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1.
Ecotoxicol Environ Saf ; 187: 109828, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31639644

RESUMO

Different forms of aluminum (Al) in soil can be toxic to plants and the bacterial community. In our previous study, the distribution and toxicity to plants of soil Al species and soil labile Al fractions were examined. However, the toxicity of different forms of Al on the bacterial community has not been completely studied. In this study, five soil samples (pH: 4.92, 6.17, 6.62, 6.70, 8.51) were collected from Lichuan, China. Tall fescue was planted in rhizosphere boxes with those soils for 120 days. The toxicity of soil Al species and soil labile Al fractions on the bacterial community of near-rhizosphere (NR) soils and far-rhizosphere (FR) soils were analyzed. The effect of different forms of Al on bacterial community between NR and FR soils was small, but the difference was obvious according to the different spatial distribution of samples. An individual bacterial community has eosinophilia, and most bacterial communities are tolerant of heavy metals (e.g., Cu, Zn, Cd). The toxicity of exchangeable Al has a strong effect on the bacterial community. Meanwhile, the toxicity of Al3+ to the bacterial community is strong. In this study, the key finding was that the toxicity of the Al-F- complex toward the bacterial community and plants was different. AlF2+, AlF2+, AlF3, and AlF4- are toxic for the bacterial community, and the correlation decreases with the addition of F-. This finding is of considerable significance to the treatment of acid-contaminated soil and the study of the tolerance mechanism of plants toward Al.

2.
J Phys Condens Matter ; 32(5): 055302, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31600739

RESUMO

Herein, thermoelectric properties of MoS2/MoSe2 lateral and van der Waals heterostructure are investigated by using density functional theory calculations and non-equilibrium Green's function method. Compared with pure MoS2, the thermoelectric performance of MoS2/MoSe2 lateral heterostructure is significantly improved due to the sharply decreased thermal conductance and slightly reduced power factor. Moreover, the thermoelectric performance can be further improved by constructing MoS2/MoSe2 van der Waals heterostructure. The room temperature ZT can reach 3.5, which is about 3 and 6 times greater than MoS2/MoSe2 lateral heterostructure and pure MoS2, respectively. This is because the strongly local electron and phonon states result in an ultralow thermal conductance in MoS2/MoSe2 van der Waals heterostructure. Furthermore, we also find that the thermoelectric performance of MoS2/MoSe2 van der Waals heterostructure is insensitive to contact areas due to the competing influence of PF and total thermal conductance. The current study presents an effective strategy to improve the thermoelectric performance of 2D heterostructures, which can be extended to a variety of materials for different applications.

3.
J Cell Physiol ; 235(2): 1235-1246, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31267540

RESUMO

Prostate cancer (PCa) is the second leading cause of death among American men. Increasing evidence has shown that long noncoding RNAs (lncRNAs) play important roles in tumorigenesis of PCa. In this study, we explored the biological functions of small nucleolar RNA host gene 12 (SNHG12) and investigated the interaction between miR-133b and SNHG12 in the progression of PCa. Data was downloaded from The Cancer Genome Atlas and Human Cancer Metastasis Database, and clinicopathological characteristics were analyzed with relapse-free survival rate. We detected SNHG12 expression level in PCa cells and tissues, and then analyzed its clinical significance, which revealed that SNHG12 has the potent to predict prognosis of PCa. Bioinformatic analysis revealed that SNHG12 was closely related to the progression of PCa and could target candidate microRNA (miR-133b). After transfecting SNHG12 silencing plasmid and miR-133b mimic/sponge, biological function assays were conducted and results illustrated that SNHG12 associated with miR-133b exerted biological effects on cancer cell growth, migration, and invasion. Direct interactions between miR-133b and SNHG12 have been found and SNHG12 acts as an oncogene to promote tumorigenesis of PCa by sponging tumor suppressor gene miR-133b.

4.
Gen Comp Endocrinol ; : 113347, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31794730

RESUMO

Many marine invertebrate larvae undergo a dramatic morphological and physiological transition from a planktonic larva to a benthic juvenile. The mechanisms of this metamorphosis in bivalves are mainly unknown. The recent identification in bivalves of a thyroid hormone receptor (TR) gene raises the possibility that as occurs in vertebrate metamorphosis, TRs regulate this developmental process. An evolutionary study of TR receptors revealed they are ubiquitous in the molluscs. Knock-down of the TR gene in pediveliger larvae of the hard-shelled mussel, Mytilus coruscus (Mc), using electroporation of siRNA significantly (p < 0.01) reduced TR gene expression. TR gene knock-down decreased pediveliger larval metamorphosis by 54% and was associated with a significant (p < 0.01) reduction in viability compared to control larvae. The TR in the hard-shelled mussel appears to be an essential regulatory factor for the successful epinephrine-induced metamorphosis of the pediveliger larvae to post-larvae. It is hypothesised that the knock-down of TR by siRNA transfection affects the "competence" of pediveliger larvae for the metamorphic transition by reducing their ability to respond to the inducer. The involvement of TR in the epinephrine-induced metamorphosis of a mollusc, the hard-shelled mussel, suggests the role of TR in this process probably emerged early during evolution.

5.
Clin Cancer Res ; 2019 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-31796514

RESUMO

PURPOSE: Emerging evidence indicates that castration-resistant prostate cancer (CRPC) is often driven by constitutively active androgen receptor (AR) or its V7 splice variant (AR-V7) and commonly becomes resistant to endocrine therapy. The aim of this work is to evaluate the function of a kinesin protein, KIF4A, in regulating AR/AR-V7 in prostate cancer endocrine therapy resistance. EXPERIMENTAL DESIGN: We examined KIF4A expression in clinical prostate cancer specimens by immunohistochemistry. Regulated pathways were investigated by qRT-PCR, immunoblot analysis, immunoprecipitation, and luciferase reporter and chromatin immunoprecipitation (ChIP) assays. A series of functional analyses were conducted in cell lines and xenograft models. RESULTS: Examination of the KIF4A protein and mRNA levels in prostate cancer patients showed that increased expression of KIF4A was positively correlated with AR levels. Patients with lower tumor KIF4A expression had improved overall survival (OS) and disease-free survival (DFS). Mechanistically, KIF4A and AR form an auto-regulatory positive feedback loop in prostate cancer: KIF4A binds AR and AR-V7 and prevents CHIP-mediated AR and AR-V7 degradation; AR binds the promoter region of KIF4A and activates its transcription. KIF4A promotes castration-sensitive and castration-resistant prostate cancer cell growth through AR- and AR-V7-dependent signaling. Furthermore, KIF4A expression is upregulated in enzalutamide (ENZ)-resistant prostate cancer cells, and KIF4A knockdown effectively reverses ENZ resistance and enhances the sensitivity of CRPC cells to endocrine therapy. CONCLUSION: These findings indicate that KIF4A plays an important role in the progression of CRPC and serves as a crucial determinant of the resistance of CRPC to endocrine therapy.

6.
Artigo em Inglês | MEDLINE | ID: mdl-31796650

RESUMO

The diversity of thermal transport properties in carbon nanomaterials enables them to be used in different thermal fields such as heat dissipation, thermal management, and thermoelectric conversion. In the past two decades, much effort has been devoted to study the thermal conductivities of different carbon nanomaterials. In this review, different theoretical methods and experimental techniques for investigating thermal transport in nanosystems are first summarized. Then, the thermal transport properties of various pure carbon nanomaterials including 1D carbon nanotubes, 2D graphene, 3D carbon foam, are reviewed in details and the associated underlying physical mechanisms are presented. Meanwhile, we discuss several important influences on the thermal conductivities of carbon nanomaterials, including size, structural defects, chemisorption and strain. Moreover, we introduce different nanostructuring pathways to manipulate the thermal conductivities of carbon-based nanocomposites and focus on the wave nature of phonons for controlling thermal transport. At last, we briefly review the potential applications of carbon nanomaterials in the fields of thermal devices and thermoelectric conversion.

7.
Langmuir ; 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31789036

RESUMO

Gold-silver(Au@Ag)core-shell nanostructures have stronger surface plasma response, wider absorption and scattering in UV-Vis-NIR region and distictive optical properties, which are widely explored in biosensors, information processing, photothermal therapy, and catalysis. Core-shell nanostructures are usually formed by the deposition of the second metal atoms onto the first core metal particles via chemical wet method. The conventional approaches for the manipulation of the shape usually were done by homogeneous growth or etching of isotropic nanoparticles. Through in situ modification of the first metal core at the different locations, different growth model of the second metal can be regulated to control the shapes of core-shell structures. Herein, We modified the gold nanorods (AuNRs) asymmetrically at the end and side parts using thiolated molecules to regulate the morphology of gold nanorod@silver (AuNR@Ag) core-shell nanoparticles. Interestingly, the obvious eccentric nanostructures of AuNR@Ag core-shell nanoparticles were obtained with the increase of the molecular weight of macromolecules modified at the end of AuNRs. So the growth mode was adjusted from Frank-van der Merwe (F-W) mode to Stranski-Krastanow (S-K) mode. By changing the length of the hydrocarbon chain and functional groups of the small mercaptan molecules at the side of AuNRs, the silver-shell exhibit selectively growth at side of the AuNRs, resulting in heterogeneous core-shell nanoparticles and various shapes of AuNR@Ag core-shell. Our method opens up a new avenue towards preparing core-shell nanostructures with the controlled shapes, and the obtained structures are promising in various applications.

8.
Genome Med ; 11(1): 67, 2019 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-31666118

RESUMO

BACKGROUND: Cancer neoantigens are expressed only in cancer cells and presented on the tumor cell surface in complex with major histocompatibility complex (MHC) class I proteins for recognition by cytotoxic T cells. Accurate and rapid identification of neoantigens play a pivotal role in cancer immunotherapy. Although several in silico tools for neoantigen prediction have been presented, limitations of these tools exist. RESULTS: We developed pTuneos, a computational pipeline for prioritizing tumor neoantigens from next-generation sequencing data. We tested the performance of pTuneos on the melanoma cancer vaccine cohort data and tumor-infiltrating lymphocyte (TIL)-recognized neopeptide data. pTuneos is able to predict the MHC presentation and T cell recognition ability of the candidate neoantigens, and the actual immunogenicity of single-nucleotide variant (SNV)-based neopeptides considering their natural processing and presentation, surpassing the existing tools with a comprehensive and quantitative benchmark of their neoantigen prioritization performance and running time. pTuneos was further tested on The Cancer Genome Atlas (TCGA) cohort data as well as the melanoma and non-small cell lung cancer (NSCLC) cohort data undergoing checkpoint blockade immunotherapy. The overall neoantigen immunogenicity score proposed by pTuneos is demonstrated to be a powerful and pan-cancer marker for survival prediction compared to traditional well-established biomarkers. CONCLUSIONS: In summary, pTuneos provides the state-of-the-art one-stop and user-friendly solution for prioritizing SNV-based candidate neoepitopes, which could help to advance research on next-generation cancer immunotherapies and personalized cancer vaccines. pTuneos is available at https://github.com/bm2-lab/pTuneos , with a Docker version for quick deployment at https://cloud.docker.com/u/bm2lab/repository/docker/bm2lab/ptuneos .

9.
Nanotechnology ; 31(8): 085601, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31675748

RESUMO

In general, the preparation of Au nanoparticle clusters (NPCs) is more challenging than that of nanoparticles. The traditional multi-step method for preparing Au NPCs is time consuming and highly sensitive to the reaction conditions. Here, we report a simple and feasible method for the rapid preparation of Au NPCs (∼30 min), in which Au (III) is reduced to Au (0) by trisodium citrate, and assembled into NPCs in the presence of a trace amount of cysteine. The surface plasmon resonance peak of the Au NPCs is tunable and ranged from visible to near-IR regions by varying the content of cysteine added. The growth process of Au NPCs was monitored by dynamic light scattering, UV-vis absorption spectroscopy and transmission electron microscopy. Their elemental composition, chemical state and molecular structure of the sample surface were measured by x-ray photoelectron spectroscopy. The proposed synthesis mechanism has guiding significance for the preparation of other NPCs. Au NPCs used as surface-enhanced Raman spectroscopy substrate has a good enhancement effect because of its unique morphology.

10.
ACS Appl Mater Interfaces ; 11(48): 45256-45264, 2019 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-31710201

RESUMO

Invisible photonic crystal (PC) pattern with encrypted and discoverable information is potentially useful for anti-counterfeiting labels, but it is still a big challenge to realize strict invisibility, fast response, and convenient triggering. Here, a new kind of soaking-revealed invisible PC pattern is fabricated by the regional coating of "ethylene glycol-ethanol" ink on a collapsed inverse opaline macroporous polyurethane (IOM-PU) film, followed by a quick thermal treatment. During the above process, wet heating retains the collapsed but recoverable IOM structure, but dry heating disables the recovery of ordered IOM structure due to the adhesion of macropore walls, which render the "pattern" and the "background" with different optical responses to the solvent. In the dry state, the pattern was invisible because both the collapsed IOM-PU film and the adhesive PU film are colorless and transparent. Once the sample is soaked in ethanol-water mixtures, the invisible pattern appears immediately because only the "wet-heated" region recovers the ordered macroporous structure and shows color, which forms a significant contrast in color to the "dry-heated" region. Compared to the previously invisible PC pattern, the current material has many superior properties, such as high invisibility, large color contrast in showing, excellent recyclability, and good toughness in bending and stretching.

11.
Compr Psychiatry ; 96: 152145, 2019 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-31710880

RESUMO

BACKGROUND: Studies have shown that patients with schizophrenia are at a high risk of developing insulin resistance (IR). We investigated the prevalence of IR and its clinical correlates in hospitalized Chinese patients with schizophrenia. METHODS: A total of 193 patients with schizophrenia (113 males and 80 females) were recruited for the study. We collected their demographic and clinical data, including data on their plasma glucose and lipid levels. All patients were rated using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to assess cognitive function, while Positive and Negative Syndrome Scale (PANSS) was used to assess psychopathology. The cut-off value for the homeostasis model assessment of insulin resistance (HOMA-IR) was set at 1.7. RESULTS: The prevalence of IR was 37.82% (73/193). The IR patients had significantly higher waist-to-hip ratio and body mass index (BMI), and higher fasting plasma glucose (FPG), triglyceride (TG), and low density lipoprotein (LDL) levels compared to non-IR patients (all p<.05). Binary logistic regression analysis showed that smoking, BMI, and TG and LDL levels are significant predictors of IR. In addition, correlation analysis showed that IR was significantly correlated with the waist-to-hip ratio, BMI, and LDL level (Bonferroni corrected p<.05). The multivariable linear regression analysis indicated that the BMI and FPG are associated with the IR index. There was no significant difference in IR index between patients who were taking different antipsychotics. CONCLUSION: We found a high prevalence of IR and its risk factors in Chinese patients with schizophrenia. Active weight control to reduce the BMI and waist circumference and reducing the number of cigarettes consumed, may be essential to decrease the incidence of IR in patients with schizophrenia.

12.
Aging (Albany NY) ; 11(21): 9597-9615, 2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31727869

RESUMO

Kidney cancer ranked in the top 10 for both men and women in the estimated numbers of new cancer cases in the United States in 2018. Targeted therapies have recently been administered to patients with clear cell renal cell carcinoma (ccRCC), but the overall survival of patients at the terminal stage of the disease has not been as good as expected. It is therefore necessary to uncover efficient biomarkers for early diagnosis, and to clarify the molecular mechanisms underlying ccRCC progression and metastasis. Increased evidence has shown that long non-coding RNAs (lncRNAs) play important roles during tumor progression. In this study, 10 candidate lncRNAs with diagnostic and prognostic values in ccRCC were identified: IGFL2-AS1, AC023043.1, AP000439.2, AC124854.1, AL355102.4, TMEM246-AS1, AL133467.3, ZNF582-AS1, LINC01510 and PSMG3-AS1. Enrichment analysis revealed metabolic and functional pathways, which may be closely associated with kidney cancer tumorigenesis. Six representative processes were summarized, namely glycolysis, amino acid metabolism, lipid synthesis, reductive carboxylation, nucleotide metabolism, transmembrane transport and signal transduction. In combination, the present results provided prognostic and diagnostic biomarkers for ccRCC and might pave the way for targeted intervention and molecular therapies in the future.

13.
Neural Netw ; 122: 1-23, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31675624

RESUMO

Human action recognition is one of the most challenging tasks in computer vision. Most of the existing works in human action recognition are limited to single-label classification. A real-world video stream, however, often contains multiple human actions. Such a video stream is usually annotated collectively with a set of relevant human action labels, which leads to a multi-label learning problem. Furthermore, there are a great number of meaningful human actions in reality but it would be extremely difficult, if not impossible, to collect/annotate sufficient video clips regarding all these human actions for training a supervised learning model. In this paper, we formulate a real-world human action recognition task as a multi-label zero-shot learning problem. To address this problem, a joint latent ranking embedding framework is proposed. Our framework holistically tackles the issue of unknown temporal boundaries between different actions within a video clip for multi-label learning and exploits the side information regarding the semantic relationship between different human actions for zero-shot learning. Specifically, our framework consists of two component neural networks for visual and semantic embedding respectively. Thus, multi-label zero-shot recognition is done by measuring relatedness scores of concerned action labels to a test video clip in the joint latent visual and semantic embedding spaces. We evaluate our framework in different settings, including a novel data split scheme designed especially for evaluating multi-label zero-shot learning. The experimental results on two weakly annotated multi-label human action datasets (i.e. Breakfast and Charades) demonstrate the effectiveness of our framework.

14.
J Phys Condens Matter ; 32(10): 105501, 2019 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-31746782

RESUMO

The coexistence of ferroelectricity and topological phase transition in monolayer α-In2Se3 through strain engineering are investigated by first-principles calculation. The results show that with the spontaneous polarization increasing, the transition barrier decreases, approximately linearly related to the applied strain, and the effect of biaxial compressive strain within the in-plane is two orders of magnitude greater than that of tensile strain along the out-of-plane. The results also show that a Dirac cone with a linear dispersion relationship occurs at the high symmetry Γ point within the Brillouin region whatever strain pattern is applied. By analyzing the orbital characters of the electronic states near the Fermi level we find that the electronic structure presents obvious topological phase transition, indicating that monolayer α-In2Se3 is not only an excellent 2D ferroelectric material but also a topological material.

15.
Chem Commun (Camb) ; 55(98): 14757-14760, 2019 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-31754670

RESUMO

A Lewis acid-catalyzed insertion of unsymmetrical alkynes into electron-deficient alkenes was developed for the first time, and used to produce 34 hitherto unreported pentacyclic benzo[5,6]chromeno[2,3-b]indoles with generally good yields and complete stereoselectivity. A Yb(OTf)3-catalyzed reaction between o-alkynylnaphthols and 3-methyleneindolin-2-ones proceeded efficiently, and provided a simple and convergent protocol for alkyne difunctionalization via oxidant-free C-C double bond breaking/rearrangement. Mechanistic details of this domino process were derived by conducting systematic theoretical calculations.

16.
Aging (Albany NY) ; 11(22): 10220-10241, 2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31767812

RESUMO

Circular RNAs (CircRNAs) are a novel subset of non-coding RNA widely present in eukaryotes that play a central role in physiological and pathological conditions. Accumulating evidence has indicated that CircRNAs participated in modulating tumorigenesis by acting as a competing endogenous RNA (CeRNA). However, the roles and functions of CircRNAs in cellular senescence and aging of organisms remain largely obscure. We performed whole transcriptome sequencing to compare the expression patterns of circular RNAs in young and prematurely senescent human diploid fibroblast 2BS cells, and identified senescence-associated circRNAs (SAC-RNAs). Among these SAC-RNAs, we observed the significantly downregulated expression of CircRNAs originating from exons 6 and 7 circularization of the cyclin B1 gene (CCNB1), termed CircCCNB1. Reduced CircCCNB1 expression triggered senescence in young 2BS cells, as measured by increased senescence associated-beta-galactosidase (SA-ß-gal) activity, enhanced expression of cyclin-dependent kinase inhibitor 1A (CDKN1A)/P21 and tumor protein 53 (TP53) expression, and reduced cell proliferation. Mechanistically, reduced CircCCNB1 level inhibited cyclin E2 (CCNE2) expression by modulating micro RNA (miR)-449a activity, which repressed cellular proliferation. Our data suggested that CircCCNB1may serve as a sponge against miR-449a to delay cellular senescence by targeting CCNE2. Targeting CircCCNB1 may represent a promising strategy for aging and age-related disease interventions. Furthermore, we also identified and characterized several kinds of the CircCCNB1-binding proteins (CBPs), which may contribute to the degradation of CircCCNB1.

17.
Exp Brain Res ; 237(12): 3333-3350, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31720812

RESUMO

The mesencephalic locomotor region (MLR) is an essential area for initiation of locomotion. Its functional roles and circuits underlying locomotion have been studied intensively in many species. Studies suggest that cuneiform nucleus and pedunculopontine nucleus (PPN) are two core regions in the MLR for locomotion. However, it remains unclear about cellular components and morphological and intrinsic membrane properties of the neurons in these regions, especially the serotonergic neurons. Using neonatal ePet-EYFP transgenic mice and immunofluorescent technique, we demonstrated existence of 5-HT neurons in the MLR and discovered that 5-HT neurons distributed mainly in the caudal PPN. 5-HT neurons were heterogeneous in MLR and had three types of firing pattern (single spike, phasic and tonic) and two subtypes of morphology (pyramidal and stellate). We measured parameters of 5-HT neurons (n = 35) including resting membrane potential (- 69.2 ± 4.2 mV), input resistance (1410.1 ± 616.9 MΩ), membrane capacitance (36.4 ± 14.9 pF), time constant (49.7 ± 19.4 ms), voltage threshold (- 32.1 ± 7.4 mV), rheobase (21.3 ± 12.4 pA), action potential amplitude (58.9 ± 12.8 mV) and half-width (4.7 ± 1.1 ms), afterhyperpolarization amplitude (23.6 ± 10.4 mV) and half-decay (331.6 ± 157.7 ms). 5-HT neurons were intrinsically different from adjacent non-5-HT neurons and less excitable than them. Hyperpolarization-activated inward currents and persistent inward currents were recorded in 5-HT neurons. NMDA increased excitability of 5-HT neurons, especially the tonic-firing neurons, accompanied with depolarization of membrane potential, hyperpolarization of voltage threshold, reduction of afterhyperpolarization half-decay, and left-shift of frequency-current relationship. This study provided insight into the distribution and properties of 5-HT neurons in the MLR and interaction between serotonergic and glutamatergic modulations.

18.
BMC Neurol ; 19(1): 269, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31684893

RESUMO

BACKGROUND: To determine whether items of the Chinese version of the Montreal Cognitive Assessment Basic (MoCA-BC) could discriminate among cognitively normal controls (NC), and those with mild cognitive impairment (MCI), mild Alzheimer's disease (AD), and moderate-severe (AD), as well as their sensitivity and specificity. METHODS: MCI (n = 456), mild AD (n = 502) and moderate-severe AD (n = 102) patients were recruited from the memory clinic, Huashan Hospital, Shanghai, China. NC (n = 329) were recruited from health checkup outpatients. Five MoCA-BC item scores were collected in interviews. RESULTS: The MoCA-BC orientation test had high sensitivity and specificity for discrimination among MCI, mild AD and moderate-severe AD. The delayed recall memory test had high sensitivity and specificity for MCI screening. The verbal fluency test was efficient for detecting MCI and differentiating AD severity. CONCLUSIONS: Various items of the MoCA-BC can identify MCI patients early and identify the severity of dementia.

19.
J Hazard Mater ; : 121524, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31699479

RESUMO

Tall fescue (Festuca arundinacea Schreb) shows remarkable tolerance to lead (Pb), but the mechanisms involved in metal tolerance are not yet well understood. Here, tall fescue were firstly cultivated hydroponically with Pb2+ (0, 50, 200 and 1000 mg/L) for 14 days. The results showed that remodeling of root architecture plays important roles in tolerance of tall fescue to Pb2+ stress. Increased cell wall (CW) components contribute to restrict high amount of Pb2+ in roots. Additionally, the uronic acid contents of pectin, hemicellulose 1 (HC1) and hemicellulose 2 (HC2) increased under Pb2+ stress. We further observed that tall fescue cultivated with H2O2 showed similar remodeling of root architecture as Pb2+ treatment. Furthermore, pectin, HC1 and HC2 fractions were sequentially extracted from 0 and 10 mM H2O2 treated roots, and Pb2+ adsorption capacity and contents of carboxyl groups of pectin and HC2 fractions were steadily increased under H2O2 treatment in vitro. Our results suggest that degrees of esterification of pectin and HC2 are regulated by H2O2. High amount of low-esterified pectin and HC2 offer more carboxyl groups, provide more Pb2+ binding sites, and restrict more Pb2+ in the CW, which may enhance tolerance of tall fescue to Pb2+ stress.

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