Lysozyme-coated nanoparticles for active uptake and delivery of synthetic RNA and plasmid-encoded genes in plants.

Nanoparticle-mediated delivery of nucleic acids and proteins into intact plants has the potential to modify metabolic pathways and confer desirable traits in crops. Here we show that layered double hydroxide (LDH) nanosheets coated with lysozyme are actively taken up into the root tip, root hairs and lateral root junctions by endocytosis, and translocate via an active membrane trafficking pathway in plants. Lysozyme coating enhanced nanosheet uptake by (1) loosening the plant cell wall and (2) stimulating the expression of endocytosis and other membrane trafficking genes.

Enhancing plant biotechnology by nanoparticle delivery of nucleic acids.

Plant biotechnology plays a crucial role in developing modern agriculture and plant science research. However, the delivery of exogenous genetic material into plants has been a long-standing obstacle. Nanoparticle-based delivery systems are being established to address this limitation and are proving to be a feasible, versatile, and efficient approach to facilitate the internalization of functional RNA and DNA by plants.

RNA-Based Control of Fungal Pathogens in Plants.

Our duty to conserve global natural ecosystems is increasingly in conflict with our need to feed an expanding population. The use of conventional pesticides not only damages the environment and vulnerable biodiversity but can also still fail to prevent crop losses of 20-40% due to pests and pathogens. There is a growing call for more ecologically sustainable pathogen control measures.

Miniature Inverted-Repeat Transposable Elements: Small DNA Transposons That Have Contributed to Plant Gene Evolution.

Angiosperms form the largest phylum within the Plantae kingdom and show remarkable genetic variation due to the considerable difference in the nuclear genome size of each species. Transposable elements (TEs), mobile DNA sequences that can amplify and change their chromosome position, account for much of the difference in nuclear genome size between individual angiosperm species. Considering the dramatic consequences of TE movement, including the complete loss of gene function, it is unsurprising that the angiosperms have developed elegant molecular strategies to control TE amplification and movement.

() Is Essential for Cell Proliferation and Cell Differentiation in Tomato.

Most flowering plant species contain at least two copies of the () gene with the encoded DEM proteins lacking homology to proteins of known biochemical function. In tomato (; ), stable mutations in the locus result in shoot and root meristem defects with the mutant failing to progress past the cotyledon stage of seedling development. Generation of a () transformant line in tomato allowed for the characterization of gene function past the seedling stage of vegetative development with plants displaying a range of leaf development abnormalities.

Clay nanoparticles efficiently deliver small interfering RNA to intact plant leaf cells.

RNA interference is triggered in plants by the exogenous application of double-stranded RNA or small interfering RNA (siRNA) to silence the expression of target genes. This approach can potentially provide insights into metabolic pathways and gene function and afford plant protection against viruses and other plant pathogens. However, the effective delivery of biomolecules such as siRNA into plant cells is difficult because of the unique barrier imposed by the plant cell wall.

Tospoviruses Induce Small Interfering RNAs Targeting Viral Sequences and Endogenous Transcripts in Solanaceous Plants.

Tospoviruses infect numerous crop species worldwide, causing significant losses throughout the supply chain. As a defence mechanism, plants use RNA interference (RNAi) to generate virus-derived small-interfering RNAs (vsiRNAs), which target viral transcripts for degradation. Small RNA sequencing and in silico analysis of capsicum and infected by tomato spotted wilt virus (TSWV) or capsicum chlorosis virus (CaCV) demonstrated the presence of abundant vsiRNAs, with host-specific differences evident for each pathosystem.

Sheet-like clay nanoparticles deliver RNA into developing pollen to efficiently silence a target gene.

Topical application of double-stranded RNA (dsRNA) can induce RNA interference (RNAi) and modify traits in plants without genetic modification. However, delivering dsRNA into plant cells remains challenging. Using developing tomato (Solanum lycopersicum) pollen as a model plant cell system, we demonstrate that layered double hydroxide (LDH) nanoparticles up to 50 nm in diameter are readily internalized, particularly by early bicellular pollen, in both energy-dependent and energy-independent manners and without physical or chemical aids.

DEFECTIVE EMBRYO AND MERISTEMS genes are required for cell division and gamete viability in Arabidopsis.

The DEFECTIVE EMBRYO AND MERISTEMS 1 (DEM1) gene encodes a protein of unknown biochemical function required for meristem formation and seedling development in tomato, but it was unclear whether DEM1's primary role was in cell division or alternatively, in defining the identity of meristematic cells. Genome sequence analysis indicates that flowering plants possess at least two DEM genes. Arabidopsis has two DEM genes, DEM1 and DEM2, which we show are expressed in developing embryos and meristems in a punctate pattern that is typical of genes involved in cell division.

Contrasting epigenetic control of transgenes and endogenous genes promotes post-transcriptional transgene silencing in Arabidopsis.

Transgenes that are stably expressed in plant genomes over many generations could be assumed to behave epigenetically the same as endogenous genes. Here, we report that whereas the histone H3K9me2 demethylase IBM1, but not the histone H3K4me3 demethylase JMJ14, counteracts DNA methylation of Arabidopsis endogenous genes, JMJ14, but not IBM1, counteracts DNA methylation of expressed transgenes. Additionally, JMJ14-mediated specific attenuation of transgene DNA methylation enhances the production of aberrant RNAs that readily induce systemic post-transcriptional transgene silencing (PTGS).

Post-transcriptional gene silencing triggers dispensable DNA methylation in gene body in Arabidopsis.

Spontaneous post-transcriptional silencing of sense transgenes (S-PTGS) is established in each generation and is accompanied by DNA methylation, but the pathway of PTGS-dependent DNA methylation is unknown and so is its role. Here we show that CHH and CHG methylation coincides spatially and temporally with RDR6-dependent products derived from the central and 3' regions of the coding sequence, and requires the components of the RNA-directed DNA methylation (RdDM) pathway NRPE1, DRD1 and DRM2, but not CLSY1, NRPD1, RDR2 or DCL3, suggesting that RDR6-dependent products, namely long dsRNAs and/or siRNAs, trigger PTGS-dependent DNA methylation. Nevertheless, none of these RdDM components are required to establish S-PTGS or produce a systemic silencing signal.

Fast Feedback Inhibition of Adrenocorticotropic Hormone Secretion by Endogenous Cortisol in Humans.

Background: Using high-frequency blood sampling, we demonstrate glucocorticoid fast feedback (FF) mediated by endogenous cortisol in 6 normal humans.

Methods: We stimulated adrenocorticotropic hormone (ACTH) secretion by ovine corticotropin-releasing hormone (oCRH) with the experimental paradigm in which a high-frequency blood sampling was designed for plasma ACTH and cortisol determinations.

Results: We saw previously unrecognized variability in the timing of key events such as onsets of ACTH and cortisol secretion, onset and offset of FF, and in FF duration.

Evolution and Diversification of Small RNA Pathways in Flowering Plants.

Small regulatory RNAs guide gene silencing at the DNA or RNA level through repression of complementary sequences. The two main forms of small RNAs are microRNA (miRNA) and small interfering RNA (siRNAs), which are generated from the processing of different forms of double-stranded RNA (dsRNA) precursors. These two forms of small regulatory RNAs function in distinct but overlapping gene silencing pathways in plants.

RNA-Dependent Epigenetic Silencing Directs Transcriptional Downregulation Caused by Intronic Repeat Expansions.

Transcriptional downregulation caused by intronic triplet repeat expansions underlies diseases such as Friedreich's ataxia. This downregulation of gene expression is coupled with epigenetic changes, but the underlying mechanisms are unknown. Here, we show that an intronic GAA/TTC triplet expansion within the IIL1 gene of Arabidopsis thaliana results in accumulation of 24-nt short interfering RNAs (siRNAs) and repressive histone marks at the IIL1 locus, which in turn causes its transcriptional downregulation and an associated phenotype.

Exposure to General Anesthesia and Risk of Dementia: A Nationwide Population-Based Cohort Study.

Background: There is a growing concern that general anesthesia could increase the risk of dementia. However, the relationship between anesthesia and subsequent dementia is still undetermined.

Objective: To determine whether the risk of dementia increases after exposure to general anesthesia.

SCRAM: a pipeline for fast index-free small RNA read alignment and visualization.

Summary: Small RNAs play key roles in gene regulation, defense against viral pathogens and maintenance of genome stability, though many aspects of their biogenesis and function remain to be elucidated. SCRAM (Small Complementary RNA Mapper) is a novel, simple-to-use short read aligner and visualization suite that enhances exploration of small RNA datasets.

Availability And Implementation: The SCRAM pipeline is implemented in Go and Python, and is freely available under MIT license.

Extrapyramidal Signs and Risk of Progression from Mild Cognitive Impairment to Dementia: A Clinical Research Center for Dementia of South Korea Study.

Objective: Extrapyramidal signs (EPS) are common in patients with mild cognitive impairment (MCI). However, few studies have assessed the effect of EPS on the clinical course of MCI. We aimed to evaluate whether patients with EPS show more frequent progression from MCI to Alzheimer's disease (AD) and to other types of dementia.

A Genetic Screen for Impaired Systemic RNAi Highlights the Crucial Role of DICER-LIKE 2.

Posttranscriptional gene silencing (PTGS) of transgenes involves abundant 21-nucleotide small interfering RNAs (siRNAs) and low-abundance 22-nucleotide siRNAs produced from double-stranded RNA (dsRNA) by DCL4 and DCL2, respectively. However, DCL2 facilitates the recruitment of RNA-DEPENDENT RNA POLYMERASE 6 (RDR6) to ARGONAUTE 1-derived cleavage products, resulting in more efficient amplification of secondary and transitive dsRNA and siRNAs. Here, we describe a reporter system where RDR6-dependent PTGS is initiated by restricted expression of an inverted-repeat dsRNA specifically in the Arabidopsis () root tip, allowing a genetic screen to identify mutants impaired in RDR6-dependent systemic PTGS.

Induction of virus resistance by exogenous application of double-stranded RNA.

Exogenous application of double-stranded RNA (dsRNA) for virus resistance in plants represents a very attractive alternative to virus resistant transgenic crops or pesticides targeting virus vectors. However, the instability of dsRNA sprayed onto plants is a major challenge as spraying naked dsRNA onto plants provides protection against homologous viruses for only 5 days. Innovative approaches, such as the use of nanoparticles as carriers of dsRNA for improved stability and sustained release, are emerging as key disruptive technologies.