Quantitative detecting low concentration polystyrene nanoplastics in aquatic environments via an Ag/Nb2CTx (MXene) SERS substrate.

In this study, the plasmonic Ag nanoparticles (Ag NPs) were uniformly anchored on the high conductivity Nb2CTx (MXene) nanosheets to construct an Ag/Nb2CTx substrate for surface-enhanced Raman spectroscopy (SERS) detection of polystyrene (PS) nanoplastics. The KI addition (0.15 mol/L), the volume ratio between substrate colloid and nanoplastic suspension (2:1), and the mass ratio of Nb2CTx in substrate (14%) on SERS performance were optimized. The EM hot spots of Ag/Nb2CTx are significantly enlarged and enhanced, elucidated by FDFD simulation. Then, the linear relationship between the PS nanoplastics concentration with three different sizes (50, 300, and 500 nm) and the SERS intensity was obtained (R2 > 0.976), wherein, the detection limit was as low as 10-4 mg/mL for PS nanoplastic. Owing to the fingerprint feature, the Ag/Nb2CTx-14% substrate successfully discerns the mixtures from two-component nanoplastics. Meanwhile, it exhibits excellent stability of PS nanoplastics on different detection sites. The recovery rates of PS nanoplastics with different sizes in lake water ranged from 94.74% to 107.29%, with the relative standard deviation (RSD) ranging from 2.88% to 8.30%. Based on this method, the expanded polystyrene (EPS) decomposition behavior was evaluated, and the PS concentrations in four water environments were analyzed. This work will pave the way for the accurate quantitative detection of low concentration of nanoplastics in aquatic environments.

Environmentally relevant concentrations of 2,3,7,8-TCDD induced inhibition of multicellular alternative splicing and transcriptional dysregulation.

Alternative splicing (AS), found in approximately 95 % of human genes, significantly amplifies protein diversity and is implicated in disease pathogenesis when dysregulated. However, the precise involvement of AS in the toxic mechanisms induced by TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) remains incompletely elucidated. This study conducted a thorough global AS analysis in six human cell lines following TCDD exposure. Our findings revealed that environmentally relevant concentration (0.1 nM) of TCDD significantly suppressed AS events in all cell types, notably inhibiting diverse splicing events and reducing transcript diversity, potentially attributed to modifications in the splicing patterns of the inhibitory factor family, particularly hnRNP. And we identified 151 genes with substantial AS alterations shared among these cell types, particularly enriched in immune and metabolic pathways. Moreover, TCDD induced cell-specific changes in splicing patterns and transcript levels, with increased sensitivity notably in THP-1 monocyte, potentially linked to aberrant expression of pivotal genes within the spliceosome pathway (DDX5, EFTUD2, PUF60, RBM25, SRSF1, and CRNKL1). This study extends our understanding of disrupted alternative splicing and its relation to the multisystem toxicity of TCDD. It sheds light on how environmental toxins affect post-transcriptional regulatory processes, offering a fresh perspective for toxicology and disease etiology investigations.

In Situ Activation of Azaarenes and Terminal Alkynes to Construct Bridged Polycyclic Compounds Containing Isoquinolinones.

A copper-catalyzed [4+2] cyclization reaction of isoquinolines and alkynes is developed for the one-step construction of isoquinolinone derivatives with multisubstituted bridging rings. The unique feature of this three-component tandem cyclization reaction is the functionalization of the C1, N2, C3, and C4 positions of 3-haloisoquinolines via the construction of new C-N, C═O, and C-C bonds. This dearomatization strategy for the synthesis of structurally complex isoquinolinone-bridged cyclic compounds offers good chemoselectivity, broad functional group compatibility, greenness, and high step economy.

Di-2-ethylhexyl phthalate disrupts hepatic lipid metabolism in obese mice by activating the LXR/SREBP-1c and PPAR-α signaling pathways.

Di-2-ethylhexyl phthalate (DEHP), a widely utilized plasticizer, has been described as a potential obesogen based on in vivo disruption of hepatic lipid homeostasis and in vitro promotion of lipid accumulation. However, limited literature exists regarding the specific ramifications of DEHP exposure on obese individuals, and the precise mechanisms underlying the adverse effects of DEHP exposure remain unclear. This study aimed to assess the impact of DEHP on hepatic lipid metabolism in obese mice by comparing them to normal mice. Following a 10-week DEHP exposure period, the obese mice exhibited higher blood lipid levels, more severe hepatic steatosis, and more infiltrations of inflammatory cells in liver tissue than normal mice. Interestingly, the body weight of the mice exhibited no significant alteration. In addition, transcriptomic analyses revealed that both lipogenesis and fatty acid oxidation contributed to hepatic lipid metabolism dysregulation following DEHP exposure. More specifically, alterations in the transcription of genes associated with hepatic lipid metabolism were linked to the different responses to DEHP exposure observed in normal and obese mice. Additionally, the outcomes of in vitro experiments validated the in vivo findings and demonstrated that DEHP exposure could modify hepatic lipid metabolism in normal mice by activating the LXR/SREBP-1c signaling pathway to promote lipogenesis. At the same time, DEHP exposure led to inhibition of the Camkkß/AMPK pathway to suppress ß-fatty acid oxidation. Conversely, in obese mice, DEHP exposure was found to be associated with the stimulation of both lipogenesis and fatty acid oxidation via activation of the LXR/SREBP-1c and PPAR-α signaling pathways, respectively. The findings presented in this study first elucidate the contrasting mechanisms underlying DEHP-induced liver damage in obese and normal mice, thereby offering valuable insights into the pathogenesis of DEHP-induced liver damage in individuals with obesity.

Inner-Wall Coated Nanopipette Microextraction for Quantitative Analysis of Per- and Polyfluoroalkyl Substances in Single Cells Using Mass Spectrometry.

Per- and polyfluoroalkyl substances (PFASs) are a series of organic pollutants with potential cytotoxicity and biotoxicity. Accurate and sensitive detection of trace PFASs in single cells can provide insights into investigating their cytotoxicity, carcinogenicity, and mutagenicity. Here we report the development of an inner-wall coated nanopipette microextraction coupled with induced nanoelectrospray ionization mass spectrometry (InESI-MS) method and its application for rapid, sensitive, and accurate analysis of trace PFASs in single cells. A specially designed inner-wall coated nanopipette was prepared for sampling of the cytoplasm from a single cell, and the trace PFASs in the cytoplasm were selectively enriched into the coating via reversed-phase adsorption, ion bonding adsorption, and π-π interaction mechanisms. After the extraction, the cytoplasm was removed, and the enriched PFASs were then desorbed into some organic solvent, applying an alternating current (AC) voltage to the inner-wall coated nanopipette for InESI-MS analysis. The inner-wall coated nanopipette showed an exhaustive extraction to the trace PFASs in one single cell, and thus, the mass of each target analyte in the cytoplasm can be calculated via an internal standard calibration curve method, avoiding the measurement of ultrasmall volume cytoplasm for one single cell. By using the inner-wall coated nanopipette microextraction coupled with InESI-MS method, trace PFASs accumulated in the LO2 cells with pollutant exposure were successfully detected, and the accumulative behaviors and heterogeneities of PFASs in single cells were explored.

Fe, N, S co-doped carbon network derived from acetate-modified Fe-ZIF-8 for oxygen reduction reaction.

In this work, potassium acetate (KAc) was added during the synthesis of a Zn-Fe based metal-organic framework (Fe-ZIF-8) to increase the fixed amount of Fe while simultaneously enhancing the number of pores. Electrospinning was utilized to embed KAc-modified Fe-ZIF-8 (Fe-ZIF-8-Ac) into the polyacrylonitrile nanofiber mesh, to obtain a network composite (Fe@NC-Ac) with hierarchical porous structure. Fe@NC-Ac was co-pyrolyzed with thiourea, resulting in Fe, N, S co-doped carbon electrocatalyst. The electrochemical tests indicated that the prepared catalyst displayed relatively remarkable oxygen reduction reaction (ORR) catalytic activity, with an onset potential (Eonset) of 1.08 V (vs. reversible hydrogen electrode, RHE) and a half-wave potential (E1/2) of 0.94 V, both higher than those of the commercial Pt/C (Eonset = 0.95 V and E1/2 = 0.84 V), respectively. Assembled into Zn-air batteries, the optimized catalyst exhibited higher open circuit voltage (1.698 V) and peak power density (90 mW cm-2) than those of the commercial 20 wt% Pt/C (1.402 V and 80 mW cm-2), respectively. This work provided a straightforward manufacturing strategy for the design of hierarchical porous carbon-based ORR catalysts with desirable performance.

[Characteristics and Ecological Risk Assessment of Pharmaceutical Active Compounds in Guangdong Province].

Pharmaceutically active compounds(PhACs) have become a class of new pollutants in the environment after extensive production and use of PhACs in China. To investigate the pollution characteristics of PhACs in Guangdong Province, raw sewage was collected from 186 sewage treatment plants in 21 cities, including 178 townships and administrative districts in Guangdong Province. The pollution levels of ten typical PhACs in influent water of sewage treatment plants were analyzed using automatic solid phase extraction and high performance liquid chromatography-triple quadrupole mass spectrometry. The spatial distribution characteristics of PhACs in Guangdong Province were fully revealed, and the potential ecological risks of PhACs were evaluated. The results showed that PhACs were detected in all wastewater plants, and the mass concentration of PhACs ranged from 21.00 to 9558.25 ng·L-1. Metoprolo, acetaminophen, bezafibrate, and caffeine were the main pollutants. In terms of spatial distribution, the average mass concentration of ΣPhACs in various regions of Guangdong Province was in the following order:Pearl River Delta>North Guangdong>East Guangdong≈West Guangdong. When the mass concentration of ΣPhACs was over 2500 ng·L-1 in the influent water of sewage treatment plants, the concentration of PhACs in effluent was estimated according to the sewage disposal technology. The ecological risk of PhACs was carried out based on the effluent. The results revealed that the ecological risk of PhACs was low in Guangdong Province, and the risk of bezafibrate was moderate in the cities of Shaoguan, Jiangmen, and Shenzhen. The highest ecological risk of ΣPhACs was located in Shaoguan.

Nanospray Laser-Induced Plasma Ionization Mass Spectrometry for Rapid and Sensitive Analysis of Polycyclic Aromatic Hydrocarbons and Halogenated Derivatives.

Polycyclic aromatic hydrocarbons (PAHs) and halogenated derivatives are a series of environmental pollutants with potential toxicity and health risks on biosystems and the ecosystem. Rapid and sensitive analysis of trace PAHs and halogenated PAHs in complex environmental samples is a challenging topic for analytical science. Here we report the development of a nanospray laser-induced plasma ionization MS method for rapid and sensitive analysis of trace PAHs and halogenated PAHs under ambient and open-air conditions. A nanospray tip was applied for loading samples and placed pointing to the MS inlet, being a nanospray emitter with the application of a high voltage. A beam of laser was focused to induce energetic plasma between the nanospray emitter and the MS inlet for ionization of PAHs and halogenated PAHs for mass spectrometric analysis. Meanwhile, an inner-wall naphthyl-coated nanospray emitter was developed and applied as a solid-phase microextraction (SPME) probe for highly selective enrichment of trace PAHs and halogenated PAHs in complex environmental samples, and some organic solvent was applied to desorb the analytes for nanospray laser-induced plasma ionization MS analysis. Satisfactory linearity for each target PAH and halogenated PAH was obtained, with correlation coefficient values (r) no less than 0.9917. The method showed extremely high sensitivity for analysis of trace PAHs and halogenated PAHs in water, with limits of detection (LODs) and quantification (LOQs) of 0.0001-0.02 and 0.0003-0.08 µg/L, respectively. By using the inner-wall naphthyl-coated nanospray laser-induced plasma ionization MS method, sensitive detection of trace PAHs and halogenated PAHs in real sewage and wastewater samples was successfully achieved.

Precise Lipidomics Decipher Circulating Ceramide and Sphingomyelin Cycle Associated with the Progression of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a long-term autoimmune condition that causes joint and surrounding tissue inflammation. Lipid mediators are involved in inflammation and deterioration of the joints. Despite attempts to discover effective drug targets to intervene with lipid metabolism in the disease, progress has been limited. In this study, precise lipidomic technology was employed to quantify a broad range of serum ceramides and sphingomyelin (SM) in a large cohort, revealing an association between the accumulation of circulating ceramides and disturbed ceramide/SM cycles during the progression of RA. In our investigation, we discovered that eight ceramides exhibited a positive correlation with the activity of RA, thereby enhancing the accuracy of RA diagnosis, particularly in patients with serum antibody-negative RA. Furthermore, the enzyme SM phosphodiesterase 3 (SMPD3) was found to disrupt the circulating SM cycle and accelerate the progression of RA. The activity of SMPD3 can be inhibited by methotrexate, resulting in decreased metabolic conversion of SM to ceramide. These findings suggest that targeting the SM cycle may provide a new therapeutic option for RA.

Perfluorooctanoic acid-induced metabolic disorder via enhancing metabolism of glutamine and fatty acids in human intestinal cells.

Intestinal cell metabolism plays an important role in intestine health. Perfluorooctanoic acid (PFOA) exposure could disorder intestinal cell metabolism. However, the mechanisms regarding how the three carbon sources interact under PFOA stress remined to be understood. The present study aimed to dissect the interconnections of glucose, glutamine, and fatty acids in PFOA-treated human colorectal cancer (DLD-1) cells using 13C metabolic flux analysis. The abundance of glycolysis and tricarboxylic acid (TCA) cycle metabolites was decreased in PFOA-treated cells except for succinate, whereas most of amino acids were more abundant. Beside serine and glycine, the levels of metabolites derived from 13C glucose were reduced in PFOA-treated cells, and the pentose phosphate pathway flux was 1.4-fold higher in PFOA-treated cells than in the controls. In reductive glutamine pathway, higher labeled enrichment of citrate, malate, fumarate, and succinate was observed for PFOA-treated cells. The contribution of glucose to fatty acid synthesis in PFOA-treated cells decreased while the contribution of glutamine to fatty acid synthesis increased. Additionally, synthesis of TCA intermediates from fatty acid ß-oxidation was promoted in PFOA-treated cells. All results suggested that metabolic remodeling could happen in intestinal cells exposed to PFOA, which was potentially related to PFOA toxicity relevant with the loss of glucose in biomass synthesis and energy metabolism.

Exploring the Accumulation Behavior and Heterogeneity of Perfluorooctanesulfonic Acid in Zebrafish Primary Organ Cells by Single-Cell Mass Cytometry.

Perfluorooctanesulfonic acid (PFOS) is a commonly found environmental pollutant with potential toxicity and health risks to biosystems and ecosystems. Study of the accumulation behavior and heterogeneity of PFOS in biological primary organ cells provides us significant insights to explore its cytotoxicity, carcinogenicity, and mutagenicity. Here a single-cell mass cytometry system was established for the high-throughput analysis of trace PFOS and the exploration of its accumulation behavior and heterogeneity in zebrafish primary organ cells. The single-cell mass cytometry system applied a ∼25 µm constant-inner-diameter capillary as the single-cell generation and transportation channel with an etched tip-end of 40 µm as the nanoelectrospray emitter for mass spectrometric analysis. The single-cell mass cytometry system showed satisfactory semiquantitative performance and sensitivity for analysis of PFOS in single cells, with a high detection throughput of ∼35 cells/min. Subsequently, the liver, intestine, heart, and brain from PFOS-exposed zebrafish (100 pg/µL, 28 days) were dissociated and prepared as cell suspensions, and the cell suspensions were introduced into the single-cell mass cytometry system for high-throughput analysis of PFOS in individual primary organ cells. Significant cellular accumulation heterogeneities were observed, with the highest content in liver cells, followed by intestine cells, then heart cells, and the lowest in brain cells. In addition, the dynamics of PFOS in the zebrafish liver, intestine, heart, and brain cells showed typical violin plot distributions and were well-described using a gamma (γ) function.

Infected wound repair with an ultrasound-enhanced nanozyme hydrogel scaffold.

Chronic diabetic wounds persistently face the threat of evolving into diabetic foot ulcers owing to severe hypoxia, high levels of reactive oxygen species (ROS), and a complex inflammatory microenvironment. To concurrently surmount these obstacles, we developed an all-round therapeutic strategy based on nanozymes that simultaneously scavenge ROS, generate O2 and regulate the immune system. First, we designed a dynamic covalent bond hybrid of a metal-organic coordination polymer as a synthesis template, obtaining high-density platinum nanoparticle assemblies (PNAs). This compact assembly of platinum nanoparticles not only effectively simulates antioxidant enzymes (CAT, POD) but also, under ultrasound (US), enhances electron polarization through the surface plasmon resonance effect, endowing it with the ability to induce GSH generation by effectively replicating the enzyme function of glutathione reductase (GR). PNAs, by mimicking the activity of CAT and POD, effectively catalyze hydrogen peroxide, alleviate hypoxia, and effectively generate GSH under ultrasound, further enhancing ROS scavenging. Notably, PNAs can regulate macrophage responses in the inflammatory microenvironment, circumventing the use of any additives. It was confirmed that PNAs can enhance cell proliferation and migration, promote neoangiogenesis IN VITRO, and accelerate the healing of infected diabetic wounds IN VIVO. We believe that an all-round therapeutic method based on PNA nanozymes could be a promising strategy for sustained diabetic wound healing.

Identification of lead-binding proteins as carriers and potential molecular targets associated with systolic blood pressure.

Lead (Pb) exposure is well recognized as a significant environmental factor associated with the high incidence of cardiovascular diseases. However, the carriers and molecular targets of Pb in human blood remain to be understood, especially for a real Pb exposure scenario. In this study, a total of 350 blood samples were collected from the smelting workers and systematically analyzed using metallomics and metalloproteomics approaches. The results showed that the majority of Pb (∼99.4%) could be presented in the blood cells. Pb in the cytoplasm of blood cells accounted for approximately 83.1% of the total blood Pb, with nearly half of Pb being bound to proteins. Pb-binding proteins in the blood of workers were identified as hemoglobin, catalase, haptoglobin, δ-aminolevulinic acid dehydratase, and peroxiredoxin-2. Multiple linear regression analysis demonstrated that higher levels of Pb bound to proteins (Mix-bound Pb and Protein-bound Pb) were positively associated with higher systolic blood pressure (p < 0.05). However, the association between blood lead level, Pb levels in the blood cells and systolic blood pressure was not observed (p > 0.05). This study suggested that Pb bound to proteins could be a suitable biomarker for indicating the potential risk of occupational hypertension.

Efflux transport proteins of Tetrahymena thermophila play important roles in resistance to perfluorooctane sulfonate exposure.

The biotoxicity of perfluorooctane sulfonate (PFOS) has been a concern. However, the effects of PFOS on Tetrahymena thermophila, a unicellular model organism, remain unclear. This study aimed to investigate the toxicity and detoxification mechanism of PFOS in this protozoan. PFOS did not show prominent toxic effects on T. thermophila. Cell viability of T. thermophila can be concentration-dependently increased by PFOS. PFOS also increased the stability of cell membranes and the activity of lysosomes. However, PFOS inhibited efflux transporter activities. Most of the PFOS amount remained in the culture medium during the culture periods. Only a low amount of PFOS was absorbed by cells, where PFOS molecules were mainly combined with membrane proteins. The expressions of four membrane protein genes involved in transporting xenobiotics were analyzed by real time-PCR. The gene abcg25 was significantly up-regulated. The growth of abcg25 gene knockout protozoans under PFOS treatment was slightly inhibited. However, the amount of PFOS adsorbed by the knockout protozoans showed no significant difference from the Wild-type protozoans. We concluded that the ABCG25 protein might play a key role in preventing PFOS from entering the cell or being exported from the cells to protect T. thermophila against PFOS. However, ABCG25 was not the only membrane protein able to bind with PFOS.

Recent progress in analytical strategies of arsenic-binding proteomes in living systems.

Arsenic (As) is one of the most concerning elements due to its high exposure risks to organisms and ecosystems. The interaction between arsenicals and proteins plays a pivotal role in inducing their biological effects on living systems, e.g., arsenicosis. In this review article, the recent advances in analytical techniques and methods of As-binding proteomes were well summarized and discussed, including chromatographic separation and purification, biotin-streptavidin pull-down probes, in situ imaging using novel fluorescent probes, and protein identification. These analytical technologies could provide a growing body of knowledge regarding the composition, level, and distribution of As-binding proteomes in both cells and biological samples, even at the organellar level. The perspectives on analysis of As-binding proteomes are also proposed, e.g., isolation and identification of minor proteins, in vivo targeted protein degradation (TPD) technologies, and spatial As-binding proteomics. The application and development of sensitive, accurate, and high-throughput methodologies of As-binding proteomics would enable us to address the key molecular mechanisms underlying the adverse health effects of arsenicals.

Key factors influencing pollution of heavy metals and phenolic compounds in mangrove sediments, South China.

Concentrations of heavy metals (HMs) and phenolic compounds with factors which potentially affected their spatial distribution were investigated in mangrove sediments, South China. Compared to Qi'ao, Futian sediments exhibited higher levels of Pb and nonylphenol (NP), but lower levels of Co and Ni. Seasonal variation showed higher concentrations of Pb, Cr, Co, NP and bisphenol A (BPA), while lower concentration of methylparaben (MP) in wet than dry season. Contaminant levels in sediments collected at different tidal heights showed insignificant variations, except for Zn and NP. MP was found negatively correlated with nearly all HMs and BPA, whereas the latter exhibited positive correlations with each other. Sedimentary total carbon, total nitrogen, C/N and N/P ratios were screened as the most influential factors affecting the distribution of these contaminants. Additionally, both salinity and total phosphate exhibited positive, while both pH and sedimentary particle size registered negative correlation, with one or more contaminants.

Altered generation pattern of reactive oxygen species triggering DNA and plasma membrane damages to human liver cells treated with arsenite.

Human exposure to arsenic via drinking water is one of globally concerned health issues. Oxidative stress is regarded as the denominator of arsenic-inducing toxicities. Therefore, to identify intracellular sources of reactive oxygen species (ROS) could be essential for addressing the detrimental effects of arsenite (iAsIII). In this study, the contributions of different pathways to ROS formation in iAsIII-treated human normal liver (L-02) cells were quantitatively assessed, and then concomitant oxidative impairs were evaluated using metabolomics and lipidomics approaches. Following iAsIII treatment, NADPH oxidase (NOX) activity and expression levels of p47phox and p67phox were upregulated, and NOX-derived ROS contributed to almost 60.0 % of the total ROS. Moreover, iAsIII also induced mitochondrial superoxide anion and impaired mitochondrial respiratory function of L-02 cells with a decreasing ATP production. The inhibition of NOX activity significantly rescued mitochondrial membrane potential in iAsIII-treated L-02 cells. Purine and glycerophospholipids metabolisms in L-02 cells were disrupted by iAsIII, which might be used to represent DNA and plasma membrane damages, respectively. Our study supported that NOX could be the primary pathway of ROS overproduction and revealed the potential mechanisms of iAsIII toxicity related to oxidative stress.

Development of a Repair Enzyme Fluorescent Probe to Reveal the Intracellular DNA Damage Induced by Benzo[a]pyrene in Living Cells.

Pollutant exposure causes a series of DNA damage in cells, resulting in the initiation and progression of diseases and even cancers. An investigation of the DNA damage induced by pollutants in living cells is significant to evaluate the cytotoxicity, genotoxicity, and carcinogenicity of environmental exposure, providing critical insight in the exploration of the etiologies of diseases. In this study, we develop a repair enzyme fluorescent probe to reveal the DNA damage caused by an environmental pollutant in living cells by single-cell fluorescent imaging of the most common base damage repair enzyme named human apurinic/apyrimidinic endonuclease 1 (APE1). The repair enzyme fluorescent probe is fabricated by conjugation of an APE1 high affinity DNA substrate on a ZnO2 nanoparticle surface to form a ZnO2@DNA nanoprobe. The ZnO2 nanoparticle serves as both a probe carrier and a cofactor supplier, releasing Zn2+ to activate APE1 generated by pollutant exposure. The AP-site in the DNA substrate of the fluorescent probe is cleaved by the activated APE1, releasing fluorophore and generating fluorescent signals to indicate the position and degree of APE1-related DNA base damage in living cells. Subsequently, the developed ZnO2@DNA fluorescent probe is applied to investigate the APE1-related DNA base damage induced by benzo[a]pyrene (BaP) in living human hepatocytes. Significant DNA base damage by BaP exposure is revealed, with a positive correlation of the damage degree with exposure time in 2-24 h and the concentration in 5-150 µM, respectively. The experimental results demonstrate that BaP has a significant effect on the AP-site damage, and the degree of DNA base damage is time-dependent and concentration-dependent.

Single-cell transcriptomic analysis reveals heterogeneity of the patterns of responsive genes and cell communications in liver cell populations of zebrafish exposed to polystyrene nanoplastics.

Nanoplastics (NPs) are a group of emerging environmental pollutants with potential toxicity and health risk on biosystem and ecosystem. Great efforts have been devoted to describing the uptake, distribution, accumulation, and toxicity of NPs at various aquatic organisms; however, the heterogeneous response patterns in zebrafish (Danio rerio) liver cell populations caused by NP exposure have not yet been clarified. Investigation of the heterogeneous response patterns in zebrafish liver cell populations after NPs exposure provides us significances to explore the NP cytotoxicity. In this article, the heterogeneous response patterns in zebrafish liver cell populations after polystyrene (PS)-NPs exposure were studied. Significantly increased content of malondialdehyde and decreased levels of catalase and glutathione were observed, indicating the oxidative damage of zebrafish liver induced by PS-NPs exposure. Afterwards, the liver tissues were enzymatically dissociated and used for single-cell transcriptomic (scRNA-seq) analysis. Nine cell types were identified based on unsupervised cell cluster analysis followed by their marker genes. Hepatocytes were the cell type most impacted by PS-NP exposure, and heterogeneous response patterns of male and female hepatocytes were observed. The PPAR signaling pathway was up-regulated in hepatocytes from both male and female zebrafish. Lipid metabolism-related functions were altered more notably in male-derived hepatocytes, while female-derived hepatocytes were more sensitive to estrogen stimulus and mitochondria. Macrophages and lymphocytes were also highly responsive cell types, with specific immune pathways activated to suggest immune disruption after exposure. Oxidation-reduction process and immune response were significantly altered in macrophages, and oxidation-reduction process, ATP synthesis, and DNA binding were most altered in lymphocytes. Our study not only integrates scRNA-seq with toxicology effects to identify highly sensitive and specific populations of responding cells, revealing highly specialized interactions between parenchymal and non-parenchymal cells and expanding our current understanding of PS-NPs toxicity, but also highlights the importance of cellular heterogeneity in environmental toxicology.

Characterization of metal resistance genes carried by waterborne free-living and particle-attached bacteria in the Pearl River Estuary.

Toxic metals can substantially change the bacterial community and functions thereof in aquatic environments. Herein, metal resistance genes (MRGs) are the core genetic foundation for microbial responses to the threats of toxic metals. In this study, waterborne bacteria collected from the Pearl River Estuary (PRE) were separated into the free-living bacteria (FLB) and particle-attached bacteria (PAB), and analyzed using metagenomic approaches. MRGs were ubiquitous in the PRE water and mainly related to Cu, Cr, Zn, Cd and Hg. The levels of PAB MRGs in the PRE water ranged from 8.11 × 109 to 9.93 × 1012 copies/kg, which were significantly higher than those of the FLB (p < 0.01). It could be attributed to a large bacterial population attached on the suspended particulate matters (SPMs), which was evidenced by a significant correlation between the PAB MRGs and 16S rRNA gene levels in the PRE water (p < 0.05). Moreover, the total levels of PAB MRGs were also significantly correlated with those of FLB MRGs in the PRE water. The spatial pattern of MRGs of both FLB and PAB exhibited a declining trend from the low reaches of the PR to the PRE and on to the coastal areas, which was closely related to metal pollution degree. MRGs likely carried by plasmids were also enriched on the SPMs with a range from to 3.85 × 108 to 3.08 × 1012 copies/kg. MRG profiles and taxonomic composition of the predicted MRG hosts were significantly different between the FLB and PAB in the PRE water. Our results suggested that FLB and PAB could behave differential response to heavy metals in the aquatic environments from the perspective of MRGs.