structure. Our work demonstrates for the first time that in mammals meiotic silencing of sex chromosomes evolved after the divergence of monotremes presumably as a result of the differentiation of the therian XY sex chromosomes. We provide a novel evolutionary scenario on how the future therian X chromosome commenced the trajectory toward MSCI.

  16. A conversation analysis of the function of silence in writing conferences

    Directory of Open Access Journals (Sweden)

    Milad Mirzaee

    2016-07-01

    Full Text Available One of the recent issues in English as a Second/Foreign Language (ESL/EFL writing instruction has been the quest for a more effective way to give feedback to L2 learners’ writing drafts. Although teacher- learner writing conferences have been increasingly used for providing ample opportunity for negotiating revisions, relatively little attention has been given to actual teacher-learner conversation. Drawing on sociocultural theory, which holds that all cognitive developments are results of ‘social interactions’, and drawing on conversation analysis as an analytical tool, this study attempts to explore the different functions of ‘silence’ in writing conferences during teacher-learner conversation. The data comes from transcripts of six 1-hour writing conferences video-recorded in a graduate program with 7 candidates in Iran. During the writing conferences, learners’ drafts were discussed. Findings of the study demonstrated that teacher’s silence can play a key role in the management of turns in writing conferences, thereby providing the parties with various opportunities for accomplishing intersubjectivity: the teacher used silence to rethink the information provided during writing conferences, and the learner exploited silence to revise the writing draft. The current study, reporting a range of functions of silence in writing conferences, offers an extension to the existing literature and draws language teachers’, specifically writing instructors’, attention to different functions of silence in writing conferences.

  17. Breaking an epigenetic chromatin switch: curious features of hysteresis in Saccharomyces cerevisiae telomeric silencing.

    Directory of Open Access Journals (Sweden)

    Vijayalakshmi H Nagaraj

    Full Text Available In addition to gene network switches, local epigenetic modifications to DNA and histones play an important role in all-or-none cellular decision-making. Here, we study the dynamical design of a well-characterized epigenetic chromatin switch: the yeast SIR system, in order to understand the origin of the stability of epigenetic states. We study hysteresis in this system by perturbing it with a histone deacetylase inhibitor. We find that SIR silencing has many characteristics of a non-linear bistable system, as observed in conventional genetic switches, which are based on activities of a few promoters affecting each other through the abundance of their gene products. Quite remarkably, our experiments in yeast telomeric silencing show a very distinctive pattern when it comes to the transition from bistability to monostability. In particular, the loss of the stable silenced state, upon increasing the inhibitor concentration, does not seem to show the expected saddle node behavior, instead looking like a supercritical pitchfork bifurcation. In other words, the 'off' state merges with the 'on' state at a threshold concentration leading to a single state, as opposed to the two states remaining distinct up to the threshold and exhibiting a discontinuous jump from the 'off' to the 'on' state. We argue that this is an inevitable consequence of silenced and active regions coexisting with dynamic domain boundaries. The experimental observations in our study therefore have broad implications for the understanding of chromatin silencing in yeast and beyond.

  18. Potential of Metal Fibre Felts as Passive Absorbers in Absorption Silencers

    Directory of Open Access Journals (Sweden)

    Björn Hinze

    2013-03-01

    Full Text Available The growing noise exposure of residents, due to a rising number of flights, causes significant impacts on physical health. Therefore it is necessary to reduce the noise emission of aircrafts. During take-off, the noise generated by the jet engines is dominating. One way to lower the noise emission of jet engines is to build an absorption silencer by using porous liners. Because of the high thermic and corrosive attacks as well as high fatigue loads, conventional absorbers cannot be used. A promising material is sintered metal fibre felts. This study investigates the suitability of metal fibre felts for the use as absorption material in silencers. The influences of pore morphology, absorption coefficient, determined with perpendicular sound incidence, as well as geometric parameters of the silencer to the damping are identified. To characterise the material, the parameters fibre diameter, porosity and thickness are determined using three-dimensional computer tomography images. The damping potential of absorption silencers is measured using an impedance tube, which was modified for transmission measurements. The essential parameter to describe the acoustic characteristics of porous materials is the flow resistivity. It depends on the size, shape and number of open pores in the material. Finally a connection between pore morphology, flow resistivity of the metal fibre felts and damping potential of the absorption silencer is given.

  19. Disulfide bond-conjugated dual PEGylated siRNAs for prolonged multiple gene silencing.

    Science.gov (United States)

    Liao, Zi-Xian; Hsiao, Chun-Wen; Ho, Yi-Cheng; Chen, Hsin-Lung; Sung, Hsing-Wen

    2013-09-01

    Many human diseases carry at least two independent gene mutations, further exacerbating clinical disorders. In this work, disulfide bond-conjugated dual PEGylated siRNAs were synthesized, capable of specifically targeting and silencing two genes simultaneously. To achieve efficient delivery, the conjugated siRNAs were formulated with the cationic chitosan together with an anionic polymer, poly(γ-glutamic acid) (γPGA), to form a ternary complex. Experimental results indicate that the incorporated γPGA could significantly enhance their intracellular delivery efficiency, allowing for reduction of the disulfide bond-conjugated PEGylated siRNAs delivered to the PEGylated siRNAs in the reductive cytoplasmic environment. The PEGylated siRNAs could more significantly increase their enzymatic tolerability, effectively silence multiple genes, and prolong the duration of their gene silencing capability than the unmodified siRNAs could. Silencing of different genes simultaneously significantly contributes to the efforts to treat multiple gene disorders, and prolonged duration of gene silencing can reduce the need for frequent administrations. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Klotho gene silencing promotes pathology in the mdx mouse model of Duchenne muscular dystrophy

    Science.gov (United States)

    Wehling-Henricks, Michelle; Li, Zhenzhi; Lindsey, Catherine; Wang, Ying; Welc, Steven S.; Ramos, Julian N.; Khanlou, Négar; Kuro-o, Makoto; Tidball, James G.

    2016-01-01

    Duchenne muscular dystrophy (DMD) is a lethal muscle disease involving progressive loss of muscle regenerative capacity and increased fibrosis. We tested whether epigenetic silencing of the klotho gene occurs in the mdx mouse model of DMD and whether klotho silencing is an important feature of the disease. Our findings show that klotho undergoes muscle-specific silencing at the acute onset of mdx pathology. Klotho experiences increased methylation of CpG sites in its promoter region, which is associated with gene silencing, and increases in a repressive histone mark, H3K9me2. Expression of a klotho transgene in mdx mice restored their longevity, reduced muscle wasting, improved function and greatly increased the pool of muscle-resident stem cells required for regeneration. Reductions of fibrosis in late, progressive stages of the mdx pathology achieved by transgene expression were paralleled by reduced expression of Wnt target genes (axin-2), transforming growth factor-beta (TGF-β1) and collagens types 1 and 3, indicating that Klotho inhibition of the profibrotic Wnt/TGFβ axis underlies its anti-fibrotic effect in aging, dystrophic muscle. Thus, epigenetic silencing of klotho during muscular dystrophy contributes substantially to lost regenerative capacity and increased fibrosis of dystrophic muscle during late progressive stages of the disease. PMID:27154199

  1. Ultrasound fields in an attenuating medium

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt; Gandhi,, D; O'Brien,, W.D., Jr.

    1993-01-01

    of the rectangles and sums all contributions to arrive at the spatial impulse response for the aperture and field point. This approach makes it possible to model all transducer apertures, and the program can readily calculate the emitted, pulse-echo and continuous wave field. Attenuation is included by splitting...... it into a frequency dependent part and frequency independent part. The latter results in an attenuation factor that is multiplied onto the responses from the individual elements, and the frequency dependent part is handled by attenuating the basic one-dimensional pulse. The influence on ultrasound fields from......Ultrasound fields propagating in tissue will undergo changes in shape not only due to diffraction, but also due to the frequency dependent attenuation. Linear fields can be fairly well predicted for a non-attenuating medium like water by using the Tupholme-Stepanishen method for calculating...

  2. Something Blossoms in Between: Silence-Phenomena as a Bordering Notions in Psychology.

    Science.gov (United States)

    Lehmann Oliveros, Olga V

    2016-03-01

    Mysterious yet unavoidable, silence-phenomena appear to us in inherent ambiguity. In its plurality of meanings, phenomena related to silence are often perceived as overwhelming because they transcend the communicative capacity of language making it a challenge for cultural psychology to understand its involvement in our processes of making sense of experience and existence. Human growth and development involve processes where presence, void and content, voice, sound and noise, motion, transition and stillness, have dialectic interactions. In this article I discuss silence-phenomena as a bordering notion in terms of its discursive quality, the silent quality of speech, and the awareness of the ineffable. In addition, I highlight the possible implications of such notion in the understanding of affect from the perspective of Semiotic Cultural Psychology. I also emphasize the importance of considering psychological borders as multi-dimensional, taking the phenomenological experience of temporality as an illustration, which is also related to high emotional involvement of attention.

  3. How abusive supervisors influence employees' voice and silence: the effects of interactional justice and organizational attribution.

    Science.gov (United States)

    Wang, Rong; Jiang, Jiang

    2015-01-01

    In this research we investigated the influence of abusive supervision on employees' prosocial voice and silence, as well as clarified the roles of interactional justice (as a mediator) and organizational attribution (as a moderator). Moreover, we examined a mediated moderating model stipulating that interactional justice mediated the moderating effect of organizational attribution on the focal relationship. A scenario experiment was employed in Study 1, and after analyzing data from 196 employees, we found that abusive supervision influenced employees' prosocial voice and silence via interactional justice. In Study 2, data were collected from 379 employees in two waves separated by 1 week. The results not only replicated the findings of Study 1 but also indicated that organizational attribution buffered the abusive supervision-voice and silence relationship, and that interactional justice mediated this moderating effect.

  4. Virus-Induced Gene Silencing in Maize with a Foxtail mosaic virus Vector.

    Science.gov (United States)

    Mei, Yu; Whitham, Steven A

    2018-01-01

    Virus-induced gene silencing (VIGS) is a powerful technology for rapidly and transiently knocking down the expression of plant genes to study their functions. A VIGS vector for maize derived from Foxtail mosaic virus (FoMV), a positive-sense single-stranded RNA virus, was recently developed. A cloning site created near the 3' end of the FoMV genome enables insertion of 200-400 nucleotide fragments of maize genes targeted for silencing. The recombinant FoMV clones are inoculated into leaves of maize seedlings by biolistic particle delivery, and silencing is typically observed within 2 weeks after inoculation. This chapter provides a protocol for constructing FoMV VIGS clones and inoculating them into maize seedlings.

  5. 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.

  6. V2 from a curtovirus is a suppressor of post-transcriptional gene silencing.

    Science.gov (United States)

    Luna, Ana P; Rodríguez-Negrete, Edgar A; Morilla, Gabriel; Wang, Liping; Lozano-Durán, Rosa; Castillo, Araceli G; Bejarano, Eduardo R

    2017-10-01

    The suppression of gene silencing is a key mechanism for the success of viral infection in plants. DNA viruses from the Geminiviridae family encode several proteins that suppress transcriptional and post-transcriptional gene silencing (TGS/PTGS). In Begomovirus, the most abundant genus of this family, three out of six genome-encoded proteins, namely C2, C4 and V2, have been shown to suppress PTGS, with V2 being the strongest PTGS suppressor in transient assays. Beet curly top virus (BCTV), the model species for the Curtovirus genus, is able to infect the widest range of plants among geminiviruses. In this genus, only one protein, C2/L2, has been described as inhibiting PTGS. We show here that, despite the lack of sequence homology with its begomoviral counterpart, BCTV V2 acts as a potent PTGS suppressor, possibly by impairing the RDR6 (RNA-dependent RNA polymerase 6)/suppressor of gene silencing 3 (SGS3) pathway.

  7. Gold Nanorod-siRNA Induces Efficient In Vivo Gene Silencing in the Rat Hippocampus

    Science.gov (United States)

    Bonoiu, Adela C.; Bergey, Earl J.; Ding, Hong; Hu, Rui; Kumar, Rajiv; Yong, Ken-Tye; Prasad, Paras N.; Mahajan, Supriya; Picchione, Kelly E.; Bhattacharjee, Arin; Ignatowski, Tracey A.

    2011-01-01

    Gold nanorods (GNRs), cellular imaging nanoprobes, have been used for drug delivery therapy to immunologically privileged regions in the brain. We demonstrate that nanoplexes formed by electrostatic binding between negatively charged RNA and positively charged GNRs, silence the expression of the target housekeeping gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) within the CA1 hippocampal region of the rat brain, without showing cytotoxicity. Fluorescence imaging with siRNACy3GAPDH and dark field imaging using plasmonic enhanced scattering from GNRs were used to monitor the distribution of the nanoplexes within different neuronal cell types present in the targeted hippocampal region. Our results show robust nanoplex uptake and slow release of the fluorescent gene silencer with significant impact on suppression of GAPDH gene expression (70% gene silencing, >10 days post-injection). The observed gene knockdown using nanoplexes in targeted regions of the brain opens a new era of drug treatment for neurological disorders. PMID:21718174

  8. Smuggling gold nanoparticles across cell types - A new role for exosomes in gene silencing.

    Science.gov (United States)

    Roma-Rodrigues, Catarina; Pereira, Francisca; Alves de Matos, António P; Fernandes, Marta; Baptista, Pedro V; Fernandes, Alexandra R

    2017-05-01

    Once released to the extracellular space, exosomes enable the transfer of proteins, lipids and RNA between different cells, being able to modulate the recipient cells' phenotypes. Members of the Rab small GTP-binding protein family, such as RAB27A, are responsible for the coordination of several steps in vesicle trafficking, including budding, mobility, docking and fusion. The use of gold nanoparticles (AuNPs) for gene silencing is considered a cutting-edge technology. Here, AuNPs were functionalized with thiolated oligonucleotides anti-RAB27A (AuNP@PEG@anti-RAB27A) for selective silencing of the gene with a consequent decrease of exosomes´ release by MCF-7 and MDA-MB-453 cells. Furthermore, communication between tumor and normal cells was observed both in terms of alterations in c-Myc gene expression and transportation of the AuNPs, mediating gene silencing in secondary cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Long Double-Stranded Multiplex siRNAs for Dual Genes Silencing

    Science.gov (United States)

    Peng, Wei; Chen, Jianxin; Qin, Yinchao; Yang, Zhenjun

    2013-01-01

    Simultaneous suppression of multiple oncogenes is an attractive strategy to treat cancers. Herein we present a series of long double-stranded multiplex small interfering RNAs (multi-siRNAs) that is suitable for dual genes silencing through a sequence-specific RNA interference process without inducing significant immune responses. A gap feature structurally designed in either of the nucleotide strands of the multi-siRNAs was proved to be essential toward silencing target genes and avoiding immune responses. Furthermore, the silencing effect of multi-siRNAs against SURVIVIN and BCL-2 genes was shown to be effective and resulted in up-regulation of caspase-3 related apoptosis and, in turn, inhibition of bladder cancer cell proliferation. Our observation suggested that the rationally designed multi-siRNAs would have great potential for therapeutic siRNA design. PMID:23656495

  10. Use of guanidinopropyl-modified siRNAs to silence gene expression.

    Science.gov (United States)

    Buff, Maximilian C R; Bernhardt, Stefan; Marimani, Musa D; Ely, Abdullah; Engels, Joachim W; Arbuthnot, Patrick

    2015-01-01

    Silencing gene expression by harnessing the RNA interference (RNAi) pathway with short interfering RNAs (siRNAs) has useful analytical and potentially therapeutic application. To augment silencing efficacy of siRNAs, chemical modification has been employed to improve stability, target specificity, and delivery to target tissues. siRNAs incorporating guanidinopropyl (GP) moieties have demonstrated enhanced target gene silencing in cell culture and in vivo models of hepatitis B virus replication. Here we describe the synthesis of GP-modified siRNAs and use of 5' rapid amplification of cDNA ends (5' RACE) to verify an RNAi-mediated mechanism of action of these novel chemically modified siRNAs.

  11. 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.

  12. Gene silencing for epidermal growth factor receptor variant III induces cell-specific cytotoxicity.

    Science.gov (United States)

    Yamoutpour, Farnaz; Bodempudi, Vidya; Park, Shay E; Pan, Weihong; Mauzy, Mary Jean; Kratzke, Robert A; Dudek, Arkadiusz; Potter, David A; Woo, Richard A; O'Rourke, Donald M; Tindall, Donald J; Farassati, Faris

    2008-11-01

    Epidermal growth factor receptor variant III (EGFRvIII) is a constitutively active mutant form of EGFR that is expressed in 40% to 50% of gliomas and several other malignancies. Here, we describe the therapeutic effects of silencing EGFRvIII on glioma cell lines in vitro and in vivo. A small interfering RNA molecule against EGFRvIII was introduced into EGFRvIII-expressing glioma cells (U87Delta) by electroporation resulting in complete inhibition of expression of EGFRvIII as early as 48 h post-treatment. During EGFRvIII silencing, a decrease in the proliferation and invasiveness of U87Delta cells was accompanied by an increase in apoptosis (P < 0.05). Notably, EGFRvIII silencing inhibited the signal transduction machinery downstream of EGFRvIII as evidenced by decreases in the activated levels of Ras and extracellular signal-regulated kinase. A lentivirus capable of expressing anti-EGFRvIII short hairpin RNA was also able to achieve progressive silencing of EGFRvIII in U87Delta cells in addition to inhibiting cell proliferation, invasiveness, and colony formation in a significant manner (P < 0.05). Silencing EGFRvIII in U87Delta cultures with this virus reduced the expression of factors involved in epithelial-mesenchymal transition including N-cadherin, beta-catenin, Snail, Slug, and paxillin but not E-cadherin. The anti-EGFRvIII lentivirus also affected the cell cycle progression of U87Delta cells with a decrease in G(1) and increase in S and G(2) fractions. In an in vivo model, tumor growth was completely inhibited in severe combined immunodeficient mice (n = 10) injected s.c. with U87Delta cells treated with the anti-EGFRvIII lentivirus (P = 0.005). We conclude that gene specific silencing of EGFRvIII is a promising strategy for treating cancers that contain this mutated receptor.

  13. The Impact of Gene Silencing on Horizontal Gene Transfer and Bacterial Evolution.

    Science.gov (United States)

    Navarre, W W

    2016-01-01

    The H-NS family of DNA-binding proteins is the subject of intense study due to its important roles in the regulation of horizontally acquired genes critical for virulence, antibiotic resistance, and metabolism. Xenogeneic silencing proteins, typified by the H-NS protein of Escherichia coli, specifically target and downregulate expression from AT-rich genes by selectively recognizing specific structural features unique to the AT-rich minor groove. In doing so, these proteins facilitate bacterial evolution; enabling these cells to engage in horizontal gene transfer while buffering potential any detrimental fitness consequences that may result from it. Xenogeneic silencing and counter-silencing explain how bacterial cells can evolve effective gene regulatory strategies in the face of rampant gene gain and loss and it has extended our understanding of bacterial gene regulation beyond the classic operon model. Here we review the structures and mechanisms of xenogeneic silencers as well as their impact on bacterial evolution. Several H-NS-like proteins appear to play a role in facilitating gene transfer by other mechanisms including by regulating transposition, conjugation, and participating in the activation of virulence loci like the locus of enterocyte effacement pathogenicity island of pathogenic strains of E. coli. Evidence suggests that the critical determinants that dictate whether an H-NS-like protein will be a silencer or will perform a different function do not lie in the DNA-binding domain but, rather, in the domains that control oligomerization. This suggests that H-NS-like proteins are transcription factors that both recognize and alter the shape of DNA to exert specific effects that include but are not limited to gene silencing. © 2016 Elsevier Ltd All rights reserved.

  14. The effects of sedative music, arousal music, and silence on electrocardiography signals.

    Science.gov (United States)

    Dousty, Mehdy; Daneshvar, Sabalan; Haghjoo, Majid

    2011-01-01

    Research indicates that music can affect heart rate, blood pressure, and skin conductance. Music can stimulate central emotions in the brain and release biochemical materials that change the physiologic state. We sought to compare changes in the electrical function of the heart in response to music. Subjects were asked to listen to 2 types of music, namely, sedative and arousal music, in conjunction with two 30-second periods of complete silence. The experiment was conducted in 4 segments: the first and third parts were silence, and the second and fourth parts were music. First, the response to each type of music was compared with that to the preceding period of silence. Next, the responses to both types of music were compared. Finally, the response to music regardless of the type was compared with that to silence. The amplitude of polarization and depolarization changed in response to different kinds of music. The electrical function of the heart in response to music, irrespective of the music type, differed from that in response to silence. The 2 types of music impacted the electrical function of the heart in different ways: the arousal music influenced T-wave maximum amplitude, whereas no such change was recorded in response to the sedative music. The bandwidth of the polarization and depolarization of the heart rate and R-wave amplitude increased in response to music by comparison with silence. In addition, the heart did not seem to try to synchronize with music. The mean R-wave amplitude in sedative music is higher than the arousal music, so our heart works differently when different types of music are heard. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Organizational Silence Among Nurses: The Impact on Organizational Cynicism and Intention to Leave Work.

    Science.gov (United States)

    Çaylak, Esra; Altuntaş, Serap

    2017-04-01

    In recent years, organizational silence and organizational cynicism, factors that have been shown to inhibit the improvement of organizations, have been highlighted in the health sector. Nearly every aspect of these two issues has been studied. This research was conducted to identify the relationship between the organizational silence, organizational cynicism, and intention to leave work of nurses. This descriptive and correlational study was carried out in August and September 2013 with 323 nurses at a university hospital in Ankara. A questionnaire that includes a personal information form, the Organizational Silence Scale, the Organizational Cynicism Scale, and a question about intention to leave work was used. Ethics committee approval and institutional permissions were obtained. A statistician analyzed the data. The present research found administrative and organizational reasons to be the most important reason why participants remain silent (M = 35.4 ± 13.1), with the tendency not to speak up about ethics and responsibility issues the second most important reason (M = 17.3 ± 6.5). The organizational cynicism of participants is at an intermediate level (M = 36.4 ± 9.6) and may be characterized as cognitive (M = 14.6 ± 4.3). Approximately half of the participants had never considered leaving work. For the participants in this study, organizational silence particularly influences organizational cynicism. The reasons for organizational silence in conjunction with organizational cynicism increase intent to leave work (R = .395, R = .156, p < .001). This study found that the reasons for organizational silence and organizational cynicism influence the intention of nurses to leave work. The reasons that lead nurses to become silent, to experience cynicism, and to leave work in healthcare environments should be identified. Programs and activities to replace negative ideas with positive ideas should be implemented.

  16. Transport and attenuation of radiations

    CERN Document Server

    Nimal, J C

    2003-01-01

    This article treats of the calculation methods used for the dimensioning of the protections against radiations. The method consists in determining for a given point the flux of particles coming from a source at a given time. A strong attenuation (of about some few mu Sv.h sup - sup 1) is in general expected between the source and the areas accessible to the personnel or the public. The calculation has to take into account a huge number of radiation-matter interactions and to solve the integral-differential transport equation which links the particles flux to the source. Several methods exist from the simplified physical model with numerical developments to the more or less precise resolution of the transport equation. These methods allows also the calculation of the uncertainties of equivalent dose rates, heat sources, structure damages using the data covariances (efficient cross-sections, modeling, etc..): 1 - transport equation; 2 - Monte-Carlo method; 3 - semi-numerical methods S sub N; 4 - methods based o...

  17. Beta attenuation transmission system (BATS)

    International Nuclear Information System (INIS)

    Hagan, R.C.; Fullbright, H.J.

    1977-01-01

    The beta attenuation transmission system (BATS) is an automated radiation gauge designed for quantitative measurement of component thickness in explosive detonators. The BATS was designed and built by Group M-1, the Nondestructive Testing Group, of the Los Alamos Scientific Laboratory to measure the areal thickness, in mg/cm 2 , of a cylinder of high explosive (HE) enclosed within a plastic holder. The problem is to determine the density of the HE. A 90 Sr source is collimated by a 0.25 x 1.59-mm slit, and the transmitted beta-particle flux is detected by a plastic scintillator, coupled to a photomultiplier tube. The detonator is transported through the radiation beam by a leadscrew, ballnut, stepping-motor combination. Continuous analog position data are available, derived from the output from a linear-actuated potentiometer attached to the scanner. A linear electrometer amplifies the detected signal, which is then integrated for a preselected time, to obtain the desired statistical accuracy. A microprocessor (μP) is used to control the scanner position and to make the data readings at the assigned positions. The data are stored, and, at the completion of the scan, are processed into the desired format. The final answer is displayed to the operator or output to a peripheral device for permanent record. The characteristics of the radiation source, the collimator, the signal detection and conditioning, and the final results are described in detail. The scanner and the microprocessor control system are briefly outlined

  18. H-NS silences gfp, the green fluorescent protein gene: gfpTCD is a genetically Remastered gfp gene with reduced susceptibility to H-NS-mediated transcription silencing and with enhanced translation.

    Science.gov (United States)

    Corcoran, Colin P; Cameron, Andrew D S; Dorman, Charles J

    2010-09-01

    The bacterial nucleoid-associated protein H-NS, which preferentially targets and silences A+T-rich genes, binds the ubiquitous reporter gene gfp and dramatically reduces local transcription. We have redesigned gfp to reduce H-NS-mediated transcription silencing and simultaneously improve translation in vivo without altering the amino acid sequence of the GFP protein.

  19. Optimized cDNA libraries for virus-induced gene silencing (VIGS using tobacco rattle virus

    Directory of Open Access Journals (Sweden)

    Page Jonathan E

    2008-01-01

    Full Text Available Abstract Background Virus-induced gene silencing (VIGS has emerged as a method for performing rapid loss-of-function experiments in plants. Despite its expanding use, the effect of host gene insert length and other properties on silencing efficiency have not been systematically tested. In this study, we probed the optimal properties of cDNA fragments of the phytoene desaturase (PDS gene for efficient VIGS in Nicotiana benthamiana using tobacco rattle virus (TRV. Results NbPDS inserts of between 192 bp and 1304 bp led to efficient silencing as determined by analysis of leaf chlorophyll a levels. The region of the NbPDS cDNA used for silencing had a small effect on silencing efficiency with 5' and 3' located inserts performing more poorly than those from the middle. Silencing efficiency was reduced by the inclusion of a 24 bp poly(A or poly(G homopolymeric region. We developed a method for constructing cDNA libraries for use as a source of VIGS-ready constructs. Library construction involved the synthesis of cDNA on a solid phase support, digestion with RsaI to yield short cDNA fragments lacking poly(A tails and suppression subtractive hybridization to enrich for differentially expressed transcripts. We constructed two cDNA libraries from methyl-jasmonate treated N. benthamiana roots and obtained 2948 ESTs. Thirty percent of the cDNA inserts were 401–500 bp in length and 99.5% lacked poly(A tails. To test the efficiency of constructs derived from the VIGS-cDNA libraries, we silenced the nicotine biosynthetic enzyme, putrescine N-methyltransferase (PMT, with ten different VIGS-NbPMT constructs ranging from 122 bp to 517 bp. Leaf nicotine levels were reduced by more than 90% in all plants infected with the NbPMT constructs. Conclusion Based on the silencing of NbPDS and NbPMT, we suggest the following design guidelines for constructs in TRV vectors: (1 Insert lengths should be in the range of ~200 bp to ~1300 bp, (2 they should be positioned in

  20. Tat RNA silencing suppressor activity contributes to perturbation of lymphocyte miRNA by HIV-1

    Directory of Open Access Journals (Sweden)

    Yu Lianbo

    2011-05-01

    Full Text Available Abstract Background MicroRNA (miRNA-mediated RNA silencing is integral to virtually every cellular process including cell cycle progression and response to virus infection. The interplay between RNA silencing and HIV-1 is multifaceted, and accumulating evidence posits a strike-counterstrike interface that alters the cellular environment to favor virus replication. For instance, miRNA-mediated RNA silencing of HIV-1 translation is antagonized by HIV-1 Tat RNA silencing suppressor activity. The activity of HIV-1 accessory proteins Vpr/Vif delays cell cycle progression, which is a process prominently modulated by miRNA. The expression profile of cellular miRNA is altered by HIV-1 infection in both cultured cells and clinical samples. The open question stands of what, if any, is the contribution of Tat RNA silencing suppressor activity or Vpr/Vif activity to the perturbation of cellular miRNA by HIV-1. Results Herein, we compared the perturbation of miRNA expression profiles of lymphocytes infected with HIV-1NL4-3 or derivative strains that are deficient in Tat RNA silencing suppressor activity (Tat K51A substitution or ablated of the vpr/vif open reading frames. Microarrays recapitulated the perturbation of the cellular miRNA profile by HIV-1 infection. The miRNA expression trends overlapped ~50% with published microarray results on clinical samples from HIV-1 infected patients. Moreover, the number of miRNA perturbed by HIV-1 was largely similar despite ablation of Tat RSS activity and Vpr/Vif; however, the Tat RSS mutation lessened HIV-1 downregulation of twenty-two miRNAs. Conclusions Our study identified miRNA expression changes attributable to Tat RSS activity in HIV-1NL4-3. The results accomplish a necessary step in the process to understand the interface of HIV-1 with host RNA silencing activity. The overlap in miRNA expression trends observed between HIV-1 infected CEMx174 lymphocytes and primary cells supports the utility of cultured

  1. Silencing of CEMIP suppresses Wnt/β-catenin/Snail signaling transduction and inhibits EMT program of colorectal cancer cells.

    Science.gov (United States)

    Liang, Guodong; Fang, Xuedong; Yang, Yubo; Song, Yan

    2018-01-01

    Cell migration inducing hyaluronan binding protein (CEMIP) is a hyaluronic acid binding protein, the abnormal elevation of which is suggested as a contributor in the carcinogenesis of colorectal cancer (CRC). Cancer cells lose their adhesive properties and acquire an enhanced mobility by undergoing epithelial-mesenchymal transition (EMT). This study is performed to investigate whether and how CEMIP orchestrates the EMT process of CRC cells. To avoid the unexpected off-target effects possibly caused by one single shRNA, two shRNAs targeting different mRNA regions of CEMIP gene were used to knock down the mRNA and protein expression of CEMIP. Our data showed that the proliferation, migration and invasion of two CRC cell lines, HCT116 and SW480 cells, were inhibited by CEMIP shRNA. We here defined EMT as the complete or partial loss of E-cadherin and zona occludens protein 1 (ZO-1) (epithelial markers) and the gain of Vimentin and N-cadherin (mesenchymal markers), and found that the EMT process was attenuated in CEMIP-silenced SW480 cells. Snail, a direct target of β-catenin/T cell factor complex, is known to activate the EMT program during cancer metastasis. CEMIP shRNA was further found to suppress the Wnt/β-catenin/Snail signaling transduction in CRC cells as manifested by the decreased nuclear β-catenin and Snail. Collectively, our work demonstrates that CEMIP contributes to metastatic phenotype of CRC cells in vitro. Copyright © 2017 Elsevier GmbH. All rights reserved.

  2. Silencing β3 Integrin by Targeted ECO/siRNA Nanoparticles Inhibits EMT and Metastasis of Triple Negative Breast Cancer

    Science.gov (United States)

    Mack, Margaret A.; Schiemann, William P.; Lu, Zheng-Rong

    2015-01-01

    Metastatic breast cancer is the second leading cause of cancer-related deaths amongst women. Triple-negative breast cancer (TNBC) is a highly aggressive subcategory of breast cancer and currently lacks well-defined molecular targets for effective targeted therapies. Disease relapse, metastasis, and drug resistance render standard chemotherapy ineffective in the treatment of TNBC. Since previous studies coupled β3 integrin to epithelial-mesenchymal transition (EMT) and metastasis, we exploited β3 integrin as a therapeutic target to treat TNBC by delivering β3 integrin siRNA via lipid ECO-based nanoparticles (ECO/siβ3). Treatment of TNBC cells with ECO/siβ3 was sufficient to effectively silence β3 integrin expression, attenuate TGF-β-mediated EMT and invasion, restore TGF-β-mediated cytostasis, and inhibit 3-dimensional organoid growth. Modification of ECO/siβ3 nanoparticles with an RGD peptide via a PEG spacer enhanced siRNA uptake by post-EMT cells. Intravenous injections of RGD-targeted ECO/siβ3 nanoparticles in vivo alleviated primary tumor burden, and more importantly, significantly inhibited metastasis. Mice bearing orthotopic, TGF-β-pre-stimulated MDA-MB-231 tumors that were treated with RGD-targeted ECO/siβ3 nanoparticles were free of metastases and relapse after primary tumor resection and 4 weeks after release from the treatment, in comparison to untreated mice. Collectively, these results highlight ECO/siβ3 nanoparticles as a promising therapeutic regimen to combat TNBC. PMID:25858145

  3. PGC-1 silencing compounds the perturbation of mitochondrial function caused by mutant SOD1 in skeletal muscle of ALS mouse model

    Directory of Open Access Journals (Sweden)

    Yan eQi

    2015-10-01

    Full Text Available Amyotrophic lateral sclerosis (ALS is a lethal neurodegenerative disease causing death of motor neurons. This study investigated the roles of energy metabolism in the pathogenesis of ALS in the SOD1(G93A transgenic mouse model. Control and SOD1(G93A mice were administered with shcontrol or shPGC-1α in combination with PBS or TZD for 8 weeks. Gene expression was analyzed by quantitative real-time PCR and western blot. ROS and fibrosis were assessed with a colorimetric kit and Sirius staining respectively. Inflammatory cytokines were measured using ELISA kits. The levels of tissue ROS and serum inflammatory cytokines were significantly higher in SOD1(G93A mice compared to control mice, and knocking down PGC-1α drastically increased cytokine levels in both control and SOD1(G93A mice. Muscle fibrosis was much severer in SOD1(G93A mice, and worsened by silencing PGC-1α and attenuate d by TZD. The expression levels of PGC-1α, SOD1, UCP2, and cytochrome C were substantially reduced by shPGC-1α and increased by TZD in muscle of both control and SOD1(G93A mice whereas the level of NF-B was significantly elevated in SOD1(G93A mice, which was further increased by PGC-1α silencing. These data indicated that disruption of energy homeostasis would exacerbate the pathological changes caused by SOD1 mutations to promote the pathogenesis of ALS.

  4. Dual miRNA Targeting Restricts Host Range and Attenuates Neurovirulence of Flaviviruses

    Science.gov (United States)

    Tsetsarkin, Konstantin A.; Liu, Guangping; Kenney, Heather; Bustos-Arriaga, Jose; Hanson, Christopher T.; Whitehead, Stephen S.; Pletnev, Alexander G.

    2015-01-01

    Mosquito-borne flaviviruses are among the most significant arboviral pathogens worldwide. Vaccinations and mosquito population control programs remain the most reliable means for flavivirus disease prevention, and live attenuated viruses remain one of the most attractive flavivirus vaccine platforms. Some live attenuated viruses are capable of infecting principle mosquito vectors, as demonstrated in the laboratory, which in combination with their intrinsic genetic instability could potentially lead to a vaccine virus reversion back to wild-type in nature, followed by introduction and dissemination of potentially dangerous viral strains into new geographic locations. To mitigate this risk we developed a microRNA-targeting approach that selectively restricts replication of flavivirus in the mosquito host. Introduction of sequences complementary to a mosquito-specific mir-184 and mir-275 miRNAs individually or in combination into the 3’NCR and/or ORF region resulted in selective restriction of dengue type 4 virus (DEN4) replication in mosquito cell lines and adult Aedes mosquitos. Moreover a combined targeting of DEN4 genome with mosquito-specific and vertebrate CNS-specific mir-124 miRNA can silence viral replication in two evolutionally distant biological systems: mosquitoes and mouse brains. Thus, this approach can reinforce the safety of newly developed or existing vaccines for use in humans and could provide an additional level of biosafety for laboratories using viruses with altered pathogenic or transmissibility characteristics. PMID:25906260

  5. Attenuation of a phosphorylation-dependent activator by an HDAC-PP1 complex.

    Science.gov (United States)

    Canettieri, Gianluca; Morantte, Ianessa; Guzmán, Ernesto; Asahara, Hiroshi; Herzig, Stephan; Anderson, Scott D; Yates, John R; Montminy, Marc

    2003-03-01

    The second messenger cAMP stimulates transcription with burst-attenuation kinetics that mirror the PKA-dependent phosphorylation and subsequent protein phosphatase 1 (PP1)-mediated dephosphorylation of the cAMP responsive element binding protein (CREB) at Ser133. Phosphorylation of Ser133 promotes recruitment of the co-activator histone acetylase (HAT) paralogs CBP and P300, which in turn stimulate acetylation of promoter-bound histones during the burst phase. Remarkably, histone deacetylase (HDAC) inhibitors seem to potentiate CREB activity by prolonging Ser133 phosphorylation in response to cAMP stimulus, suggesting a potential role for HDAC complexes in silencing CREB activity. Here we show that HDAC1 associates with and blocks Ser133 phosphorylation of CREB during pre-stimulus and attenuation phases of the cAMP response. HDAC1 promotes Ser133 dephosphorylation via a stable interaction with PP1, which we detected in co-immunoprecipitation and co-purification studies. These results illustrate a novel mechanism by which signaling and chromatin-modifying activities act coordinately to repress the activity of a phosphorylation-dependent activator.

  6. Dual miRNA targeting restricts host range and attenuates neurovirulence of flaviviruses.

    Directory of Open Access Journals (Sweden)

    Konstantin A Tsetsarkin

    2015-04-01

    Full Text Available Mosquito-borne flaviviruses are among the most significant arboviral pathogens worldwide. Vaccinations and mosquito population control programs remain the most reliable means for flavivirus disease prevention, and live attenuated viruses remain one of the most attractive flavivirus vaccine platforms. Some live attenuated viruses are capable of infecting principle mosquito vectors, as demonstrated in the laboratory, which in combination with their intrinsic genetic instability could potentially lead to a vaccine virus reversion back to wild-type in nature, followed by introduction and dissemination of potentially dangerous viral strains into new geographic locations. To mitigate this risk we developed a microRNA-targeting approach that selectively restricts replication of flavivirus in the mosquito host. Introduction of sequences complementary to a mosquito-specific mir-184 and mir-275 miRNAs individually or in combination into the 3'NCR and/or ORF region resulted in selective restriction of dengue type 4 virus (DEN4 replication in mosquito cell lines and adult Aedes mosquitos. Moreover a combined targeting of DEN4 genome with mosquito-specific and vertebrate CNS-specific mir-124 miRNA can silence viral replication in two evolutionally distant biological systems: mosquitoes and mouse brains. Thus, this approach can reinforce the safety of newly developed or existing vaccines for use in humans and could provide an additional level of biosafety for laboratories using viruses with altered pathogenic or transmissibility characteristics.

  7. Host-induced gene silencing: a tool for understanding fungal host interaction and for developing novel disease control strategies.

    Science.gov (United States)

    Nunes, Cristiano C; Dean, Ralph A

    2012-06-01

    Recent discoveries regarding small RNAs and the mechanisms of gene silencing are providing new opportunities to explore fungal pathogen-host interactions and potential strategies for novel disease control. Plant pathogenic fungi are a constant and major threat to global food security; they represent the largest group of disease-causing agents on crop plants on the planet. An initial understanding of RNA silencing mechanisms and small RNAs was derived from model fungi. Now, new knowledge with practical implications for RNA silencing is beginning to emerge from the study of plant-fungus interactions. Recent studies have shown that the expression of silencing constructs in plants designed on fungal genes can specifically silence their targets in invading pathogenic fungi, such as Fusarium verticillioides, Blumeria graminis and Puccinia striiformis f.sp. tritici. Here, we highlight the important general aspects of RNA silencing mechanisms and emphasize recent findings from plant pathogenic fungi. Strategies to employ RNA silencing to investigate the basis of fungal pathogenesis are discussed. Finally, we address important aspects for the development of fungal-derived resistance through the expression of silencing constructs in host plants as a powerful strategy to control fungal disease. © 2011 The Authors. Molecular Plant Pathology © 2011 BSPP and Blackwell Publishing Ltd.

  8. The influenza A virus NS1 protein binds small interfering RNAs and suppresses RNA silencing in plants

    NARCIS (Netherlands)

    Bucher, E.C.; Hemmes, J.C.; Haan, de P.; Goldbach, R.W.; Prins, M.W.

    2004-01-01

    RNA silencing comprises a set of sequence-specific RNA degradation pathways that occur in a wide range of eukaryotes, including animals, fungi and plants. A hallmark of RNA silencing is the presence of small interfering RNA molecules (siRNAs). The siRNAs are generated by cleavage of larger

  9. Uudised : Rannap sai raha lõpuks kätte. No Big Silence esitleb uut heliplaati

    Index Scriptorium Estoniae

    2000-01-01

    Pärnus toimunud lühima öö laulukonkursil võitis peaauhinna R. Rannap. Ans. No-Big-Silence on soojendusbändiks 2. juulil Tallinna Lauluväljakul toimuval Iron Maideni kontserdil. Ans. No-Big-Silence esitleb oma uut heliplaati "successful, bitch and beautiful"

  10. Attenuation caused by infrequently updated covariates in survival analysis

    DEFF Research Database (Denmark)

    Andersen, Per Kragh; Liestøl, Knut

    2003-01-01

    Attenuation; Cox regression model; Measurement errors; Survival analysis; Time-dependent covariates......Attenuation; Cox regression model; Measurement errors; Survival analysis; Time-dependent covariates...

  11. Attenuation of the influenza virus by microRNA response element in vivo and protective efficacy against 2009 pandemic H1N1 virus in mice.

    Science.gov (United States)

    Feng, Chunlai; Tan, Mingming; Sun, Wenkui; Shi, Yi; Xing, Zheng

    2015-09-01

    The 2009 influenza pandemics underscored the need for effective vaccines to block the spread of influenza virus infection. Most live attenuated vaccines utilize cold-adapted, temperature-sensitive virus. An alternative to live attenuated virus is presented here, based on microRNA-induced gene silencing. In this study, miR-let-7b target sequences were inserted into the H1N1 genome to engineer a recombinant virus - miRT-H1N1. Female BALB/c mice were vaccinated intranasally with the miRT-H1N1 and challenged with a lethal dose of homologous virus. This miRT-H1N1 virus was attenuated in mice, while it exhibited wild-type characteristics in chicken embryos. Mice vaccinated intranasally with the miRT-H1N1 responded with robust immunity that protected the vaccinated mice from a lethal challenge with the wild-type 2009 pandemic H1N1 virus. These results indicate that the influenza virus containing microRNA response elements (MREs) is attenuated in vivo and can be used to design a live attenuated vaccine. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  12. Analysis of geminivirus AL2 and L2 proteins reveals a novel AL2 silencing suppressor activity.

    Science.gov (United States)

    Jackel, Jamie N; Buchmann, R Cody; Singhal, Udit; Bisaro, David M

    2015-03-01

    Both posttranscriptional and transcriptional gene silencing (PTGS and TGS, respectively) participate in defense against the DNA-containing geminiviruses. As a countermeasure, members of the genus Begomovirus (e.g., Cabbage leaf curl virus) encode an AL2 protein that is both a transcriptional activator and a silencing suppressor. The related L2 protein of Beet curly top virus (genus Curtovirus) lacks transcription activation activity. Previous studies showed that both AL2 and L2 suppress silencing by a mechanism that correlates with adenosine kinase (ADK) inhibition, while AL2 in addition activates transcription of cellular genes that negatively regulate silencing pathways. The goal of this study was to clarify the general means by which these viral proteins inhibit various aspects of silencing. We confirmed that AL2 inhibits systemic silencing spread by a mechanism that requires transcription activation activity. Surprisingly, we also found that reversal of PTGS and TGS by ADK inactivation depended on whether experiments were conducted in vegetative or reproductive Nicotiana benthamiana plants (i.e., before or after the vegetative-to-reproductive transition). While AL2 was able to reverse silencing in both vegetative and reproductive plants, L2 and ADK inhibition were effective only in vegetative plants. This suggests that silencing maintenance mechanisms can change during development or in response to stress. Remarkably, we also observed that AL2 lacking its transcription activation domain could reverse TGS in reproductive plants, revealing a third, previously unsuspected AL2 suppression mechanism that depends on neither ADK inactivation nor transcription activation. RNA silencing in plants is a multivalent antiviral defense, and viruses respond by elaborating multiple and sometimes multifunctional proteins that inhibit various aspects of silencing. The studies described here add an additional layer of complexity to this interplay. By examining geminivirus AL2 and

  13. Les voix du silence des rescapés de la Shoah : un retour à la vie ?

    Directory of Open Access Journals (Sweden)

    Fernande Ruiz Quemoun

    2015-11-01

    Full Text Available This paper shows the analysis of three autofiction comic books focussed on different silences of deported during and after the Shoah. The heros are Jewish children who survived hiding in silence thanks to the solidarity of the Righteous among the Nations. The analysis of these three comics, L'enfant cachée (Lizano, Dauvillier & Salsedo, Deuxième génération (Kichka and L’agneau qui ne voulait pas être un mouton (Jean & Zad, shows the voice of three survivors who man-aged to break their silence of more than sixty years. We will focus on the God silence, the silence of the rescued who prefers to say nothing, which right to say was denied, who has disappeared in ashes... We will emphasize the memorial literature of trials authors Wieviorka, Levinas and Friedemann, among others.

  14. Seismic attenuation system for a nuclear reactor

    Energy Technology Data Exchange (ETDEWEB)

    Liszkai, Tamas; Cadell, Seth

    2018-01-30

    A system for attenuating seismic forces includes a reactor pressure vessel containing nuclear fuel and a containment vessel that houses the reactor pressure vessel. Both the reactor pressure vessel and the containment vessel include a bottom head. Additionally, the system includes a base support to contact a support surface on which the containment vessel is positioned in a substantially vertical orientation. An attenuation device is located between the bottom head of the reactor pressure vessel and the bottom head of the containment vessel. Seismic forces that travel from the base support to the reactor pressure vessel via the containment vessel are attenuated by the attenuation device in a direction that is substantially lateral to the vertical orientation of the containment vessel.

  15. Ultrasonic attenuation in glassy crystalline cyclohexanol

    OpenAIRE

    Saint Paul , M.; Nava , R.

    1983-01-01

    Ultrasonic attenuation measurements at 100 MHz on the orientationally disordered crystalline phase of cyclohexanol are reported. The results provide additional evidence that the freezing process of the orientational disorder of the molecules in the crystal lattice is a relaxational phenomenon.

  16. Attenuation measurements in solutions of some carbohydrates

    International Nuclear Information System (INIS)

    Gagandeep; Singh, K.; Lark, B.S.; Sahota, H.S.

    2000-01-01

    The linear attenuation coefficients in aqueous solutions of three carbohydrates, glucose (C 6 H 12 O 6 ), maltose monohydrate (C 12 H 22 O 11 ·H 2 O), and sucrose (C 12 H 22 O 11 ), were determined at 81, 356, 511, 662, 1,173, and 1,332 keV by the gamma-ray transmission method in a good geometry setup. From the precisely measured densities of these solutions, mass attenuation coefficients were then obtained that varied systematically with the corresponding changes in the concentrations (g/cm 3 ) of these solutions. The experimental results were used in terms of effective atomic numbers and electron densities. A comparison between experimental and theoretical values of attenuation coefficients has proven that the study has a potential application for the determination of attenuation coefficients of solid solutes from their solutions without obtaining them in pure crystalline form

  17. Attenuation Measurements in Solutions of Some Carbohydrates

    International Nuclear Information System (INIS)

    Gagandeep; Singh, Kulwant; Lark, B.S.; Sahota, H.S.

    2000-01-01

    The linear attenuation coefficients in aqueous solutions of three carbohydrates, glucose (C 6 H 12 O 6 ), maltose monohydrate (C 12 H 22 O 11 .H 2 O), and sucrose (C 12 H 22 O 11 ), were determined at 81, 356, 511, 662, 1173, and 1332 keV by the gamma-ray transmission method in a good geometry setup. From the precisely measured densities of these solutions, mass attenuation coefficients were then obtained that varied systematically with the corresponding changes in the concentrations (g/cm 3 ) of these solutions. The experimental results were used in terms of effective atomic numbers and electron densities. A comparison between experimental and theoretical values of attenuation coefficients has proven that the study has a potential application for the determination of attenuation coefficients of solid solutes from their solutions without obtaining them in pure crystalline form

  18. Radiation-attenuated vaccine for lungworm disease

    International Nuclear Information System (INIS)

    Singh, C.M.

    1977-01-01

    The work done at the Indian Veternary Research Institute, Izatnagar, on the development of a vaccine for lungworm diseases is reported. Research work done includes: (1) studies on the epidemiology and the incidence of the lungworm infections, (ii) studies on the radiation-attenuated lungworm Dictyocaulus filaria vaccine, (iii) studies on other parasites using ionizing radiation, (iv) incidence of lungworm infection in sheep in Jammu and Kashmir State, (v) suitable dose of gamma radiation for attenuation, (vi) laboratory studies with radiation-attenuated D. filaria vaccine, (vii) serology of D. filaria infection, (viii) field trials with the radiation-attenuated vaccine, (ix) immune response of previously exposed lambs to vaccination, (x) comparative susceptibility of sheep and goats to infection with D. filaria, (xi) quantitative studies of D. filaria in lambs and (xii) production and supply of lungworm vaccine. (A.K.)

  19. 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.

  20. Post-Retrieval Extinction Attenuates Cocaine Memories

    OpenAIRE

    Sartor, Gregory C; Aston-Jones, Gary

    2013-01-01

    Recent studies have shown that post-retrieval extinction training attenuates fear and reward-related memories in both humans and rodents. This noninvasive, behavioral approach has the potential to be used in clinical settings to treat maladaptive memories that underlie several psychiatric disorders, including drug addiction. However, few studies to date have used a post-retrieval extinction approach to attenuate addiction-related memories. In the current study, we attempted to disrupt cocaine...

  1. Attenuation of Shock Waves using Perforated Plates

    Science.gov (United States)

    Pavan Kumar, CH V. L. C. S.; Hitesh Reddy, C.; Rahul Sai, L.; Dharani Kumar, K. S. S.; Nagaraja, S. R.

    2017-08-01

    The shock/blast waves generated due to explosions cause wide spread damage to the objects in its path. Different techniques have been used to attenuate shock wave over pressure, to reduce the catastrophic effects. Perforated plates can be used effectively to attenuate the shock wave pressure. In this paper shock wave interaction with perforated plates is simulated using COMSOL multiphysics software. The pressure drop varied from 43.75% to 26% for porosity varying from 10% to 40.

  2. Development of male sterility by silencing Bcp1 gene of Arabidopsis ...

    African Journals Online (AJOL)

    The development of male sterility is one of the most important steps in hybrid seed production. Several methods for the abortion of pollens based on conventional as well as genetic engineering are reported for the various crop species. Here we have investigated the use of RNA interference (RNAi) technology to silence a ...

  3. KDR gene silencing inhibits proliferation of A549 cells and enhances their sensitivity to docetaxel.

    Science.gov (United States)

    Wei, R; Zang, J-P

    2015-11-23

    We investigated the effects of kinase-domain insert containing receptor (KDR) gene silencing on the proliferation of A549 cells and their sensitivity to docetaxel. After designing and synthesizing the KDR siRNA sequence, the sequence was transfected into A549 cells using Lipofectamine 2000. The expression of KDR mRNA and protein after KDR gene silencing was detected by reverse transcription-polymerase chain reaction and western blotting; A549 cell cycle was detected by flow cytometry. An MTT assay and colony formation was performed to determine the sensitivity of A549 cells to docetaxel after KDR gene silencing. After 48-h KDR gene silencing, KDR gene and protein expression significantly decreased (P A549 cell cycle was significantly arrested in G0/G1 phase, and the number of cells in S phase was reduced; the difference was statistically significant (P A549 cells to docetaxel showed a significant enhancement (P A549 cells, inhibit the proliferation of A549 cells, and enhance their sensitivity to docetaxel.

  4. Gene silencing of stearoyl-ACP desaturase enhances the stearic acid content in Chlamydomonas reinhardtii

    NARCIS (Netherlands)

    Jaeger, de L.; Springer, J.; Wolbert, E.J.H.; Martens, D.E.; Eggink, G.; Wijffels, R.H.

    2017-01-01

    In this study, stearoyl-ACP desaturase (SAD), the enzyme that converts stearic acid into oleic acid, is silenced by artificial microRNA in the green microalga Chlamydomonas reinhardtii. Two different constructs, which target different positions on the mRNA of stearoyl-ACP desaturase, were tested.

  5. The Relationship among Interactional Justice, Manager Trust and Teachers' Organizational Silence Behavior

    Science.gov (United States)

    Yangin, Demet; Elma, Cevat

    2017-01-01

    The purpose of this study was to determine the relationship between the manager trust and interactional justice perceptions and organizational silence behaviors of those teachers who work in primary and secondary schools. The research is based on the survey model and the population consists of 4761 teachers who worked in Samsun, Turkey. The sample…

  6. A Day of Silence, a Day of Truth, and a Lawsuit

    Science.gov (United States)

    Fusarelli, Bonnie C.; Eaton, Lucy E.

    2011-01-01

    This case study focuses on issues of freedom of speech and freedom of religion in public schools. It involves a rural, southern high school where a group of students participated in a Day of Silence. The school allowed the students to participate based on the principal's understanding of the students' First Amendment rights. However, the next day,…

  7. 'Checkmating HIV&AIDS': Using chess to break the silence in the ...

    African Journals Online (AJOL)

    In this article, I give an account of my 'Checkmating HIV&AIDS' action research project, which was an attempt to break the 'culture of silence' concerning HIV&AIDS and sex and sexuality in my classroom. In this project, I focused specifically on one code of sport, namely chess, and I point out and discuss the potential of ...

  8. [Effects of Sam68 gene silence on proliferation of acute T lymphoblastic leukemia cell line Jurkat].

    Science.gov (United States)

    Wang, Chi-Juan; Xu, Hua; Zhang, Hai-Rui; Wang, Jian; Lin, Ya-Ni; Pang, Tian-Xiang; Li, Qing-Hua

    2014-08-01

    This study was purpose to investigate the effect of Sam68 gene silence on proliferation of human acute T lymphoblastic leukemia cell line Jurkat. The sequence of shRNA targeting the site 531-552 of Sam68 mRNA was designed and chemically synthesized, then a single-vector lentiviral, Tet-inducible shRNA-Sam68 system (pLKO-Tet-On) was constructed; next the Jurkat cells were infected with lentivirus to create stable cell clones with regulatable Sam68 gene expression. The inhibitory efficiency of Sam68 gene was assayed by Real-time PCR and Western blot; the cell activity of Jurkat cells was detected with MTT assay; the change of colony forming potential of Jurkat cells was analyzed by colony forming test; the cell cycle distribution was tested by flow cytometry. The results indicated that the expression of Sam68 in experimental cells was statistically decreased as compared with that of the control cells; the cells activity and colony forming capacity of the Jurkat cells with Sam68 gene silence were significantly inhibited; with Sam68 gene silencing, the percentage of S phase cells was significantly increased, while the percentage of G2 phase cells was significantly decreased. It is concluded that the silencing Sam68 gene using shRNA interference can effectively inhibit the proliferation of human acute T lymphoblastic leukemia cell line Jurkat.

  9. The New Role of Librarians and Libraries: Removing the Silence Signs

    Science.gov (United States)

    Carriuolo, Nancy; Reis, Tovah

    2015-01-01

    An increasing number of institutions are freeing up shelf space in their libraries and moving in student services as well as a coffee shop and other lures such as flexible seating arrangements. Librarians are taking down the silence signs in all but the quiet study room and urging members of the academic community to meet, talk, research and…

  10. ADAM17 silencing in mouse colon carcinoma cells: the effect on tumoricidal cytokines and angiogenesis.

    Directory of Open Access Journals (Sweden)

    Sudipta Das

    Full Text Available ADAM17 (a disintegrin and metalloprotease 17 is a major sheddase for numerous growth factors, cytokines, receptors, and cell adhesion molecules and is often overexpressed in malignant cells. It is generally accepted that ADAM17 promotes tumor development via activating growth factors from the EGF family, thus facilitating autocrine stimulation of tumor cell proliferation and migration. Here we show, using MC38CEA murine colon carcinoma model, that ADAM17 also regulates tumor angiogenesis and cytokine profile. When ADAM17 was silenced in MC38CEA cells, in vivo tumor growth and in vitro cell motility were significantly diminished, but no effect was seen on in vitro cell proliferation. ADAM17-silencing was accompanied by decreased in vitro expression of vascular endothelial growth factor-A and matrix metalloprotease-9, which was consistent with the limited angiogenesis and slower growth seen in ADAM17-silenced tumors. Among the growth factors susceptible to shedding by ADAM17, neuregulin-1 was the only candidate to mediate the effects of ADAM17 on MC38CEA motility and tumor angiogenesis. Concentrations of TNF and IFNγ, cytokines that synergistically induced proapoptotic effects on MC38CEA cells, were significantly elevated in the lysates of ADAM17-silenced tumors compared to mock transfected controls, suggesting a possible role for ADAM17 in host immune suppression. These results introduce new, complex roles of ADAM17 in tumor progression, including its impact on the anti-tumor immune response.

  11. Improving self-directed learning/intercultural competencies: breaking the silence.

    Science.gov (United States)

    Kirkpatrick, Mary K; Esterhuizen, Philip; Jesse, Elizabeth; Brown, Sylvia T

    2015-01-01

    Nurse educators need to develop innovative, technological curricula that foster intercultural competencies as essential components of a university education and break the silence with respect to lesbian, gay, bisexual, transgender, and queer (LGBTQ) health. Goals are to foster using these competencies to make LGBTQ content explicit in nursing curricula and in their professional organizations to promote equality and lessen disparities in this group.

  12. 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.

  13. Shattering the silence: IDRC-Zubaan research speaks out on sexual ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    2016-06-14

    Jun 14, 2016 ... The silence surrounding sexual violence in South Asia has been shattered. The Zubaan Series on Sexual Violence and Impunity in South Asia, formally launched in New Delhi on May 21, 2016, presents severe statements about criminal justice systems in South Asia that turn their back on sexual violence, ...

  14. Silencing of the SlNAP7 gene influences plastid development and lycopene accumulation in tomato

    Science.gov (United States)

    Fu, Da-Qi; Meng, Lan-Huan; Zhu, Ben-Zhong; Zhu, Hong-Liang; Yan, Hua-Xue; Luo, Yun-Bo

    2016-12-01

    Ripening is an important stage of fruit development. To screen the genes associated with pigment formation in tomato fruit, a suppression subtractive hybridization (SSH) cDNA library was constructed by using tomato fruit in the green ripe and break ripe stages, and 129 differential genes were obtained. Using redness as a screening marker, virus-induced gene silencing (VIGS) of the differential genes was performed with a sprout vacuum-infiltration system (SVI). The results showed that silencing the SlNAP7 gene affected the chloroplast development of tomato leaves, manifesting as a photo-bleaching phenotype, and silenced fruit significantly affected the accumulation of lycopene, manifested as a yellow phenotype. In our study, we found that silencing the SlNAP7 gene downregulates the expression of the POR and PORA genes and destroys the normal development of the chloroplast. The expression of related genes included in the lycopene biosynthesis pathway was not significantly changed, but lycopene accumulation was significantly reduced in tomato fruit. Perhaps it was caused by the destruction of the chromoplast, which leads to the oxidation of lycopene. The results show that the SlNAP7 gene influences chloroplast development and lycopene accumulation in tomato.

  15. Graft-accelerated virus-induced gene silencing facilitates functional genomics in rose flowers.

    Science.gov (United States)

    Yan, Huijun; Shi, Shaochuan; Ma, Nan; Cao, Xiaoqian; Zhang, Hao; Qiu, Xianqin; Wang, Qigang; Jian, Hongying; Zhou, Ningning; Zhang, Zhao; Tang, Kaixue

    2018-01-01

    Rose has emerged as a model ornamental plant for studies of flower development, senescence, and morphology, as well as the metabolism of floral fragrances and colors. Virus-induced gene silencing (VIGS) has long been used in functional genomics studies of rose by vacuum infiltration of cuttings or seedlings with an Agrobacterium suspension carrying TRV-derived vectors. However, VIGS in rose flowers remains a challenge because of its low efficiency and long time to establish silencing. Here we present a novel and rapid VIGS method that can be used to analyze gene function in rose, called 'graft-accelerated VIGS', where axillary sprouts are cut from the rose plant and vacuum infiltrated with Agrobacterium. The inoculated scions are then grafted back onto the plants to flower and silencing phenotypes can be observed within 5 weeks, post-infiltration. Using this new method, we successfully silenced expression of the RhDFR1, RhAG, and RhNUDX1 in rose flowers, and affected their color, petal number, as well as fragrance, respectively. This grafting method will facilitate high-throughput functional analysis of genes in rose flowers. Importantly, it may also be applied to other woody species that are not currently amenable to VIGS by conventional leaf or plantlet/seedling infiltration methods. © 2017 Institute of Botany, Chinese Academy of Sciences.

  16. Silencing Agrobacterium oncogenes in transgenic grapevine results in strain-specific crown gall resistance.

    Science.gov (United States)

    Galambos, A; Zok, A; Kuczmog, A; Oláh, R; Putnoky, P; Ream, W; Szegedi, E

    2013-11-01

    Grapevine rootstock transformed with an Agrobacterium oncogene-silencing transgene was resistant to certain Agrobacterium strains but sensitive to others. Thus, genetic diversity of Agrobacterium oncogenes may limit engineering crown gall resistance. Crown gall disease of grapevine induced by Agrobacterium vitis or Agrobacterium tumefaciens causes serious economic losses in viticulture. To establish crown gall-resistant lines, somatic proembryos of Vitis berlandieri × V. rupestris cv. 'Richter 110' rootstock were transformed with an oncogene-silencing transgene based on iaaM and ipt oncogene sequences from octopine-type, tumor-inducing (Ti) plasmid pTiA6. Twenty-one transgenic lines were selected, and their transgenic nature was confirmed by polymerase chain reaction (PCR). These lines were inoculated with two A. tumefaciens and three A. vitis strains. Eight lines showed resistance to octopine-type A. tumefaciens A348. Resistance correlated with the expression of the silencing genes. However, oncogene silencing was mostly sequence specific because these lines did not abolish tumorigenesis by A. vitis strains or nopaline-type A. tumefaciens C58.

  17. Silence, pleasure and agency: sexuality of unmarried girls in Dakar, Senegal

    NARCIS (Netherlands)

    Eerdewijk, A.H.J.M. van

    2009-01-01

    The article investigates the way unmarried Muslim girls in contemporary Dakar construct their sexuality. It explores in what way and to what extent female sexuality is being silenced, and if any, in what way pleasure and sexual agency are present in the narratives of those girls about their intimate

  18. Spatio-temporal requirements for transposable element piRNA-mediated silencing during Drosophila oogenesis.

    Science.gov (United States)

    Dufourt, Jérémy; Dennis, Cynthia; Boivin, Antoine; Gueguen, Nathalie; Théron, Emmanuelle; Goriaux, Coline; Pouchin, Pierre; Ronsseray, Stéphane; Brasset, Emilie; Vaury, Chantal

    2014-02-01

    During Drosophila oogenesis, transposable element (TE) repression involves the Piwi-interacting RNA (piRNA) pathway which ensures genome integrity for the next generation. We developed a transgenic model to study repression of the Idefix retrotransposon in the germline. Using a candidate gene KD-approach, we identified differences in the spatio-temporal requirements of the piRNA pathway components for piRNA-mediated silencing. Some of them (Aub, Vasa, Spn-E) are necessary in very early stages of oogenesis within the germarium and appear to be less important for efficient TE silencing thereafter. Others (Piwi, Ago3, Mael) are required at all stages of oogenesis. Moreover, during early oogenesis, in the dividing cysts within the germarium, Idefix anti-sense transgenes escape host control, and this is associated with very low piwi expression. Silencing of P-element-based transgenes is also strongly weakened in these cysts. This region, termed the 'Piwiless pocket' or Pilp, may ensure that new TE insertions occur and are transmitted to the next generation, thereby contributing to genome dynamics. In contrast, piRNA-mediated silencing is strong in germline stem cells in which TE mobilization is tightly repressed ensuring the continued production of viable germline cysts.

  19. The shadow of silence on the sexual rights of married Iranian women.

    Science.gov (United States)

    Janghorban, Roksana; Latifnejad Roudsari, Robab; Taghipour, Ali; Abbasi, Mahmoud; Lottes, Ilsa

    2015-01-01

    There has been a recent shift in the field of sexual health, representing a move away from biomedical concerns to sexual rights frameworks. However, few studies on sexuality are based on a rights framework. The unspoken nature of sexuality in Iranian culture has led to a lack of national studies on the topic. The objective of this study was to explore the perceptions and experiences of married Iranian women on sexual rights in their sexual relationships. In this grounded theory study, 37 participants (25 married women, 5 husbands, and 7 midwives) were selected. Data were collected through in-depth interviews and analyzed through open, axial, and selective coding using MAXQDA software version 2007. The analysis revealed the core category of "sexual interaction in the shadow of silence." The interrelated categories subsumed under the core category included adopting a strategy of silence, trying to negotiate sex, seeking help, and sexual adjustment. The silence originating from women's interactions with their families and society, from girlhood to womanhood, was identified as the core concept in Iranian women's experiences of sexual rights. A focus on husbands' roles seems salient because they can direct or alter some learned feminine roles, especially silence regarding sexual matters, which then affects the realization of women's sexual rights.

  20. Performances of Student Activism: Sound, Silence, Gender, and Dis/ability

    Science.gov (United States)

    Pasque, Penny A.; Vargas, Juanita Gamez

    2014-01-01

    This chapter explores the various performances of activism by students through sound, silence, gender, and dis/ability and how these performances connect to social change efforts around issues such as human trafficking, homeless children, hunger, and children with varying abilities.

  1. 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.

  2. The Relationship between Organizational Climate and the Organizational Silence of Administrative Staff in Education Department

    Science.gov (United States)

    Pozveh, Asghar Zamani; Karimi, Fariba

    2016-01-01

    The aim of the present study was to determine the relationship between organizational climate and the organizational silence of administrative staff in Education Department in Isfahan. The research method was descriptive and correlational-type method. The study population was administrative staff of Education Department in Isfahan during the…

  3. In trans silencing properties of a tobacco transgene locus depend on its epigenetic state

    Czech Academy of Sciences Publication Activity Database

    Fojtová, Miloslava; Van Houdt, H.; Depicker, A.; Kovařík, Aleš

    2004-01-01

    Roč. 26, č. 3 (2004), s. 147 ISSN 0137-5881. [Congress of the Federation of European Societies of Plant Biology /14./. 23.08.2004-27.08.2004, Cracow] Keywords : plant transgenes * gene expression * silencing Subject RIV: BO - Biophysics

  4. Telomere Position Effect and Silencing of Transgenes near Telomeres in the Mouse¶

    Science.gov (United States)

    Pedram, Mehrdad; Sprung, Carl N.; Gao, Qing; Lo, Anthony W. I.; Reynolds, Gloria E.; Murnane, John P.

    2006-01-01

    Reversible transcriptional silencing of genes located near telomeres, termed the telomere position effect (TPE), is well characterized in Saccharomyces cerevisiae. TPE has also been observed in human tumor cell lines, but its function remains unknown. To investigate TPE in normal mammalian cells, we developed clones of mouse embryonic stem (ES) cells that contain single-copy marker genes integrated adjacent to different telomeres. Analysis of these telomeric transgenes demonstrated that they were expressed at very low levels compared to the same transgenes integrated at interstitial sites. Similar to the situation in yeast, but in contrast to studies with human tumor cell lines, TPE in mouse ES cells was not reversed with trichostatin A. Prolonged culturing without selection resulted in extensive DNA methylation and complete silencing of telomeric transgenes, which could be reversed by treatment with 5-azacytidine. Thus, complete silencing of the telomeric transgenes appears to involve a two-step process in which the initial repression is reinforced by DNA methylation. Extensive methylation of the telomeric transgenes was also observed in various tissues and embryonic fibroblasts isolated from transgenic mice. In contrast, telomeric transgenes were not silenced in ES cell lines isolated from 3-day-old preimplantation embryos, consistent with the hypothesis that TPE plays a role in the development of the embryo. PMID:16479005

  5. Transient receptor potential vanilloid 4 (TRPV4) silencing in Helicobacter pylori-infected human gastric epithelium.

    Science.gov (United States)

    Mihara, Hiroshi; Suzuki, Nobuhiro; Muhammad, Jibran Sualeh; Nanjo, Sohachi; Ando, Takayuki; Fujinami, Haruka; Kajiura, Shinya; Hosokawa, Ayumu; Sugiyama, Toshiro

    2017-04-01

    Helicobacter pylori (HP) infection induces methylation silencing of specific genes in gastric epithelium. Various stimuli activate the nonselective cation channel TRPV4, which is expressed in gastric epithelium where it detects mechanical stimuli and promotes ATP release. As CpG islands in TRPV4 are methylated in HP-infected gastric epithelium, we evaluated HP infection-dependent changes in TRPV4 expression in gastric epithelium. Human gastric biopsy samples, a human gastric cancer cell line (AGS), and a normal gastric epithelial cell line (GES-1) were used to detect TRPV4 mRNA and protein expression by RT-PCR and Western blotting, respectively. Ca 2+ imaging was used to evaluate TRPV4 ion channel activity. TRPV4 methylation status was assessed by methylation-specific PCR (MSP). ATP release was measured by a luciferin-luciferase assay. TRPV4 mRNA and protein were detected in human gastric biopsy samples and in GES-1 cells. MSP and demethylation assays showed TRPV4 methylation silencing in AGS cells. HP coculture directly induced methylation silencing of TRPV4 in GES-1 cells. In human samples, HP infection was associated with TRPV4 methylation silencing that recovered after HP eradication in a time-dependent manner. HP infection-dependent DNA methylation suppressed TRPV4 expression in human gastric epithelia, suggesting that TRPV4 methylation may be involved in HP-associated dyspepsia. © 2016 The Authors. Helicobacter Published by John Wiley & Sons Ltd.

  6. Socrates, Augustine, and Paul Gauguin on the Reciprocity between Speech and Silence in Education

    Science.gov (United States)

    Caranfa, Angelo

    2013-01-01

    While most educational practices today place an excessive amount of attention on discourse, this article attaches great importance to the reciprocity between speech and silence by drawing from the writings of Plato's Socrates, Augustine, and Paul Gauguin for whom this reciprocity is of the essence in learning. These three figures teach that…

  7. Silencing effect of shRNA expression vectors with stem length of 21 ...

    African Journals Online (AJOL)

    In this study, shRNA vectors having different stem length were constructed and their silencing effect was tested in mouse embryonic fibroblast and in vivo. Interfering RNAs were designed with stems of 21, 27, and 29 bp. The enhanced green fluorescent protein gene was used as target gene. The synthesized single strands ...

  8. The potential of virus-induced gene silencing for speeding up functional characterization of plant genes

    NARCIS (Netherlands)

    Benedito, V.A.; Visser, P.B.; Angenent, G.C.; Krens, F.A.

    2004-01-01

    Virus-induced gene silencing (VIGS) has been shown to be of great potential in plant reverse genetics. Advantages of VIGS over other approaches, such as T-DNA or transposon tagging, include the circumvention of plant transformation, methodological simplicity and robustness, and speedy results. These

  9. Silencing an Anopheles gambiae Catalase and Sulfhydryl Oxidase Increases Mosquito Mortality After a Blood Meal

    Science.gov (United States)

    Magalhaes, T.; Brackney, D.E.; Beier, J.C.; Foy, B.D.

    2009-01-01

    Catalase is a potent antioxidant, likely involved in post-blood meal homeostasis in mosquitoes. This enzyme breaks down H2O2, preventing the formation of the hydroxyl radical (HO•). Quiescins are newly classified sulfhydryl oxidases that bear a thioredoxin motif at the N-terminal and an ERV1-like portion at the C-terminal. These proteins have a major role in generating disulfides in intra- or extracellular environments, and thus participate in redox reactions. In the search for molecules to serve as targets for novel anti-mosquito strategies, we have silenced a catalase and a putative quiescin/sulfhydryl oxidase (QSOX), from the African malaria vector Anopheles gambiae, through RNA interference (RNAi) experiments. We observed that the survival of catalase- and QSOX-silenced insects was reduced over controls following blood digestion, most likely due to the compromised ability of mosquitoes to scavenge and/or prevent damage caused by blood meal-derived oxidative stress. The higher mortality effect was more accentuated in catalase-silenced mosquitoes, where catalase activity was reduced to low levels. Lipid peroxidation was higher in QSOX-silenced mosquitoes suggesting the involvement of this protein in redox homeostasis following a blood meal. This study points to the potential of molecules involved in antioxidant response and redox metabolism to serve as targets of novel anti-mosquito strategies and offers a screening methodology for finding targetable mosquito molecules. PMID:18454489

  10. Between Silence and Speech: Autoethnography as an Otherness-Resisting Practice

    Science.gov (United States)

    Tsalach, Calanit

    2013-01-01

    In this article I wish to trace three everyday moments in which my Mizrahi Ethnic Identity intersects with the academic one, and then extract experiences of ethnic otherness that are built within those moments. Exploring these moments while considering Mizrahi identity construction, practices of otherness, and terms of silences enables a more…

  11. After Brown U.'s Report on Slavery, Silence (So Far)

    Science.gov (United States)

    Bartlett, Thomas

    2006-01-01

    This article, discusses Brown University's slavery report, a 106-page narrative examination of the early connections between Brown University and slavery, that has been greeted--so far--with silence. The report, done at the behest of Ruth J. Simmons, Brown's president and herself a descendant of slaves, is an unsparing look at a shameful side of…

  12. An Eastern Learning Paradox: Paradoxes in Two Korean Mathematics Teachers' Pedagogy of Silence in the Classroom

    Science.gov (United States)

    Lee, Kyeonghwa; Sriraman, Bharath

    2013-01-01

    Eastern philosophies of education such as Confucianism and Taosim advocate the use of silence in the teacher-pupil tradition of pedagogy. We investigate contemporary classrooms in Korea, and study whether teachers in Korea today incorporate this method implicitly or explicitly in their classrooms. Empirical data in the form of video-taped…

  13. Hearing Silence: Toward a Mixed-Method Approach for Studying Genres' Exclusionary Potential

    Science.gov (United States)

    Randazzo, Chalice

    2015-01-01

    Traditional Rhetorical Genre Study (RGS) methods are not well adapted to study exclusion because excluded information and people are typically absent from the genre, and some excluded information is simply unrelated to the genre because of genre conventions or social context. Within genre-based silences, how can scholars differentiate between an…

  14. Novel RNA Duplex Locks HIV-1 in a Latent State via Chromatin-mediated Transcriptional Silencing

    Directory of Open Access Journals (Sweden)

    Chantelle Ahlenstiel

    2015-01-01

    Full Text Available Transcriptional gene silencing (TGS of mammalian genes can be induced by short interfering RNA (siRNA targeting promoter regions. We previously reported potent TGS of HIV-1 by siRNA (PromA, which targets tandem NF-κB motifs within the viral 5′LTR. In this study, we screened a siRNA panel with the aim of identifying novel 5′LTR targets, to provide multiplexing potential with enhanced viral silencing and application toward developing alternate therapeutic strategies. Systematic examination identified a novel siRNA target, si143, confirmed to induce TGS as the silencing mechanism. TGS was prolonged with virus suppression >12 days, despite a limited ability to induce post- TGS. Epigenetic changes associated with silencing were suggested by partial reversal by histone deacetylase inhibitors and confirmed by chromatin immunoprecipitation analyses, which showed induction of H3K27me3 and H3K9me3, reduction in H3K9Ac, and recruitment of argonaute-1, all characteristic marks of heterochromatin and TGS. Together, these epigenetic changes mimic those associated with HIV-1 latency. Further, robust resistance to reactivation was observed in the J-Lat 9.2 cell latency model, when transduced with shPromA and/or sh143. These data support si/shRNA-mediated TGS approaches to HIV-1 and provide alternate targets to pursue a functional cure, whereby the viral reservoir is locked in latency following antiretroviral therapy cessation.

  15. The Shadow of Silence on the Sexual Rights of Married Iranian Women

    Directory of Open Access Journals (Sweden)

    Roksana Janghorban

    2015-01-01

    Full Text Available There has been a recent shift in the field of sexual health, representing a move away from biomedical concerns to sexual rights frameworks. However, few studies on sexuality are based on a rights framework. The unspoken nature of sexuality in Iranian culture has led to a lack of national studies on the topic. The objective of this study was to explore the perceptions and experiences of married Iranian women on sexual rights in their sexual relationships. In this grounded theory study, 37 participants (25 married women, 5 husbands, and 7 midwives were selected. Data were collected through in-depth interviews and analyzed through open, axial, and selective coding using MAXQDA software version 2007. The analysis revealed the core category of “sexual interaction in the shadow of silence.” The interrelated categories subsumed under the core category included adopting a strategy of silence, trying to negotiate sex, seeking help, and sexual adjustment. The silence originating from women’s interactions with their families and society, from girlhood to womanhood, was identified as the core concept in Iranian women’s experiences of sexual rights. A focus on husbands’ roles seems salient because they can direct or alter some learned feminine roles, especially silence regarding sexual matters, which then affects the realization of women’s sexual rights.

  16. CRISPR Interference Efficiently Induces Specific and Reversible Gene Silencing in Human iPSCs

    DEFF Research Database (Denmark)

    Mandegar, Mohammad A.; Huebsch, Nathaniel; Frolov, Ekaterina B.

    2016-01-01

    repression system is tunable and has the potential to silence single alleles. Compared with CRISPR nuclease (CRISPRn), CRISPRi gene repression is more efficient and homogenous across cell populations. The CRISPRi system in iPSCs provides a powerful platform to perform genome-scale screens in a wide range...

  17. Silence in Official Representations of History: Implications for National Identity and Intergroup Relations

    Directory of Open Access Journals (Sweden)

    Tuğçe Kurtiş

    2018-01-01

    Full Text Available Dominant representations of history evolve through differential exercise of power to enable memory of collective triumphs and silence memory of collective misdeeds. We examined silence regarding minorities in official constructions of history and the implications of this silence for national identity and intergroup relations in Turkey. A content analysis of official constructions of history inscribed in Turkish national university admissions exams (Study 1 revealed an emphasis on celebratory events, silence about ethnic and religious minorities, and a construction of national identity in ethno-cultural (e.g., as “Turk” and “Muslim” rather than civic terms (e.g., in terms of citizenship. An investigation with Turkish participants (Study 2 revealed that denial of historical information regarding minority populations documented in sources outside the national curriculum was associated with greater endorsement of ethno-cultural constructions of identity and less support for minority rights and freedom of expression. We discuss the liberatory potential of alternative forms of historical knowledge to promote more inclusive models of identification and improve intergroup relations.

  18. On the Grammar of Silence: The Structure of My Undocumented Immigrant Writer's Block

    Science.gov (United States)

    Ledesma, Alberto

    2015-01-01

    In this reflective essay, Alberto Ledesma explores how being undocumented can produce a particular form of writer's block. He argues that there is a pattern of predictable silences and obfuscations inherent in all undocumented immigrant autobiographies that cannot be easily negotiated when undocumented students are asked to write about "their…

  19. Voicing and silence periods in daily and weekly vocalizations of teachers

    NARCIS (Netherlands)

    Titze, Ingo R.; Hunter, Eric J.; Svec, Jan G.

    The National Center for Voice and Speech (NCVS) data bank on voice dosimetry was used to study the distributions of continuous voicing periods and silence periods in 31 teachers over the duration of two weeks. Recordings were made during all awake hours of the day. Voicing periods were grouped into

  20. Breaking the culture of silence in checkmating HIV/AIDS as a ...

    African Journals Online (AJOL)

    In my investigation I set out to break the HIV/AIDS culture of silence and emphasize the role of the teacher as a researcher and critical change agent in an HIV/AIDS challenged society. My work demonstrates how teachers could play such a role by encouraging learners' participation in sport. The sport, I focussed on in my ...

  1. The splicing machinery promotes RNA-directed DNA methylation and transcriptional silencing in Arabidopsis

    Science.gov (United States)

    Zhang, Cui-Jun; Zhou, Jin-Xing; Liu, Jun; Ma, Ze-Yang; Zhang, Su-Wei; Dou, Kun; Huang, Huan-Wei; Cai, Tao; Liu, Renyi; Zhu, Jian-Kang; He, Xin-Jian

    2013-01-01

    DNA methylation in transposons and other DNA repeats is conserved in plants as well as in animals. In Arabidopsis thaliana, an RNA-directed DNA methylation (RdDM) pathway directs de novo DNA methylation. We performed a forward genetic screen for suppressors of the DNA demethylase mutant ros1 and identified a novel Zinc-finger and OCRE domain-containing Protein 1 (ZOP1) that promotes Pol IV-dependent siRNA accumulation, DNA methylation, and transcriptional silencing. Whole-genome methods disclosed the genome-wide effects of zop1 on Pol IV-dependent siRNA accumulation and DNA methylation, suggesting that ZOP1 has both RdDM-dependent and -independent roles in transcriptional silencing. We demonstrated that ZOP1 is a pre-mRNA splicing factor that associates with several typical components of the splicing machinery as well as with Pol II. Immunofluorescence assay revealed that ZOP1 overlaps with Cajal body and is partially colocalized with NRPE1 and DRM2. Moreover, we found that the other development-defective splicing mutants tested including mac3a3b, mos4, mos12 and mos14 show defects in RdDM and transcriptional silencing. We propose that the splicing machinery rather than specific splicing factors is involved in promoting RdDM and transcriptional silencing. PMID:23524848

  2. "Making a Way": Young Women Using Literacy and Language to Resist the Politics of Silencing

    Science.gov (United States)

    Wissman, Kelly K.

    2007-01-01

    Urban public schools are often contexts in which students are beset with silencing, surveillance, and low expectations. These conditions present distinct and critical challenges to young women. This article explores the language and literacy practices that emerged in an in-school elective writing and photography course designed with and for young…

  3. Genome reactivation after the silence in mitosis: recapitulating mechanisms of development?

    Science.gov (United States)

    Zaret, Kenneth S

    2014-04-28

    Transcription is silenced during mitosis and reactivated at mitotic exit. The dynamics and identities of "bookmarking" transcription factors and chromatin marks that mediate reactivation often recapitulate those observed during cell identity establishment in development. Thus, features of postmitotic gene reactivation can provide insights into mechanisms of developmental cell fate establishment. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. A new component of the Nasonia sex determining cascade is maternally silenced and regulates transformer expression.

    Science.gov (United States)

    Verhulst, Eveline C; Lynch, Jeremy A; Bopp, Daniel; Beukeboom, Leo W; van de Zande, Louis

    2013-01-01

    Although sex determination is a universal process in sexually reproducing organisms, sex determination pathways are among the most highly variable genetic systems found in nature. Nevertheless, general principles can be identified among the diversity, like the central role of transformer (tra) in insects. When a functional TRA protein is produced in early embryogenesis, the female sex determining route is activated, while prevention of TRA production leads to male development. In dipterans, male development is achieved by prevention of female-specific splicing of tra mRNA, either mediated by X-chromosome dose or masculinizing factors. In Hymenoptera, which have haplodiploid sex determination, complementary sex determination and maternal imprinting have been identified to regulate timely TRA production. In the parasitoid Nasonia, zygotic transformer (Nvtra) expression and splicing is regulated by a combination of maternal provision of Nvtra mRNA and silencing of Nvtra expression in unfertilized eggs. It is unclear, however, if this silencing is directly on the tra locus or whether it is mediated through maternal silencing of a trans-acting factor. Here we show that in Nasonia, female sex determination is dependent on zygotic activation of Nvtra expression by an as yet unknown factor. This factor, which we propose to term womanizer (wom), is maternally silenced during oogenesis to ensure male development in unfertilized eggs. This finding implicates the upstream recruitment of a novel gene in the Nasonia sex determining cascade and supports the notion that sex determining cascades can rapidly change by adding new components on top of existing regulators.

  5. 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

  6. 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

  7. 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

  8. Processing of abasic DNA clusters in hApeI-silenced primary ...

    Indian Academy of Sciences (India)

    Eagle Medium; DSB, double-strand break; DTT, dithiothreitol; EDTA, ethylenediaminetetraacetic acid; HEPES, .... #3 to be used for RNA-silencing experiments. ..... and HeLa cells (Fantini et al. 2008). Although a non-viral- mediated approach is effective for ApeI RNA interference experiments involving cancer cell lines, there ...

  9. The Sounds of Silence: American History Textbook Representations of Non-Violence and the Abolition Movement

    Science.gov (United States)

    Stoskopf, Alan; Bermudez, Angela

    2017-01-01

    In this paper we examine how the Abolition Movement's approach to non-violent resistance has been silenced in four American history textbooks. Despite extensive research that reveals an extensive network of groups dedicated to the peaceful abolishment of slavery little of this historical record is included in the textbooks. Instead, a skewed…

  10. The Silencing of the Knowledge-Base in Early Childhood Education and Care Professionalism

    Science.gov (United States)

    Campbell-Barr, Verity

    2018-01-01

    It is widely accepted that the early childhood education and care (ECEC) workforce is central to the quality of services. Modernist constructs of quality signal the importance of qualifications for quality, but the preoccupation with qualification levels silences questions about the knowledge required of ECEC professionals. Postmodern perspectives…

  11. RNAi-mediated gene silencing as a principle of action of venoms and poisons.

    Science.gov (United States)

    Pereira, Tiago Campos; Lopes-Cendes, Iscia

    2008-01-01

    RNA interference (RNAi) is a natural phenomenon in which double-stranded RNA molecules (dsRNAs) promote silencing of genes with similar sequence. It is noteworthy that in some instances the effects of gene silencing are similar to those caused by venoms and natural poisons (e.g., hemorrhage and low blood pressure). This observation raises the possibility that venomous/poisonous species in fact produce dsRNAs in their venoms/poisons and leading to the deleterious effects in the victim by RNAi-mediated gene silencing. Two approaches could be used to test this hypothesis, first, the neutralization of the dsRNAs and comparing to a non-treated venom sample; and second, to identify the dsRNA present in the venom and attempt to artificially reproduce its effects in the laboratory. In addition, we present three innovative treatment strategies for accidental interactions with venomous or poisonous species. RNAi has several roles in biological systems: gene regulation, antiviral defense, transposon silencing and heterochromatin formation. The hypothesis presented here provides a new role: a natural attack mechanism.

  12. Silencing honey bee naked cuticle (nkd) reduces Nosema ceranae replication and disease levels

    Science.gov (United States)

    Nosema ceranae is a new and emerging microsporidian parasite of European honey bees, Apis mellifera that has been implicated in alarming colony losses worldwide. RNA interference (RNAi), a post-transcriptional gene silencing mechanism, has emerged as a potent and specific strategy for controlling in...

  13. Breaking the Culture of Silence in Checkmating HIV/AIDS as a Teacher-Researcher

    Science.gov (United States)

    Esau, O.

    2010-01-01

    In my investigation I set out to break the HIV/AIDS culture of silence and emphasize the role of the teacher as a researcher and critical change agent in an HIV/AIDS challenged society. My work demonstrates how teachers could play such a role by encouraging learners' participation in sport. The sport, I focussed on in my action research project…

  14. Mechanisms of geometrical seismic attenuation

    Directory of Open Access Journals (Sweden)

    Igor B. Morozov

    2011-07-01

    Full Text Available In several recent reports, we have explained the frequency dependence of the apparent seismic quality-factor (Q observed in many studies according to the effects of geometrical attenuation, which was defined as the zero-frequency limit of the temporal attenuation coefficient. In particular, geometrical attenuation was found to be positive for most waves traveling within the lithosphere. Here, we present three theoretical models that illustrate the origin of this geometrical attenuation, and we investigate the causes of its preferential positive values. In addition, we discuss the physical basis and limitations of both the conventional and new attenuation models. For waves in media with slowly varying properties, geometrical attenuation is caused by variations in the wavefront curvature, which can be both positive (for defocusing and negative (for focusing. In media with velocity/density contrasts, incoherent reflectivity leads to geometrical-attenuation coefficients which are proportional to the mean squared reflectivity and are always positive. For «coherent» reflectivity, the geometrical attenuation is approximately zero, and the attenuation process can be described according to the concept of «scattering Q». However, the true meaning of this parameter is in describing the mean reflectivity within the medium, and not that of the traditional resonator quality factor known in mechanics. The general conclusion from these models is that non-zero and often positive levels of geometrical attenuation are common in realistic, heterogeneous media, both observationally and theoretically. When transformed into the conventional Q-factor form, this positive geometrical attenuation leads to Q values that quickly increase with frequency. These predictions show that the positive frequency-dependent Q observed in many datasets might represent artifacts of the transformations of the attenuation coefficients into Q.

  1. Maximum likelihood estimation of the attenuated ultrasound pulse

    DEFF Research Database (Denmark)

    Rasmussen, Klaus Bolding

    1994-01-01

    The attenuated ultrasound pulse is divided into two parts: a stationary basic pulse and a nonstationary attenuation pulse. A standard ARMA model is used for the basic pulse, and a nonstandard ARMA model is derived for the attenuation pulse. The maximum likelihood estimator of the attenuated...

  2. Lg Attenuation Modeling in the Middle East

    Science.gov (United States)

    Pasyanos, M. E.; Matzel, E. M.; Walter, W. R.; Rodgers, A. J.

    2008-12-01

    We present a broadband tomographic model of Lg attenuation in the Middle East derived from source- and site-corrected amplitudes. The study region spans from Turkey through the Arabian Peninsula and Iran to Pakistan, Afghanistan, and northwest India. Absolute amplitude measurements are made on hand-selected and carefully windowed seismograms for tens of stations and thousands of crustal earthquakes resulting in excellent coverage of the region. We have modified the standard attenuation tomography technique to more explicitly define the earthquake source expression in terms of the seismic moment. This facilitates the use of the model to predict the expected amplitudes of new events, an important consideration for earthquake hazard or explosion monitoring applications. We will discuss the updated method and implications of this parameterization. A conjugate gradient method is used to tomographically invert the amplitude dataset of over 8000 paths. We solve for Q variation, as well as site and source terms, for a wide range of frequencies ranging from 0.5 -- 10 Hz. The attenuation results have a strong correlation to tectonics. Shields have low attenuation, while tectonic regions have high attenuation, with the highest attenuation at 1 Hz found in eastern Turkey. The results also compare favorably to other studies in the region made using Lg propagation efficiency, Lg/Pg amplitude ratios and two-station methods. We tomographically invert the amplitude measurements for each frequency independently. In doing so, it appears the frequency-dependence of attenuation is not compatible with the power law representation of Q(f). This research was performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number DE-AC52-07NA27344. This is LLNL contribution LLNL-ABS-406761.

  3. 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

  4. Comparison of non-attenuation corrected and attenuation corrected myocardial perfusion SPE

    Directory of Open Access Journals (Sweden)

    Hasan Raza

    2016-09-01

    Conclusion: This study demonstrates that CT based attenuation corrected Tc-99mm sestamibi SPECT myocardial perfusion imaging significantly improved the specificity of the RCA territory compared with non-attenuation corrected Tc-99mm sestamibi SPECT myocardial perfusion imaging in both genders irrespective of BMI.

  5. Fat Attenuation at CT in Anorexia Nervosa

    Science.gov (United States)

    Gill, Corey M.; Torriani, Martin; Murphy, Rachel; Harris, Tamara B.; Miller, Karen K.; Klibanski, Anne

    2016-01-01

    Purpose To investigate the composition, cross-sectional area (CSA), and hormonal correlates of different fat depots in women with anorexia nervosa (AN) and control subjects with normal weights to find out whether patients with AN have lower fat CSA but higher attenuation than did control subjects and whether these changes may be mediated by gonadal steroids, cortisol, and thyroid hormones. Materials and Methods This study was institutional review board approved and HIPAA compliant. Written informed consent was obtained. Forty premenopausal women with AN and 40 normal-weight women of comparable age (mean age ± standard deviation, 26 years ± 5) were studied. All individuals underwent computed tomography of the abdomen and thigh with a calibration phantom. Abdominal subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), thigh SAT, and thigh intermuscular adipose tissue CSA and attenuation were quantified. Serum estradiol, thyroid hormones, and urinary free cortisol levels were assessed. Variables were compared by using analysis of variance. Associations were examined by using linear regression analysis. Results Women with AN had higher fat attenuation than did control subjects (−100.1 to −46.7 HU vs −117.6 to −61.8 HU, P < .0001), despite lower fat CSA (2.0–62.8 cm2 vs 5.5–185.9 cm2, P < .0001). VAT attenuation but not CSA was inversely associated with lowest prior lifetime body mass index in AN (r = −0.71, P = .006). Serum estradiol levels were inversely associated with fat attenuation (r = −0.34 to −0.61, P = .03 to <.0001) and were positively associated with fat CSA of all compartments (r = 0.42–0.64, P = .007 to <.0001). Thyroxine levels and urinary free cortisol levels were positively associated with thigh SAT attenuation (r = 0.64 [P = .006] and r = 0.68 [P = .0004], respectively) and were inversely associated with abdominal SAT and VAT CSA (r = −0.44 to −0.58, P = .04 to .02). Conclusion Women with AN have differences in fat

  6. 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

    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...... VIGS. Surprisingly, only evidence for spreading of the target region in the 5'-3' direction was obtained. This finding may help explain why the majority of target regions examined to date lie within the 3' region of transgenes....

  7. Elastic wave attenuation in rocks containing fluids

    International Nuclear Information System (INIS)

    Berryman, J.G.

    1986-01-01

    The low-frequency limit of Biot's theory of fluid-saturated porous media predicts that the coefficients for viscous attenuation of shear waves and of the fast compressional wave are proportional to the fluid permeability. Although the observed attenuation is generally in qualitative agreement with the theory, the magnitude of the observed attenuation coefficient in rocks is often more than an order of magnitude higher than expected. This apparent dilemma can be resolved without invoking other attenuation mechanisms if the intrinsic permeability of the rock is inhomogeneous and varies widely in magnitude. A simple calculation of the overall behavior of a layered porous material using local-flow Biot theory shows that the effective permeability for attenuation is the mean of the constituent permeabilities while the effective permeability for fluid flow is the harmonic mean. When the range of variation in the local permeability is one or more orders of magnitude, this difference in averaging method can easily explain some of the observed discrepancies

  8. Sound attenuation of tanker’s headphone

    Directory of Open Access Journals (Sweden)

    Rafał Młyński

    2015-03-01

    Full Text Available Crew of military vehicles, which is exposed to the noise associated with the engine running, as well as to shots from firearms, is equipped with headphones. The article presents the results of noise reduction by HC-98 headphone for steady state and impulsive noise. Two methods of research were used: sound attenuation measurements with participation of subjects and transmission loss measurements with the use of acoustic test fixture — device reflecting the properties of the head. Data for headphone were compared with noise reduction of two different, commonly used earmuffs (one light, the other strong limiting noise. The results indicated that measured headphone meets the requirements that allow for treating it as hearing protection, however, this headphone does not provide hearing protection such as earmuffs. Relatively low values of attenuation of acoustic impulses through the headphone versus the results for earmuffs were observed. Furthermore, in the case of headphone, in the frequency range 63-2000 Hz, the lower values of steady state noise sound attenuation, from about 2 up to even a 19 dB with respect to the attenuation of ear muffs were measured.[b]Keywords[/b]: acoustics, noise control, noise, sound attenuation

  9. A Novel AT-Rich DNA Recognition Mechanism for Bacterial Xenogeneic Silencer MvaT.

    Directory of Open Access Journals (Sweden)

    Pengfei Ding

    2015-06-01

    Full Text Available Bacterial xenogeneic silencing proteins selectively bind to and silence expression from many AT rich regions of the chromosome. They serve as master regulators of horizontally acquired DNA, including a large number of virulence genes. To date, three distinct families of xenogeneic silencers have been identified: H-NS of Proteobacteria, Lsr2 of the Actinomycetes, and MvaT of Pseudomonas sp. Although H-NS and Lsr2 family proteins are structurally different, they all recognize the AT-rich DNA minor groove through a common AT-hook-like motif, which is absent in the MvaT family. Thus, the DNA binding mechanism of MvaT has not been determined. Here, we report the characteristics of DNA sequences targeted by MvaT with protein binding microarrays, which indicates that MvaT prefers binding flexible DNA sequences with multiple TpA steps. We demonstrate that there are clear differences in sequence preferences between MvaT and the other two xenogeneic silencer families. We also determined the structure of the DNA-binding domain of MvaT in complex with a high affinity DNA dodecamer using solution NMR. This is the first experimental structure of a xenogeneic silencer in complex with DNA, which reveals that MvaT recognizes the AT-rich DNA both through base readout by an "AT-pincer" motif inserted into the minor groove and through shape readout by multiple lysine side chains interacting with the DNA sugar-phosphate backbone. Mutations of key MvaT residues for DNA binding confirm their importance with both in vitro and in vivo assays. This novel DNA binding mode enables MvaT to better tolerate GC-base pair interruptions in the binding site and less prefer A tract DNA when compared to H-NS and Lsr2. Comparison of MvaT with other bacterial xenogeneic silencers provides a clear picture that nature has evolved unique solutions for different bacterial genera to distinguish foreign from self DNA.

  10. Ultrasonic Phase Velocity and Attenuation in Emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Nesse, Oe.; Froeysa, K.E.

    1996-12-31

    This paper presents measurements of ultrasonic phase velocity and attenuation in emulsions in the frequency range 250 kHz to 14 MHz for volume fractions of dispersed phase varying from 2% to 80%. The experimental data are compared to theoretical predictions based on multiple scattering models. Good agreement is found between experimental data and theory for an oil-in-water emulsion at volume fractions up to 50%. For volume fractions of the dispersed phase above 50%, important discrepancies are found between the multiple scattering theories and the experiments for oil-in-water emulsions and for water-in-oil emulsions. However, measurements on water-in-oil emulsions and attenuation in emulsions of aliphatic oils in water deviate considerably from the theories. Measurements of phase velocity and attenuation in emulsions may provide information about droplet size, volume fraction of the dispersed phase and determine whether the emulsion is oil or water continuous. 10 refs., 6 figs.

  11. Finite Element Analysis of Honeycomb Impact Attenuator

    Science.gov (United States)

    Yang, Seung-Yong; Choi, Seung-Kyu; Kim, Nohyu

    To participate in Student Formula Society of Automotive Engineers (SAE) competitions, it is necessary to build an impact attenuator that would give an average deceleration not to exceed 20g when it runs into a rigid wall. Students can use numerical simulations or experimental test data to show that their car satisfies this safety requirement. A student group to study formula cars at the Korea University of Technology and Education has designed a vehicle to take part in a SAE competition, and a honeycomb structure was adopted as the impact attenuator. In this paper, finite element calculations were carried out to investigate the dynamic behavior of the honeycomb attenuator. Deceleration and deformation behaviors were studied. Effect of the yield strength was checked by comparing the numerical results. ABAQUS/Explicit finite element code was used.

  12. PSD95 gene specific siRNAs attenuate neuropathic pain through modulating neuron sensibility and postsynaptic CaMKIIα phosphorylation.

    Science.gov (United States)

    Le, Shen; Xu, Li; Wen, Chen; Li, Xu; Wei, Liu; Xue-rong, Yu; Yu-guang, Huang

    2011-12-01

    To observe the effects of PSD95 gene specific siRNAs on neuropathic pain relief, neuron viability, and postsynaptic calcium/calmodulin-dependent protein kinase IIα (CaMKIIα) phosphorylation in vitro and in vivo. Gene-specific siRNAs of rat PSD95 were synthesized chemically for transfection. Adult male Sprague-Dawley (SD) rats were randomly divided into 3 groups: naïve group (n=6), sham group (n=6), and sciatic nerve chronic constriction injury (CCI) group (n=24). The CCI group was further divided into 4 groups (n=6 in each group), which were pretreated with normal saline, transfection vehicle, negative control siRNAs, and PSD95 gene specific siRNAs respectively. All the subgroups received corresponding agents intrathecally for 3 days, started one day before the CCI of sciatic nerve. Both mechanical allodynia and thermal hyperalgesia were measured on post-operative day 3 and 7. PSD95 gene silenced NG108-15 cells were further stimulated by glutamate, with the cell viability and the expression/phosphorylation of CaMKIIα measured by MTT cell proliferation assay and Western blot, respectively. The siRNAs decreased PSD95 mRNA level significantly both in vivo and in vitro. Neuropathic pain rats pretreated with PSD95 gene specific siRNAs exhibited significant elevation in the mechanical withdrawal threshold and paw withdrawal thermal latency, without affecting the baseline nociception. PSD95 gene silencing enhanced neuronal tolerance against the glutamate excitotoxicity, meanwhile the phosphorylation of CaMKIIα Thr286 was attenuated. Pre-emptive administration of PSD95 gene specific siRNAs may attenuate the central sensitization CaMKIIα-related signaling cascades, leading to the relief of neuropathic pain.

  13. L'éthique du silence : le conflit d'intérêts explique-t-il le silence des employés?

    Science.gov (United States)

    Anderson, James

    2018-03-01

    Le silence des employés constitue une menace importante pour la réussite des organisations. Dans le présent article, les auteurs avancent que le silence dérive du conflit d'intérêts (CdI) structurel entre les employés et leur employeur. Cet argument repose sur la thèse également défendue dans l'article selon laquelle les leaders, qu'ils l'acceptent ou non, dépendent de leurs employés pour obtenir de l'information fiable sur le travail effectué, car ceux-ci connaissent intimement ce qu'ils font. La parole des employés devient donc une nécessité organisationnelle. C'est également une réalisation morale, car elle oblige l'individu à risquer ses intérêts personnels au profit de ceux de l'organisation. Les leaders doivent prendre des mesures pour atténuer les CdI et inciter les employés à s'exprimer. Le présent article leur fournit plusieurs stratégies en ce sens.

  14. Ce que l’on fait dire au silence : posture, ethos, image d’auteur How to make silence talk… Posture, ethos, author’s image

    Directory of Open Access Journals (Sweden)

    Jérôme Meizoz

    2009-10-01

    Full Text Available Après la parution de Postures littéraires (2007 cet article revient sur la visée méthodologique de la notion de « posture », en la confrontant à deux notions voisines, celles d’« ethos » et d’« image d’auteur ». Il propose de hiérarchiser ces trois notions dans un ensemble conceptuel. Une brève analyse du Silence de la mer (1942 de Vercors illustre cette réflexion.After the publication of Literary postures (2007, this article revisits the methodological approach based on the notion of “posture” by comparing it with two related notions, “ethos” and “author’s image”. It shows how these three notions can be organized into a hierarchy inside an integrated conceptual whole. A brief analysis of Vercors’ TheSilence of the Sea (1942 illustrates this proposition.

  15. Silencing of neurotropic flavivirus replication in the central nervous system by combining multiple microRNA target insertions in two distinct viral genome regions

    Science.gov (United States)

    Teterina, Natalya L.; Liu, Guangping; Maximova, Olga A.; Pletnev, Alexander G.

    2014-01-01

    In recent years, microRNA-targeting has become an effective strategy for selective control of tissue-tropism and pathogenesis of both DNA and RNA viruses. Here, using a neurotropic flavivirus as a model, we demonstrate that simultaneous miRNA targeting of the viral genome in the open reading frame and 3′-noncoding regions for brain-expressed miRNAs had an additive effect and produced a more potent attenuation of the virus compared to separate targeting of those regions. Multiple miRNA co-targeting of these two distantly located regions completely abolished the virus neurotropism as no viral replication was detected in the developing brain of neonatal mice. Furthermore, no viral antigens were detected in neurons, and neuronal integrity in the brain of mice was well preserved. This miRNA co-targeting approach can be adapted for other viruses in order to minimize their replication in a cell- or tissue-type specific manner, but most importantly, to prevent virus escape from miRNA-mediated silencing. PMID:24889244

  16. Fast Silencing Reveals a Lost Role for Reciprocal Inhibition in Locomotion

    Science.gov (United States)

    Moult, Peter R.; Cottrell, Glen A.; Li, Wen-Chang

    2013-01-01

    Summary Alternating contractions of antagonistic muscle groups during locomotion are generated by spinal “half-center” networks coupled in antiphase by reciprocal inhibition. It is widely thought that reciprocal inhibition only coordinates the activity of these muscles. We have devised two methods to rapidly and selectively silence neurons on just one side of Xenopus tadpole spinal cord and hindbrain, which generate swimming rhythms. Silencing activity on one side led to rapid cessation of activity on the other side. Analyses reveal that this resulted from the depression of reciprocal inhibition connecting the two sides. Although critical neurons in intact tadpoles are capable of pacemaker firing individually, an effect that could support motor rhythms without inhibition, the swimming network itself requires ∼23 min to regain rhythmic activity after blocking inhibition pharmacologically, implying some homeostatic changes. We conclude therefore that reciprocal inhibition is critical for the generation of normal locomotor rhythm. PMID:23312521

  17. Bidirectional transfer of RNAi between honey bee and Varroa destructor: Varroa gene silencing reduces Varroa population.

    Directory of Open Access Journals (Sweden)

    Yael Garbian

    2012-12-01

    Full Text Available The mite Varroa destructor is an obligatory ectoparasite of the honey bee (Apis mellifera and is one of the major threats to apiculture worldwide. We previously reported that honey bees fed on double-stranded RNA (dsRNA with a sequence homologous to that of the Israeli acute paralysis virus are protected from the viral disease. Here we show that dsRNA ingested by bees is transferred to the Varroa mite and from mite on to a parasitized bee. This cross-species, reciprocal exchange of dsRNA between bee and Varroa engendered targeted gene silencing in the latter, and resulted in an over 60% decrease in the mite population. Thus, transfer of gene-silencing-triggering molecules between this invertebrate host and its ectoparasite could lead to a conceptually novel approach to Varroa control.

  18. Global Effects on Gene Expression in Fission Yeast by Silencing and RNA Interference Machineries

    DEFF Research Database (Denmark)

    Hansen, Klavs R.; Burns, G.; Mata, J.

    2005-01-01

    Histone modifications influence gene expression in complex ways. The RNA interference (RNAi) machinery can repress transcription by recruiting histone-modifying enzymes to chromatin, although it is not clear whether this is a general mechanism for gene silencing or whether it requires repeated...... sequences such as long terminal repeats (LTRs). We analyzed the global effects of the Clr3 and Clr6 histone deacetylases, the Clr4 methyltransferase, the zinc finger protein Clr1, and the RNAi proteins Dicer, RdRP, and Argonaute on the transcriptome of Schizosaccharomyces pombe (fission yeast). The clr...... genes were repressed by both the silencing and RNAi machineries, with transcripts from centromeric repeats and Tf2 retrotransposons being notable exceptions. We found no correlation between repression by RNAi and proximity to LTRs, and the wtf family of repeated sequences seems to be repressed...

  19. Silencing of the major salt-dependent isoform of pectinesterase in tomato alters fruit softening.

    Science.gov (United States)

    Phan, Thanh D; Bo, Wen; West, Gill; Lycett, Grantley W; Tucker, Gregory A

    2007-08-01

    Pectinesterase (PE; E.C. 3.1.1.11) is an enzyme responsible for the demethylation of galacturonyl residues in high-molecular-weight pectin and is believed to play an important role in cell wall metabolism. In this study, Pmeu1, a ubiquitously expressed PE gene, has been characterized by antisense suppression in tomato (Solanum lycopersicum). Transgenic tomato plants showed reduced PE activity levels in both green fruit and leaf tissue to around 65% and 25% of that found in wild-type plants, respectively. Pmeu1 was observed to encode a salt-dependent PE isoform that correlated with PE1 as previously described in fruit tissue. Silencing of Pmeu1 did not result in any detectable phenotype within the leaf tissue despite the gene product representing the major isoform in this tissue. In comparison, silencing in fruit resulted in an enhancement to the rate of softening during ripening. The role of PMEU1 in fruit ripening is discussed.

  20. MicroRNA-Mediated Gene Silencing in Plant Defense and Viral Counter-Defense.

    Science.gov (United States)

    Liu, Sheng-Rui; Zhou, Jing-Jing; Hu, Chun-Gen; Wei, Chao-Ling; Zhang, Jin-Zhi

    2017-01-01

    MicroRNAs (miRNAs) are non-coding RNAs of approximately 20-24 nucleotides in length that serve as central regulators of eukaryotic gene expression by targeting mRNAs for cleavage or translational repression. In plants, miRNAs are associated with numerous regulatory pathways in growth and development processes, and defensive responses in plant-pathogen interactions. Recently, significant progress has been made in understanding miRNA-mediated gene silencing and how viruses counter this defense mechanism. Here, we summarize the current knowledge and recent advances in understanding the roles of miRNAs involved in the plant defense against viruses and viral counter-defense. We also document the application of miRNAs in plant antiviral defense. This review discusses the current understanding of the mechanisms of miRNA-mediated gene silencing and provides insights on the never-ending arms race between plants and viruses.

  1. Gene Silencing Triggers Polycomb Repressive Complex 2 Recruitment to CpG Islands Genome Wide

    DEFF Research Database (Denmark)

    Riising, Eva Madi; Vacher-Comet, Itys; Leblanc, Benjamin Olivier

    2014-01-01

    Polycomb group (PcG) proteins are required for normal differentiation and development and are frequently deregulated in cancer. PcG proteins are involved in gene silencing; however, their role in initiation and maintenance of transcriptional repression is not well defined. Here, we show that knoc......Polycomb group (PcG) proteins are required for normal differentiation and development and are frequently deregulated in cancer. PcG proteins are involved in gene silencing; however, their role in initiation and maintenance of transcriptional repression is not well defined. Here, we show......-wide ectopic PRC2 recruitment to endogenous PcG target genes found in other tissues. PRC2 binding analysis shows that it is restricted to nucleosome-free CpG islands (CGIs) of untranscribed genes. Our results show that it is the transcriptional state that governs PRC2 binding, and we propose that it binds...

  2. Platinum Interference with siRNA Non-seed Regions Fine-Tunes Silencing Capacity

    DEFF Research Database (Denmark)

    Hedman, Hanna K; Kirpekar, Finn; Elmroth, Sofi K C

    2011-01-01

    , cisplatin and oxaliplatin, on siRNA's silencing capacity has been evaluated. More specifically, siRNAs targeting the 3' UTR region of Wnt-5a mRNA (NM_003352) were constructed, and the biologically active antisense RNA strand was pre-platinated. Platinum adducts were detected and characterized...... by a combination of gel electrophoresis and MALDI-MS techniques, and the silencing capacity was evaluated in cellular luciferase-expressing systems using HB2 cells. Data show that platination of the antisense strand of the siRNAs results in adducts with protection against hydrolytic cleavage in the proximity...... of the platination sites, i.e., with altered degradation patterns compared to native RNAs. The MALDI-MS method was successfully used to further identify and characterize platinated RNA, with the naturally occurring platinum isotopic patterns serving as sensitive fingerprints for metalated sites. Expression assays...

  3. Bidirectional transfer of RNAi between honey bee and Varroa destructor: Varroa gene silencing reduces Varroa population.

    Science.gov (United States)

    Garbian, Yael; Maori, Eyal; Kalev, Haim; Shafir, Sharoni; Sela, Ilan

    2012-12-01

    The mite Varroa destructor is an obligatory ectoparasite of the honey bee (Apis mellifera) and is one of the major threats to apiculture worldwide. We previously reported that honey bees fed on double-stranded RNA (dsRNA) with a sequence homologous to that of the Israeli acute paralysis virus are protected from the viral disease. Here we show that dsRNA ingested by bees is transferred to the Varroa mite and from mite on to a parasitized bee. This cross-species, reciprocal exchange of dsRNA between bee and Varroa engendered targeted gene silencing in the latter, and resulted in an over 60% decrease in the mite population. Thus, transfer of gene-silencing-triggering molecules between this invertebrate host and its ectoparasite could lead to a conceptually novel approach to Varroa control.

  4. Effects of neoliberal rationality in speeches on inclusion: the teacher’s silence

    Directory of Open Access Journals (Sweden)

    Leandra Boer Possa

    2013-06-01

    Full Text Available This text, which makes use of the National Policy on Special Education in the Perspective of Inclusive Education and the programs that embrace the training of teachers for diversity/ inclusion, puts the discursive effects of these documents in analytic sets. Without attempting at doing an exhaustive analysis, this study aims at problematizing the effect of teacher’s silence that the neoliberal policy has been producing on teachers who work in municipal and state education systems in Santa Maria area. The conceptual and methodological tool of governmentality is used in this enterprise in order to think that the discourses of inclusion have convinced and subjectivized teachers, because in the face of the irreducibility of this discursive network the silence is an effect of the production and consumption of the principle of inclusion and enterprise itself.

  5. Dependence of modal attenuation coefficient frequency variation on upper sediment attenuation

    Science.gov (United States)

    Saintval, Wendy; Siegmann, William L.; Carey, William M.; Pierce, Allan D.; Lynch, James F.

    2005-04-01

    The range-averaged transmission loss increase in shallow water propagation depends critically on the intrinsic attenuation of the upper sediment. The attenuation coefficients of low-frequency (sandy-silty sediments are compared to numerical calculations, it is found that a nonlinear-frequency dependent attenuation is required with an exponent between 1.5 and 2. The question considered here is how the intrinsic upper-sediment attenuation produces such behavior. A recent simplification of the Biot model [A. D. Pierce et al., J. Acoust. Soc. Am. 114, 2345 (2003)] has a power-law exponent of two. With this frequency-dependent bottom attenuation, a two-layer Pekeris waveguide yields modal attenuation coefficients that decrease with frequency as observed by Ingenito. However, a depth-dependent attenuation profile or a third near-surface layer with requisite properties can reverse this behavior. This suggests why higher-frequency numerical computations may require nonlinear frequency-dependent sediment profiles to calculate sound transmission accurately. [Work partially supported by ONR.

  6. SETDB1 is involved in postembryonic DNA methylation and gene silencing in Drosophila.

    Directory of Open Access Journals (Sweden)

    Dawei Gou

    2010-05-01

    Full Text Available DNA methylation is fundamental for the stability and activity of genomes. Drosophila melanogaster and vertebrates establish a global DNA methylation pattern of their genome during early embryogenesis. Large-scale analyses of DNA methylation patterns have uncovered revealed that DNA methylation patterns are dynamic rather than static and change in a gene-specific fashion during development and in diseased cells. However, the factors and mechanisms involved in dynamic, postembryonic DNA methylation remain unclear. Methylation of lysine 9 in histone H3 (H3-K9 by members of the Su(var3-9 family of histone methyltransferases (HMTs triggers embryonic DNA methylation in Arthropods and Chordates. Here, we demonstrate that Drosophila SETDB1 (dSETDB1 can mediate DNA methylation and silencing of genes and retrotransposons. We found that dSETDB1 tri-methylates H3-K9 and binds methylated CpA motifs. Tri-methylation of H3-K9 by dSETDB1 mediates recruitment of DNA methyltransferase 2 (Dnmt2 and Su(var205, the Drosophila ortholog of mammalian "Heterochromatin Protein 1", to target genes for dSETDB1. By enlisting Dnmt2 and Su(var205, dSETDB1 triggers DNA methylation and silencing of genes and retrotransposons in Drosophila cells. DSETDB1 is involved in postembryonic DNA methylation and silencing of Rt1b{} retrotransposons and the tumor suppressor gene retinoblastoma family protein 1 (Rb in imaginal discs. Collectively, our findings implicate dSETDB1 in postembryonic DNA methylation, provide a model for silencing of the tumor suppressor Rb, and uncover a role for cell type-specific DNA methylation in Drosophila development.

  7. Two Chloroplastic Viroids Induce the Accumulation of Small RNAs Associated with Posttranscriptional Gene Silencing

    Science.gov (United States)

    Martínez de Alba, A. E.; Flores, R.; Hernández, C.

    2002-01-01

    In plants, posttranscriptional gene silencing (PTGS) has been reported for cytoplasmic RNAs from endogenous nuclear genes, transgenes, viruses, and, recently, for a viroid with nuclear replication and accumulation. However, phenomena of this kind have not been described for mitochondrial or chloroplastic RNAs. Here we show that viroids that replicate and accumulate in the chloroplast are also targets of PTGS and this process may control viroid titer. PMID:12438638

  8. 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.

  9. RNA Silencing in Plants: Mechanisms, Technologies and Applications in Horticultural Crops

    OpenAIRE

    Guo, Qigao; Liu, Qing; Smith, Neil A.; Liang, Guolu; Wang, Ming-Bo

    2016-01-01

    Understanding the fundamental nature of a molecular process or a biological pathway is often a catalyst for the development of new technologies in biology. Indeed, studies from late 1990s to early 2000s have uncovered multiple overlapping but functionally distinct RNA silencing pathways in plants, including the posttranscriptional microRNA and small interfering RNA pathways and the transcriptional RNA-directed DNA methylation pathway. These findings have in turn been exploited for developing ...

  10. A new component of the Nasonia sex determining cascade is maternally silenced and regulates transformer expression.

    Directory of Open Access Journals (Sweden)

    Eveline C Verhulst

    Full Text Available Although sex determination is a universal process in sexually reproducing organisms, sex determination pathways are among the most highly variable genetic systems found in nature. Nevertheless, general principles can be identified among the diversity, like the central role of transformer (tra in insects. When a functional TRA protein is produced in early embryogenesis, the female sex determining route is activated, while prevention of TRA production leads to male development. In dipterans, male development is achieved by prevention of female-specific splicing of tra mRNA, either mediated by X-chromosome dose or masculinizing factors. In Hymenoptera, which have haplodiploid sex determination, complementary sex determination and maternal imprinting have been identified to regulate timely TRA production. In the parasitoid Nasonia, zygotic transformer (Nvtra expression and splicing is regulated by a combination of maternal provision of Nvtra mRNA and silencing of Nvtra expression in unfertilized eggs. It is unclear, however, if this silencing is directly on the tra locus or whether it is mediated through maternal silencing of a trans-acting factor. Here we show that in Nasonia, female sex determination is dependent on zygotic activation of Nvtra expression by an as yet unknown factor. This factor, which we propose to term womanizer (wom, is maternally silenced during oogenesis to ensure male development in unfertilized eggs. This finding implicates the upstream recruitment of a novel gene in the Nasonia sex determining cascade and supports the notion that sex determining cascades can rapidly change by adding new components on top of existing regulators.

  11. Synthetic versions of firefly luciferase and Renilla luciferase reporter genes that resist transgene silencing in sugarcane

    Science.gov (United States)

    2014-01-01

    Background Down-regulation or silencing of transgene expression can be a major hurdle to both molecular studies and biotechnology applications in many plant species. Sugarcane is particularly effective at silencing introduced transgenes, including reporter genes such as the firefly luciferase gene. Synthesizing transgene coding sequences optimized for usage in the host plant is one method of enhancing transgene expression and stability. Using specified design rules we have synthesised new coding sequences for both the firefly luciferase and Renilla luciferase reporter genes. We have tested these optimized versions for enhanced levels of luciferase activity and for increased steady state luciferase mRNA levels in sugarcane. Results The synthetic firefly luciferase (luc*) and Renilla luciferase (Renluc*) coding sequences have elevated G + C contents in line with sugarcane codon usage, but maintain 75% identity to the native firefly or Renilla luciferase nucleotide sequences and 100% identity to the protein coding sequences. Under the control of the maize pUbi promoter, the synthetic luc* and Renluc* genes yielded 60x and 15x higher luciferase activity respectively, over the native firefly and Renilla luciferase genes in transient assays on sugarcane suspension cell cultures. Using a novel transient assay in sugarcane suspension cells combining co-bombardment and qRT-PCR, we showed that synthetic luc* and Renluc* genes generate increased transcript levels compared to the native firefly and Renilla luciferase genes. In stable transgenic lines, the luc* transgene generated significantly higher levels of expression than the native firefly luciferase transgene. The fold difference in expression was highest in the youngest tissues. Conclusions We developed synthetic versions of both the firefly and Renilla luciferase reporter genes that resist transgene silencing in sugarcane. These transgenes will be particularly useful for evaluating the expression patterns conferred

  12. The trans-silencing capacity of invertedly repeated transgenes depends on their epigenetic state in tobacco

    Czech Academy of Sciences Publication Activity Database

    Fojtová, Miloslava; Bleys, A.; Bedřichová, Jana; Van Houdt, H.; Křížová, Kateřina; Depicker, A.; Kovařík, Aleš

    2006-01-01

    Roč. 34, č. 8 (2006), s. 2280-2293 ISSN 0305-1048 R&D Projects: GA ČR(CZ) GA521/04/0775; GA ČR(CZ) GD204/05/H505 Institutional research plan: CEZ:AV0Z50040507 Keywords : transgenes * epigenetic silencing * DNA methylation Subject RIV: BO - Biophysics Impact factor: 6.317, year: 2006

  13. A New Component of the Nasonia Sex Determining Cascade Is Maternally Silenced and Regulates Transformer Expression

    Science.gov (United States)

    Bopp, Daniel; Beukeboom, Leo W.; van de Zande, Louis

    2013-01-01

    Although sex determination is a universal process in sexually reproducing organisms, sex determination pathways are among the most highly variable genetic systems found in nature. Nevertheless, general principles can be identified among the diversity, like the central role of transformer (tra) in insects. When a functional TRA protein is produced in early embryogenesis, the female sex determining route is activated, while prevention of TRA production leads to male development. In dipterans, male development is achieved by prevention of female-specific splicing of tra mRNA, either mediated by X-chromosome dose or masculinizing factors. In Hymenoptera, which have haplodiploid sex determination, complementary sex determination and maternal imprinting have been identified to regulate timely TRA production. In the parasitoid Nasonia, zygotic transformer (Nvtra) expression and splicing is regulated by a combination of maternal provision of Nvtra mRNA and silencing of Nvtra expression in unfertilized eggs. It is unclear, however, if this silencing is directly on the tra locus or whether it is mediated through maternal silencing of a trans-acting factor. Here we show that in Nasonia, female sex determination is dependent on zygotic activation of Nvtra expression by an as yet unknown factor. This factor, which we propose to term womanizer (wom), is maternally silenced during oogenesis to ensure male development in unfertilized eggs. This finding implicates the upstream recruitment of a novel gene in the Nasonia sex determining cascade and supports the notion that sex determining cascades can rapidly change by adding new components on top of existing regulators. PMID:23717455

  14. Post-translational selective intracellular silencing of acetylated proteins with de novo selected intrabodies.

    Science.gov (United States)

    Chirichella, Michele; Lisi, Simonetta; Fantini, Marco; Goracci, Martina; Calvello, Mariantonietta; Brandi, Rossella; Arisi, Ivan; D'Onofrio, Mara; Di Primio, Cristina; Cattaneo, Antonino

    2017-03-01

    The ability to selectively interfere with post-translationally modified proteins would have many biological and therapeutic applications. However, post-translational modifications cannot be selectively targeted by nucleic-acid-based interference approaches. Here we describe post-translational intracellular silencing antibody technology (PISA), a method for selecting intrabodies against post-translationally modified proteins. We demonstrate our method by generating intrabodies against native acetylated proteins and showing functional interference in living cells.

  15. MicroRNA-Mediated Gene Silencing in Plant Defense and Viral Counter-Defense

    OpenAIRE

    Liu, Sheng-Rui; Zhou, Jing-Jing; Hu, Chun-Gen; Wei, Chao-Ling; Zhang, Jin-Zhi

    2017-01-01

    MicroRNAs (miRNAs) are non-coding RNAs of approximately 20–24 nucleotides in length that serve as central regulators of eukaryotic gene expression by targeting mRNAs for cleavage or translational repression. In plants, miRNAs are associated with numerous regulatory pathways in growth and development processes, and defensive responses in plant–pathogen interactions. Recently, significant progress has been made in understanding miRNA-mediated gene silencing and how viruses counter this defense ...

  16. FXR silencing in human colon cancer by DNA methylation and KRAS signaling.

    Science.gov (United States)

    Bailey, Ann M; Zhan, Le; Maru, Dipen; Shureiqi, Imad; Pickering, Curtis R; Kiriakova, Galina; Izzo, Julie; He, Nan; Wei, Caimiao; Baladandayuthapani, Veerabhadran; Liang, Han; Kopetz, Scott; Powis, Garth; Guo, Grace L

    2014-01-01

    Farnesoid X receptor (FXR) is a bile acid nuclear receptor described through mouse knockout studies as a tumor suppressor for the development of colon adenocarcinomas. This study investigates the regulation of FXR in the development of human colon cancer. We used immunohistochemistry of FXR in normal tissue (n = 238), polyps (n = 32), and adenocarcinomas, staged I-IV (n = 43, 39, 68, and 9), of the colon; RT-quantitative PCR, reverse-phase protein array, and Western blot analysis in 15 colon cancer cell lines; NR1H4 promoter methylation and mRNA expression in colon cancer samples from The Cancer Genome Atlas; DNA methyltransferase inhibition; methyl-DNA immunoprecipitation (MeDIP); bisulfite sequencing; and V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) knockdown assessment to investigate FXR regulation in colon cancer development. Immunohistochemistry and quantitative RT-PCR revealed that expression and function of FXR was reduced in precancerous lesions and silenced in a majority of stage I-IV tumors. FXR expression negatively correlated with phosphatidylinositol-4, 5-bisphosphate 3 kinase signaling and the epithelial-to-mesenchymal transition. The NR1H4 promoter is methylated in ~12% colon cancer The Cancer Genome Atlas samples, and methylation patterns segregate with tumor subtypes. Inhibition of DNA methylation and KRAS silencing both increased FXR expression. FXR expression is decreased early in human colon cancer progression, and both DNA methylation and KRAS signaling may be contributing factors to FXR silencing. FXR potentially suppresses epithelial-to-mesenchymal transition and other oncogenic signaling cascades, and restoration of FXR activity, by blocking silencing mechanisms or increasing residual FXR activity, represents promising therapeutic options for the treatment of colon cancer.

  17. Agrobacterium mediated transient gene silencing (AMTS in Stevia rebaudiana: insights into steviol glycoside biosynthesis pathway.

    Directory of Open Access Journals (Sweden)

    Praveen Guleria

    Full Text Available Steviol glycoside biosynthesis pathway has emerged as bifurcation from ent-kaurenoic acid, substrate of methyl erythritol phosphate pathway that also leads to gibberellin biosynthesis. However, the genetic regulation of steviol glycoside biosynthesis has not been studied. So, in present study RNA interference (RNAi based Agrobacterium mediated transient gene silencing (AMTS approach was followed. SrKA13H and three SrUGTs (SrUGT85C2, SrUGT74G1 and SrUGT76G1 genes encoding ent-kaurenoic acid-13 hydroxylase and three UDP glycosyltransferases of steviol glycoside biosynthesis pathway were silenced in Stevia rebaudiana to understand its molecular mechanism and association with gibberellins.RNAi mediated AMTS of SrKA13H and three SrUGTs has significantly reduced the expression of targeted endogenous genes as well as total steviol glycoside accumulation. While gibberellins (GA3 content was significantly enhanced on AMTS of SrUGT85C2 and SrKA13H. Silencing of SrKA13H and SrUGT85C2 was found to block the metabolite flux of steviol glycoside pathway and shifted it towards GA3 biosynthesis. Further, molecular docking of three SrUGT proteins has documented highest affinity of SrUGT76G1 for the substrates of alternate pathways synthesizing steviol glycosides. This could be a plausible reason for maximum reduction in steviol glycoside content on silencing of SrUGT76G1 than other genes.SrKA13H and SrUGT85C2 were identified as regulatory genes influencing carbon flux between steviol glycoside and gibberellin biosynthesis. This study has also documented the existence of alternate steviol glycoside biosynthesis route.

  18. Agrobacterium Mediated Transient Gene Silencing (AMTS) in Stevia rebaudiana: Insights into Steviol Glycoside Biosynthesis Pathway

    Science.gov (United States)

    Guleria, Praveen; Yadav, Sudesh Kumar

    2013-01-01

    Background Steviol glycoside biosynthesis pathway has emerged as bifurcation from ent-kaurenoic acid, substrate of methyl erythritol phosphate pathway that also leads to gibberellin biosynthesis. However, the genetic regulation of steviol glycoside biosynthesis has not been studied. So, in present study RNA interference (RNAi) based Agrobacterium mediated transient gene silencing (AMTS) approach was followed. SrKA13H and three SrUGTs (SrUGT85C2, SrUGT74G1 and SrUGT76G1) genes encoding ent-kaurenoic acid-13 hydroxylase and three UDP glycosyltransferases of steviol glycoside biosynthesis pathway were silenced in Stevia rebaudiana to understand its molecular mechanism and association with gibberellins. Methodology/Principal Findings RNAi mediated AMTS of SrKA13H and three SrUGTs has significantly reduced the expression of targeted endogenous genes as well as total steviol glycoside accumulation. While gibberellins (GA3) content was significantly enhanced on AMTS of SrUGT85C2 and SrKA13H. Silencing of SrKA13H and SrUGT85C2 was found to block the metabolite flux of steviol glycoside pathway and shifted it towards GA3 biosynthesis. Further, molecular docking of three SrUGT proteins has documented highest affinity of SrUGT76G1 for the substrates of alternate pathways synthesizing steviol glycosides. This could be a plausible reason for maximum reduction in steviol glycoside content on silencing of SrUGT76G1 than other genes. Conclusions SrKA13H and SrUGT85C2 were identified as regulatory genes influencing carbon flux between steviol glycoside and gibberellin biosynthesis. This study has also documented the existence of alternate steviol glycoside biosynthesis route. PMID:24023961

  19. Sde2: A novel nuclear protein essential for telomeric silencing and genomic stability in Schizosaccharomyces pombe

    International Nuclear Information System (INIS)

    Sugioka-Sugiyama, Rie; Sugiyama, Tomoyasu

    2011-01-01

    Research highlights: → Sde2 is essential for telomere silencing. → Sde2 is involved in the maintenance of genomic stability. → Sde2 promotes the recruitment of SHREC, a histone deacetylase complex, to telomeres. -- Abstract: Telomeres, specialized domains assembled at the ends of linear chromosomes, are essential for genomic stability in eukaryotes. The formation and maintenance of telomeres are governed by numerous factors such as telomeric repeats, telomere-binding proteins, heterochromatin proteins, and telomerase. Here, we report Sde2, a novel nuclear protein essential for telomeric silencing and genomic stability in the fission yeast Schizosaccharomyces pombe. A deficiency in sde2 results in the derepression of the ura4 + gene inserted near telomeric repeats, and the noncoding transcripts from telomeric regions accumulate in sde2Δ cells. The loss of Sde2 function compromises transcriptional silencing at telomeres, and this silencing defect is accompanied by increased levels of acetylated histone H3K14 and RNA polymerase II occupancy at telomeres as well as reduced recruitment of the SNF2 ATPase/histone deacetylase-containing complex SHREC to telomeres. Deletion of sde2 also leads to a higher frequency of mitotic minichromosome loss, and sde2Δ cells often form asci that contain spores in abnormal numbers, shapes, or both. In addition, sde2Δ cells are highly sensitive to several stresses, including high/low temperatures, bleomycin, which induces DNA damage, and thiabendazole, a microtubule-destabilizing agent. Furthermore, Sde2 genetically interacts with the telomere regulators Taz1, Pof3, and Ccq1. These findings demonstrate that Sde2 cooperates with other telomere regulators to maintain functional telomeres, thereby preventing genomic instability.

  20. Silencing Dkk1 expression rescues dexamethasone-induced suppression of primary human osteoblast differentiation.

    LENUS (Irish Health Repository)

    Butler, Joseph S

    2010-09-01

    The Wnt\\/β-catenin pathway is a major signaling cascade in bone biology, playing a key role in bone development and remodeling. The objectives of this study were firstly, to determine the effects of dexamethasone exposure on Wnt\\/β-catenin signaling at an intracellular and transcriptional level, and secondly, to assess the phenotypic effects of silencing the Wnt antagonist, Dickkopf-1 (Dkk1) in the setting of dexamethasone exposure.

  1. Bone marrow mesenchymal stem cells with Nogo-66 receptor gene silencing for repair of spinal cord injury.

    Science.gov (United States)

    Li, Zhiyuan; Zhang, Zhanxiu; Zhao, Lili; Li, Hui; Wang, Suxia; Shen, Yong

    2014-04-15

    We hypothesized that RNA interference to silence Nogo-66 receptor gene expression in bone marrow mesenchymal stem cells before transplantation might further improve neurological function in rats with spinal cord transection injury. After 2 weeks, the number of neurons and BrdU-positive cells in the Nogo-66 receptor gene silencing group was higher than in the bone marrow mesenchymal stem cell group, and significantly greater compared with the model group. After 4 weeks, behavioral performance was significantly enhanced in the model group. After 8 weeks, the number of horseradish peroxidase-labeled nerve fibers was higher in the Nogo-66 receptor gene silencing group than in the bone marrow mesenchymal stem cell group, and significantly higher than in the model group. The newly formed nerve fibers and myelinated nerve fibers were detectable in the central transverse plane section in the bone marrow mesenchymal stem cell group and in the Nogo-66 receptor gene silencing group.

  2. Bone marrow mesenchymal stem cells with Nogo-66 receptor gene silencing for repair of spinal cord injury

    Science.gov (United States)

    Li, Zhiyuan; Zhang, Zhanxiu; Zhao, Lili; Li, Hui; Wang, Suxia; Shen, Yong

    2014-01-01

    We hypothesized that RNA interference to silence Nogo-66 receptor gene expression in bone marrow mesenchymal stem cells before transplantation might further improve neurological function in rats with spinal cord transection injury. After 2 weeks, the number of neurons and BrdU-positive cells in the Nogo-66 receptor gene silencing group was higher than in the bone marrow mesenchymal stem cell group, and significantly greater compared with the model group. After 4 weeks, behavioral performance was significantly enhanced in the model group. After 8 weeks, the number of horseradish peroxidase-labeled nerve fibers was higher in the Nogo-66 receptor gene silencing group than in the bone marrow mesenchymal stem cell group, and significantly higher than in the model group. The newly formed nerve fibers and myelinated nerve fibers were detectable in the central transverse plane section in the bone marrow mesenchymal stem cell group and in the Nogo-66 receptor gene silencing group. PMID:25206893

  3. Genetic transformation and gene silencing mediated by multiple copies of a transgene in eastern white pine.

    Science.gov (United States)

    Tang, Wei; Newton, Ronald J; Weidner, Douglas A

    2007-01-01

    An efficient transgenic eastern white pine (Pinus strobus L.) plant regeneration system has been established using Agrobacterium tumefaciens strain GV3850-mediated transformation and the green fluorescent protein (gfp) gene as a reporter in this investigation. Stable integration of transgenes in the plant genome of pine was confirmed by polymerase chain reaction (PCR), Southern blot, and northern blot analyses. Transgene expression was analysed in pine T-DNA transformants carrying different numbers of copies of T-DNA insertions. Post-transcriptional gene silencing (PTGS) was mostly obtained in transgenic lines with more than three copies of T-DNA, but not in transgenic lines with one copy of T-DNA. In situ hybridization chromosome analysis of transgenic lines demonstrated that silenced transgenic lines had two or more T-DNA insertions in the same chromosome. These results suggest that two or more T-DNA insertions in the same chromosome facilitate efficient gene silencing in transgenic pine cells expressing green fluorescent protein. There were no differences in shoot differentiation and development between transgenic lines with multiple T-DNA copies and transgenic lines with one or two T-DNA copies.

  4. Silencing of the Il2 gene transcription is regulated by epigenetic changes in anergic T cells.

    Science.gov (United States)

    Bandyopadhyay, Sanmay; Montagna, Cristina; Macian, Fernando

    2012-09-01

    Anergy is induced in T cells as a consequence of a partial or suboptimal stimulation. Anergic T cells become unresponsive and fail to proliferate and produce cytokines. We had previously shown that in anergic CD4(+) T cells, Ikaros participates in the transcriptional repression of the Il2 gene by recruiting histone deacetylases that cause core histone deacetylation at the Il2 promoter. Here we show that deacetylation at the Il2 promoter is the initial step in a process that leads to the stable silencing of the Il2 gene transcription in anergic T cells. We have found that anergy-induced deacetylation of the Il2 promoter permits binding of the histone methyl-transferase Suv39H1, which trimethylates lysine-9 of histone H3 (Me3H3-K9). Furthermore, the establishment of the Me3H3-K9 mark allows the recruitment of the heterochromatin protein HP1, allowing the silenced Il2 loci to reposition close to heterochromatin-rich regions. Our results indicate that silencing of Il2 transcription in anergic T cells is attained through a series of epigenetic changes that involve the establishment of repressive marks and the subsequent nuclear repositioning of the Il2 loci, which become juxtaposed to transcriptionally silent regions. This mechanism may account for the stable nature of the inhibition of IL-2 production in anergic cells. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. The C. elegans CSR-1 argonaute pathway counteracts epigenetic silencing to promote germline gene expression.

    Science.gov (United States)

    Seth, Meetu; Shirayama, Masaki; Gu, Weifeng; Ishidate, Takao; Conte, Darryl; Mello, Craig C

    2013-12-23

    Organisms can develop adaptive sequence-specific immunity by reexpressing pathogen-specific small RNAs that guide gene silencing. For example, the C. elegans PIWI-Argonaute/piwi-interacting RNA (piRNA) pathway recruits RNA-dependent RNA polymerase (RdRP) to foreign sequences to amplify a transgenerational small-RNA-induced epigenetic silencing signal (termed RNAe). Here, we provide evidence that, in addition to an adaptive memory of silenced sequences, C. elegans can also develop an opposing adaptive memory of expressed/self-mRNAs. We refer to this mechanism, which can prevent or reverse RNAe, as RNA-induced epigenetic gene activation (RNAa). We show that CSR-1, which engages RdRP-amplified small RNAs complementary to germline-expressed mRNAs, is required for RNAa. We show that a transgene with RNAa activity also exhibits accumulation of cognate CSR-1 small RNAs. Our findings suggest that C. elegans adaptively acquires and maintains a transgenerational CSR-1 memory that recognizes and protects self-mRNAs, allowing piRNAs to recognize foreign sequences innately, without the need for prior exposure

  6. Silence is golden : keeping a lid on noise quiets opposition to oilpatch operations

    International Nuclear Information System (INIS)

    Macedo, R.

    2006-01-01

    Record levels of drilling activity have led to denser well spacings that are often close to residential areas. Many oil and gas operators are now investing in noise suppression technology in order to suppress public concern over noise levels. This article reviewed some new silencing technologies available to the oil and gas industry. Issues concerning permissible sound levels for remote facilities were discussed. Silencing equipment details were presented for turbine exhaust engines, turbo inlet systems, reciprocating engines, and specialty silencers for ventilation systems. Issues concerning acoustical systems and retrofits for existing buildings were also examined. It was noted that a new muffler has been acoustically engineered to provide engine exhaust noise removal along with an internal acoustic treatment to eliminate radiated noise from the muffler shell. The loudest noise source at a compression station is often the engine exhaust of large reciprocating engines. Various computer programs are now available that analyze noise, create models to predict noise levels in decibels for nearby residents, and help to engineer noise control plans. It was concluded that many of the new sound-proofing technologies for the walls and roofs of buildings and enclosures were developed during the design of new compression units built by TransCanada Pipeline on main pipelines across Canada. 2 figs

  7. A Foxtail mosaic virus Vector for Virus-Induced Gene Silencing in Maize1[OPEN

    Science.gov (United States)

    Mei, Yu; Kernodle, Bliss M.; Hill, John H.

    2016-01-01

    Plant viruses have been widely used as vectors for foreign gene expression and virus-induced gene silencing (VIGS). A limited number of viruses have been developed into viral vectors for the purposes of gene expression or VIGS in monocotyledonous plants, and among these, the tripartite viruses Brome mosaic virus and Cucumber mosaic virus have been shown to induce VIGS in maize (Zea mays). We describe here a new DNA-based VIGS system derived from Foxtail mosaic virus (FoMV), a monopartite virus that is able to establish systemic infection and silencing of endogenous maize genes homologous to gene fragments inserted into the FoMV genome. To demonstrate VIGS applications of this FoMV vector system, four genes, phytoene desaturase (functions in carotenoid biosynthesis), lesion mimic22 (encodes a key enzyme of the porphyrin pathway), iojap (functions in plastid development), and brown midrib3 (caffeic acid O-methyltransferase), were silenced and characterized in the sweet corn line Golden × Bantam. Furthermore, we demonstrate that the FoMV infectious clone establishes systemic infection in maize inbred lines, sorghum (Sorghum bicolor), and green foxtail (Setaria viridis), indicating the potential wide applications of this viral vector system for functional genomics studies in maize and other monocots. PMID:27208311

  8. A Foxtail mosaic virus Vector for Virus-Induced Gene Silencing in Maize.

    Science.gov (United States)

    Mei, Yu; Zhang, Chunquan; Kernodle, Bliss M; Hill, John H; Whitham, Steven A

    2016-06-01

    Plant viruses have been widely used as vectors for foreign gene expression and virus-induced gene silencing (VIGS). A limited number of viruses have been developed into viral vectors for the purposes of gene expression or VIGS in monocotyledonous plants, and among these, the tripartite viruses Brome mosaic virus and Cucumber mosaic virus have been shown to induce VIGS in maize (Zea mays). We describe here a new DNA-based VIGS system derived from Foxtail mosaic virus (FoMV), a monopartite virus that is able to establish systemic infection and silencing of endogenous maize genes homologous to gene fragments inserted into the FoMV genome. To demonstrate VIGS applications of this FoMV vector system, four genes, phytoene desaturase (functions in carotenoid biosynthesis), lesion mimic22 (encodes a key enzyme of the porphyrin pathway), iojap (functions in plastid development), and brown midrib3 (caffeic acid O-methyltransferase), were silenced and characterized in the sweet corn line Golden × Bantam. Furthermore, we demonstrate that the FoMV infectious clone establishes systemic infection in maize inbred lines, sorghum (Sorghum bicolor), and green foxtail (Setaria viridis), indicating the potential wide applications of this viral vector system for functional genomics studies in maize and other monocots. © 2016 American Society of Plant Biologists. All Rights Reserved.

  9. Use of a Virus Gene Silencing Vector for Maize Functional Genomics Research.

    Science.gov (United States)

    Zhou, Tao; Liu, Xuedong; Fan, Zaifeng

    2018-01-01

    Virus-induced gene silencing (VIGS) is a genetic technology that exploits the RNA-mediated defense against virus. The method has great potential for plant reverse genetics as it could knock down gene expression in a rapid way, which is triggered by a replicating viral genome engineered to carry a fragment of host gene to be silenced. A number of efficient VIGS vectors are available for dicots, such as for model plant Nicotiana benthamiana; however, only a few of VIGS vectors for monocotyledonous cereal crops. Here, we describe the method for the use of a newly developed VIGS vector based on a maize-infecting Cucumber mosaic virus (CMV) strain ZMBJ-CMV for maize. The RNA2 of ZMBJ-CMV was modified as a vector pCMV201-2b N81 having multiple cloning sites for the insert of 100-300 bp fragment of target gene. Using a method of vascular puncture inoculation of maize seeds with crude sap prepared from Agrobacterium-infiltrated N. benthamiana leaves, silencing of target genes could be obtained in 4 weeks.

  10. A comparison between analytic and numerical methods for modelling automotive dissipative silencers with mean flow

    Science.gov (United States)

    Kirby, R.

    2009-08-01

    Identifying an appropriate method for modelling automotive dissipative silencers normally requires one to choose between analytic and numerical methods. It is common in the literature to justify the choice of an analytic method based on the assumption that equivalent numerical techniques are more computationally expensive. The validity of this assumption is investigated here, and the relative speed and accuracy of two analytic methods are compared to two numerical methods for a uniform dissipative silencer that contains a bulk reacting porous material separated from a mean gas flow by a perforated pipe. The numerical methods are developed here with a view to speeding up transmission loss computation, and are based on a mode matching scheme and a hybrid finite element method. The results presented demonstrate excellent agreement between the analytic and numerical models provided a sufficient number of propagating acoustic modes are retained. However, the numerical mode matching method is shown to be the fastest method, significantly outperforming an equivalent analytic technique. Moreover, the hybrid finite element method is demonstrated to be as fast as the analytic technique. Accordingly, both numerical techniques deliver fast and accurate predictions and are capable of outperforming equivalent analytic methods for automotive dissipative silencers.

  11. On the Threshold: Time and the Speaking Subject in Harold Pinter’s Silence

    Directory of Open Access Journals (Sweden)

    Beatrice Nori

    2017-07-01

    Full Text Available The article investigates Harold Pinter’s play Silence from a linguistic and phenomenological point of view. Silence is probably one of the least studied – though one of the most difficult and compelling – of Pinter’s plays. The author iden­tifies the broken syntax and the combi­nation of utterances and silences as indicators of time and space shifts. She claims that the patchwork which appears from the structure of the play depicts the loss of logic, and that the abandonmen­t of chronological time in linguistic terms conveys the subjecti­ve, circular, and illogical elemen­t of the human experience of time. Characters’ bodies and utterances materialize both their own past recollections and their presen­t experiences. The presen­t work may be useful to theatre scholars as an example of drama as a portrayal of philosophical and linguistic theories about time and discourse.

  12. Biochemical and genetic functional dissection of the P38 viral suppressor of RNA silencing.

    Science.gov (United States)

    Iki, Taichiro; Tschopp, Marie-Aude; Voinnet, Olivier

    2017-05-01

    Phytoviruses encode viral suppressors of RNA silencing (VSRs) to counteract the plant antiviral silencing response, which relies on virus-derived small interfering (si)RNAs processed by Dicer RNaseIII enzymes and subsequently loaded into ARGONAUTE (AGO) effector proteins. Here, a tobacco cell-free system was engineered to recapitulate the key steps of antiviral RNA silencing and, in particular, the most upstream double-stranded (ds)RNA processing reaction, not kinetically investigated thus far in the context of plant VSR studies. Comparative biochemical analyses of distinct VSRs in the reconstituted assay showed that in all cases tested, VSR interactions with siRNA duplexes inhibited the loading, but not the activity, of antiviral AGO1 and AGO2. Turnip crinkle virus P38 displayed the additional and unique property to bind both synthetic and RNA-dependent-RNA-polymerase-generated long dsRNAs, and inhibited the processing into siRNAs. Single amino acid substitutions in P38 could dissociate dsRNA-processing from AGO-loading inhibition in vitro and in vivo, illustrating dual-inhibitory strategies discriminatively deployed within a single viral protein, which, we further show, are bona fide suppressor functions that evolved independently of the conserved coat protein function of P38. © 2017 Iki et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  13. Silence and Memories of War: An Autoethnographic Exploration of Family Secrecy.

    Science.gov (United States)

    Rober, Peter; Rosenblatt, Paul C

    2017-03-01

    A personal journey and a scientific challenge, this is an autoethnographic study about my own family's secrecy. I knew my grandfather had been a German prisoner of war during World War II. We all knew. But nobody talked about it. Then one day I decided I wanted to do systematic research on the issue of family secrecy around my grandfather's war experiences. Researching one's own family can be called autoethnography. It could be said that autoethnography is an approach to research that aims to describe and systemically analyze (graphy) personal experience (auto) to understand social and cultural phenomena (ethno). This scientific approach is quite new in the field of family therapy. This study has been an important personal quest, but it also led to important reflections on silences in families, on my own professional development, and on methodological issues concerning autoethnographical research. For one thing, it highlights some of the positive aspects of family secrecy and silences, and invites us-when confronted with family secrecy in clinical practice-to carefully consider the potential destructive and life-giving aspects of the silence. © 2015 Family Process Institute.

  14. HIGS: host-induced gene silencing in the obligate biotrophic fungal pathogen Blumeria graminis.

    Science.gov (United States)

    Nowara, Daniela; Gay, Alexandra; Lacomme, Christophe; Shaw, Jane; Ridout, Christopher; Douchkov, Dimitar; Hensel, Götz; Kumlehn, Jochen; Schweizer, Patrick

    2010-09-01

    Powdery mildew fungi are obligate biotrophic pathogens that only grow on living hosts and cause damage in thousands of plant species. Despite their agronomical importance, little direct functional evidence for genes of pathogenicity and virulence is currently available because mutagenesis and transformation protocols are lacking. Here, we show that the accumulation in barley (Hordeum vulgare) and wheat (Triticum aestivum) of double-stranded or antisense RNA targeting fungal transcripts affects the development of the powdery mildew fungus Blumeria graminis. Proof of concept for host-induced gene silencing was obtained by silencing the effector gene Avra10, which resulted in reduced fungal development in the absence, but not in the presence, of the matching resistance gene Mla10. The fungus could be rescued from the silencing of Avra10 by the transient expression of a synthetic gene that was resistant to RNA interference (RNAi) due to silent point mutations. The results suggest traffic of RNA molecules from host plants into B. graminis and may lead to an RNAi-based crop protection strategy against fungal pathogens.

  15. Epigenetic silencing of host cell defense genes enhances intracellular survival of the rickettsial pathogen Anaplasma phagocytophilum.

    Directory of Open Access Journals (Sweden)

    Jose C Garcia-Garcia

    2009-06-01

    Full Text Available Intracellular bacteria have evolved mechanisms that promote survival within hostile host environments, often resulting in functional dysregulation and disease. Using the Anaplasma phagocytophilum-infected granulocyte model, we establish a link between host chromatin modifications, defense gene transcription and intracellular bacterial infection. Infection of THP-1 cells with A. phagocytophilum led to silencing of host defense gene expression. Histone deacetylase 1 (HDAC1 expression, activity and binding to the defense gene promoters significantly increased during infection, which resulted in decreased histone H3 acetylation in infected cells. HDAC1 overexpression enhanced infection, whereas pharmacologic and siRNA HDAC1 inhibition significantly decreased bacterial load. HDAC2 does not seem to be involved, since HDAC2 silencing by siRNA had no effect on A. phagocytophilum intracellular propagation. These data indicate that HDAC up-regulation and epigenetic silencing of host cell defense genes is required for A. phagocytophilum infection. Bacterial epigenetic regulation of host cell gene transcription could be a general mechanism that enhances intracellular pathogen survival while altering cell function and promoting disease.

  16. 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.

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

    Directory of Open Access Journals (Sweden)

    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.

  18. 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.

  19. RASSF10 is epigenetically silenced and functions as a tumor suppressor in gastric cancer

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Ziran [Department of General Surgery, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai (China); Chen, Xia [Urology Department, Minhang District Central Hospital, Shanghai (China); Chen, Ji; Wang, Weimin [Department of General Surgery, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai (China); Xu, Xudong [Urology Department, Minhang District Central Hospital, Shanghai (China); Cai, Qingping, E-mail: qingping_caicz@163.com [Department of General Surgery, Shanghai Changzheng Hospital, Second Military Medical University, Shanghai (China)

    2013-03-22

    Highlights: ► Epigenetic silencing of RASSF10 gene expression in GC cells. ► RASSF10 overexpression inhibits cell growth in vitro and in vivo. ► RASSF10 induces apoptosis in GC cells. ► RASSF10 inhibits Wnt/β-catenin signaling pathway. -- Abstract: Ras association domain family (RASSF) proteins are encoded by several tumor suppressor genes that are frequently silenced in human cancers. In this study, we investigated RASSF10 as a target of epigenetic inactivation and examined its functions as a tumor suppressor in gastric cancer. RASSF10 was silenced in six out of eight gastric cancer cell lines. Loss or downregulation of RASSF10 expression was associated with promoter hypermethylation, and could be restored by a demethylating agent. Overexpression of RASSF10 in gastric cancer cell lines (JRST, BGC823) suppressed cell growth and colony formation, and induced apoptosis, whereas RASSF10 depletion promoted cell growth. In xenograft animal experiments, RASSF10 overexpression effectively repressed tumor growth. Mechanistic investigations revealed that RASSF10 inhibited tumor growth by blocking activation of β-catenin and its downstream targets including c-Myc, cyclinD1, cyclinE1, peroxisome proliferator-activated receptor δ, transcription factor 4, transcription factor 1 and CD44. In conclusion, the results of this study provide insight into the role of RASSF10 as a novel functional tumor suppressor in gastric cancer through inhibition of the Wnt/β-catenin signaling pathway.

  20. Paul Leni’s Waxworks: Writing Images from Silence, through Media and Philosophy

    Directory of Open Access Journals (Sweden)

    Marcondes Ciro Inácio

    2016-12-01

    Full Text Available The so-called German Weimar Cinema encompasses a profusion of films that used frame narratives. In the case of Paul Leni’s Waxworks (Das Wachsfigurenkabinett, 1924, as the framing stems from a literary act (the stories are framed by the act of narration, the film proposes the mise-en-abyme technique as a sort of immersion into the intermedial when it deals with notions like speaking, writing, silence, image and cinema. In the case of silent cinema, and especially in Waxworks, the presence of a perverse relation with the medium of writing becomes noticeable (producing a fantasy of writing, since every effort to represent the literary act on film results in an infinite production of silent images, creating a parody effect and even postulating an act of aggression against writing. This confrontational relation between the writing code and the code of the mute image in silent cinema allows us to suggest that there is an inherent inflexibility in the language of silent cinema which does not allow the coexistence of written and spoken word as complementary codes. On the contrary, in silent cinema, the image and the silence of the film seem to work against the word, the spoken word being set forth against silence, and the written word against images.

  1. The fungus Neurospora crassa displays telomeric silencing mediated by multiple sirtuins and by methylation of histone H3 lysine 9

    Directory of Open Access Journals (Sweden)

    Smith Kristina M

    2008-11-01

    Full Text Available Abstract Background Silencing of genes inserted near telomeres provides a model to investigate the function of heterochromatin. We initiated a study of telomeric silencing in Neurospora crassa, a fungus that sports DNA methylation, unlike most other organisms in which telomeric silencing has been characterized. Results The selectable marker, hph, was inserted at the subtelomere of Linkage Group VR in an nst-1 (neurospora sir two-1 mutant and was silenced when nst-1 function was restored. We show that NST-1 is an H4-specific histone deacetylase. A second marker, bar, tested at two other subtelomeres, was similarly sensitive to nst-1 function. Mutation of three additional SIR2 homologues, nst-2, nst-3 and nst-5, partially relieved silencing. Two genes showed stronger effects: dim-5, which encodes a histone H3 K9 methyltransferase and hpo, which encodes heterochromatin protein-1. Subtelomeres showed variable, but generally low, levels of DNA methylation. Elimination of DNA methylation caused partial derepression of one telomeric marker. Characterization of histone modifications at subtelomeric regions revealed H3 trimethyl-K9, H3 trimethyl-K27, and H4 trimethyl-K20 enrichment. These modifications were slightly reduced when telomeric silencing was compromised. In contrast, acetylation of histones H3 and H4 increased. Conclusion We demonstrate the presence of telomeric silencing in Neurospora and show a dependence on histone deacetylases and methylation of histone H3 lysine 9. Our studies also reveal silencing functions for DIM-5 and HP1 that appear independent of their role in de novo DNA methylation.

  2. Silencing of DND1 in potato and tomato impedes conidial germination, attachment and hyphal growth of Botrytis cinerea.

    Science.gov (United States)

    Sun, Kaile; van Tuinen, Ageeth; van Kan, Jan A L; Wolters, Anne-Marie A; Jacobsen, Evert; Visser, Richard G F; Bai, Yuling

    2017-12-06

    Botrytis cinerea, a necrotrophic pathogenic fungus, attacks many crops including potato and tomato. Major genes for complete resistance to B. cinerea are not known in plants, but a few quantitative trait loci have been described in tomato. Loss of function of particular susceptibility (S) genes appears to provide a new source of resistance to B. cinerea in Arabidopsis. In this study, orthologs of Arabidopsis S genes (DND1, DMR6, DMR1 and PMR4) were silenced by RNAi in potato and tomato (only for DND1). DND1 well-silenced potato and tomato plants showed significantly reduced diameters of B. cinerea lesions as compared to control plants, at all-time points analysed. Reduced lesion diameter was also observed on leaves of DMR6 silenced potato plants but only at 3 days post inoculation (dpi). The DMR1 and PMR4 silenced potato transformants were as susceptible as the control cv Desiree. Microscopic analysis was performed to observe B. cinerea infection progress in DND1 well-silenced potato and tomato leaves. A significantly lower number of B. cinerea conidia remained attached to the leaf surface of DND1 well-silenced potato and tomato plants and the hyphal growth of germlings was hampered. This is the first report of a cytological investigation of Botrytis development on DND1-silenced crop plants. Silencing of DND1 led to reduced susceptibility to Botrytis, which was associated with impediment of conidial germination and attachment as well as hyphal growth. Our results provide new insights regarding the use of S genes in resistance breeding.

  3. Vertical diffuse attenuation coefficient (Kd) based optical ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    The optical classification of the different water types provides vital input for studies related to primary productivity, water clarity and determination of euphotic depth. Image data of the IRS-. P3 MOS-B, for Path 90 of 27th February, 1998 was used for deriving vertical diffuse attenuation coefficient (Kd) and an optical ...

  4. Coffee Consumption Attenuates Insulin Resistance and Glucose ...

    African Journals Online (AJOL)

    Coffee Consumption Attenuates Insulin Resistance and Glucose Intolerance in Rats fed on High-Sucrose Diet. ... Summary: Several epidemiological evidences indicate that consumption of coffee is associated with a lower risk of type 2 diabetes mellitus (T2DM) however; there is dearth of experimental data to support these ...

  5. Mycoplasma gallisepticum: Control by live attenuated vaccines

    Science.gov (United States)

    Commercially available attenuated strains of Mycoplasma gallisepticum (MG) are commonly used within the layer industry to control MG-induced mycoplasmosis. Among these are two live MG vaccines derived from the moderately pathogenic MG “chick F” strain. In the present study, the commercially availa...

  6. Mirtazapine attenuates cocaine seeking in rats.

    Science.gov (United States)

    Barbosa-Méndez, Susana; Leff, Phillipe; Arías-Caballero, Adriana; Hernández-Miramontes, Ricardo; Heinze, Gerardo; Salazar-Juárez, Alberto

    2017-09-01

    Relapse to cocaine use is a major problem in the clinical treatment of cocaine addiction. Antidepressants have been studied for their therapeutic potential to treat cocaine use disorder. Research has suggested that antidepressants attenuate both drug craving and the re-acquisition of drug-seeking and drug-taking behaviors. This study examined the efficacy of mirtazapine, an antidepressant/anxiolytic, in decreasing cocaine seeking in rats. We used the cocaine self-administration paradigm to assess the effects of mirtazapine on rats trained to self-administer cocaine or food under a fixed-ratio schedule. Mirtazapine (30 mg/kg, i.p.) was administered during extinction. Mirtazapine significantly attenuated non-reinforced lever-press responses during extinction. Moreover, the mirtazapine dosed for 30 days during extinction produced sustained attenuation of lever-press responses during re-acquisition of cocaine self-administration, without changing food-seeking behavior. Our results showed that mirtazapine attenuated the re-acquisition of cocaine-seeking responses. Our study pointed to the efficacy of mirtazapine in reducing the risk of drug relapse during abstinence, suggesting for its potential use as a novel pharmacological agent to treat drug abuse. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Touch Attenuates Infants' Physiological Reactivity to Stress

    Science.gov (United States)

    Feldman, Ruth; Singer, Magi; Zagoory, Orna

    2010-01-01

    Animal studies demonstrate that maternal touch and contact regulate infant stress, and handling during periods of maternal deprivation attenuates the stress response. To measure the effects of touch on infant stress reactivity during simulated maternal deprivation, 53 dyads were tested in two paradigms: still-face (SF) and still-face with maternal…

  8. Vertical diffuse attenuation coefficient (Kd) based optical ...

    Indian Academy of Sciences (India)

    The optical classification of the different water types provides vital input for studies related to primary productivity, water clarity and determination of euphotic depth. Image data of the IRS- P3 MOS-B, for Path 90 of 27th February, 1998 was used for deriving vertical diffuse attenuation Coeffcient () and an optical ...

  9. Infrared Attenuation Of Thallium Bromoiodide Fibers

    Science.gov (United States)

    Goebel, John; Magilavy, Beryl

    1988-01-01

    Report presents measurements of attenuation of infrared signals in unclad 381-micrometer-diameter optical fibers of thallium bromoiodide. Measurements of attentuation in TI(Br,I) fibers in wavelength ranges of 1.2 to 3.4 micrometer and 3 to 11 micrometer compare with those of two other groups of researchers.

  10. Attenuation correction for small animal PET tomographs

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Patrick L [David Geffen School of Medicine at UCLA, Crump Institute for Molecular Imaging, University of California, 700 Westwood Plaza, Los Angeles, CA 90095 (United States); Rannou, Fernando R [Departamento de Ingenieria Informatica, Universidad de Santiago de Chile (USACH), Av. Ecuador 3659, Santiago (Chile); Chatziioannou, Arion F [David Geffen School of Medicine at UCLA, Crump Institute for Molecular Imaging, University of California, 700 Westwood Plaza, Los Angeles, CA 90095 (United States)

    2005-04-21

    Attenuation correction is one of the important corrections required for quantitative positron emission tomography (PET). This work will compare the quantitative accuracy of attenuation correction using a simple global scale factor with traditional transmission-based methods acquired either with a small animal PET or a small animal x-ray computed tomography (CT) scanner. Two phantoms (one mouse-sized and one rat-sized) and two animal subjects (one mouse and one rat) were scanned in CTI Concorde Microsystem's microPET (registered) Focus{sup TM} for emission and transmission data and in ImTek's MicroCAT{sup TM} II for transmission data. PET emission image values were calibrated against a scintillation well counter. Results indicate that the scale factor method of attenuation correction places the average measured activity concentration about the expected value, without correcting for the cupping artefact from attenuation. Noise analysis in the phantom studies with the PET-based method shows that noise in the transmission data increases the noise in the corrected emission data. The CT-based method was accurate and delivered low-noise images suitable for both PET data correction and PET tracer localization.

  11. GPR measurements of attenuation in concrete

    Energy Technology Data Exchange (ETDEWEB)

    Eisenmann, David, E-mail: djeisen@cnde.iastate.edu; Margetan, Frank J., E-mail: djeisen@cnde.iastate.edu; Pavel, Brittney, E-mail: djeisen@cnde.iastate.edu [Center for Nondestructive Evaluation, Iowa State University, 1915 Scholl Road, Ames, IA 50011-3042 (United States)

    2015-03-31

    Ground-penetrating radar (GPR) signals from concrete structures are affected by several phenomenon, including: (1) transmission and reflection coefficients at interfaces; (2) the radiation patterns of the antenna(s) being used; and (3) the material properties of concrete and any embedded objects. In this paper we investigate different schemes for determining the electromagnetic (EM) attenuation of concrete from measured signals obtained using commercially-available GPR equipment. We adapt procedures commonly used in ultrasonic inspections where one compares the relative strengths of two or more signals having different travel paths through the material of interest. After correcting for beam spread (i.e., diffraction), interface phenomena, and equipment amplification settings, any remaining signal differences are assumed to be due to attenuation thus allowing the attenuation coefficient (say, in dB of loss per inch of travel) to be estimated. We begin with a brief overview of our approach, and then discuss how diffraction corrections were determined for our two 1.6 GHz GPR antennas. We then present results of attenuation measurements for two types of concrete using both pulse/echo and pitch/catch measurement setups.

  12. GPR measurements of attenuation in concrete

    International Nuclear Information System (INIS)

    Eisenmann, David; Margetan, Frank J.; Pavel, Brittney

    2015-01-01

    Ground-penetrating radar (GPR) signals from concrete structures are affected by several phenomenon, including: (1) transmission and reflection coefficients at interfaces; (2) the radiation patterns of the antenna(s) being used; and (3) the material properties of concrete and any embedded objects. In this paper we investigate different schemes for determining the electromagnetic (EM) attenuation of concrete from measured signals obtained using commercially-available GPR equipment. We adapt procedures commonly used in ultrasonic inspections where one compares the relative strengths of two or more signals having different travel paths through the material of interest. After correcting for beam spread (i.e., diffraction), interface phenomena, and equipment amplification settings, any remaining signal differences are assumed to be due to attenuation thus allowing the attenuation coefficient (say, in dB of loss per inch of travel) to be estimated. We begin with a brief overview of our approach, and then discuss how diffraction corrections were determined for our two 1.6 GHz GPR antennas. We then present results of attenuation measurements for two types of concrete using both pulse/echo and pitch/catch measurement setups

  13. Microwave attenuation with composite of copper microwires

    International Nuclear Information System (INIS)

    Gorriti, A.G.; Marin, P.; Cortina, D.; Hernando, A.

    2010-01-01

    It is shown that copper microwires composite media attenuates microwave reflection of metallic surfaces. We show how the distance to the metallic surface, as well as the length and volume fraction of microwires, determine the frequency of maximum absorption and the return loss level. Furthermore, we were able to fit the experimental results with a theoretical model based on Maxwell-Garnett mixing formula.

  14. Microwave attenuation with composite of copper microwires

    Energy Technology Data Exchange (ETDEWEB)

    Gorriti, A.G.; Marin, P. [Instituto de Magnetismo Aplicado, (UCM-ADIF-CSIC) and Departamento de Fisica de Materiales (UCM). P.O. Box 155, Las Rozas, Madrid 28230 (Spain); Cortina, D. [Micromag S.L., Las Rozas, Madrid 28230 (Spain); Hernando, A., E-mail: antonio.hernando@adif.e [Instituto de Magnetismo Aplicado, (UCM-ADIF-CSIC) and Departamento de Fisica de Materiales (UCM). P.O. Box 155, Las Rozas, Madrid 28230 (Spain); Micromag S.L., Las Rozas, Madrid 28230 (Spain)

    2010-05-15

    It is shown that copper microwires composite media attenuates microwave reflection of metallic surfaces. We show how the distance to the metallic surface, as well as the length and volume fraction of microwires, determine the frequency of maximum absorption and the return loss level. Furthermore, we were able to fit the experimental results with a theoretical model based on Maxwell-Garnett mixing formula.

  15. Coffee Consumption Attenuates Insulin Resistance and Glucose ...

    African Journals Online (AJOL)

    olayemitoyin

    J. Physiol. Sci. 28(December 2013) 179–185 www.njps.com.ng. Coffee Consumption Attenuates Insulin Resistance and Glucose. Intolerance in Rats fed on High-Sucrose Diet. Morakinyo AO*, Adekunbi DA, Dada KA and Adegoke OA. Department of Physiology, College of Medicine of the University of Lagos, Lagos. Nigeria.

  16. Anethum Graveolens Linn (Umbelliferae) Extract Attenuates Stress ...

    African Journals Online (AJOL)

    Anethum Graveolens Linn (Umbelliferae) Extract Attenuates Stress-induced Urinary Biochemical Changes and Improves Cognition in Scopolamineinduced Amnesic Rats. ... Conclusion: The aqueous extract of A. graveolens exhibited significant anti-stress, antioxidant and memory enhancing activities. The study provides a ...

  17. Virus-Induced Gene Silencing-Based Functional Analyses Revealed the Involvement of Several Putative Trehalose-6-Phosphate Synthase/Phosphatase Genes in Disease Resistance against Botrytis cinerea and Pseudomonas syringae pv. tomato DC3000 in Tomato.

    Science.gov (United States)

    Zhang, Huijuan; Hong, Yongbo; Huang, Lei; Liu, Shixia; Tian, Limei; Dai, Yi; Cao, Zhongye; Huang, Lihong; Li, Dayong; Song, Fengming

    2016-01-01

    Trehalose and its metabolism have been demonstrated to play important roles in control of plant growth, development, and stress responses. However, direct genetic evidence supporting the functions of trehalose and its metabolism in defense response against pathogens is lacking. In the present study, genome-wide characterization of putative trehalose-related genes identified 11 SlTPSs for trehalose-6-phosphate synthase, 8 SlTPPs for trehalose-6-phosphate phosphatase and one SlTRE1 for trehalase in tomato genome. Nine SlTPSs, 4 SlTPPs, and SlTRE1 were selected for functional analyses to explore their involvement in tomato disease resistance. Some selected SlTPSs, SlTPPs, and SlTRE1 responded with distinct expression induction patterns to Botrytis cinerea and Pseudomonas syringae pv. tomato (Pst) DC3000 as well as to defense signaling hormones (e.g., salicylic acid, jasmonic acid, and a precursor of ethylene). Virus-induced gene silencing-mediated silencing of SlTPS3, SlTPS4, or SlTPS7 led to deregulation of ROS accumulation and attenuated the expression of defense-related genes upon pathogen infection and thus deteriorated the resistance against B. cinerea or Pst DC3000. By contrast, silencing of SlTPS5 or SlTPP2 led to an increased expression of the defense-related genes upon pathogen infection and conferred an increased resistance against Pst DC3000. Silencing of SlTPS3, SlTPS4, SlTPS5, SlTPS7, or SlTPP2 affected trehalose level in tomato plants with or without infection of B. cinerea or Pst DC3000. These results demonstrate that SlTPS3, SlTPS4, SlTPS5, SlTPS7, and SlTPP2 play roles in resistance against B. cinerea and Pst DC3000, implying the importance of trehalose and tis metabolism in regulation of defense response against pathogens in tomato.

  18. Virus-induced Gene Silencing-based Functional Analyses Revealed the Involvement of Several Putative Trehalose-6-Phosphate Synthase/Phosphatase Genes in Disease Resistance against Botrytis cinerea and Pseudomonas syringae pv. tomato DC3000 in Tomato

    Directory of Open Access Journals (Sweden)

    Huijuan Zhang

    2016-08-01

    Full Text Available Trehalose and its metabolism have been demonstrated to play important roles in control of plant growth, development and stress responses. However, direct genetic evidence supporting the functions of trehalose and its metabolism in defense response against pathogens is lacking. In the present study, genome-wide characterization of putative trehalose-related genes identified 11 SlTPSs for trehalose-6-phosphate synthase, 8 SlTPPs for trehalose-6-phosphate phosphatase and one SlTRE1 for trehalase in tomato genome. Nine SlTPSs, 4 SlTPPs and SlTRE1 were selected for functional analyses to explore their involvement in tomato disease resistance. Some selected SlTPSs, SlTPPs and SlTRE1 responded with distinct expression induction patterns to Botrytis cinerea and Pseudomonas syringae pv. tomato (Pst DC3000 as well as to defense signaling hormones (e.g. salicylic acid, jasmonic acid and a precursor of ethylene. Virus-induced gene silencing-mediated silencing of SlTPS3, SlTPS4 or SlTPS7 led to deregulation of ROS accumulation and attenuated the expression of defense-related genes upon pathogen infection and thus deteriorated the resistance against B. cinerea or Pst DC3000. By contrast, silencing of SlTPS5 or SlTPP2 led to an increased expression of the defense-related genes upon pathogen infection and conferred an increased resistance against Pst DC3000. Silencing of SlTPS3, SlTPS4, SlTPS5, SlTPS7 or SlTPP2 affected trehalose level in tomato plants with or without infection of B. cinerea or Pst DC3000. These results demonstrate that SlTPS3, SlTPS4, SlTPS5, SlTPS7 and SlTPP2 play roles in resistance against B. cinerea and Pst DC3000, implying the importance of trehalose and tis metabolism in regulation of defense response against pathogens in tomato.

  19. Pnc1p-mediated nicotinamide clearance modifies the epigenetic properties of rDNA silencing in Saccharomyces cerevisiae.

    Science.gov (United States)

    McClure, Julie M; Gallo, Christopher M; Smith, Daniel L; Matecic, Mirela; Hontz, Robert D; Buck, Stephen W; Racette, Frances G; Smith, Jeffrey S

    2008-10-01

    The histone deacetylase activity of Sir2p is dependent on NAD(+) and inhibited by nicotinamide (NAM). As a result, Sir2p-regulated processes in Saccharomyces cerevisiae such as silencing and replicative aging are susceptible to alterations in cellular NAD(+) and NAM levels. We have determined that high concentrations of NAM in the growth medium elevate the intracellular NAD(+) concentration through a mechanism that is partially dependent on NPT1, an important gene in the Preiss-Handler NAD(+) salvage pathway. Overexpression of the nicotinamidase, Pnc1p, prevents inhibition of Sir2p by the excess NAM while maintaining the elevated NAD(+) concentration. This growth condition alters the epigenetics of rDNA silencing, such that repression of a URA3 reporter gene located at the rDNA induces growth on media that either lacks uracil or contains 5-fluoroorotic acid (5-FOA), an unusual dual phenotype that is reminiscent of telomeric silencing (TPE) of URA3. Despite the similarities to TPE, the modified rDNA silencing phenotype does not require the SIR complex. Instead, it retains key characteristics of typical rDNA silencing, including RENT and Pol I dependence, as well as a requirement for the Preiss-Handler NAD(+) salvage pathway. Exogenous nicotinamide can therefore have negative or positive impacts on rDNA silencing, depending on the PNC1 expression level.

  20. Silencing of E2F3 suppresses tumor growth of Her2+ breast cancer cells by restricting mitosis.

    Science.gov (United States)

    Lee, Miyoung; Oprea-Ilies, Gabriela; Saavedra, Harold I

    2015-11-10

    The E2F transcriptional activators E2F1, E2F2 and E2F3a regulate many important cellular processes, including DNA replication, apoptosis and centrosome duplication. Previously, we demonstrated that silencing E2F1 or E2F3 suppresses centrosome amplification (CA) and chromosome instability (CIN) in Her2+ breast cancer cells without markedly altering proliferation. However, it is unknown whether and how silencing a single E2F activator, E2F3, affects malignancy of human breast cancer cells. Thus, we injected HCC1954 Her2+ breast cancer cells silenced for E2F3 into mammary fat pads of immunodeficient mice and demonstrated that loss of E2F3 retards tumor growth. Surprisingly, silencing of E2F3 led to significant reductions in mitotic indices relative to vector controls, while the percentage of cells undergoing S phase were not affected. Nek2 is a mitotic kinase commonly upregulated in breast cancers and a critical regulator of Cdk4- or E2F-mediated CA. In this report, we found that Nek2 overexpression rescued back the CA caused by silencing of shE2F3. However, the effects of Nek2 overexpression in affecting tumor growth rates of shE2F3 and shE2F3; GFP cells were inconclusive. Taken together, our results indicate that E2F3 silencing decreases mammary tumor growth by reducing percentage of cells undergoing mitosis.