Photoaging Elevated the Genotoxicity of Polystyrene Microplastics to Marine Mussel Mytilus trossulus (Gould, 1850).

Micro-sized particles of synthetic polymers (microplastics) are found in all parts of marine ecosystems. This fact requires intensive study of the degree of danger of such particles to the life activity of hydrobionts and needs additional research. It is evident that hydrobionts in the marine environment are exposed to microplastics modified by biotic and abiotic degradation. To assess the toxic potential of aging microplastic, comparative studies were conducted on the response of cytochemical and genotoxic markers in hemocytes of the mussel Mytilus trossulus (Gould, 1850) after exposure to pristine and photodegraded (UV irradiation) polystyrene microparticles (µPS). The results of cytochemical tests showed that UV-irradiated µPS strongly reduced metabolism and destabilized lysosome membranes compared to pristine µPS. Using a Comet assay, it was shown that the nuclear DNA of mussel hemocytes showed high sensitivity to exposure to both types of plastics. However, the level of DNA damage was significantly higher in mussels exposed to aging µPS. It is suggested that the mechanism of increased toxicity of photo-oxidized µPS is based on free-radical reactions induced by the UV irradiation of polymers. The risks of toxic effects will be determined by the level of physicochemical degradation of the polymer, which can significantly affect the mechanisms of toxicity.

Expanded Polystyrene-Debris-Induced Genotoxic Effect in Littoral Organisms.

Expanded polystyrene (EPS) is a major component of plastic debris in the environment, including coastal and littoral zones. EPS is widely used in various industries including fish farming and aquaculture, which poses a serious potential threat not only to cultured hydrobionts but also to all living organisms, including humans. This paper presents the results of experimental studies on the effects of EPS (0.024 m2/L) on marine mollusks Mytilus trossulus and Tegula rustica, which are typical inhabitants of the upper littoral of Peter the Great Bay (Sea of Japan), belonging to different systematic groups and differing in the type of nutrition. The results of biochemical marker analysis showed the development of oxidative stress processes. Thus, increasing malondialdehyde content relative to control values was registered in the digestive glands of M. trossulus and T. rustica. In the cells of the digestive glands of M. trossulus, integral antioxidant activity decreased more than 1.5 times compared with that of the control. The change in the concentration of protein carbonyls was unchanged in M. trossulus, whereas in T. rustica, there was a 1.5-fold increase. EPS exposure also resulted in significant DNA damage in the studied mollusks-the damage level increased 2.5-fold in M. trossulus and 1.5-fold in T. rustica relative to the control, indicating the genotoxic potential of EPS litters.

Dietary Exposure to Particles of Polytetrafluoroethylene (PTFE) and Polymethylmethacrylate (PMMA) Induces Different Responses in Periwinkles Littorina brevicula.

The marine and ocean water pollution with different-sized plastic waste poses a real threat to the lives of the next generations. Plastic, including microplastics, is found in all types of water bodies and in the organisms that live in them. However, given the chemical diversity of plastic particles, data on their toxicity are currently incomplete. Moreover, it is clear that different organisms, depending on their habitat and feeding habits, are at different risks from plastic particles. Therefore, we performed a series of experiments on feeding the gastropod scraping mollusk Littorina brevicula with two types of polymeric particles-polymethylmethacrylate (PMMA) and polytetrafluoroethylene (PTFE)-using a special feeding design. In the PMMA-exposed group, changes in gastrointestinal biochemical parameters such as increases in malondialdehyde (MDA) and protein carbonyls (PC) were detected, indicating the initiation of oxidative stress. Similarly, a comet assay showed an almost twofold increase in DNA damage in digestive gland cells compared to the control group. In mollusks fed with PTFE-containing food, no similar changes were recorded.

Zinc Oxide Nanoparticles Induce DNA Damage in Sand Dollar Scaphechinus mirabilis Sperm.

Products containing nanomaterials are becoming more and more common in everyday life. Zinc oxide nanoparticles (ZnO NPs), meanwhile, are among the most widely used NPs. However, their genotoxic effect on the germ products of marine organisms is poorly understood. Therefore, the effects of ZnO NPs and zinc ions (20, 50, 100, 200 µg/L) on the sperm of sand dollar Scaphechinus mirabilis were compared. Comet assay showed that both tested pollutants caused an increase in DNA damage to 6.57 ± 2.41 and 7.42 ± 0.88% DNA in the comet tail, for zinc ions and ZnO NPs, respectively. Additionally, a different pattern was shown by the increase in DNA damage, with increasing concentration of pollutants, in different experimental groups.

Exposure of adult sand dollars (Scaphechinus mirabilis) (Agassiz, 1864) to copper oxide nanoparticles induces gamete DNA damage.

The increase in the number of products containing nanoparticles (NPs) poses a real threat to the environment. Recently, more evidence has been added to predictive models about the presence of NPs in various natural and anthropogenic systems. The acute toxicity of most aquatic NPs has now been well documented. However, data such as the ecotoxicological significance of the long-lasting effects of NPs on the reproductive system and gamete quality of aquatic organisms are still relatively scarce. Therefore, a 10-day experiment was carried out on the sand dollar Scaphechinus mirabilis (Agassiz, 1864) exposed to low (20 and 40 µg/L) concentrations of copper oxide nanoparticles (CuO NPs). An accumulation of copper in tissues and a significant increase in lipid peroxidation product concentrations after exposure to NP were observed. A significant decrease in the fertilization rate was shown at 40 µg/L. No significant changes in embryonic or larval development were found. However, comet analysis results showed a significant increase in DNA damage in spermatozoa exposed to CuO NPs, which may further manifest as negative effects at later developmental stages or in subsequent generations.

Genotoxic Effects of Exposure to Water-Soluble Fraction of Diesel Fuel in Sand Dollar Scaphechinus mirabilis Gametes.

Pollution of marine areas with oil and oil products is steadily growing. As part of this connection, the study of the impact of petroleum hydrocarbons on marine hydrobionts is an urgent issue of modern ecotoxicology. In our study, the genotoxic effect of the water-soluble fraction of diesel fuel at different concentrations on the gametes of the sand dollar Scaphechinus mirabilis was evaluated. It was shown that during the incubation of sperm and eggs of a sand dollar in WAF with an oil hydrocarbon content of 1.32; 2.64; 5.37; 7.92 mg/L caused the destruction of the DNA molecule to varying degrees in both types of gametes. In addition, it has been shown that with an increase in the concentration of petroleum hydrocarbons in WAF, a large number of cells with a high level of DNA damage appear. The success of fertilization after exposure of gametes to a water-soluble extract of petroleum hydrocarbons was also evaluated. The relationship between an increase in the concentration of hydrocarbons in the tested solutions and a decrease in the level of fertilization is shown.

Genotoxicity of Paragonimus heterotremus Infection in a Rat Model of Simultaneous Pulmonary and Hepatic Paragonimiasis.

Parasites cause numerous health issues in humans, eventually leading to significant social and economic damage; however, the mechanisms of parasite-mediated pathogenesis are not well understood. Nevertheless, it is clearly evidenced that cancerogenic fluke-induced chronic inflammations and cancer are closely associated with oxidative stress. (1) Methods: The Paragonimus heterotremus infection's genotoxic potential was assessed in a rat model of simultaneous pulmonary and hepatic paragonimiasis by the alkaline version of single-cell gel electrophoresis (comet assay). Statistical analysis of comet parameters was based on the non-parametric Mann-Whitney U test. (2) Results: A clear and statistically significant increase in DNA damage was detected in the helminth-exposed group versus the control rats and the tissue areas adjacent to the parasite capsule versus remote ones; however, differences in DNA damage patterns between different tissues were not statistically significant. Infection resulted in up to 40% cells with DNA damage and an increased genetic damage index. (3) Conclusions: The data obtained contribute to understanding the pathogenesis mechanisms of paragonimiasis, suggesting oxidative stress as the most likely reason for DNA breaks; these findings allow us to consider P. heterotremus as a potentially cancerogenic species, and they are important for the monitoring and treatment of paragonimiasis.

Copper effect on the biomarker state of the Mizuhopecten yessoensis tissues in the prespawning period.

The aim of this study was to investigate the sensitivity of the marine scallop Mizuhopecten yessoensis to different copper concentrations (10 and 30 µgl-1) in the prespawning period. Reaction of the scallop to this effect was evaluated by a set of biomarkers, including general metabolism enzymes (acid and alkaline phosphatase activities - AcPase, ALP), and oxidative stress parameters (catalase antioxidant enzyme activity - CAT and levels of damage for DNA, lipids and proteins). Experiment results show that when copper is accumulated in tissues, enzyme activity changes are similar and have phasic character. The dynamics of these changes depends on the copper accumulation levels in tissues. Unlike enzyme reaction to copper accumulation, oxidative damage of biologic molecules changes in tissues in different ways. Copper enters into a scallop's organism, mainly through the gills, where there is a more expressed reaction of biomarkers compared to the digestive gland.

Accumulation and Tissue Distribution of Dinophysitoxin-1 and Dinophysitoxin-3 in the Mussel Crenomytilus grayanus Feeding on the Benthic Dinoflagellate Prorocentrum foraminosum.

A DTX-1-producing microalga, Prorocentrum foraminosum, from Peter the Great Bay, Sea of Japan, was fed to Gray's mussels, Crenomytilus grayanus, for 12 days. An increase in DTX-1 and 7-O-acyl-DTX-1 (DTX-3) was observed in the digestive gland, kidneys, and gills. The digestive gland accumulated 91-100% of DTX-1 + DTX-3; and kidneys and gills accumulated, up to 8.5% and 4.3%, respectively. The kidneys had a distinctive pattern of toxin accumulation where the concentration of DTX-1 did not grow significantly after the eighth day of feeding, indicating the potential of DTX-1 elimination. The digestive gland and gills predominantly accumulated DTX-1, with a dramatic increase between Days 8 and 12. The DTX-3 content was highest in the digestive gland. The composition of DTX-3 in the acyl groups was similar for the digestive gland and kidneys, and did not change during feeding. The total toxin uptake of mussels exceeded the total toxin content from ingested cells by 2.4 times, showing that toxins may have accumulated from the seawater. This assumption needs to be further proved. The muscle, gonads, and mantle remained free of toxins. No genotoxic effect was observed in the gills and digestive gland.