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1.
Talanta ; 233: 122490, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34215111

RESUMO

In natural environments, Acid Volatile Sulfides (AVS) contained in anoxic waters or sediments, are composed of dissolved sulfides and neo-formed sulfides colloids or particles. Under acidic addition, AVS emit hydrogen sulfide gas and release the so-called simultaneously extracted metals (SEM). The measurement of AVS coupled with that of the SEM enables to evaluate the metal trapping capacity of sulfides in the environment. Because AVS are extremely reactive to oxidation, the most accurate methodology to quantify AVS and SEM requires to be able to process the samples extraction on-site, directly after sampling and avoiding oxygen exposure. However, most of available systems are based on glassware 'purge and trap' techniques developed for the laboratory and are not often adapted to field studies. In these systems, AVS extraction time can range from 30 min to 3 h with relative standard deviation from 7 to 44%. In this study, we developed a new 'purge and trap' system designed for both laboratory use and field AVS/SEM extractions. The system is optimized with a shortened extraction time, miniaturized, unbreakable, easy and reproducible to develop parallel extraction benches. Analytical yields, precision and stability have been improved, allowing to reduce the extraction time to 1 h with an absolute quantification limit of 0.12 µmol S(-II) with a relative standard deviation between 7 and 11% and under a complete extraction efficiency.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Monitoramento Ambiental , Sedimentos Geológicos , Laboratórios , Metais , Metais Pesados/análise , Sulfetos/análise , Volatilização , Poluentes Químicos da Água/análise
2.
Int J Mol Sci ; 22(11)2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-34199627

RESUMO

Investigating metal-ion solvation-in particular, the fundamental binding interactions-enhances the understanding of many processes, including hydrogen production via catalysis at metal centers and metal corrosion. Infrared spectra of the hydrated zinc dimer (Zn2+(H2O)n; n = 1-20) were measured in the O-H stretching region, using infrared multiple photon dissociation (IRMPD) spectroscopy. These spectra were then compared with those calculated by using density functional theory. For all cluster sizes, calculated structures adopting asymmetric solvation to one Zn atom in the dimer were found to lie lower in energy than structures adopting symmetric solvation to both Zn atoms. Combining experiment and theory, the spectra show that water molecules preferentially bind to one Zn atom, adopting water binding motifs similar to the Zn+(H2O)n complexes studied previously. A lower coordination number of 2 was observed for Zn2+(H2O)3, evident from the highly red-shifted band in the hydrogen bonding region. Photodissociation leading to loss of a neutral Zn atom was observed only for n = 3, attributed to a particularly low calculated Zn binding energy for this cluster size.


Assuntos
Metais/química , Modelos Moleculares , Água/química , Zinco/química , Cátions/química , Ligação de Hidrogênio , Fótons
3.
Chimia (Aarau) ; 75(6): 530-534, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-34233819

RESUMO

More than 50% of proteinogenic amino acid sidechains can bind metal ions, enabling proteins and peptides to bear these ions as cofactors. Nevertheless, post-translational modifications and incorporation of noncanonical amino acids bestow peptides and proteins myriads of other coordination capabilities, thanks to an enhanced metal binding. Here we summarize selected examples of natural and artificial systems that contain one or more noncanonical amino acids coordinating a metal ion and subsequently achieve a new or enhanced function. We report on a wide array of systems: from disease-related proteins that undergo sulfurylation or phosphorylation through natural metallophores that selectively capture precious essential ions to synthetic selfassembly strategies, biocatalysts, and chelating agents against toxic metals. Regardless of their (bio)synthetic routes, all possess unique metal-binding properties that could not be effectively achieved by systems composed of canonical residues.


Assuntos
Aminoácidos , Quelantes , Metais , Peptídeos , Proteínas
4.
Int J Mol Sci ; 22(11)2021 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-34072512

RESUMO

Synthetic materials commonly used in the packaging industry generate a considerable amount of waste each year. Chitosan is a promising feedstock for the production of functional biomaterials. From a biological point of view, chitosan is very attractive for food packaging. The purposes of this study were to evaluate the antibacterial activity of a set of chitosan-metal oxide films and different chitosan-modified graphene (oxide) films against two foodborne pathogens: Campylobacter jejuni ATCC 33560 and Listeria monocytogenes 19115. Moreover, we wanted to check whether the incorporation of antimicrobial constituents such as TiO2, ZnO, Fe2O3, Ag, and graphene oxide (GO) into the polymer matrices can improve the antibacterial properties of these nanocomposite films. Finally, this research helps elucidate the interactions of these materials with eukaryotic cells. All chitosan-metal oxide films and chitosan-modified graphene (oxide) films displayed improved antibacterial (C. jejuni ATCC 33560 and L. monocytogenes 19115) properties compared to native chitosan films. The CS-ZnO films had excellent antibacterial activity towards L. monocytogenes (90% growth inhibition). Moreover, graphene-based chitosan films caused high inhibition of both tested strains. Chitosan films with graphene (GO, GOP, GOP-HMDS, rGO, GO-HMDS, rGOP), titanium dioxide (CS-TiO2 20:1a, CS-TiO2 20:1b, CS-TiO2 2:1, CS-TiO2 1:1a, CS-TiO2 1:1b) and zinc oxide (CS-ZnO 20:1a, CS-ZnO 20:1b) may be considered as a safe, non-cytotoxic packaging materials in the future.


Assuntos
Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Materiais Biocompatíveis , Quitosana , Microbiologia de Alimentos , Embalagem de Alimentos , Membranas Artificiais , Antibacterianos/química , Antibacterianos/farmacologia , Membrana Externa Bacteriana/efeitos dos fármacos , Permeabilidade da Membrana Celular/efeitos dos fármacos , Quitosana/química , Metais/química , Polímeros
5.
Medicine (Baltimore) ; 100(25): e26470, 2021 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-34160455

RESUMO

RATIONALE: Intraocular foreign bodies (IOFBs) are common in ocular injuries, but asymptomatic metallic IOFBs retained in the anterior chamber for years are rare. PATIENT CONCERNS: A 31-year-old female presented with blurred vision in her right eye after lumbar magnetic resonance imaging. Her best-corrected vision acuity was 0.6 in the right eye and 1.0 in the left eye. Slit-lamp examination revealed a brown granular foreign body in the anterior chamber and pigmentation of the limbus. Lens and retina examination indicated ocular siderosis. Corneal endothelioscopy revealed decreased endothelial cell density. A detailed history showed ocular globe injury 15 years earlier. DIAGNOSES: Anterior chamber IOFB with ocular siderosis. INTERVENTIONS: Anterior chamber foreign body removal was performed with appropriate incision and forceps. OUTCOMES: The anterior chamber IOFB was successfully removed and examined as a magnetic metal foreign body. The best-corrected vision acuity was 1.0 at 1 day postoperatively. An abnormal electroretinogram with a 12% decrease in the "b" wave and a 91% decrease in the "a" wave was observed 3 months postoperatively. There were no intraoperative or postoperative complications during a 3-month follow-up. LESSONS: Eye trauma should be examined carefully to exclude IOFBs. Asymptomatic anterior chamber foreign bodies can also cause corneal endothelial injury and ocular siderosis. Careful examination and timely management are needed in such cases.


Assuntos
Corpos Estranhos no Olho/diagnóstico , Ferimentos Oculares Penetrantes/complicações , Metais/efeitos adversos , Transtornos da Visão/etiologia , Adulto , Câmara Anterior/diagnóstico por imagem , Câmara Anterior/cirurgia , Doenças Assintomáticas , Corpos Estranhos no Olho/etiologia , Corpos Estranhos no Olho/cirurgia , Feminino , Humanos , Cristalino/diagnóstico por imagem , Imageamento por Ressonância Magnética/efeitos adversos , Microscopia com Lâmpada de Fenda , Tomografia de Coerência Óptica , Resultado do Tratamento , Transtornos da Visão/diagnóstico , Transtornos da Visão/cirurgia , Acuidade Visual
6.
Nat Commun ; 12(1): 3706, 2021 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-34140488

RESUMO

Organometallic complexes are ubiquitous in chemistry and biology. Whereas their preparation has historically relied on ligand synthesis followed by coordination to metal centers, the ability to efficiently diversify their structures remains a synthetic challenge. A promising yet underdeveloped strategy involves the direct manipulation of ligands that are already bound to a metal center, also known as chemistry-on-the-complex. Herein, we introduce a versatile platform for on-the-complex annulation reactions using transient aryne intermediates. In one variant, organometallic complexes undergo transition metal-catalyzed annulations with in situ generated arynes to form up to six new carbon-carbon bonds. In the other variant, an organometallic complex bearing a free aryne is generated and intercepted in cycloaddition reactions to access unique scaffolds. Our studies, centered around privileged polypyridyl metal complexes, provide an effective strategy to annulate organometallic complexes and access complex metal-ligand scaffolds, while furthering the synthetic utility of strained intermediates in chemical synthesis.


Assuntos
Derivados de Benzeno/química , Complexos de Coordenação/química , Metais/química , Compostos Organometálicos/química , Carbono/química , Catálise , Complexos de Coordenação/síntese química , Ligantes , Compostos Organometálicos/síntese química , Paládio/química , Rutênio/química , Elementos de Transição/química
7.
Nat Commun ; 12(1): 3712, 2021 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-34140507

RESUMO

Metalloenzymes are 40% of all enzymes and can perform all seven classes of enzyme reactions. Because of the physicochemical similarities between the active sites of metalloenzymes and inactive metal binding sites, it is challenging to differentiate between them. Yet distinguishing these two classes is critical for the identification of both native and designed enzymes. Because of similarities between catalytic and non-catalytic  metal binding sites, finding physicochemical features that distinguish these two types of metal sites can indicate aspects that are critical to enzyme function. In this work, we develop the largest structural dataset of enzymatic and non-enzymatic metalloprotein sites to date. We then use a decision-tree ensemble machine learning model to classify metals bound to proteins as enzymatic or non-enzymatic with 92.2% precision and 90.1% recall. Our model scores electrostatic and pocket lining features as more important than pocket volume, despite the fact that volume is the most quantitatively different feature between enzyme and non-enzymatic sites. Finally, we find our model has overall better performance in a side-to-side comparison against other methods that differentiate enzymatic from non-enzymatic sequences. We anticipate that our model's ability to correctly identify which metal sites are responsible for enzymatic activity could enable identification of new enzymatic mechanisms and de novo enzyme design.


Assuntos
Enzimas/química , Aprendizado de Máquina , Metaloproteínas/química , Metaloproteínas/metabolismo , Metais/química , Algoritmos , Sítios de Ligação , Catálise , Domínio Catalítico , Bases de Dados de Proteínas , Modelos Moleculares , Eletricidade Estática
8.
Eur J Radiol ; 141: 109811, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34102563

RESUMO

PURPOSE: To evaluate suitable iterative metal artifact reduction (iMAR) presets for titanium neurosurgical clips and burr hole covers (BHCs) on postoperative non-contrast computed tomography (NCCT). METHOD: Twenty-two patients who underwent NCCT after intracranial aneurysmal clipping were included. NCCT images were postprocessed using eight currently available iMAR presets. In each image, a circular region of interest (ROI) was placed around clip, BHC, and on parietal lobe as reference. Standard deviation (SD) and attenuation value (HU) were measured in each ROI to obtain artifact index (AI) and contrast-to-noise ratio (CNR). For each iMAR preset, SD, AI, HU, and CNR were compared with those without iMAR for clips and BHCs. Visual assessment around each clip and BHC was performed by two neuroradiologists using three-point visual score (VS) (1 = no apparent, 2 = minor, and 3 = severe artifacts). RESULTS: Among the presets, the neuro-coils preset (iMAR-NC) showed the lowest SD, AI, and VS for clips (P < 0.001). For BHCs, HU, CNR, and VS with iMAR-NC were significantly higher than those without iMAR (P < 0.001). SD, AI, and VS with the shoulder implants preset (iMAR-ShI) were significantly lower than those without iMAR for clips (P = 0.002, 0.002, and P <  0.001, respectively). For BHCs, VS with iMAR-ShI was lowest among the presets (P = 0.004). CONCLUSIONS: Although iMAR-NC reduces metal artifacts from clips, it strengthens artifacts from BHCs. For postoperative NCCT, iMAR-ShI most effectively reduces metal artifacts from both clips and BHCs in a single preset.


Assuntos
Artefatos , Titânio , Algoritmos , Encéfalo , Humanos , Metais , Instrumentos Cirúrgicos , Tomografia Computadorizada por Raios X
9.
Food Chem ; 362: 130168, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34090045

RESUMO

Multielement analysis and chemometric methods were proposed to discriminate the Sorrento lemon (PGI) juices according to geographical origin. In 2018 and 2019, 169 fruits from three farms in PGI area and two in not-PGI area were collected and analysed for essential and not-essential elements by ICP-MS. The PCA of multielement fingerprinting grouped lemon juices from PGI farms revealing a strong differentiation at small geographical scale. The S-LDA discriminated lemon juices for Mo, Ba, Rb, Mg, Co, Ca, Fe, Sr on the two production years, giving 97.7% correct classification, 98.5% accuracy and 93.8% external validation. The good correlation lemon juice vs cultivation soil and the soil discrimination by not-essential elements suggested the use of these elements as reliable indicators of lemon juice provenances. Despite lowering the number of variables, constituted by not-essential elements Ba, Rb, Ti, Co, the use of S-QDA discriminated the lemons juices with 87.5% accuracy and 83.9% validation.


Assuntos
Citrus/química , Análise de Alimentos/métodos , Metais/análise , Solo/química , Quimioinformática/métodos , Análise Discriminante , Análise de Alimentos/estatística & dados numéricos , Frutas/química , Sucos de Frutas e Vegetais/análise , Itália
10.
Nat Protoc ; 16(7): 3695-3715, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34099942

RESUMO

Super-resolution fluorescence imaging that surpasses the classical optical resolution limit is widely utilized for resolving the spatial organization of biological structures at molecular length scales. In one example, single-molecule localization microscopy, the lateral positions of single molecules can be determined more precisely than the diffraction limit if the camera collects individual photons separately. Using several schemes that introduce engineered optical aberrations in the imaging optics, super-resolution along the optical axis (perpendicular to the sample plane) has been achieved, and single-molecule localization microscopy has been successfully applied for the study of 3D biological structures. Nonetheless, the achievable axial localization accuracy is typically three to five times worse than the lateral localization accuracy. Only a few exceptional methods based on interferometry exist that reach nanometer 3D super-resolution, but they involve enormous technical complexity and restricted sample preparations that inhibit their widespread application. We developed metal-induced energy transfer imaging for localizing fluorophores along the axial direction with nanometer accuracy, using only a conventional fluorescence lifetime imaging microscope. In metal-induced energy transfer, experimentally measured fluorescence lifetime values increase linearly with axial distance in the range of 0-100 nm, making it possible to calculate their axial position using a theoretical model. If graphene is used instead of the metal (graphene-induced energy transfer), the same range of lifetime values occurs over a shorter axial distance (~25 nm), meaning that it is possible to get very accurate axial information at the scale of a membrane bilayer or a molecular complex in a membrane. Here, we provide a step-by-step protocol for metal- and graphene-induced energy transfer imaging in single molecules, supported lipid bilayer and live-cell membranes. Depending on the sample preparation time, the complete duration of the protocol is 1-3 d.


Assuntos
Transferência de Energia , Grafite/química , Metais/química , Nanotecnologia/métodos , Imagem Individual de Molécula/métodos , Animais , Linhagem Celular Tumoral , Sobrevivência Celular , Análise de Dados , Cães , Corantes Fluorescentes/química , Humanos , Imageamento Tridimensional , Células Madin Darby de Rim Canino , Microscopia de Fluorescência , Interface Usuário-Computador
11.
Food Chem ; 362: 130176, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34111692

RESUMO

In the present work, multivariate designs were used to optimize an alkaline dissolution, assisted by ultrasound energy, procedure of goat meat using tetramethylammonium hydroxide (TMAH) aiming to determine Ca, Cu, Fe, K, Mg, Na and Zn by flame atomic absorption (FAAS) and emission (FAES) spectrometry. The optimal conditions found for the dissolution were in the following ranges: 0.4-0.5 g for the sample mass, 12-15 min of sonication and using 700-1000 µL of 25% TMAH at a temperature of 50 °C. The obtained limits of quantification varied between 0.221 (Mg) and 7.60 (Ca) µg g-1. Accuracy was assessed by comparing the results obtained by applying the proposed method with the digestion in an acid medium using a digesting block and by analyzing bovine liver certified reference material. The application of a t-test revealed that, at a 95% confidence level, there were no significant differences between the values obtained.


Assuntos
Análise de Alimentos/métodos , Carne/análise , Metais/análise , Espectrofotometria Atômica/métodos , Animais , Análise de Alimentos/estatística & dados numéricos , Cabras , Análise Multivariada , Compostos de Amônio Quaternário/química , Solubilidade , Espectrofotometria Atômica/estatística & dados numéricos , Temperatura
12.
Appl Microbiol Biotechnol ; 105(13): 5689-5699, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34160647

RESUMO

Owing to the prevalence of cadmium contamination and its serious hazards, it is important to establish an efficient and low-cost monitoring technique for the detection of the heavy metal cadmium. In this study, we first designed 30 cadmium whole-cell biosensors (WCBs) using different combinations of detection elements, reporting elements, and the host. The best performing WCB KT-5-R with Pseudomonas putida KT2440 as the host and composed of CadR and mCherry was selected for further analysis and engineering. In order to enhance its sensitivity, a positive feedback amplifier was added or the gene dosage of the reporter gene was increased. The WCB with the T7RNAP amplification module, p2T7RNAPmut-68, had the best performance and improved tolerance to cadmium with a detection limit of 0.01 µM, which is the WHO standard. It also showed excellent specificity toward cadmium when assayed with mixed metal ions. This study demonstrated the power of circuit engineering in WCB design and provided valuable insights for the development of other WCBs. KEY POINTS: • KT-5-R was selected after prescreening and engineered for better performance. • Using multi-copy reporters and the T7RNAP amplifier greatly improved the performance. • p2T7RNAPmut-68 had a detection limit of 0.01 µM and improved tolerance to cadmium.


Assuntos
Técnicas Biossensoriais , Pseudomonas putida , Cádmio , Genes Reporter , Metais , Pseudomonas putida/genética
13.
Environ Sci Technol ; 55(13): 9074-9086, 2021 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-34132542

RESUMO

Children who live near coal-fired power plants are exposed to coal fly ash, which is stored in landfills and surface impoundments near residential communities. Fly ash has the potential to be released as fugitive dust. Using data collected from 263 children living within 10 miles of coal ash storage facilities in Jefferson and Bullitt Counties, Kentucky, USA, we quantified the elements found in nail samples. Furthermore, using principal component analysis (PCA), we investigated whether metal(loid)s that are predominately found in fly ash loaded together to indicate potential exposure to fly ash. Concentrations of several neurotoxic metal(loid)s, such as chromium, manganese, and zinc, were higher than concentrations reported in other studies of both healthy and environmentally exposed children. From PCA, it was determined that iron, aluminum, and silicon in fly ash were found to load together in the nails of children living near coal ash storage facilities. These metal(loid)s were also highly correlated with each other. Last, results of geospatial analyses partially validated our hypothesis that children's proximity to power plants was associated with elevated levels of concentrations of fly ash metal(loid)s in nails. Taken together, nail samples may be a powerful tool in detecting exposure to fly ash.


Assuntos
Cinza de Carvão , Centrais Elétricas , Criança , Carvão Mineral , Cinza de Carvão/análise , Poeira/análise , Humanos , Metais
14.
Environ Sci Technol ; 55(13): 8502-8513, 2021 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-34152746

RESUMO

Mineral deposits containing commercially exploitable metals are of interest for seabed mineral extraction in both the deep sea and shallow sea areas. However, the development of seafloor mining is underpinned by high uncertainties on the implementation of the activities and their consequences for the environment. To avoid unbridled expansion of maritime activities, the environmental risks of new types of activities should be carefully evaluated prior to permitting them, yet observational data on the impacts is mostly missing. Here, we examine the environmental risks of seabed mining using a causal, probabilistic network approach. Drawing on a series of expert interviews, we outline the cause-effect pathways related to seabed mining activities to inform quantitative risk assessments. The approach consists of (1) iterative model building with experts to identify the causal connections between seabed mining activities and the affected ecosystem components and (2) quantitative probabilistic modeling. We demonstrate the approach in the Baltic Sea, where seabed mining been has tested and the ecosystem is well studied. The model is used to provide estimates of mortality of benthic fauna under alternative mining scenarios, offering a quantitative means to highlight the uncertainties around the impacts of mining. We further outline requirements for operationalizing quantitative risk assessments in data-poor cases, highlighting the importance of a predictive approach to risk identification. The model can be used to support permitting processes by providing a more comprehensive description of the potential environmental impacts of seabed resource use, allowing iterative updating of the model as new information becomes available.


Assuntos
Ecossistema , Mineração , Meio Ambiente , Metais , Minerais
15.
Ecotoxicol Environ Saf ; 221: 112437, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34153540

RESUMO

Agricultural soils are receiving higher inputs of trace elements (TEs) from anthropogenic activities. Application of nanoparticles (NPs) in agriculture as nano-pesticides and nano-fertilizers has gained rapid momentum worldwide. The NPs-based fertilizers can facilitate controlled-release of nutrients which may be absorbed by plants more efficiently than conventional fertilizers. Due to their large surface area with high sorption capacity, NPs can be used to reduce excess TEs uptake by plants. The present review summarizes the effects of NPs on plant growth, photosynthesis, mineral nutrients uptake and TEs concentrations. It also highlights the possible mechanisms underlying NPs-mediated reduction of TEs toxicity at the soil and plant interphase. Nanoparticles are effective in immobilization of TEs in soil through alteration of their speciation and improving soil physical, chemical, and biological properties. At the plant level, NPs reduce TEs translocation from roots to shoots by promoting structural alterations, modifying gene expression, and improving antioxidant defense systems. However, the mechanisms underlying NPs-mediated TEs uptake and toxicity reduction vary with NPs type, mode of application, time of NPs exposure, and plant conditions (e.g., species, cultivars, and growth rate). The review emphasizes that NPs may provide new perspectives to resolve the problem of TEs toxicity in crop plants which may also reduce the food security risks. However, the potential of NPs in metal-contaminated soils is only just starting to be realized, and additional studies are required to explore the mechanisms of NPs-mediated TEs immobilization in soil and uptake by plants. Such future knowledge gap has been highlighted and discussed.


Assuntos
Nanopartículas , Plantas/efeitos dos fármacos , Oligoelementos/metabolismo , Oligoelementos/toxicidade , Agricultura , Metais/metabolismo , Metais/toxicidade , Raízes de Plantas/metabolismo , Plantas/metabolismo , Solo/química , Poluentes do Solo/metabolismo , Poluentes do Solo/toxicidade
16.
Ecotoxicol Environ Saf ; 221: 112443, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34166939

RESUMO

It is important to assess the toxic effects posed by soil pollutants toward plants. However, plant toxicology experiments normally involve a considerable amount of manpower, consumables and time. Therefore, the use of metal toxicity prediction models, independent of toxicity tests, is critical. In this study, we investigated the toxicity of different metal ions to wheat using hydroponic experiments. We employed the methods of soft-hard ion grouping, soft-hard ligand theory and K (conditional binding constant based on the biotic ligand model principle) in combination with hydroponic experiments to explore the application of quantitative ion character-activity relationships in predicting phytotoxicity. The results showed that the toxicity of the 19 metal ions tested varied significantly, with EC50 ranging from 0.27 µM to 4463.36 µM. The linear regression relationships between the toxicity of these metal ions and their physicochemical properties were poor (R2 = 0.237-0.331, p < 0.05). These relationships were improved after grouping the metals according to the soft-hard theory (R2 = 0.527-0.744 and p < 0.05 for soft ions; R2 = 0.445-0.743 and p < 0.05 for hard ions). The application of soft-hard ligand theory, based on the binding affinity of the metals to the ligands, showed poor prediction of the phytotoxicity of metals, with R2 = 0.413 (p = 0.024) for the softness consensus scale (σCon) and R2 = 0.348 (p = 0.218) for the normalized hard ligands scale (HLScale). However, the method of K provided the closest fit in predicting toxicity (R2 = 0.803, p < 0.001). Our results showed that the application of soft-hard ion grouping and log K can improve prediction of the phytotoxicity of metals relatively well, which can potentially be used for deriving the toxicity of elements with limited toxicity data.


Assuntos
Metais/toxicidade , Testes de Toxicidade/métodos , Triticum/efeitos dos fármacos , Íons/química , Ligantes , Poluentes do Solo/toxicidade
17.
Nucleic Acids Res ; 49(11): 6296-6314, 2021 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-34107019

RESUMO

Metal-induced genes are usually transcribed at relatively low levels under normal conditions and are rapidly activated by heavy metal stress. Many of these genes respond preferentially to specific metal-stressed conditions. However, the mechanism by which the general transcription machinery discriminates metal stress from normal conditions and the regulation of MTF-1-meditated metal discrimination are poorly characterized. Using a focused RNAi screening in Drosophila Schneider 2 (S2) cells, we identified a novel activator, the Drosophila gawky, of metal-responsive genes. Depletion of gawky has almost no effect on the basal transcription of the metallothionein (MT) genes, but impairs the metal-induced transcription by inducing the dissociation of MTF-1 from the MT promoters and the deficient nuclear import of MTF-1 under metal-stressed conditions. This suggests that gawky serves as a 'checkpoint' for metal stress and metal-induced transcription. In fact, regular mRNAs are converted into gawky-controlled transcripts if expressed under the control of a metal-responsive promoter, suggesting that whether transcription undergoes gawky-mediated regulation is encrypted therein. Additionally, lack of gawky eliminates the DNA binding bias of MTF-1 and the transcription preference of metal-specific genes. This suggests a combinatorial control of metal discrimination by gawky, MTF-1, and MTF-1 binding sites.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Metais/toxicidade , Fatores de Transcrição/metabolismo , Ativação Transcricional , Transporte Ativo do Núcleo Celular , Animais , Linhagem Celular , Núcleo Celular/metabolismo , Cobre/toxicidade , Proteínas de Drosophila/genética , Proteínas de Drosophila/fisiologia , Drosophila melanogaster/efeitos dos fármacos , Drosophila melanogaster/metabolismo , Metalotioneína/genética , Regiões Promotoras Genéticas , Interferência de RNA , Splicing de RNA , Estresse Fisiológico/genética
18.
Nat Commun ; 12(1): 3824, 2021 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-34158483

RESUMO

Low-dimensional van der Waals (vdW) materials can harness tightly confined polaritonic waves to deliver unique advantages for nanophotonic biosensing. The reduced dimensionality of vdW materials, as in the case of two-dimensional graphene, can greatly enhance plasmonic field confinement, boosting sensitivity and efficiency compared to conventional nanophotonic devices that rely on surface plasmon resonance in metallic films. Furthermore, the reduction of dielectric screening in vdW materials enables electrostatic tunability of different polariton modes, including plasmons, excitons, and phonons. One-dimensional vdW materials, particularly single-walled carbon nanotubes, possess unique form factors with confined excitons to enable single-molecule detection as well as in vivo biosensing. We discuss basic sensing principles based on vdW materials, followed by technological challenges such as surface chemistry, integration, and toxicity. Finally, we highlight progress in harnessing vdW materials to demonstrate new sensing functionalities that are difficult to perform with conventional metal/dielectric sensors.


Assuntos
Materiais Biocompatíveis/análise , Técnicas Biossensoriais/métodos , Grafite/química , Metais/química , Nanoestruturas/química , Ressonância de Plasmônio de Superfície/métodos , Tamanho da Partícula , Espectrofotometria Infravermelho , Propriedades de Superfície , Termodinâmica
19.
Nat Commun ; 12(1): 3867, 2021 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-34162839

RESUMO

Enzymes can evolve new catalytic activity when environmental changes present them with novel substrates. Despite this seemingly straightforward relationship, factors other than the direct catalytic target can also impact adaptation. Here, we characterize the catalytic activity of a recently evolved bacterial methyl-parathion hydrolase for all possible combinations of the five functionally relevant mutations under eight different laboratory conditions (in which an alternative divalent metal is supplemented). The resultant adaptive landscapes across this historical evolutionary transition vary in terms of both the number of "fitness peaks" as well as the genotype(s) at which they are found as a result of genotype-by-environment interactions and environment-dependent epistasis. This suggests that adaptive landscapes may be fluid and molecular adaptation is highly contingent not only on obvious factors (such as catalytic targets), but also on less obvious secondary environmental factors that can direct it towards distinct outcomes.


Assuntos
Adaptação Fisiológica/genética , Bactérias/genética , Proteínas de Bactérias/genética , Epistasia Genética , Hidrolases/genética , Sequência de Aminoácidos , Bactérias/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Biocatálise , Evolução Molecular , Interação Gene-Ambiente , Genótipo , Hidrolases/química , Hidrolases/metabolismo , Cinética , Metais/química , Metais/metabolismo , Metil Paration/química , Metil Paration/metabolismo , Mutação , Domínios Proteicos , Homologia de Sequência de Aminoácidos
20.
Nat Commun ; 12(1): 3898, 2021 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-34162854

RESUMO

One topical area of supramolecular chemistry is the binding of anionic species but despite the importance of anions in diverse cellular processes and for cancer development, anion receptors or 'binders' have received little attention as potential anti-cancer therapeutics. Here we report self-assembling trimetallic cryptands (e.g. [L2(Metal)3]6+ where Metal = Cu2+, Zn2+ or Mn2+) which can encapsulate a range of anions and which show metal-dependent differences in chemical and biological reactivities. In cell studies, both [L2Cu3]6+ and [L2Zn3]6+ complexes are highly toxic to a range of human cancer cell lines and they show significant metal-dependent selective activity towards cancer cells compared to healthy, non-cancerous cells (by up to 2000-fold). The addition of different anions to the complexes (e.g. PO43-, SO42- or PhOPO32-) further alters activity and selectivity allowing the activity to be modulated via a self-assembly process. The activity is attributed to the ability to either bind or hydrolyse phosphate esters and mechanistic studies show differential and selective inhibition of multiple kinases by both [L2Cu3]6+ and [L2Zn3]6+ complexes but via different mechanisms.


Assuntos
Ânions/química , Antineoplásicos/química , Complexos de Coordenação/química , Metais/química , Células A549 , Antineoplásicos/farmacologia , Autofagia/efeitos dos fármacos , Western Blotting , Linhagem Celular , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Complexos de Coordenação/farmacologia , Cristalografia por Raios X , Células HCT116 , Células HT29 , Humanos , Concentração Inibidora 50 , Neoplasias/metabolismo , Neoplasias/patologia , Fosfotransferases/antagonistas & inibidores , Fosfotransferases/metabolismo
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