Environmentally relevant concentrations of microplastics modulated the immune response and swimming activity, and impaired the development of marine medaka Oryzias melastigma larvae.

Microplastics (MPs), due to their impacts on the ecosystem and their integration into the food web either through trophic transfer or ingestion directly from the ambient environment, are an emerging class of environmental contaminants posing a great threat to marine organisms. Most reports on the toxic effects of MPs exclusively focus on bioaccumulation, oxidative stress, pathological damage, and metabolic disturbance in fish. However, the collected information on fish immunity in response to MPs is poorly defined. In particular, little is known regarding mucosal immunity and the role of mucins. In this study, marine medaka (Oryzias melastigma) larvae were exposed to 6.0 µm beads of polystyrene microplastics (PS-MPs) at three environmentally relevant concentrations (102 particles/L, 104 particles/L, and 106 particles/L) for 14 days. The experiment was carried out to explore the developmental and behavioural indices, the transcriptional profiles of mucins, pro-inflammatory, immune, metabolism and antioxidant responses related genes, as well as the accumulation of PS-MPs in larvae. The results revealed that PS-MPs were observed in the gastrointestinal tract, with a concentration- and exposure time-dependent manner. No significant difference in the larval mortality was found between the treatment groups and the control, whereas the body length of larvae demonstrated a significant reduction at 106 particles/L on 14 days post-hatching. The swimming behaviour of the larvae became hyperactive under exposure to 104 and 106 particles/L PS-MPs. In addition, PS-MP exposure significantly up-regulated the mucin gene transcriptional levels of muc7-like and muc13-like, however down-regulated the mucin gene expression levels of heg1, muc2, muc5AC-like and muc13. The immune- and inflammation and metabolism-relevant genes (jak, stat-3, il-6, il-1ß, tnf-а, ccl-11, nf-κb, and sod) were significantly induced by PS-MPs at 104 and 106 particles/L compared to the control. Taken together, this study suggests that PS-MPs induced inflammation response and might obstruct the immune functions and retarded the growth of the marine medaka larvae even at environmentally relevant concentrations.

Metal Phenolic Network-Integrated Multistage Nanosystem for Enhanced Drug Delivery to Solid Tumors.

Metal-phenolic networks (MPNs) are an emerging class of supramolecular surface modifiers with potential use in various fields including drug delivery. Here, the development of a unique MPN-integrated core-satellite nanosystem (CS-NS) is reported. The "core" component of CS-NS comprises a liposome loaded with EDTA (a metal ion chelator) in the aqueous core and DiR (a near-infrared photothermal transducer) in the bilayer. The "satellite" component comprises mesoporous silica nanoparticles (MSNs) encapsulating doxorubicin and is coated with a Cu2+ -tannic acid MPN. Liposomes and MSNs self-assemble into the CS-NS through adhesion mediated by the MPN. When irradiated with an 808 nm laser, CS-NS liberated the entrapped EDTA, leading to Cu2+ chelation and subsequent disassembly of the core-satellite nanostructure. Photo-conversion from the large assembly to the small constituent particles proceeded within 5 min. Light-triggered CS-NS disassembly enhanced the carrier and cargo penetration and accumulation in tumor spheroids in vitro and in orthotopic murine mammary tumors in vivo. CS-NS is long circulating in the blood and conferred improved survival outcomes to tumor-bearing mice treated with light, compared to controls. These results demonstrate an MPN-integrated multistage nanosystem for improved solid tumor treatment.

Microplastics in three typical benthic species from the Arctic: Occurrence, characteristics, sources, and environmental implications.

Microplastics (MPs) in the Arctic have raised increasing concern, but knowledge on MP contamination in benthic organisms from Arctic shelf regions, e.g., the Chukchi Sea is still limited. Therefore, the present study investigated the occurrence, characteristics, sources, and environmental implications of MPs in the three most common benthic species, namely sea anemone (Actiniidae und.), deposit-feeding starfish (Ctenodiscus crispatus), and snow crab (Chionoecetes opilio), from the Chukchi Sea. The abundances of MPs in the three benthic species were significantly greater than those from the Bering Sea, but lower than those from other regions globally. The top three compositions of MPs in the three species were polyester, nylon, and polyethylene terephthalate. The detection limit for MP size in the present study was 0.03 mm and the mean size of MP in the three species was 0.89 ± 0.06 mm. The surfaces of MPs found in the starfish and crabs were covered with many attachments, cracks, and hollows, while the surfaces of MPs found in the sea anemones were smooth, which was likely a consequence of different feeding behaviors. There was a significantly positive correlation between the abundances of MPs and other anthropogenic substances. The mean MP abundances in the sea anemones ranged from 0.2 items/individual to 1.7 items/individual, which was significantly higher than that in the deposit-feeding starfish (0.1-1.4 items/individual) and snow crabs (0.0-0.6 items/individual). Sea anemones inhabiting lower latitudes ingested relatively higher levels of MPs than those inhabiting higher latitudes. The MP abundances in the sea anemones are significantly and positively correlated with the seasonal reduced ratio of sea ice coverage from August to September. Our findings indicate that sea anemones could function as a bioindicator of MP pollution, and that the MPs in the benthos from the Chukchi Sea might originate from the melting sea ice, fishery activities and ocean currents.

Extra-articular migration of PEEK interference screw after anterior cruciate ligament reconstruction: a report of two cases.

BACKGROUND: The interference screw is the most popular device that fixes the graft for anterior cruciate ligament reconstruction, reducing the incidence of windshield effect and bungee effect. For the screw, either metallic, "bioresorbable," or polyetheretherketone (PEEK) material is available. PEEK is popular and extensively used due to its stability, biocompatibility, radiolucency, and elastic modulus. Rare relevant complications were reported, but here, we report two cases of extra-articular migrations of PEEK interference screw from the tibial tunnel after anterior cruciate reconstruction. CASE REPORT: An 18-year-old boy and a 56-year-old woman underwent anterior cruciate ligament reconstruction using a PEEK interference screw to fix the graft in the tibial tunnel. They suffered from screw extrusion from the tibial tunnel after 40 days and six months, respectively, with an incision rupture or palpable subcutaneous mass. They underwent a second operation and recovered well. CONCLUSIONS: The exact incidence of extra-articular migrations of PEEK interference screws is unknown, but it seems to be quite low; despite this and its uncertain cause, the negative effects caused by the PEEK material need to be considered.

Nanobowl-Supported Liposomes Improve Drug Loading and Delivery.

Liposomal drug delivery for cancer therapy can be limited due to drug leakage in circulation. Here, we develop a new method to enhance the stability of actively loaded liposomal doxorubicin (DOX) through embedding a stiff nanobowl in the liposomal water cavity. Nanobowl-supported liposomal DOX (DOX@NbLipo) resists the influence of plasma protein and blood flow shear force to prevent drug leakage. This approach yields improved drug delivery to tumor sites and enhanced antitumor efficacy. Compared to alternative methods of modifying liposome surface and composition for stability, this approach designs a physical support for an all-aqueous nanoliposomal cavity. Nanobowl stabilization of liposomes is a simple and effective method to improve carrier stability and drug delivery.

Synthesis and Self-Assembly of Cellulose Microfibrils from Reconstituted Cellulose Synthase.

Cellulose, the major component of plant cell walls, can be converted to bioethanol and is thus highly studied. In plants, cellulose is produced by cellulose synthase, a processive family-2 glycosyltransferase. In plant cell walls, individual ß-1,4-glucan chains polymerized by CesA are assembled into microfibrils that are frequently bundled into macrofibrils. An in vitro system in which cellulose is synthesized and assembled into fibrils would facilitate detailed study of this process. Here, we report the heterologous expression and partial purification of His-tagged CesA5 from Physcomitrella patens Immunoblot analysis and mass spectrometry confirmed enrichment of PpCesA5. The recombinant protein was functional when reconstituted into liposomes made from yeast total lipid extract. The functional studies included incorporation of radiolabeled Glc, linkage analysis, and imaging of cellulose microfibril formation using transmission electron microscopy. Several microfibrils were observed either inside or on the outer surface of proteoliposomes, and strikingly, several thinner fibrils formed ordered bundles that either covered the surfaces of proteoliposomes or were spawned from liposome surfaces. We also report this arrangement of fibrils made by proteoliposomes bearing CesA8 from hybrid aspen. These observations describe minimal systems of membrane-reconstituted CesAs that polymerize ß-1,4-glucan chains that coalesce to form microfibrils and higher-ordered macrofibrils. How these micro- and macrofibrils relate to those found in primary and secondary plant cell walls is uncertain, but their presence enables further study of the mechanisms that govern the formation and assembly of fibrillar cellulosic structures and cell wall composites during or after the polymerization process controlled by CesA proteins.

Constructing Implantable SrTiO3 :Yb,Ho Nanofibers for NIR-Triggered and Optically Monitored Chemotherapy.

Light-responsive and photoluminescent (PL) drug-delivery platforms have sparked fascinating advancements in personalized tumor chemotherapy due to their unique characteristics in biological imaging and manipulated release kinetics. Herein, implantable Yb3+ and Ho3+ co-doped strontium titanate (SrTiO3 :Yb,Ho) nanofibers were synthesized and decorated on the surface with polyacrylic acid (PAA) molecules. The preliminary in vitro assay confirmed that this implantable fibrous mesh presented sound cytocompatibility. The PAA surface decoration improved the loading capacity of an anticancer drug (doxorubicin (DOX)) and effectively prevented a daunting burst release in a neutral aqueous environment. Owing to the electrostatic bond between PAA and DOX molecules, low-pH microenvironments and NIR (λ=808 nm) irradiation both induced significantly accelerated DOX release and consequently enhanced the local cancer-cell-killing effect. Additionally, the ratio of green-to-red emission (I545 /I655 ) from the SrTiO3 :Yb,Ho-PAA fibers responded effectively to the DOX release progress and dosage due to a fluorescence resonance energy transfer (FRET) effect. This unique characteristic enabled optical monitoring of the delivery progress in a timely manner. These SrTiO3 :Yb,Ho-PAA nanofibers, with precise dual-triggering and optical monitoring of DOX release, are expected to serve as a new implantable drug delivery platform for personalized chemotherapy in the future.

Ultrasound-propelled liposome circumvention and siRNA silencing reverse BRAF mutation-arised cancer resistance to trametinib.

BRAF-V600E mutation is regarded as the source of lung cancer resistance to trametinib (Tr), and no solution available for completely addressing this intractable resistance has emerged yet. Herein, the combination of ultrasonic (US) propelled folic acid (FA)-modified liposomes strategy and BRAF-driven gene silencing program is proposed to effectively reverse Tr's resistance to lung cancer. Meanwhile, the prepared cationic nanoliposomes can assist Tr drug and BRAF siRNA to escape lysosome disposal, thereby avoiding Tr drug pumping out or siRNA degradation. More significantly, loaded BRAF siRNA is designed to silence BRAF-V600E mutation genes via modulating BRAF-ERK-pathway and remarkably reverse the PC9R resistance to Tr. Systematic experiments validate that these cooperatively sensitize PC9R cells to Tr and shrink resistant NSCLC in vivo, especially after combining with FA-mediated targeting and US-enhanced permeability that permits more intratumoral accumulations of Tr. Such a biocompatible targeting drug-resistance liberation agent and its underlying design strategy lay a foundation avenue to completely reverse tumor resistance, which is preferable to treat BRAF mutation-arised resistance of various tumors, holding high clinical translation potentials.

First evidence of meso- and microplastics on the mangrove leaves ingested by herbivorous snails and induced transcriptional responses.

Although evidence suggests the ubiquity of meso- and microplastics (MMPs) in mangrove forests, our knowledge of their bioavailability and risk on mangrove leaves is scarce. Here, we investigated MMP contamination concerning submerged mangrove leaves and herbivorous snails that mainly feed on them from the four mangrove forests located in Beibu Gulf, Guangxi Province, China. Results showed that the MMP abundance on the mangrove leaves ranged from 0.01 ± 0.00 to 0.42 ± 0.15 items cm-2, while it ranged from 0.33 ± 0.21 to 6.20 ± 2.91 items individual-1 in the snails. There were significant positive correlations between snails and leaves regarding the abundance of total MMPs and the proportions of MMPs with the same characteristics. Expanded polystyrene (EPS) that mainly derived from aquaculture rafts, accounted for a major component both on the leaves and in the snails in Shi Jiao (SJ). Both the detection frequency and percentage of larger EPS (2.00-17.50 mm) on the leaves in SJ were higher than other sites. Meanwhile, the detection frequency, abundance and percentage of larger EPS on the leaves had significant positive correlations with those of micro-EPS in the snails. These findings suggested that mangrove leaves may represent a viable pathway for MMPs to enter the herbivorous snails. Larger EPS with higher frequency of occurrence on mangrove leaves were more likely to be encountered and ingested by snail considering its opportunistic feeding behavior. In addition, 11 sensitive genes involved in the processes of metabolism, intestinal mucosal immune systems, and cellular transduction in the snails were significantly suppressed by MMP exposure, which may be potentially used as early biomarkers to indicate the biological effects of MMPs under realistic environmental conditions. Overall, this study provides novel insights into the fate, sources, and biological effects of MMPs on mangrove leaves.

Systematical insights into distribution and characteristics of microplastics in near-surface waters from the East Asian Seas to the Arctic Central Basin.

The spatial distribution and composition of microplastics in near-surface water (8 m) was investigated from the East Asian Seas to the Arctic Central Basin. Microplastics were detected in 93.9% of the sampling sites. Abundances ranged from 0.48 to 7.62 items/m3, with an average abundance of 2.91 ± 1.93 items/m3. The highest average abundance was observed in the Arctic Central Basin. Polyester (PET) was the dominant type, accounting for 71.3% of total microplastics, followed by rayon or cellophane and polytetrafluoroethylene (PTFE). Microplastics < 2 mm accounted for 81.9% of total particles. Its distribution peaked in the 1-2 mm size range. The 0.30-2 mm fibers were the most abundant. In the East Asian Seas, the abundance was significantly negatively correlated with longitude, whereas the accumulation of microplastics was not observed in the northeastern sector of Japan Sea. Abundances of microplastics at sites located in the sub-Arctic and Arctic Oceans showed a significant positive relationship with latitude, indicating that the Arctic Ocean is a potential accumulation zone of microplastics. The findings of this study will provide systematical insights into distribution of microplastics and basic information for understanding the accumulation mechanism of microplastics in near-surface waters from the East Asian Seas to the Arctic Central Basin.

Spatio-temporal variation of microplastic pollution in the sediment from the Chukchi Sea over five years.

Sediment has been considered as an important sink for microplastics (MPs), but there are limited reports about the spatial and temporal variability of MPs in sediment from the Arctic Ocean. Furthermore, understanding is lacking on the correlation between Arctic sea ice variation and MP abundance in sediment. This study aimed to assess the MP contamination in the sediment from the Chukchi Sea over five years through three voyages (in 2016, 2018, and 2020). The MP abundances in the sediments from the Chukchi Plateau and Chukchi Shelf over five years ranged from 33.66 ± 15.08 to 104.54 ± 28.07 items kg-1 dry weight (DW) and 20.63 ± 6.71 to 55.64 ± 22.61 items kg-1 DW, respectively. The MP levels from the Chukchi Sea were lower than those from the Eastern Arctic Ocean. Our findings suggest that the Chukchi Plateau is an accumulation zone for fibers related to fishing gear and textiles under the dual influence of the Pacific and Atlantic Ocean currents. However, the reduction of these fibers in the sediment from the Chukchi Shelf might be related to bottom currents, sediment resuspension, and biomass. Moreover, the MP abundance in the sediment from the Chukchi Sea was positively correlated with the reduction of Arctic sea ice, suggesting that the melting sea ice contributes to the increase in MP levels in the sediment. The increase in blue MPs from the Chukchi Plateau over time might be attributed to melting sea ice or intense fishing activity, whereas the increase of the smallest MPs in this region could be owing to the breakdown of larger plastics during long-distance transport or the easier settlement of smaller MPs. Further time-series investigations are urgently required to improve the understanding of the environmental fate and transport of MPs among the different Arctic environmental compartments.

The prevalence and potential implications of microplastic contamination in marine fishes from Xiamen Bay, China.

The wide presence of microplastics (MPs) in the ocean leads their exposure on marine fish. MP contamination was reported for the gastrointestinal tracts and gills of 117 marine fishes attributed to nine species from Xiamen Bay, a special economic zone in China. Among species, MP abundance ranged from 1.07 items individual-1 to 8.00 items individual -1. Fibers dominated MP shapes, accounting for 59.03% of all MPs. Polymer composition was dominated by polyamide (26.97%) and rayon (17.56%). MPs were most commonly (55.22%) transparent, and most (77.61%) were < 1 mm in size. Our report represents the first of MP contamination in wild marine fish from Xiamen Bay, which we determine to be at an intermediate to slightly higher level compared with levels reported elsewhere, and provides further insights into potential risks of MPs pose to fish and human health.

Biomimetic Liposomal Nanoplatinum for Targeted Cancer Chemophototherapy.

Photodynamic therapy (PDT) of cancer is limited by tumor hypoxia. Platinum nanoparticles (nano-Pt) as a catalase-like nanoenzyme can enhance PDT through catalytic oxygen supply. However, the cytotoxic activity of nano-Pt is not comprehensively considered in the existing methods to exert their multifunctional antitumor effects. Here, nano-Pt are loaded into liposomes via reverse phase evaporation. The clinical photosensitizer verteporfin (VP) is loaded in the lipid bilayer to confer PDT activity. Murine macrophage cell membranes are hybridized into the liposomal membrane to confer biomimetic and targeting features. The resulting liposomal system, termed "nano-Pt/VP@MLipo," is investigated for chemophototherapy in vitro and in vivo in mouse tumor models. At the tumor site, oxygen produced by nano-Pt catalyzation improves the VP-mediated PDT, which in turn triggers the release of nano-Pt via membrane permeabilization. The ultrasmall 3-5 nm nano-Pt enables better penetration in tumors, which is also facilitated by the generated oxygen gas, for enhanced chemotherapy. Chemophototherapy with a single injection of nano-Pt/VP@MLipo and light irradiation inhibits the growth of aggressive 4T1 tumors and their lung metastasis, and prolongs animal survival without overt toxicity.

Microplastic pollution in wild commercial nekton from the South China Sea and Indian Ocean, and its implication to human health.

Marine biota, especially commercially important species, serves as a basis for human nutrition. However, millions of tons of plastic litter are produced and enter the marine environment every year, with potential adverse impacts on marine organisms. In the present study, we investigated the occurrence and characteristics of microplastic (MP) pollution in the digestive tracts of 13 species of wild nektons from 20 stations sampled in the South China Sea (SCS) and the Indian Ocean (IO), and assessed the human health risks of MPs. The detection rate of MPs ranged from 0.00% to 50.00% from the SCS, which was dramatically lower than that from the IO (10.00-80.00%). The average abundance of MP was 0.18 ± 0.06 items g wet weight-1 (ww-1) in the SCS, which was significantly lower than that in the IO with a concentration of 0.70 ± 0.16 items g ww-1. Most MPs were fibers in type, black in color, and polyester (PES) in polymer composition in both the SCS and IO. Interestingly, distinct profiles of MP pollution were found between the benthic and pelagic nektons: 1) The predominant MP composition was PES in the benthic nektons, whereas polyamide (PA) accounted for a larger part of the total MP count in the pelagic nektons within the SCS; 2) The abundance of MP in the benthic nektons (0.52 ± 0.24 items individual-1) was higher than that in the pelagic nektons (0.30 ± 0.11 items individual-1). Accordingly, the mean hazard score of MPs detected in the benthic nektons (220.66 ± 210.75) was higher than that in the pelagic nektons (49.53 ± 22.87); 3) The mean size of the MP in the pelagic nektons (0.84 ± 0.17 mm) was larger than that in the benthic nektons (0.49 ± 0.09 mm). Our findings highlight the need to further investigate the ecological impacts of MPs on wild nekton, especially commercially important species, and its potential implications for human health.

Microplastics decrease the toxicity of triphenyl phosphate (TPhP) in the marine medaka (Oryzias melastigma) larvae.

Plastics have been recognized as a serious threat to the environment. Besides their own toxicity, microplastics can interact with other environmental pollutants, acting as carriers and potentially modulating their toxicity. In this study, the toxicity of polystyrene (PS) microplastic fragments (plain PS; carboxylated PS, PS-COOH and aminated PS, PS-NH2) and triphenyl phosphate (TPhP) (an emerging organophosphate flame retardant) at the environmentally relevant concentrations to the marine medaka (Oryzias melastigma) larvae was investigated. Larvae were exposed to 20 µg/L of microplastic fragments or 20 and 100 µg/L of TPhP or a combination of both for 7 days. The results showed that the three microplastics did not affect the larval locomotor activity. For TPhP, the larval moving duration and distance moved were significantly decreased by the TPhP exposure, with a maximum decrease of 43.5% and 59.4% respectively. Exposure to 100 µg/L TPhP respectively down-regulated the expression levels of sine oculis homeobox homologue 3 (six3) and short wavelength-sensitive type 2 (sws2) by 19.1% and 41.7%, suggesting that TPhP might disturb eye development and photoreception and consequently the low locomotor activity in the larvae. Interestingly, during the binary mixture exposure, the presence of PS, PS-COOH or PS-NH2 reversed the low locomotor activity induced by 100 µg/L TPhP to the normal level. Relative to the larvae from the 100 µg/L TPhP group, the movement duration and distance moved were increased by approximately 60% and 100%, respectively, in the larvae from the TPhP + PS, TPhP + PS-COOH and TPhP + PS-NH2 groups. However, the gene expression profiles were distinct among the fish from the TPhP + PS, TPhP + PS-COOH and TPhP + PS-NH2 groups, implying different mechanisms underlying the reversal of the locomotor activity. The findings in this study challenge the general view that microplastics aggravate the toxicity of the adsorbed pollutants, and help better understand the environmental risk of microplastic pollution.

Effects of feed solution characteristics and membrane fouling on the removal of THMs by UF/NF/RO membranes.

Ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) are widely used in drinking water treatment and wastewater recycling. However, limited information was available regarding their performance in removing trihalomethanes (THMs). The present study investigated the effect of feed solution characteristics and membrane fouling on THM removal by UF/NF/RO membranes. The results indicated that THMs were poorly removed by UF membrane, and the removal was dominated by hydrophobic adsorption. In contrast, high removal of THMs was observed for NF/RO membranes, which was contributed by both size exclusion and hydrophobic adsorption. By comparing the adsorption of THMs on NF/RO membranes at different feed concentration, it was found that the role of hydrophobic adsorption was more important at lower feed concentration. The removal of THMs by UF/NF/RO membranes increased with increasing feed concentration, which can be ascribed to the enhanced diffusion at higher concentration gradient. With increasing ionic strength, THM removal was decreased significantly for UF membrane, but the removal by NF/RO membranes remained largely unchanged. By comparing THM removal by clean and fouled membranes, the effect of membrane fouling was examined. The removal of most THMs (except trichloromethane) decreased after fouling for UF membrane, whereas decreased removal was only observed for iodinated THMs for fouled NF/RO membranes.

Has the formation of disinfection by-products been overestimated? Membrane leakage from syringe filter heads serves as unexpected precursors.

Syringe filters are widely used for sample pretreatments in laboratories. This study found that, surprisingly, these filters can leak dissolved organic carbon (DOC) that can potentially serve as precursors of disinfection by-products (DBPs). Nine common types of syringe filters were assessed. The results showed that the DOC of ultrapure water increased after syringe filtration. The DOC shed from filter membranes was characterized, whose spectra showed that the main compounds exhibited a low apparent molecular weight. Five classes of DBPs were investigated including trihalomethanes, haloacetaldehydes, haloacetonitriles, haloacetamides and halonitromethanes, among which trichloromethane (TCM), dichloroacetaldehyde (DCAL), trichloroacetaldehyde (TCAL), dichloroacetonitrile (DCAN), and trichloronitromethane (TCNM) were principally detected. The DBP formation was affected by chlorination time and membrane types. In general, the use of the poly vinylidene fluoride membrane resulted in the highest formation of TCM and TCAL, whereas nylon and mixed cellulose esters membranes contributed significantly to the formation of DCAN and TCNM, respectively. The shedding DOC and the formation of TCM, DCAL and TCAL from filter membranes were mitigated effectively by pre-washing; however, the contribution of membrane leakage to DCAN and TCNM formation was still notable, even with a pre-wash volume of 50 mL. When unwashed syringe filters were used for a real water sample, the DBP formation increased by up to 73.2% compared to the pre-washed ones; particularly for TCNM it was always over 15%. Therefore, for better quality control in laboratories, more attention should be paid to the syringe filters during sample pre-treatments, particularly when DBP formation is being investigated.

Coupled effects of urbanization level and dam on microplastics in surface waters in a coastal watershed of Southeast China.

Investigating the heterogeneous distribution pattern of plastic pollution in river systems is useful for better understanding the transport pathways of plastics from land to sea. Therefore, we analyzed samples from 17 sites to evaluate the distribution pattern of microplastics (MPs) in Minjiang River Watershed. The MP concentrations ranged between 0.12 and 2.72 n/L, with higher microplastic concentrations located in urban areas with greater population and gross domestic product (GDP) densities. MP concentrations were positively correlated with population density, GDP density, and built-up land use percentage, suggesting that increasing urbanization level will lead to greater plastic pollution. MP concentrations spanning the upstream and downstream sides of the SK Hydropower Dam showed decreasing trends, suggesting that MP settling would occur behind the dam and Shuikou Reservoir might serve as a sink for MPs. This study provides useful insight for revealing the effects of urbanization and dams on spatial distribution of riverine MPs.

Microplastics negatively impact embryogenesis and modulate the immune response of the marine medaka Oryzias melastigma.

Microplastic (MP) pollution is an emerging contaminant in aquatic environments worldwide. Nonetheless, the developmental toxicity of MPs in the early life stages of fish and the mechanisms involved are not yet fully understood. The present study investigated the effects of different concentrations of polystyrene (PS) MPs on the early development of the marine model fish the medaka Oryzias melastigma. Our results showed that waterborne exposure to PS MPs significantly delayed the hatching time, altered the heartbeat and decreased the hatching rate of embryos. Furthermore, the genes involved in cardiac development, encoding for embryo-hatching enzymes, as well as inflammatory responses were significantly upregulated. The transcriptome results showed that mainly the pathways involved in metabolism, immune response, genetic information processing and diseases were significantly enriched. These results demonstrate that PS MPs negatively impact embryogenesis and the immune response of O. melastigma.

Microplastics abundance and characteristics in surface waters from the Northwest Pacific, the Bering Sea, and the Chukchi Sea.

Microplastics (MPs) in the Arctic Ocean have gained considerable attention due to its ubiquity and impacts within ecosystems. However, little information is available on MPs in the Pacific section of the Arctic Ocean. The present study determined the abundance, distribution, and composition of MPs in surface waters from the Northwestern Pacific, the Bering Sea, and the Chukchi Sea. The MPs abundances varied from 0.018 items/m3 to 0.31 items/m3, with a mean abundance of 0.13 ±â€¯0.11 items/m3. The highest level of MPs was found in the Chukchi Sea. Of all of the detected MPs, polyethylene terephthalate (PET) accounted for the largest proportion of MPs, and fiber was predominant with regard to the total amount. Our results highlighted that the Arctic Ocean is becoming a hotspot for plastic pollution, and the risks posed by MPs need to be paid closer attention in future investigations.