Predicting carbon storage of mixed broadleaf forests based on the finite mixture model incorporating stand factors,site quality,and aridity index

The diameter distribution function(DDF)is a crucial tool for accurately predicting stand carbon storage(CS).The current key issue,however,is how to construct a high-precision DDF based on stand factors,site quality,and aridity index to predict stand CS in multi-species mixed forests with complex structures.This study used data from70 survey plots for mixed broadleaf Populus davidiana and Betula platyphylla forests in the Mulan Rangeland State Forest,Hebei Province,China,to construct the DDF based on maximum likelihood estimation and finite mixture model(FMM).Ordinary least squares(OLS),linear seemingly unrelated regression(LSUR),and back propagation neural network(BPNN)were used to investigate the influences of stand factors,site quality,and aridity index on the shape and scale parameters of DDF and predicted stand CS of mixed broadleaf forests.The results showed that FMM accurately described the stand-level diameter distribution of the mixed P.davidiana and B.platyphylla forests;whereas the Weibull function constructed by MLE was more accurate in describing species-level diameter distribution.The combined variable of quadratic mean diameter(Dq),stand basal area(BA),and site quality improved the accuracy of the shape parameter models of FMM;the combined variable of Dq,BA,and De Martonne aridity index improved the accuracy of the scale parameter models.Compared to OLS and LSUR,the BPNN had higher accuracy in the re-parameterization process of FMM.OLS,LSUR,and BPNN overestimated the CS of P.davidiana but underestimated the CS of B.platyphylla in the large diameter classes(DBH≥18 cm).BPNN accurately estimated stand-and species-level CS,but it was more suitable for estimating stand-level CS compared to species-level CS,thereby providing a scientific basis for the optimization of stand structure and assessment of carbon sequestration capacity in mixed broadleaf forests.

Role of hydrogen peroxide in stress-induced programmed cell death during somatic embryogenesis in Fraxinus mandshurica

We examined how reactive oxygen species, in the form of hydrogen peroxide (H2O2), affect osmotic stress–induced programmed cell death during somatic embryogenesis from cotyledon explants of Manchurian ash (Fraxinus mandshurica Rupr.). We found that substantial osmotic stress was essential for Manchurian ash somatic cells to obtain embryogenic competence. The explant cells displayed hallmarks of programmed cell death, chromatin condensation, and DNA fragmentation to oligonucleotides during somatic embryogenesis. Increasing concentrations of plant growth regulators and sucrose in the medium increased osmotic stress thereby inducing H2O2 accumulation in the explant cells. We found that H2O2 concentration was significantly decreased in explant cells when the induction medium was modified, i.e., when reducing the concentration of sucrose, which reduces the osmotic pressure of the medium, or by withdrawing plant growth regulators at mid-culture. These treatments also decreased the proportion of explant cells undergoing programmed cell death. Accordingly, a decreased rate of somatic embryo induction was observed. These results show that PCD occurred during tissue browning and death of some explant cells during somatic embryogenesis in F. mandshurica. The ROS contributed to PCD in abiotic stress stimulated F. mandshurica cells.

Effects of environmental factors on seedling growth and anthocyanin content in Betula ‘Royal Frost’ leaves

Determining the influences of environmental factors on seedling growth and leaf color may improve our understanding of the chromogenic mechanisms in leaves and the biosynthesis of anthocyanin. To determine the optimum conditions for Betula 'Royal Frost' seedling cultivation, we assessed seedling growth and anthocyanin content under natural conditions. The temperature had a significant influence on height but not on radial growth. Between June and September, the anthocyanin content was significantly positively correlated with light intensity and air moisture and significantly negatively correlated with temperature. In single-factor experiments to determine the variation in anthocyanin content in the greenhouse, anthocyanin content increased with increasing soil water content and at first increased, then decreased with increasing pH of the irrigation water and temperature, but decreased with increasing light intensity. K2SO4 can increase the anthocyanin content. So to maintain leaf color, seedlings should be cultivated with < 200 mu mol m(-2) s(-1) light intensity at 20 A degrees C and soil moisture content between 60 and 90%, and the irrigation water should be neutral or alkaline. Additionally, spraying with K2SO4 can be beneficial.

Effects of a nitric oxide donor and nitric oxide scavengers on Sorbus pohuashanensis embryo germination

The effects of an exogenous nitric oxide donor(sodium nitroprusside, SNP), a NO scavenger 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxode(PTIO) and carboxy-PTIO potassium salt(c PTIO) on the embryo germination of Sorbus pohuashanensis were studied in a petri dish test. SNP at 0.5–5 mmol L-1 increased germination percentage, mean time to germination, germination index and germination energy compared with the control to different degrees. Treatment with 2 mmol L-1 SNP improved germination most significantly; embryo germination percentage for mother tree 1(91.11%) and mother tree 2(64.44%) were much higher than the control. In addition,excessive SNP levels did not enhance embryo germination.Combined treatment with SNP and an NO scavenger delayed embryo germination. Treatment with c PTIO inhibited embryo germination; germination percentage was 42.22% and was lower than that of the control. These results show that low concentrations of exogenous NO can enhance the embryo germination of S. pohuashanensis,providing a simple, effective way for promoting germination of S. pohuashanensis.

Reactive oxygen species, nitric oxide and plant cell death associated with caspase-like protease activity during somatic embryogenesis in Fraxinus mandshurica

Programmed cell death occurs in browning explants of Fraxinus mandshurica during somatic embryogenesis, but the underlying mechanism is unclear. In this study, single cotyledons of zygotic embryos of F. mandshurica were used as explants. Mitochondrial structure and function, caspase-3-like protease activity, hydrogen peroxide metabolism, and nitric oxide accumulation induced by high concentrations of sucrose and plant growth regulators were studied. The results show that plant growth regulators induced somatic embryogenesis and also promoted explant browning. High sucrose concentrations had similar effects. High concentrations of sucrose and plant growth regulators led to the accumulation of hydrogen peroxide and nitric oxide which induced changes in mitochondrial structure and function such as modifications in mitochondrial morphology, increased membrane permeability, decreased membrane potential, and the release of cytochrome c into the cytoplasm. An increase in caspase-3-like protease activity triggered programmed cell death in some browning explant cells. During somatic embryogenesis there were increased activities of superoxide dismutase, peroxidase, and catalase, which are associated with hydrogen peroxide metabolism and jointly maintain reactive oxygen species levels. Intracellular nitric oxide synthase and nitrate reductase activities were not significantly correlated with nitric oxide content. Instead, intracellular nitric oxide may be derived from non-enzymatic reactions. Our results indicate that hydrogen peroxide and nitric oxide may function as signals, playing key roles in somatic embryogenesis and programmed cell death of explant cells of F. mandshurica. The interaction between nitric oxide and reactive oxygen species determines the occurrence of programmed cell death in explant cells;somatic embryogenesis and programmed cell death are positively regulated by hydrogen peroxide. However, the regulation of nitric oxide is complex.

Relationship between H_(2)O_(2) accumulation and NO synthesis during osmotic stress:promoted somatic embryogenesis of Fraxinus mandshurica

Osmotic stress promotes somatic embryogenesis of Fraxinus mandshurica,which leads to accumulation of reactive oxygen species(ROS).The single pieces of cotyledons of F.mandshurica were used as explants to induce somatic embryogenesis in osmotic-stress medium.Furthermore,the hydrogen peroxide H_(2)O_(2) content of explanted cells was varied by adding exogenous H_(2)O_(2) or catalase solution to assess the effects of the exogenous H_(2)O_(2)on somatic embryogenesis,intracellular H_(2)O_(2)accumulation,and the relationship between signaling mediated by ROS or reactive nitrogen species.The results revealed that exogenous H_(2)O_(2)(100?300μmol L^(–1))increased the number of somatic embryos.On 60th day of exogenous H_(2)O_(2)(200μmol L^(–1))treatment,the number of somatic embryos of explants treated,which was 136.54%,was higher than the control.Moreover,exogenous H_(2)O_(2)(100μmol L^(–1))significantly increased the intracellular H_(2)O_(2)content and enhanced the activities of superoxidase dismutase and peroxidase.Finally,exogenous H_(2)O_(2)(100μmol L^(–1))activated the intracellular non-enzymatic pathway for nitric oxide(NO)synthesis.The somatic embryogenesis in broadleaf trees increases with the change of endogenic ROS content,and depends on the upregulation of antioxidant enzymes.Both H_(2)O_(2)and NO,as signaling molecules,were found to be involved in the process of somatic embryogenesis in broadleaf trees.In the process of exogenous H_(2)O_(2)promoting somatic embryogenesis,NO synthesis depended on non-enzymatic reactions.These results provide a scientific basis for resolving the mechanism by which ROS levels are regulated during somatic embryogenesis of broadleaf trees and establish a reasonable and efficient technology system for regulating somatic embryogenesis of trees.

Correction to:Reactive oxygen species,nitric oxide and plant cell death associated with caspase-like protease activity during somatic embryogenesis in Fraxinus mandshurica

Correction to:J.For.Res.https://doi.org/10.1007/s11676-021-01392-y In this article Ling Yang should have been denoted as a corresponding author.The original article has been corrected.Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affi liations.

Ancient dormant virus remnant ERVW-1 drives ferroptosis via degradation of GPX4 and SLC3A2 in schizophrenia

Human endogenous retroviruses(HERVs)are remnants of retroviral infections in human germline cells from millions of years ago.Among these,ERVW-1(also known as HERV-W-ENV,ERVWE1,or ENVW)encodes the envelope protein of the HERV-W family,which contributes to the pathophysiology of schizophrenia.Additionally,neuropathological studies have revealed cell death and disruption of iron homeostasis in the brains of individuals with schizophrenia.Here,our bioinformatics analysis showed that differentially expressed genes in the human prefrontal cortex RNA microarray dataset(GSE53987)were mainly related to ferroptosis and its associated pathways.Clinical data demonstrated significantly lower expression levels of ferroptosis-related genes,particularly Glutathione peroxidase 4(GPX4)and solute carrier family 3 member 2(SLC3A2),in schizophrenia patients compared to normal controls.Further in-depth analyses revealed a significant negative correlation between ERVW-1 expression and the levels of GPX4/SLC3A2 in schizophrenia.Studies indicated that ERVW-1 increased iron levels,malondialdehyde(MDA),and transferrin receptor protein 1(TFR1)expression while decreasing glutathione(GSH)levels and triggering the loss of mitochondrial membrane potential,suggesting that ERVW-1 can induce ferroptosis.Ongoing research has shown that ERVW-1 reduced the expression of GPX4 and SLC3A2 by inhibiting their promoter activities.Moreover,Ferrostatin-1(Fer-1),the ferroptosis inhibitor,reversed the iron accumulation and mitochondrial membrane potential loss,as well as restored the expressions of ferroptosis markers GSH,MDA,and TFR1 induced by ERVW-1.In conclusion,ERVW-1 could promote ferroptosis by downregulating the expression of GPX4 and SLC3A2,revealing a novel mechanism by which ERVW-1 contributes to neuronal cell death in schizophrenia.

Optimizing piezoelectric performance of complex perovskite through increasing diversity of B-site cations

Piezoelectric materials with unique properties are hugely appealing for high sensitivity sensors and ultrasonic transducers.Here,Pb(Ni_(1/3)Nb_(2/3))O_(3)-Pb(Yb_(1/2)Nb_(1/2))O_(3)-PbTiO_(3)piezoelectric system was designed and investigated in detail.The optimized piezoelectric response(d_(33)=826 pC/N,d_(33)∗=1017 pm/V)together with good temperature stability and negligible performance degradation up to 10^(6) cycles was achieved in 0.58PNN-0.10PYN-0.32PT composition.Rayleigh analysis revealed the amplification of intrinsic and extrinsic contributions in MPB region due to more spontaneous polarization orientations and an increase in chemical disorder of system after the introduction of PYN.The origin of high piezoelectric response was investigated through the combination of scanning electron microscopy and piezoresponse force microscopy.The diversity of B-site cations was shown to enhance local structural heterogeneity,weaken long-range ferroelectric ordered domains,and lower free energy barrier via the formation of nanodomain configuration that promoted polarization rotation,thereby improving piezoelectric properties of the material.Therefore,it is suggested that increasing the diversity of B-site cations is an effective strategy for achieving outstanding piezoelectric performance.

A Comparison Study of Sinterability and Electrical Properties for Microwave and Conventional Sintered Mn_(0.43)Ni_(0.9)CuFe_(0.67)O_4 Ceramics

In this paper, a quaternary system of Mn0.43Ni0.9CuFe0.67O4 negative temperature coefficient （NTC） thermistor ceramic prepared by solid/solid reaction was sintered by microwave and conventional method, respectively. To characterize the sinterability of the samples, the densification parameter, porosity and grain size distribution of the bulk were determined. The crystal structure, phase compositions, morphology and impedance of the samples were analyzed by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, energy-dispersive spectroscopy （EDS） and impedance analysis. The experimental results confirmed that the sinterability and electrical properties of ceramics were homogenously improved by microwave sintering.

Identification and mapping of soybean and maize crops based on Sentinel-2 data

Soybean and maize are important raw materials for the production of food and livestock feed.Accurate mapping of these two crops is of great significance to crop management,yield estimation,and crop-damage control.In this study,two towns in Guoyang County,Anhui Province,China,were selected as the study area,and Sentinel-2 images were adopted to map the distributions of both crops in the 2019 growing season.The data obtained on August 18(early pod-setting stage of soybean)was determined to be the most applicable to soybean and maize mapping by means of the Jeffries-Matusita(JM)distance.Subsequently,three machine-learning algorithms,i.e.,random forest(RF),support vector machine(SVM)and back-propagation neural network(BPNN)were employed and their respective performance in crop identification was evaluated with the aid of 254 ground truth plots.It appeared that RF with a Kappa of 0.83 was superior to the other two methods.Furthermore,twenty candidate features containing the reflectance of ten spectral bands(spatial resolution at 10 m or 20 m)and ten remote-sensing indices were input into the RF algorithm to conduct an important assessment.Seven features were screened out and served as the optimum subset,the mapping results of which were assessed based on the ground truth derived from the unmanned aerial vehicle(UAV)images covering six ground samples.The optimum feature-subset achieved high-accuracy crop mapping,with a reduction of data volume by 65%compared with the total twenty features,which also overrode the performance of ten spectral bands.Therefore,feature-optimization had great potential in the identification of the two crops.Generally,the findings of this study can provide a valuable reference for mapping soybean and maize in areas with a fragmented landscape of farmland and complex planting structure.

Fast extraction of winter wheat planting area in Huang-Huai-Hai Plain using high-resolution satellite imagery on a cloud computing platform

To extract regional winter wheat planting area using higher-resolution satellite imagery still faces many challenges due to large data size and long processing time in traditional remote sensing classification.Google Earth Engine(GEE),a cloud computing analysis platform based on global geospatial analysis,provides a new opportunity for rapid analysis of remote sensing data.In this study,high-quality Landsat-8 imagery was used to extract the winter wheat planting area from the Huang-Huai-Hai Plain in China.The random forest algorithm was used to identify and map the winter wheat sown in 2019 and harvested in 2020,and Sentinel-2 imagery was used to verify the results.The spectral indices,texture,and terrain features of the image were derived,and their contribution to the classification accuracy of winter wheat was evaluated by scoring.Then the top nine features were selected to form an optimal feature subset.Comparing the set of thirty-four features and the optimized feature subset as the input variables of the random forest classifier,the results show that the accuracy difference between the two feature classification schemes is small,but the classification effect of all feature sets is slightly better than the optimal feature subset.The overall classification accuracy of sample plots verification was 86%-95%,the Kappa coefficient was between 0.7 and 0.85,and the percentage error of the total area was 5.42%.The research demonstrates a reliable method for mapping a wide range of winter wheat planting area,and provides a good prospect for exploring the precise mapping of other crops,which is of great significance to crop monitoring and agricultural development.

Domesticated HERV-W env contributes to the activation of the small conductance Ca^(2+)-activated K^(+)type 2 channels via decreased 5-HT4 receptor in recent-onset schizophrenia

The human endogenous retroviruses type W family envelope(HERV-W env)gene is located on chromosome 7q21-22.Our previous studies show that HERV-W env is elevated in schizophrenia and HERV-W env can increase cal-cium influx.Additionally,the 5-HTergie system and particularly 5-hydroxytryptamine(5-HT)receptors play a prominent role in the pathogenesis and treatment of schizophrenia.5-hydroxytryptamine receptor 4(5-HT4R)agonist can block calcium channels.However,the underlying relationship between HERV-W env and 5-HT4R in the etiology of schizophrenia has not been revealed.Here,we used enzyme-linked immunosorbent assay to detect the concentration of HERV-W env and 5-HT4R in the plasma of patients with schizophrenia and we found that there were decreased levels of 5-HT4R and a negative correlation between 5-HT4R and HERV-W env in schizophrenia.Overexpression of HERV-W env decreased the transcription and protein levels of 5-HT4R but increased small conductance Ca^(2+)-activated K^(+)type 2 channels(SK2)expression levels.Further studies revealed that HERV-w env could interact with 5-HT4R.Additionally,luciferase assay showed that an essential region(-364 to-176 from the transcription start site)in the SK2 promoter was required for HERV-W env-induced SK2 expression.Importantly,5-HT4R participated in the regulation of SK2 expression and promoter activity.Electrophysiological recordings suggested that HERV-Wenv could increase SK2 channel currents and the increase of SK2 currents was inhibited by 5-HT4R.In condusion,HERV-W env could activate SK2 channels via decreased 5-HT4R,which might exhibit a novel mechanism for HERV-Wenv to influence neuronal activity in schizophrenia.

Effect of Sb-induced oxygen octahedral distortion on piezoelectric performance and thermal stability of Pb(In,Nb)O_(3)-Pb(Hf,Ti)O_(3)ceramics

The combination of excellent thermal stability and outstanding electrical performance is of great sig-nificance for piezoelectric ceramics.Herein,we have prepared 0.11Pb(In_(0.5)Nb_(0.5))O_(3)-0.89Pb(Hf_(0.47)Ti_(0.53))O_(3)-Sb_(2)O_(5)(PIN-PHT-x Sb)ceramics by solid-phase method and investigated the effect of oxygen octahedral lattice distortion on microstructure and macroscopic electrical properties.The distortion index of oxygen octahedra is studied by Rietveld refinement,showing that optimal octahedral distortion can soften B-O repulsion,disrupt long-range ordered ferroelectric domains,and enhance local heterogeneities,signifi-cantly increasing piezoelectric properties.Moreover,outstanding thermal stability and ultrahigh piezo-electric response of PIN-PHT-1.2Sb ceramics are realized under the synergistic influence of octahedral distortion,excellent density,and large grain size.Compared with PIN-PHT ceramics,PIN-PHT-1.2Sb ce-ramics exhibit ultrahigh piezoelectric responses(d_(33)=706 pC/N,k_(p)=0.68,ε_(r)=3244),a high Curie temperature(T C)of 300℃,excellent thermal stability,and anti-fatigue properties.