259 research outputs found

    Influence of viral genes on the cell-to-cell spread of RNA silencing

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    The turnip crinkle virus-based vector TCV–GFPDCP had been devised previously to study cell-to-cell and long-distance spread of virus-induced RNA silencing. TCV–GFPDCP, which had been constructed by replacing the coat protein (CP) gene with a green fluorescent protein (GFP) coding sequence, was able to induce RNA silencing in single epidermal cells, from which RNA silencing spread from cell-to-cell. Using this unique local silencing assay together with mutagenesis analysis, two TCV genes, p8 and p9, which were involved in the intercellular spread of virus-induced RNA silencing, were identified. TCV–GFPDCP and its p8- or p9-mutated derivatives, TCVmp8–GFPDCP and TCVmp9–GFPDCP, replicated efficiently but were restricted to single Nicotiana benthamiana epidermal cells. TCV–GFPDCP, TCVmp8–GFPDCP, or TCVmp9–GFPDCP was able to initiate RNA silencing that targeted and degraded recombinant viral RNAs in inoculated leaves of the GFP-expressing N. benthamiana line 16c. However, cell-to-cell spread of silencing to form silencing foci was triggered only by TCV–GFPDCP. Non-replicating TCVmp88–GFPDCP and TCVmp28mp88–GFPDCP with dysfunctional replicase genes, and single-stranded gfp RNA did not induce RNA silencing. Transient expression of the TCV p9 protein could effectively complement TCVmp9–GFPDCP to facilitate intercellular spread of silencing. These data suggest that the plant cellular trafficking machinery could hijack functional viral proteins to permit cell-to-cell movement of RNA silencing

    Vibration characteristics and environmental responses of different vehicle-track-ballast coupling systems in subway operation

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    The vibration characteristics of two ballast beds are analyzed in this study from five aspects including the amplitude-frequency characteristic curve of foundation reaction. This study also shows that the maximum ground Z vibration level caused by a normal monolithic ballast bed structure is 75 dB. The range of its vibration influence during daytime is approximately 30 m. The maximum ground Z vibration level caused by a rubber floating slab track structure is 52 dB, whereas that caused by a steel spring floating slab track structure is 57 dB. The maximum damping amount in horizontal speed of a rubber floating slab track structure is 74 %, whereas the reduction of vertical ground vibration speed and acceleration is 92 % and 93 %, respectively. The reduction in Z level is 37 %. The horizontal speed reduction in a steel spring floating slab track structure is 71 %, whereas the reduction of ground vertical vibration speed and acceleration is 83 % and 84 %, respectively. The reduction in Z level is 29 %

    A tomato HD-Zip homeobox protein, LeHB-1, plays an important role in floral organogenesis and ripening

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    Ethylene is required for climacteric fruit ripening. Inhibition of ethylene biosynthesis genes, 1-aminocyclopropane-1-carboxylate (ACC) synthase and ACC oxidase, prevents or delays ripening, but it is not known how these genes are modulated during normal development. LeHB-1, a previously uncharacterized tomato homeobox protein, was shown by gel retardation assay to interact with the promoter of LeACO1, an ACC oxidase gene expressed during ripening. Inhibition of LeHB-1 mRNA accumulation in tomato fruit, using virus-induced gene silencing, greatly reduced LeACO1 mRNA levels, and inhibited ripening. Conversely, ectopic overexpression of LeHB-1 by viral delivery to developing flowers elsewhere on injected plants triggered altered floral organ morphology, including production of multiple flowers within one sepal whorl, fusion of sepals and petals, and conversion of sepals into carpel-like structures that grew into fruits and ripened. Our findings suggest that LeHB-1 is not only involved in the control of ripening but also plays a critical role in floral organogenesis

    Virus-induced gene complementation reveals a transcription factor network in modulation of tomato fruit ripening

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    Plant virus technology, in particular virus-induced gene silencing, is a widely used reverse- and forward-genetics tool in plant functional genomics. However the potential of virus technology to express genes to induce phenotypes or to complement mutants in order to understand the function of plant genes is not well documented. Here we exploit Potato virus X as a tool for virus-induced gene complementation (VIGC). Using VIGC in tomato, we demonstrated that ectopic viral expression of LeMADS-RIN, which encodes a MADS-box transcription factor (TF), resulted in functional complementation of the non-ripening rin mutant phenotype and caused fruits to ripen. Comparative gene expression analysis indicated that LeMADS-RIN up-regulated expression of the SBP-box (SQUAMOSA promoter binding protein-like) gene LeSPL-CNR, but down-regulated the expression of LeHB-1, an HD-Zip homeobox TF gene. Our data support the hypothesis that a transcriptional network may exist among key TFs in the modulation of fruit ripening in tomato

    Circular RNA circNOL10 Inhibits Lung Cancer Development by Promoting SCLM1-Mediated Transcriptional Regulation of the Humanin Polypeptide Family

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    circNOL10 is a circular RNA expressed at low levels in lung cancer, though its functions in lung cancer remain unknown. Here, the function and molecular mechanism of circNOL10 in lung cancer development are investigated using in vitro and in vivo studies, and it is shown that circNOL10 significantly inhibits the development of lung cancer and that circNOL10 expression is co‐regulated by methylation of its parental gene Pre‐NOL10 and by splicing factor epithelial splicing regulatory protein 1 (ESRP1). circNOL10 promotes the expression of transcription factor sex comb on midleg‐like 1 (SCML1) by inhibiting transcription factor ubiquitination and thus also affects regulation of the humanin (HN) polypeptide family by SCML1. circNOL10 also affects mitochondrial function through regulating the humanin polypeptide family and affecting multiple signaling pathways, ultimately inhibiting cell proliferation and cell cycle progression, and promoting the apoptosis of lung cancer cells, thereby inhibiting lung cancer development. This study investigates the functions and molecular mechanisms of circNOL10 in the development of lung cancer and reveals its involvement in the transcriptional regulation of the HN polypeptide family by SCML1. The results also demonstrate the inhibitory effect of HN on lung cancer cells growth. These findings may identify novel targets for the molecular therapy of lung cancer

    Mobile Flowering Locus T RNA – Biological Relevance and Biotechnological Potential

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    Many systemically mobile mRNAs have been revealed in phloem. However, very few of them have been found to be of clear signaling functions. One of such rare examples is the mobile Flowering locus T (FT) mRNA despite the continuous debate about its mobility and biological relevance to the control of flowering time in plants. Nevertheless, accumulating evidence supports the notion of the long-distance movement of FT mRNA from leaf to shoot apex meristem and its role in flowering. In this review, we discuss the discovery of florigenic FT, the initial debate on long-distance movement of FT mRNA, emerging evidence to prove its mobility, and the use of mobile FT mRNA to generate heritable transgenerational gene editing in plants. We elaborate on evidence from virus-based RNA mobility assay, plant grafting, RNA with fluorescent protein labeling, and CRISPR/Cas9 gene-editing technology, to demonstrate that the FT mRNA besides the FT protein can move systemically and function as an integral component of the florigenic signal in flowering. We also propose a model to prompt further research on the molecular mechanism underlying the long-distance movement of this important mobile signaling RNA in plants

    Adipocyte CREB Promotes Insulin Resistance in Obesity

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    SummaryIncreases in adiposity trigger metabolic and inflammatory changes that interfere with insulin action in peripheral tissues, culminating in beta cell failure and overt diabetes. We found that the cAMP Response Element Binding protein (CREB) is activated in adipose cells under obese conditions, where it promotes insulin resistance by triggering expression of the transcriptional repressor ATF3 and thereby downregulating expression of the adipokine hormone adiponectin as well as the insulin-sensitive glucose transporter 4 (GLUT4). Transgenic mice expressing a dominant-negative CREB transgene in adipocytes displayed increased whole-body insulin sensitivity in the contexts of diet-induced and genetic obesity, and they were protected from the development of hepatic steatosis and adipose tissue inflammation. These results indicate that adipocyte CREB provides an early signal in the progression to type 2 diabetes

    Patterns of Convergence and Divergence Between Bipolar Disorder Type I and Type II: Evidence From Integrative Genomic Analyses

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    Aim: Genome-wide association studies (GWAS) analyses have revealed genetic evidence of bipolar disorder (BD), but little is known about the genetic structure of BD subtypes. We aimed to investigate the genetic overlap and distinction of bipolar type I (BD I) & type II (BD II) by conducting integrative post-GWAS analyses. Methods: We utilized single nucleotide polymorphism (SNP)-level approaches to uncover correlated and distinct genetic loci. Transcriptome-wide association analyses (TWAS) were then approached to pinpoint functional genes expressed in specific brain tissues and blood. Next, we performed cross-phenotype analysis, including exploring the potential causal associations between two BD subtypes and lithium responses and comparing the difference in genetic structures among four different psychiatric traits. Results: SNP-level evidence revealed three genomic loci, SLC25A17, ZNF184, and RPL10AP3, shared by BD I and II, and one locus (MAD1L1) and significant gene sets involved in calcium channel activity, neural and synapsed signals that distinguished two subtypes. TWAS data implicated different genes affecting BD I and II through expression in specific brain regions (nucleus accumbens for BD I). Cross-phenotype analyses indicated that BD I and II share continuous genetic structures with schizophrenia and major depressive disorder, which help fill the gaps left by the dichotomy of mental disorders. Conclusion: These combined evidences illustrate genetic convergence and divergence between BD I and II and provide an underlying biological and trans-diagnostic insight into major psychiatric disorders
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