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.

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.

Using Heavy Metal Content and Lipid Peroxidation Indicators in the Tissues of the Mussel Crenomytilus grayanus for Pollution Assessment After Marine Environmental Remediation.

We examined the effects of environmental remediation on the heavy metal concentration and lipid peroxidation activity in the digestive gland and gills of the marine mussel Crenomytilus grayanus. Changes in heavy metal concentrations and lipid peroxidation biomarkers in the tissues of mussels collected at a contaminated site were compared with those obtained from a reference site. Prior to remediation the concentration of Pb, Cu, Cd, Fe and Zn and the levels of malondialdehyde, conjugated dienes and lipofuscin in mussels collected from the contaminated site were significantly increased compared with those obtained from the reference site. Three years after remediation, these parameters did not significantly exceed the reference site parameters, except Pb, whose concentration, though markedly decreased, yet was much higher than in tissues of mussels from the reference site.