A single amino acid substitution in the R3 domain of GLABRA1 leads to inhibition of trichome formation in Arabidopsis without affecting its interaction with GLABRA3

GLABRA1 (GL1) is an R2R3 MYB transcription factor that regulates trichome formation in Arabidopsis by interacting with the bHLH transcription factor GLABRA3 (GL3) or ENHANCER OF GL3 (EGL3). The conserved [D/E]L×2 [R/K]×3L×6L×3R amino acid signature in the R3 domain of MYB proteins has been shown to be required for the interaction of MYBs with R/B‐like bHLH transcription factors. By using genetic and molecular analyses, we show that the glabrous phenotype in the nph4‐1 mutant is caused by a single nucleotide mutation in the GL1 gene, generating a Ser to Phe substitution (S92F) in the conserved [D/E]L×2[R/K]×3L×6L×3R amino acid signature of GL1. Activation of the integrated GL2p:GUS reporter gene in protoplasts by cotransfection of GL1 and GL3 or EGL3 was abolished by this GL1‐S92F substitution. However, GL1‐S92F interacted successfully with GL3 or EGL3 in protoplast transfection assays. Unlike VPGL1GL3, the fusion protein VPGL1‐S92FGL3 failed to activate the integrated GL2p:GUS reporter gene in transfected protoplasts. These results suggested that the S92 in the conserved [D/E]L×2 [R/K]×3L×6L×3R amino acid signature of GL1 is not essential for the interaction of GL1 and GL3, but may play a role in the binding of GL1 to the promoters of its target genes.The R2R3 MYB transcription factor GL1 is a key regulator of trichome formation in Arabidopsis. The conserved [D/E]L×2[R/K]×3L×6L×3R amino acid signature in the R3 domain is required for the interaction of MYBs with R/B‐like bHLH transcription factors. S92F amino acid substantiation in the conserved [D/E]L×2[R/K]×3L×6L×3R signature in GL1 lead to loss‐of‐function mutation of GL1. However, our results indicate that Ser92 residue is not required for the interaction of GL1 with bHLH transcription factor GL3 or EGL3, but may required for binding of GL1 to its target genes.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145310/1/pce12695_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145310/2/pce12695.pd

Arabidopsis Ovate Family Proteins, a Novel Transcriptional Repressor Family, Control Multiple Aspects of Plant Growth and Development

, AtOFP4 has been shown to regulate secondary cell wall formation by interact with KNOTTED1-LIKE HOMEODOMAIN PROTEIN 7 (KNAT7), and AtOFP5 has been shown to regulate the activity of a BEL1-LIKEHOMEODOMAIN 1(BLH1)-KNAT3 complex during early embryo sac development, but little is known about the function of other AtOFPs. genes may also have diverse functions in regulating plant growth and development. Further analysis suggested that AtOFP1 regulates cotyledon development in a postembryonic manner, and global transcript profiling revealed that it suppress the expression of many other genes.Our results showed that AtOFPs function as transcriptional repressors and they regulate multiple aspects of plant growth and development. These results provided the first overview of a previously unknown transcriptional repressor family, and revealed their possible roles in plant growth and development

Comprehensive analysis of single-repeat R3 MYB proteins in epidermal cell patterning and their transcriptional regulation in Arabidopsis

Abstract Background Single-repeat R3 MYB transcription factors are critical components of the lateral inhibition machinery that mediates epidermal cell patterning in plants. Sequence analysis of the Arabidopsis genome using the BLAST program reveals that there are a total of six genes, including TRIPTYCHON (TRY), CAPRICE (CPC), TRICHOMELESS1 (TCL1), and ENHANCER of TRY and CPC 1, 2, and 3 (ETC1, ETC2 and ETC3) encoding single-repeat R3 MYB transcription factors that are approximately 50% identical to one another at the amino acid level. Previous studies indicate that these single-repeat R3 MYBs regulate epidermal cell patterning. However, each of the previous studies of these single-repeat R3 MYBs has been limited to an analysis of only a subset of these six genes, and furthermore, they have limited their attention to epidermal development in only one or two of the organs. In addition, the transcriptional regulation of these single-repeat R3 MYB genes remains largely unknown. Results By analyzing multiple mutant lines, we report here that TCL1 functions redundantly with other single-repeat R3 MYB transcription factors to control both leaf trichome and root hair formation. On the other hand, ETC1 and ETC3 participate in controlling trichome formation on inflorescence stems and pedicles. Further, we discovered that single-repeat R3 MYBs suppress trichome formation on cotyledons and siliques, organs that normally do not bear any trichomes. By using Arabidopsis protoplast transfection assays, we found that all single-repeat R3 MYBs examined interact with GL3, and that GL1 or WER and GL3 or EGL3 are required and sufficient to activate the transcription of TRY, CPC, ETC1 and ETC3, but not TCL1 and ETC2. Furthermore, only ETC1's transcription was greatly reduced in the gl3 egl3 double mutants. Conclusion Our comprehensive analysis enables us to draw broader conclusions about the role of single-repeat R3 MYB gene family than were possible in the earlier studies, and reveals the genetic basis of organ-specific control of trichome formation. Our findings imply the presence of multiple mechanisms regulating the transcription of single-repeat R3 MYB genes, and provide new insight into the lateral inhibition mechanism that mediates epidermal cell patterning.http://deepblue.lib.umich.edu/bitstream/2027.42/116843/1/12870_2008_Article_289.pd

Application of electrical resistivity imaging to detection of hidden geological structures in a single roadway

Locating concealed geological structures in coal seams on both sides of a coal mine excavation roadway is of vital importance for safe production. Conventional electrical resistivity imaging methods mostly arrange observation systems on the roadway roof and floor, so they are inevitably deficient when it comes to detecting concealed geological structures in coal seams. According to the electric field distribution characteristics of artificial field sources for electrical resistivity imaging methods and utilizing the shielding of current by roadway cavities, this paper proposes the parallel coal seam detection method that arranges observation systems in coal seams on the roadway side to detect concealed geological structures in coal seams. On the basis of introducing the principles of consequent detection methods, this paper investigates the influence of roadway cavities on observation results and offers a method of correcting the influence of roadway cavities. In view of the geoelectric characteristics of typical concealed geological structures in working faces, this paper establishes numerical models to verify the feasibility of the parallel coal seam detection method. As indicated by the calculation results, the consequent pole–dipole (A-MN) observation system is the most ideal in terms of dividing the geoelectric interfaces of concealed geological structures in working faces, and its detection effect is influenced significantly by the coal seam thickness and the electric differences between surrounding rock and anomalous bodies. Coal seam resistivity slightly influences detection of the consequent pole–dipole system. According to practical application effects, the parallel coal seam detection method can solve the problem of detecting concealed geological structures in “single-roadway” working faces

A Study on Transient Electromagnetic Interpretation Method Based on the Seismic Wave Impedance Inversion Model

A comprehensive transient electromagnetic interpretation method based on seismic wave impedance inversion has been proposed according to the advantages of seismic and transient electromagnetic exploration methods to mitigate of hidden water inrush disasters in coalmines. Combined seismic wave impedance inversion results and resistivity logging data, the method was used to establish a geo-electric model. The stratigraphic horizon and the stratigraphic electrical characteristics were determined by the wave impedance inversion data and the resistivity logging data respectively. Furthermore, the structure and water-bearing property in the stratum were estimated by the analysis of the difference between the measured transient electromagnetic data and the calculated data from the forward model. The numerical calculation of the fault-containing model shows that the comprehensive interpretation method could determine the water-bearing capability of the fault as well as it tendency. An advantage of this new method is the effective avoidance of the influence of low-impedance overburden on the data interpretation. The practical application can accurately explain the location and the water-bearing property of the disaster-causing factors of the hidden water inrush in the coalmines

Pursuit Path Planning for Multiple Unmanned Ground Vehicles Based on Deep Reinforcement Learning

Path planning plays a crucial role in the execution of pursuit tasks for multiple unmanned ground vehicles (multi-UGVs). Although existing popular path-planning methods can achieve the pursuit goals, they suffer from some drawbacks such as long computation time and excessive path inflection points. To address these issues, this paper combines gradient descent and deep reinforcement learning (DRL) to solve the problem of excessive path inflection points from a path-smoothing perspective. In addition, the prioritized experience replay (PER) method is incorporated to enhance the learning efficiency of DRL. By doing so, the proposed model integrates PER, gradient descent, and a multiple-agent double deep Q-learning network (PER-GDMADDQN) to enable the path planning and obstacle avoidance capabilities of multi-UGVs. Experimental results demonstrate that the proposed PER-GDMADDQN yields superior performance in the pursuit problem of multi-UGVs, where the training speed and smoothness of the proposed method outperform other popular algorithms. As a result, the proposed method enables satisfactory path planning for multi-UGVs

A modified initial in-situ Stress Inversion Method based onFLAC3D with an engineering application

To improve the accuracy of an initial in-situstress field determined by inversion, we describe a modified initial in-situ stress inversion method that uses partialleast-squares regression based on FLAC3D. First, eachstress component is regressed to improve the fitting accuracyof locally abnormal stress regions, and then the relationshipbetween element stress and unbalanced nodeforce is analyzed according to the computational principlesof FLAC3D. The initial in-situ stresses obtained fromthese regression calculations are added to a numericalmodel, and the unbalanced node forces are recalculated.An external force equal to the recalculated unbalancednode force is then exerted on the node in the direction opposingthe original unbalanced node force to satisfy theequilibrium condition. For the in-situ stresses of elementsthat do not satisfy the strength conditions, they are modified by assuming the average stress is constant and reducingthe partial stress to satisfy the equilibrium andstrength conditions, which also resolves the unreasonabledistribution of the boundary nodal forces and results ingood regression estimates. A three-dimensional hypersurfacespline interpolation method is developed to calculatethe in-situ stress tensor at arbitrary coordinates. Finally,we apply this method to an underground engineeringproject, and the results are shown to agree well withthose obtained from field monitoring. Therefore, it is concludedthat this modified in-situ stress inversion methodcould effectively improve the fitting accuracy of locally abnormalstress regions

Assessment of a Concealed Karst Cave’s Influence on Karst Tunnel Stability: A Case Study of the Huaguoshan Tunnel, China

In order to assess a concealed karst cave’s influence on karst tunnel stability, an assessment model is proposed based on the analytic hierarchy process and a statistical analysis of relevant engineering projects. Major factors are studied and selected as impact factors of the assessment model based on a statistical analysis on a karst cave’ s development conditions (karst hydrogeological and engineering geological conditions), construction conditions, and controlling measures. A weight analysis of factors shows that the surrounding rock grade, supporting measurement, formation lithology, unfavorable geology, construction methods, blasting techniques, advanced geological forecast, and groundwater level are the main controlling factors of the tunnel stability when there is a concealed karst cave in the tunnel. Topography and geomorphology, attitude of rocks, monitoring measurement, strata combination, and interlayer fissures are the minor influence factors. Tunnel section shapes, in situ stress, and geological logging are the least important factors. The proposed method is successfully applied to the assessment of a concealed karst cave’s influence on the stability of the Huaguoshan Tunnel on the Enshi-Laifeng and Enshi-Qianjiang Expressways. The evaluation result agrees well with the construction site situation. In addition, the result provides good guidance with respect to the implementation of the treatment scheme and effectively avoids accidents in real-time

Metabolic engineering of fast-growing Vibrio natriegens for efficient pyruvate production

Abstract Background Pyruvate is a widely used value-added chemical which also serves as a hub of various metabolic pathways. The fastest-growing bacterium Vibrio natriegens is a promising chassis for synthetic biology applications with high substrate uptake rates. The aim of this study was to investigate if the high substrate uptake rates of V. natriegens enable pyruvate production at high productivities. Results Two prophage gene clusters and several essential genes for the biosynthesis of byproducts were first deleted. In order to promote pyruvate accumulation, the key gene aceE encoding pyruvate dehydrogenase complex E1 component was down-regulated to reduce the carbon flux into the tricarboxylic acid cycle. Afterwards, the expression of ppc gene encoding phosphoenolpyruvate carboxylase was fine-tuned to balance the cell growth and pyruvate synthesis. The resulting strain PYR32 was able to produce 54.22 g/L pyruvate from glucose within 16 h, with a yield of 1.17 mol/mol and an average productivity of 3.39 g/L/h. In addition, this strain was also able to efficiently convert sucrose or gluconate into pyruvate at high titers. Conclusion A novel strain of V. natriegens was engineered which was capable to provide higher productivity in pyruvate synthesis. This study lays the foundation for the biosynthesis of pyruvate and its derivatives in fast-growing V. natriegens