Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 117
Filtrar
Mais filtros

País/Região como assunto
Intervalo de ano de publicação
1.
Biochem Biophys Res Commun ; 724: 150223, 2024 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-38852505

RESUMO

SWI/SNF chromatin remodeling complexes play a key role in gene transcription as epigenetic regulators and are typically considered to act as tumor suppressors in cancers. Compared to other cancer-related components of the SWI/SNF complex, research on SMARCC2, a component of the initial BAF core, has been relatively limited. This study aimed to elucidate the role of SMARCC2 in breast cancer by employing various in vitro and in vivo methods including cell proliferation assays, mammosphere formation, and xenograft models, complemented by RNA-seq, ATAC-seq, and ChIP analyses. The results showed that SMARCC2 silencing surprisingly led to the suppression of breast tumorigenesis, indicating a pro-tumorigenic function for SMARCC2 in breast cancer, which contrasts with the roles of other SWI/SNF subunits. In addition, SMARCC2 depletion reduces cancer stem cell features of breast cancer cells. Mechanistic study showed that SMARCC2 silencing downregulated the oncogenic Ras-PI3K signaling pathway, likely by directly regulating the chromatin accessibility of the enhancers of the key genes such as PIK3CB. Together, these results expand our understanding of the SWI/SNF complex's role in cancer development and identify SMARCC2 as a promising new target for breast cancer therapies.


Assuntos
Neoplasias da Mama , Cromatina , Inativação Gênica , Humanos , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Feminino , Cromatina/metabolismo , Cromatina/genética , Animais , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Camundongos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proliferação de Células/genética , Carcinogênese/genética , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Transdução de Sinais , Camundongos Nus , Montagem e Desmontagem da Cromatina/genética
2.
Environ Res ; 220: 115172, 2023 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-36584849

RESUMO

In alkaline soil, abundant carbonates will mobilize uranium (U) and increase its ecotoxicity, which is a serious threat to crop growth. However, the knowledge of U remediation in alkaline soils remains very limited. In this study, U-contaminated alkaline soil (tillage layer) was collected from the Ili mining area of Xinjiang, the soil remediation was carried out by using phosphorus (P) fertilizers of different solubility (including KH2PO4, Ca(H2PO4)2, CaHPO4, and Ca3(PO4)2), and the pathways and mechanisms of U passivation in the alkaline soil were revealed. The results showed that water-soluble P fertilizers, KH2PO4 and Ca(H2PO4)2, were highly effective at immobilizing U, and significantly reduced the bioavailability of soil U. The exchangeable U was reduced by 70.5 ± 0.1% (KH2PO4) and 68.2 ± 1.9% (Ca(H2PO4)2), which was converted into the Fe-Mn oxide-bound and residual phases. Pot experiments showed that soil remediation by KH2PO4 significantly promoted crop growth, especially for roots, and reduced U uptake in crops by 94.5 ± 1.0%. The immobilization of U by KH2PO4 could be attributed to the release of phosphate anions, which react with the uranyl ion (UO22+) forming a stable mineral of meta-ankoleite and enhancing the binding of UO22+ to the soil Fe-Mn oxides. In addition, KH2PO4 dissolution produces acidity and P fertilizer, which can reduce soil alkalinity and improve crop growth. The findings in this work demonstrate that a rational application of P fertilizer can effectively, conveniently, and cheaply remediate U contamination and improve crop yield and safety on alkaline farmland.


Assuntos
Poluentes do Solo , Urânio , Fósforo , Fertilizantes/análise , Poluentes do Solo/análise , Solo
3.
Cancer Sci ; 113(2): 553-564, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34904330

RESUMO

Treacle ribosome biogenesis factor 1 (TCOF1) is a nucleolar factor that regulates ribosomal DNA (rDNA) transcription in the nucleolus. TCOF1 has been previously reported to be implicated in Treacher Collins-Franceschetti syndrome (TCS), a congenital disorder of craniofacial development. Except TCS, TCOF1 has not been reported to be involved in other diseases so far. Here, we show that TCOF1 expression is aberrantly elevated in human hepatocellular carcinoma (HCC) and correlates with HCC progression and poor outcome. In vitro and in vivo studies reveal oncogenic roles of TCOF1 in HCC. Mechanistically, TCOF1 regulates KRAS-activated genes and epithelial-mesenchymal transition (EMT) genes in HCC and is required for the increased ribosomal RNA (rRNA) production, a hallmark of cancer. Interestingly, our analysis reveals an inverse correlation between TCOF1 expression and tumor infiltration of antitumor immune cells, suggesting that TCOF1 may also have an important impact on antitumor immune responses in HCC. Together, our findings support a model in which TCOF1 coordinates oncogenic activation and rRNA production to promote HCC tumorigenesis. The inverse correlation between TCOF1 expression and the infiltration of antitumor immune cells opens a new avenue to understanding the promoting role of TCOF in HCC tumorigenesis.


Assuntos
Carcinoma Hepatocelular/patologia , Neoplasias Hepáticas/patologia , Proteínas Nucleares/metabolismo , Fosfoproteínas/metabolismo , RNA Ribossômico/metabolismo , Animais , Apoptose , Carcinogênese , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/imunologia , Carcinoma Hepatocelular/metabolismo , Ciclo Celular , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Progressão da Doença , Transição Epitelial-Mesenquimal/genética , Humanos , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/imunologia , Neoplasias Hepáticas/metabolismo , Linfócitos do Interstício Tumoral , Camundongos , Proteínas Nucleares/genética , Fosfoproteínas/genética , Prognóstico , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , RNA Ribossômico/genética , Transcrição Gênica
4.
Proc Natl Acad Sci U S A ; 113(16): 4428-33, 2016 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-27044105

RESUMO

InDrosophila, homologous chromosome pairing leads to "transvection," in which the enhancer of a gene can regulate the allelic transcription intrans.Interallelic interactions were also observed in vegetative diploid budding yeast, but their functional significance is unknown. Here, we show that aGAL1reporter can interact with its homologous allele and affect its expression. By ectopically inserting two allelic reporters, one driven by wild-typeGAL1promoter (WTGAL1pr) and the other by a mutant promoter with delayed response to galactose induction, we found that the two reporters physically associate, and the WTGAL1prtriggers synchronized firing of the defective promoter and accelerates its activation without affecting its steady-state expression level. This interaction and the transregulatory effect disappear when the same reporters are located at nonallelic sites. We further demonstrated that the activator Gal4 is essential for the interallelic interaction, and the transregulation requires fully activated WTGAL1prtranscription. The mechanism of this phenomenon was further discussed. Taken together, our data revealed the existence of interallelic gene regulation in yeast, which serves as a starting point for understanding long-distance gene regulation in this genetically tractable system.


Assuntos
Alelos , Galactoquinase/genética , Regulação Fúngica da Expressão Gênica , Mutação , Regiões Promotoras Genéticas , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Transcrição Gênica , Galactoquinase/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo
5.
J Environ Manage ; 231: 268-274, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30347345

RESUMO

This study involved fabricating biogenic Fe(III) flocs enriched from municipal sludge using microbial nitrate-dependent anaerobic Fe(II)-oxidizing (NAFO) processes. The research focused on bacterial community compositions and physicochemical properties of the biogenic Fe(III) flocs and their ability to adsorb arsenic (As). High-throughput sequencing analysis showed that significant microbial succession occurs in the raw sludge after the NAFO processes. The predominant bacterial communities in the biogenic Fe(III) flocs included Rhodanobacter, Parvibaculum, Gemmatimonas and Segetibacter genera. Microscopic and spectroscopic analyses included scanning electron microscopy - energy disperse spectroscopy (SEM-EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. These tests indicated that biogenic Fe(III) flocs were a mixture of NAFO bacteria and nanosized, poorly crystalline Fe(III) oxide particles. Batch experiments showed that after 120 min of reaction time, more than 95% of As(III) and As(V) (at an initial concentrations of 0.25 mg/L) were effectively removed with 120 ppm biogenic Fe(III) flocs. In addition, biogenic Fe(III) flocs removed As more effectively than abiotic Fe(III) flocs. These findings indicated that biogenic Fe(III) flocs produced from municipal sludge using NAFO processes performed well in removing As.


Assuntos
Arsênio , Compostos Férricos , Nitratos , Oxirredução , Esgotos
7.
Adv Appl Microbiol ; 101: 137-168, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29050665

RESUMO

Following the development of nuclear science and technology, uranium contamination has been an ever increasing concern worldwide because of its potential for migration from the waste repositories and long-term contaminated environments. Physical and chemical techniques for uranium pollution are expensive and challenging. An alternative to these technologies is microbially mediated uranium bioremediation in contaminated water and soil environments due to its reduced cost and environmental friendliness. To date, four basic mechanisms of uranium bioremediation-uranium bioreduction, biosorption, biomineralization, and bioaccumulation-have been established, of which uranium bioreduction and biomineralization have been studied extensively. The objective of this review is to provide an understanding of recent developments in these two fields in relation to relevant microorganisms, mechanisms, influential factors, and obstacles.


Assuntos
Bactérias/metabolismo , Fungos/metabolismo , Solo/química , Urânio/metabolismo , Biodegradação Ambiental , Oxirredução , Urânio/análise
8.
Nucleic Acids Res ; 43(15): 7292-305, 2015 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-26082499

RESUMO

Divergent gene pairs (DGPs) are abundant in eukaryotic genomes. Since two genes in a DGP potentially share the same regulatory sequence, one might expect that they should be co-regulated. However, an inspection of yeast DGPs containing cell-cycle or stress response genes revealed that most DGPs are differentially-regulated. The mechanism underlying DGP differential regulation is not understood. Here, we showed that co- versus differential regulation cannot be explained by genetic features including promoter length, binding site orientation, TATA elements, nucleosome distribution, or presence of non-coding RNAs. Using time-lapse fluorescence microscopy, we carried out an in-depth study of a differentially regulated DGP, PFK26-MOB1. We found that their differential regulation is mainly achieved through two DNA-binding factors, Tbf1 and Mcm1. Similar to 'enhancer-blocking insulators' in higher eukaryotes, these factors shield the proximal promoter from the action of more distant transcription regulators. We confirmed the blockage function of Tbf1 using synthetic promoters. We further presented evidence that the blockage mechanism is widely used among genome-wide DGPs. Besides elucidating the DGP regulatory mechanism, our work revealed a novel class of insulators in yeast.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Regulação Fúngica da Expressão Gênica , Proteína 1 de Manutenção de Minicromossomo/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição/metabolismo , Sítios de Ligação , Proteínas de Ciclo Celular/genética , Genoma Fúngico , Nucleossomos/metabolismo , Fosfoproteínas/genética , Regiões Promotoras Genéticas , RNA não Traduzido/genética , Elementos Reguladores de Transcrição , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , TATA Box
9.
Curr Microbiol ; 70(1): 27-34, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25141964

RESUMO

The knowledge of the effects of Sb(V) on the physiological characteristics of cyanobacteria was still limited. In the present study, responses of photosystem I and II (PSI and PSII), cyclic electron flow (CEF), and interphotosystem electron transport of Microcystis aeruginosa to 5-100 mg/l Sb(V) were synchronously measured using the Dual-PAM-100. 5 mg/l Sb (V) significantly inhibited PSII activity, but had no significant effects on PSI activity. At higher concentrations of Sb(V), the quantum yield and electron transport of PSI were less affected compared to PSII. The ratio of Y(II)/Y(I) significantly decreased with increasing Sb(V) concentration. It decreased from 0.7 for control to 0.4 for 100 mg/l Sb(V)-treated cells, indicating that the change of the distribution of quantum yields between two photosystems and more serious inhibition of PSII under stress of Sb(V) compared to PSI. CEF was activated associated with the inhibition of linear electron flow after exposure to Sb(V). The contribution of Y(CEF) to the quantum yield and activity of PSI increased with increasing Sb(V) concentrations. The cyclic electron transport rate made a significant contribution to electron transport rate of PSI, especially at high Sb(V) concentration (100 mg/l) and high illumination (above 555 µmol photons/m(2)/s). The stimulation of CEF was essential for the higher tolerance of PSI than PSII to Sb(V).


Assuntos
Antimônio/metabolismo , Proteínas de Bactérias/metabolismo , Microcystis/metabolismo , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Proteínas de Bactérias/genética , Transporte de Elétrons , Microcystis/genética , Complexo de Proteína do Fotossistema I/genética , Complexo de Proteína do Fotossistema II/genética
10.
Biochim Biophys Acta ; 1829(11): 1218-24, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23891849

RESUMO

C-Jun is a major transcription factor belonging to the activating protein 1 (AP-1) family. Phosphorylation has been shown to be critical for c-Jun activation and stability. Here, we report that Jra, the Drosophila Jun protein, is acetylated in vivo. We demonstrate that the acetylation of Jra leads to its rapid degradation in response to osmotic stress. Intriguingly, we also found that Jra phosphorylation antagonized its acetylation, indicating the opposite roles of acetylation and phosphorylation in Jra degradation process under osmotic stress. Our results provide new insights into how c-Jun proteins are precisely regulated by the interplay of different posttranslational modifications.


Assuntos
Drosophila/metabolismo , Proteínas Proto-Oncogênicas c-jun/metabolismo , Acetilação , Sequência de Aminoácidos , Animais , Humanos , Dados de Sequência Molecular , Fosforilação , Proteínas Proto-Oncogênicas c-jun/química , Homologia de Sequência de Aminoácidos , Ubiquitinação
11.
Pestic Biochem Physiol ; 115: 23-31, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25307462

RESUMO

The herbicidal effects of harmaline extracted from Peganum harmala seed on cell growth and photosynthesis of green algae Chlorella pyrenoidosa were investigated using chlorophyll a fluorescence and thermoluminescence techniques. Exposure to harmaline inhibited cell growth, pigments contents and oxygen evolution of C. pyrenoidosa. Oxygen evolution was more sensitive to harmaline toxicity than cell growth or the whole photosystem II (PSII) activity, maybe it was the first target site of harmaline. The JIP-test parameters showed that harmaline inhibited the donor side of PSII. Harmaline decreased photochemical efficiency and electron transport flow of PSII but increased the energy dissipation. The charge recombination was also affected by harmaline. Amplitude of the fast phase decreased and the slow phase increased at the highest level of harmaline. Electron transfer from QA(-) to QB was inhibited and backward electron transport flow from QA(-) to oxygen evolution complex was enhanced at 10 µg mL(-1) harmaline. Exposure to 10 µg mL(-1) harmaline caused appearance of C band in thermoluminescence. Exposure to 5 µg mL(-1) harmaline inhibited the formation of proton gradient. The highest concentration of harmaline treatment inhibited S3QB(-) charge recombination but promoted formation of QA(-)YD(+) charge pairs. P. harmala harmaline may be a promising herbicide because of its inhibition of cell growth, pigments synthesis, oxygen evolution and PSII activities.


Assuntos
Chlorella/efeitos dos fármacos , Clorofila/metabolismo , Harmalina/farmacologia , Herbicidas/farmacologia , Peganum/química , Fotossíntese/efeitos dos fármacos , Extratos Vegetais/farmacologia , Chlorella/química , Chlorella/crescimento & desenvolvimento , Chlorella/metabolismo , Clorofila/química , Clorofila A , Transporte de Elétrons/efeitos dos fármacos , Fluorescência , Harmalina/isolamento & purificação , Herbicidas/isolamento & purificação , Medições Luminescentes
12.
J Hazard Mater ; 479: 135649, 2024 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-39208625

RESUMO

The toxicity of microplastics (MPs) to aquatic animals is closely related to the presence and release kinetics of contained additives, as most plastic products contain various additives. However, the relationship between the occurrence and release of additives from MPs, and their individual or combined toxicity remains unclear. In this study, the nanoscale distribution and release of tetrabromobisphenol A (TBBPA, a common flame retardant with endocrine-disrupting effect) in polystyrene (PS) MPs, and the long-term (60 days) toxicity of TBBPA and MPs containing TBBPA (at doses of 0 %, 1 %, 10 %, w/w) to Xenopus tropicalis tadpoles were investigated. Exposure to 10 µg/L TBBPA alone was the most toxics, while the encapsulation of TBBPA in MPs significantly delayed its lethal toxicity to tadpoles by inhibiting the rapid and extensive release of TBBPA. PS MPs alone and MPs containing 10 % TBBPA exhibited delayed survival toxicity compared to TBBPA alone, whereas PS MPs containing 1 % TBBPA did not show this effect but inhibited growth. These findings suggest that chronic toxicity assessments should be based on long-term (months or even years) exposure experiments due to the encapsulation-controlled slow release of toxic additives.


Assuntos
Disruptores Endócrinos , Microplásticos , Bifenil Polibromatos , Xenopus , Xenopus/crescimento & desenvolvimento , Bifenil Polibromatos/análise , Bifenil Polibromatos/toxicidade , Larva/efeitos dos fármacos , Microplásticos/química , Microplásticos/toxicidade , Espectrometria de Massas em Tandem , Bioacumulação , Testes de Toxicidade , Disruptores Endócrinos/toxicidade
13.
Water Res ; 258: 121802, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38796914

RESUMO

Rice paddies are globally important sources of methane emissions and also active regions for methane consumption. However, the impact of fluctuating groundwater levels on methane cycling has received limited attention. In this study, we delved into the activity and microbial mechanisms underlying anaerobic oxidation of methane (AOM) in paddy fields. A comprehensive approach was employed, including 13C stable isotope assays, inhibition experiments, real-time quantitative reverse transcription PCR, metagenomic sequencing, and binning technology. Geochemical profiles revealed the abundant coexistence of both methane and electron acceptors in the groundwater table fluctuation (GTF) zone, at a depth of 40-60 cm. Notably, the GTF zone exhibited the highest rate of AOM, potentially linked to the reduction of iron oxides and nitrate. Within this zone, Candidatus Methanoperedens (belonging to the ANME-2d group) dominated the Archaea population, accounting for a remarkable 85.4 %. Furthermore, our results from inhibition experiments, RT-qPCR, and metagenome-assembled genome (MAG) analysis highlighted the active role of Ca. Methanoperedens GTF50 in the GTF zone. This microorganism could independently mediate AOM process through the intriguing "reverse methanogenesis" pathway. Considering the similarity in geochemical conditions across different paddy fields, it is likely that Ca. Methanoperedens-mediated AOM is prevalent in the GTF zones.


Assuntos
Água Subterrânea , Metano , Oryza , Oxirredução , Metano/metabolismo , Água Subterrânea/química , Água Subterrânea/microbiologia , Anaerobiose , Archaea/genética , Archaea/metabolismo
14.
Chemosphere ; 350: 141038, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38147928

RESUMO

Wastewater containing selenium (Se) and soil contaminated by mercury (Hg) are two environmental problems, but they are rarely considered for synergistic treatment. In this work, anaerobic granular sludge (AnGS) was used to address both of the aforementioned issues simultaneously. The performance and mechanisms of Se(IV) removal from wastewater and Hg(II) immobilization in soil were investigated using various technologies. The results of the reactor operation indicated that the AnGS efficiently removed Se from wastewater, with a removal rate of 99.94 ± 0.05%. The microbial communities in the AnGS could rapidly reduce Se(IV) to Se0 nanoparticles (SeNPs). However, the AnGS lost the ability to reduce Se(IV) once the Se0 content reached the saturation value of 5.68 g Se/L. The excess sludge of Se0-rich AnGS was applied to remediate soil contaminated with Hg(II). The Se0-rich AnGS largely decreased the percentage of soil Hg in the mobile, extractable phase, with up to 99.1 ± 0.3% immobilization. Soil Hg(II) and Hg0 can react with Se (-II) and Se0, respectively, to form HgSe. The formation of inert HgSe was an important pathway for immobilizing Hg. Subsequently, the pot experiments indicated that soil remediation using Se0-rich AnGS significantly decreased the Hg content in pea plants. Especially, the content of Hg decreased from 555 ± 100 to 24 ± 3 µg/kg in roots after remediation. In summary, AnGS is an efficient and cost-effective material for synergistically treating Se-contaminated wastewater and Hg-contaminated soil.


Assuntos
Mercúrio , Selênio , Mercúrio/metabolismo , Selênio/metabolismo , Esgotos , Águas Residuárias , Anaerobiose , Solo
15.
Water Res ; 253: 121334, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38382293

RESUMO

Ubiquitous presence of the extremely persistent pollutants, per- and polyfluoroalkyl substances, is drawing ever-increasing concerns for their high eco-environmental risks which, however, are insufficiently considered based on the assembly characteristics of those amphiphilic molecules in environment. This study investigated the re-organization and self-assembly of perfluorooctane sulfonate (PFOS) and macronutrient molecules from rhizospheric organic (RhO) matter induced with a common operation of aeration. Atomic force microscopy (AFM) with infrared spectroscopy (IR)-mapping clearly showed that, after aeration and stabilization, RhO nanocapsules (∼ 1000 nm or smaller) with a core of PFOS-protein complexes coated by "lipid-carbohydrate" layers were observed whereas the capsule structure with a lipid core surrounded by "protein-carbohydrate-protein" multilayers was obtained in the absence of PFOS. It is aeration that exerted the disassociation of pristine RhO components, after which the environmental concentration PFOS restructured the self-assembly structure in a conspicuous "disorder-to-order" transition. AFM IR-mapping analysis of faeces combined with quantification of component uptake denoted the decreased ingestion and utilization of both PFOS and proteins compared with lipids and carbohydrates when Daphnia magna were fed with RhO nanocapsules. RhO nanocapsules acted as double-edged swords via simultaneously impeding the bioaccessibility of hazardous PFOS molecules and macronutrient proteins; and the latter might be more significant, which caused a malnutrition status within merely 48 h. Elucidating the assembly structure of natural organic matter and environmental concentration PFOS, the finding of this work could be a crucial supplementation to the high-dose-dependent eco-effect investigations on PFOS.

16.
Water Res ; 253: 121311, 2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38367382

RESUMO

The antagonistic effects of mercury (Hg) and selenium (Se) have been extensively studied in higher animals and plants. In this study, the microbial antagonistic effects of Hg and Se were utilized for wastewater treatment. We developed and optimized a new granular sludge approach to efficiently remove Hg(II) and Se(IV) from wastewater. Under anaerobic-oxic-anaerobic (AOA) conditions, the removal rates of Hg(II) and Se(IV) reached up to 99.91±0.07 % and 97.7 ± 0.8 %, respectively. The wastewater Hg(II) was mostly (97.43±0.01 %) converted to an inert mineral called tiemannite (HgSe) in the sludge, and no methylmercury (MeHg) was detected. The HgSe in sludge is less toxic, with almost no risk of secondary release, and it can be recovered with high purity. An inhibition experiment of mercury reduction and the high expression of the mer operon indicated that most Hg(II) (∼71 %) was first reduced to Hg0, and then Hg0 reacted with Se0 to synthesize HgSe. Metagenomic results showed that the final sludge (day 182) was dominated by two unclassified bacteria in the orders Rhodospirillales (27.7 %) and Xanthomonadales (6.3 %). Their metagenome-assembled genomes (MAGs) were recovered, suggesting that both of them can reduce Hg(II) and Se(IV). Metatranscriptomic analyses indicate that they can independently and cooperatively synthesize HgSe. In summary, granular sludge under AOA conditions is an efficient method for removing and recovering Hg from wastewater. The microbial transformation of Hg2+to Hg0 to HgSe may occur widely in both engineering and natural ecosystems.


Assuntos
Mercúrio , Compostos de Metilmercúrio , Selênio , Purificação da Água , Animais , Selênio/metabolismo , Esgotos/microbiologia , Águas Residuárias , Ecossistema , Purificação da Água/métodos
17.
J Hazard Mater ; 478: 135515, 2024 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-39178777

RESUMO

The behavior and fate of PFOS (perfluorooctanesulfonate) in the aquatic environment have received great attention due to its high toxicity and persistence. The nanoscale supramolecular mechanisms of interaction between PFOS and ubiquitous EPS (exopolymers) remain unclear though EPS have been widely-known to influence the bioavailability of PFOS. Typically, the exposure patterns of PFOS in aquatic animals changed with the EPS-PFOS interaction are not fully understood. This study hypothesized that PFOS exposure and accumulation pathways depended on the PFOS-EPS interactive assembly behavior and animal species. Two model animals, zebrafish and chironomid larvae, with different feeding habitats were chosen for the exposure and accumulation tests at the environmental concentrations of PFOS in the absence and presence of EPS. It was found that PFOS triggered the self-assembly of EPS to form large aggregates which significantly trapped PFOS. PFOS accumulation was significantly promoted in zebrafish but drastically reduced in chironomid larvae because of the nanoscale interactive assembly between EPS and PFOS. The decreased dermal uptake but increased oral uptake of PFOS by zebrafish with large mouthpart size could be ascribed to the increased ingestion of PFOS-enriched EPS aggregates as food. For the chironomid larvae with small mouthpart size, the PFOS-EPS assemblies reduced the dermal, oral and intestinal uptake of PFOS. The nano-visualization evidences confirmed that the PFOS-enriched EPS-PFOS assemblies blocked PFOS penetration through skin of both animals. These findings provide novel knowledge about the ecological risk of PFOS in aquatic environments.


Assuntos
Ácidos Alcanossulfônicos , Chironomidae , Fluorocarbonos , Larva , Poluentes Químicos da Água , Peixe-Zebra , Animais , Ácidos Alcanossulfônicos/metabolismo , Ácidos Alcanossulfônicos/toxicidade , Fluorocarbonos/metabolismo , Fluorocarbonos/toxicidade , Chironomidae/metabolismo , Chironomidae/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Poluentes Químicos da Água/metabolismo , Larva/metabolismo , Larva/efeitos dos fármacos , Ecossistema
18.
J Hazard Mater ; 465: 133170, 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38064942

RESUMO

More single-use plastics are accumulating in the environment, and likewise biodegradable plastics (BPs), which are being vigorously promoted, cannot escape the fate. Currently, studies on the actual degradation of BPs in open-air and freshwaters are underrepresented despite they are potentially headmost leakage and contamination sites for disposable BPs. Herein, we compared the degradation behavior of six BP materials and non-degradable polypropylene (PP) plastics over a 1-year in situ suspension in the high-humidity air, a eutrophic river, and an oligotrophic lake. Moreover, a 3-months laboratory incubation was performed to detect the release of dissolved organic carbon (DOC) from BPs. In both air and freshwaters, poly(p-dioxanone) (PPDO) degraded significantly while PP and polylactic acid (PLA) showed no signs of degradation. The average degradation rates of three poly(butylene adipate-co-terephthalate) (PBAT)-based films varied: 100% in river, 55% in lake, and 10% in air. In addition to PLA, surface chemical groups, hydrophilicity, and thermal stability of BPs changed, and microplastics were found on their surfaces. Correspondingly, BPs with faster degradation rates released relatively higher amounts of DOC. Environmental microbial and chemical characteristics may contribute to differences in BP degradation besides polymer specificity. Altogether, our results indicate the need for appropriate monitoring of BPs.

19.
Sci Total Environ ; 914: 169976, 2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38199380

RESUMO

The ubiquitous transparent exopolymer particles (TEPs) are an important organic carbon pool and an ideal microhabitat for bacteria in aquatic environments. They play a crucial role in the global carbon cycle. Organic matter transformation and carbon turnover in TEPs strongly depend on the assembly of their associated bacterial communities and enzyme activity. However, the mechanisms of bacterial community assembly and their potential effects on the organic carbon cycle in TEPs are still unclear. In this study, we comparatively explored the community assembly of TEP-associated bacteria and bacterioplankton from surface freshwater using metagenomics. It was found that the bacterial community assembly in TEPs followed a minority-dominant rule and was governed by homogeneous selection. Pseudomonadota and Actinomycetota, which are responsible for polysaccharide degradation, serve as taxon-specific biomarkers among the abundant and diverse bacteria in TEPs. The network of TEP-associated bacteria displayed stronger robustness than that of bacterioplankton. Bin 76 (majorly Acinetobacter) was the overwhelmingly dominant taxa in TEPs, whereas there was no clearly dominant taxa in TEP-free water. Exoenzyme analysis showed that 64 out of 71 identified polysaccharide hydrolases were markedly linked with the dominant bin 76 in TEPs, while no such linkage was observed for bacterioplankton. Generally, Acinetobacter, which is capable of utilizing polysaccharides, is preferred to be assembled in TEPs together with high polysaccharide hydrolase activity. This may significantly accelerate the turnover of organic carbon in the giant global TEP pool. These findings are important for a deep understanding of the carbon cycle in water.


Assuntos
Matriz Extracelular de Substâncias Poliméricas , Água , Matriz Extracelular de Substâncias Poliméricas/metabolismo , Água/metabolismo , Polissacarídeos/metabolismo , Bactérias/metabolismo , Carbono/metabolismo
20.
Adv Sci (Weinh) ; 11(31): e2403984, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38896794

RESUMO

Capacitance spectroscopy techniques have been widely utilized to evaluate the defect properties in perovskites, which contribute to the efficiency and operation stability development for perovskite solar cells (PSCs). Yet the interplay between the charge transporting layer (CTL) and the perovskite on the capacitance spectroscopy results is still unclear. Here, they show that a pseudo-trap-state capacitance signal is generated in thermal admittance spectroscopy (TAS) due to the enhanced resistance capacitance (RC) coupling caused by the carrier freeze-out of the CTL in PSCs, which could be discerned from the actual defect-induced trap state capacitance signal by tuning the series resistance of PSCs. By eliminating the RC coupling shielding effect on the defect-induced capacitance spectroscopy, it is obtain the actual defect density which is 4-folds lower than the pseudo-trap density, and the spatial distribution of defects in PSCs which reveals that the commonly adopted interface passivators can passivate the defects about 60 nm away from the decorated surface. It is further revealed that phenethylammonium ions (PEA+) possess a better passivation capability over octylammonium ions (OA+) due to the deeper passivation depth for PEA+ on the surface defects in perovskite films.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA