No abstract

Currently, silver nanoparticles (AgNPs) are frequently used in a wide range of medical and consumer products. Substantial usage of AgNPs is considered to create substantive risks to both the environment and the human health. Since there is increasing evidence that the main mechanism of toxicity of AgNPs relates to oxidative stress, in the current study we investigate oxidative stress-related biochemical parameters in myelin isolated from adult rat brain subjected to a low dose of AgNPs. Animals were exposed for 2 weeks to 0.2 mg/kg b.w. of small (10 nm) AgNPs stabilized in citrate buffer or silver citrate established as a control to compare the effects of particulate and ionic forms of silver. We observe enhanced peroxidation of lipids and decreased concentrations of protein and non-protein –SH groups in myelin membranes. Simultaneously, expression of superoxide dismutase, a free radical scavenger, is increased whereas the process of protein glutathionylation, being a cellular protective mechanism against irreversible oxidation, is found to be inefficient. Results indicate that oxidative stress-induced alterations in myelin membranes may be the cause of ultrastructural disturbances in myelin sheaths.

Silver nanoparticles, chemically neutral particles in the size range of 1-100 nm, express strong antimicrobial activity and therefore have a broad range of applications. The increased use of consumer products with nanosilver (nanoAg) may result in its release into the environment, and may particularly affect aquatic systems. The mechanisms of the harmful effects of nanoAg against aquatic organisms are unclear. Therefore, in the present study we investigate the pro-oxidative potential of these nanoparticles in experimentally exposed crayfish Orconectes limosus. Markers of oxidative stress and parameters of the antioxidant cell defense system such as total glutathione, glutathione reductase and the level of sulfhydryl groups were examined in the hepatopancreas of both sexes of O. limosus collected seasonally from Białe Lake (Poland) and subsequently exposed to nanoAg particles for 2 weeks. Exposure to nanoAg led to a high concentration-dependent increase in the rate of lipid peroxidation and a decrease of protein-bound SH groups which indicates protein oxidation. These markers of oxidative stress were accompanied by decreased levels of thiols and reduced activity of glutathione reductase. These results indicate a deficiency of reduced glutathione and suggest that the exposed organisms have less efficient antioxidative mechanisms available to counter ROS-mediated cellular stress. Furthermore, we find that confocal microscopy is of limited utility in monitoring the presence of silver nanoparticles in tissues of exposed crayfish.

This contribution presents new observations of the red swamp crayfish, Procambarus clarkii in Poland. The species was detected in Żerań Canal and Krasiński Garden in Warsaw (central Poland) where 5 and 2 individuals were collected respectively as well as in Dąbie Pond in Krakow (southern Poland) with total of 4 crayfish observed. These new sites are located approximately 500 km eastward (Warsaw) and 240-260 km northward (Krakow) from the nearest European sites where this species has been previously recognised (near Berlin, Germany, Egerszalók and Budapest, Hungary), thus are the furthest north-east records of the species in European open waters. It is likely that the examined stock originates from single introductions, however, presence of the juveniles caught in Warsaw suggests that the population found there may be breeding. The findings are discussed with available literature describing possible ways P. clarkii may use to colonize new habitats as well as the impact it has on the invaded ecosystems in general and native crayfish in particular.Keywords: Alien species / freshwater crustacean / ornamental pet trade / inland waters / Central Europe Résumé -Nouveaux signalements de l'écrevisse de Louisiane envahissante Procambarus clarkii (Girard, 1852) (Decapoda : Cambaridae) en Pologne. Cette contribution présente de nouvelles observations de l'écrevisse de Louisiane, Procambarus clarkii en Pologne. L'espèce a été détectée sur le Canal Żerań et le jardin Krasiński à Varsovie (centre de la Pologne) où 5 et 2 individus ont été prélevés respectivement ainsi que dans l'étang Dąbie à Cracovie (sud de la Pologne) avec au total 4 écrevisses observées. Ces nouveaux sites sont situés à environ 500 km à l'est (Varsovie) et 240-260 km au nord (Cracovie) des sites européens les plus proches où cette espèce a été précédemment reconnue (près de Berlin, Allemagne, et Budapest, Hongrie), ce qui en fait les plus au nord-est de l'Europe en eaux libres. Il est probable que le stock examiné provient d'introductions uniques, mais la présence de juvéniles capturés à Varsovie suggère que la population qui s'y trouve pourrait s'y reproduire. Les résultats sont discutés avec la littérature disponible décrivant les façons que P. clarkii peut utiliser pour coloniser de nouveaux habitats ainsi que l'impact qu'il a sur les écosystèmes envahis en général et les écrevisses indigènes en particulier.