Bioaccumulation of polystyrene nanoplastics and BDE-209 induced oxidative stress, photosynthesis and growth impairments in floating fern Salvinia natans

Endocytosis, endoplasmic reticulum, actin cytoskeleton affected in tilapia liver under polystyrene microplastics and BDE153 acute co-exposure

Studies showed that contaminants adhered to the surface of nano-polystyrene microplastics (NPs) have a toxicological effect. Juveniles tilapia were dispersed into four groups: the control group A, 75 nm NPs exposed group B, 5 ng·L-1 2,2',4,4',5,5'-hexabromodiphenyl ether group C (BDE153), and 5 ng·L-1 BDE153 + 75 nm MPs group D, and acutely exposed for 2, 4 and 8 days. The hepatic histopathological change, enzymatic activities, transcriptomics, and proteomics, have been performed in tilapia. The results showed that the enzymatic activities of anti-oxidative (ROS, SOD, EROD), energy (ATP), lipid metabolism (TC, TG, FAS, LPL, ACC), pro-inflammatory (TNFα, IL-1β) and apoptosis (caspase 3) significantly increased at 2 d in BDE153 and the combined group and together in BDE153 group at 8 d. Histological slice showed displaced nucleus by BDE153 exposure and vacuoles appeared in the combined groups. KEGG results revealed that pathways associated with endocytosis, protein processing in endoplasmic reticulum and regulation of actin cytoskeleton were significantly enriched. The selected genes associated with neurocentral development (ganab, diaph3/baiap2a/ddost decreased and increased), lipid metabolism (ldlrap1a decreased, stt3b increased), energy (agap2 decreased, uggt1 increased) were affected under co-exposure, and fibronectin significantly increased via proteome. Our study indicated that endocytosis, protein processing in endoplasmic reticulum, regulation of actin cytoskeleton were affected in tilapia liver under NPs and BDE153 co-exposure.

Polyethylene nanoplastics affected morphological, physiological, and molecular indices in tomato (Solanum lycopersicum L.)

This study explored morphological, physiological, molecular, and epigenetic responses of tomatoes (Solanum lycopersicum) to soil contamination with polyethylene nanoplastics (PENP; 0.01, 0.1, and 1 gkg-1 soil). The PENP pollution led to severe changes in plant morphogenesis. The PENP treatments were associated with decreased plant biomass, reduced internode length, delayed flowering, and prolonged fruit ripening. Abnormal inflorescences, flowers, and fruits observed in the PENP-exposed seedlings support genetic changes and meristem dysfunction. Exposure of seedlings to PENP increased H2O2 accumulation and damaged membranes, implying oxidative stress. The PENP treatments induced activities of catalase (EC1.11.1.6), peroxidase (EC1.11.1.7), and phenylalanine ammonia-lyase (EC4.3.1.24) enzymes. Soil contamination with PENP also decreased the net photosynthesis, maximum photosystem efficiency, stomatal conductance, and transpiration rate. The nano-pollutant upregulated the expression of the histone deacetylase (HDA3) gene and R2R3MYB transcription factor. However, the AP2a gene was down-regulated in response to the PENP treatment. Besides, EPNP epigenetically contributed to changes in DNA methylation. The concentrations of proline, soluble phenols, and flavonoids also displayed an upward trend in response to the applied PENP treatments. The long-term exposure of seedlings to PENP influenced fruit biomass, firmness, ascorbate, lycopene, and flavonoid content. These findings raise concerns about the hazardous aspects of PENP to agricultural ecosystems and food security.

Enhanced competitiveness of Spirodela polyrhiza in co-culture with Salvinia natans under combined exposure to polystyrene nanoplastics and polychlorinated biphenyls

Micro- and nanoplastics (MNPs) and polychlorinated biphenyls (PCBs) are prevalent in the environment and pose potential threats to ecosystems. However, studies on the phytotoxicity of MNPs and PCBs on primary producers are limited. This study investigated the effects of polystyrene nanoplastics (PS-NPs, 10 mg/L) and 2,2',5,5'-tetrachlorobiphenyl (PCB-52, 0.1 mg/L), on the growth of Spirodela polyrhiza and Salvinia natans, and their impact on plant competitive ability under co-culture conditions. Laser confocal microscopy images revealed that PS-NPs accumulated on the leaf and root surfaces of both species. Combined exposure to PS-NPs and PCB-52 significantly inhibited the average specific and relative growth rates (RGR) of both species, reduced chlorophyll a and b levels, and slightly increased carotenoid content, disrupting the photosynthetic system. PCB-52 exacerbated PS-NPs accumulation on plants, leading to increased hydrogen peroxide (H2O2) and superoxide anion (O2-) production in both roots and leaves. This affects the activity of superoxide dismutase (SOD), peroxidase (POD), malondialdehyde (MDA), and the soluble protein content. The combined treatment with PS-NPs and PCB-52 induced greater ecological stress in both species than the treatment with PS-NPs alone. In addition, the combined treatment with PS-NPs and PCB-52 significantly improved the relative yield and competition balance index of S. polyrhiza, indicating that PS-NPs + PCB-52 enhanced the competitive ability of S. polyrhiza when co-cultured with S. natans. This study confirmed the effects of co-exposure to PS-NPs and PCB-52 on aquatic plant growth and species competition, contributing to better insight into the ecological impacts of MNPs and organic pollutants.

Toxic effects of polystyrene nanoplastics and polycyclic aromatic hydrocarbons (chrysene and fluoranthene) on the growth and physiological characteristics of Chlamydomonas reinhardtii

While the toxicity of nano-microplastics and polycyclic aromatic hydrocarbons (PAHs) to aquatic organisms is well-studied, their joint impact on microalgae is less explored. This study focused on single and combined effects of PS-NPs (30 nm; concentrations: 2, 5, 10, and 25 mg/L) and two PAHs (chrysene and fluoranthene at 10, 100 µg/L) for 96 h on the accumulation, growth, photosynthetic parameters, and oxidative stress in the Chlamydomonas reinhardtii. The findings revealed that exposure to increasing concentrations of PS-NPs significantly reduced the growth inhibition ratio and chlorophyll-a content after 96 h. Both PAHs (100 µg/L) + PS-NPs (25 mg/L), significantly reduced the growth inhibition ratio and chlorophyll-a levels. Individual and combined exposures of PS-NPs and PAHs can prompt antioxidant responses like SOD, GPx, and GST, as well as an unaffected level of non-enzymatic antioxidant GSH and diminished CAT activity. Furthermore, both PAHs + PS-NPs triggered ROS levels, resulting in cell membrane damage. However, the reduced oxidative effect of LPO of combined exposures can be attributed to the activation of antioxidant defenses. In addition, the microscopic visualization data shows that PS-NPs adhered to the surface of microalgae. Also, PS-NPs reduced the adsorption of PAHs on the surface of C. reinhardtii. Altogether, this study implied that the influence of coexistent PS-NPs should be considered in the environmental risk assessment of PAHs in aquatic environments.