Chronic effects of nano and microplastics on reproduction and development of marine copepod Tigriopus japonicus

Modeling the Vertical Transport of Copepod Fecal Particles under Nano/Microplastic Exposure

Nano- and microplastics (NMPs) may significantly impact the marine carbon cycle, and fecal pellets produced by the copepods are crucial for vertical carbon transport. In this study, we investigated the effects of NMP size, concentration, and diatom supply on the production and settling of fecal pellets by the marine copepod Parvocalanus crassirostris. By employing an aggregation-induced emission fluorescence imaging technique, we visualized the distribution of NMPs in fecal pellets, measured their size and production rate, and developed a fluid dynamic model to simulate the settling process of fecal pellets in the water column. Our results indicated that NPs and MPs exhibited uniform and nonuniform distributions in the produced fecal materials, respectively. NMPs reduced both the size and integrity of copepod fecal pellets. Copepods ingested MPs in the absence of diatoms, but exposure to 5000 μg/L of NMPs decreased the fecal pellet production by 52% in the presence of diatoms due to feeding selectivity. The sinking rates of fecal pellets of varying sizes, as obtained from modeling simulations, ranged from 10.9 to 103.1 m/day. When the proportion of participating polystyrene (PS) reached 50%, the sinking velocity decreased by 34%. Our study provides new insights into the vertical transport of copepod fecal pellets under NMP pollution.

Combined effects of polymethylmethacrylate microplastics with arsenic and copper on the euryhaline rotifer Proales similis

Aquatic organisms are typically exposed to chemical mixtures, including microplastics and metal(loid)s. However, most research has primarily focused on the toxicity of individual chemicals, potentially overestimating their risks to aquatic life. This study examined the combined effects of polymethylmethacrylate microplastics (PMMA-MPs) with As and Cu at environmentally relevant concentrations on the euryhaline rotifer Proales similis. The 48-h EC50 of PMMA-MPs (1.5-11.5 μm) was determined using concentrations from 1.0 to 100 mg/L. These concentrations were then combined with 0.41 mg/L As or 0.034 mg/L Cu. The combined effects of PMMA-MPs (0.031-1.0 mg/L) with As (0.025-0.2 mg/L) and Cu (0.0025-0.02 mg/L) at environmental concentrations were assessed through five-day chronic toxicity reproductive tests. The population growth rate was the endpoint for both acute and chronic testing. The EC50 of PMMA-MPs for P. similis was 44.0 mg/L, but this value significantly decreased when PMMA-MPs were co-exposed with the tested metal(loid)s. The tested mixtures of PMMA-MPs with As and Cu reduced growth rates by 13 - 48 % and 11 - 35 %, respectively, compared to the individual exposure to each chemical. This indicates that PMMA-MPs alter the toxic behavior of these metal(loid)s and vice versa. The present findings reveal that the combination of environmentally relevant concentrations of MPs (modeled as PMMA-MPs) with As and Cu can induce synergistic effects in marine rotifers. These results highlight the importance of investigating pollution in realistic scenarios that many aquatic invertebrates face.

Toxicity comparison of polylactic acid and polyethylene microplastics co-exposed with methylmercury on Daphnia magna

The prevalence of microplastics (MPs) in aquatic ecosystems has become a significant environmental concern due to their persistence and potential toxicity. Although bioplastics, such as polylactic acid (PLA), are promoted as eco-friendly alternatives to conventional plastics, their toxicity remains poorly understood. This study compares the toxicity and pollutant vector roles of polar PLA-derived bio-microplastics (bio-MPs) with apolar low-density polyethylene (LDPE) MPs, both individually and in combination with methylmercury (MeHg), in Daphnia magna. PLA bio-MPs, both alone and in combination with MeHg, significantly reduced survival rates and reproduction while inducing oxidative stress. Additionally, PLA bio-MPs increased Hg accumulation and negatively impacted acetylcholinesterase activity and vitellogenin gene expression compared to LDPE MPs. The findings of this study suggest that PLA bio-MPs, despite being in vivo biodegradable, may pose similar or even greater environmental risks than fossil fuel-based MPs, particularly due to their potential to enhance the bioaccumulation and toxicity of coexisting pollutants.

Teratological, neurochemical and histomorphic changes in the limbic areas of F1 mice progeny due to co-parental polystyrene nanoplastic exposure

In the present study, co-parental exposure to polystyrene nanoplastics (PS-NPs) elicits profound teratological impacts, including skeletal and visceral malformations, post-natal effects on neonatal growth and neurobehavioral development in F1 progeny. A comprehensive investigation was conducted on Swiss albino mice fetuses, neonates (PND 1-21) and adult mice offsprings (PND 60) following parental exposure during spermatogenesis and oogenesis period, as well as continued maternal exposure during gestation and weaning. The parental mice were administered PS-NPs via oral gavage at low dose (0.2 mg/kg/day) and high dose (1 mg/kg/day). Both male and female parental mice were exposed to PS-NPs for 60 days and 14 days, respectively before mating. After the mating, the pregnant female mice continued to receive PS-NPs treatment during the gestation, till the subsequent weaning period. Our findings revealed that PS-NPs led to significant reductions in growth, and heightened skeletal and visceral anomalies in developing fetuses. Exposure further impaired reflexes in neonatal mice such as grasping, surface righting and negative geotaxis. Moreover, the adult progeny also exhibited learning impairments. Neurodevelopmental assessment unveiled alterations in neurotransmitter levels, antioxidant enzyme activities, and structural changes in key limbic areas such as the cortex, hippocampus, and hypothalamus of adult mice offspring. These alterations included increased vacuolization, vascular dilation, and reduced pyramidal neurons in the hippocampus. Thus, this transgenerational study underscores the detrimental effects of PS-NPs on both prenatal and postnatal development, emphasizing teratological and enduring neurological consequences in the limbic regions of F1 progeny mice brains.

Phenotypic and Gene Expression Alterations in Aquatic Organisms Exposed to Microplastics

The use of plastics, valued for its affordability, durability, and convenience, has grown significantly with the advancement of industry. Paradoxically, these very properties of plastics have also led to significant environmental challenges. Plastics are highly resistant to decomposition, resulting in their accumulation on land, where they eventually enter aquatic environments, due to natural processes or human activities. Among these plastics, microplastics, which are tiny plastic particles, are particularly concerning when they enter aquatic ecosystems, including rivers and seas. Their small size makes them easily ingestible by aquatic organisms, either by mistake or through natural feeding behaviors, which poses serious risks. Moreover, microplastics readily adsorb other pollutants present in aquatic environments, creating pollutant complexes that can have a synergistic impact, magnifying their harmful effects compared to microplastics or pollutants acting alone. As a result, extensive research has focused on understanding the effects of microplastics on aquatic organisms. Numerous studies have demonstrated that aquatic organisms exposed to microplastics, either alone or in combination with other pollutants, exhibit abnormal hatching, development, and growth. Additionally, many genes, particularly those associated with the antioxidant system, display abnormal expression patterns in these conditions. In this review, we examine these impacts, by discussing specific studies that explore changes in phenotype and gene expression in aquatic organisms exposed to microplastics, both independently and in combination with adsorbed pollutants.

Manifestation of polystyrene microplastic accumulation in brain with emphasis on morphometric and histopathological changes in limbic areas of Swiss albino mice

The widespread problem of microplastic (MP) contamination is becoming a major threat to the globe. Although most of the research to date has concentrated on the physiological impacts of MPs exposure, a relatively new field of study is beginning to examine its effects on the behaviour and limbic regions of the brain. In this study, exposure to polystyrene MPs (PS-MPs) for acute and sub-chronic durations negatively affected cognition and induced anxiety-like behaviour in mice. PS-MPs were detected in vital organs of mice, including the brain, which induced neurobehavioural and pathological changes in the limbic system. Furthermore, morphometric analysis revealed a significant decrease in the total cell count in the Dentate Gyrus (DG) and Cornu Ammonis (CA) regions of the hippocampus. Signs of neuronal injury and dystrophic changes were observed in the cortex, amygdala, and hypothalamus, potentially affecting anxiety and fear responses. Our study thus provides insight into the effect of PS-MPs on the neurobiology of the brain's limbic system and related behavioural alterations.

Microplastic ingestion induces energy loss on the copepod Tigriopus koreanus

In marine environments, exposure to microplastics threaten various organisms. A large portion of MPs may be bioavailable to copepods, and ingesting MPs has been reported to induce various adverse effects, including increased mortality, developmental retardation, and decreased reproduction. Adverse effects of MPs on these important processes of copepods may be induced by the obstructive effects of the ingested MPs on energy acquisition. However, few studies have explored the biological effects of MPs on copepods in terms of energy budgets. Therefore, we analyzed ATP (adenosine triphosphate) levels, enzyme activities, swimming distances, and excretion rates in marine copepods (Tigriopus koreanus) that have ingested polystyrene microplastics. Our results indicate that the ingestion of MPs may prevent adequate acquisition of nourishment and lead the copepods into a vicious circle in the respect to energetic burden. Our study provides biochemical evidence for a reduction in the energy budget of copepods due to MPs ingestion. Further, this study increases our understanding of the risks of microplastics, by providing advanced evidences of their effects on marine primary consumer.

Global Meta-Analysis and Review of Microplastic in Marine Copepods

Plastic pollution has spread through all parts of the marine environment, representing a significant threat to species and ecosystems. This study investigates the role of copepods as widespread microplastic reservoirs in the marine environment, by performing, a systematic review, meta-analysis, and semiquantitative analysis of scientific articles focusing on the interaction between copepods and microplastics under field conditions. Our findings indicate that despite uniformly low ingestion of microplastics across different marine layers and geographical areas, with a slight uptake in neustonic copepods, copepods might constitute one of the largest marine microplastic reservoirs. This phenomenon is attributed more to their vast abundance than to average microplastic ingestion values. In this article, a framework for data analysis and reporting is proposed to facilitate future large-scale evaluations and modelling of their extent and impact on plastic and carbon cycles. These insights place copepods at the forefront of the marine plastic cycle, possibly affecting plastic distribution, and bioavailability, thereby opening new pathways for understanding the complex dynamics of microplastics in marine ecosystems.

Microplastics and Oxidative Stress-Current Problems and Prospects

Microplastics (MPs) are plastic particles between 0.1 and 5000 µm in size that have attracted considerable attention from the scientific community and the general public, as they threaten the environment. Microplastics contribute to various harmful effects, including lipid peroxidation, DNA damage, activation of mitogen-activated protein kinase pathways, cell membrane breakages, mitochondrial dysfunction, lysosomal defects, inflammation, and apoptosis. They affect cells, tissues, organs, and overall health, potentially contributing to conditions like cancer and cardiovascular disease. They pose a significant danger due to their widespread occurrence in food. In recent years, information has emerged indicating that MPs can cause oxidative stress (OS), a known factor in accelerating the aging of organisms. This comprehensive evaluation exposed notable variability in the reported connection between MPs and OS. This work aims to provide a critical review of whether the harmfulness of plastic particles that constitute environmental contaminants may result from OS through a comprehensive analysis of recent research and existing scientific literature, as well as an assessment of the characteristics of MPs causing OS. Additionally, the article covers the analytical methodology used in this field. The conclusions of this review point to the necessity for further research into the effects of MPs on OS.

Electroactive properties of EABs in response to long-term exposure to polystyrene microplastics/nanoplastics and the underlying adaptive mechanisms

Given widespread presence of polystyrene (PS) microplastics/nanoplastics (MPs/NPs), the electroactive responses and adaptation mechanisms of electroactive biofilms (EABs) exposed long-term to PS-containing aquatic environments remain unclear. Therefore, this study investigated the impacts of PS MPs/NPs on electroactivity of EABs. Results found that EABs exhibited delayed formation upon initially exposure but displayed an increased maximum current density (Imax) after subsequent exposure for up to 55 days. Notably, EABs exposure to NH2PS NPs (EAB-NH2PSNPs) demonstrated a 50% higher Imax than the control, along with a 17.84% increase in viability and a 58.10% increase in biomass. The cytochrome c (c-Cyts) content in EAB-NH2PSNPs rose by 178.35%, benefiting the extracellular electron transfer (EET) of EABs. Moreover, bacterial community assembly indicated the relative abundance of electroactive bacteria increased to 87.56% in EAB-NH2PSNPs. The adaptability mechanisms of EABs under prolonged exposure to PS MPs/NPs predominantly operate by adjusting viability, EET, and bacterial community assembly, which were further confirmed a positive correlation with Imax through structural equation model. These findings provide deeper insights into long-term effects and mechanisms of MPs/NPs on the electroactive properties of EABs and even functional microorganisms in aquatic ecosystems.

Physiological responses and altered halocarbon production in Phaeodactylum tricornutum after exposure to polystyrene microplastics

Oceanic emissions are a major source of atmospheric, very short-lived, ozone-depleting, brominated substances. These substances can be produced by marine microalgae, estimates of their current and future emissions are imperfect, because the processes by which marine microalgae respond to environmental changes are rarely account for environmental pollutants. Here, concurrent measurements of the potential effects of polystyrene (PS) microplastics with concentrations of 25-100 mg/L on the growth of Phaeodactylum tricornutum and their volatile halocarbons (VHCs) production were made over a 20-day culture period. The maximum inhibition rates (IR) due to 0.1 µm and 0.5 µm PS microplastics on cell density were 40.11 % and 32.87 %, on Chl a content were 25.89 % and 20.73 %, and on Fv/Fm were 9.74 % and 9.00 %, respectively. All IR showed dose-dependent effects with maxima occurring in the logarithmic phase. However, in the stationary phase, P. tricornutum exposed to PS microplastics exhibited improved attributes. Enhanced biogenesis of VHCs was induced by the excess reactive oxygen species in algal cells due to microplastics exposure, and their production rates were higher in the logarithmic phase than stationary phase. This represents that oxidative stress to cells plays a dominant role in determining the release of CHBrCl2, CHBr2Cl, and CHBr3. Hence, we suggest that the widespread microplastics in the ocean may be partly responsible for the increase in the emission of VHCs by marine phytoplankton, thereby affecting the ozone layer recovery in the future.

Polytetrafluorethylene microplastic particles mediated oxidative stress, inflammation, and intracellular signaling pathway alteration in human derived cell lines

Microplastics (MPs) are now widely distributed across the aerial, terrestrial, and aquatic environments. Thus, exposure to MPs via the oral, inhalation, or dermal routes is inevitable. Polytetrafluoroethylene (PTFE)-MPs is mainly used for manufacturing nonstick cookware, semiconductors, and medical devices; however, their toxicity has been rarely studied. In the present study, six different human cell lines, which are representative of tissues and cells that directly or indirectly come into contact with MPs, were exposed to two different sizes of irregular shape PTFE-MPs (with an average diameter of 6.0 or 31.7 μm). PTFE-MPs-mediated cytotoxicity, oxidative stress, and changes in proinflammatory cytokine production were then evaluated. We found that the PTFE-MPs did not induce cytotoxicity under any of the experimental conditions. However, PTFE-MPs (especially average diameter of 6.0 μm) induced nitric oxide and reactive oxygen species production in all the cell lines tested. Moreover, both sizes of PTFE-MPs increased the secretion of tumor necrosis factor alpha and interleukin-6 from the U937 macrophage cell line and the A549 lung epithelial cell line, respectively. In addition, PTFE-MPs activated the MAPK signaling pathways, especially the ERK pathway, in A549 and U937 cells, and in the THP-1 dendritic cell line. We also found that the expression of the NLRP3 inflammasome was reduced in the U937 and THP-1 cell lines following treatment with the PTFE-MPs sized 31.7 μm average diameter. Furthermore, expression of the apoptosis regulator, BCL2, was markedly increased in the A549 and U937 cell lines. Thus, although PTFE-MPs exert different effects on different cell types, our findings suggest that PTFE-MPs-associated toxicity may be specifically linked to the activation of the ERK pathway, which ultimately induces oxidative stress and inflammation.

Size matters either way: Differently-sized microplastics affect amphibian host and symbiotic microbiota discriminately

Concerns about the implications of microplastics (MPs) on aqueous animals have gained widespread attention. It has been postulated that the magnitude of MPs can influence its toxicity. However, little is known about how MPs toxicity changes with particle size. Amphibians are reliable bioindicators of ecosystem health due to their complex life cycles. In this study, we compared the influences of two sizes nonfunctionalized polystyrene microspheres (1 and 10 μm) on the metamorphosis of Asiatic toad (Bufo gargarizans). Acute exposure to MPs at high concentrations led to bioaccumulation in the digestive track and internal organs (i.e., liver and heart) of tadpoles. Long-term exposure to either size, at environmentally-related concentrations (1 and 4550 p/mL), led to growth and development delay in pro-metamorphic tadpoles. Remarkably, developmental plasticity mitigated these deleterious effects prior to the onset of metamorphic climax without compromising survival rate in later stages. MPs with a diameter of 10 μm dramatically altered the gut microbiota (e.g., abundance of Catabacter and Desulfovibrio) of pro-metamorphic tadpoles, whereas MPs with a diameter of 1 μm induced much more intensive transcriptional responses in the host tissues (e.g., upregulation of protein synthesis and mitochondrial energy metabolism, and downregulation of neural functions and cellular responses). Given that the two MPs sizes induced similar toxic outcomes, this suggests that their principal toxicity mechanisms are distinct. Small-sized MPs can travel easily across the intestinal mucosa and cause direct toxicity, while large-sized MPs accumulate in gut and affect the host by changing the homeostasis of digestive track. In conclusion, our findings indicate that MPs can affect the growth and development of amphibian larvae, but their developmental plasticity determines the ultimate detrimental effects. Multiple pathways of toxicity may contribute to the size-dependent toxicity of MPs. We anticipate that these findings will increase our understanding of the ecological effects of MPs.