Uncover Single Nanoparticle Dynamics on Live Cell Membrane with Data-Driven Historical Experience Analysis.

Understanding the spatiotemporal dynamics of particles in a complex biological environment is crucial for the study of related biological processes. To analyze the complicated trajectories recorded from single-particle tracking (SPT), we have proposed a method named SEES based on historical experience vector analysis, which allows both the global patterns and local state continuities of a trajectory to emerge by themselves as color segments without predefined models. This method implements a data-driven strategy and thus uncovers the hidden information with less prior knowledge or subjective bias. Here, we demonstrate its efficiency by comparing its performance with the Hidden Markov model (HMM), one of the most widely used methods in time series processing. The results demonstrated that the SEES operator was more sensitive in identifying rare events and could utilize multivariable observations in the dynamic processes to uncover more details. We applied the method to analyze the dynamics of nanoparticles interacting with live cells expressing programmed death ligand 1 (PD-L1) on the membrane. The results showed that the SEES operator can successfully pinpoint the transmembrane rare events, visualize the on-membrane "Brownian searching" motion, and evaluate different dynamics among multiple trajectories. Furthermore, we found that the PD-L1 expression level on the cell membrane affected the rotation behavior of the nanoparticle as well as the cellular uptake efficiency. These findings enabled by SEES could potentially help the rational design of highly efficient nanocargoes.

Plant adaptability in karst regions.

Karst ecosystems are formed by dissolution of soluble rocks, usually with conspicuous landscape features, such as sharp peaks, steep slopes and deep valleys. The plants in karst regions develop special adaptability. Here, we reviewed the research progresses on plant adaptability in karst regions, including drought, high temperature and light, high-calcium stresses responses and the strategies of water utilization for plants, soil nutrients impact, human interference and geographical traits on karst plants. Drought, high temperature and light change their physiological and morphological structures to adapt to karst environments. High-calcium and soil nutrients can transfer surplus nutrients to special parts of plants to avoid damage of high nutrient concentration. Therefore, karst plants can make better use of limited water. Human interference also affects geographical distribution of karst plants and their growing environment. All of these aspects may be analyzed to provide guidance and suggestions for related research on plant adaptability mechanisms.

Sequence-Modulated Interactions between Single Multivalent DNA-Conjugated Gold Nanoparticles.

DNA-conjugated gold nanoparticle (AuNP) is an attractive building block to construct elegant plasmonic nanomaterials by self-assembly but the complicated interaction between multivalent nanoconjugates governing the assembly process and the properties of assembled structures remains poorly understood. Herein, with an in situ kinetic single-particle imaging method, we report the dynamic interaction between single multivalent DNA-conjugated AuNPs quantitatively depends on the nucleic acid sequence in nanoconjugates. From the binding dynamics analysis, it was found that the binding of nanoconjugates with DNA length longer than nine bases is kinetically irreversible and the binding rate is dependent on both the sequence length and GC content, enabling us to predict the rational modulation of binding rates of individual building blocks for stepwise assembly. Moreover, the reversibility for the multivalent interaction between single nanoconjugates at constant temperature can be reinstated by adopting the DNA sequence with single-nucleotide mismatch and the lifetime for nanoconjugates at bound state can be tailored by changing the mismatch positions in DNA strands, providing new opportunity to create active nanostructures with controlled dynamic properties. All these findings provide new insights for understanding the multivalent interaction during the assembly process at the single-nanoconjugate level and predicting the programmable self-assembly of engineered nanoconjugates for the fabrication of dynamic nanomaterials.

Plasmon resonances in a stacked pair of graphene ribbon arrays with a lateral displacement.

We find that a stacked pair of graphene ribbon arrays with a lateral displacement can excite plasmon waveguide mode in the gap between ribbons, as well as surface plasmon mode on graphene ribbon surface. When the resonance wavelengthes of plasmon waveguide mode and surface plasmon mode are close to each other, there is a strong electromagnetic interaction between the two modes, and then they contribute together to transmission dip. The plasmon waveguide mode resonance can be manipulated by the lateral displacement and longitudinal interval between arrays due to their influence on the manner and strength of electromagnetic coupling between two arrays. The findings expand our understanding of electromagnetic resonances in graphene-ribbon array structure and may affect further engineering of nanoplasmonic devices and metamaterials.

Effect of Lankford Coefficients on Springback Behavior during Deep Drawing of Stainless Steel Cylinders.

Accurate prediction of springback is increasingly required during deep-drawing formation of anisotropic stainless steel sheets. The anisotropy of sheet thickness direction is very important for predicting the springback and final shape of a workpiece. The effect of Lankford coefficients (r00, r45, r90) with different angles on springback was investigated using numerical simulation and experiments. The results show that the Lankford coefficients with different angles each have a different influence on springback. The diameter of the straight wall of the cylinder along the 45-degree direction decreased after springback, and showed a concave valley shape. The Lankford coefficient r90 had the greatest effect on the bottom ground springback, followed by r45 and then r00. A correlation was established between the springback of workpiece and Lankford coefficients. The experimental springback values were obtained by using a coordinate-measuring machine and showed good agreement with the numerical simulation results.

Tranilast attenuates lipopolysaccharide­induced lung injury via the CXCR4/JAK2/STAT3 signaling pathway.

It has been reported that the expression of C­X­C motif chemokine receptor 4 (CXCR4) is increased in patients with lung injury, while CXCR4 downregulation can improve sepsis­induced lung injury. Previous studies have shown that tranilast can inhibit CXCR4 mRNA expression. Therefore, the present study aimed to investigate whether tranilast could protect against lipopolysaccharide (LPS)­induced lung injury via the CXCR4/Janus kinase 2 (JAK2)/STAT3 signaling pathway. A Cell Counting Kit­8 assay was performed to evaluate the effect of different concentrations of tranilast on the viability of LPS­induced BEAS­2B cells. The mRNA and protein expression levels of the inflammatory factors, TNFα, IL­1ß, IL­6, cytochrome c oxidase subunit II and inducible nitric oxide synthase were detected using reverse transcription­quantitative PCR and western blot analysis, respectively. In addition, the cell apoptosis rate and the expression levels of apoptosis­related proteins were analyzed using a TUNEL staining assay and western blot analysis, respectively. The expression levels of the CXCR4/JAK2/STAT3 signaling pathway­related proteins were also determined using western blot analysis. Furthermore, the effects of tranilast on cell viability, inflammation and apoptosis were also evaluated in LPS­stimulated BEAS­2B cells following CXCR4 overexpression, which were pre­treated with tranilast. The results demonstrated that tranilast could alleviate LPS­induced cell viability, the secretion of inflammatory cytokines and cell apoptosis. In addition, cell treatment with tranilast inhibited the expression of CXCR4/JAK2/STAT3 signaling­related proteins in LPS­induced BEAS­2B cells. Following CXCR4 overexpression, the alleviating effect of tranilast on cell viability, inflammatory response and apoptosis was notably attenuated. Overall, the current study suggested that tranilast could attenuate LPS­induced lung injury via the CXCR4/JAK2/STAT3 signaling pathway, suggesting that tranilast could be considered as a promising agent for treating sepsis­induced acute lung injury.

microRNA-15a-5p participates in sepsis by regulating the inflammatory response of macrophages and targeting TNIP2.

The mortality rate for patients experiencing sepsis is decreasing; however, an effective therapeutic strategy requires further investigation. Increasing evidence has supported the idea that dysregulated microRNAs (miR) participate in the development of sepsis. Meanwhile, macrophages are crucial players in various inflammatory responses and diseases. The objective of the current study was to investigate the associated molecular mechanisms of action of miR-15a-5p on inflammatory responses in lipopolysaccharide (LPS)-stimulated mouse macrophages and the macrophage cell line RAW264.7. RAW264.7 macrophages were stimulated with LPS for 4 h, and ELISAs were subsequently used to measure the expression levels of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-α, interleukin (IL)-1ß and IL-6, in RAW264.7 macrophages. The expression levels of miR-15a-5p in RAW264.7 macrophages were detected after the stimulation of LPS using reverse transcription quantitative-PCR. The results indicated that the IL-1ß, IL-6, TNF-α and miR-15a-5p levels were significantly increased compared with the control group. The Target gene prediction database (TargetScan) and dual-luciferase reporter assays were subsequently employed, and TNF-α induced protein 3-interacting protein 2 (TNIP2) was confirmed as a direct target for miR-15a-5p. Additionally, it was found that the TNIP2 expression levels were decreased in RAW264.7 macrophages following LPS treatment compared with controls. The present study also examined the effects of miR-15a-5p inhibitor on inflammatory cytokine expression levels and the activation of the NF-κ signaling pathway. These results demonstrated that miR-15a-5p inhibitor reduced the secretion of inflammatory cytokines and inhibited NF-κ pathway activation by targeting TNIP2. This may be associated with the progression of sepsis. Meanwhile, a LPS-induced mouse model of sepsis was established to examine the regulation of TNIP2 and miR-15a-5p during inflammation. In the animal model, miR-15a-5p inhibitor significantly suppressed the secretion of inflammatory factors. The levels of creatin, blood urea nitrogen, aspartate aminotransferase and alanine aminotransferase in the serum of LPS-treated mice were also found to be decreased in the miR-15a-5p inhibitor treatment group, while the protective effects of miR-15a-5p inhibitor on sepsis were eliminated by TNIP2-small interfering RNA combination therapy. In conclusion, the present findings indicated that miR-15a-5p may be involved in the inflammatory process during sepsis by activating the NF-κ pathway and targeting TNIP2. This suggests that miR-15a-5p inhibitor may be a novel anti-inflammatory agent and therapeutic strategy for sepsis.

Are vegetated drainage ditches effective for nitrogen removal under cold temperatures?

Vegetated ditches are widely used to treat agricultural wastewater, but effective nitrogen removal at low temperatures remains a challenge because plants wilt in the winter. In this study, three simulated drainage ditches vegetated with Myriophyllum aquaticum were operated with low, medium, and high water levels to study ammonium nitrogen (NH4+-N) removal under cold temperatures. The M. aquaticum ditches had a mean NH4+-N removal efficiency of 75.8-86.8% throughout cold period. Based on nitrogen mass balance, plant uptake, sediment adsorption, and microbial removal accounted for 12.4-21.5%, 0.0-8.1%, and 38.9-54.6% of the influent total nitrogen loading, respectively. The accumulation of nitrate confirmed that intense microbial nitrification occurred in M. aquaticum ditches even at low temperature. These results suggest that M. aquaticum is appropriate as a cold-tolerant plant for NH4+-N removal in drainage ditches.

Tracking variation of fluorescent dissolved organic matter during full-scale printing and dyeing wastewater treatment.

In this study, fluorescent dissolved organic matter (FDOM) in real printing and dyeing wastewater (PDW) during full-scale two-stage treatment was characterized using excitation-emission matrix (EEM), apparent molecular weight (AMW) cutoff by centrifugal ultrafiltration and high-performance liquid chromatography with fluorescence detector (HPLC-FLD). EEMs of PDW during treatment were relatively invariable with two typical and dominant peaks (P1, 275/320 nm and P2, 230/340 nm). The removal rates of P1 intensity and P2 intensity were both lower than those of DOC or UVA254 during the 1st stage and 2nd stage treatment. The <3 kDa fraction made major contribution to DOC, UVA254, P1 and P2 intensity. The DOM fractions with different AMW exhibited different removal behaviors during the 1st stage and 2nd stage treatment. The <3 kDa fraction of FDOM was poorly removed by biological treatment alone. The HPLC-FLD multi-emission scan results indicated that the major part of FDOM clusters were hydrophilic and they were more difficult to remove than the transphilic and hydrophobic FDOM clusters. According to the physicochemical properties of FDOM in PDW, selective adsorption and advanced oxidation process could be prior options for PDW advanced treatment.

Stimulation of optimized influent C:N ratios on nitrogen removal in surface flow constructed wetlands: Performance and microbial mechanisms.

Exploring optimal C:N ratio is necessary to ensure balanced microbial nitrification and denitrification in constructed wetlands (CWs), which has become an important management practice for more efficient nitrogen removal and sustainability of CWs. Surface flow constructed wetlands (SFCWs) vegetated with Myriophyllum aquaticum were designed to investigate the effects of five different influent C:N ratios (0:1, 2.5:1, 5:1, 10:1, and 15:1) on nitrogen removal performance and microbial communities over a 175-day experimental period. Compared to the influent C:N ratios of 0:1, higher NH4+-N, NO3--N, and total nitrogen (TN) removal efficiencies and lower NO3--N accumulation were observed at influent C:N ratios higher than 5:1. In addition, the highest TN removal efficiency (70.4%) and the lowest nitrous oxide emission flux (4.12 mg m-2 d-1) were obtained at the influent C:N ratio of 5:1. High-throughput sequencing revealed that influent C:N ratios altered the distribution and composition of microbial communities in the sediment, which resulted in a dynamic interplay between N-transforming functional microbes and NH4+-N and NO3--N removal. In particular, the dominant denitrifiers, including Desulfovibrio, Zoogloea, and Dechloromonas, were more abundant in the sediment with an influent C:N ratio of 5:1, which contributed to the high N removal rate. These findings may be used to screen for an optimum influent C:N ratio to maintain the sustainability of SFCWs with higher N removal efficiency.

Local and regional drivers of turnover and nestedness components of species and functional beta diversity in lake macrophyte communities in China.

Beta diversity describes the variation in species composition between sites and is often influenced by both local and regional processes. Partitioning beta diversity into turnover (species replacement between sites) and nestedness (richness difference between sites) components may enhance our understanding of the mechanisms behind the local and regional drivers determining species composition across spatial scales. We sampled macrophyte communities in 24 lakes in two regions (Yangtze River basin and Yunnan-Guizhou plateau) of China covering broad climate and nutrient gradients. Based on both species and functional approaches, we calculated multiple-site beta diversity using the Sørensen dissimilarity index and partitioned it into turnover and nestedness coefficients crossed with two nested spatial scales: among depths within transects (transect scale) and among transects within lakes (lake scale). The overall species beta diversity and functional beta diversity (i.e. Sørensen coefficient) were significantly lower and thus more homogeneous at lake scale. Across spatial scales, species beta diversity was mainly explained by turnover patterns (56-61%) and functional beta diversity primarily by nestedness patterns (58-65%). Both local and regional drivers contributed to structuring species and functional beta diversity patterns, largely through changes in species turnover and functional nestedness, respectively. Overall, we observed a significant increase in species beta diversity and its turnover component while a decreasing trend in functional beta diversity and its nestedness component at high altitude. Our results further emphasized that the species beta diversity and its turnover component decreased at high total phosphorus concentration (TP) across the two spatial scales, while the functional beta diversity and its nestedness component decreased at high TP at the transect scale. We conclude that understanding of the relative role of local and regional drivers in determining macrophyte diversity patterns may help managers to select the most appropriate conservation strategies for preservation of biodiversity varying with the scale in focus.

Single Plasmonic Nanosprings for Visualizing Reactive-Oxygen-Species-Activated Localized Mechanical Force Transduction in Live Cells.

Mechanical force signaling in cells has been regarded as the biological foundation of various important physiological functions. To understand the nature of these biological and physiological processes, imaging and determining the mechanical signal transduction dynamics in live cells are required. Herein, we proposed a strategy to determine mechanical force as well as its changes with single-particle dark-field spectral microscopy by using a single plasmonic nanospring as a mechanical sensor, which can transfer force-induced molecular extension/compression into spectral responses. With this robust plasmonic nanospring, we achieved the visualization of activation of localized mechanical force transduction in single live cells triggered by reactive-oxygen-species (ROS) stimulation. The successful demonstration of a biochemical ROS signal to mechanical signal conversion suggested this strategy is promising for studying mechanical force signaling and regulation in live biological systems.