Selective capture of PM2.5 by urban trees: The role of leaf wax composition and physiological traits in air quality enhancement.

Human health risks from particles with a diameter of less than 2.5 µm (PM2.5) highlight the role of urban trees as bio-filters in air pollution control. However, whether the size and composition of particles captured by various tree species differ or not remain unclear. This study investigates how leaf attributes affect the capture of PM2.5, which can penetrate deep into the lungs and pose significant health risks. Using a self-developed particulate matter (PM) resuspension chamber and single-particle aerosol mass spectrometer, we measured the size distribution and mass spectra of particles captured by ten tree species. Notably, Cinnamomum camphora (L.) J.Presl and Osmanthus fragrans Lour. are more effective at capturing particles under 1 µm, which are most harmful because they can reach the alveoli, whereas Ginkgo biloba L. and Platanus × acerifolia (Aiton) Willd. tend to capture larger particles, up to 1.6 µm, which are prone to being trapped in the upper respiratory tract. Leaf physiological traits such as stomatal conductance and water potential significantly enhance the capture of larger particles. The Adaptive Resonance Theory neural network (ART-2a) algorithm classified a large number of single particles to determine their composition. Results indicate distinct inter-species variations in chemical composition of particles captured by leaves. Moreover, we identified how specific leaf wax compositions-beyond the known sticky nature of hydrophobic waxes-contribute to particle adhesion, particularly highlighting the roles of fatty acids and alkanes in adhering particles rich in organic carbon and heavy metals, respectively. This research advances our understanding by linking leaf physiological and wax characteristics to the selective capture of PM2.5, providing actionable insights for urban forestry management. The detailed exploration of particle size and composition, tied to specific tree species, enriches the current literature by quantifying how and why different species contribute variably to air quality improvement. This adds a crucial layer of specificity to the general knowledge that trees serve as bio-filters, offering a refined strategy for planting urban trees based on their particulate capture profiles.

Mapping the constituent preference of tree species for capturing particulate matter on leaf surfaces using single-particle mass spectrometry and supervised machine learning.

Respiratory health is negatively influenced by the dimensions and constituents of particulate matter (PM). Although mass concentration is widely acknowledged to be key to assessing dust retention by urban trees, the role of plant leaves in filtering PM from the urban atmosphere, particularly regarding the particle dimensions and chemical constituents of retained PM on the leaf, remains elusive. Here we combined single-particle aerosol mass spectrometry and a particle resuspension chamber to investigate how urban tree species capture PM constituents. Results indicate that leaves are efficient in capturing relatively larger particles (1.0-2.0 µm). Compositionally, airborne particles were mostly composed of elemental carbon (EC, 20%), organic carbon (OC, 17%), and secondary reaction products (13%). However, leaf surfaces revealed a preference for retaining crustal species, comprising 55% of captured particulates. Notably, specific tree species demonstrated varied affinities for different PM constituents: Osmanthus fragrans Lour. predominantly captured levoglucosan (LEV), indicative of its efficiency against biomass burning particles, whereas Cinnamomum camphora (L.) J.Presl and Sabina chinensis var. kaizuca W.C.Cheng & W.T.Wang were more effective in capturing heavy metals (HMs). XGBoost modelling identified indicator ions, e.g., CN-, NO3-, NO2-, PO3-, with SHAP values surpassing 0.035, suggesting a preferential adsorption of these ions among different tree species. These findings demonstrate that the particulate capture efficiency of urban tree species varies with species-specific leaf properties, particularly in their ability to selectively adsorb particles containing hazardous constituents such as LEV and HMs. This study provides a scientific basis for the strategic selection of tree species in urban forestry initiatives aimed at improving air quality and public health.

Selective Ligase-Based Sample Processing-Free Discrimination and Detection of Site-Specific DNA 5-Hydroxymethylcytosine.

Accurate detection of site-specific 5-hydroxymethylcytosine (5hmC) in genomic DNA is of great significance, but it is technically challenging to directly distinguish very low levels of 5hmC from their abundant cytosine/5-methylcytosine (C/5mC) analogues. Herein, we wish to propose a selective ligase-mediated mechanism (SLim) that can directly discriminate 5hmC from C/5mC with a high specificity without the use of any sample processing protocol. In this new design, we discovered that HiFi Taq DNA Ligase can well tolerate the mismatched 5hmC/A base-pairing and then effectively ligate the associated nicking site while the mismatched 5mC/A or C/A pairs cannot be recognized by HiFi Taq DNA Ligase, providing a new way for direct and selective discriminating 5hmC from its similar analogues. Ultrasensitive and selective quantification of site-specific 5hmC is realized by coupling the SLim with polymerase chain reaction (PCR) or loop-mediated isothermal amplification (LAMP).

Multilayered regulation and implication of flowering time in plants.

Initiation of flowering is a key switch for plants to shift from the vegetative growth to the phase of reproductive growth. This critical phase is essential not only for achieving successful reproduction, but also for facilitating environmental adaptation and maximizing yield potential. In the past decades, the environmental factors and genetic pathways that control flowering time have undergone extensive investigation in both model plant Arabidopsis and various crop species. The impact of environmental factors on plant flowering time is well documented. This paper focuses on the multilayered modulation of flowering time. Recent multi-omics approaches, and genetic screens have revealed additional components that modulate flowering time across various levels, encompassing chromatin modification, transcriptional and post-transcriptional control, as well as translational and post-translational regulation. The interplay between these various layers of regulation creates a finely-tuned system that can respond to a wide variety of inputs and allows plants to adjust flowering time in response to changing environmental conditions. In this review, we present a comprehensive overview of the recent progress made in understanding the intricate regulation of flowering time in plants, emphasizing the pivotal molecular components and their intricate interactions. Additionally, we provide an exhaustive list of key genes implicated in the intricate modulation of flowering time and offer a detailed summary of regulators of FLOWERING LOCUS T (FT) and FLOWERING LOCUS (FLC). We also discuss the implications of this knowledge for crop improvement and adaptation to changing environments.

Characterizing leaf-deposited particles: Single-particle mass spectral analysis and comparison with naturally fallen particles.

The size and composition of particulate matter (PM) are pivotal in determining its adverse health effects. It is important to understand PM's retention by plants to facilitate its atmospheric removal. However, the distinctions between the size and composition of naturally fallen PM (NFPM) and leaf-deposited PM (LDPM) are not well-documented. Here we utilize a single-particle aerosol mass spectrometer, coupled with a PM resuspension chamber, to analyze these differences. We find that LDPM particles are 6.8-97.3 % larger than NFPM. Employing a neural network algorithm based on adaptive resonance theory, we have identified distinct compositional profiles: NFPM predominantly consists of organic carbon (OC; 31.2 %) and potassium-rich components (19.1 %), whereas LDPM are largely composed of crustal species (53.9-60.6 %). Interestingly, coniferous species retain higher OC content (11.5-13.7 %) compared to broad-leaved species (0.5-1.2 %), while the levoglucosan content exhibit an opposite trend. Our study highlights the active role of tree leaves in modifying PM composition beyond mere passive capture, advocating for a strategic approach to species selection in urban greening initiatives to enhance PM mitigation. These insights provide guidance for urban planners and environmentalists in implementing nature-based solutions to improve urban air quality.

Rapeseed PP2C37 Interacts with PYR/PYL Abscisic Acid Receptors and Negatively Regulates Drought Tolerance.

Global water deficit is a severe abiotic stress threatening the yielding and quality of crops. Abscisic acid (ABA) is a phytohormone that mediates drought tolerance. Protein kinases and phosphatases function as molecular switches in eukaryotes. Protein phosphatases type 2C (PP2Cs) are a major family that play essential roles in ABA signaling and stress responses. However, the role and underlying mechanism of PP2C in rapeseed (Brassica napus L.) mediating drought response has not been reported yet. Here, we characterized a PP2C family member, BnaPP2C37, and its expression level was highly induced by ABA and dehydration treatments. It negatively regulates drought tolerance in rapeseed. We further identified that BnaPP2C37 interacted with multiple PYR/PYL receptors and a drought regulator BnaCPK5 (calcium-dependent protein kinase 5) through yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays. Specifically, BnaPYL1 and BnaPYL9 repress BnaPP2C37 phosphatase activity. Moreover, the pull-down assay and phosphatase assays show BnaPP2C37 interacts with BnaCPK5 to dephosphorylate BnaCPK5 and its downstream BnaABF3. Furthermore, a dual-luciferase assay revealed BnaPP2C37 transcript level was enhanced by BnaABF3 and BnaABF4, forming a negative feedback regulation to ABA response. In summary, we identified that BnaPP2C37 functions negatively in drought tolerance of rapeseed, and its phosphatase activity is repressed by BnaPYL1/9 whereas its transcriptional level is upregulated by BnaABF3/4.

Advances in membrane-tethered NAC transcription factors in plants.

Transcription factors are central components in cell signal transduction networks and are critical regulators for gene expression. It is estimated that approximately 10% of all transcription factors are membrane-tethered. MTFs (membrane-bound transcription factors) are latent transcription factors that are inherently anchored in the cellular membrane in a dormant form. When plants encounter environmental stimuli, they will be released from the membrane by intramembrane proteases or by the ubiquitin proteasome pathway and then were translocated to the nucleus. The capacity to instantly activate dormant transcription factors is a critical strategy for modulating diverse cellular functions in response to external or internal signals, which provides an important transcriptional regulatory network in response to sudden stimulus and improves plant survival. NTLs (NTM1-like) are a small subset of NAC (NAM, ATAF1/2, CUC2) transcription factors, which contain a conserved NAC domain at the N-terminus and a transmembrane domain at the C-terminus. In the past two decades, several NTLs have been identified from several species, and most of them are involved in both development and stress response. In this review, we review the reports and findings on NTLs in plants and highlight the mechanism of their nuclear import as well as their functions in regulating plant growth and stress response.

Uneven PM2.5 dispersion pattern across an open-road vegetation barrier: Effects of planting combination and wind condition.

The increased traffic-induced emissions contribute to the exacerbation of airborne particulate matter (PM) pollution. The vegetation barrier (VB) provides a means of reducing the traffic-induced pollutants. However, the effects of VB configuration and local environment on PM dispersion and reduction remain unclear, and thereby needs further advancement on VB design and characteristics. This study constructed a 3D numerical model based on field survey in an open-road VB of Shanghai urban area, and then simulated PM2.5 dispersion under various VB configurations and wind conditions. The results consolidated that the presence of the VB reduced PM2.5 concentration by over 15 % across the VB. A greater bush coverage (2/3 and more) reduces over 14 % more PM2.5 pollution across the VB than that for a greater arbor coverage, and reduces 6 % more PM2.5 pollution in the sidewalk canyon. Given a certain bush planting coverage, planting bushes in the windward area is beneficial to the overall PM2.5 reduction by approximately 4-14 %. The wind directions determine the overall pattern of PM2.5 dispersion across the VB plot, decreasing trends for perpendicular winds but fluctuating curves for parallel winds Wind velocities largely contribute to the changing rates of PM2.5 concentration, the increased wind speed from 1 m/s to 7 m/s accumulated 5-11 % more PM2.5 pollution across the VB plot. This study provides practical insights for effective VB designs in order to mitigate the PM pollution and the human's exposure to PM2.5 in urban open-road environments.

Design of iron oxyhydroxide nanosheets coated on Co species embedded in nanoporous carbon for oxygen evolution reaction.

There is still a tremendous challenge in designing environmentally friendly oxygen evolution reaction (OER) catalysts that are inexpensive and high-performing for practical applications. Herein, the self-sacrificing template zeolitic imidazolate framework-67 (ZIF-67) was pyrolyzed under N2 atmosphere to generate Co species embedded in nanoporous carbon (Co-NC). Then, iron oxyhydroxide (FeOOH) was wrapped onto the Co-NC surface via electrodeposition to shape the Co-NC@FeOOH composites. Benefiting from the core-shell structure, high conductivity, and distributed active sites, Co-NC@FeOOH presents distinguished OER performance with a low overpotential (336 mV) at 10 mA cm-2 and small Tafel slope (49.46 mV dec-1). This work furnishes a rosy passage for receiving cost-effective electrocatalysts with high efficiency for OER.

The role of maternal age on adverse pregnancy outcomes among primiparous women with singleton birth: a retrospective cohort study in urban areas of China.

BACKGROUND: Both young and advanced maternal age pregnancies have strong associations with adverse pregnancy outcomes; however, there is limited understanding of how these associations present in an urban environment in China. This study aimed to analyze the associations between maternal age and pregnancy outcomes among Chinese urban women. METHODS: We performed a population-based study consisting of 60,209 singleton pregnancies of primiparous women whose newborns were delivered after 20 weeks' gestation between January 2012 and December 2015 in urban areas of China. Participants were divided into six groups (19 or younger, 20-24, 25-29, 30-34, 35-39, 40 or older). Pregnancy outcomes include gestational diabetes mellitus (GDM), preeclampsia, placental abruption, placenta previa, premature rupture of membrane (PROM), postpartum hemorrhage, preterm birth, low birthweight, small for gestational age (SGA), large for gestational age (LGA), fetal distress, congenital microtia, and fetal death. Logistic regression models were used to assess the role of maternal age on the risk of adverse pregnancy outcomes with women aged 25-29 years as the reference group. RESULTS: The risks of GDM, preeclampsia, placenta previa, and postpartum hemorrhage were decreased for women at a young maternal age and increased for women with advanced maternal age. Both young and advanced maternal age increased the risk of preterm birth and low birthweight. Young maternal age was also associated with increased risk of SGA (aOR 1.64, 95% CI 1.46-1.83) and fetal death (aOR 2.08, 95% CI 1.35-3.20). Maternal age over 40 years elevated the odds of placental abruption (aOR 3.44, 95% CI 1.47-8.03), LGA (aOR 1.47, 95% CI 1.09-1.98), fetal death (aOR 2.67, 95% CI 1.16-6.14), and congenital microtia (aOR 13.92, 95% CI 3.91-49.57). There were positive linear associations between maternal age and GDM, preeclampsia, placental abruption, placenta previa, PROM, postpartum hemorrhage, preterm birth, LGA and fetal distress (all P for linear trend < .05), and a negative linear association between maternal age and SGA (P for linear trend < .001). The analysis of the associations between maternal age and adverse fetal outcomes showed U-shape for preterm birth, low birth weight, SGA, fetal death and congenital microtia (all P for quadratic trend < .001). CONCLUSIONS: Advanced maternal age predisposes women to adverse obstetric outcomes. Young maternal age manifests a bidirectional effect on adverse pregnancy outcomes. The findings may contribute to improving women's antenatal care and management.

Early peripheral blood lymphocyte subsets and cytokines in predicting the severity of influenza B virus pneumonia in children.

Background: Children with influenza B virus infection have a higher susceptibility and higher severity of illness. The activation and disorder of immune function play an important role in the severity of influenza virus infection. This study aims to investigate whether early lymphocyte count and cytokines can provide predictive value for the progression in children with influenza B virus pneumonia. Methods: A retrospective cohort study was conducted to analyze the clinical data of children with influenza B virus pneumonia from December 1, 2021, to March 31, 2022, in the National Children's Regional Medical Center (Shengjing Hospital of China Medical University). According to the severity of the disease, the children were divided into a mild group and a severe group, and the clinical characteristics, routine laboratory examination, lymphocyte subsets, and cytokines were compared. Results: A total of 93 children with influenza B virus pneumonia were enrolled, including 70 cases in the mild group and 23 cases in the severe group. Univariate analysis showed that drowsiness, dyspnea, white blood cell (WBC), lymphocytes, monocytes, procalcitonin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase-MB (CK-MB), lactate dehydrogenase (LDH), fibrinogen (FIB), Immunoglobulin M (IgM), lung consolidation, total T cell count, CD4+ T cell count, CD8+ T cell count, NK cell count, NK cell % and B cell % had statistical differences between the mild and severe groups (P<0.05). In multivariate logistic regression analysis, reduced ALT (OR = 1.016), FIB (OR = 0.233), CD8+ T cell count (OR = 0.993) and NK cell count (OR = 0.987) were independently associated with the development of severe influenza B virus pneumonia. Conclusions: The levels of T lymphocytes and NK cells were related to the progression of influenza B virus pneumonia in children, and the reduction of CD8+ T cell count and NK cell count can be used as independent risk factors for predicting the severity of influenza B virus pneumonia.

Effect of gestational diabetes mellitus on pregnancy outcomes among younger and older women and its additive interaction with advanced maternal age.

Background: The prevalence of gestational diabetes mellitus (GDM) and advanced maternal age (AMA, ≥ 35 years) has shown an increasing trend worldwide. This study aimed to evaluate the risk of pregnancy outcomes among younger (20-34 years) and older (≥ 35 years) women with GDM and further analyze the epidemiologic interaction of GDM and AMA on these outcomes. Methods: This historical cohort study included 105 683 singleton pregnant women aged 20 years or older between January 2012 and December 2015 in China. Stratified by maternal age, the associations between GDM and pregnancy outcomes were analyzed by performing logistic regression. Epidemiologic interactions were assessed by using relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), and synergy index (SI) with their 95% confidence intervals (95%CIs). Results: Among younger women, individuals with GDM had a higher risk of all maternal outcomes, preterm birth (relative risk [RR] 1.67, 95%CI 1.50-1.85), low birthweight (RR 1.24, 95%CI 1.09-1.41), large for gestational age (RR 1.51, 95%CI 1.40-1.63), macrosomia (RR 1.54, 95%CI 1.31-1.79), and fetal distress (RR 1.56, 95%CI 1.37-1.77) than those without GDM. Among older women, GDM increased the risk of gestational hypertension (RR 2.17, 95%CI 1.65-2.83), preeclampsia (RR 2.30, 95%CI 1.81-2.93), polyhydramnios (RR 3.46, 95%CI 2.01-5.96), cesarean delivery (RR 1.18, 95%CI 1.10-1.25), preterm birth (RR 1.35, 95%CI 1.14-1.60), large for gestational age (RR 1.40, 95%CI 1.23-1.60), macrosomia (RR 1.65, 95%CI 1.28-2.14) and fetal distress (RR 1.46, 95%CI 1.12-1.90). Additive interactions of GDM and AMA on polyhydramnios and preeclampsia were found, with RERI of 3.11 (95%CI 0.05-6.16) and 1.43 (95%CI 0.09-2.77), AP of 0.51 (95%CI 0.22-0.80) and 0.27 (95%CI 0.07-0.46), and SI of 2.59 (95%CI 1.17-5.77) and 1.49 (95%CI 1.07-2.07), respectively. Conclusion: GDM is an independent risk factor for multiple adverse pregnancy outcomes, and may exert additive interactions with AMA on the risk of polyhydramnios and preeclampsia.

Decoupling between carbon source and sink induced by responses of daily stem growth to water availability in subtropical urban forests.

Urban forests are anticipated to offer sustainable ecosystem services, necessitating a comprehensive understanding of the ways in which trees respond to environmental changes. This study monitored stem radius fluctuations in Cinnamomum camphora and Taxodium distichum var. imbricatum trees using high-resolution dendrometers at two sites, respectively. Gross primary production (GPP) was measured using eddy-covariance techniques and aggregated to daily sums. Hourly and daily stem radius fluctuations were estimated across both species, and the responses of stems to radiation (Rg), air temperature (Tair), vapor pressure deficit (VPD), and soil humidity (SoilH) were quantified using Bayesian linear models. The diel growth patterns of the monitored trees showed similar characteristics at the species level. Results revealed that trees growth occurred primarily at night, with the lowest hourly contribution to total growth and probability for growth occurring in the afternoon. Furthermore, the Bayesian models indicated that VPD was the most important driver of daily growth and growth probability. After considering the potential constraints imposed by VPD, a modified Gompertz equation showed good performance, with R2 ranging from 0.94 to 0.99 for the relationship between accumulative growth and time. Bayes-based model-independent data assimilation using advanced Markov chain Monte Carlo (MCMC) algorithms provided deeper insights into nonlinear model parameterization. Finally, the quantified relationship between GPP and stem daily growth revealed that the decoupling between carbon source and sink increased with VPD. These findings provided direct empirical evidence for VPD as a key driver of daily growth patterns and raise questions about carbon neutrality accounting under future climate change given the uncertainties induced by increased water stress limitations on carbon utilization.

The abscisic acid-responsive element binding factors MAPKKK18 module regulates abscisic acid-induced leaf senescence in Arabidopsis.

The mitogen-activated protein kinase kinase kinase 18 (MAPKKK18) has been reported to play a role in abiotic stress priming in long-term abscisic acid (ABA) response including drought tolerance and leaf senescence. However, the upstream transcriptional regulators of MAPKKK18 remain to be determined. Here, we report ABA-responsive element binding factors (ABFs) as upstream transcription factors of MAPKKK18 expression. Mutants of abf2, abf3, abf4, and abf2abf3abf4 dramatically reduced the transcription of MAPKKK18. Our electrophoresis mobility shift assay and dual-luciferase reporter assay demonstrated that ABF2, ABF3, and ABF4 bound to ABA-responsive element cis-elements within the promoter of MAPKKK18 to transactivate its expression. Furthermore, enrichments of the promoter region of MAPKKK18 by ABF2, ABF3, and ABF4 were confirmed by in vivo chromatin immunoprecipitation coupled with quantitative PCR. In addition, we found that mutants of mapkkk18 exhibited obvious delayed leaf senescence. Moreover, a genetic study showed that overexpression of ABF2, ABF3, and ABF4 in the background of mapkkk18 mostly phenocopied the stay-green phenotype of mapkkk18 and, expression levels of five target genes of ABFs, that is, NYE1, NYE2, NYC1, PAO, and SAG29, were attenuated as a result of MAPKKK18 mutation. These findings demonstrate that ABF2, ABF3, and ABF4 act as transcription regulators of MAPKKK18 and also suggest that, at least in part, ABA acts in priming leaf senescence via ABF-induced expression of MAPKKK18.

Coagulation effect of atmospheric submicron particles on plant leaves: Key functional characteristics and a comparison with dry deposition.

Submicron particles have become a new focus in research on air pollution control. The abilities of urban tree species to retain particles can be used to alleviate urban haze pollution. However, research has focused mostly on plants and environmental conditions rather than on particle itself. Particle migration and transformation at the leaf-air interface are the key to dust retention. Submicron particles coagulate when they are retained by leaves. In this study, NaCl was used to simulate submicron particles. The average sizes of the particles on the leaves of 10 greening tree species in Shanghai in different seasons were measured using the sweep-resuspension method to characterize the coagulation effect. Thereafter, the effects of leaf characteristics were investigated and analyzed in relation to dry deposition velocity. The results indicated that the particles on the leaves of Ginkgo biloba, Osmanthus fragrans, Sabina chinensis (L.) Ant. "Kaizuca," Cinnamomum camphora, and Metasequoia glyptostroboides were large. The seasonal variability of the sizes of the particles on the leaves of different tree species varied. The average particle size was positively correlated with wax content and negatively correlated with single leaf area; however, the other factors correlated with particle size varied by season. For example, in April, the average particle size was positively correlated with tensile strength, wind resistance, adaxial epidermal roughness, and water potential, whereas the effects of stomatal conductance were more complex. Non-significant correlation was identified between coagulation and dry deposition although both were positively correlated with roughness and wax content. This study explored the effects of leaf characteristics on coagulation. The results may serve as a theoretical foundation for explaining the microscopic process underlying dust retention in plants and may provide a clearer scientific basis for the prevention and control of submicron particle pollution and the selection of urban greening tree species.

ANAC087 transcription factor positively regulates age-dependent leaf senescence through modulating the expression of multiple target genes in Arabidopsis.

Leaf senescence is the final stage of leaf development and appropriate onset and progression of leaf senescence are critical for reproductive success and fitness. Although great progress has been made in identifying key genes regulating leaf senescence and elucidating the underlining mechanisms in the model plant Arabidopsis, there is still a gap to understanding the complex regulatory network. In this study, we discovered that Arabidopsis ANAC087 transcription factor (TF) positively modulated leaf senescence. Expression of ANAC087 was induced in senescing leaves and the encoded protein acted as a transcriptional activator. Both constitutive and inducible overexpression lines of ANAC087 showed earlier senescence than control plants, whereas T-DNA insertion mutation and dominant repression of the ANAC087 delayed senescence rate. A quantitative reverse transcription-polymerase chain reaction (qRT-PCR) profiling showed that the expression of an array of senescence-associated genes was upregulated in inducible ANAC087 overexpression plants including BFN1, NYE1, CEP1, RbohD, SAG13, SAG15, and VPEs, which are involved in programmed cell death (PCD), chlorophyll degradation and reactive oxygen species (ROS) accumulation. In addition, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-qPCR) assays demonstrated that ANAC087 directly bound to the canonical NAC recognition sequence (NACRS) motif in promoters of its target genes. Moreover, mutation of two representative target genes, BFN1 or NYE1 alleviated the senescence rate of ANAC087-overexpression plants, suggesting their genetic regulatory relationship. Taken together, this study indicates that ANAC087 serves as an important regulator linking PCD, ROS, and chlorophyll degradation to leaf senescence.

Sleep cycle in children with severe acute bronchopneumonia during mechanical ventilation at different depths of sedation.

BACKGROUND: To investigate the characteristics of sleep cycle in children with severe acute bronchopneumonia treated with invasive mechanical ventilation at different sedation depths. METHODS: We included 35 pediatric patients with severe acute bronchopneumonia treated using mechanical ventilation in Pediatric Intensive Care Unit of Shengjing Hospital of China Medical University. They were divided into deep sedation group (n = 21; ramsay score 5-6) and light sedation group (n = 14; ramsay score3-4) based on sedation depth achieved during mechanical ventilation. Long-term video electroencephalography (EEG) monitoring was performed within the first 24 h after starting mechanical ventilation and after weaning from mechanical ventilation and discontinuing sedatives and analgesics. The results were analyzed and compared with those of normal children to analyze changes in sleep cycle characteristics at different sedation depths and mechanical ventilation stages. RESULTS: There were 29 cases altered sleep architecture. The deep sedation group had a significantly higher incidence of sleep architecture altered, total sleep duration, and non-rapid eye movement sleep-1 (NREM-1) loss incidence than the light sedation group. Moreover, the deep sedation group had a significantly lower awakening number and rapid eye movement sleep (REM) percentage than the light sedation group. The sleep cycle returned to normal in 27 (77%) patients without NREM-1 or REM sleep loss. CONCLUSIONS: Deep sedation during mechanical ventilation allows longer total sleep duration, fewer awakenings, and an increased deep sleep proportion, but sleep architecture is severely altered. After weaning from mechanical ventilation and sedative discontinuation, lightly sedated children exhibit better sleep recovery.

A high-resolution study of PM2.5 accumulation inside leaves in leaf stomata compared with non-stomatal areas using three-dimensional X-ray microscopy.

Plant leaves retain atmospheric particulate matter (PM) on their surfaces, helping PM removal and risk reduction of respiratory tract infection. Several processes (deposition, resuspension, rainfall removal) can influence the PM accumulation on leaves and different leaf microstructures (e.g., trichomes, epicuticular waxes) can also be involved in retaining PM. However, the accumulation and distribution of PM on leaves, particularly at the stomata, are unclear, and the lack of characterization methods limits our understanding of this process. Thus, in this study, we aimed to explore the pathway through which PM2.5 (aerodynamic diameter ≤ 2.5 µm) enters plant leaves, and the penetration depth of PM2.5 along the entry route. Here, an indoor experiment using diamond powder as a tracer to simulate PM2.5 deposition on leaves was carried out. Then, the treated and non-treated leaves were scanned by using three-dimensional (3D) X-ray microscopy. Next, the grayscale value of the scanned images was used to compare PM2.5 accumulation in stomatal and non-stomatal areas of the treated and non-treated leaves, respectively. Finally, a total PM2.5 volume from the abaxial epidermis was calculated. The results showed that, first, a large amount of PM2.5 accumulates within leaf stomata, whereas PM2.5 does not accumulate at non-stomatal areas. Then, the penetration depth of PM2.5 in stomata of most tree species was 5-14 µm from the abaxial epidermis. For the first time, 3D X-ray microscope scanning was used to confirm that a pathway by which PM2.5 enters the leaves is through the stomata, which is fundamental for further research on how PM2.5 translocates and interacts with tissues and cells in leaves.

Quantifying the capacity of tree branches for retaining airborne submicron particles.

Human health risks brought by fine atmospheric particles raise scholarly and policy awareness about the role of urban trees as bio-filters of air pollution. While a large number of empirical studies have focused on the characteristics of vegetation leaves and their effects on atmospheric particle retention, the dry deposition of particles on branches, which plays a significant role in capturing and retaining particles during the defoliation period and contributes substantially to total removal of atmospheric particles, is under-investigated. To fill in this knowledge gap, this case study examined the dry deposition velocities (Vd) of submicron particulate matters (PM1) on the branches of six common deciduous species in Shanghai (China) using laboratory experiments. And the association between Vd and key branch anatomical traits (including surface roughness, perimeter, rind width proportion, lenticel density, peeling, and groove/ridge characteristics) was explored. It was found that surface roughness would increase Vd, as a rougher surface significantly increases turbulence, which is conducive to particle diffusion. By contrast, peeling, branch perimeter, and lenticel density would decrease Vd. Peeling represents the exfoliated remains on the branch surfaces which may flutter considerably with airflow, leading to particle resuspension and low Vd. When branch perimeter increases, the boundary layer of branches thickens and a wake area appears, increasing the difficulty of particles to reach branch surface, and reducing Vd. While lenticels can increase the roughness of branch surface, their pointy shape would uplift airflow and cause a leeward wake area, lowering Vd. This finely wrought study contributes to a better understanding of branch dry deposition during leaf-off seasons and potential of deciduous trees serving as nature-based air filters all year round in urban environments.

Rapeseed NAM transcription factor positively regulates leaf senescence via controlling senescence-associated gene expression.

Leaf senescence is one of the most visible forms of programmed cell death in plants. It can be a seasonal adaptation in trees or the final stage in crops ensuring efficient translocation of nutrients to seeds. Along with developmental cues, various environmental factors could also trigger the onset of senescence through transcriptional cascades. Rapeseed (Brassica napus L.) is an important oil crop with its yielding affected by significant falling leaves as a result of leaf senescence, compared to many other crops. Therefore, a better understanding of leaf senescence and developing strategies controlling the progress of leaf senescence in rapeseed is necessary for warranting vegetable oil security. Here we functionally characterized the gene BnaNAM encoding No Apical Meristem (NAM) homologue to identify transcriptional regulation of leaf senescence in rapeseed. A combination of transient and stable expression techniques revealed overexpression of BnaNAM induced ROS production and leaf chlorosis. Quantitative evaluation of up-regulated genes in BnaNAM overexpression lines identified genes related to ROS production (RbohD, RbohF), proteases (ßVPE, γVPE, SAG12, SAG15), chlorophyll catabolism (PaO, PPH) and nucleic acid degradation (BFN1) as the putative downstream targets. A dual luciferase-based transcriptional activation assay of selected promoters further confirmed BnaNAM mediated transactivation of promoters of the downstream genes. Finally, an electrophoretic mobility shift assay further confirmed direct binding of BnaNAM to promoters of ßVPE, γVPE, SAG12, SAG15 and BFN1. Our results therefore demonstrate a novel role of BnaNAM in leaf senescence.