Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.076
Filtrar
1.
Cell Death Dis ; 11(5): 351, 2020 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-32393761

RESUMO

SETDB1, a histone H3K9 methyltransferase, has been reported to be upregulated in a variety of tumors and promotes cancer development. However, the exact pathogenesis of SETDB1 in human colorectal cancer (CRC) is hitherto unknown. Here, we showed that SETDB1 expression was highly amplified in CRC. Functionally, SETDB1 downregulation in SW480 and HCT116 cells reduced cell proliferation, migration, invasion, and increased CRC cells apoptosis. In contrast, SETDB1 overexpression promoted CRC cells proliferation, migration, and invasion. High expression of SETDB1 was associated with a more aggressive phenotype in vitro. Flow cytometry showed that cell cycle was arrested in G1 phase after SETDB1 silencing. Furthermore, depletion of SETDB1 in vivo suppressed CRC cells proliferation. Mechanistically, p21 was identified as the target of SETDB1. After transfected with siSETDB1, expression of p21 was distinctly increased. In contrast, expression of p21 was significantly decreased after overexpression SETDB1. We also showed that SETDB1 could be involved in the regulation of epithelial-mesenchymal transition (EMT) in HCT116 cells. Moreover, we confirmed that SETDB1 could regulate the activity of p21 promoter by dual-luciferase repoter assay, and proved that SETDB1 could bind to the promoter of p21 and regulate its H3K9me3 enrichment level by ChIP-PCR experiment. Finally, we verified that silencing of SETDB1 inhibited CRC tumorigenesis in vivo. In conclusion, our results indicate that SETDB1 is a major driver of CRC development and might provide a new therapeutic target for the clinical treatment of CRC.

2.
Cell ; 2020 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-32425270

RESUMO

The COVID-19 pandemic urgently needs therapeutic and prophylactic interventions. Here we report the rapid identification of SARS-CoV-2 neutralizing antibodies by high-throughput single-cell RNA and VDJ sequencing of antigen-enriched B cells from 60 convalescent patients. From 8,558 antigen-binding IgG1+ clonotypes, 14 potent neutralizing antibodies were identified with the most potent one, BD-368-2, exhibiting an IC50 of 1.2 ng/mL and 15 ng/mL against pseudotyped and authentic SARS-CoV-2, respectively. BD-368-2 also displayed strong therapeutic and prophylactic efficacy in SARS-CoV-2-infected hACE2-transgenic mice. Additionally, the 3.8Å Cryo-EM structure of a neutralizing antibody in complex with the spike-ectodomain trimer revealed the antibody's epitope overlaps with the ACE2 binding site. Moreover, we demonstrated that SARS-CoV-2 neutralizing antibodies could be directly selected based on similarities of their predicted CDR3H structures to those of SARS-CoV neutralizing antibodies. Altogether, we showed that human neutralizing antibodies could be efficiently discovered by high-throughput single B-cell sequencing in response to pandemic infectious diseases.

3.
Sci Total Environ ; 724: 138187, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32408447

RESUMO

Chlorophenols (CPs) are important pollutants detected frequently in the environment. This study intended to detect the inhibitory effects of fourteen CPs (2-CP, 3-CP, 4-CP, 4C2AP, 4C3MP, 2.4-DCP, 2.3.4-TCP, 2.4.5-TCP, 2.4.6-TCP, 3.4.5-TCP, 2.3.4.5-TECP, 2.3.4.6-TECP, 2.3.5.6-TECP and PCP) towards human liver cytochrome P450 3A4 (CYP3A4). Throughout the tests, testosterone was used as the probe substrate and CPs were used as inhibitors. A series of experiments (enzyme activity assays, preliminary screening tests, inhibition kinetics determination) were conducted to determine the inhibition of CPs towards human liver CYP3A4. CPs with the inhibitory effect >80% were selected for the inhibition evaluation in liver microsomes from different animal species (monkey, rat, dog, pig). The results showed that 2.3.4-TCP, 3.4.5-TCP, and 2.3.4.5-TECP inhibited the activities of CYP3A4 by 80.3%, 93.4%, 91.6%, respectively. Inhibition kinetics type were non-competitive and inhibition kinetics constant (Ki) values were 26.4 µM, 13.5 µM, and 8.8 µM for the inhibition of 2.3.4-TCP, 3.4.5-TCP, and 2.3.4.5-TECP towards human CYP3A4, respectively. Inhibition kinetics type was competitive and Ki value was 4.9 µM for the inhibition of 2.3.4-TCP towards CYP3A4 in Monkey liver microsomes (MyLMs). Inhibition kinetic types were non-competitive and Ki values were 8.1 µM and 28.7 µM for the inhibition of 3.4.5-TCP and 2.3.4.5-TECP towards CYP3A4 in MyLMs. Inhibition kinetic types were non-competitive and Ki values were 13.8 µM, 0.6 µM, and 6.1 µM for the inhibition of 2.3.4-TCP, 3.4.5-TCP, and 2.3.4.5-TECP towards CYP3A4 in Dog liver microsomes (DLMs), respectively. By comparing Ki values and inhibition kinetic types, the dog was the most suitable model to assess the inhibition of 2.3.4-TCP and 2.3.4.5-TECP towards CYP3A4, and monkey was the most suitable model to assess the inhibition of 3.4.5-TCP towards CYP3A4. In conclusion, our recent study on the inhibition of CPs towards CYP3A4 and species differences was important for further toxicological studies of CPs in human bodies.

5.
Mol Pharm ; 2020 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-32356995

RESUMO

Mesothelin is a molecular biomarker of many types of solid cancers, which may represent a highly promising new target in the development of cancer-targeted diagnostic agents. A human anti-mesothelin antibody with a low molecular weight, ET210sc, was applied; this antibody has potent affinity and can penetrate tissue quickly and stably without causing immunoreactions. We developed a new 124/131I-labeled radiotracer of ET210sc. The 124/131I-labeled ET210sc radiotracer showed excellent radiochemical quality (with over 99% radiolabeling yield, 0.07 GBq/µmol specific activity) and remarkable stability in phosphate-buffered saline (>95% at 3 days). The radiotracer retained its potent affinity (dissociation constant, Kd = 0.101 nM). The radiotracer specifically bound to mesothelin-positive cells in vitro. Interestingly, the radiotracer exhibited significant positive-to-negative tumor uptake ratios (1.5:1) 3 days postinjection. The estimated absorbed doses of each organ (e.g., 0.704 mGy/MBq for the rectum; 0.341 mGy/MBq for the spleen) met the medical safety standards for further clinical applications. Our findings provide an initial proof of concept for the potential use of 124/131I-labeled ET210sc radiotracers to detect mesothelin-overexpressing cancer. 124I-ET210sc is proposed to be an ideal imaging agent for further clinical applications.

6.
Artigo em Inglês | MEDLINE | ID: mdl-32338294

RESUMO

Butenoic acid is a short-chain unsaturated fatty acid and important precursor for pharmaceutical and other applications. Heterologous thioesterases are able to convert a fatty acid biosynthesis intermediate in Escherichia coli to butenoic acid. In order to acquire high titer and yield of the product, dynamically switching the metabolic flux from fatty acid biosynthesis pathway to butenoic acid is critical after achieving enough cell mass of the host. A previous developed switch for butenoic acid fermentation is based on triclosan molecule as the FabI inhibitor in the fatty acid biosynthesis cycle. However, triclosan is toxic to human, which may limit its pharmaceutical application. Alternatively, we here purposed a nontoxic switch of carbon flux by harnessing recently developed CRISPR interference (CRISPRi) approach. In our work, we constructed a CRISPRi/dCpf1-mediated dynamic metabolic switch to separate the host growth and production phase via switching the expression of the fabI gene in fatty acid biosynthesis pathway. After optimizing the programmable targets, the CRISPRi-based switch boosted the titer of butenoic acid by 6-fold (1.41 g/L) in fed-batch fermentation. Our work supported that the CRISPRi/dCpf1 switch could replace triclosan-based switch as a nontoxic switch for butenoic acid production, and outcompeted the later switch in the biomass accumulation of the host cell. Moreover, the CRISPRi/dCpf1 system was integrated into the chromosome of the host to improve its genetic stability for long-term fermentation and other applications.Key Points• A programmable metabolic switch was developed to replace the toxic chemical switch to separate the growth phase and production phase of the butenoic acid.• The programmable CRISPRi/dCpf1 switch was efficiently and stably integrated into the host genome to increase their genetic stability during fermentation.• The optimized metabolic switch simultaneously increased the host biomass and butenoic acid titer, and solved the paradox of the competition between growth and production.

7.
Ther Apher Dial ; 2020 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-32306556

RESUMO

The aim of this study was to explore the clinical characteristics and treatment of acquired thrombotic thrombocytopenic purpura (TTP). The clinical manifestations, laboratory findings, differential diagnoses, therapeutic methods, and prognosis of 55 patients with acquired TTP were retrospectively analyzed. Among the 55 TTP patients, 17 were males and 38 were females, with a mean age of 40 ± 15 years. Twenty-one patients had the Triad syndrome, which included neurological syndromes, microangiopathic hemolytic anemia, and thrombocytopenia. Twenty-three patients had the Quinary syndrome, which included fever, microangiopathic hemolytic anemia, thrombocytopenia, renal insufficiency, and neurological symptoms. Twenty-eight patients received the measurement for a disintegrin and metalloprotease with a thrombospondin type 1 motif, member 13 (ADAMTS13) activity and 23 patients had <10% of the normal range. ADAMTS13 inhibitor was tested in 20 patients and was positive in 18 patients. Both ADAMTS13 activity and ADAMTS13 inhibitor were examined in 20 patients and 90% of the patients showed double positive results. The treatment methods included plasma exchange, glucocorticoids, rituximab, immunosuppressants, and intravenous immunoglobulin. Thirty-three patients survived, and 22 patients died. Plasma exchange improved the remission rate from 16.7% to 65.3% (P = .022). The combined immunosuppressive therapy based on plasma exchange and glucocorticoids raised the remission rate from 43.8% to 75.8%. Most of acquired TTP patients had the Triad syndrome or the Quinary syndrome. A high proportion of TTP patients had ADAMTS13 activity reduction and ADAMTS13 inhibitor positivity. Plasma exchange and immunosuppressive therapy may improve the prognosis of this disease.

8.
J Neurochem ; 2020 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-32319677

RESUMO

Gut microbiota, comprising a vast number of microorganism species with complex metagenome, are known to be associated with Alzheimer's disease (AD) and amyloid deposition. However, studies related to gut microbiota have been mostly restricted to comparisons of amyloid deposits, while investigations on neurobehavioral changes and the pathogenesis of AD are limited. Therefore, we aimed to identify the relationship between changes in the intestinal microbiome and the pathogenesis of AD. APPswe /PS1ΔE9 (PAP) transgenic mice and wild-type (WT) mice of different age groups were used. The composition of intestinal bacterial communities in the mice was determined by 16S ribosomal RNA sequencing (16S rRNA Seq), and the Y maze was used to measure cognitive function. Transcriptome sequencing (RNA Seq) and Gene Expression Omnibus (GEO) database (GSE 36980) were used to filter differentially expressed genes (DEGs) between specific pathogen-free (SPF) and germ-free (GF) mice. Quantitative reverse-transcriptase PCR (qRT-PCR) and western blot (WB) were used to verify the results. We found that the intestinal microbiota was significantly different between 5-month-old PAP and WT mice and the cognition of SPF PAP mice was diminished compared to GF PAP and SPF WT mice. DEGs in 5-month-old SPF and GF mice were enriched in the MAPK signalling pathway, and expression of amyloid precursor protein and amyloid deposition increased in 5-month-old SPF PAP mice. Results from this study showed that changes in intestinal microbiota were correlated with impairment of cognitive function and might promote amyloid deposition by stimulating the MAPK signalling pathway in the brain.

9.
Reprod Fertil Dev ; 32(7): 676-689, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32317092

RESUMO

To explore the mechanisms leading to the poor quality of IVF blastocysts, the single-cell whole-genome methylation sequencing technique was used in this study to analyse the methylation patterns of bovine blastocysts derived from invivo, fresh (IVF) or vitrified (V_IVF) oocytes. Genome methylation levels of blastocysts in the IVF and V_IVF groups were significantly lower than those of the invivo group (P<0.05). In all, 1149 differentially methylated regions (DMRs) were identified between the IVF and invivo groups, 1578 DMRs were identified between the V_IVF and invivo groups and 151 DMRs were identified between the V_IVF and IVF groups. For imprinted genes, methylation levels of insulin-like growth factor 2 receptor (IGF2R) and protein phosphatase 1 regulatory subunit 9A (PPP1R9A) were lower in the IVF and V_IVF groups than in the invivo group, and the methylation level of paternally expressed 3 (PEG3) was lower in the V_IVF group than in the IVF and invivo groups. Genes with DMRs between the IVF and invivo and the V_IVF and IVF groups were primarily enriched in oocyte maturation pathways, whereas DMRs between the V_IVF and invivo groups were enriched in fertilisation and vitrification-vulnerable pathways. The results of this study indicate that differences in the methylation of critical DMRs may contribute to the differences in quality between invitro- and invivo-derived embryos.

10.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 28(2): 495-499, 2020 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-32319385

RESUMO

OBJECTIVE: To analyze the incidence, clinical characteristics, treatment efficacy and prognosis of lymphoma patients with mediastinal masses. METHODS: The clinical data of 56 lymphoma patients with mediastinal masses treated in our hospital from February 2007 to January 2018 were collected, and the clinical characteristics, typing, staging, treatment efficacy as well as prognosis analyzed retrospectively. RESULTS: Among the 56 patients, male and female were 25 (45%) cases and 31(55%) cases, respectively. The median age was 31 (17-72) years old, out of them 48 (86%) patients aged below 40 years old. According to pathological classification, 9 (16.1%) cases were diffuse large B cell lymphoma, not otherwise specified (DLBCL-NOS), 26(46.4%) cases were primary mediastinal large B cell lymphoma (PMBCL), 17 (30.4%) cases were classical Hodgkin's lymphoma (cHL), and 4 (7.1%) cases were primary mediastinal grey zone lymphoma (MGZL). All the patients were treated with chemotherapy or immuno-chemotherapy.The median follow-up time was 54.5(11-149) months. In cHL group, 10 cases received involved field radiotherapy (IFRT), 10 (58.8%) cases achieved complete remission (CR), 2 (11.8%) cases achieved partial remisson (PR), and 5 (29.4%) patients experienced progressive disease (PD) , 6 patients with relapsed/refractory disease received autologous hematopoietic stem cell transplantation (auto-HSCT), the 1, 2, and 5 year overall survival (OS) rates of cHL group were 94.1%, 88.2%, and 67.2%, respectively. In MGZL group, 3 cases combined with IFRT, 1 case with auto-HSCT, 2 (50%) cases achieved CR, 2 (50%) cases experienced PD, the 1, 2, 5 year OS rates of MGZL group were 66.7%, 66.7%, and 33.3%, respectively. In PMBCL group, 8 cases combined with IFRT, 7 cases with auto-HSCT, 22 (84.0%) cases achieved CR, 2 (8.0%) cases achieved PR, 1 (4.0%) case was stable disease (SD) and 1 (4.0%) case experienced PD, the 1, 2 year OS rates of PMBCL group were both 100%, and 5 year OS rate was 95.7%. In DLBCL-NOS group, 3 cases combined with IFRT, 2 cases with auto-HSCT, 4 (44.5%) cases achieved CR, 2 (22.2%) cases achieved PR, 1 (11.1%) case was stable disease (SD) and 2 (22.2%) cases experienced PD, the 1 year OS rate of DLBCL-NOS cohort was 100%, 2, and 5 year OS rates were both 77.8%. There was a significant difference of OS rate among these 4 group (P<0.05). In intra-group comparison, OS rate in PMBCL group were significantly longer than both MGZL group (P<0.01) and cHL group(P<0.05), and showed no significant difference from DLBCL-NOS group (P>0.05). CONCLUSION: Mediastinal masses are characterized by unique clinical features due to their unique anatomical location. Several B cell originated lymphomas including cHL,MGZL,PMBCL and DLBCL-NOS, manifested primary or secondary mediastina involvement, tend to occur in young adults and have similar clinical features. However, their therapeutic response was significantly different. The prognosis of PMBCL is prior to MGZL and cHL.

11.
J Nat Prod ; 83(4): 1283-1287, 2020 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-32243144

RESUMO

Dipleosporalones A and B (1 and 2), two new [2 + 2] azaphilone dimers, were obtained from a marine-derived Pleosporales sp. fungus. The absolute configurations of 1 and 2 were elucidated by calculations of their ECD spectra. Dipleosporalone A (1) possessed an unprecedented skeleton with an uncommon 6/4/6 ring system. Compounds 1 and 2 showed cytotoxicity about 30-90-fold more potent than that of their monomer pinophilin B.

12.
Chemosphere ; 254: 126785, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32334250

RESUMO

Fetal overexposure to active glucocorticoid (GC) is the major cause for fetal growth restriction (FGR). This study investigated the influences of cadmium (Cd) exposure on active GC and its mechanism in placental trophoblasts. Pregnant mice were exposed to CdCl2 (4.5 mg/kg, i.p.). Human JEG-3 cells were treated with CdCl2 (0-20 µM). Prenatal Cd exposure significantly increased active GC level in amniotic fluid and placenta. Similarly, Cd treatment also elevated active GC level in medium. Expectedly, the expression of 11ß-HSD2 protein was markedly downregulated in Cd-exposed placental trophoblasts. We further found that Cd activated the PERK/p-eIF2α signaling pathway in placental trophoblasts. Mechanistically, PERK siRNA pretreatment completely blocked PERK/p-eIF2α signaling, and thereby restoring Cd-downregulated 11ß-HSD2 protein expression in human placental trophoblasts. We further found that N-acetylcysteine, a well-known antioxidant, obviously reversed Cd-downregulated 11ß-HSD2 protein expression by inhibiting p-PERK/p-eIF2α signaling in placental trophoblasts. Overall, our data suggest that Cd activates the PERK/p-eIF2α signaling, down-regulates the protein expression of 11ß-HSD2, and thereby elevating active GC level in placental trophoblast.

14.
Artigo em Inglês | MEDLINE | ID: mdl-32337800

RESUMO

Bone marrow (BM) stem cells (BMSCs) are an important source for cell therapy. The outcome of cell therapy could be ultimately associated with the number and function of donor BMSCs. The present study was to evaluate the effect of long-term high-fat diet (HFD) on the population of BMSCs and the role of reactive oxygen species (ROS) in aging mice. Forty-week-old male C57BL/6 mice were fed with HFD for 3 months with regular diet as control. Experiments were repeated when ROS production was reduced in mice treated with N-acetylcysteine (NAC) or using mice overexpressing antioxidant enzyme network (AON) of superoxide dismutase (SOD)1, SOD3, and glutathione peroxidase. BM and blood cells were analyzed with flowcytometry for lineage negative (lin- ) and Sca-1+ , or lin- /CD117+ , or lin- /CD133+ cells. Lin- /CD117+ cell population was significantly decreased with increased intracellular ROS and apoptosis and decreased proliferation in BM, not in blood, in HFD-treated mice without change for Sca-1+ or CD133+ cell populations in BM or blood. NAC treatment or AON overexpression effectively prevented HFD-induced intracellular ROS production and reduction of BM lin- /CD117+ population. These data suggested that long-term HFD selectively decreased BM lin- /CD117+ cell population in aging mice through increased ROS production.

15.
Adv Exp Med Biol ; 1229: 215-229, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32285414

RESUMO

Heart failure (HF) is a leading cause of death worldwide and is still growing. Thus, it's critical to understand the molecular causes of HF and develop effecitive therapies to treat HF. Recently, scientists and clinicians identified that noncoding RNAs play important roles in pathogenesis of HF. Some of noncoding RNAs can serve as novel biomarkers for HF and some of them contribute to the progression of HF. In addition, noncoding RNAs can be related to well-known HF risk factors, such as hypertension, diabetes etc. In this review, we sought to summarize current knowledge about noncoding RNAs and noncoding RNAs mediated regulation of HF and its risk factors.

16.
Adv Exp Med Biol ; 1229: 231-245, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32285415

RESUMO

Cardiovascular disease (CVD) is a common disease which poses a serious threat to human health and it is characterized by high prevalence, high disability and high mortality. Myocardial hypertrophy (MH) is a common pathological process of various cardiovascular diseases and is considered as an independent risk factor for increased cardiovascular morbidity and mortality. Therefore, it is particularly important to understand its pathological mechanism and treatment. In recent years, it has been found that many non-coding RNAs (ncRNAs) play key regulatory roles in humans' various pathophysiological processes. Abnormal expression of ncRNAs in different types of cardiac cells is associated with pathological cardiac hypertrophy. Understanding the relationship between various ncRNAs and intercellular communication through extracellular vesicles (EV) can identify the key ncRNAs which are the accurate targets of precise therapy in this network of action, it also can potentially be a marker for clinical disease diagnosis, which will reflect the progress of the disease earlier and more accurately. There are many factors that regulate the occurrence and development of cardiac hypertrophy, ncRNAs are only a part of them. There are also mutual promotion or inhibition between ncRNAs and other molecules. It will be helpful for us to comprehend the mechanism of cardiac hypertrophy better and provide a sufficient theoretical basis for clinical diagnosis and treatment by defining these relationships.

17.
Artigo em Inglês | MEDLINE | ID: mdl-32269550

RESUMO

11-ketotestosterone (11-KT) is a non-aromatizable and the most potent androgen in a few teleost. It has been reported that 11-KT in serum had a high concentration and increased sharply before the period of yolk deposition in females of few fishes. The aim of this study was to analyze the role of 11-KT both in vivo and in vitro on ovarian development, related gene expression levels, Vitellogenin (Vtg) synthesis, and serum sex steroid concentrations in previtellogenic cultured sterlet (Acipenser ruthenus). Silastic strips embedded with 11-KT (5 or 25 mg/kg) were implanted in vivo for 30 days. Ovarian masculinization or sex reversal was not observed. Histological analysis showed that 11-KT promoted sterlet ovarian development in a dose-dependent manner. Vtg and testosterone (T) increased significantly, while 17ß-estradiol (E2) decreased with no significant difference among groups. The expression of genes androgen receptor (ar), vtg and lipoprotein lipase (lpl) were significantly increased in liver. However, 11-KT had no effect on the expression of foxl2 and cyp19a1 in ovary. In vitro, after incubation with 11-KT (10 and 100 µM) for 5 days, both T and E2 concentrations increased in both hepatic explants and ovarian explants culture medium; the concentration of Vtg also increased in hepatic explants culture medium. The expression of ar, era, vtg, and lpl increased significantly in hepatic explants. However, only the expression of era significantly increased in cultured ovarian explants. Altogether, these results suggest that 11-KT induced ovarian development, as well as Vtg and lipid synthesis, and could be an important factor facilitating the initiation of Vtg synthesis in the liver of the previtellogenic sterlet.

18.
BMC Plant Biol ; 20(1): 139, 2020 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-32245420

RESUMO

BACKGROUND: Response and adaptation strategies of plants to the environment have always been the core issues in ecological research. So far, relatively little study exists on its functional traits responses to warming, especially in an urban environment. This information is the key to help understand plant responses and trade-off strategy to urban warming. RESULTS: We chose the common greening trees of mature age in Beijing (Fraxinus pennsylvanica, Koelreuteria paniculata, and Sophora japonica) as the research subjects, and used infrared heaters to simulate warming for three gradients of natural temperature (CK), moderate warming (T1) and severe warming (T2). Results showed that:(1) Leaf dry matter content (LDMC), chlorophyll content (CHL), leaf tissue density (LTD), and stomatal density (SD) all increased with temperature warming. Specific leaf area (SLA), stomatal size (SS), and stomatal aperture (SA) decreased with simulated warming. (2) SLA was extremely significantly negatively correlated with CHL, LDMC, LTD and SD (P < 0.01), and was extremely significantly positively correlated with SS (P < 0.01). SA was extremely negatively correlated with SD (P < 0.01), and was extremely significantly positively correlated with SS (P < 0.01). There was a significant positive correlation between LDMC and LTD (P < 0.01). This showed that urban greening trees adapted to the environment by coordinating adjustment among leaf functional traits. (3) Under the T1 treatment, the R2 and slope among the leaf traits were higher than CK, and the significance was also enhanced. The correlation between leaf traits was strengthened in this warming environment. Conversely, it will weaken the correlation between leaf traits under the T2 treatment. CONCLUSION: Our study demonstrated that there was a strong trade-off between leaf functional traits in the urban warming environment. Plants in the warming environment have adopted relatively consistent trade-offs and adaptation strategies. Moderate warming was more conducive to strengthening their trade-off potential. It is further verified that the global leaf economics spectrum also exists in urban ecosystems, which is generally tend to a quick-investment return type with the characteristics of thick leaves, strong photosynthetic capacity, low transpiration efficiency and long life in urban environments.

19.
Zhongguo Zhong Yao Za Zhi ; 45(1): 106-112, 2020 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-32237418

RESUMO

To explore the permeation mechanism of micro-molecule medicinal ingredients of water extract of tradition Chinese medicine(TCM) in membrane separation process. With phenolic acid components as the model solute, five phenolic acids with similar molecular weight and structure, namely gallic acid, protocatechuate acid, 4-hydroxybenzoic acid, 3-hydroxybenzoic acid and salicylic acid, were selected in the PES membrane separation experiments. With the relative flux and the transmission rate as indexes, the scanning electron microscopy(SEM) and the electrochemical impedance spectroscopy(EIS) were used to analyze the permeation mechanism of different phenolic acid components. The results showed phenolic acids with similar molecular weight had different permeation behaviors, with decreased relative flux and increased solute permeation with the increase of solute concentration. According to the permeation behavior analyzed by the molecular structure of solute, the transmission rate of phenolic acids increased with the increase of the number of hydroxyl, and the order of substituent positions of phenolic acids based on the permeation rate as follows: para-substituted > meta-substitution > ortho-substitution. Electrochemical impedance spectroscopy reflected the role of charge repulsion in the membrane process; that is to say, the greater the resistance is, the less the solute permeation is. Therefore, the permeation phenomenon of the phenolic acid components in the PES membrane is not only the result of simple sieving mechanisms, but also has the effects of steric hindrance and charge repulsion during the membrane process.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA