Post-transcriptional control of miRNA abundance in Arabidopsis

MicroRNAs (miRNAs) are a class of small non-coding RNAs (small RNAs) that are 20–24nt in length and predominantly repress gene expression at post-transcriptional levels. They regulate many biological processes including development, metabolism and physiology. Numerous studies have revealed that the steady-state levels of miRNA are under sophisticated control to ensure their proper function. In this review, we summarize recent advances on regulation of miRNA processing and stability in plants

Uridylation of miRNAs by HEN1 SUPPRESSOR1 in \u3ci\u3eArabidopsis\u3c/i\u3e

HEN1-mediated 2′-O-methylation has been shown to be a key mechanism to protect plant microRNAs (miRNAs) and small interfering RNAs (siRNAs) as well as animal piwi-interacting RNAs (piRNAs) from degradation and 3′ terminal uridylation [1–8]. However, enzymes uridylating unmethylated miRNAs, siRNAs, or piRNAs in hen1 are unknown. In this study, a genetic screen identified a second-site mutation hen1 suppressor1-2 (heso1-2) that partially suppresses the morphological phenotypes of the hypomorphic hen1-2 allele and the null hen1-1 allele in Arabidopsis. HESO1 encodes a terminal nucleotidyl transferase that prefers to add untemplated uridine to the 3′ end of RNA, which is completely abolished by 2′-O-methylation. heso1-2 affects the profile of u-tailed miRNAs and siRNAs and increases the abundance of truncated and/or normal sized ones in hen1, which often results in increased total amount of miRNAs and siRNAs in hen1. In contrast, overexpressing HESO1 in hen1-2 causes more severe morphological defects and less accumulation of miRNAs. These results demonstrate that HESO1 is an enzyme uridylating unmethylated miRNAs and siRNAs in hen1. These observations also suggest that uridylation may destabilize unmethylated miRNAs through an unknown mechanism and compete with 3′-to-5′ exoribonuclease activities in hen1. This study shall have implications on piRNA uridylation in hen1 in animals

Small RNAs meet their targets: When methylation defends miRNAs from uridylation

Small RNAs are incorporated into Argonaute protein-containing complexes to guide the silencing of target RNAs in both animals and plants. The abundance of endogenous small RNAs is precisely controlled at multiple levels including transcription, processing and Argonaute loading. In addition to these processes, 3\u27 end modification of small RNAs, the topic of a research area that has rapidly evolved over the last several years, adds another layer of regulation of their abundance, diversity and function. Here, we review our recent understanding of small RNA 3\u27 end methylation and tailing

Rock-Cutting Performance Experimental Research of Particle Water Jet Based on Orthogonal Experimental Method

Particle Impact Drilling is an efficient drilling technology for deep-well hard formation which cuts rock mainly by high-speed spherical particle impacting rock with the help of hydraulic action and mechanical action. In order to determine main influence factors and their order of priority, the orthogonal experiment was designed and the experimental data was analyzed with both the general method and the variance method. The analysis indicates that the order of priority of the main influence factors of particle water jet rock-cutting performance is pump pressure ps, impacting range S, particle mass concentration ω, confining pressure P and particle diameter dp. Moreover, ps is highly important and S and ω are important. In addition, high ps, moderate S, moderate ω, moderate dp and low P could effectively promote particle water jet to impact and cut rocks. Key words: Deep hard formation; Particle impact drilling; Particle water jet; Rock-cutting performance; Orthogonal experiment method; Analysis of varianc

Distributed Solvers for Network Linear Equations with Scalarized Compression

In this paper, we study distributed solvers for network linear equations over a network with node-to-node communication messages compressed as scalar values. Our key idea lies in a dimension compression scheme including a dimension compressing vector that applies to individual node states to generate a real-valued message for node communication as an inner product, and a data unfolding step in the local computations where the scalar message is plotted along the subspace generated by the compression vector. We first present a compressed average consensus flow that relies only on such scalar communication, and show that exponential convergence can be achieved with well excited signals for the compression vector. We then employ such a compressed consensus flow as a fundamental consensus subroutine to develop distributed continuous-time and discrete-time solvers for network linear equations, and prove their exponential convergence properties under scalar node communications. With scalar communications, a direct benefit would be the reduced node-to-node communication channel capacity requirement for distributed computing. Numerical examples are presented to illustrate the effectiveness of the established theoretical results.Comment: 8 pages, 4 figure

CDC5, a DNA binding protein, positively regulates posttranscriptional processing and/or transcription of primary microRNA transcripts

CDC5 is a MYB-related protein that exists in plants, animals, and fungi. In Arabidopsis, CDC5 regulates both growth and immunity through unknown mechanisms. Here, we show that CDC5 from Arabidopsis positively regulates the accumulation of microRNAs (miRNAs), which control many biological processes including development and adaptations to environments in plants. CDC5 interacts with both the promoters of genes encoding miRNAs (MIR) and the DNA-dependent RNA polymerase II. As a consequence, lack of CDC5 reduces the occupancy of polymerase II at MIR promoters, as well as MIR promoter activities. In addition, CDC5 is associated with the DICER–LIKE1 complex, which generates miRNAs from their primary transcripts and is required for efficient miRNA production. These results suggest that CDC5 may have dual roles in miRNA biogenesis: functioning as a positive transcription factor of MIR and/or acting as a component of the DICER–LIKE1 complex to enhance primary miRNA processing

Two new species of the genus Laena (Coleoptera, Tenebrionidae, Lagriinae) from northern Sichuan in China based on morphological and molecular data

In this study, the Laena species from northern Sichuan Province were reviewed using a combination of molecular and morphological datasets. Three molecular methods for species delimitation were firstly used in the genus Laena to explore species boundaries. The results show that the number of morphospecies and putative species using Automatic Barcode Gap Discovery (ABGD) is consistent. Based on the results, two new species are described and illustrated: Laena mounigouica sp. nov. and Laena dentithoraxa sp. nov. New materials and distribution of 10 Laena species are also provided in this study. This work also provides valuable molecular data for species identification and phylogenetic analyses of the genus Laena and subfamily Lagriinae

Modeling Temperature, Frequency, and Strain Effects on the Linear Electro-Optic Coefficients of Ferroelectric Oxides

An electro-optic modulator offers the function of modulating the propagation of light in a material with electric field and enables seamless connection between electronics-based computing and photonics-based communication. The search for materials with large electro-optic coefficients and low optical loss is critical to increase the efficiency and minimize the size of electro-optic devices. We present a semi-empirical method to compute the electro-optic coefficients of ferroelectric materials by combining first-principles density-functional theory calculations with Landau-Devonshire phenomenological modeling. We apply the method to study the electro-optic constants, also called Pockels coefficients, of three paradigmatic ferroelectric oxides: BaTiO3, LiNbO3, and LiTaO3. We present their temperature-, frequency- and strain-dependent electro-optic tensors calculated using our method. The predicted electro-optic constants agree with the experimental results, where available, and provide benchmarks for experimental verification.Comment: 30 pages, 6 figures, 2 tables and 2 boxe