Polystyrene nanoplastic and engine oil synergistically intensify toxicity in Nile tilapia, Oreochromis niloticus : Polystyrene nanoplastic and engine oil toxicity in Nile tilapia.

Polystyrene nanoplastic (PS-NPs) and Engine oil (EO) pose multiple ecotoxic effects with increasing threat to fish ecosystems. The current study investigated the toxicity of 15 days exposure to PS-NPs and / or EO to explore their combined synergistic effects on Nile tilapia, Oreochromis niloticus (O. niloticus). Hematobiochemical parameters, proinflammatory cytokines, and oxidative stress biomarkers as well as histological alterations were evaluated. The experimental design contained 120 acclimated Nile tilapia distributed into four groups, control, PS-NPs (5 mg/L), EO (1%) and their combination (PS-NPs + EO). After 15-days of exposure, blood and tissue samples were collected from all fish experimental groups. Results indicated that Nile tilapia exposed to PS-NPs and / or EO revealed a significant decrease in almost all the measured hematological parameters in comparison to the control, whereas WBCs and lymphocyte counts were significantly increased in the combined group only. Results clarified that the combined PS-NPs + EO group showed the maximum decrease in RBCs, Hb, MCH and MCHC, and showed the maximum significant rise in interleukin-1ß (IL-1ß), and interleukin-6 (IL-6) in comparison to all other exposed groups. Meanwhile, total antioxidant capacity (TAC) showed a significant (p < 0.05) decline only in the combination group, whereas reduced glutathione (GSH) showed a significant decline in all exposed groups in comparison to the control. Both malondialdehyde (MDA) and aspartate aminotransferase (AST) showed a significant elevation only in the combination group. Uric acid showed the maximum elevation in the combination group than all other groups, whereas creatinine showed significant elevation in the EO and combination group when compared to the control. Furthermore, the present experiment proved that exposure to these toxicants either individually or in combination is accompanied by pronounced histomorpholgical damage characterized by severe necrosis and hemorrhage of the vital organs of Nile tilapia, additionally extensively inflammatory conditions with leucocytes infiltration. We concluded that combination exposure to both PS-NPs and EO caused severe anemia, extreme inflammatory response, oxidative stress, and lipid peroxidation effects, thus they can synergize with each other to intensify toxicity in fish.

Polystyrene nanoparticles induce biofilm formation in Pseudomonas aeruginosa.

In recent years, micro/nanoplastics have garnered widespread attention due to their ecological risks. In this study, we investigated the effects of polystyrene nanoparticles (PS-NPs) of different sizes on the growth and biofilm formation of Pseudomonas aeruginosa PAO1. The results demonstrated that exposure to certain concentrations of PS-NPs significantly promoted bacterial biofilm formation. Meanwhile, we comprehensively revealed its mechanism whereby PS-NPs induced oxidative stress and altered bacterial membrane permeability by contacting or penetrating bacterial membranes. To counteract the stimulation by PS-NPs and reduce their toxicity, bacteria enhanced biofilm formation by upregulating the expression of biofilm-related genes, increasing EPS and virulence factors secretion, and enhancing bacterial motility through the participation of the quorum sensing (QS) system. Additionally, we also found that exposure to PS-NPs enhanced bacterial antibiotic resistance, posing a challenge to antimicrobial therapy. Our study reveals the toxic effects of nanoplastics and the defense mechanisms of bacteria, which has important implications for the risk assessment and management of environmental nanoplastics.

Mechanistic insight into the impact of polystyrene microparticle on submerged plant during asexual propagules germination to seedling: Internalization in functional organs and alterations of physiological phenotypes.

Asexual reproduction is one of the most important propagations in aquatic plants. However, there is a lack of information about the growth-limiting mechanisms induced by microplastics on the submerged plant during asexual propagule germination to seedling. Hence, we investigated the effects of two sizes (2 µm, 0.2 µm) and three concentrations (0.5 mg/L, 5 mg/L, and 50 mg/L) of polystyrene microplastics (PSMPs) on Potamogeton crispus turion germination and seedling growth. Both PSMPs sizes were found in P. crispus seedling tissues. Metabolic profile alterations were observed in leaves, particularly affecting secondary metabolic pathways and ATP-binding cassette transporters. Metal elements are indispensable cofactors for photosynthesis; however, alterations in the metabolic profile led to varying degrees of reduced concentrations in magnesium, iron, copper, and zinc within P. crispus. Therefore, the maximum quantum yield of photosystem II significantly decreased in all concentrations with 0.2 µm-PSMPs, and at 50 mg/L with 2 µm-PSMPs. These findings reveal that internalization of microplastics, nutrient absorption inhibition, and metabolic changes contribute to the negative impact on P. crispus seedlings.

Elucidating polyethylene microplastic degradation mechanisms and metabolic pathways via iron-enhanced microbiota dynamics in marine sediments.

The extensive use of plastics has given rise to microplastics, a novel environmental contaminant that has sparked considerable ecological and environmental concerns. Biodegradation offers a more environmentally friendly approach to eliminating microplastics, but their degradation by marine microbial communities has received little attention. In this study, we used iron-enhanced marine sediment to augment the natural bacterial community and facilitate the decomposition of polyethylene (PE) microplastics. The introduction of iron-enhanced sediment engendered an augmented bacterial biofilm formation on the surface of polyethylene (PE), thereby leading to a more pronounced degradation effect. This novel observation has been ascribed to the oxidative stress-induced generation of a variety of oxygenated functional groups, including hydroxyl (-OH), carbonyl (-CO), and ether (-C-O) moieties, within the microplastic substrate. The analysis of succession in the community structure of sediment bacteria during the degradation phase disclosed that Acinetobacter and Pseudomonas emerged as the principal bacterial players in PE degradation. These taxa were directly implicated in oxidative metabolic pathways facilitated by diverse oxidase enzymes under iron-facilitated conditions. The present study highlights bacterial community succession as a new pivotal factor influencing the complex biodegradation dynamics of polyethylene (PE) microplastics. This investigation also reveals, for the first time, a unique degradation pathway for PE microplastics orchestrated by the multifaceted marine sediment microbiota. These novel insights shed light on the unique functional capabilities and internal biochemical mechanisms employed by the marine sediment microbiota in effectively degrading polyethylene microplastics.

Potential Effects of Orally Ingesting Polyethylene Terephthalate Microplastics on the Mouse Heart.

Polyethylene terephthalate microplastics (PET MPs) are widespread in natural environment, and can enter organisms and accumulate in the body, but its toxicity has not been well studied. Therefore, in order to investigate the toxic effects of PET microplastics on mammals, this study investigated the toxic effects of PET MPs on ICR mice and H9C2 cells by different treatment groups. The results indicated the cardiac tissue of mice in the PET-H (50 µg/mL) group showed significant capillary congestion, myocardial fiber breakage, and even significant fibrosis compared to the PET-C (control) group (P < 0.01). Results of the TUNEL assay demonstrated significant apoptosis in myocardial tissue in the PET-H and PET-M (5 µg/mL) groups (P < 0.01). Meanwhile, Western blotting showed increased expression of the apoptosis-related protein Bax and decreased expression of PARP, caspase-3, and Bcl-2 proteins in both myocardial tissues and H9C2 cells. In addition, flow cytometry confirmed that PET MPs decreased the mitochondrial membrane potential and apoptosis in H9C2 cells; however, this trend was reversed by N-acetylcysteamine application. Moreover, PET MP treatment induced the accumulation of reactive oxygen species (ROS) in H9C2 cells, while the MDA level in the myocardial tissue was elevated, and the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) were decreased (P < 0.01), indicating a change in the redox environment. In conclusion, PET MPs promoted cardiomyocyte apoptosis by inducing oxidative stress and activating mitochondria-mediated apoptotic processes, ultimately leading to myocardial fibrosis. This study provides ideas for the prevention of PET MP toxicity and promotes thinking about enhancing plastic pollution control.

Chronic exposure to polytetrafluoroethylene microplastics caused sex-specific effects in the model insect, Drosophila melanogaster (Diptera: Drosophilidae).

Microplastics (MPs) have become a prominent environmental concern due to their ubiquity in various ecosystems and widespread distribution through multiple channels. In this study, the oral effects of 2,000 mesh polytetrafluoroethylene (PTFE) microplastics were tested against Drosophila melanogaster (Meigen), at concentrations of 0, 0.1, 1, 10, and 20. After exposure to a microplastic-containing medium for 20 days, energy metabolism, fecundity, spontaneous movement, and sleeping time were measured. The study results showed that glucose levels in male flies were significantly reduced after exposure to PTFE-MPs. Measurement of lipid and protein levels indicated an increase in males but decrease in females, whereas these changes were not statistically significant. Reduction in sleep time was also observed, especially in males at the concentration of 20 g/l. Our study indicates that chronic exposure of PTFE-MPs can change energy metabolism and the amount of sleep on D. melanogaster in a sex dependent and dose dependent way. The results of our study are hoped to contribute to a better understanding of the effects of microplastics as new pollutants on insects.

Obesogenic polystyrene microplastic exposures disrupt the gut-liver-adipose axis.

Microplastics (MP) derived from the weathering of polymers, or synthesized in this size range, have become widespread environmental contaminants and have found their way into water supplies and the food chain. Despite this awareness, little is known about the health consequences of MP ingestion. We have previously shown that the consumption of polystyrene (PS) beads was associated with intestinal dysbiosis and diabetes and obesity in mice. To further evaluate the systemic metabolic effects of PS on the gut-liver-adipose tissue axis, we supplied C57BL/6J mice with normal water or that containing 2 sizes of PS beads (0.5 and 5 µm) at a concentration of 1 µg/ml. After 13 weeks, we evaluated indices of metabolism and liver function. As observed previously, mice drinking the PS-containing water had a potentiated weight gain and adipose expansion. Here we found that this was associated with an increased abundance of adipose F4/80+ macrophages. These exposures did not cause nonalcoholic fatty liver disease but were associated with decreased liver:body weight ratios and an enrichment in hepatic farnesoid X receptor and liver X receptor signaling. PS also increased hepatic cholesterol and altered both hepatic and cecal bile acids. Mice consuming PS beads and treated with the berry anthocyanin, delphinidin, demonstrated an attenuated weight gain compared with those mice receiving a control intervention and also exhibited a downregulation of cyclic adenosine monophosphate (cAMP) and peroxisome proliferator-activated receptor (PPAR) signaling pathways. This study highlights the obesogenic role of PS in perturbing the gut-liver-adipose axis and altering nuclear receptor signaling and intermediary metabolism. Dietary interventions may limit the adverse metabolic effects of PS consumption.

Low-density polyethylene enhances the disturbance of microbiome and antibiotic resistance genes transfer in soil-earthworm system induced by pyraclostrobin.

Non-antibiotic chemicals in farmlands, including microplastics (MPs) and pesticides, have the potential to influence the soil microbiome and the dissemination of antibiotic resistance genes (ARGs). Despite this, there is limited understanding of the combined effects of MPs and pesticides on microbial communities and ARGs transmission in soil ecosystems. In this study, we observed that low-density polyethylene (LDPE) microplastic enhance the accumulation of pyraclostrobin in earthworms, resulting in reduced weight and causing severe oxidative damage. Analysis of 16 S rRNA amplification revealed that exposure to pyraclostrobin and/or LDPE disrupts the microbial community structure at the phylum and genus levels, leading to reduced alpha diversity in both the soil and earthworm gut. Furthermore, co-exposure to LDPE and pyraclostrobin increased the relative abundance of ARGs in the soil and earthworm gut by 2.15 and 1.34 times, respectively, compared to exposure to pyraclostrobin alone. It correlated well with the increasing relative abundance of genera carrying ARGs. Our findings contribute novel insights into the impact of co-exposure to MPs and pesticides on soil and earthworm microbiomes, highlighting their role in promoting the transfer of ARGs. This knowledge is crucial for managing the risk associated with the dissemination of ARGs in soil ecosystems.

Evidence of parental transfer of nanoplastics in pea (Pisum sativum) plants.

The increasing abundance of nanoplastics in the environment is a cause of serious concern and its acute and chronic effects on ecosystems need to be thoroughly investigated. Toward this end, this study investigated the parental transfer of nanoplastics by chronically exposing Pisum sativum (pea) plants to nanoplastics through soil medium. We observed the presence of nanoplastics in harvested fruits and a subsequent generation of plants replanted in uncontaminated soil using confocal laser scanning microscopy. The fluorescence was located in the cell wall of the vascular bundles, but not in the epidermis, indicating the parental transfer of nanoplastics. In addition, we determined the effects of nanoplastics on the health of subsequent plant generations by estimating the reproductive factors and measuring the content of individual nutrients in peas. Decreases in crop yield and fruit biomass, in addition to changes in nutrient content and composition, were noted. The transgenerational effects of nanoplastics on plants can profoundly impact terrestrial ecosystems, including both plant species and their predators, raising critical safety concerns. Our findings highlight the evidence of parental transfer of nanoplastics in the soil through plants and shows that the chronic effects of nanoplastics on plants may pose a threat to the food supply.

Surface-Charge-Driven Ferroptosis and Mitochondrial Dysfunction Is Involved in Toxicity Diversity in the Marine Bivalve Exposed to Nanoplastics.

Nanoplastics (NPs) pervade daily life, posing serious threats to marine ecosystems. Despite the crucial role that surface charge plays in NP effects, there is a substantial gap in our understanding of how surface charge influences NP toxicity. Herein, by exposing Ruditapes philippinarum (R. philippinarum) to both positively charged NPs (p-NPs) and negatively charged NPs (n-NPs) at environmentally relevant particle number levels for a duration of 35 days, we unequivocally demonstrate that both types of NPs had discernible impacts on the clams depending on their surface charge. Through transcriptomic and proteomic analyses, we unveiled the primary mechanisms behind p-NP toxicity, which stem from induced mitochondrial dysfunction and ferroptosis. In contrast, n-NPs predominantly stimulated innate immune responses, influencing salivary secretion and modulating the complement and coagulation cascades. Furthermore, in vitro tests on clam immune cells confirmed that internalized p-NPs triggered alterations in mitochondrial morphology, a decrease in membrane potential, and the initiation of ferroptosis. Conversely, n-NPs, to a certain extent, moderated the expression of genes related to immune responses, thus mitigating their adverse effects. Taken together, these findings indicate that the differential surface-charge-driven ferroptosis and mitochondrial dysfunction in clams play a critical role in the toxicity profile of NPs, providing an insightful reference for assessing the ecological toxicity associated with NPs.

Effects of polyethylene, polylactic acid, and tire particles on the sediment microbiome and metabolome at high and low temperatures.

Global warming has led to a high incidence of extreme heat events, and the frequent occurrence of extreme heat events has had extensive and far-reaching impacts on wetland ecosystems. The widespread distribution of plastics in the environment, including polyethylene (PE), polylactic acid (PLA), and tire particles (TPs), has caused various environmental problems. Here, high-throughput sequencing techniques and metabolomics were used for the first time to investigate the effects of three popular microplastic types: PE, PLA, and TP, on the sediment microbiome and the metabolome at both temperatures. The microplastics were incorporated into the sediment at a concentration of 3% by weight of the dry sediment (wt/wt), to reflect environmentally relevant conditions. Sediment enzymatic activity and physicochemical properties were co-regulated by both temperatures and microplastics producing significant differences compared to controls. PE and PLA particles inhibited bacterial diversity at low temperatures and promoted bacterial diversity at high temperatures, and TP particles promoted both at both temperatures. For bacterial richness, only PLA showed inhibition at low temperature; all other treatments showed promotion. PE, PLA, and TP microplastics changed the community structure of sediment bacteria, forming two clusters at low and high temperatures. Furthermore, PE, PLA, and TP changed the sediment metabolic profiles, producing differential metabolites such as lipids and molecules, organic heterocyclic compounds, and organic acids and their derivatives, especially TP had the most significant effect. These findings contribute to a more comprehensive understanding of the potential impact of microplastic contamination.IMPORTANCEIn this study, we added 3% (wt/wt) microplastic particles, including polyethylene, polylactic acid, and tire particles, to natural sediments under simulated laboratory conditions. Subsequently, we simulated the sediment microbial and ecosystem responses under different temperature conditions by incubating them for 60 days at 15°C and 35°C, respectively. After synthesizing these results, our study strongly suggests that the presence of microplastics in sediment ecosystems and exposure under different temperature conditions may have profound effects on soil microbial communities, enzyme activities, and metabolite profiles. This is important for understanding the potential hazards of microplastic contamination on terrestrial ecosystems and for developing relevant environmental management strategies.

Polystyrene microplastics exposure aggravates acute liver injury by promoting Kupffer cell pyroptosis.

OBJECTIVE: To investigate the long-term effects of polystyrene (PS) exposure on acute liver injury. METHODS: The carbon tetrachloride-induced acute injury mouse model was subjected to long-term PS exposure. Pyroptosis was inhibited by knocking out Gsdmd in mice or treating with the Gsdmd inhibitor necrosulfonamide (NSA) to evaluate the effect of PS on liver injury. Kupffer cells were used as a cellular model to examine the effects of PS on cell pyroptosis, lactate dehydrogenase release rate, structural integrity (propidium iodide staining), and inflammatory factor levels. RESULTS: In mice, PS exposure exacerbated acute liver injury, which was mitigated upon Gsdmd knockout (KO) or NSA treatment along with the downregulation of tissue inflammatory response. In vitro studies demonstrated that PS promoted Kupffer cell pyroptosis, which was suppressed upon Gsdmd KO or NSA treatment along with the alleviation of inflammation. CONCLUSION: These results suggest that long-term PS exposure exacerbates acute liver injury by promoting Kupffer cell pyroptosis, which is one of the hepatotoxic mechanisms of PS.

Multigenerational effects of elevated temperature on host-microbiota interactions in the marine water flea Diaphanosoma celebensis exposed to micro- and nanoplastics.

Rising ocean temperatures are driving unprecedented changes in global marine ecosystems. Meanwhile, there is growing concern about microplastic and nanoplastic (MNP) contamination, which can endanger marine organisms. Increasing ocean warming (OW) and plastic pollution inevitably cause marine organisms to interact with MNPs, but relevant studies remain sparse. Here, we investigated the interplay between ocean warming and MNP in the marine water flea Diaphanosoma celebensis. We found that combined exposure to MNPs and OW induced reproductive failure in the F2 generation. In particular, the combined effects of OW and MNPs on the F2 generation were associated with key genes related to reproduction and stress response. Moreover, populations of predatory bacteria were significantly larger under OW and MNP conditions during F2 generations, suggesting a potential link between altered microbiota and host fitness. These results were supported by a host transcriptome and microbiota interaction analysis. This research sheds light on the complex interplay between environmental stressors, their multigenerational effects on marine organisms, and the function of the microbiome.

Effects of combined exposure to polystyrene microplastics and 17α-Methyltestosterone on the reproductive system of zebrafish.

Polystyrene microplastics (PS-MPs) are important carriers of pollutants in water. 17α-Methyltestosterone (MT) is a synthetic environmental endocrine disrupting chemical (EDC) with androgenic effects. To study the effects of PS-MPs and MT on zebrafish reproductive systems, zebrafish were exposed to 0 or 50 ng L-1 MT, 0.5 mg∙L-1 PS-MPs, or 50 ng∙L-1 MT + 0.5 mg∙L-1 PS-MPs for 21 d. The results showed that the different exposure reagents caused varying degrees of damage to the reproductive systems in zebrafish, with the extent of damage increasing as the exposure duration increased. Histological analysis of the gonads revealed that the ratio of mature oocytes and mature spermatozoa in the gonad decreased gradually with increased exposure time, with the ratio being Control > PS-MPs > MT > MT + PS-MPs in decreasing order. The results of quantitative real-time PCR (qRT‒PCR) showed that in female fish treated for 7 d, the expression of cyp11a mRNA was significantly reduced in all three treatment groups(MT, PS-MPs, and MT + PS-MPs), while in the group treated for 14 d with MT + PS-MPs, the expression of cyp19a1a and StAR mRNA was significantly increased. In male fish exposed for 21 d, the expression of cyp11a, cyp17a1, cyp19a1a, StAR, 3ß-HSD, and 17ß-HSD3 mRNA was significantly decreased in MT + PS-MPs. ELISA results showed that after 14 d of exposure, the levels of E2, LH, and FSH in the ovaries of female fish were significantly reduced in all three treatment groups. Similarly, the levels of T, E2, LH, and FSH in the testis of male fish were significantly reduced after 14 d of exposure to PS-MPs and MT + PS-MPs. Offspring of zebrafish exposed to MT and MT + PS-MPs exhibited delayed incubation time and slow development. The cross-generational toxicity of PS-MPs themselves may be negligible, but it can exacerbate the toxicity of MT, making the cross-generational effects more pronounced in the offspring, causing offspring mortality and malformations. Offspring of zebrafish exposed to MT and MT + PS-MPs exhibited delayed incubation time and slow development. In addition, MT caused malformations such as pericardial edema, yolk cysts, and spinal deformities in zebrafish during the incubation period.

Effect of microplastics on urban wastewater disinfection and impact on effluent reuse: Sunlight/H2O2 vs solar photo-Fenton at neutral pH.

The interference of three types of microplastics (MPs) on the inactivation of Escherichia coli (E. coli) by advanced oxidation processes (AOPs) (namely, sunlight/H2O2 and solar photo-Fenton (SPF) with Ethylenediamine-N,N'-disuccinic acid (EDDS)), in real secondary treated urban wastewater was investigated for the first time. Inactivation by sunlight/H2O2 treatment decreased as MPs concentration and H2O2 dose were increased. Noteworthy, an opposite behaviour was observed for SPF process where inactivation increased as MPs concentration was increased. Biofilm formation and microbial attachment on surfaces of post-treated MPs were observed on polyethylene (PE) and polyvinyl chloride (PVC) MPs by field emission scanning electron microscopy. In presence of PE MPs, a complete inactivation of E. Coli was achieved by SPF with EDDS (Fe:EDDS = 1:2) after 90 min treatment unlike of sunlight/H2O2 treatment (∼4.0 log reduction, 40 mg/L H2O2 dose, 90 min treatment). The lower efficiency of sunlight/H2O2 process could be attributed to the blocking/scattering effect of MPs on sunlight, which finally reduced the intracellular photo Fenton effect. A reduced E. coli regrowth was observed in presence of MPs. SPF (Fe:EDDS = 1:1) with PE MPs was less effective in controlling bacterial regrowth (∼120 CFU/100 mL) than sunlight/H2O2 (∼10 CFU/100 mL) after 48 h of post-treatment. These results provide useful information about possible interference of MPs on urban wastewater disinfection by solar driven AOPs and possible implications for effluent reuse.

A meta-analysis-based adverse outcome pathway for the male reproductive toxicity induced by microplastics and nanoplastics in mammals.

The male reproductive toxicity of microplastics (MPs) and nanoplastics (NPs) has attracted great attention, but the latent mechanisms remain fragmented. This review performed the adverse outcome pathway (AOP) analysis and meta-analysis in 39 relevant studies, with the AOP analysis to reveal the cause-and-effect relationships of MPs/NPs-induced male reproductive toxicity and the meta-analysis to quantify the toxic effects. In the AOP framework, increased reactive oxygen species (ROS) is the molecular initiating event (MIE), which triggered several key events (KEs) at different levels. At the cellular level, the KEs included oxidative stress, mitochondrial dysfunction, sperm DNA damage, endoplasmic reticulum stress, apoptosis and autophagy of testicular cells, repressed expression of steroidogenic enzymes and steroidogenic acute regulatory protein, disrupted hypothalamic-pituitary-testicular (HPT) axis, and gut microbiota alteration. These KEs further induced the reduction of testosterone, impaired blood-testis barrier (BTB), testicular inflammation, and impaired spermatogenesis at tissue/organ levels. Ultimately, decreased sperm quality or quantity was noted and proved by meta-analysis, which demonstrated that MPs/NPs led to a decrease of 5.99 million/mL in sperm concentration, 14.62% in sperm motility, and 23.56% in sperm viability, while causing an increase of 10.65% in sperm abnormality rate. Overall, this is the first AOP for MPs/NPs-mediated male reproductive toxicity in mammals. The innovative integration of meta-analysis into the AOP analysis increases the rigorism of the results.

Response strategies of stem/leaves endophyte communities to nano-plastics regulate growth performance of submerged macrophytes.

Research on the toxicity effects of nano-plastics on submerged macrophytes has been increasing over the past several years. However, how the endophytic bacteria of submerged macrophytes respond to nano-plastics remains unknown, although they have been widely shown to help terrestrial plants cope with various environmental stressors. Here, a microcosm experiment was performed to unravel the effects of high concentration of nano-plastics (20 mg/L) on three submerged macrophyte (Vallisneria natans, Potamogeton maackianus, Myriophyllum spicatum) and their endophytic bacterial communities. Results indicated that nano-plastics induced antioxidative stress in plants, but significantly reduction in relative growth rate (RGR) only occurred in V. natans (from 0.0034 to -0.0029 day-1), accompanied by change in the stem/leaves endophyte community composition. Further analysis suggested nano-plastics caused a reduction in environmental nutrient availability and the proportion of positive interactions between endophyte communities (43%), resulting in the lowest RGR of V. natans. In contrast, endophytes may help P. maackianus and M. spicatum cope with nano-plastic stress by increasing the proportion of positive correlations among communities (70% and 75%), leaving their RGR unaffected. Collectively, our study elucidates the species-specific response strategies of submerged macrophyte-endophyte to nano-plastics, which helps to reveal the different phytoremediation potential of submerged macrophytes against nano-plastic pollution.

Exploring the combined interplays: Effects of cypermethrin and microplastic exposure on the survival and antioxidant physiology of Astacus leptodactylus.

Plastic waste and micro/nanoplastic particles pose a significant global environmental challenge, along with concerns surrounding certain pesticides' impact on aquatic organisms. This study investigated the effects of microplastic particles (MPPs) and cypermethrin (CYP) on crayfish, focusing on biochemical indices, lipid peroxidation, oxidative stress, hematological changes, and histopathological damage. After determining the LC50-96 h value (4.162 µg/L), crayfish were exposed to sub-lethal concentrations of CYP (1.00 ppb (20%) and 2.00 ppb (50%)) and fed a diet containing 100 mg/kg MPPs for 60 days. Hemolymph transfusion and histopathological examinations of the hepatopancreas were conducted. The results showed significant alterations in crayfish. Total protein levels decreased, indicating protein breakdown to counteract contaminants, while total cholesterol and triglyceride levels declined, suggesting impaired metabolism. Glucose levels increased in response to chemical stress. The decline in total antioxidant capacity highlighted the impact of prolonged xenobiotic exposure and oxidative stress, while increased CAT, SOD, and MDA activities helped mitigate oxidative stress and maintain cellular homeostasis. The elevated total hemocyte count, particularly in semi-granular cells, suggests their active involvement in the detoxification process. Further research is needed to fully understand the implications of these effects.

Phytotoxic effects of polyethylene microplastics combined with cadmium on the photosynthetic performance of maize (Zea mays L.).

Microplastics (MPs) and cadmium (Cd) has attracted increasing attention due to their combined toxicity to terrestrial vegetation. Photosynthesis which utilizes light energy to synthesize organic substances is crucial for crop production. However, the plant photosynthetic response to the joint toxicity of MPs and Cd is still unknown. Here, we studied the effects of polyethylene (PE) MPs on the photosynthetic performance of two maize cultivars Xianyu 335 (XY) and Zhengdan 958 (ZD) grown in a Cd contaminated soil. Results showed that the leaf Cd concentration in XY and ZD reached 26.1 and 31.9 µg g-1, respectively. PE-MPs did not influence the leaf Cd content, but posed direct and negative effects on photosynthesis by increasing the malondialdehyde content, reducing the chlorophyll content, inhibiting photosynthetic capacity, disrupting the PSII donor side, blocking electron transfer in different photosystems, and suppressing the oxidation and reduction states of PSI. Transcriptomic analysis revealed that the inhibitory effect of combined PE-MPs and Cd on maize photosynthesis was attributed to suppressed expression of the genes encoding PSII, PSI, F-type ATPase, cytochrome b6/f complex, and electron transport between PSII and PSI. Using WGCNA, we identified a MEturquoise module highly correlated with photosynthetic traits. Hub genes bridging carbohydrate metabolism, amino acid metabolism, lipid metabolism, and translation provided the molecular mechanisms of PE-MPs and Cd tolerance in maize plants. The comprehensive information on the phytotoxicity mechanisms of Cd stress in the presence or absence of PE-MPs on the photosynthesis of maize is helpful for cloning Cd and PE-MP resistance genes in the future.

Effects of microplastics on seed germination and seedling physiological characteristics of Spinacia oleracea under alkali stress.

Microplastics, a type of new environmental pollutant, have received much attention for their negative effects on organisms and environment. We examined the effects of microplastics on seed germination and seedling physiological characteristics of spinach (Spinacia oleracea) under alkali stress, taking polystyrene microspheres with a diameter of 100 nm (200, 400, 800, 1600 mg·L-1) as the microplastic treatment, and mixed NaHCO3 and Na2CO3 as alkaline salt solution (5, 10, 20, 40 mmol·L-1) according to the molar ratio of 1:1. The results showed that the presence of MPs (≥400 mg·L-1) inhibited seed germination, and that the length of roots and shoots increased at low while decreased at high concentration of MPs. Different concentrations of alkali alone could inhibit seed germination, root and bud elongation. With the increases of MPs concentration, SOD activity of spinach seedlings gradually decreased, while POD activity firstly increased and then decreased, and chlorophyll content increased at low concentration (200 mg·L-1) and decreased significantly at medium and high concentration (≥400 mg·L-1). Different alkali stresses reduced chlorophyll content of spinach seedlings, and the effects on SOD and POD were 'promotion at low concentration and inhibition at high'. In the treatments of microplastics (200, 800 mg·L-1) and alkali (5, 20 mmol·L-1) combined exposure, germination of spinach seeds was inhibited, and chlorophyll content decreased. The activities of SOD and POD in spinach seedlings were reduced under the combined exposure except the treatment of 200 mg·L-1 MPs and 5 mmol·L-1 alkali. Compared to the alkali stress, the combination of low concentration of MPs (200 mg·L-1) and alkali could improve germination rate, germination index, germination vigor and vigor index of seeds, and significantly promoted the elongation of roots and shoots, while the addition of high concentration of MPs (800 mg·L-1) reduced the germination rate, germination index, germination vigor and vigor index of seeds and inhibited the growth of roots and buds. The different concentrations of combined exposure inhibited the activities of SOD and POD and decreased the content of chlorophyll in spinach seedlings.