It is imperative to derive an appropriate cadmium （Cd） health risk toxicity threshold for paddy soils to ensure the Cd con- centration of rice grains meet the food safety standard. In this study, 20 ...rice cultivars from the main rice producing areas in China were selected, and a pot-experiment was conducted to investigate transformation of Cd in paddy soil-rice system with 0 （CK）, 0.3 mg kg-1 （T1） and 0.6 mg kg-1（T2） Cd treatments in greenhouse. The results showed that Cd concentrations of rice grains existed significant difference （P〈0.05） in 20 rice cultivars under the same Cd level in soil. The Cd concentrations of rice grains of the CK, T1 and T2 treatments were in the range of 0.143-0.202, 0.128-0.458 and 0.332-0.806 mg kg-1, respectively. Marked differences of the ratios of Cd concentration for soil to rice grain （BCFs） and transfer factors （TFs, root to grain and straw to grain） among the tested cultivars were observed in this study. The bioconcentration factors （BCFgrain） and TFs of the 20 rice cultivars were 0.300-1.112 and 0.342-0.817, respectively. The TFs of Cd from straw to grain ranged from 0.366 to 1.71, with significant differences among these 20 rice cultivars. The bioconcentration factors （BCFgrain） and TFs among the 20 rice cultivars ranged from 0.300-1.112 and 0.342-0.817, respectively. The species-sensitivity distribu- tion （SSD） of Cd sensitivity of the rice species could be fitted well with Burr-Ill （R2=0.987） based on the data of BCFs. The toxicity threshold of Cd derived from SSD for the paddy soil was 0.507 mg kg-1 in the present study.
The cell‐to‐cell transfer of α‐synuclein (α‐Syn) greatly contributes to Parkinson's disease (PD) pathogenesis and underlies the spread of α‐Syn pathology. During this process, extracellular α‐Syn can ...activate microglia and neuroinflammation, which plays an important role in PD. However, the effect of extracellular α‐Syn on microglia autophagy is poorly understood. In the present study, we reported that extracellular α‐Syn inhibited the autophagy initiation, as indicated by LC3‐II reduction and p62 protein elevation in BV2 and cultured primary microglia. The in vitro findings were verified in microglia‐enriched population isolated from α‐Syn‐overexpressing mice induced by adeno‐associated virus (AAV2/9)‐encoded wildtype human α‐Syn injection into the substantia nigra (SN). Mechanistically, α‐Syn led to microglial autophagic impairment through activating toll‐like receptor 4 (Tlr4) and its downstream p38 and Akt‐mTOR signaling because Tlr4 knockout and inhibition of p38, Akt as well as mTOR prevented α‐Syn‐induced autophagy inhibition. Moreover, inhibition of Akt reversed the mTOR activation but failed to affect p38 phosphorylation triggered by α‐Syn. Functionally, the in vivo evidence showed that lysozyme 2 Cre (Lyz2cre)‐mediated depletion of autophagy‐related gene 5 (Atg5) in microglia aggravated the neuroinflammation and dopaminergic neuron losses in the SN and exacerbated the locomotor deficit in α‐Syn‐overexpressing mice. Taken together, the results suggest that extracellular α‐Syn, via Tlr4‐dependent p38 and Akt‐mTOR signaling cascades, disrupts microglial autophagy activity which synergistically contributes to neuroinflammation and PD development.
Autophagy‐dependent and independent machinery synergistically contribute to hα‐Syn‐caused neuroinflammation in PD. The basal autophagy activity restricts microglia inflammation. Extracellular hα‐Syn interacts with and activates Tlr4, resulting in inflammatory responses, as well as autophagy suppression in microglia via Tlr4‐dependent p38 and Akt/mTOR signaling cascades. This impairs the inhibitory effect of autophagy on inflammation, and thus aggravating hα‐Syn‐induced inflammatory responses.
Aim: The productivity, functioning and biogeochemical cycles of terrestrial ecosystems are strongly affected by leaf element concentrations. Understanding the biological and ecological factors ...affecting leaf element concentrations is therefore important for modelling the productivity and nutrient fluxes of ecosystems and their responses to global change. The present study aimed to determine how leaf element concentrations are linked to taxonomy and the environment. Location: China. Methods: The concentrations of 10 leaf elements of 702 terrestrial plant species from different biomes were extracted from publications. The links between environmental variables, taxonomy and leaf elements were analyzed using phylogenetically comparative methods and partial Mantel tests. Results: Taxonomy had stronger effects on leaf S and SiO 2 than latitude, explaining 40.2—43.9% of total variation, whereas latitude had stronger effects on leaf N, P, K, Fe, Al, Mn, Na and Ca concentrations, explaining 19.5—52.1% of total variation. Leaf N, S, Al, Fe and Na concentrations were correlated with mean annual precipitation (MAP), while leaf N, P and Fe concentrations were correlated with mean annual temperature (MAT). Latitude, MAP and MAT were significantly correlated with the first axis of a principal components analysis (PCA). This first axis was associated with leaf elements involved in protein synthesis and photosynthesis. The other PCA axes, which were not correlated with MAT, latitude and MAP, were associated with leaf elements responsible for cell structure and enzymes. Main conclusions: Leaf element concentrations of terrestrial plants in China were correlated with climate, latitude and taxonomy. With the exception of S and SiO 2 , the environmental factors were more important in explaining leaf element variation than taxonomy. Therefore, changes in temperature and precipitation will directly affect the spatial patterns of leaf elements and thus the associated nutrient fluxes and ecosystem functioning.
Resurrection plants could survive severe drought stress, but the underlying mechanism for protecting their photosynthetic apparatus against drought stress is unclear. Cyclic electron flow (CEF) has ...been documented as a crucial mechanism for photoprotection in Arabidopsis and tobacco. We hypothesized that CEF plays an important role in protecting photosystem I (PSI) and photosystem II (PSII) against drought stress for resurrection plants. To address this hypothesis, the effects of mild drought stress on light energy distribution in PSII and P700 redox state were examined in a resurrection plant Paraboea rufescens. Cyclic electron flow was not activated below the photosynthetic photon flux density (PPFD) of 400 µmol m⁻² s⁻¹ in leaves without drought stress. However, CEF was activated under low light in leaves with mild drought stress, and the effective quantum yield of PSII significantly decreased. Meanwhile, non-photochemical quenching (NPQ) was significantly stimulated not only under high light but also under low light. Compared with the control, the fraction of overall P700 that cannot be oxidized in a given state (PSI acceptor side limitation) under high light was maintained at low level of 0.1 in leaves with water deficit, indicating that the over-reduction of the PSI acceptor side was prevented by the significant stimulation of CEF. Furthermore, methyl viologen could significantly increase the PSII photo-inhibition induced by high light compared with chloramphenicol. These results suggested that CEF is an important mechanism for protecting PSI and PSII from drought stress in resurrection plants.
Both leaf attributes and stomatal traits are linked to water economy in land plants. However, it is unclear whether these two components are associated evolutionarily.
In characterizing the possible ...effect of phylogeny on leaf attributes and stomatal traits, we hypothesized that a correlated evolution exists between the two. Using a phylogenetic comparative method, we analyzed 14 leaf attributes and stomatal traits for 17 species in Paphiopedilum. Stomatal length (SL), stomatal area (SA), upper cuticular thickness (UCT), and total cuticular thickness (TCT) showed strong phylogenetic conservatism whereas stomatal density (SD) and stomatal index (SI) were significantly convergent. Leaf vein density was correlated with SL and SD whether or not phylogeny was considered. The lower epidermal thickness (LET) was correlated positively with SL, SA, and stomatal width but negatively with SD when phylogeny was not considered. When this phylogenetic influence was factored in, only the significant correlation between SL and LET remained.
Our results support the hypothesis for correlated evolution between stomatal traits and vein density in Paphiopedilum. However, they do not provide evidence for an evolutionary association between stomata and leaf thickness. These findings lend insight into the evolution of traits related to water economy for orchids under natural selection.
Ferns usually have relatively lower photosynthetic potential than angiosperms. However, it is unclear whether low photosynthetic potential of ferns is linked to leaf water supply. We hypothesized ...that there is an evolutionary association of leaf water transport capacity with photosynthesis and stomatal density in ferns. In the present study, a series of functional traits relating to leaf anatomy, hydraulics and physiology were assessed in 19 terrestrial and 11 epiphytic ferns in a common garden, and analyzed by a comparative phylogenetics method. Compared with epiphytic ferns, terrestrial ferns had higher vein density (Dvein), stomatal density (SD), stomatal conductance (gs), and photosynthetic capacity (Amax), but lower values for lower epidermal thickness (LET) and leaf thickness (LT). Across species, all traits varied significantly, but only stomatal length (SL) showed strong phylogenetic conservatism. Amax was positively correlated with Dvein and gs with and without phylogenetic corrections. SD correlated positively with Amax, Dvein and gs, with the correlation between SD and Dvein being significant after phylogenetic correction. Leaf water content showed significant correlations with LET, LT, and mesophyll thickness. Our results provide evidence that Amax of the studied ferns is linked to leaf water transport capacity, and there was an evolutionary association between water supply and demand in ferns. These findings add new insights into the evolutionary correlations among traits involving carbon and water economy in ferns.
1. Stem xylem characteristics have a great impact on growth and adult stature of trees because of their role in mechanical support, long‐distance water transport and whole‐plant carbon allocation. ...Yet, despite the potential causal link between xylem traits and plant growth/adult stature, most studies have tried to link wood density, an indirect but easy to measure proxy for wood properties, to tree growth and size. 2. To determine whether xylem traits outperform wood density as predictors of tree growth and stature, we evaluated the covariation among wood density, xylem anatomical traits, tree diameter growth rate and adult stature in 40 Asian tropical tree species through principal component analyses and through bivariate correlation, both across species and across phylogenetically independent contrasts. 3. Vessel diameter exhibited a tight negative relationship with vessel frequency. Wood density showed a significant correlation with vessel diameter and density, but not with vessel fraction. Most correlations between functional traits indicate adaptive coordination, demonstrated by significant correlations between phylogenetically independent contrasts. 4. Across species, diameter growth rate and adult stature were positively correlated with vessel lumen diameter and potential hydraulic conductivity, but not with wood density. Thus, our results suggest that xylem anatomical traits that are linked to hydraulic conductivity are better predictors of tree growth rate and adult stature than wood density. 5. Synthesis. We found that xylem anatomical traits have a more significant influence on whole‐plant performance due to their direct association with stem hydraulic conductivity, whereas wood density is decoupled from hydraulic function due to complex variations in xylem components.
•Plasma and striatal sulfide levels were decreased in MPTP-induced PD mouse model.•CBS expression was reduced in the striatum and glial cells of MPTP-treated mice.•Striatal CBS overexpression rescued ...MPTP-induced motor deficits and DA neuron losses.•CBS overexpression reduced the MPTP-induced nitrative stress and α-syn nitration.•Glia CBS overexpression offered both direct and indirect protection to DA neurons.
Hydrogen sulfide (H2S), a novel neuromodulator, is linked to the pathogenesis of several neurodegenerative disorders. Exogenous application of H2S exerts neuroprotection via anti-inflammation and anti-oxidative stress in animal and cellular models of Parkinson’s disease (PD). However, the role of endogenous H2S and the contribution of its various synthases in PD remain unclear. In the present study, we found a decline of plasma and striatal sulfide level in 1-methy-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced PD mouse model. Interestingly, among the three H2S generating enzymes, only cystathionine β-synthase (CBS) expression was largely reduced in the striatum of MPTP-treated mice. The in vitro study confirmed a significant decrease of CBS expression in 1-methyl-4-phenylpyridinium (MPP+)-stimulated astrocytes and microglia, but not in neurons or SH-SY5Y dopaminergic cells. Striatal CBS overexpression, elicited by stereotaxic delivery with Cbs gene using recombinant adeno-associated-virus (rAAV-Cbs), successfully enhanced the sulfide level in the striatum and partially rescued the MPTP-induced dopaminergic neurotoxicity in the midbrain. Specifically, striatal CBS overexpression alleviated the motor deficits and dopaminergic neuron losses in the nigro-striatal pathway, with a concomitant inhibition of glial activation in MPTP-treated mice. Furthermore, compared to rAAV-Vector, rAAV-Cbs injection reduced the aberrant accumulation of nitric oxide and 3-nitrotyrosine (an indicator of protein nitration) in the striatum of MPTP-treated mice. Notably, it also attenuated the increase of nitrated α-synuclein level in MPTP mice. The in vitro study demonstrated that lentivirus-mediated CBS overexpression elevated the sulfide generation in glial cells. Moreover, glial CBS overexpression offered protection to midbrain dopaminergic neurons through repressing nitric oxide overproduction in both glial and neuronal cells induced by MPP+. Taken together, our data suggest that impaired CBS-H2S axis may contribute to the pathogenesis of PD, and that modulation of this axis may become a novel therapeutic approach for PD.
A carefully performed phytochemical investigation of the roots of Stemona mairei (Stemonaceae) led to the discovery of six so far undescribed dihydrostilbene dimers maistilbene A–F and four monomers ...maistilbene G–J. This is the first report of stilbenoids of this plant species and the first report of dimeric dihydrostilbenes from this plant family. The absolute configuration of these compounds was determined by a combination of Mo2(AcO)4-induced ECD spectra and quantum chemical calculation of NMR chemical shift, ECD and spin-spin coupling constants. Maistilbene G could increase the glucose consumption in L6 myotubes, disclosing a new hypoglycemic candidate.
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•Six undescribed dihydrostilbene dimers and four monomers were isolated from roots of Stemona mairei.•The absolute configuration was determined by a quantum chemical calculation of NMR, ECD and coupling constants.•Maistilbene G could increase the glucose consumption in L6 myotubes model.
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•A flexible heat-resistant variable density point pressure sensing array based on Ti3C2Tx-MXene with wide sensing range (7.2 Pa–15,000 kPa) has been developed.•The MXene nanosheets ...achieve firm adhesion without crosslinkers by introducing polar oxygen-containing functional groups.•The sensing mechanism of seven linear high sensitivity (0.14–0.87 kPa−1) in the pressure sensing process was revealed.•Large-area fully woven pressure sensing arrays vary the weave density to achieve precise control of resolution.
Wearable flexible pressure sensors are a novel class of human activity detection device. However, the preparation of pressure sensors with high sensitivity and wide sensing range still faces great challenges. This study reveals an flexible heat-resistant variable density point pressure sensing array (PSA) with ultra-wide sensing range based on Ti3C2Tx-MXene. MXene containing polar oxygen-containing functional groups coated polyester fiber fabricated the pressure sensing layer while a stainless steel wire core is used as a flexible electrode for signal collection. The signal processing device rapidly converts the mechanical signal into electrical signal output to increase the transmission speed and range. Experimental results show that the PSA can effectively sense dynamic and static pressures with high sensitivity (0.14–0.87 kPa−1 over a pressure range of 7.2 Pa–2000 kPa), a wide sensing range (0–15000 kPa), fast response time (80 ms), 10,000 cycles (2000 kPa) stability and maintains a 81.25% current response. The noval fully woven structural flexible PSA exhibited larger area, of which the weave density is varied to control resolution and the pressure mapping is referenced to each pixel point to qualitatively and quantitatively analyze shape and pressure distribution. Variable density points pressure sensor with wide sensing range and spatial pressure mappinghas promising applications in healthcare.
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