159 research outputs found
Development of a simple index to predict benefit and satisfaction from amplification
The purpose of this study was to evaluate the use of non-audiological patient-based variables; amount of bother, importance of improved hearing, and expectations, as reliable predictors of benefit and satisfaction from amplification. Study findings were then used to develop two initial prognostic indices
Cellular pathways for viral transport through plasmodesmata
Plant viruses use plasmodesmata (PD) to spread infection between cells and systemically. Dependent on viral species, movement through PD can occur in virion or non-virion form, and requires different mechanisms for targeting and modification of the pore. These mechanisms are supported by viral movement proteins and by other virus-encoded factors that interact among themselves and with plant cellular components to facilitate virus movement in a coordinated and regulated fashio
Transcriptome analysis of the Populus trichocarpa-Rhizophagus irregularis Mycorrhizal Symbiosis: Regulation of Plant and Fungal Transportomes under Nitrogen Starvation
Nutrient transfer is a key feature of the arbuscular mycorrhizal (AM) symbiosis. Valuable mineral nutrients are transferred from the AM fungus to the plant, increasing its fitness and productivity, and, in exchange, the AM fungus receives carbohydrates as an energy source from the plant. Here, we analyzed the transcriptome of the Populus trichocarpa-Rhizophagus irregularis symbiosis using RNA-sequencing of non-mycorrhizal or mycorrhizal fine roots, with a focus on the effect of nitrogen (N) starvation. In R. irregularis, we identified 1,015 differentially expressed genes, whereby N starvation led to a general induction of gene expression. Genes of the functional classes of cell growth, membrane biogenesis and cell structural components were highly abundant. Interestingly, N starvation also led to a general induction of fungal transporters, indicating increased nutrient demand upon N starvation. In non-mycorrhizal P. trichocarpa roots, 1,341 genes were differentially expressed under N starvation. Among the 953 down-regulated genes in N starvation, most were involved in metabolic processes including amino acids, carbohydrate and inorganic ion transport, while the 342 up-regulated genes included many defense-related genes. Mycorrhization led to the up-regulation of 549 genes mainly involved in secondary metabolite biosynthesis and transport; only 24 genes were down-regulated. Mycorrhization specifically induced expression of three ammonium transporters and one phosphate transporter, independently of the N conditions, corroborating the hypothesis that these transporters are important for symbiotic nutrient exchange. In conclusion, our data establish a framework of gene expression in the two symbiotic partners under high-N and low-N conditions
Fluorescent Tobacco mosaic virus-Derived Bio-Nanoparticles for Intravital Two-Photon Imaging
Multi-photon intravital imaging has become a powerful tool to investigate the healthy and diseased brain vasculature in living animals. Although agents for multi-photon fluorescence microscopy of the microvasculature are available, issues related to stability, bioavailability, toxicity, cost or chemical adaptability remain to be solved. In particular, there is a need for highly fluorescent dyes linked to particles that do not cross the blood brain barrier (BBB) in brain diseases like tumor or stroke to estimate the functional blood supply. Plant virus particles possess a number of distinct advantages over other particles, the most important being the multi-valency of chemically addressable sites on the particle surface. This multi-valency, together with biological compatibility and inert nature, makes plant viruses ideal carriers for in vivo imaging agents. Here, we show that the well-known Tobacco mosaic virus is a suitable nanocarrier for two-photon dyes and for intravital imaging of the mouse brain vasculature
Specific Impact of Tobamovirus Infection on the Arabidopsis Small RNA Profile
Tobamoviruses encode a silencing suppressor that binds small RNA (sRNA) duplexes
in vitro and supposedly in vivo to
counteract antiviral silencing. Here, we used sRNA deep-sequencing combined with
transcriptome profiling to determine the global impact of tobamovirus infection
on Arabidopsis sRNAs and their mRNA targets. We found that
infection of Arabidopsis plants with Oilseed rape
mosaic tobamovirus causes a global size-specific enrichment of
miRNAs, ta-siRNAs, and other phased siRNAs. The observed patterns of sRNA
enrichment suggest that in addition to a role of the viral silencing suppressor,
the stabilization of sRNAs might also occur through association with unknown
host effector complexes induced upon infection. Indeed, sRNA enrichment concerns
primarily 21-nucleotide RNAs with a 5′-terminal guanine. Interestingly,
ORMV infection also leads to accumulation of novel miRNA-like sRNAs from miRNA
precursors. Thus, in addition to canonical miRNAs and miRNA*s, miRNA
precursors can encode additional sRNAs that may be functional under specific
conditions like pathogen infection. Virus-induced sRNA enrichment does not
correlate with defects in miRNA-dependent ta-siRNA biogenesis nor with global
changes in the levels of mRNA and ta-siRNA targets suggesting that the enriched
sRNAs may not be able to significantly contribute to the normal activity of
pre-loaded RISC complexes. We conclude that tobamovirus infection induces the
stabilization of a specific sRNA pool by yet unknown effector complexes. These
complexes may sequester viral and host sRNAs to engage them in yet unknown
mechanisms involved in plant:virus interactions
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