MicroRNA390-Directed TAS3 Cleavage Leads to the Production of tasiRNA-ARF3/4 During Somatic Embryogenesis in Dimocarpus longan Lour

Trans-acting short-interfering RNAs (tasiRNAs) originate from TAS3 families through microRNA (miRNA) 390-guided cleavage of primary transcripts and target auxin response factors (ARF3/-4), which are involved in the normal development of lateral roots and flowers in plants. However, their roles in embryo development are still unclear. Here, the pathway miR390-TAS3-ARF3/-4 was identified systematically for the first time during somatic embryo development in Dimocarpus longan. We identified the miR390 primary transcript and promoter. The promoter contained cis-acting elements responsive to stimuli such as light, salicylic acid, anaerobic induction, fungal elicitor, circadian control and heat stress. The longan TAS3 transcript, containing two miR390-binding sites, was isolated; the miR390- guided cleavage site located near the 3' end of the TAS3 transcript was verified. Eight TAS3-tasiRNAs with the 21-nucleotide phase were found among longan small RNA data, further confirming that miR390-directed TAS3 cleavage leads to the production of tasiRNA in longan. Among them, TAS3_5'D5+ and 5'D6+ tasiRNAs were highly abundant, and verified to target ARF3 and -4, implying that miR390-guided TAS3 cleavage with 21-nucleotide phase leading to the production of tasiRNA-ARF is conserved in plants. Pri-miR390 was highly expressed in friable-embryogenic callus (EC), and less expressed in incomplete compact pro-embryogenic cultures,while miR390 showed its lowest expression in EC and highest expression in torpedo-shaped embryo. DlTAS3 and DlARF4 both exhibited their lowest expressions in EC, and reached their peaks in the globular embryos stage, which were mainly inversely proportional to the expression of miR390, especially at the GE to CE stages. While DlARF3 showed little variation from the EC to torpedo-shaped embryos stages, and exhibited its lowest expression in the cotyledonary embryos stage. There was a general lack of correlation between the expressions of DlARF3 and miR390. In addition, miR390, DlTAS3, DlARF3, and -4 were up-regulated by 2,4-D in a concentration-dependent manner. They were also preferentially expressed in roots, pulp, and seeds of ‘Sijimi’ longan, implying their extended roles in the development of longan roots and fruit. This study provided insights into a possible role of miR390-tasiRNAs-ARF in plant somatic embryo development

Comparative transcriptome analyses reveal a special glucosinolate metabolism mechanism in Brassica alboglabra sprouts

Brassica sprouts contain abundant phytochemicals, especially glucosinolates (GSs). Various methods have been used to enhance GS content in sprouts. However, the molecular basis of GS metabolism in sprouts remains an open question. Here we employed RNA-seq analysis to compare the transcriptomes of high-GS (JL-08) and low-GS (JL-09) Brassica alboglabra sprouts. Paired-end Illumina RNA-seq reads were generated and mapped to the B. oleracea reference genome. The differentially expressed genes were analyzed between JL-08 and JL-09. Among these, 1,477 genes were up-regulated and 1,239 down-regulated in JL-09 compared with JL-08. Enrichment analysis of these differentially expressed genes showed that the GS biosynthesis had the smallest enrichment factor and the highest Q value of all metabolic pathways in Kyoto Encyclopedia of Genes and Genomes database, indicating the main metabolic difference between JL-08 and JL-09 is the GS biosynthetic pathway. Thirty-seven genes of the sequenced data were annotated as putatively involved in GS biosynthesis, degradation and regulation, of which 11 were differentially expressed in JL-08 and JL-09. The expression level of GS degradation enzyme myrosinase in high-GS JL-08 was lower compared with low-GS JL-09. Surprisingly, in high-GS JL-08, the expression levels of GS biosynthesis genes were also lower than those in low-GS JL-09. As the GS contents in sprouts are determined by dynamic equilibrium of seed stored GS mobilization, de novo synthesis, degradation, and extra transport, the result of this study leads us to suggest that efforts to increase GS content should focus on either raising GS content in seeds or decreasing myrosinase activity, rather than improving the expression level of GS biosynthesis genes in sprouts

Computational fluid dynamics applied to mining engineering: a review

This paper provides a review of computational fluid dynamics (CFD) applications in mining engineering, with particular focus on mine ventilation-related flow problems. The basic principles of CFD are reviewed and six turbulence models commonly used are discussed with some examples of their application and guidelines on choosing an appropriate turbulence model. General modelling procedures are also provided with particular emphasis on mesh independence study and CFD validation methods, which can further improve the accuracy of a model. CFD applications in mining engineering research and design areas are reviewed, which illustrate the success of CFD and highlight challenging issues. It is expected that more CFD research will be carried out to solve problems in mining engineering, and the potential benefits from the simulations are enormous if proper modelling procedures are followed and modern computational approaches are implemented

Characterization of Red Sand Dust Pollution Control Performance via Static and Dynamic Laboratorial Experiments when Applying Polymer Stabilizers

Red sand dust pollution is of great concern for its occupational and environmental detriments. The current remediation technique includes water spray and non-traditional stabilization via the application of polymer stabilizers. The dust erosion resistance plays a significant role in quantifying the effectiveness of red sand dust suppression. The aim of this paper is to evaluate the reliability and accuracy of five static and dynamic laboratorial methods that are commonly utilized to quantify the dust erosion resistance in the presence of polymers in previous studies, which are wind tunnel simulation, dynamic viscosity test, crust thickness test, penetration resistance test, and unconfined compressive strength test. The advantages and shortcomings of these methods were comprehensively demonstrated. The results illustrated that the penetration resistance test is the most reliable method in terms of the highest accuracy and relatively simpler operation. It also reveals excellent universality for effectively quantifying the dust erosion resistance of red sand with different particle sizes and for different polymers with various concentrations, while the rest of the methods failed to identify. The application of polymers contributes to improved dust erosion resistance for longer crust failure time, higher solution dynamic viscosity and crust penetration resistance, and higher unconfined compressive strength of rending sand samples. PAM outperformed guar gum and xanthan gum on the base of polymer ionicity and molecular weight. This study offers a better understanding in guiding the selection of optimum evaluation methods and polymers for the study of bauxite residue dust control

Effect of Synergistic Aging on Bauxite Residue Dust Reduction Performance via the Application of Colloids, an Orthogonal Design-Based Study

The application of polymer colloids is a promising approach for bauxite residue dust pollution control. However, due to the existence of synergistic aging, the efficiency of colloid dynamic viscosity to predict the dust control performance of bauxite residue is unclear. Previous studies were also rarely performed under synergistic aging conditions. Thus, this paper investigates the relationship between colloids’ viscosity and dust control performance under synergistic aging modes. Results illustrated that the binary colloid achieved better dust control performance than unitary colloid for their higher viscosity and penetration resistance. For both unitary and binary colloid, higher viscosity results in better crust strength. A logarithmic relationship was found for viscosity and dust erosion resistance under unitary aging. However, Only the dynamic viscosity of colloids in solid-liquid two-phase conditions, rather than dissolved in deionized water, can effectively predict the dust control performance under synergistic aging conditions

Reduction of Airborne Bauxite Residue Dust Pollution by Enhancing the Structural Stability Via the Application of Non-Traditional Stabilizers

Dust migration from bauxite residue causes serious occupational diseases and dramatic pollutions to on-site workers and the surrounding environment. In order to investigate the enhancement of mechanical properties and wind erosion behavior of non-traditional stabilizers in mitigating bauxite residue dust pollution, this paper carried out mechanical tests and wind tunnel simulations to reveal the independent and cooperative effect of mechanical properties on dust control performance and the effect of particle size on the accuracy of dust control evaluation strategy. Results illustrated the great significance of stabilizer concentration and particle size on both mechanical properties and dust control performance of treated samples. The penetration resistance was more accurate and effective in predicting dust control performance for lignosulfonate stabilizers, while unconfined compressive strength is more competitive as a key predicting index for polymer stabilizers. Particle size is critical to the evaluation of the dust control effect

Effect of Polymer Stabilizers-Viscosity on Red Sand Structure Strength and Dust Pollution Resistance

The utilization of polymer stabilizers is a promising method in mitigating bauxite residue (red sand) dust pollution. Its thickening property can effectively bind sand particles by constructing crusts to withstand wind erosion. Previous studies recommended the mixture of polymer solutions for a better dust control performance. However, limited references discussed the effects their viscosity on the structure strength of formed crusts and the final erosion resistance. The environmental adaptability of polymer mixtures was also rarely investigated. Thus, this paper investigates the effect of relationship between polymer viscosity, environmental adaptability and the final dust control performance. Results illustrated that the applied polymers have excellent ability in withstanding wetting, high temperature and long-term UV exposure, which indicates a broad applicability in wet conditions and desert regions. For both single cationic polymers or polymer mixtures containing cationic polymers, higher solution viscosity resulted in better crust strength and dust erosion resistance when applied on red sand surface. Thus, the viscosity of polymer mixtures solution can effectively predict the structure strength of formed crust and the final erosion resistance of treated sand

Transcriptome Analysis Reveals Differentially Expressed Genes That Regulate Biosynthesis of the Active Compounds with Methyl Jasmonate in Rosemary Suspension Cells

To study the effects of Methyl jasmonates (MeJA) on rosemary suspension cells, the antioxidant enzymes’ change of activities under different concentrations of MeJA, including 0 (CK), 10 (M10), 50 (M50) and 100 μM MeJA (M100). The results demonstrated that MeJA treatments increased the activities of phenylalanine ammonla-lyase (PAL), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and polyphenol oxidase (PPO) and reduced the contents of hydrogen peroxide (H2O2) and malondialdehyde (MDA), thus accelerating the ROS scavenging. Comparative transcriptome analysis of different concentrations of MeJA showed that a total of 7836, 6797 and 8310 genes were differentially expressed in the comparisons of CKvsM10, CKvsM50, CKvsM100, respectively. The analysis of differentially expressed genes (DEGs) showed phenylpropanoid biosynthesis, vitamin B6, ascorbate and aldarate metabolism-related genes were significantly enriched. The transcripts of flavonoid and terpenoid metabolism pathways and plant hormone signal transduction, especially the jasmonic acid (JA) signal-related genes, were differentially expressed in CKvsM50 and CKvsM100 comparisons. In addition, the transcription factors (TFs), e.g., MYC2, DELLA, MYB111 played a key role in rosemary suspension cells under MeJA treatments. qRT-PCR of eleven DEGs showed a high correlation between the RNA-seq and the qRT-PCR result. Taken together, MeJA alleviated peroxidative damage of the rosemary suspension cells in a wide concentration range via concentration-dependent differential expression patterns. This study provided a transcriptome sequence resource responding to MeJA and a valuable resource for the genetic and genomic studies of the active compounds engineering in rosemary

Estimating Crown Structure Parameters of Moso Bamboo: Leaf Area and Leaf Angle Distribution

Both leaf area (LA) and leaf angle distribution are the most important eco-physiological measures of tree crowns. However, there are limited published investigations on the two parameters of Moso bamboo (Phyllostachys edulis (Carrière) J. Houz., abbreviated as MB). The aim of this study was to develop allometric equations for predicting crown LA of MB by taking the diameter at breast height (DBH) and tree height (H) as predictors and to investigate the leaf angle distribution of a MB crown based on direct leaf angle measurements. Data were destructively sampled from 29 MB crowns including DBH, H, biomass and the area of sampled leaves, biomass of total crown leaves, and leaf angles. The results indicate that (1) the specific leaf area (SLA) of a MB crown decreases from the bottom to the top; (2) the vertical LA distribution of MB crowns follow a “Muffin top” shape; (3) the LA of MB crowns show large variations, from 7.42 to 74.38 m2; (4) both DBH and H are good predictors in allometry-based LA estimations for a MB crown; (5) linear, exponential, and logarithmic regressions show similar capabilities for the LA estimations; (6) leaf angle distributions from the top to the bottom of a MB crown can be considered as invariant; and (7) the leaf angle distribution of a MB crown is close to the planophile case. The results provide an important tool to estimate the LA of MB on the standing scale based on DBH or H measurements, provide useful prior knowledge for extracting leaf area indexes of MB canopies from remote sensing-based observations, and, therefore, will potentially serve as a crucial reference for calculating carbon balances and other ecological studies of MB forests