Rapid and accurate inversion of soil salinity is a key scientific problem that needs to be solved urgently. Due to the accuracy of UAV multispectral remote sensing inversion of salinity based on back ...propagation neural network (BPNN) is low, in this study, used the UAV multispectral image and field measurements of 60 soil surface salinity as data sources, 16 salinity indexs were constructed using the extracted spectral reflectance, and performed a gray relation analysis to screen salinity index features after applying a film removal to construct the BPNN salinity inversion model. Particle swarm optimization (PSO), thinking evolutionary algorithm (MEA), and genetic algorithm (GA) were applied to optimize the BPNN inverse model, respectively, and the optimization capabilities of the four algorithms were compared and evaluated to optimize the best optimization algorithm. The results showed that the GRA variable screening can effectively remove the redundant information of spectral parameters and reduce the complexity of the salinity inversion model; the PSO, MEA, and GA can effectively improve the robusticity of BPNN inversion model, and GA algorithm has the best optimization effect in terms of inverse model optimization effect, followed by MEA and PSO algorithms; the accuracy of the PSO-BPNN, MEA-BPNN, and GA-BPNN inversion models are better than that of the BPNN model, and GA-BPNN is the best salinity inversion model, which achieves R 2 of 0.6659, RMSE of 0.0751, and RPD of 2.0211. This approach can effectively solve salinity monitoring accuracy issues of UAV multispectral inversion.
To our knowledge, no structural study to date has characterized, in an intact receptor, the coupling of conformational change in extracellular domains through a single-pass transmembrane domain to ...conformational change in cytoplasmic domains. Here we examine such coupling, and its unexpected complexity, using nearly full-length epidermal growth factor receptor (EGFR) and negative-stain EM. The liganded, dimeric EGFR ectodomain can couple both to putatively active, asymmetrically associated kinase dimers and to putatively inactive, symmetrically associated kinase dimers and monomers. Inhibitors that stabilize the active or inactive conformation of the kinase active site, as well as mutations in the kinase dimer interface and a juxtamembrane phosphorylation site, shift the equilibrium among the three kinase association states. This coupling of one conformation of an activated receptor ectodomain to multiple kinase-domain arrangements reveals previously unanticipated complexity in transmembrane signaling and facilitates regulation of receptor function in the juxtamembrane and cytoplasmic environments.
Abstract
The spatiotemporal variation of the model parameters of the soil-water characteristic curve (SWCC) reflect the soil water holding capacity and soil pore distribution state. It is an integral ...part of interdisciplinary disciplines such as soil hydrodynamics and ecohydrology. The authors selected the optimal SWCC model for the Lanzhou collapsible loess, used classical statistics and geostatistics methods to study the spatiotemporal variability of the SWCC model parameters, and using the comprehensive comparison of the mean relative differences (MRD), standard deviations (SDRD) and an index of temporal stability (ITS) determined the representativeness measuring point. The results showed that the SWCC parameter α was medium variability in the 0–30 cm soil layer, n and θs were of low variability, and the spatial distribution of the parameters of different soil layers was consistent. Migration direction prediction of θs was very similar in each layer, α, n and θs were all strongly significantly correlated positively. Moreover, the determination coefficient of representative measuring point 16 had the highest prediction accuracy for the measured values of SWCC. The results of this paper can be used as a simple method to predict SWCC and provide theoretical guidance for soil water management and soil collapse erosion monitoring in the collapsible loess area.
The tubular structure of the endoplasmic reticulum (ER) appears to be generated by integral membrane proteins, the reticulons and a protein family consisting of DP1 in mammals and Yop1p in yeast. ...Here, individual members of these families were found to be sufficient to generate membrane tubules. When we purified yeast Yop1p and incorporated it into proteoliposomes, narrow tubules (~15 to 17 nanometers in diameter) were generated. Tubule formation occurred with different lipids; required essentially only the central portion of the protein, including its two long hydrophobic segments; and was prevented by mutations that affected tubule formation in vivo. Tubules were also formed by reconstituted purified yeast Rtn1p. Tubules made in vitro were narrower than normal ER tubules, due to a higher concentration of tubule-inducing proteins. The shape and oligomerization of the "morphogenic" proteins could explain the formation of the tubular ER.
Abstract
Quorum sensing (QS) is a crucial regulatory mechanism controlling bacterial signalling and holds promise for novel therapies against antimicrobial resistance. In Gram-positive bacteria, such ...as
Streptococcus pneumoniae
, ComA is a conserved efflux pump responsible for the maturation and secretion of peptide signals, including the competence-stimulating peptide (CSP), yet its structure and function remain unclear. Here, we functionally characterize ComA as an ABC transporter with high ATP affinity and determined its cryo-EM structures in the presence or absence of CSP or nucleotides. Our findings reveal a network of strong electrostatic interactions unique to ComA at the intracellular gate, a putative binding pocket for two CSP molecules, and negatively charged residues facilitating CSP translocation. Mutations of these residues affect ComA’s peptidase activity in-vitro and prevent CSP export in-vivo. We demonstrate that ATP-Mg
2+
triggers the outward-facing conformation of ComA for CSP release, rather than ATP alone. Our study provides molecular insights into the QS signal peptide secretion, highlighting potential targets for QS-targeting drugs.
Negative stain electron microscopy (EM) and adhesion assays show that α X β 2 integrin activation requires headpiece opening as well as extension. An extension-inducing Fab to the β 2 leg, in ...combination with representative activating and inhibitory Fabs, were examined for effect on the equilibrium between the open and closed headpiece conformations. The two activating Fabs stabilized the open headpiece conformation. Conversely, two different inhibitory Fabs stabilized the closed headpiece conformation. Adhesion assays revealed that α X β 2 in the extended-open headpiece conformation had high affinity for ligand, whereas both the bent conformation and the extended-closed headpiece conformation represented the low affinity state. Intermediate integrin affinity appears to result not from a single conformational state, but from a mixture of equilibrating conformational states.
We report the near atomic resolution (3.3 Å) of the human polycystic kidney disease 2-like 1 (polycystin 2-l1) ion channel. Encoded by PKD2L1, polycystin 2-l1 is a calcium and monovalent ...cation-permeant ion channel in primary cilia and plasma membranes. The related primary cilium-specific polycystin-2 protein, encoded by PKD2, shares a high degree of sequence similarity, yet has distinct permeability characteristics. Here we show that these differences are reflected in the architecture of polycystin 2-l1.
Ribonucleotide reductase (RR) is an α(n)β(n) (RR1-RR2) complex that maintains balanced dNTP pools by reducing NDPs to dNDPs. RR1 is the catalytic subunit, and RR2 houses the free radical required for ...catalysis. RR is allosterically regulated by its activator ATP and its inhibitor dATP, which regulate RR activity by inducing oligomerization of RR1. Here, we report the first X-ray structures of human RR1 bound to TTP alone, dATP alone, TTP-GDP, TTP-ATP, and TTP-dATP. These structures provide insights into regulation of RR by ATP or dATP. At physiological dATP concentrations, RR1 forms inactive hexamers. We determined the first X-ray structure of the RR1-dATP hexamer and used single-particle electron microscopy to visualize the α(6)-ββ'-dATP holocomplex. Site-directed mutagenesis and functional assays confirm that hexamerization is a prerequisite for inhibition by dATP. Our data indicate a mechanism for regulating RR activity by dATP-induced oligomerization.
Abstract
Gravel mulching is an ancient mulching system with a history of more than 300 years in China. To explore the changes of soil-water content (SWC) and heat transport in watermelon ...gravel-mulched fields under drip irrigation, we simulated three irrigation quotas (W1, 180 m3/hm2; W2, 270 m3/hm2; and W3, 360 m3/hm2) and three irrigation frequencies (F1, three times; F2, six times; and F3, nine times) based on HYDRUS-2D. The results indicated that peak SWC increased with irrigation quota. The range of fluctuation of SWC decreased as irrigation frequency increased. The temperature of the 0–40 cm soil layer varied with air temperature, but the range of fluctuation decreased with depth. Irrigation affected the distribution of soil water, increased soil heat capacity, and reduced the impact of air temperature on soil temperature, thus delaying the impact of air temperature on soil temperature. High-frequency drip irrigation could therefore effectively improve SWC, reduce water stress during the period of watermelon growth, and effectively delay the effect of air temperature on soil temperature, providing a theoretical basis for developing reasonable irrigation strategies and regulating soil water and heat in gravel-mulched fields.
Based on the self-developed high permeability water pressure loading system, the physical and mechanical properties and pore structure evolution under various high permeability water pressures were ...studied. This study aims to reveal the microscopic damage mechanism of concrete when subjected to high permeability water pressures. The results indicate that the internal water content increases with the rising of water pressure under various high permeability conditions. Furthermore, the higher the water pressure, the greater the reduction in strength, particularly evident in low-strength-grade concrete. High permeability water pressure causes to the expansion of gelatinized pores with small sizes into transition pores. Moreover, there is a concurrent alteration in both pore size and pore number under high permeability water pressure.
•The high permeability water pressure loading was simulated by self-designed equipment.•The concrete strength damage and water content change under high permeability water pressure was tested.•The damage mechanism was revealed through the change of pore structure.
PDF
