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1.
Int J Mach Learn Cybern ; : 1-23, 2021 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-34567279

RESUMO

Emergencies require various emergency departments to collaborate to achieve timely and effective emergency responses. Thus, the overall performance of emergency response is influenced not only by the efficiency of each department alternative but also by the coordination effect among different department alternatives. This paper proposes a collaborative emergency decision making (CEDM) approach considering the synergy among different department alternatives based on the best-worst method (BWM) and TODIM (an acronym in Portuguese of interactive and multiple attribute decision making) method within an interval 2-tuple linguistic environment. First, the evaluation information provided by decision makers (DMs) is represented by interval 2-tuple linguistic variables to reflect and model the underlying diversity and uncertainty. On the basis of the DMs' evaluations, the individual and collaborative performance evaluations of multi-alternative combinations composed of different department alternatives are constructed. Then, the BWM is extended into interval 2-tuple linguistic environment to obtain the weights of evaluation criteria, where the group decision making is taken into account in an interval fuzzy mathematical programming model. Furthermore, to derive more practical and accurate decision results, an interval 2-tuple linguistic TODIM (ITL-TODIM) method is proposed by considering the DMs' psychological behaviours. In the developed ITL-TODIM method, both the gain and loss degrees of one alternative relative to another are simultaneously computed. Finally, a numerical example is presented to illustrate the applicability of the proposed method. Sensitivity and comparative analyses are also provided to demonstrate the effectiveness and advantages of the proposed approach.

2.
Curr Opin Pharmacol ; 60: 291-297, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34507029

RESUMO

Nicotinamide adenine dinucleotide (NAD) is essential for cellular physiological processes, directly or indirectly affecting metabolism and gene expression. The decline of NAD+ levels in the heart is accompanied by aging, causing cardiac pathological remodeling and dysfunction. Niacinamide mononucleotide (NMN) has emerged as a precursor to alleviate age-related cardiac pathophysiological changes by improving cardiac NAD+ homeostasis. Preclinical trials on the efficacy and safety of intaking NMN have shown encouraging results, revealing a cardioprotective effect without significant side effects. Strategies for improving the effectiveness of NMN are also evolving. The present review aimed to summarize the potentials of NMN as a nutraceutical against cardiac aging and highlight the relationship between NMN supplementation and cardiac protection.

3.
Artigo em Inglês | MEDLINE | ID: mdl-34558054

RESUMO

The outbreak of COVID-19 has caused increasing public attention to laboratory-acquired infections (LAIs), especially for a mobile Bio-Safety Level 4 Lab (BSL-4) with high potential of exposure. In this paper, the distribution and removal mechanism of bioaerosols in the biosafety laboratory were studied. A simulation model of airflow distribution in the opening and closing state of air-tight door was established and verified. The results showed that the airflow entrainment velocity during the opening of the door was approximately 0.12 m/s. It increased the probability of vortex generation in the laboratory. The deposition rate of particles was doubled when the air-tight door opening is compared with air-tight door closing. Besides, nearly 80% of the particles deposited on the surface of the wall and ceiling, increasing the possibility of LAIs. The findings of this paper could provide new scientific methods for high-level biosafety laboratories to avoid cross-infection. Moreover, future work regarding air-tight door rotation speed regulation and control should be emphasized.

4.
ACS Appl Mater Interfaces ; 13(33): 38931-38946, 2021 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-34374513

RESUMO

With the continuous development of DNA nanotechnology, various spatial DNA structures and assembly techniques emerge. Hybridization chain reaction (HCR) is a typical example with exciting features and bright prospects in biosensing, which has been intensively investigated in the past decade. In this Spotlight on Applications, we summarize the assembly principles of conventional HCR and some novel forms of linear/nonlinear HCR. With advantages like great assembly kinetics, facile operation, and an enzyme-free and isothermal reaction, these strategies can be integrated with most mainstream reporters (e.g., fluorescence, electrochemistry, and colorimetry) for the ultrasensitive detection of abundant targets. Particularly, we select several representative studies to better illustrate the novel ideas and performances of HCR strategies. Theoretical and practical utilities are confirmed for a range of biosensing applications. In the end, a deep discussion is provided about the challenges and future tasks of this field.


Assuntos
DNA/química , Técnicas Biossensoriais , Colorimetria , Técnicas Eletroquímicas , Humanos , Nanopartículas/química , Técnicas de Amplificação de Ácido Nucleico/métodos , Conformação de Ácido Nucleico , Hibridização de Ácido Nucleico/métodos , Sensibilidade e Especificidade , Espectrometria de Fluorescência
5.
Biol Pharm Bull ; 44(7): 958-966, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34193691

RESUMO

Propofol is a commonly used anesthetic drug in clinic. In recent years, a series of non-anesthetic effects of propofol have been discovered. Studies have shown that propofol has many effects on the intestine. Epidermal growth factor (EGF) is one of the most important growth factors that could regulate intestinal growth and development. In the current study, we studied the effect of protocol on the biological activity of EGF on intestinal tissue and cell models. Through flow cytometry, indirect immunofluorescence and Western-blot and other technologies, it was found that propofol reduced the activity of EGF on intestinal cells, which inhibited EGF-induced intestinal cell proliferation and changed the cell behavior of EGF. To further explore the potential mechanism by which propofol down-regulated epidermal growth factor receptor (EGFR)-induced signaling, we carried out a series of related experiments, and found that propofol may inhibit the proliferation of intestinal cells by inhibiting the EGFR-mediated intracellular signaling pathway. The current research will lay the theoretical and experimental basis for further study of the effect of propofol on the intestine.

6.
Brief Bioinform ; 2021 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-34308480

RESUMO

In single cell analyses, cell types are conventionally identified based on expressions of known marker genes, whose identifications are time-consuming and irreproducible. To solve this issue, many supervised approaches have been developed to identify cell types based on the rapid accumulation of public datasets. However, these approaches are sensitive to batch effects or biological variations since the data distributions are different in cross-platforms or species predictions. In this study, we developed scAdapt, a virtual adversarial domain adaptation network, to transfer cell labels between datasets with batch effects. scAdapt used both the labeled source and unlabeled target data to train an enhanced classifier and aligned the labeled source centroids and pseudo-labeled target centroids to generate a joint embedding. The scAdapt was demonstrated to outperform existing methods for classification in simulated, cross-platforms, cross-species, spatial transcriptomic and COVID-19 immune datasets. Further quantitative evaluations and visualizations for the aligned embeddings confirm the superiority in cell mixing and the ability to preserve discriminative cluster structure present in the original datasets.

7.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 29(3): 881-886, 2021 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-34105488

RESUMO

OBJECTIVE: To explore the influencing factors in children with chronicity immune thrombocytopenia (ITP), and to provide basis for judging the prognosis and treatment in children with ITP. METHODS: The clinical data of children with ITP admitted to The Second Affiliated Hospital of Anhui Medical University in the past 5 years were retrospectively analyzed and followed up for more than 1 year. According to the inclusion criteria, the eligible cases (328 cases in total) were selected and collected through medical record system retrieval, outpatient clinic and telephone follow-up. Independent influencing factors affecting the prognosis of children with ITP were obtained through single-factor and multi-factor logistic analysis, and their predictive value for the prognosis of ITP in children were evaluated. RESULTS: Of 328 children with ITP, 208 were newly diagnosed with ITP (64%), 54 were persistent ITP (16%), 66 were chronic ITP (20%), and the remission rate within 1 year was 79.9%. The results of univariate analysis showed that, age, pre-morbidity history of infection and vaccination, antinuclear antibodies, initial absolute lymphocyte count(ALC) and treatment options were related to the prognosis of the children (P<0.05). Multivariate analysis showed that the history of infection and vaccination before onset, initial treatment options, and ALC at the time of initial diagnosis were independent factors affecting the prognosis of children with ITP (P<0.05). The time for platelet recovery to 100×109/L in the initial treatment group combined with intravenous immunoglobulin (IVIG) was shorter than that in the single corticosteroids group (P<0.01). The receivers operating characteristic (ROC) was drawn with the development of chronic disease (course >12 months) as state variable and ALC or ALC combined with preceding infection or vaccination history as test variable. The results showed that when the absolute value of lymphocytes was 3.80×109/L, the area under the curve was the largest (0.787), the sensitivity was 80.6%, and the specificity was 65.53% (P<0.01), the combined results showed that the maximum area under the curve was 0.859, the sensitivity was 77.61%, and the specificity was 78.41%. CONCLUSION: The initial treatment plan combined with IVIG can reduce the occurrence of chronicity in children with ITP, and its efficacy is better than that of the single corticosteroids group (the platelet recovery time is shorter); history of preceding infection or vaccination, ALC at the time of initial diagnosis are independent factors affecting the prognosis of children with ITP, and the combination of the two shows a better predictive value for the prognosis.


Assuntos
Púrpura Trombocitopênica Idiopática , Trombocitopenia , Criança , Humanos , Imunoglobulinas Intravenosas , Prognóstico , Estudos Retrospectivos
8.
Technol Cancer Res Treat ; 20: 15330338211007253, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33973496

RESUMO

AIM: This study aimed to evaluate the effects of centromere protein W (CENPW, also known as CUG2) in hepatocellular carcinoma (HCC). METHODS: CENPW expression in HCC tissues and cells was detected by RT-qPCR assay. CCK-8 and colony formation assay were used to assess cell proliferation. Wound healing and Transwell assay was used to detect cell migration and invasion, respectively. The flow cytometry was used to analyze the cell cycle distribution and apoptosis. RESULTS: CENPW expression was upregulated in HCC tissues and cells. Knockdown of CENPW inhibited cell proliferation, migration, and invasion and induced the G0/G1 phase arrest and cell apoptosis in HCC cells, which might involve the E2F signaling regulation. CONCLUSION: CENPW acted as an oncogenic role in HCC progression via activation E2F signaling. Our findings may provide new insights into the studying mechanisms of HCC.

9.
Anal Chim Acta ; 1165: 338543, 2021 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-33975698

RESUMO

MicroRNAs (miRNAs) play key regulatory roles in a number of biological processes, which act as critical biomarkers for clinical diagnosis. There are urgent needs to develop advanced tools for accurate and convenient analysis of miRNA in biological circumstances. In this study, an ultrasensitive electrochemical biosensor for miRNA assay is fabricated. Tetrahedral DNA modified gold nanoparticles tags are applied with optimized orientation, which are able to recruit a large number of electrochemical species for remarkable signal responses. Benefiting from the excellent amplification efficiency of the association of strand displacement amplification and catalyzed hairpin assembly, the established method shows ultrahigh sensitivity with the limit of detection as low as 10 aM. A wide linear range from 10-17 to 10-7 M is achieved. In addition, this method is capable to specifically discriminate interfering miRNAs with slightly different sequences. The successful assessment of miRNA levels in human serum samples also demonstrates good practical utility. Therefore, the proposed method has great potential to the applications of miRNA expression profiling and biological studies.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , MicroRNAs , Catálise , DNA/genética , Técnicas Eletroquímicas , Ouro , Humanos , Limite de Detecção , MicroRNAs/genética
10.
Comput Biol Med ; 134: 104481, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33989895

RESUMO

BACKGROUND: Genomic information is nowadays widely used for precise cancer treatments. Since the individual type of omics data only represents a single view that suffers from data noise and bias, multiple types of omics data are required for accurate cancer prognosis prediction. However, it is challenging to effectively integrate multi-omics data due to the large number of redundant variables but relatively small sample size. With the recent progress in deep learning techniques, Autoencoder was used to integrate multi-omics data for extracting representative features. Nevertheless, the generated model is fragile from data noises. Additionally, previous studies usually focused on individual cancer types without making comprehensive tests on pan-cancer. Here, we employed the denoising Autoencoder to get a robust representation of the multi-omics data, and then used the learned representative features to estimate patients' risks. RESULTS: By applying to 15 cancers from The Cancer Genome Atlas (TCGA), our method was shown to improve the C-index values over previous methods by 6.5% on average. Considering the difficulty to obtain multi-omics data in practice, we further used only mRNA data to fit the estimated risks by training XGboost models, and found the models could achieve an average C-index value of 0.627. As a case study, the breast cancer prognosis prediction model was independently tested on three datasets from the Gene Expression Omnibus (GEO), and shown able to significantly separate high-risk patients from low-risk ones (C-index>0.6, p-values<0.05). Based on the risk subgroups divided by our method, we identified nine prognostic markers highly associated with breast cancer, among which seven genes have been proved by literature review. CONCLUSION: Our comprehensive tests indicated that we have constructed an accurate and robust framework to integrate multi-omics data for cancer prognosis prediction. Moreover, it is an effective way to discover cancer prognosis-related genes.


Assuntos
Neoplasias da Mama , Aprendizado Profundo , Neoplasias da Mama/genética , Feminino , Perfilação da Expressão Gênica , Genômica , Humanos , Oncogenes
11.
Pediatr Nephrol ; 36(11): 3585-3593, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33686466

RESUMO

Substance use, a significant public health issue, is well described in the adult chronic kidney disease (CKD) population. Knowledge about substance use in the adolescent and young adult (AYA) CKD population such as prevalence, impact on kidney function, medication adherence, and psychosocial well-being remain largely unknown. Awareness of and inquiring about substance use is paramount to providing evidence-based care and preparation to transition to adult-focused health services. The authors in this review identify commonly used substances (alcohol, tobacco, marijuana, etc.) and how they impact kidney function and care of the AYA with CKD or kidney failure. Recommendations for screening and intervention strategies are provided.

12.
BioData Min ; 13: 10, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32863885

RESUMO

Background: Identifying molecular subtypes of ovarian cancer is important. Compared to identify subtypes using single omics data, the multi-omics data analysis can utilize more information. Autoencoder has been widely used to construct lower dimensional representation for multi-omics feature integration. However, learning in the deep architectures in Autoencoder is difficult for achieving satisfied generalization performance. To solve this problem, we proposed a novel deep learning-based framework to robustly identify ovarian cancer subtypes by using denoising Autoencoder. Results: In proposed method, the composite features of multi-omics data in the Cancer Genome Atlas were produced by denoising Autoencoder, and then the generated low-dimensional features were input into k-means for clustering. At last based on the clustering results, we built the light-weighted classification model with L1-penalized logistic regression method. Furthermore, we applied the differential expression analysis and WGCNA analysis to select target genes related to molecular subtypes. We identified 34 biomarkers and 19 KEGG pathways associated with ovarian cancer. Conclusions: The independent test results in three GEO datasets proved the robustness of our model. The literature reviewing show 19 (56%) biomarkers and 8(42.1%) KEGG pathways identified based on the classification subtypes have been proved to be associated with ovarian cancer. The outcomes indicate that our proposed method is feasible and can provide reliable results.

13.
Gigascience ; 9(7)2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32649756

RESUMO

BACKGROUND: Gene expression plays a key intermediate role in linking molecular features at the DNA level and phenotype. However, owing to various limitations in experiments, the RNA-seq data are missing in many samples while there exist high-quality of DNA methylation data. Because DNA methylation is an important epigenetic modification to regulate gene expression, it can be used to predict RNA-seq data. For this purpose, many methods have been developed. A common limitation of these methods is that they mainly focus on a single cancer dataset and do not fully utilize information from large pan-cancer datasets. RESULTS: Here, we have developed a novel method to impute missing gene expression data from DNA methylation data through a transfer learning-based neural network, namely, TDimpute. In the method, the pan-cancer dataset from The Cancer Genome Atlas (TCGA) was utilized for training a general model, which was then fine-tuned on the specific cancer dataset. By testing on 16 cancer datasets, we found that our method significantly outperforms other state-of-the-art methods in imputation accuracy with a 7-11% improvement under different missing rates. The imputed gene expression was further proved to be useful for downstream analyses, including the identification of both methylation-driving and prognosis-related genes, clustering analysis, and survival analysis on the TCGA dataset. More importantly, our method was indicated to be useful for general purposes by an independent test on the Wilms tumor dataset from the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) project. CONCLUSIONS: TDimpute is an effective method for RNA-seq imputation with limited training samples.

14.
Bioconjug Chem ; 31(3): 764-769, 2020 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-31951119

RESUMO

Herein, a highly sensitive electrochemical genosensor is proposed by the construction of an innovative DNA walking machine. Generally, a number of tetrahedral DNA (TDNA)-supported tracks and walkers are comodified on the electrode surface. DNA walking is inhibited in the absence of target DNA. After the interaction between a DNA walker strand and target DNA, a single-stranded primer sequence could be released, which initiates subsequent rolling circle amplification (RCA). The generated long single-stranded product contains multiple DNAzyme cores, which facilitate highly efficient cleavage of track strands and subsequent DNA walking. The electrode then loses the ability to localize silver nanoparticles (AgNPs) as the electrochemical species. Thus, when the reduced silver stripping current is recorded, a highly sensitive method for the detection of DNA is fabricated. Under optimal conditions, it achieves an admirable sensitivity with the limit of detection as low as 0.1 fM. Satisfactory specificity is also guaranteed. In addition, the practicality is further confirmed by applying human serum samples, which show great potential utility for clinical diagnosis.


Assuntos
Técnicas Biossensoriais/métodos , DNA Catalítico/genética , DNA Catalítico/metabolismo , Limite de Detecção , Técnicas de Amplificação de Ácido Nucleico
15.
Chem Commun (Camb) ; 56(8): 1175-1178, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31919487

RESUMO

We developed a bright carbon nanodot-based miRNA detection method with signal amplification by concatenated hybridization chain reaction (CHCR). In the presence of target miRNA, CHCR was triggered and a frond-like DNA product was formed, which recovered remarkable fluorescence. The location and level of the target miRNA were then indicated.


Assuntos
Carbono/química , MicroRNAs/análise , Pontos Quânticos/química , DNA/química , DNA/genética , Sondas de DNA/química , Sondas de DNA/genética , Humanos , Limite de Detecção , Células MCF-7 , MicroRNAs/genética , Técnicas de Amplificação de Ácido Nucleico/métodos , Hibridização de Ácido Nucleico , Espectrometria de Fluorescência/métodos
16.
J Hazard Mater ; 384: 121297, 2020 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-31586918

RESUMO

The energetic material ammonium nitrate (AN) is used as an industrial raw material; however, it presents a pyrolysis and explosion hazard during transportation and storage, especially when mixed with impurities. To study the effects of typical halides on the thermal decomposition kinetics of AN, a series of precision thermogravimetric analysis experiments at four heating rates were carried out in a nitrogen atmosphere. Based on derivative thermogravimetric analysis, the addition of sodium halides was found to change the kinetic reaction mechanism of AN pyrolysis. The activation energies were obtained using the isoconversional method, and the pre-exponential factor was derived from the kinetic compensation effect. Models of the kinetic reaction mechanism were reliably reconstructed by combining composite kinetic data processing methods, namely, model-free method, model-fitting method, and parameter simulation. A comprehensive analysis showed that the addition of sodium halides shifts the kinetic mechanism of the pyrolysis of AN toward different dominant reaction models (such as reaction order models, power law models, or phase boundary control models) than those of the original reaction model. The results are helpful as a reference and provide guidance for the determination of AN pyrolysis behavior and the simulation of parameters.

17.
Thromb Haemost ; 120(1): 121-131, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31715633

RESUMO

Prethrombotic status (PTS) in patients with stable coronary artery disease (SCAD) increases the risk of coronary thrombosis. Accumulating evidences have indicated that micro-ribonucleic acids (miRNAs) may serve as promising biomarkers for SCAD patients with PTS. The present study aimed to identify the miRNA signature in SCAD patients with PTS and evaluated their diagnostic significance. In the screening phase, 32 differently expressed miRNAs (DEMs) in peripheral blood mononuclear cells (PBMCs) were detected in 35 SCAD patients compared with 5 healthy controls by microarray. MiRNA-gene network analysis was then performed, and 4 DEMs were selected for validation with reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR) test in an independent cohort comprising 79 SCAD patients and 19 healthy controls. Compared with healthy controls, RT-qPCR test verified the upregulations of miR-34a-5p, miR-432-5p, and miR-370-3p detected by microarray; while the upregulation of miR-495-3p measured by RT-qPCR was not consistent with its low expression detected by microarray. Only miR-34a-5p and miR-495-3p were significantly upregulated in the PTS group compared with the non-PTS group (p < 0.01, p < 0.05). Receiver-operating characteristic (ROC) analysis showed that PBMCs-derived miR-34a-5p and miR-495-3p may discriminate PTS with the areas under the ROC curve (AUC) of 0.780 (confidence interval [CI]95% = 0.673-0.866) and 0.712 (CI95% = 0.599-0.808), respectively. The combination of miR-34a-5p and fibrinogen (FIB, a traditional biomarker for PTS) improved AUC to 0.885 (CI95% = 0.793-0.946) and showed added predictive ability compared with FIB, with an integrated discrimination improvement of 0.201 (p < 0.01). Therefore, the combination of miR-34a-5p and FIB may serve as an efficient tool for distinguishing PTS in SCAD patients.


Assuntos
Leucócitos Mononucleares/fisiologia , MicroRNAs/genética , Idoso , Biomarcadores , Estudos de Coortes , Doença da Artéria Coronariana , Feminino , Fibrinogênio/metabolismo , Humanos , Masculino , Análise em Microsséries , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Prognóstico , Risco , Trombose , Transcriptoma
18.
BMC Plant Biol ; 19(1): 575, 2019 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-31864302

RESUMO

BACKGROUND: Low temperature is one of the main environmental factors that limits crop growth, development, and production. Medicago falcata is an important leguminous herb that is widely distributed worldwide. M. falcata is related to alfalfa but is more tolerant to low temperature than alfalfa. Understanding the low temperature tolerance mechanism of M. falcata is important for the genetic improvement of alfalfa. RESULTS: In this study, we explored the transcriptomic changes in the roots of low-temperature-treated M. falcata plants by combining SMRT sequencing and NGS technologies. A total of 115,153 nonredundant sequences were obtained, and 8849 AS events, 73,149 SSRs, and 4189 lncRNAs were predicted. A total of 111,587 genes from SMRT sequencing were annotated, and 11,369 DEGs involved in plant hormone signal transduction, protein processing in endoplasmic reticulum, carbon metabolism, glycolysis/gluconeogenesis, starch and sucrose metabolism, and endocytosis pathways were identified. We characterized 1538 TF genes into 45 TF gene families, and the most abundant TF family was the WRKY family, followed by the ERF, MYB, bHLH and NAC families. A total of 134 genes, including 101 whose expression was upregulated and 33 whose expression was downregulated, were differentially coexpressed at all five temperature points. PB40804, PB75011, PB110405 and PB108808 were found to play crucial roles in the tolerance of M. falcata to low temperature. WGCNA revealed that the MEbrown module was significantly correlated with low-temperature stress in M. falcata. Electrolyte leakage was correlated with most genetic modules and verified that electrolyte leakage can be used as a direct stress marker in physiological assays to indicate cell membrane damage from low-temperature stress. The consistency between the qRT-PCR results and RNA-seq analyses confirmed the validity of the RNA-seq data and the analysis of the regulatory mechanism of low-temperature stress on the basis of the transcriptome. CONCLUSIONS: The full-length transcripts generated in this study provide a full characterization of the transcriptome of M. falcata and may be useful for mining new low-temperature stress-related genes specific to M. falcata. These new findings could facilitate the understanding of the low-temperature-tolerance mechanism of M. falcata.


Assuntos
Aclimatação/genética , Temperatura Baixa , Medicago/fisiologia , Raízes de Plantas/fisiologia , Transcriptoma , Perfilação da Expressão Gênica , Medicago/genética , Raízes de Plantas/genética
19.
Oecologia ; 191(3): 685-696, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31535253

RESUMO

There is limited understanding of the combined effects of discrete climate extremes and chronic environmental changes on ecosystem processes and functioning. We assessed the interactions of extreme drought timing (45 days, in spring or summer) and nitrogen (N) addition in a full factorial field experiment in a Leymus chinensis-dominated meadow steppe in northeast China. We evaluated the resistance and recovery of the grassland (calculated in terms of aboveground biomass) to these two drought events. The spring drought reduced aboveground biomass by 28% in the unfertilized plots and by 33% in the fertilized plots, and the effects persisted during the subsequent post-drought period within the same growing season; however, the summer drought had no significant influence on aboveground biomass. Although there were no significant interactive effects between drought timing and N addition, we observed a potential trend of N addition increasing the proportion of aboveground biomass suppressed by spring drought but not summer drought. Moreover, the drought resistance of the aboveground biomass was positively correlated with the response of the belowground biomass to drought. One year after the extreme drought events, the spring drought effects on aboveground and belowground biomass were negligible. Our results indicate that the drought sensitivity of productivity likely depends on the phenological and morphological traits of the single highly dominant species (Leymus chinensis) in this meadow steppe.


Assuntos
Secas , Ecossistema , Biomassa , China , Pradaria , Poaceae
20.
Anal Chem ; 91(15): 9940-9945, 2019 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-31246440

RESUMO

Herein we describe a novel isothermal and enzyme-free electrochemical aptasensor for protein detection via the employment of polymeric ferrocene nanoparticles (PFcNPs) and target-catalyzed hairpin assembly amplification. The synthesized PFcNPs not only load numerous Fc molecules for enhanced electrochemical output but also possess plenty of amino groups, which increase the water solubility and facilitate the conjugation with the aptamer toward the recognition of target protein. After the formation of an aptamer/protein complex, the conformation of the DNA probe changes, which further triggers hairpin assembly on top of DNA tetrahedral structures modified on the electrode interface. The process can be recycled, and multiple PFcNPs are localized on the electrode. Thus, an amplified electrochemical signal is able to be recorded, which is sufficient to achieve a demonstrated limit of detection as low as 67 fM. This developed aptasensor can also discriminate target protein from other interfering substances with a high selectivity. Furthermore, it has been successfully applied in diluted real blood serum samples. All of these features make the present methodology a promising candidate for ultratrace protein biosensors.


Assuntos
Compostos Ferrosos/química , Metalocenos/química , Nanopartículas/química , Proteínas/análise , Catálise , DNA/química , DNA/metabolismo , Técnicas Eletroquímicas/métodos , Eletrodos , Humanos , Imunoglobulina G/análise , Imunoglobulina G/metabolismo , Limite de Detecção , Ligação Proteica , Proteínas/metabolismo , Trombina/análise , Trombina/metabolismo
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