Página 1 dos resultados de 3338 itens digitais encontrados em 0.065 segundos

Effect of contact and systemic insecticides on the sharpshooter Bucephalogonia xanthophis (Hemiptera: cicadellidae), a vector of Xylella fastidiosa in citrus

Bezerra-Silva, Gerane Celly Dias; Silva, Márcio Alves; Miranda, Marcelo Pedreira de; Lopes, Joao Roberto Spotti
Fonte: FLORIDA ENTOMOLOGICAL SOC; LUTZ Publicador: FLORIDA ENTOMOLOGICAL SOC; LUTZ
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
56.1%
The knockdown and toxic effects of insecticides of different chemical groups and modes of action registered for citrus in Brazil were investigated for effective control of Bucephalogonia xanthophis, a sharpshooter vector of Xylella fastidiosa in citrus. The active ingredients dimethoate (1.2 mL/1.2L), imidacloprid (0.24 mL/1.2L) and lambda-cyhalothrin (0.24 mL/1.2L), as well as a control (water), were sprayed onto branches of potted-citrus nursery trees to evaluate the effect of residual contact. The insects were confined on sprayed branches by using sleeve cages, in groups of 10 per branch (5 branches/treatment). Lambdacyhalothrin showed a knockdown effect on B. xanthophis (>70% mortality within 2 h of exposure), and the residues were effective for approximately one wk. Imidacloprid, lambdacyhalothrin and dimethoate suppressed the vector populations for up to 3 wk after application, when the insects were exposed to sprayed plants for at least 24 h. In another experiment, 2 neonicotinoid insecticides (thiamethoxam and imidacloprid) were applied by soil drench to potted nursery trees, in order to study their systemic effect, i.e., mortality by ingestion on sharpshooter adults. Thiamethoxam and imidacloprid effectively controlled the vectors at all concentrations tested...

O gene KIAA0090 é ativado em lesão pré-neoplásica e seu silenciamento por siRNA causa morte celular em linhagem de melanoma; KIAA0090 gene is activated in pre-neoplasic lesions and its knockdown causes cell death in melanoma strain

Silva, Rodrigo Ribeiro da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 11/06/2010 Português
Relevância na Pesquisa
36.02%
O gene KIAA0090, encontrado em todos os genomas eucariotos, está localizado em uma região cromossômica (1p36.13) com alta freqüência de aberrações em tumores humanos. Além disso, os perfis de expressão disponíveis em bancos de dados públicos sugerem expressão alterada deste gene em muitos tumores e em resposta a diferentes tratamentos. Os objetivos deste trabalho foram investigar a possível ocorrência de múltiplos transcritos do gene KIAA0090 em linhagens celulares de melanoma humano; avaliar o padrão de expressão do gene em diferentes linhagens celulares e amostras de tumores, por RT-PCR tempo-real; e analisar o efeito do knockdown deste gene sobre a viabilidade de células de melanoma. O transcrito que observamos estar expresso em linhagem de células de melanoma parece corresponder à RefSeq completa. Observamos aumento da expressão do gene KIAA0090 em todas as linhagens celulares de melanoma humano em comparação com melanócitos. Curiosamente, entretanto, observou-se expressão significativamente maior em amostras de nevos (média = 11,02) em relação a melanoma primário (média = 2,87) ou metastático (média = 2,72) (p <0,01). Não houve diferença significativa entre melanoma primário e metastático. O tratamento de células de melanoma...

A “knockdown” mutation created by cis-element gene targeting reveals the dependence of erythroid cell maturation on the level of transcription factor GATA-1

McDevitt, Michael A.; Shivdasani, Ramesh A.; Fujiwara, Yuko; Yang, Haidi; Orkin, Stuart H.
Fonte: The National Academy of Sciences of the USA Publicador: The National Academy of Sciences of the USA
Tipo: Artigo de Revista Científica
Publicado em 24/06/1997 Português
Relevância na Pesquisa
35.88%
The hematopoietic-restricted transcription factor GATA-1 is required for both mammalian erythroid cell and megakaryocyte differentiation. To define the mechanisms governing its transcriptional regulation, we replaced upstream sequences including a DNase I hypersensitive (HS) region with a neomycin-resistance cassette by homologous recombination in mouse embryonic stem cells and generated mice either harboring this mutation (neoΔHS) or lacking the selection cassette (ΔneoΔHS). Studies of the consequences of these targeted mutations provide novel insights into GATA-1 function in erythroid cells. First, the neoΔHS mutation leads to a marked impairment in the rate or efficiency of erythroid cell maturation due to a modest (4- to 5-fold) decrease in GATA-1 expression. Hence, erythroid differentiation is dose-dependent with respect to GATA-1. Second, since expression of GATA-1 from the ΔneoΔHS allele in erythroid cells is largely restored, transcription interference imposed by the introduced cassette must account for the “knockdown” effect of the mutation. Finally, despite the potency of the upstream sequences in conferring high-level, developmentally appropriate expression of transgenes in mice, other cis-regulatory elements within the GATA-1 compensate for its absence in erythroid cells. Our work illustrates the usefulness of targeted mutations to create knockdown mutations that may uncover important quantitative contributions of gene function not revealed by conventional knockouts.

Effect of Hepatitis C Virus (HCV) NS5B-Nucleolin Interaction on HCV Replication with HCV Subgenomic Replicon

Shimakami, Tetsuro; Honda, Masao; Kusakawa, Takashi; Murata, Takayuki; Shimotohno, Kunitada; Kaneko, Shuichi; Murakami, Seishi
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /04/2006 Português
Relevância na Pesquisa
35.71%
We previously reported that nucleolin, a representative nucleolar marker, interacts with nonstructural protein 5B (NS5B) of hepatitis C virus (HCV) through two independent regions of NS5B, amino acids 208 to 214 and 500 to 506. We also showed that truncated nucleolin that harbors the NS5B-binding region inhibited the RNA-dependent RNA polymerase activity of NS5B in vitro, suggesting that nucleolin may be involved in HCV replication. To address this question, we focused on NS5B amino acids 208 to 214. We constructed one alanine-substituted clustered mutant (CM) replicon, in which all the amino acids in this region were changed to alanine, as well as seven different point mutant (PM) replicons, each of which harbored an alanine substitution at one of the amino acids in the region. After transfection into Huh7 cells, the CM replicon and the PM replicon containing NS5B W208A could not replicate, whereas the remaining PM replicons were able to replicate. In vivo immunoprecipitation also showed that the W208 residue of NS5B was essential for its interaction with nucleolin, strongly suggesting that this interaction is essential for HCV replication. To gain further insight into the role of nucleolin in HCV replication, we utilized the small interfering RNA (siRNA) technique to investigate the knockdown effect of nucleolin on HCV replication. Cotransfection of replicon RNA and nucleolin siRNA into Huh7 cells moderately inhibited HCV replication...

p53 Activation by Knockdown Technologies

Robu, Mara E; Larson, Jon D; Nasevicius, Aidas; Beiraghi, Soraya; Brenner, Charles; Farber, Steven A; Ekker, Stephen C
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.07%
Morpholino phosphorodiamidate antisense oligonucleotides (MOs) and short interfering RNAs (siRNAs) are commonly used platforms to study gene function by sequence-specific knockdown. Both technologies, however, can elicit undesirable off-target effects. We have used several model genes to study these effects in detail in the zebrafish, Danio rerio. Using the zebrafish embryo as a template, correct and mistargeting effects are readily discernible through direct comparison of MO-injected animals with well-studied mutants. We show here indistinguishable off-targeting effects for both maternal and zygotic mRNAs and for both translational and splice-site targeting MOs. The major off-targeting effect is mediated through p53 activation, as detected through the transferase-mediated dUTP nick end labeling assay, acridine orange, and p21 transcriptional activation assays. Concurrent knockdown of p53 specifically ameliorates the cell death induced by MO off-targeting. Importantly, reversal of p53-dependent cell death by p53 knockdown does not affect specific loss of gene function, such as the cell death caused by loss of function of chordin. Interestingly, quantitative reverse-transcriptase PCR, microarrays and whole-mount in situ hybridization assays show that MO off-targeting effects are accompanied by diagnostic transcription of an N-terminal truncated p53 isoform that uses a recently recognized internal p53 promoter. We show here that MO off-targeting results in induction of a p53-dependent cell death pathway. p53 activation has also recently been shown to be an unspecified off-target effect of siRNAs. Both commonly used knockdown technologies can thus induce secondary but sequence-specific p53 activation. p53 inhibition could potentially be applicable to other systems to suppress off-target effects caused by other knockdown technologies.

The effect of mutant SOD1 dismutase activity on non-cell autonomous degeneration in familial amyotrophic lateral sclerosis

Wang, Lijun; Sharma, Kamal; Grisotti, Gabriella; Roos, Raymond P.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.05%
Mutant superoxide dismutase type 1 (MTSOD1), the most common known cause of familial amyotrophic lateral sclerosis (FALS), is believed to cause FALS as a result of a toxicity of the protein. MTSOD1s with full dismutase enzymatic activity (e.g., G37R) and without any enzymatic activity (e.g., G85R) cause FALS, demonstrating that the ability of MTSOD1 to cause FALS is not dependent on the dismutase activity; however, it remains unclear whether MTSOD1 dismutase activity can influence disease phenotype. In the present study, we selectively knocked down G85R expression in particular cell types of G85R mice. Results following knockdown of G85R in motor neurons (MNs)/interneurons of G85R mice were similar to results from a published study involving knockdown of G37R in G37R mice; however, G85R knockdown in microglia/macrophages induced a prolonged early and late disease phase while G37R knockdown in the same cells only affected late phase. These results show that: (i) MN as well as non-MN expression of G85R, like G37R, has a significant effect on disease in transgenic mice – indicating the role of non-cell autonomous degeneration in both dismutase active and inactive MTSOD1. (ii) The effect of MTSOD1 expression in microglia/macrophages varies with different mutants...

Mutant SOD1 knockdown in all cell types ameliorates disease in G85R SOD1 mice with a limited additional effect over knockdown restricted to motor neurons

Wang, Lijun; Grisotti, Gabriella; Roos, Raymond P.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.13%
Approximately10% of patients with amyotrophic lateral sclerosis (ALS) have familial ALS (FALS), and 20% of FALS is caused by mutant Cu/Zn superoxide dismutase type 1 (MTSOD1). Previous studies have convincingly demonstrated that MTSOD1 expression in other cell types besides motor neurons (MNs) contributes to disease in MTSOD1 FALS transgenic mice. Using Cre/LoxP methods, we knocked down G85R SOD1 mRNA by 66% in all cell types in 3-month-old FALS transgenic mice, delaying disease onset and lengthening disease duration. Surprisingly, the effect on onset and early disease duration was similar to that seen with ~25% knockdown prenatally in G85R SOD1 mRNA restricted to MNs and some interneurons in FALS transgenic mice. These results demonstrate no clear cumulative effect on disease onset or early disease duration from knocking down G85R SOD1 in other cell types in addition to MNs/interneurons; the findings bring up the possibility that MTSOD1 has a pathogenic effect early in life that our later knockdown did not affect. Despite the more limited amelioration of disease than expected, the effect of the knockdown on disease supports the value of this approach in FALS patients and asymptomatic individuals with SOD1 mutations.

Effect of retinoic acid and delta-like 1 homologue (DLK1) on differentiation in neuroblastoma

Kim, Yuri
Fonte: The Korean Nutrition Society and the Korean Society of Community Nutrition Publicador: The Korean Nutrition Society and the Korean Society of Community Nutrition
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.14%
The principal objective of this study was to evaluate the chemopreventive and therapeutic effects of a combination of all-trans-retinoic acid (RA) and knockdown of delta-like 1 homologue (Drosophila) (DLK1) on neuroblastoma, the most common malignant disease in children. As unfavorable neuroblastoma is poorly differentiated, neuroblastoma cell was induced differentiation by RA or DLK1 knockdown. Neuroblastoma cells showed elongated neurite growth, a hallmark of neuronal differentiation at various doses of RA, as well as by DLK1 knockdown. In order to determine whether or not a combination of RA and DLK1 knockdown exerts a greater chemotherapeutic effect on neuroblastoma, cells were incubated at 10 nM RA after being transfected with SiRNA-DLK1. Neuronal differentiation was increased more by a combination of RA and DLK1 knockdown than by single treatment. Additionally, in order to assess the signal pathway of neuroblastoma differentiation induced by RA and DLK1 knockdown, treatment with the specific MEK/ERK inhibitors, U0126 and PD 98059, was applied to differentiated neuroblastoma cells. Differentiation induced by RA and DLK1 knockdown increased ERK phosphorylation. The MEK/ERK inhibitor U0126 completely inhibited neuronal differentiation induced by both RA and DLK1 knockdown...

In vivo knockdown of GAD67 in the amygdala disrupts fear extinction and the anxiolytic-like effect of diazepam in mice

Heldt, S A; Mou, L; Ressler, K J
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.05%
In mammals, γ-aminobutyric acid (GABA) transmission in the amygdala is particularly important for controlling levels of fear and anxiety. Most GABA synthesis in the brain is catalyzed in inhibitory neurons from ℒ-glutamic acid by the enzyme glutamic acid decarboxylase 67 (GAD67). In the current study, we sought to examine the acquisition and extinction of conditioned fear in mice with knocked down expression of the GABA synthesizing enzyme GAD67 in the amygdala using a lentiviral-based (LV) RNA interference strategy to locally induce loss-of-function. In vitro experiments revealed that our LV-siRNA-GAD67 construct diminished the expression of GAD67 as determined with western blot and fluorescent immunocytochemical analyses. In vivo experiments, in which male C57BL/6J mice received bilateral amygdala microinjections, revealed that LV-siRNA-GAD67 injections produce significant inhibition of endogenous GAD67 when compared with control injections. In contrast, no significant changes in GAD65 expression were detected in the amygdala, validating the specificity of LV knockdown. Behavioral experiments showed that LV knockdown of GAD67 results in a deficit in the extinction, but not the acquisition or retention, of fear as measured by conditioned freezing. GAD67 knockdown did not affect baseline locomotion or basal measures of anxiety as measured in open field apparatus. However...

The Effect of Msh2 Knockdown on Toxicity Induced by tert-Butyl-hydroperoxide, Potassium Bromate, and Hydrogen Peroxide in Base Excision Repair Proficient and Deficient Cells

Cooley, N.; Elder, R. H.; Povey, A. C.
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.11%
The DNA mismatch repair (MMR) and base excision repair (BER) systems are important determinants of cellular toxicity following exposure to agents that cause oxidative DNA damage. To examine the interactions between these different repair systems, we examined whether toxicity, induced by t-BOOH and KBrO3, differs in BER proficient (Mpg+/+, Nth1+/+) and deficient (Mpg−/−, Nth1−/−) mouse embryonic fibroblasts (MEFs) following Msh2 knockdown of between 79 and 88% using an shRNA expression vector. Msh2 knockdown in Nth1+/+ cells had no effect on t-BOOH and KBrO3 induced toxicity as assessed by an MTT assay; knockdown in Nth1−/− cells resulted in increased resistance to t-BOOH and KBrO3, a result consistent with Nth1 removing oxidised pyrimidines. Msh2 knockdown in Mpg+/+ cells had no effect on t-BOOH toxicity but increased resistance to KBrO3; in Mpg−/− cells, Msh2 knockdown increased cellular sensitivity to KBrO3 but increased resistance to t-BOOH, suggesting a role for Mpg in removing DNA damage induced by these agents. MSH2 dependent and independent pathways then determine cellular toxicity induced by oxidising agents. A complex interaction between MMR and BER repair systems, that is, exposure dependent, also exists to determine cellular toxicity.

KNDC1 knockdown protects human umbilical vein endothelial cells from senescence

ZHANG, CHUNYAN; ZHEN, YONG-ZHAN; LIN, YA-JUN; LIU, JIANG; WEI, JIE; XU, RONG; HU, GANG
Fonte: D.A. Spandidos Publicador: D.A. Spandidos
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
26.09%
KNDC1 (kinase noncatalytic C-lobe domain containing 1), a brain-specific Ras guanine nucleotide exchange factor, controls the negative regulation of neuronal dendrite growth. However, the effect of KNDC1 on cellular senescence remains to be elucidated. The present study investigated the impact of KNDC1 knockdown on human endothelial cell senescence and the mechanisms underlying this effect. Human umbilical vein endothelial cells (HUVECs) cultured in vitro were used as a model of biological aging. Senescence-associated β-galactosidase staining was used to detect cellular senescence and flow cytometry was employed to determine cell cycle progression. Quantitative polymerase chain reaction (qPCR) and western blot analysis were utilized to investigate mRNA transcription and protein expression. In the HUVECs, a senescence-like phenotypes developed with increasing passage number in vitro, which were associated with a progressive increase in the transcription and expression of KNDC1. KNDC1 knockdown promoted cell proliferation and partially reversed cellular senescence and cell cycle arrest in the G0/G1 phase in aging HUVECs. Investigations into the mechanism underlying this effect demonstrated that KNDC1 knockdown promoted HUVEC proliferation via the extracellular signal-regulated kinase signaling pathway and delayed HUVEC senescence by inhibiting the p53-p21-p16 transduction cascade. In addition...

Knockdown of EpCAM Enhances the Chemosensitivity of Breast Cancer Cells to 5-fluorouracil by Downregulating the Antiapoptotic Factor Bcl-2

Gao, Jiujiao; Yan, Qiu; Liu, Shuai; Yang, Xuesong
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 14/07/2014 Português
Relevância na Pesquisa
26.09%
Resistance to fluoropyrimidine-based chemotherapy is the main reason for the failure of cancer treatment, and drug resistance is associated with an inability of tumor cells to undergo apoptosis in response to treatment. Alterations in the expression of epithelial cell adhesion molecule (EpCAM) affect the sensitivity or resistance of tumor cells to anticancer treatment and the activity of intracellular signaling pathways. However, the role of EpCAM in the induction of apoptosis in breast cancer cells remains unclear. Here, we investigated the effect of EpCAM gene knockdown on chemosensitivity to 5-fluorouracil (5-FU) in MCF-7 cells and explored the underlying mechanisms. Our results showed that knockdown of EpCAM promoted apoptosis, inhibited cell proliferation and caused cell-cycle arrest. EpCAM knockdown enhanced the cytotoxic effect of 5-FU, promoting apoptosis by downregulating the expression of the anti-apoptotic protein Bcl-2 and upregulating the expression of the pro-apoptotic proteins Bax, and caspase3 via the ERK1/2 and JNK MAPK signaling pathways in MCF-7 cells. These results indicate that knockdown of EpCAM may have a tumor suppressor effect and suggest EpCAM as a potential target for the treatment of breast cancer.

CRISPR/Cas9-based generation of knockdown mice by intronic insertion of artificial microRNA using longer single-stranded DNA

Miura, Hiromi; Gurumurthy, Channabasavaiah B; Sato, Takehito; Sato, Masahiro; Ohtsuka, Masato
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 05/08/2015 Português
Relevância na Pesquisa
36.02%
Knockdown mouse models, where gene dosages can be modulated, provide valuable insights into gene function. Typically, such models are generated by embryonic stem (ES) cell-based targeted insertion, or pronuclear injection, of the knockdown expression cassette. However, these methods are associated with laborious and time-consuming steps, such as the generation of large constructs with elements needed for expression of a functional RNAi-cassette, ES-cell handling, or screening for mice with the desired knockdown effect. Here, we demonstrate that reliable knockdown models can be generated by targeted insertion of artificial microRNA (amiRNA) sequences into a specific locus in the genome [such as intronic regions of endogenous eukaryotic translation elongation factor 2 (eEF-2) gene] using the Clustered Regularly Interspaced Short Palindromic Repeats/Crispr associated 9 (CRISPR/Cas9) system. We used in vitro synthesized single-stranded DNAs (about 0.5-kb long) that code for amiRNA sequences as repair templates in CRISPR/Cas9 mutagenesis. Using this approach we demonstrate that amiRNA cassettes against exogenous (eGFP) or endogenous [orthodenticle homeobox 2 (Otx2)] genes can be efficiently targeted to a predetermined locus in the genome and result in knockdown of gene expression. We also provide a strategy to establish conditional knockdown models with this method.

Assessment of Artificial MiRNA Architectures for Higher Knockdown Efficiencies without the Undesired Effects in Mice

Miura, Hiromi; Inoko, Hidetoshi; Tanaka, Masafumi; Nakaoka, Hirofumi; Kimura, Minoru; Gurumurthy, Channabasavaiah B.; Sato, Masahiro; Ohtsuka, Masato
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 18/08/2015 Português
Relevância na Pesquisa
35.97%
RNAi-based strategies have been used for hypomorphic analyses. However, there are technical challenges to achieve robust, reproducible knockdown effect. Here we examined the artificial microRNA (amiRNA) architectures that could provide higher knockdown efficiencies. Using transient and stable transfection assays in cells, we found that simple amiRNA-expression cassettes, that did not contain a marker gene (−MG), displayed higher amiRNA expression and more efficient knockdown than those that contained a marker gene (+MG). Further, we tested this phenomenon in vivo, by analyzing amiRNA-expressing mice that were produced by the pronuclear injection-based targeted transgenesis (PITT) method. While we observed significant silencing of the target gene (eGFP) in +MG hemizygous mice, obtaining −MG amiRNA expression mice, even hemizygotes, was difficult and the animals died perinatally. We obtained only mosaic mice having both “−MG amiRNA” cells and “amiRNA low-expression” cells but they exhibited growth retardation and cataracts, and they could not transmit the –MG amiRNA allele to the next generation. Furthermore, +MG amiRNA homozygotes could not be obtained. These results suggested that excessive amiRNAs transcribed by −MG expression cassettes cause deleterious effects in mice...

The Effect of NRAGE on cell cycle and apoptosis of human dental pulp cells and MDPC-23

Wu, Qi; Qi, Shengcai; Ma, Ji; Chen, Fubo; Chen, Jing; Li, Jing; Zhang, Xu; Xu, Yuanzhi; Pan, Qiuhui; Wang, Raorao
Fonte: e-Century Publishing Corporation Publicador: e-Century Publishing Corporation
Tipo: Artigo de Revista Científica
Publicado em 15/07/2015 Português
Relevância na Pesquisa
26.07%
Objectives: Neurotrophin receptor-mediated melanoma antigen-encoding gene homology (NRAGE) is an important regulator of proliferation, cell cycle arrest and apoptosis. Our previous study showed that NRAGE is an important regulator of proliferation and odontogenic differentiation of mouse dental pulp cells. This study aimed to investigate the effects of NRAGE on the cell cycle and apoptosis on human dental pulp cells (hDPCs) and MDPC-23. Materials and methods: Cells were infected by recombinant lentivirus to stably knockdown the expression of NRAGE, then the biological effects of NRAGE on the MDPC-23 was detected. The cell cycle distributions and apoptosis of hDPCs and MCPC-23 were performed by flow cytometric analysis. Simultaneously, the cell cycle and apoptosis were also detected after cells treated with IKK inhibitor. Results: The mRNA and protein levels of NRAGE decreased significantly after infected by recombinant lentivirus. Knockdown of NRAGE inhibited the apoptosis in hDPCs and MCPC-23. Knockdown of NRAGE show significantly G0G1 arrest in hDPCs, while no significantly difference in MDPC-23. Meanwhile, Knockdown of NRAGE activated the NF-κB signaling pathway. After treated with IKK inhibitor, the effect of NRAGE knockdown on apoptosis was reversed in both hDPCs and MDPC-23. Conclusion: NRAGE is a potent regulator for cell cycle and apoptosis of hDPCs. Knockdown of NRAGE inhibited apoptosis of hDPCs and MDPC-23 through the NF-κB signaling pathway.

Effect of Pyrethroids on Knockdown and Lack of Coordination Responses of Susceptible and Resistant Diamondback Moth (Lepidoptera: Plutellidae)

Chen, J. S.; Lee, C. J.; Yao, M. G.; Sun, C. N.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
Português
Relevância na Pesquisa
36.13%
Among DDT and the 10 pyrethroids tested, permethrin, cypermethrin, deltamethrin, and fenvalerate were most toxic against a field strain of Plutella xylostella (L.) that had high levels of resistance to all insecticides tested. Knockdown effect of these compounds against larvae and adults of susceptible and resistant strains was evaluated by a residual-film method. Symptoms of poisoning are described. When larvae or adults could no longer stand and had to lie on their sides, they were considered knocked down. Pyrethroids with primary alcohol esters produced more acute symptoms than those with secondary alcohol esters. Responses of resistant larvae and adults were less pronounced than those of susceptible ones. In the resistant strain, addition of synergist piperonyl butoxide (PB) to the pyrethroids produced symptoms displayed by the susceptible strain. Tetramethrin, which was not highly toxic, was the most potent knockdown agent against susceptible larvae. Knockdown action of all pyrethroids appeared much more slowly in resistant larvae; fluvalin ate and flucythrinate were least effective as knockdown as well as killing agents. Addition of synergists PB, S,S,S-tributyl phosphorotrithioate, and chlordimeform generally enhanced knockdown action of most pyrethroids in resistant larvae...

Knockdown Mortality, Repellency, and Residual Effects of Insecticides for Control of Adult Bactericera cockerelli (Hemiptera: Psyllidae)

Gharalari, A. H.; Nansen, C.; Lawson, D. S.; Gilley, J.; Munyaneza, J. E.; Vaughn, K.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
Português
Relevância na Pesquisa
36%
The psyllid Bactericera cockerelli (Sulc) (Hemiptera: Psyllidae) is the vector of a bacterial pathogen causing zebra chip (ZC) disease in potato, Solanum tuberosum L. (Solanaceae). Recently, ZC has become important to potato growers and the potato chipping industry in the southwestern United States, Mexico, Central America, and New Zealand. In the current study, we evaluated the knockdown effect of 12 insecticides against adult B. cockerelli, and we examined the effects of treating potato leaves: top side only, bottom side only, or both sides. Within 48 h of exposure, abamectin showed the highest and most consistent rate of adult B. cockerelli mortality and a dosage response to three dosages within labeled field rates. Choice tests conducted in petri dishes, involving untreated potato leaves and leaves treated with abamectin, revealed that abamectin did not affect host preference of adult B. cockerelli. A residual test under field conditions revealed that, although highly effective immediately after application, abamectin-effect was nonsignificantly different from control treatments 24 and 48 h after field application. Higher adult B. cockerelli mortality was recorded from potato plants treated with ground application compared with aerial 48 h after application. Our results indicated that abamectin has a high knockdown effect on adult B. cockerelli and that it can be used effectively in insecticide rotation programs against adult B. cockerelli and ZC control in potatoes.

Knockdown Factors for Buckling of Cylindrical and Spherical Shells Subject to Reduced Biaxial Membrane Stress

Hutchinson, John W.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
35.97%
Cylindrical shells under uniaxial compression and spherical shells under equi-biaxial compression display the most extreme buckling sensitivity to imperfections. In engineering practice, the reduction of load carrying capacity due to imperfections is usually addressed by use of a knockdown factor to lower the critical buckling stress estimated or computed without accounting for imperfections. For thin elastic cylindrical shells under uniaxial compression and spherical shells under equi-biaxial compression, the knockdown factor is typically as small as 0.2. This paper explores the alleviation of imperfection-sensitivity for loadings with a reduced circumferential (transverse) membrane stress component. The analysis of Koiter (1963) on the effect of an axisymmetric imperfection on the elastic buckling of a cylindrical shell under uniaxial compression is extended to both cylinders and spheres for loadings that produce general combinations of biaxial membrane stresses. Increases in the knockdown factor due to a reduction of the transverse membrane component are remarkably similar for cylindrical and spherical shells.; Engineering and Applied Sciences

RNA-interference methods for gene-knockdown in the sea louse, Lepeophtheirus salmonis: studies on a putative prostaglandin E synthase

Campbell, E.; Pert, C.; Bowman, A.
Fonte: Cambridge Univ Press Publicador: Cambridge Univ Press
Tipo: Artigo de Revista Científica
Publicado em //2009 Português
Relevância na Pesquisa
36.09%
Harnessing the full utility of extensive gene sequences recently available for the economically important sea louse, Lepeophtheirus salmonis, requires the adaptation of modern molecular biology approaches to this non-model organism. Using a putative microsomal prostaglandin E synthase type-2 (PGES2) as a candidate gene, we investigated gene-knockdown by double-stranded RNA interference (dsRNAi) in the small free-living and the larger parasitic stages of L. salmonis. dsRNA was administered to nauplius and copepodid stages by immersion for 7 h. Pre-adult and adults received dsRNA by intra-haemocoelic injection. The extent, speed and persistence of the knockdown effects were determined by RT-PCR. LsPGES2 was abundantly expressed in all life stages, including the non-parasitic stages. Administration of dsRNA to nauplius and copepodids by immersion had no effect on mortality rates and moulting through to copepodids was observed. Dramatic knockdown of LsPGES2 was observed within 7 h and persisted for at least 48 h. Injection of dsRNA had no effect on mortality in pre-adults and adults, but knockdown of LsPGES2 was apparent within 24 h, reaching 95% over the 72 h and was persistent for at least 120 h. The methods developed resulted in rapid and persistent knockdown in L. salmonis suitable for studies in the different stadia.; E. M. Campbell...

Analyse der biologischen Funktion des Parkinson assoziierten Proteins LRRK2 in Knockdown Modellen; Analysis of the biological function of the Parkinson’s disease associated protein LRRK2 in knockdown models

Häbig, Karina
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
Português
Relevância na Pesquisa
26.08%
Das Parkinson-Syndrom (PS) ist die zweithäufigste neurodegenerative Erkrankung. Aus diesem Grund ist die Erforschung ihrer Pathogenese von zentraler Bedeutung. In dieser Arbeit wurde die biologische Funktion der Leucine-rich repeat kinase 2 (LRRK2) untersucht. Dieses Protein, welches 2004 identifiziert wurde, ist nicht nur verantwortlich für 5-6% der autosomal dominanten, sondern auch für 1-2% der sporadischen Parkinson-Syndrome. Diese Arbeit beschreibt erstmals die gesamtgenomischen Auswirkungen des Verlustes von LRRK2 in humanen dopaminergen Zellen und gibt damit einen Einblick in LRRK2-abhängige Signalkaskaden. Dieser Verlust („Knockdown“) konnte auf RNA- und Proteinebene mit Hilfe von RNA-Interferenz erreicht werden. Die Analyse der Gene und Signalkaskaden, welche durch den Verlust von LRRK2 differentiell reguliert werden, führt in dieser Arbeit zu der Betrachtung von drei grundlegenden Fragestellungen. Apoptoseprozesse werden mit der Pathogenese des PS in Zusammenhang gebracht. Aus diesem Grund befasst sich die erste Fragestellung dieser Arbeit mit dem Einfluss von LRRK2 auf Apoptose-Signalkaskaden. Das gesamtgenomische Expressionsprofil des humanen Zellkulturmodells zeigt einen deutlichen Einfluss des LRRK2-Verlustes auf p53-abhängige Signalkaskaden. Dabei ist p53 ein entscheidender Regulator der Apoptoseprozesse. Auch die Expressionsanalyse von Gehirnen LRRK2-defizienter Tiere bestätigt dieses Ergebnis. Die anschließende funktionelle Analyse im humanen LRRK2-Knockdown-Modell verdeutlicht eine antiapoptotische Wirkung des LRRK2-Verlustes...