The observation of starch digestion in blue mussel Mytilus galloprovincialis exposed to microplastic particles under varied food conditions

Plastic pollution and marine mussels: Unravelling disparities in research efforts, biological effects and influences of global warming

The ever-growing contamination of the environment by plastics is a major scientific and societal concern. Specifically, the study of microplastics (1 μm to 5 mm), nanoplastics (< 1 μm), and their leachates is a critical research area as they have the potential to cause detrimental effects, especially when they impact key ecological species. Marine mussels, as ecosystem engineers and filter feeders, are particularly vulnerable to this type of pollution. In this study, we reviewed the 106 articles that focus on the impacts of plastic pollution on marine mussels. First, we examined the research efforts in terms of plastic characteristics (size, polymer, shape, and leachates) and exposure conditions (concentration, duration, species, life stages, and internal factors), their disparities, and their environmental relevance. Then, we provided an overview of the effects of plastics on mussels at each organisational levels, from the smaller scales (molecular, cellular, tissue and organ impacts) to the organism level (functional, physiological, and behavioural impacts) as well as larger-scale implications (associated community impacts). We finally discussed the limited research available on multi-stressor studies involving plastics, particularly in relation to temperature stress. We identified temperature as an underestimated factor that could shape the impacts of plastics, and proposed a roadmap for future research to address their combined effects. This review also highlights the impact of plastic pollution on mussels at multiple levels and emphasises the strong disparities in research effort and the need for more holistic research, notably through the consideration of multiple stressors, with a specific focus on temperature which is likely to become an increasingly relevant forcing factor in an era of global warming. By identifying critical gaps in current knowledge, we advocate for more coordinated interdisciplinary and international collaborations and raise awareness of the need for environmental coherence in the choice and implementation of experimental protocols.

Microplastic exposure reduced the defecation rate, altered digestive enzyme activities, and caused histological and ultracellular changes in the midgut tissues of the ground beetle (Blaps polychresta)

Concerns about microplastic (MP) pollution in terrestrial systems are increasing. It is believed that the overall amount of MPs in the terrestrial system could be 4-23 times higher than that in the ocean. Agricultural ecosystems are among the most polluted areas with MPs. Terrestrial organisms such as ground beetles, will be more vulnerable to MPs in various agricultural soil types because they are common in garden and agricultural areas. Therefore, this work aims to assess for the first time the potential adverse effects of chronic exposure for 30 days of ground beetles to a field-realistic concentration of 2 % (w/w) of three different irregularly shaped MPs polymers: Polystyrene (PS), polyethylene terephthalate (PET), and polyamide 6 (PA; i.e., nylon 6) on their health. The results showed no effect on beetle survival; nevertheless, there was a decrease in beetle defecation rate, particularly in beetles exposed to PS-MPs, and a change in the activity of midgut digestive enzymes. The effects on digestive enzymes (amylase, protease, lipase, and α-glucosidase) were polymer and enzyme specific. Furthermore, histological and cytological studies demonstrated the decomposition of the midgut peritrophic membrane, as well as abnormally shaped nuclei, vacuolation, disordered microvilli, necrosis of goblet and columnar cells, and necrosis of mitochondria in midgut cells. Given the importance of ground beetles as predators in most agricultural and garden settings, the reported adverse impacts of MPs on their health may impact their existence and ecological functions.

High-density polyethylene microplastics in agricultural soil: Impact on microbes, enzymes, and carbon-nitrogen ratio

Microplastics (MPs), recognized as emerging pollutants, pose a significant threat to diverse organisms and have adverse effects on agricultural soil. High-density polyethylene (HDPE) holds a prominent position among prevalent forms of MPs. In the current investigations, the impact of HDPE was assessed at four different concentrations (0.25%, 0.5%, 0.75%, and 1.0%) on agricultural soil, microbial population, exoenzymes activities including amylase, cellulase, and invertase, and alteration in carbon-to-nitrogen (C/N) ratio. Both bacterial and fungal populations exhibited a non-concentration-dependent response to different concentrations of HDPE over time. In this study, we refer to the concentrations of 0.25%, 0.5%, 0.75%, and 1.0% as HT1, HT2, HT3, and HT4, respectively. Initial MP application significantly reduced bacterial colony counts for HT1, HT2, and HT4, while HT3 showed no significant change. On the 60th day, HT1 and HT3 exhibited a higher bacterial colony count compared to the control. On the other hand, fungal populations increased to maximum on day 1 but displayed no distinct time-dependent trend from days 15 to 60. Furthermore, enzyme activities decreased with increasing concentrations of MPs over an extended period. Molecular docking studies suggest that HDPE can hinder enzyme activity by forming hydrogen bonds with enzymes. The C/N ratio was found to be significantly higher in MP-treated soils on the 60th day relative to control, suggesting relatively slower degradation of carbon compounds in the MP-treated soils.

Correction: The observation of starch digestion in blue mussel Mytilus galloprovincialis exposed to microplastic particles under varied food conditions

[This corrects the article DOI: 10.1371/journal.pone.0253802.].

Different recovery patterns of the surviving bivalve Mytilus galloprovincialis based on transcriptome profiling exposed to spherical or fibrous polyethylene microplastics

Microplastics (MPs) are pervasive pollutants exuded from anthropogenic activities and ingested by animals in different ecosystems. This transcriptomic profiling study aimed to explore the impact of polyethylene MPs on Mytilus galloprovincialis, an ecologically significant bivalve species. The toxicity of two MPs types was found to result in increased cellular stress when exposed up to 14 days. Moreover, recovery mechanisms were also observed in progress. Mussels exhibited different gene expression patterns and molecular regulation in response to cellular reactive oxygen species (ROS) stress. The transcriptome analysis demonstrated a notable hindrance in cilia movement as MPs ingested through gills. Subsequent entry resulted in a significant disruption in the cytoskeletal organization, cellular projection, and cilia beat frequency. On day 4 (D4), signal transduction and activation of apoptosis evidenced the signs of toxic consequences. Mussels exposed to spherical MPs shown significant recovery on day 14 (D14), characterized by the upregulation of anti-apoptotic genes and antioxidant genes. The expression of P53 and BCL2 genes was pivotal in controlling the apoptotic process and promoting cell survival. Mussels exposed to fibrous MPs displayed a delayed cell survival effect. However, the elevated physiological stress due to fibrous MPs resulted in energy transfer by compensatory regulation of metabolic processes to expedite cellular recovery. These observations highlighted the intricate and varied reaction of cell survival mechanisms in mussels to recover toxicity. This study provides critical evidence of the ecotoxicological impacts of two different MPs and emphasizes the environmental risks they pose to aquatic ecosystems. Our conclusion highlights the detrimental effects of MPs on M. galloprovincialis and the need for more stringent regulations to protect marine ecosystems.

To what extent is blue mussels caging representative of microplastics in the natural environment?

Bivalves have gained prominence in active biomonitoring of microplastics (MPs) pollution. Nevertheless, critical questions persist regarding blue mussels' selectivity and representativeness of the presence of microplastics in the natural environments. In this current study, we explored short- and long-term exposure durations for caged mussels, aiming to establish the minimum period required for them to attain a steady-state in microplastics retention and investigate their selectivity in a real-world context. Various deployment periods (1, 2, and 5 weeks) were tested, with concurrent collection of MPs from the surrounding water each week. The results revealed a significant increase in ingested MPs, reaching a threshold of approximately 1.4 MPs per gram of wet weight during the fifth week of caging. The characteristics of MPs found in mussels exhibited some differences from those collected in the surrounding waters and were less temporally variable. Notably, the collected caged mussels demonstrated a tendency to retain smaller particles (<80 μm). This study underscores complex processes governing MPs selection in natural environments and the need for further research to gain a more comprehensive understanding of the conditions and suitability of mussels as bioindicators for assessing MPs pollution.

Nano- and Microplastics Migration from Plastic Food Packaging into Dairy Products: Impact on Nutrient Digestion, Absorption, and Metabolism

The ongoing use of plastic polymers to manufacture food packaging has raised concerns about the presence of nano- and microplastics (NMPs) in a variety of foods. This review provides the most recent data on NMPs' migration from plastic packaging into dairy products. Also discussed are the possible effects of NMPs on nutrient digestion, absorption, and metabolism. Different kinds of dairy products, including skimmed milk, whole liquid milk, powder milk, and infant formula milk, have been found to contain NMPs of various sizes, shapes, and concentrations. NMPs may interact with proteins, carbohydrates, and fats and have a detrimental impact on how well these nutrients are digested and absorbed by the body. The presence of NMPs in the gastrointestinal tract may impact how lipids, proteins, glucose, iron, and energy are metabolized, increasing the risk of developing various health conditions. In addition to NMPs, plastic oligomers released from food packaging material have been found to migrate to various foods and food simulants, though information regarding their effect on human health is limited. Viewpoints on potential directions for future studies on NMPs and their impact on nutrient digestion, absorption, and health are also presented in this review.

Evidence of microplastics release from polythene and paper cups exposed to hot and cold: A case study on the compromised kinetics of catalase

Microplastics (MPs) have become widespread in the modern world posing a hidden threat to the global environment. However, growing accumulation and devastating impact of MPs on human health and the environment have received least attention. In the current investigation, for the first time MPs have been identified which are released from the daily usable materials like polythene bags (PB) and paper cups (PC) in response to hot and cold water exposure at different time intervals. The impact of these MPs has been assessed on the major antioxidant enzyme, bovine liver catalase (BLC). The binding of MPs caused conformational changes in BLC by decreasing the α-helical content, which results in reduction of the enzymatic activity. Kinetics study revealed nearly ∼1.4-fold compromised catalytic efficiency of catalase in response to MPs. Nevertheless, hepatic catalase activity was also significantly decreased in presence of MPs. Further, materials like glass, porcelain, stainless steel, and high-grade plastics are discovered as greener alternatives to PB and PC.

Potential effects of natural aging process on the characteristics and toxicity of facial masks: A zebrafish-based study

The use of facial masks has increased and is therefore being recognized as a large source of environmental microplastics. Herein, we naturally aged disposable masks in a lake for eight weeks and compared the toxicity of mask-derived microplastics depending on the aging process using zebrafish (Danio rerio). Zebrafish were exposed to virgin and aged mask fragments (VF and AF, respectively) for eight weeks. The aging process induced cracks on the surface of mask fragments and chemical adsorption. Both VF and AFs damaged the zebrafish's liver, gills, and intestine and adversely affected their digestive ability, and their movement-aggression was decreased. These observations highlight the consequences of indiscriminately discarding masks or AFs following consumption. In conclusion, personal protective equipment waste in the environment should be appropriately managed to prevent negative impacts on aquatic organisms and, consequently, on humans via the food chain.

Effect of Microplastics on the Activity of Digestive and Oxidative-Stress-Related Enzymes in Peled Whitefish (Coregonus peled Gmelin) Larvae

Microplastics (MPs) are emergent pollutants in freshwater environments and may impact aquatic organisms, including those of nutritional value. The specific activities of digestive and antioxidant enzymes can be used as good bioindicators of the potential effects of MPs on fish in case of waterborne MP contamination. In this study, we used fluorescent polystyrene microplastics (PS-MPs) to analyze the alterations in enzyme activities in larvae of Coregonus peled Gmelin (peled or Northern whitefish), one of the most valuable commercial fish species of Siberia. Our results indicate that peled larvae can ingest 2 µm PS microspheres in a waterborne exposure model. A positive correlation (r_s = 0.956; p < 0.01) was found between MP concentration in water and the number of PS microspheres in fish guts, with no significant differences between 24 h and 6-day exposure groups. The ingestion of MPs caused alterations in digestive enzyme activity and antioxidant responses at the whole-body level. The presence of PS-MPs significantly stimulated (p < 0.05) the specific activity of α-Amylase and non-specific esterases in peled larvae after 24 h. However, a pronounced positive effect (p < 0.05) of MPs on the activity of pancreatic trypsine and bile salt-activated lipase was only found after 6 days of exposure compared to after 24 h. Intestinal membrane enzyme aminopeptidase N was also stimulated in the presence of PS-MPs after 6-day exposure. We also observed a significant increase in the specific activity of catalase in peled larvae after 6 days of exposure, which indicates the MP-induced modulation of oxidative stress. Taken together, these results highlight the potential impact of environmental MPs on northern commercial fish, their importance for estimating fish stocks, and the sustainability of freshwater ecosystems.

Trophic transfer of nanoplastics through a microalgae-crustacean-small yellow croaker food chain: Inhibition of digestive enzyme activity in fish

This study investigated the effects of nanoplastics on marine organisms via trophic transfer in the food chain. We designed a three-step food chain comprising microalga (Dunaliella salina), small crustaceans (Artemia franciscana), and fish (small yellow croakers; Larimichthys polyactis) and evaluated the effects of trophic transfer in marine organisms, as well as verified the possibility of nanoplastic transfer to humans via trophic transfer. Using amine-modified nanopolystyrene (nPS-NH₂) as a pollutant, we conducted both direct-exposure and trophic transfer experiments to determine how pollutants move through the food chain (D. salina → A. franciscana). Exposure of D. salina to nPS-NH₂, which was adsorbed on its cell wall, resulted in transfer to A. franciscana with alteration of gut permeability. Additionally, assessment of the adverse effects of nPS-NH₂ via a dietary pathway (three-step food chain) on the L. polyactis digestive system revealed that nanoplastics adsorbed to the cell wall of microalgae are gradually transferred to higher trophic level organisms, such as via food resources consumed by humans, inducing the inhibition of digestive enzyme activity (α-amylase). It indicates that human could eventually be exposed to nanoplastics and experience toxicity.