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High-redox-capacity solid contact based on ferrocenyl self-assembled monolayer functionalized macroporous gold for an all-solid-state carbonate-selective electrode
No full textSolid-contact ion-selective electrodes (ISEs) are a promising tool for direct detection of CO32- activity/concen-tration in seawater. Herein, a stable solid-contact CO32--ISE was fabricated based on ferrocenyl self-assembled monolayer (SAM) functionalized macroporous gold (m-PG). Instead of the commonly used planar electrode, the m-PG film, prepared by using an electrochemical self-templating method involving the gold electrodeposition and hydrogen bubbling generation, is used as the conductive substrate. The redox capacity of the ferrocenyl SAM on the m-PG film is much larger than that on the planar Au electrode, due to the high surface area and good conductivity of m-PG. The solid-contact CO32--ISE based on ferrocenyl SAM modified m-PG shows a Nernstian potential response in the activity range from 2.6 x 10-5 to 5.3 x 10-4 M with a slope of 28.3 +/- 0.4 mV/dec and a detection limit of 1.1 x 10-5 M. The proposed electrode also exhibits a good electrode-to-electrode reproduc-ibility with a standard variation of the standard potential (E0) of 1.5 mV (n = 7), an improved potential stability and a long lifetime up to at least 120 days. The strategy for electrode substrate transformation from planar gold substrate to porous gold substrate provides an alternative way to improve the redox capacities of ferrocenyl SAMs for preparing the stable and reliable solid-contact ISEs
High-redox-capacity solid contact based on ferrocenyl self-assembled monolayer functionalized macroporous gold for an all-solid-state carbonate-selective electrode
No full textSolid-contact ion-selective electrodes (ISEs) are a promising tool for direct detection of CO32- activity/concen-tration in seawater. Herein, a stable solid-contact CO32--ISE was fabricated based on ferrocenyl self-assembled monolayer (SAM) functionalized macroporous gold (m-PG). Instead of the commonly used planar electrode, the m-PG film, prepared by using an electrochemical self-templating method involving the gold electrodeposition and hydrogen bubbling generation, is used as the conductive substrate. The redox capacity of the ferrocenyl SAM on the m-PG film is much larger than that on the planar Au electrode, due to the high surface area and good conductivity of m-PG. The solid-contact CO32--ISE based on ferrocenyl SAM modified m-PG shows a Nernstian potential response in the activity range from 2.6 x 10-5 to 5.3 x 10-4 M with a slope of 28.3 +/- 0.4 mV/dec and a detection limit of 1.1 x 10-5 M. The proposed electrode also exhibits a good electrode-to-electrode reproduc-ibility with a standard variation of the standard potential (E0) of 1.5 mV (n = 7), an improved potential stability and a long lifetime up to at least 120 days. The strategy for electrode substrate transformation from planar gold substrate to porous gold substrate provides an alternative way to improve the redox capacities of ferrocenyl SAMs for preparing the stable and reliable solid-contact ISEs
Nonylphenol displays immunotoxicity by triggering hemocyte extracellular traps in Manila clam via ROS burst, ERK pathway and glycolysis
No full textNonylphenol (NP), an endocrine disruptor, has been demonstrated to be a harmful environmental contaminant and toxic to organisms. In this study, to address concerns regarding the immunotoxicity of NP, we treated clam Ruditapes philippinarum hemocytes with NP in vitro and explored the underlying mechanisms of NP-induced extracellular traps (ETs). NP could induce the formation of hemocytes ETs in a dose-dependent manner. Transcriptomics analysis revealed changes of signaling pathway involved in immunity and energy metabolism in hemocytes after NP stimulation. In this process, both reactive oxygen species (ROS) and myeloperoxidase (MPO) were up-regulated. Moreover, mitogen-activated protein kinase (MAPK) signaling pathway was proved to be activated in the formation of NP-induced ETs, manifested as enhanced phosphorylation of extracellular signal-regulated kinase (ERK) but not p38 or c-Jun N-terminal kinase (JNK). In the presence of U0126, an ERK phosphorylation inhibitor, the NP-induced expression of NADPH oxidase enzyme (NOX) was significantly decreased, which further alleviated the ROS production and ultimately limited the release of ETs. NP exposure increased glucose uptake, along with enhanced activities of glycolysis-related enzymes such as hexokinase (HK) and pyruvate kinase (PK). After inhibiting glycolysis by the inhibitor 2-DG, the formation of NP-induced ETs was significantly suppressed. ERK could regulate mTOR signaling and the PI3K/AKT pathway, potentially directing ETs formation by orchestrating the glycolysis through the activation of key transcription factors c-Myc and HIF-1 alpha. Collectively, the results preliminary confirm that the ERK-NOX-ROS axis and glycolysis are involved in NP-induced ETs formation, contributing to the cellular immunotoxicity in clam
The effects of climate warming and exogenous nitrogen input on soil N2O emissions from mangroves
No full textThe paucity of studies on nitrous oxide (N2O) dynamics with rising temperatures and nitrogen (N)-based eutrophication makes it challenging to evaluate the role of mangroves in mitigating climate change. Here, a 3year mesocosm experiment was conducted to investigate the effects of climate warming (+3 degrees C) and excessive N input (25 mg N L- 1) on soil N2O emissions from two mangroves (Avicennia marina and Bruguiera gymnorrhiza). We found that warming and N input alone significantly increased soil N2O emissions from both mangroves, while the interactive effects of warming and N input on soil N2O emissions were affected by mangrove species. Warming mitigated the positive effect of N input on soil N2O emissions from A. marina; and amplified the effect of N input on soil N2O emissions from B. gymnorrhiza, suggesting that the response of soil N2O emissions to these global change factors is species-dependent. Stable isotopic signature analysis revealed that both warming and N input significantly increased the relative contribution of nitrification to N2O emissions from A. marina; whereas N input, rather than warming, significantly changed the relative contribution of nitrification in B. gymnorrhiza. This could be attributed to the differential changes in soil environmental conditions, plant growth and the microbial structure of the two mangroves. Overall, this study highlights the role of mangrove species in modifying the effects of warming and N input on soil N2O emissions, which should be considered when accurately projecting N2O emissions from mangroves. Furthermore, considering the low N2O emissions from background sediments and the common N limitation across mangroves, our findings suggest that climate warming and exogenous N input may lead to a surge of N2O emissions from mangroves, especially those that are seriously affected by human activities
G-Quadruplex Dimer/Exonuclease I Assisted Signal Amplification Strategy for Rapid Determination of Aflatoxin B1 Using a Paper Chip
No full textIn this work, a tetrahedral DNA nanostructure (TDN) functionalized rotational paper-based analytical device (RPAD) was constructed for rapid and highly sensitive detection of aflatoxin B1 (AFB1) using exonuclease I (Exo I ) and G-quadruplex (G4) dimer. Herein, a single-stranded DNA, containing both of the G4 dimer sequence and AFB1 recognition sequence, was used as the recognition probe (G4 dimer probe). TDN was used to precisely regulate the orientation and distribution density of G4 dimer probe to improve the recognition efficiency of the system. Exo I as a single stranded DNA specific nuclease was introduced for effective amplification of the detection signal. G4 dimer was employed to enhance the fluorescence signal of thioflavin T (ThT). In the absence of AFB1, the G4 dimer structure of G4 dimer probe could specifically bind with ThT to generate dramatic fluorescence enhancement. However, in the presence of AFB1, AFB1 could specifically bind with G4 dimer probe, resulting in the dissociation of G4 dimer probe from TDN and further be digested by Exo I . At the same time, the released AFB1 could bind to G4 dimer probe on the TDN again by this way to generate signal amplification. After this cycle, the amount of aptamer on the TDN was decreased, accompanied by the reduction of G4 dimer on TDN. In this case, the fluorescence intensity of the system was reduced. The designed RPAD showed a good linear response in AFB1 concentration range of 0.0001-500 ng/mL and the limit of detection was 0.1 pg/mL. Moreover, the proposed strategy was successfully applied to detection of AFB1 in peanut and wine. The developed TDN/G4 dimer/Exo I strategy improved the specificity and sensitivity of the system significantly
Spatio-seasonal variations in functional trait composition and diversity patterns of marine fish communities in coastal waters
No full textDespite the consensus that the distribution of functional traits within a community provides insights into community assembly and maintenance mechanisms, few studies have explored spatio-seasonal variations in the functional patterns of marine fish communities. Seven functional traits within the context of 2 distinct groups-habitat use and trophic niche-were selected to assess functional richness (FRic), functional evenness (FEve), and functional dispersion (FDis) across various spatio-seasonal scales. Community-weighted mean redundancy analysis (CWM-RDA) was used to identify the impact of environmental factors on dominant traits. We found seasonal and spatial variations in dominant traits of the fish community, notably influenced by the latitudinal-depth gradient (from shallower stations in the north to deeper stations in the south), east-west (longitudinal) dynamics, and temperature gradient. Latitude was negatively correlated with the CWM values of most functional trait categories. FRic showed more pronounced seasonal variations than other indices, with higher values observed in autumn. Fish assemblages displayed more similarity in functional traits in winter than in other seasons, with lower FRic, higher FEve, and lower FDis. Overall, our findings illustrate that fish assemblages undergo continuous formation and dissolution across different seasons and zones, resulting in various forms of functional diversity patterns
Long-term pollution status of microplastics in sediment of a typical mariculture area
No full textMicroplastics (MPs) are pervasive in various environmental media, posing a significant global issue. However, long-term data on marine MPs pollution trends are limited. This study investigates sediment samples from six stations in Sishili Bay, Yellow Sea, collected in 2015, 2018, and 2021, an area impacted by industrial, maricultural, and tourism activities. Findings reveal an annual increase in MPs abundance, with mean concentrations of 92.60 +/- 23.93 items/kg.dw in 2015, 146.18 +/- 14.80 items/kg.dw in 2018, and 203.21 +/- 20.31 items/kg.dw in 2021. MPs distribution is spatially uniform, showing no significant seasonal changes, attributed to the bay's semi-enclosed nature. Predominant MPs are fibers (>70 %) and transparent particles (>35 %), with most particles <1000 mu m. PET and Rayon are the main polymers identified. The study emphasizes the escalating MPs pollution in the mariculture area, highlighting the urgent need for targeted pollution control and mitigation strategies
Phylogenetic distribution and characterization of conserved C-di-GMP metabolizing proteins in filamentous cyanobacterium Arthrospira
No full textCyclic diguanosine monophosphate (c-di-GMP) is a second messenger in bacteria that regulates multiple biological functions, including biofilm formation, virulence, and intercellular communication. However, c-di-GMP signaling is virtually unknown in economically important filamentous cyanobacteria, Arthrospira. In this study, we predicted 31 genes encoding GGDEF-domain proteins from A. platensis NIES39 as potential diguanylate cyclases (DGCs). Phylogenetic distribution analysis showed five genes (RS09460, RS04865, RS26155, M01840, and E02220) with highly conserved distribution across 25 Arthrospira strains. Adc1 encoded by RS09460 was further characterized as a typical DGC. By establishing the genetic transformation system of Arthrospira, we demonstrated that the overexpression of Adc1 promoted the production of extracellular polymeric substances (EPS), which in turn caused the aggregation of filaments. We also confirmed that RS04865 and RS26155 may encode active DGCs, while enzymatic activity assays showed that proteins encoded by M01840 and E02220 have phosphodiesterase (PDE) activity. Meta-analysis revealed that the expression profiles of RS09460 and RS04865 were unaffected under 31 conditions, suggesting that they may function as conserved genes in maintaining the basal level of c-di-GMP in Arthrospira. In summary, this report will provide the basis for further studies of c-diGMP signal in Arthrospira
H<sub>2</sub>S scavenger as a broad-spectrum strategy to deplete bacteria-derived H<sub>2</sub>S for antibacterial sensitization
No full textBacteria-derived H2S plays multifunctional protective roles against antibiotics insult, and the H2S biogenesis pathway is emerging as a viable target for the antibacterial adjuvant design. However, the development of a pan-inhibitor against H2S-synthesizing enzymes is challenging and underdeveloped. Herein, we propose an alternative strategy to downregulate the H2S levels in H2S-producing bacteria, which depletes the bacteria-derived H2S chemically by H2S scavengers without acting on the synthesizing enzymes. After the screening of chemically diversified scaffolds and a structural optimization campaign, a potent and specific H2S scavenger is successfully identified, which displays efficient H2S depletion in several H2S-producing bacteria, potentiates both bactericidal agents and photodynamic therapy, enhances the bacterial clearance of macrophages and polymorphonuclear neutrophils, disrupts the formation of bacterial biofilm and increases the sensitivity of bacterial persister cells to antibiotics. Most importantly, such an H2S scavenger exhibits sensitizing effects with gentamicin in Pseudomonas aeruginosa -infected pneumonia and skin wound female mouse models. In aggregate, our results not only provide an effective strategy to deplete bacteria-derived H2S and establish the H2S biogenesis pathway as a viable target for persisters and drug-resistant bacteria, but also deliver a promising antibacterial adjuvant for potential clinical translation.
Bacteria-derived H2S functions as a universal defense against antibiotics challenge. Here, Ji et al developed a broad-spectrum H2S scavenger that efficiently removes endogenous H2S in several bacteria, disrupts biofilm formation and sensitizes persister cells to antibiotic-mediated killing in vitro and in vivo
The Sources and Atmospheric Processes of Strong Light-Absorbing Components in Water Soluble Brown Carbon: Insights From a Multi-Proxy Study of PM<sub>2.5</sub> in 10 Chinese Cities
No full textHumic-like substances (HULIS) are significant contributor to the light absorption of water-soluble brown carbon (WSBrC), which contains certain strong light-absorbing chemical components that are not well understood, impeding the assessment of WSBrC's climate impact. China as the hotspot regions with high loading of WSBrC characterized by high light-absorbing capacity, here, we investigated the sources and atmospheric processes (delta C-13-Delta C-14), molecular composition (Fourier transform ion cyclotron resonance mass spectrometry), and light absorption properties (UV spectrophotometry) of HULIS in PM2.5 from 10 Chinese cities. HULIS-C was major contributor to the light absorption coefficient (70.5 +/- 6.6%) of WSBrC at 365 nm, which was more enriched with fossil sources (48.0 +/- 9.0% vs. 30.3 +/- 13.9%) but depleted in C-13 (delta C-13: -25.6 +/- 0.9 parts per thousand vs. -22.4 +/- 1.0 parts per thousand) relative to non-HULIS-C. This suggests that the fossil components in HULIS are more recalcitrant to oxidative aging and exhibit higher light-absorbing capacity, while the non-fossil organic carbon is more likely to be oxidatively bleached into small, colorless, and highly polar molecules (i.e., non-HULIS). Aromatic components are the major strong light-absorbing fossil components in HULIS, dominantly originating from coal combustion (>77%). Non-negative matrix factorization model showed that aromatic molecules from coal combustion have higher molecular weight and lower oxidation levels than biomass burning, potentially making them to be photo-recalcitrant compounds. Our finding that coal combustion-derived BrC maybe more persistent in the atmosphere and has greater long-term impact on climate than BrC derived from biomass burning is an important consideration in climate models and mitigation policies