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1.
Nat Commun ; 11(1): 5073, 2020 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-33033238

RESUMO

Brain cells continuously produce and release protons into the extracellular space, with the rate of acid production corresponding to the levels of neuronal activity and metabolism. Efficient buffering and removal of excess H+ is essential for brain function, not least because all the electrogenic and biochemical machinery of synaptic transmission is highly sensitive to changes in pH. Here, we describe an astroglial mechanism that contributes to the protection of the brain milieu from acidification. In vivo and in vitro experiments conducted in rodent models show that at least one third of all astrocytes release bicarbonate to buffer extracellular H+ loads associated with increases in neuronal activity. The underlying signalling mechanism involves activity-dependent release of ATP triggering bicarbonate secretion by astrocytes via activation of metabotropic P2Y1 receptors, recruitment of phospholipase C, release of Ca2+ from the internal stores, and facilitated outward HCO3- transport by the electrogenic sodium bicarbonate cotransporter 1, NBCe1. These results show that astrocytes maintain local brain extracellular pH homeostasis via a neuronal activity-dependent release of bicarbonate. The data provide evidence of another important metabolic housekeeping function of these glial cells.


Assuntos
Astrócitos/metabolismo , Bicarbonatos/metabolismo , Encéfalo/metabolismo , Espaço Extracelular/metabolismo , Acetazolamida/farmacologia , Trifosfato de Adenosina/metabolismo , Animais , Astrócitos/efeitos dos fármacos , Anidrases Carbônicas/metabolismo , Células Cultivadas , Estimulação Elétrica , Fluorescência , Hipocampo/metabolismo , Concentração de Íons de Hidrogênio , Camundongos Endogâmicos C57BL , Modelos Biológicos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Antagonistas Purinérgicos/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos Sprague-Dawley , Receptores Purinérgicos/metabolismo , Transdução de Sinais , Simportadores de Sódio-Bicarbonato/metabolismo
2.
Water Sci Technol ; 82(6): 1102-1110, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33055400

RESUMO

The cyanobacteria Microcystis flos-aquae can cause harmful algal blooms in waterbodies, which threaten the normal functioning of aquatic ecosystems and human health. Some plant extracts are considered as promising algaecides. In this study, the effects of ten plant extracts (Cinnamomum camphora, Ginkgo biloba, Firmiana platanifolia, Salix babylonica, Euphorbia humifusa, Erigeron annuus, Solidago canadensis, Alternanthera philoxeroides, Thalia dealbata and Eichhornia crassipes) against M. flos-aquae were investigated. The results showed that all ten plant extracts had a significant inhibitory effect on M. flos-aquae growth after 96 h (P < 0.01). The inhibition rates of S. babylonica, E. humifusa, S. canadensis and A. philoxeroides were over 70.00%. Furthermore, the E. humifusa extract had the best inhibitory effect on the photosynthesis of M. flos-aquae, with the effective quantum yield of photosystem II and maximal relative electron transport rate decreasing by 97.50% and 97.00%, respectively, after 96 h. Additionally, the E. humifusa extract was found to be non-toxic to non-target organisms such as Brachydanio rerio and Vallisneria spiralis within 96 h. This study contributes to the existing knowledge and data of freshwater cyanobacteria blooms, and provides insights for their control and the restoration of freshwater systems affected by cyanobacteria blooms.


Assuntos
Microcystis , Ecossistema , Fluorescência , Fotossíntese , Extratos Vegetais
3.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 1556-1559, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018289

RESUMO

Because of the significance of bronchial lesions as indicators of early lung cancer and squamous cell carcinoma, a critical need exists for early detection of bronchial lesions. Autofluorescence bronchoscopy (AFB) is a primary modality used for bronchial lesion detection, as it shows high sensitivity to suspicious lesions. The physician, however, must interactively browse a long video stream to locate lesions, making the search exceedingly tedious and error prone. Unfortunately, limited research has explored the use of automated AFB video analysis for efficient lesion detection. We propose a robust automatic AFB analysis approach that distinguishes informative and uninformative AFB video frames in a video. In addition, for the informative frames, we determine the frames containing potential lesions and delineate candidate lesion regions. Our approach draws upon a combination of computer-based image analysis, machine learning, and deep learning. Thus, the analysis of an AFB video stream becomes more tractable. Using patient AFB video, 99.5%/90.2% of test frames were correctly labeled as informative/uninformative by our method versus 99.2%/47.6% by ResNet. In addition, ≥97% of lesion frames were correctly identified, with false positive and false negative rates ≤3%.Clinical relevance-The method makes AFB-based bronchial lesion analysis more efficient, thereby helping to advance the goal of better early lung cancer detection.


Assuntos
Broncoscopia , Neoplasias Pulmonares , Lesões Pré-Cancerosas , Brônquios , Fluorescência , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Lesões Pré-Cancerosas/diagnóstico por imagem
4.
Anal Chem ; 92(19): 13396-13404, 2020 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-32867467

RESUMO

Rapid, accurate, reliable, and risk-free tracking of pathogenic microorganisms at the single-cell level is critical to achieve efficient source control and prevent outbreaks of microbial infectious diseases. For the first time, we report a promising approach for integrating the concepts of a remarkably large Stokes shift and dual-recognition into a single matrix to develop a pathogenic microorganism stimuli-responsive ratiometric fluorescent nanoprobe with speed, cost efficiency, stability, ultrahigh specificity, and sensitivity. As a proof-of-concept, we selected the Gram-positive bacterium Staphylococcus aureus (S. aureus) as the target analyte model, which easily bound to its recognition aptamer and the broad-spectrum glycopeptide antibiotic vancomycin (Van). To improve the specificity and short sample-to-answer time, we employed classic noncovalent π-π stacking interactions as a driving force to trigger the binding of Van and aptamer dual-functionalized near-infrared (NIR) fluorescent Apt-Van-QDs to the surface of an unreported blue fluorescent π-rich electronic carbon nanoparticles (CNPs), achieving S. aureus stimuli-responsive ratiometric nanoprobe Apt-Van-QDs@CNPs. In the assembly of Apt-Van-QDs@CNPs, the blue CNPs (energy donor) and NIR Apt-Van-QDs (energy acceptor) became close to allow the fluorescence resonance energy transfer (FRET) process, leading to a remarkable blue fluorescence quenching for the CNPs at ∼465 nm and a clear NIR fluorescence enhancement for Apt-Van-QDs at ∼725 nm. In the presence of S. aureus, the FRET process from CNPs to Apt-Van-QDs was disrupted, causing the nanoprobe Apt-Van-QDs@CNPs to display a ratiometric fluorescent response to S. aureus, which exhibited a large Stokes shift of ∼260 nm and rapid sample-to-answer detection time (∼30.0 min). As expected, the nanoprobe Apt-Van-QDs@CNPs showed an ultrahigh specificity for ratiometric fluorescence detection of S. aureus with a good detection limit of 1.0 CFU/mL, allowing the assay at single-cell level. Moreover, we also carried out the precise analysis of S. aureus in actual samples with acceptable results. We believe that this work offers new insight into the rational design of efficient ratiometric nanoprobes for rapid on-site accurate screening of pathogenic microorganisms at the single-cell level in the early stages, especially during the worldwide spread of COVID-19 today.


Assuntos
Bactérias/química , Infecções Bacterianas/diagnóstico , Infecções Bacterianas/microbiologia , Técnicas Biossensoriais/métodos , Corantes Fluorescentes/síntese química , Nanotecnologia/métodos , Antibacterianos/farmacologia , Aptâmeros de Nucleotídeos , Infecções por Coronavirus/complicações , Infecções por Coronavirus/microbiologia , Fluorescência , Transferência Ressonante de Energia de Fluorescência , Microbiologia de Alimentos/métodos , Humanos , Nanopartículas , Pandemias , Pneumonia Viral/complicações , Pneumonia Viral/microbiologia , Sensibilidade e Especificidade , Espectroscopia de Luz Próxima ao Infravermelho , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/química , Vancomicina/farmacologia
5.
Nat Commun ; 11(1): 4772, 2020 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-32973145

RESUMO

Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for vibrational spectroscopy as it provides several orders of magnitude higher sensitivity than inherently weak spontaneous Raman scattering by exciting localized surface plasmon resonance (LSPR) on metal substrates. However, SERS can be unreliable for biomedical use since it sacrifices reproducibility, uniformity, biocompatibility, and durability due to its strong dependence on "hot spots", large photothermal heat generation, and easy oxidization. Here, we demonstrate the design, fabrication, and use of a metal-free (i.e., LSPR-free), topologically tailored nanostructure composed of porous carbon nanowires in an array as a SERS substrate to overcome all these problems. Specifically, it offers not only high signal enhancement (~106) due to its strong broadband charge-transfer resonance, but also extraordinarily high reproducibility due to the absence of hot spots, high durability due to no oxidization, and high compatibility to biomolecules due to its fluorescence quenching capability.


Assuntos
Carbono/química , Nanofios/química , Análise Espectral Raman/métodos , Fluorescência , Porosidade , Reprodutibilidade dos Testes , Ressonância de Plasmônio de Superfície/métodos , Propriedades de Superfície
6.
Ecotoxicol Environ Saf ; 205: 111359, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32961490

RESUMO

As one of the most commonly used and frequently detected herbicides in the coastal seawater, the ecotoxicity of atrazine to phytoplankton has been well demonstrated. However, little attention has been paid to the ecotoxicity of its two major hydrolysates (desisopropylatrazine (DIA) and desethylatrazine (DEA)), which are also widely distributed in natural seawater. Here we present a comprehensive analysis of the photosynthetic physiology and chromophoric dissolved organic matter (CDOM) characteristics of the diatom Phaeodactylum tricornutum Pt-1 (CCMP 2561) under atrazine, DIA and DEA stress, respectively. The results showed that both atrazine and the two derivatives had significant negative effects on the concentration of chlorophyll a, maximum quantum efficiency (Fv/Fm) and relative electron transport rates (rETR) of P. tricornutum Pt-1. Furthermore, the CDOM pattern released by P. tricornutum Pt-1 cells also changed significantly after 7-day exposure. Compared with the control group, the fluorescence intensity (3D-EEM spectra) of protein-like components was obviously lower, while that of the humic acid-like components was higher. The findings of this study indicate that the ecotoxicity of atrazine might have been underestimated in previous investigations: both atrazine and its two major derivatives are not only phototoxic to microalgae but also influence the carbon sequestration potential in the coastal seawater.


Assuntos
Atrazina/toxicidade , Sequestro de Carbono , Diatomáceas/fisiologia , Fotossíntese/efeitos dos fármacos , Clorofila A , Diatomáceas/efeitos dos fármacos , Transporte de Elétrons , Fluorescência , Herbicidas/toxicidade , Microalgas , Fitoplâncton/efeitos dos fármacos , Água do Mar
7.
Biosens Bioelectron ; 169: 112642, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32979593

RESUMO

The outbreaks of the infectious disease COVID-19 caused by SARS-CoV-2 seriously threatened the life of humans. A rapid, reliable and specific detection method was urgently needed. Herein, we reported a contamination-free visual detection method for SARS-CoV-2 with LAMP and CRISPR/Cas12a technology. CRISPR/Cas12a reagents were pre-added on the inner wall of the tube lid. After LAMP reaction, CRISPR/Cas12a reagents were flowed into the tube and mixed with amplicon solution by hand shaking, which can effectively avoid possible amplicon formed aerosol contamination caused by re-opening the lid after amplification. CRISPR/Cas12a can highly specific recognize target sequence and discriminately cleave single strand DNA probes (5'-6FAM 3'-BHQ1). With smart phone and portable 3D printing instrument, the produced fluorescence can be seen by naked eyes without any dedicated instruments, which is promising in the point-of-care detection. The whole amplification and detection process could be completed within 40 min with high sensitivity of 20 copies RNA of SARS-CoV-2. This reaction had high specificity and could avoid cross-reactivity with other common viruses such as influenza virus. For 7 positive and 3 negative respiratory swab samples provided by Zhejiang Provincial Center for Disease Control and Prevention, our detection results had 100% positive agreement and 100% negative agreement, which demonstrated the accuracy and application prospect of this method.


Assuntos
Betacoronavirus/isolamento & purificação , Técnicas Biossensoriais/métodos , Infecções por Coronavirus/diagnóstico , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Amplificação de Ácido Nucleico/métodos , Pneumonia Viral/diagnóstico , Sistemas Automatizados de Assistência Junto ao Leito , Betacoronavirus/genética , Técnicas Biossensoriais/instrumentação , Sistemas CRISPR-Cas , Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Infecções por Coronavirus/virologia , Desenho de Equipamento , Fluorescência , Humanos , Técnicas de Diagnóstico Molecular/instrumentação , Técnicas de Amplificação de Ácido Nucleico/instrumentação , Pandemias , Pneumonia Viral/virologia , Sensibilidade e Especificidade , Smartphone
8.
J Chromatogr A ; 1628: 461440, 2020 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-32822980

RESUMO

A selective and highly sensitive high performance liquid chromatography (HPLC) with fluorescence derivatization method was developed for determination of ethinyl estradiol (EE); one of endocrine-disrupting compounds (EDCs). The fluorescence derivatization procedure was based on Sonogashira coupling reaction using 4-(4, 5-diphenyl-1H-imidazole-2-yl) iodobenzene (DIB-I), a fluorescence labeling reagent, to derivatize EE in presence of copper and palladium ions. The formed fluorescent product was separated on Cosmosil 5C18 MS-II by an isocratic elution with a mobile phase composed of acetonitrile: 5.0 mM Tris-HNO3 buffer, pH 7.4 (60:40, v/v %). The detection wavelengths were set at 310 and 400 nm as excitation and emission wavelengths, respectively. Various parameters affecting derivatization reaction were optimized. Further, the proposed method was validated and a good linearity with low detection limit (S/N=3) 7.4 ng L-1 was obtained in water sample after a simple solid-phase disk extraction (C18 SPE disk) method. The proposed method was successfully applied for detection of EE in river water samples in order to monitor EE concentration and to distinguish its effect on the ecosystem and human health.


Assuntos
Cromatografia Líquida de Alta Pressão , Monitoramento Ambiental/métodos , Etinilestradiol/análise , Rios/química , Espectrometria de Fluorescência , Disruptores Endócrinos/análise , Fluorescência , Extração em Fase Sólida , Poluentes Químicos da Água/análise
9.
Ecotoxicol Environ Saf ; 204: 111136, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32798755

RESUMO

High temperature can lead to increased production of excess light energy, thus reducing photosynthetic capacity in plants. Photosynthetic cyclic electron flow (CEF) in photosystem I (PSI) can effectively protect photosystems, but its physiological mechanism under high temperature is poorly understood. In this study, antimycin A (AA) and thenoyltrifluoroacetone (TTFA) were used to inhibit PGR5-and NDH-dependent CEF pathways, respectively, to reveal the photoprotective functions of CEF for PSII in tobacco leaves under high temperature stress (37 °C, HT). High temperatures caused decreases in maximal photochemistry efficiency (Fv/Fm) and damaged photosystem II (PSII) in tobacco leaves. Under AA inhibition of PGR5-dependent CEF, high temperature increased the fluorescence intensity of point O (Fo) in OJIP curves, i.e., the energy absorption per active reaction center (ABS/RC), the trapping rate of the reaction center (TRo/RC), and the electron transport efficiency per reaction center (ETo/RC) in tobacco leaves. High temperature induced an increase in the hydrogen peroxide content and a decrease in pigment content in tobacco leaves. Under the high temperature treatment, inhibition of PGR5-dependent CEF reduced the activities of the PSII reaction center significantly, destroyed the oxygen-evolving complex (OEC), and impeded photosynthetic electron transfer from PSII to the plastoquinone (PQ) pool in tobacco leaves. The TTFA treatment inhibited the NDH-dependent pathway under high temperature conditions, with the relative fluorescence intensity of point I (VI) decreased significantly, and the content of hydrogen peroxide and superoxide anion increased significantly. Additionally, Fo and the redox degree of the PSII donor side (Wk) increased, and pigment content decreased compared to the control, but with little change compared to high temperature treatment, indicating that the inhibition of the NDH-dependent pathway directly weakened the capacity of the PQ pool to lead to the accumulation of reactive oxygen species (ROS) in tobacco leaves. In conclusion, CEF alleviated damage to the photosynthetic apparatus in tobacco leaves by increasing PSII heat dissipation, reducing ROS production, and maintaining the stability of the PQ pool to accommodate photosynthetic electron flow.


Assuntos
Temperatura Alta , Fotossíntese/fisiologia , Complexo de Proteína do Fotossistema I/metabolismo , Tabaco/metabolismo , Clorofila/metabolismo , Transporte de Elétrons , Elétrons , Fluorescência , Oxirredução , Complexo de Proteína do Fotossistema II/metabolismo , Folhas de Planta/metabolismo , Temperatura , Tabaco/fisiologia
10.
Ecotoxicol Environ Saf ; 204: 111129, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32805505

RESUMO

Anaerobic digestate has been widely used for agricultural activities as an organic fertilizer product. Dissolved organic matter (DOM) derived from anaerobic digestate plays a key role in the speciation, bioavailability and ultimate fate of metals that is related to agriculture and food safety as well as the soil environment. Hence, the binding properties of Cu, Pb and Zn with digestate DOM are investigated using two-dimensional correlation spectroscopy (2D-COS) in combination with ultraviolet absorption, synchronous fluorescence spectra (SFS) and Fourier transform infrared (FTIR) spectroscopy. The 2D absorption COS shows that the DOM at 200 nm is most susceptive with the addition of Pb, followed by Zn and Cu. The log-transformed absorption spectra can also obtain more valuable signals than that from conventional absorption spectra. The 2D-SFS-COS indicates that protein-like peak is more sensitive to the variation of the concentration of metal ions, and fulvic-like substances can preferentially interact with the three heavy metals (HMs). The 2D-FTIR-COS reveals that Cu(II) and Zn(II) ions can be bonded preferentially to the N-H of secondary amide (II), and phenolic OH groups shows a favorable binding with Pb(II). Humic-like peaks with Cu(II) and Zn(II) obtains relatively higher log KM values than fulvic- and protein-like substances. However, the proportion of initial fluorescence (f) for DOM-Cu(II) and DOM-Zn(II) decreased with an increase in wavelength. Protein-like materials have more fluorescent substances that can combine with Cu(II) and Zn(II). This study provides a guide for understanding the geochemical behavior of metal ions in agricultural soils when anaerobic digestate is applied as an organic fertilizer product.


Assuntos
Substâncias Húmicas/análise , Esterco/microbiologia , Metais Pesados/química , Anaerobiose , Animais , Galinhas , Fertilizantes , Fluorescência , Solo/química , Espectrometria de Fluorescência/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
11.
Sensors (Basel) ; 20(17)2020 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-32842601

RESUMO

The global burden of coronavirus disease 2019 (COVID-19) to public health and global economy has stressed the need for rapid and simple diagnostic methods. From this perspective, plasmonic-based biosensing can manage the threat of infectious diseases by providing timely virus monitoring. In recent years, many plasmonics' platforms have embraced the challenge of offering on-site strategies to complement traditional diagnostic methods relying on the polymerase chain reaction (PCR) and enzyme-linked immunosorbent assays (ELISA). This review compiled recent progress on the development of novel plasmonic sensing schemes for the effective control of virus-related diseases. A special focus was set on the utilization of plasmonic nanostructures in combination with other detection formats involving colorimetric, fluorescence, luminescence, or Raman scattering enhancement. The quantification of different viruses (e.g., hepatitis virus, influenza virus, norovirus, dengue virus, Ebola virus, Zika virus) with particular attention to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was reviewed from the perspective of the biomarker and the biological receptor immobilized on the sensor chip. Technological limitations including selectivity, stability, and monitoring in biological matrices were also reviewed for different plasmonic-sensing approaches.


Assuntos
Betacoronavirus/isolamento & purificação , Técnicas Biossensoriais , Infecções por Coronavirus/diagnóstico , Pneumonia Viral/diagnóstico , Ressonância de Plasmônio de Superfície/métodos , Betacoronavirus/patogenicidade , Colorimetria , Infecções por Coronavirus/virologia , Fluorescência , Humanos , Nanoestruturas/química , Pandemias , Pneumonia Viral/virologia , Análise Espectral Raman
12.
Int J Nanomedicine ; 15: 4933-4941, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32764926

RESUMO

Purpose: The aim of this study was to develop an avidin-modified macromolecular lipid magnetic sphere and its application in differential diagnosis of liver disease and liver cancer. Materials and Methods: Lectin-modified macromolecular lipid magnetic spheres were prepared by thin-film hydration method using lentil lectin derivatives (LCA-HQ) and cholesterol as raw materials. Alpha-fetoprotein variants (AFP-L3) in serum from healthy people, liver disease and liver cancer patients were isolated using the prepared lectin-modified macromolecular lipid magnetic spheres, and alpha-fetoprotein (AFP) and AFP-L3 were detected by fully automatic time-resolved fluorescence immunoassay. Results: The lectin polymer lipid magnetic sphere prepared in this study was superparamagnetic and encapsulated by a lectin derivative. There was no significant difference in the recovery rate of AFP-L3 between avidin magnetic ball-automatic time-resolved fluorescence immunoassay and manual micro-affinity column method (p>0.05). We found that AFP-L3 can be used as a differential indicator between liver cancer and liver disease. The positive rate of AFP and AFP-L3 in liver cancer patients was higher than that in healthy people and liver disease patients (p<0.001). The AUC (95% CI) of AFP and AFP-L3 were 0.743 ± 0.031 and 0.850 ± 0.024, respectively. AFP-L3 AUC value is greater than AFP; therefore, AFP-L3 distinguishes liver cancer more accurately, and the difference is statistically different, p<0.05. Conclusion: We proposed a novel method for integration of the lectin polymer lipid magnetic spheres and time-resolved fluorescence immunoassay that enables simple, accurate and rapid determination of AFP-L3 in clinical samples. To be noted, fully automatic time-resolved fluorescence immunoassay compared with the commonly used techniques in clinical practice, the measurement procedure is simple and is expected to be used for the detection and accurate diagnosis of liver cancer.


Assuntos
Fluorescência , Lipossomos/química , Neoplasias Hepáticas/diagnóstico , Mutação , Polímeros/química , alfa-Fetoproteínas/genética , alfa-Fetoproteínas/metabolismo , Adulto , Área Sob a Curva , Automação , Biomarcadores Tumorais/sangue , Feminino , Humanos , Imunoensaio/métodos , Neoplasias Hepáticas/sangue , Imãs/química , Masculino , Pessoa de Meia-Idade , Fatores de Tempo
13.
Int J Esthet Dent ; 15(3): 318-332, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32760926

RESUMO

OBJECTIVE: The fluorescence properties of tooth-colored restorative materials can vary according to the shade of the material. The objective of this study was to investigate the fluorescence behavior of different shades of selected contemporary tooth-colored restorative materials when illuminated with violet light (405 nm wavelength). METHODS: Fifteen different tooth-colored restorative materials, in total 111 shades, were analyzed. Samples of 10-mm diameter and 5-mm thickness were fabricated for each shade. The levels of red, blue, green, and luminosity were analyzed for each sample under 405 nm illumination and an orange long pass filter, using data from the histogram tool in Adobe Photoshop software. RESULTS: There were significant variations in fluorescence luminosity according to both shade and manufacturer. Within any one brand of material, fluorescence emissions differed according to shade, with the lightest shades giving the strongest emissions. Variations in fluorescence were most prominent for composite resins, followed by ormocers, and then glass-ionomer materials. There were also significant variations in fluorescence luminosity between materials of the same shade made by different manufacturers. CONCLUSION: Fluorescence emissions vary considerably among different shades of the same material, and between different materials that are labelled as having the same shade. In the present study, the lightest shades had the greatest emissions under UV light.


Assuntos
Resinas Compostas , Restauração Dentária Permanente , Cor , Materiais Dentários , Fluorescência , Teste de Materiais
14.
Nat Commun ; 11(1): 3847, 2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32737299

RESUMO

Reporter systems are routinely used in plant genetic engineering and functional genomics research. Most such plant reporter systems cause accumulation of foreign proteins. Here, we demonstrate a protein-independent reporter system, 3WJ-4 × Bro, based on a fluorescent RNA aptamer. Via transient expression assays in both Escherichia coli and Nicotiana benthamiana, we show that 3WJ-4 × Bro is suitable for transgene identification and as an mRNA reporter for expression pattern analysis. Following stable transformation in Arabidopsis thaliana, 3WJ-4 × Bro co-segregates and co-expresses with target transcripts and is stably inherited through multiple generations. Further, 3WJ-4 × Bro can be used to visualize virus-mediated RNA delivery in plants. This study demonstrates a protein-independent reporter system that can be used for transgene identification and in vivo dynamic analysis of mRNA.


Assuntos
Aptâmeros de Nucleotídeos/genética , Arabidopsis/genética , Brassica/genética , Engenharia Genética/métodos , RNA Mensageiro/genética , Tabaco/genética , Aptâmeros de Nucleotídeos/química , Aptâmeros de Nucleotídeos/metabolismo , Arabidopsis/metabolismo , Compostos de Benzil/química , Brassica/metabolismo , Fluorescência , Corantes Fluorescentes/química , Regulação da Expressão Gênica , Genes Reporter , Imidazolinas/química , Folhas de Planta/genética , Folhas de Planta/metabolismo , Plantas Geneticamente Modificadas , RNA Mensageiro/metabolismo , Tabaco/metabolismo , Transformação Genética
15.
Artigo em Chinês | MEDLINE | ID: mdl-32842175

RESUMO

Objective:To determine the cell types composing blood-labyrinth barrier in stira vascularis of cochlear lateral wall, analyze the distribution of these composing cells in blood-labyrinth barrier, and to investigate the relationship between perivascular-resident macrophages (PVMs), endothelial cells and pericytes in blood-labyrinth barrier. Method:Cochlear lateral wall tissues were harvested from adult GFP-transgenic mice(C57BL/6). Then the isolated whole stria vascularis tissue was scanned at 0.5 um intervals on the Z axis by two-photon confocal microscope and a 3D-structure of stria vascularis was reconstructed to observe the distribution of capillaries in blood-labyrinth barrier. Cochlear stria vascularis isolated from Balb/c mice was stained by mulit-immunofluorescence and then 3D real time deconvolution of stria vascularis was performed by Imaris software to investigate the distribution of PVMs and pericytes, and their contacting with basement membrane of capillaries was also observed. The ultrastructure of endothelial cells, pericytes and PVMs in blood-labyrinth barrier was observed using transmission electron microscope. Result:The vessels in stria vascularis are parallel to modiolus, distinct from that in spiral ligament which are perpendicular to modiolus. Numerous pericyts in stria vascularis are ensheathed by a vascular basement membrane shared with endothelial cells and closely attaching to the lateral wall of endothelial cells, while PVMs are located outside basement membrane of capillaries. Unlike pericytes that surround one capillary, PVMs branch to connect with more than one capillary. Conclusion:Serial layers on the Z axis scanned by two-photon confocal microscope and a 3D-structure reconstructed by Imaris 3D deconvolution helps to display the micro structure of capillaries in cochlear lateral wall clearly, which could be applied to analyze the 3D structure and function of blood-labyrinth barrier. PVMs in stria vascularis contact with more than one vessel through cytoplasmic processes, suggesting that PVMs may play a more significant role than pericytes in the integrity of blood-labyrinth barrier.


Assuntos
Orelha Interna , Pericitos , Animais , Cóclea , Células Endoteliais , Fluorescência , Camundongos , Camundongos Endogâmicos C57BL , Estria Vascular
16.
Nat Commun ; 11(1): 4316, 2020 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-32859932

RESUMO

Plants utilize a UV-B (280 to 315 nm) photoreceptor UVR8 (UV RESISTANCE LOCUS 8) to sense environmental UV levels and regulate gene expression to avoid harmful UV effects. Uniquely, UVR8 uses intrinsic tryptophan for UV-B perception with a homodimer structure containing 26 structural tryptophan residues. However, besides 8 tryptophans at the dimer interface to form two critical pyramid perception centers, the other 18 tryptophans' functional role is unknown. Here, using ultrafast fluorescence spectroscopy, computational methods and extensive mutations, we find that all 18 tryptophans form light-harvesting networks and funnel their excitation energy to the pyramid centers to enhance light-perception efficiency. We determine the timescales of all elementary tryptophan-to-tryptophan energy-transfer steps in picoseconds to nanoseconds, in excellent agreement with quantum computational calculations, and finally reveal a significant leap in light-perception quantum efficiency from 35% to 73%. This photoreceptor is the first system discovered so far, to be best of our knowledge, using natural amino-acid tryptophans to form networks for both light harvesting and light perception.


Assuntos
Proteínas de Arabidopsis/química , Proteínas de Arabidopsis/metabolismo , Proteínas Cromossômicas não Histona/química , Proteínas Cromossômicas não Histona/metabolismo , Fotorreceptores de Plantas/química , Fotorreceptores de Plantas/metabolismo , Arabidopsis/metabolismo , Arabidopsis/fisiologia , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/genética , Proteínas Cromossômicas não Histona/genética , Transferência de Energia , Fluorescência , Cinética , Luz , Modelos Moleculares , Mutação , Conformação Proteica , Multimerização Proteica , Triptofano/metabolismo , Raios Ultravioleta
19.
Ecotoxicol Environ Saf ; 205: 111173, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32853866

RESUMO

Fulvic acids (FA) are one of the components of humic substances and play an important role in the interaction with metallic species and, consequently, the bioavailability, distribution and toxicity of metals. However, only a few studies have investigated these FA properties in specific environment, such as anthropogenic soils. Therefore, knowledge about FA molecular composition as well as the FA-metal interaction is essential to predict their behavior in the soil. For this reason, the aim of this study was to investigate the molecular composition of FA extracted from two sites in an anthropogenic soil (Terra Mulata), from the Amazon region, as well as their interactions with Cu(II) ions as a model. Results from 13C NMR, infrared and elemental analysis showed that these FA are composed mostly by alkyl structures and oxygen-functional groups, e.g., hydroxyl, carbonyl and carboxyl. The interaction with Cu(II) ions was evaluated by fluorescence quenching, in which the FA showed both high quantity of complexing sites per gram of carbon and good affinity to interact with the metal when compared with other soil FA. The results showed that the complexation capacity was highly correlated by the content of functional groups, while the binding affinity was largely influenced by structural factors. In addition, through the lifetime decay given by time-resolved fluorescence, it was concluded that static quenching took place in FA and Cu(II) interaction with the formation of a non-fluorescent ground-state complex. Therefore, this fraction of soil organic matter will fully participate in complexation reactions, thereby influencing the mobility and bioavailability of metal in soils. Hence, the importance of the study, and the role of FA in the environment, can be seen especially in the Amazon, which is one of the most important biomes in the world.


Assuntos
Benzopiranos/análise , Complexos de Coordenação/análise , Cobre/análise , Substâncias Húmicas/análise , Poluentes do Solo/análise , Solo/química , Benzopiranos/química , Disponibilidade Biológica , Brasil , Carbono/análise , Complexos de Coordenação/química , Cobre/química , Fluorescência , Íons , Modelos Teóricos , Poluentes do Solo/química
20.
Nat Commun ; 11(1): 4032, 2020 08 12.
Artigo em Inglês | MEDLINE | ID: mdl-32788575

RESUMO

Hydrogel-based devices are widely used as flexible electronics, biosensors, soft robots, and intelligent human-machine interfaces. In these applications, high stretchability, low hysteresis, and anti-fatigue fracture are essential but can be rarely met in the same hydrogels simultaneously. Here, we demonstrate a hydrogel design using tandem-repeat proteins as the cross-linkers and random coiled polymers as the percolating network. Such a design allows the polyprotein cross-linkers only to experience considerable forces at the fracture zone and unfold to prevent crack propagation. Thus, we are able to decouple the hysteresis-toughness correlation and create hydrogels of high stretchability (~1100%), low hysteresis (< 5%), and high fracture toughness (~900 J m-2). Moreover, the hydrogels show a high fatigue threshold of ~126 J m-2 and can undergo 5000 load-unload cycles up to 500% strain without noticeable mechanical changes. Our study provides a general route to decouple network elasticity and local mechanical response in synthetic hydrogels.


Assuntos
Reagentes para Ligações Cruzadas/química , Hidrogéis/química , Poliproteínas/química , Estresse Mecânico , Resinas Acrílicas/química , Fluorescência , Fenômenos Mecânicos
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