RESUMO
Over the past three decades, there has been a significant global climate change characterized by an increase in the intensity and frequency of extreme climate events. The vegetation status in Qinghai Province has undergone substantial changes, which are more pronounced than other regions in the Qinghai-Tibet Plateau. However, a clear understanding of the response characteristics of plateau vegetation to extreme climate events is currently lacking. In this study, we investigated the response of net primary productivity (NPP) to different forms of extreme climate events across regions characterized by varying levels of aridity and elevation gradients. Specifically, we observed a significant increase in NPP in relatively arid regions. Our findings indicate that, in relatively arid regions, single episodes of high-intensity precipitation have a pronounced positive effect (higher correlation) on NPP. Furthermore, in high-elevation regions (4000-6000 m), both the intensity and frequency of precipitation events are crucial factors for the increase in regional NPP. However, continuous precipitation can have significant negative impacts on certain areas within relatively wet regions. Regarding temperature, a reduction in the number of frost days within a year has been shown to lead to a significant increase in NPP in arid regions. This reduction allows vegetation growth rate to increase in regions where it was limited by low temperatures. Vegetation conditions in drought-poor regions are expected to continue to improve as extreme precipitation intensifies and extreme low-temperature events decrease.
Assuntos
Ecossistema , Modelos Teóricos , China , Tibet , Temperatura , Mudança ClimáticaRESUMO
Solar-induced chlorophyll fluorescence (SIF) has been used since its discovery to characterize vegetation photosynthesis and is an effective tool for monitoring vegetation dynamics. Its response to meteorological drought enhances our comprehension of the ecological consequences and adaptive mechanisms of plants facing water scarcity, informing more efficient resource management and efforts in mitigating climate change. This study investigates the spatial and temporal patterns of SIF and examines how vegetation SIF in the Yellow River Basin (YRB) responds to meteorological drought. The findings reveal a gradual southeast-to-northwest decline in SIF across the Yellow River Basin, with an overall increase-from 0.1083 W m-2µm-1sr-1 in 2001 to 0.1468 W m-2µm-1sr-1 in 2019. Approximately 96% of the YRB manifests an upward SIF trend, with 75% of these areas reaching statistical significance. The Standardized Precipitation Evapotranspiration Index (SPEI) at a time scale of 4 months (The SPEI-4), based on the Liang-Kleeman information flow method, is identified as the most suitable drought index, adeptly characterizing the causal relationship influencing SIF variations. As drought intensified, the SPEI-4 index markedly deviated from the baseline, resulting in a decrease in SIF values to their lowest value; subsequently, as drought lessened, it gravitated towards the baseline, and SIF values began to gradually increase, eventually recovering to near their annual maximum. The key finding is that the variability of SIF with SPEI is relatively pronounced in the early growing season, with forests demonstrating superior resilience compared to grasslands and croplands. The responsiveness of vegetation SIF to SPEI can facilitate the establishment of effective drought early warning systems and promote the rational planning of water resources, thereby mitigating the impacts of climate change.
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Clorofila , Mudança Climática , Secas , Rios , Fluorescência , Luz Solar , FotossínteseRESUMO
Based on Aggregation-Induced Emission (AIE), the development of a label-free, simple and sensitive fluorometric aptasensor for adenosine triphosphate (ATP) detection is described. With ATP present, the aptamers will combine with ATP and the conformation of the aptamer will switch from a random coil to an antiparallel G-quadruplex, which impedes the digestion by exonuclease I (Exo I). Addition of 4,4 -(1E,1E)-2,2-(anthracene-9,10-diyl) bis (ethene-2,1-diyl) bis (N,N, N-trimethyl-benzenaminium iodide) (DSAI) into the solution will cause aggregation of DSAI on the surface of the aptamer/ATP complex and consequently give rise to strong emission. Additionally, a good linear relationship was observed under optimized conditions between the fluorescence intensities and the logarithm of ATP concentrations (R2â¯=â¯0.9908). The established aptamer sensor was highly sensitive and exhibited a low limit of detection of 32.8â¯nM, with superior specificity for ATP. It was also used in the quantification of ATP levels in human serum samples and demonstrated satisfactory recoveries in the scope of 93.2%-107.6%. The cellular ATP assay results indicated that the developed method can be used for monitoring ATP concentrations in cell extracts without the interference of other substances in the cells. This method offers several advantages such as simplicity, rapidity, low cost and excellent selectivity, which make it hold great potential for the detection of ATP in bioanalytical and biological studies.
Assuntos
Trifosfato de Adenosina/análise , Técnicas Biossensoriais/métodos , Fluorometria/métodos , Células A549 , Aptâmeros de Nucleotídeos/química , Fluorescência , Células HeLa , Humanos , Limite de DetecçãoRESUMO
OBJECTIVES: To establish a recombinase flippase (FLP) and flippase recognition target (FRT) system-mediated protocol for post-integration excision of exogenous DNA fragments in the oleaginous yeast Rhodosporidium toruloides. RESULTS: Binary vectors were constructed to harbor FLP expressing cassette together with the hygromycin-resistance marker. Results showed that R. toruloides transformants produced FLP, but failed to mediate removal of the bleomycin-resistance marker within two FRT sites. When FLP was fused with a native nuclear localization signal (NLS) peptide, the system was found functional. Moreover, R. toruloides recombinant strains expressing the NLS-fused FLP under the control of PADH2, an promoter of alcohol dehydrogenase 2 gene (RHTO_03062), were obtained to realize homologous recombination upon growing in glucose-deficient medium. CONCLUSIONS: We have devised a homologous recombination method for R. toruloides based on the FLP/FRT system, which may facilitate further metabolic engineering and designing advanced cell factories for value-added chemicals.
Assuntos
Basidiomycota/genética , DNA Nucleotidiltransferases/genética , Engenharia Genética/métodos , Recombinação Homóloga/genética , Basidiomycota/metabolismo , Biotecnologia , Proteínas Fúngicas/genética , Regiões Promotoras Genéticas/genética , Transformação Genética/genéticaRESUMO
Metabolic engineering of Rhodosporidium toruloides, a robust lipid and caroteinoid producer, is of great importance for oleochemicals and carotenoids production. However, the Agrobacterium-mediated gene transformation is tedious and time consuming. Here, we described a fast and efficient genetic transformation of R. toruloides using electroporation with linear DNA fragments, and the process was optimized. The results showed that 2 × 103 transformants can be obtained at 0.7 kV/µg linear DNA by using hygromycin and bleomycin as selection markers after the competent cells pretreated with 25 mM DTT and 100 mM LiAc. Our results would facilitate mutant library construction and metabolic engineering of R. toruloides for production of oleochemicals and carotenoids. We further demonstrated that all transformants arose due to illegitimate integration of transforming DNA fragments by colony PCR.
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Eletroporação/métodos , Rhodotorula/genética , Transformação Genética , Engenharia Metabólica/métodosRESUMO
OBJECTIVES: To target a carotenoid biosynthetic gene in the oleaginous yeast Rhodosporidium toruloides by using the Agrobacterium-mediated transformation (AMT) method. RESULTS: The RHTO_04602 locus of R. toruloides NP11, previously assigned to code the carotenoid biosynthetic gene CRTI, was amplified from genomic DNA and cloned into the binary plasmid pZPK-mcs, resulting in pZPK-CRT. A HYG-expression cassette was inserted into the CRTI sequence of pZPK-CRT by utilizing the restriction-free clone strategy. The resulted plasmid was used to transform R. toruloides cells according to the AMT method, leading to a few white transformants. Sequencing analysis of those transformants confirmed homologous recombination and insertional inactivation of CRTI. When the white variants were transformed with a CRTI-expression cassette, cells became red and produced carotenoids as did the wild-type strain NP11. CONCLUSIONS: Successful homologous targeting of the CrtI locus confirmed the function of RHTO_04602 in carotenoids biosynthesis in R. toruloides. It provided valuable information for metabolic engineering of this non-model yeast species.
Assuntos
Agrobacterium/genética , Vias Biossintéticas/genética , Carotenoides/biossíntese , Marcação de Genes , Rhodotorula/genética , Rhodotorula/metabolismo , Transformação Genética , Técnicas de Inativação de Genes , Recombinação Homóloga , Análise de Sequência de DNARESUMO
The oleaginous yeast Rhodosporidium toruloides is an unconventional yeast species that can accumulate a high content of lipids. Because it belongs to the basidiomycetous group of fungus, limited tools and functional elements are available for genetic engineering of R. toruloides and related red yeasts. Here we report the functional evaluation of five constitutive promoters from this yeast. We assembled a reporter gene expression cassette, consisting of a promoter, the hygromycin gene (HYG) and the nos terminator, and inserted it into the binary vector pZPK. Hygromycin-resistant transformants were obtained when R. toruloides cells were co-cultured with Agrobacterium tumefaciens AGL1 cells harbouring the engineered vector. Genomic integration of the reporter cassette was verified by successful amplification of target DNA fragments. Quantitative PCR analysis suggested that the transformant had only one copy of the reporter cassette. The strength of these promoters was demonstrated at the phenotypic level on the hygromycin-gradient plate and at the transcriptional level by real-time quantitative PCR. It was found that the strengths of these promoters varied no more than five-fold and followed a decreasing sequence of PPGI, PPGK, PFBA, PTPI, and PGPD. This study established new genetic elements for the construction of superior R. toruloides strains to produce advanced biofuels and related chemicals.
Assuntos
Basidiomycota/genética , Engenharia Genética , Vetores Genéticos/genética , Genoma Fúngico/genética , Regiões Promotoras Genéticas/genética , Basidiomycota/efeitos dos fármacos , Cinamatos/farmacologia , Clonagem Molecular , Higromicina B/análogos & derivados , Higromicina B/farmacologia , Fenótipo , Transformação GenéticaRESUMO
In light of the important antitumor activity of acylhydrazone compounds and based on our previous study, 18 new rotundic acid (RA) acylhydrazone derivatives were synthesized. All of the compounds were characterized by their spectroscopic data. The antiproliferative activity of the compounds was evaluated in vitro via the MTT method in three tumor cell lines, including A-375 (human malignant melanoma cells), SPC-A1 (human lung adenocarcinoma) and NCI-H446 (small cell lung cancer). The results showed that the antiproliferative activity of all of the compounds on the NCI-H446 cell line did not increase compared to RA, however, most of the derivatives exhibited higher activity against the A375 and SPC-A1 cell lines as compared to RA. Importantly, the antiproliferative activities of compounds 5a and 5b were the highest among the compounds, with IC(50) values <10 µM. Collectively, compounds 5a and 5b may act as potential anti-tumor agents in the future.
Assuntos
Adenocarcinoma/tratamento farmacológico , Antineoplásicos , Hidrazonas , Neoplasias Pulmonares/tratamento farmacológico , Melanoma/tratamento farmacológico , Carcinoma de Pequenas Células do Pulmão/tratamento farmacológico , Triterpenos , Adenocarcinoma/metabolismo , Adenocarcinoma/patologia , Antineoplásicos/síntese química , Antineoplásicos/química , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Humanos , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Melanoma/metabolismo , Melanoma/patologia , Carcinoma de Pequenas Células do Pulmão/metabolismo , Carcinoma de Pequenas Células do Pulmão/patologia , Triterpenos/síntese química , Triterpenos/química , Triterpenos/farmacologiaRESUMO
The basidiomycetous yeast Rhodosporidium toruloides represents an excellent producer for microbial lipids and carotenoids. However, further rational engineering of this unconventional yeast remains challenging partially because of the absence of efficient and reliable transformation method. In this study, we developed an Agrobacterium-mediated transformation (ATMT) protocol for effective gene integration into the R. toruloides genome. Both haploid and diploid strains were successfully modified, and the integration was confirmed by colony PCR, Western blot analysis and genome walking. We further demonstrated that multiple genes could be integrated by consecutive ATMT, leading to engineered strains simultaneously resistant to multiple antibiotics. Our results provided a practical method for functional integration and expression of exogenous genes in R. toruloides, which should facilitate the development of genetic tools and the construction of superior strains to produce biofuel molecules and biochemicals.
Assuntos
Basidiomycota/genética , Técnicas de Transferência de Genes , Genética Microbiana/métodos , Genoma Fúngico , Engenharia Metabólica/métodos , Biologia Molecular/métodos , Recombinação Genética , Agrobacterium/genética , Vetores GenéticosRESUMO
STUDY OBJECTIVE: The association between early childhood exposure to general anesthesia and subsequent risk of developing attention-deficit/hyperactivity disorder remains unknown. DESIGN: A systematic review and meta-analysis of cohort studies. PATIENTS: Children undergoing general anesthesia. INTERVENTIONS: A comparison of any type of general anesthesia exposure, including total intravenous anesthesia, inhalation general anesthesia, and combined intravenous and inhaled anesthesia, with non-anesthetic exposures, which did not receive any exposure to anesthetic drugs, including general anesthetics as well as local anesthetics. MEASUREMENTS: The primary outcome measure was the risk of developing attention-deficit/hyperactivity disorder after general anesthesia exposure. MAIN RESULTS: The results of the overall meta-analysis showed an increased risk of subsequent attention-deficit/hyperactivity disorder in children exposed to general anesthesia (RR = 1.26, 95% CI, 1.16-1.38; P < 0.001; I2 = 44.6%). Subgroup analysis found that a single exposure to general anesthesia in childhood was associated with an increased risk of developing attention-deficit/hyperactivity disorder (RR = 1.29, 95% CI, 1.19-1.40, P < 0.001; I2 = 2.6%), and the risk of attention-deficit/hyperactivity disorder was further increased after multiple general anesthesia exposures (RR = 1.61, 95% CI, 1.32-1.97, P < 0.001; I2 = 57.6%). Exposure to general anesthesia lasting 1-60 min during childhood is associated with an increased risk of attention-deficit/hyperactivity disorder (ADHD) (RR: 1.38, 95% CI: 1.26-1.51, P < 0.001; I2 = 0.0%). Moreover, with longer durations of exposure (61-120 min), the risk further rises (RR: 1.55, 95% CI: 1.21-1.99, P = 0.001; I2 = 37.8%). However, no additional increase in ADHD risk was observed with exposures exceeding 120 min (RR: 1.55, 95% CI: 1.35-1.79, P < 0.001; I2 = 0.0%). CONCLUSIONS: Exposure to general anesthesia during early childhood increases the risk of developing attention-deficit/hyperactivity disorder. In particular, multiple general anesthesia exposures and exposures longer than 60 min significantly increase the risk of developing ADHD.
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The Yellow River Basin is short of water resources. The dynamic monitoring of surface water area is helpful to clarify the distribution and change trend of water resources in this area. It is of great scientific significance to deeply understand the impacts of climate change and human activities on water resources and ensure the ecological security of the basin. Based on the Google Earth Engine (GEE) cloud platform, we analyzed the spatial variations of surface water area in the Yellow River Basin from 1986 to 2021 by using the mixed index algorithm, and revealed the driving factors of surface water area change in the Yellow River Basin. The results showed that the overall recognition accuracy of the water extraction algorithm based on mixing index was 97.5%. Compared with available water data products, the proposed algorithm can guarantee the integrity of the whole water area to a certain extent. The surface water area in the upper, middle, and lower reaches of the Yellow River Basin was 71.7%, 18.4%, and 9.9% of the total surface water area, respectively. From 1986 to 2021, the surface water area of the basin showed an overall upward trend, with a total increase of 3163.6 km2. The surface water area of the upper, middle, and downstream regions increased by 72.0%, 22.4%, and 5.6%, respectively. The increase of precipitation was the main reason for the increase of water area, with a contribution of 55%. Vegetation restoration and construction of water conservancy projects had increased the water area of the basin. The intensification of human water extraction activity reduced the water area of the basin.
Assuntos
Monitoramento Ambiental , Água , Humanos , Rios , Mudança Climática , Algoritmos , ChinaRESUMO
Background: Assessment of glomerular lesions and structures plays an essential role in understanding the pathological diagnosis of glomerulonephritis and prognostic evaluation of many kidney diseases. Renal pathophysiological assessment requires novel high-throughput tools to conduct quantitative, unbiased, and reproducible analyses representing a central readout. Deep learning may be an effective tool for glomerulonephritis pathological analysis. Methods: We developed a murine renal pathological system (MRPS) model to objectify the pathological evaluation via the deep learning method on whole-slide image (WSI) segmentation and feature extraction. A convolutional neural network model was used for accurate segmentation of glomeruli and glomerular cells of periodic acid-Schiff-stained kidney tissue from healthy and lupus nephritis mice. To achieve a quantitative evaluation, we subsequently filtered five independent predictors as image biomarkers from all features and developed a formula for the scoring model. Results: Perimeter, shape factor, minimum internal diameter, minimum caliper diameter, and number of objects were identified as independent predictors and were included in the establishment of the MRPS. The MRPS showed a positive correlation with renal score (r = 0.480, p < 0.001) and obtained great diagnostic performance in discriminating different score bands (Obuchowski index, 0.842 [95% confidence interval: 0.759, 0.925]), with an area under the curve of 0.78-0.98, sensitivity of 58-93%, specificity of 72-100%, and accuracy of 74-94%. Conclusion: Our MRPS for quantitative assessment of renal WSIs from MRL/lpr lupus nephritis mice enables accurate histopathological analyses with high reproducibility, which may serve as a useful tool for glomerulonephritis diagnosis and prognosis evaluation.
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The epithelium of the adult prostate contains 3 distinct cell types: basal, luminal, and neuroendocrine. Tissue-regenerative activity has been identified predominantly from the basal cells, isolated by expression of CD49f and stem cell antigen-1 (Sca-1). An important question for the field is whether all basal cells have stem cell characteristics. Prostate-specific microarray databases were interrogated to find candidate surface antigens that could subfractionate the basal cell population. Tumor-associated calcium signal transducer 2 (TACSTD2/Trop2/M1S1/GA733-1) was identified because it was enriched after castration, in prostate sphere cells and in the basal fraction. In the murine prostate, Trop2 shows progenitor characteristics such as localization to the region of the gland proximal to the urethra and enrichment for sphere-forming and colony-forming cells. Trop2 subfractionates the basal cells into 2 populations, both of which express characteristic basal cell markers by quantitative PCR. However, only the basal cells expressing high levels of Trop2 were able to efficiently form spheres in vitro. In the human prostate, where Sca-1 is not expressed, sphere-forming progenitor cells were also isolated based on high expression of Trop2 and CD49f. Trop2-expressing murine basal cells could regenerate prostatic tubules in vivo, whereas the remaining basal cells had minimal activity. Evidence was found for basal, luminal, and neuroendocrine cells in prostatic tubules regenerated from Trop2(hi) basal cells. In summary, functionally distinct populations of cells exist within the prostate basal compartment and an epithelial progenitor can give rise to neuroendocrine cells in vivo.
Assuntos
Células-Tronco Adultas/citologia , Células-Tronco Adultas/metabolismo , Antígenos de Neoplasias/biossíntese , Moléculas de Adesão Celular/biossíntese , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Próstata/citologia , Próstata/metabolismo , Adulto , Animais , Antígenos de Diferenciação/biossíntese , Antígenos Ly/biossíntese , Bases de Dados Genéticas , Regulação da Expressão Gênica/fisiologia , Humanos , Integrina alfa6/biossíntese , Masculino , Proteínas de Membrana/biossíntese , Camundongos , Células Neuroendócrinas/citologia , Células Neuroendócrinas/metabolismo , Uretra/citologia , Uretra/metabolismoRESUMO
The Northeast area of China is a cross region between East Asia and Siberia. Although five populations from this area have been studied in maternal lineage, little is known about the genetics of other populations. In this study, forty-seven Manchu individuals were analyzed using a mitochondrial DNA marker, and fourteen mitochondrial DNA haplogroups, the representative haplogroups of east Eurasian, were identified. All analyses showed that Manchu were close to the neighboring populations such as Mongolian, Korean and northern Han Chinese, and were far from the other populations who lived in the cradle of Manchu, suggesting that the Manchu integrated gradually with natives following its southward migration.
Assuntos
Povo Asiático , DNA Mitocondrial/genética , Proteínas Mitocondriais/genética , Mutação , Povo Asiático/etnologia , Povo Asiático/genética , China , Impressões Digitais de DNA , Emigração e Imigração , Haplótipos , Humanos , Mitocôndrias/genética , Filogeografia , Polimorfismo Genético , Análise de Sequência de DNA , SibériaRESUMO
BACKGROUND: Prostate stem/progenitor cells function in glandular development and maintenance. They may be targets for tumor initiation, so characterization of these cells may have therapeutic implications. Cells from dissociated tissues that form spheres in vitro often represent stem/progenitor cells. A subset of human prostate cells that form prostaspheres were evaluated for self-renewal and tissue regeneration capability in the present study. METHODS: Prostaspheres were generated from 59 prostatectomy specimens. Lineage marker expression and TMPRSS-ERG status was determined via immunohistochemistry and fluorescence in situ hybridization (FISH). Subpopulations of prostate epithelial cells were isolated by cell sorting and interrogated for sphere-forming activity. Tissue regeneration potential was assessed by combining sphere-forming cells with rat urogenital sinus mesenchyme (rUGSM) subcutaneously in immunocompromised mice. RESULTS: Prostate tissue specimens were heterogeneous, containing both benign and malignant (Gleason 3-5) glands. TMPRSS-ERG fusion was found in approximately 70% of cancers examined. Prostaspheres developed from single cells at a variable rate (0.5-4%) and could be serially passaged. A basal phenotype (CD44+CD49f+CK5+p63+CK8-AR-PSA-) was observed among sphere-forming cells. Subpopulations of prostate cells expressing tumor-associated calcium signal transducer 2 (Trop2), CD44, and CD49f preferentially formed spheres. In vivo implantation of sphere-forming cells and rUGSM regenerated tubular structures containing discreet basal and luminal layers. The TMPRSS-ERG fusion was absent in prostaspheres derived from fusion-positive tumor tissue, suggesting a survival/growth advantage of benign prostate epithelial cells. CONCLUSION: Human prostate sphere-forming cells self-renew, have tissue regeneration capability, and represent a subpopulation of basal cells.
Assuntos
Células Epiteliais/fisiologia , Próstata/citologia , Células-Tronco/fisiologia , Antígeno AC133 , Adulto , Idoso , Antígenos CD/análise , Linhagem da Célula , Rearranjo Gênico , Glicoproteínas/análise , Humanos , Receptores de Hialuronatos/análise , Imuno-Histoquímica , Integrina alfa6/análise , Masculino , Pessoa de Meia-Idade , Proteínas de Fusão Oncogênica/análise , Proteínas de Fusão Oncogênica/genética , Peptídeos/análise , Neoplasias da Próstata/patologia , RegeneraçãoRESUMO
A method for the determination of 10 pyrethroid pesticide residues in tea was established by multi-plug filtration cleanup (m-PFC) method combined with gas chromatography-tandem mass spectrometry (GC-MS/MS). Different extraction solvents (acetonitrile, acetone and ethyl acetate) and extraction methods (immersion without water and immersion with water) were compared. The effect of two kinds of QuEChERS pipes and m-PFC column on the purification of tea extracts and the pesticide recoveries were compared. The results showed that the tea samples could be extracted most efficiently when using acetonitrile without immersion in water. The m-PFC column had a good purification effect on the tea extract and could guarantee a high recovery rate. Good linear relationships were observed for the 10 pyrethroid pesticides, and the correlation coefficients (R2) were greater than0.9980. The average recoveries for the 10 pyrethroid pesticides were in the range of 87.5%-111.3% at four spiked levels, and the RSDs were in the range of 2.1%-8.9%. The LODs and LOQs were 0.001-0.015 mg/kg and 0.003-0.05 mg/kg, respectively. The method was applied to the determination of the 10 pyrethroid pesticides in 50 tea samples. The detection rate of the pyrethroid pesticides was 48%, but all the pesticide residues were below the national standard limits. Compared with the traditional QuEChERS and solid phase extraction methods, this method has the advantages of operational simplicity as well as high accuracy and good precision. The establishment of this method provides a new strategy for the rapid detection of pyrethroid pesticide residues in tea.
Assuntos
Contaminação de Alimentos , Resíduos de Praguicidas , Piretrinas , Chá/química , Contaminação de Alimentos/análise , Cromatografia Gasosa-Espectrometria de Massas , Resíduos de Praguicidas/análise , Piretrinas/análise , Extração em Fase Sólida , Espectrometria de Massas em TandemRESUMO
Understanding the changes of runoff, sediment transport, and hydrodynamic parameters of slopes under the influence of landscape patch coverage and connectivity is of great significance for revealing the hydrodynamic mechanism and hydrological connectivity of slope soil erosion process. In this study, the changes of runoff, sediment transport and hydrodynamic parameters of downhill surface in different coverage levels (0%, 20%, 40%, 60%, 90%) and different connectivity modes (vertical path, horizonal path, S-shaped path, random patches) of shrublands were analyzed by field artificial simulated rainfall test. The results showed that, with the increases of shrub cove-rage, runoff yield and sediment yield decreased exponentially. When the coverage increased to more than 60%, the capacity of shrubs to reduce runoff and sediment became stable. With the increases of shrub coverage, flow velocity, flow depth, Reynolds number, Froude number, stream power, and flow shear resistance significantly decreased, while Manning's roughness coefficient and Darcy-Weisbach resistance coefficient increased significantly. When shrub coverage increased to more than 60%, there was no significant difference in the eigenvalues of hydraulic parameters. The runoff rate under the four connectivity modes followed the order of vertical path > S-shaped path > horizonal path > random patches. The sediment rate was the largest in the vertical path, followed by the S-shaped path, and the horizonal path was not significantly different from the random patches. The path with poor connectivity (horizonal path, random patches) exhibited stronger resistance of hydraulic transmission and poor hydraulic sedimentation capacity than the well-connected path (vertical path, S-shaped path). Our results could provide important theoretical basis for soil erosion control on the Loess Plateau and high-quality development of the Yellow River basin.
Assuntos
Monitoramento Ambiental , Sedimentos Geológicos , Rios , SoloRESUMO
Understanding hydrological alteration of rivers and the potential driving factors are crucial for water resources management in the watershed. This study analyzed the daily runoff time series at six gauging stations during 1960-2016 in Wuding River basin, northwestern China. The Mann-Kendall test and Lee-Heghinian method were employed to detect the temporal trends and abrupt changes in annual streamflow. The flow duration curve (FDC) and the index of hydrologic alteration (IHA)/Range of Variability Approach (RVA) were applied to assess the daily streamflow and degree of hydrologic alteration (DHA). In addition, we analyzed the changes of index of hydrological connectivity (IC) and reservoirs/dams (RI) in 1990, 1995, 2000 and 2015 in the basin. The relationship between IC, RI and DHA were assessed to investigate the potential influences of land use changes and constructions of reservoirs/dams on hydrological alteration. The results indicated that annual streamflow at five stations showed significant downward trends (pâ¯<â¯0.01) from 1960 to 2016, and an abrupt changing point appeared in the beginning of 1970s in Wuding River basin. Exception is Qingyangcha station without significant changes, and Hanjiamao station with changing point in 1967. FDC analysis indicated that both high and low flow indices reduced greatly. The integral DHA were higher than 70% at all the stations in the Wuding River basin, suggesting great variation in the magnitude, duration, frequency, timing and rate of change of daily streamflow. Both IC value and RI had close relationship with DHA, implying that DHA was highly affected by land use changes and dams/reservoirs constructions, and was more sensitive to the land use change (pâ¯<â¯0.01). This study provides good insight to understand the effects of soil and water conservation measures on hydrological regime.
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A novel label-free fluorescence aptasensor used for the detection of ochratoxin A (OTA) is presented in this study. When aggregated on the surface of DNA aptamer, aggregation-induced emission (AIE) fluorescence probe presents turn-on fluorescence property. The method proposed in this article was based on an AIE probe, 4, 4-(1E,1E)-2, 2-(anthracene-9, 10-diyl) bis (ethene-2, 1-diyl) bis (N, N, N-trimethylbenzenaminium iodide) (DSAI). With OTA present, the aptamer will combine with OTA and the conformation of the aptamer will switch to an antiparallel G-quadruplex from the initial random coil, which obstructs its digestion by Exo I. After the solution is added with DSAI, DSAI will aggregate on the surface of the aptamer/OTA complex and produces a strong emission. In the range of 5 to 500 ng · ml-1 OTA concentrations, the fluorescence increases with a linear logarithm relationship. The detection limit is 1.9 ng · ml-1. This method was used to detect OTA in spiked real samples, with recoveries and RSDs in the range of 92.2% to 106.3%, and 2.7% to 5.2%, respectively.
Assuntos
Antracenos/química , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais , Corantes Fluorescentes/química , Ocratoxinas/análise , Compostos de Amônio Quaternário/química , Fluorescência , Estrutura Molecular , Espectrometria de FluorescênciaRESUMO
In the present study, the functions and mechanisms of rotundic acid (RA) underlying its induction of apoptosis in caspase-3-transfected MCF-7 human breast cancer cells (Cas3-MCF-7 cells) were investigated. RA induced apoptosis in Cas3-MCF-7 cells more efficiently compared with that in MCF-7 cells transfected with control plasmid. The results from an MTT assay demonstrated that RA effectively inhibited Cas3-MCF-7 cell viability in a dose-dependent manner and induced cell apoptosis via caspase-3 activity within 12 to 48 h. Western blotting and fluorescence-activated cell sorting demonstrated that RA initiated Cas3-MCF-7 cell apoptosis via p53 activation. The silencing of the p53 gene in the Cas3-MCF-7 cell line led to decreased RA-induced Cas3-MCF-7 cell caspase-3 activity and cell apoptosis. Collectively, the results of the present study indicate that caspase-3 serves a critical function in rotundic acid-induced apoptosis, and suggest that caspase-3 deficiency may contribute to the chemotherapy-resistance of breast cancer. Reconstitution of caspase-3 sensitizes MCF-7 breast cancer cells to chemotherapy. RA has the potential for development as a novel drug combined with reconstitution of caspase-3 gene therapy for the treatment of human breast cancer with caspase-3 deficiency.