Puslaidininkinių nanodalelių toksikologinis potencialas ir poveikio mechanizmai žuvims ankstyvajame jų vystymesi

The dissertation was prepared by Živilė Jurgelėnė at the Nature Research Centre during 2014–2018. The thesis addresses the toxicological potential of carboxylated CdSe/ZnS quantum dots and Cd single, quantum dots stability, their accumulation, penetration, distribution and explains the mechanisms of quantum dots impact to fish in early development stages. In this study, carboxylated quantum dots (4 nM) were not found to affect mortality of rainbow trout embryos, but they were found to cause mortality of larvae during both short- and long-term experiments. In contrast, mortality rates of embryos and larvae increased with increasing duration of exposure to Cd (2 µg/L). In many cases, alterations in biological parameters (respiration, growth, development and behaviour) of test-organisms were related to the duration of exposure to quantum dots and Cd. It was found, that tested quantum dots were chemically stable in the incubation water, because the metals did not release from quantum dots structure and did not cause metallothionein induction. However, quantum dots formed aggregates and agglomerates. For the first time was shown that quantum dots did not penetrate into the embryos but damage the chorion integrity. Meanwhile, quantum dots accumulated and distributed in larvae gills region. Results of fish toxicity experiments with metals and environmental organic and inorganic nano- and micro-scale materials and induction of metallothionein in tissues of fish larvae allow us to presume that the impact of chemically stable quantum dots on test-organisms is of mechanical nature

Biological effects of multimetal (Ni, Cd, Pb, Cu, Cr, Zn) mixture in rainbow trout Oncorhynchus mykiss: Laboratory exposure and recovery study

The present study tested the biological consequences of exposure to a multimetal mixture as a multiple chemical stressor on Oncorhynchus mykiss at molecular, cellular, physiological and whole-organism levels and on biomarker responses of this fish during the depuration period. To represent environmentally relevant multiple chemical stressors, in our study, we used the mixture of Zn, Cu, Ni, Cr, Pb and Cd at the concentrations corresponding to Maximum-Permissible-Concentrations (MPCs) acceptable for the EU inland waters. This study was undertaken with a view to elucidate if changes in the MPC of the test mixture components (Ni, Pb, Cd) could cause significantly different biomarker responses in O. mykiss from those previously determined in the carnivorous and omnivorous fishes exposed to the mixture of the same metals but at different MPCs of Ni, Pb and Cd. This study has revealed that exposure to mixtures of metals at MPC produces genotoxic effects in fish blood erythrocytes and a lethargic effect on O. mykiss behaviour, and, also, significantly increases the levels of Cd, Cr and Ni accumulated in the gills tissue. O. mykiss successfully depurated Cr and Ni in less than 28 days, however, the level of Cd decreased by only approximately 40% over the same period. A significant capacity of O. mykiss to restore its DNA integrity (Comet assay) after exposure to metal mixtures was revealed. However, the 28-day recovery period proved to be insufficiently long for erythrocytes with nuclear abnormalities to recover to the unexposed level. In conclusion, changes in the MPCs of Ni, Pb and Cd in the test mixture produce biological effects similar to those previously determined in S. salar, R. rutilus and P. fluviatilis exposed to the mixture of the same metals but at lower MPCs of Ni and Pb and at higher MPC of Cd

Interactions of semiconductor Cd-based quantum dots and Cd2+ with gut bacteria isolated from wild Salmo trutta fry

With the rapid development of nanotechnology, more and more nanoproducts are being released into the environment where they may both pose ecological risks and be toxic to living organisms. The ecotoxicological impact of quantum dots (QDs), a class of nanoparticles (NPs), on aquatic organisms is becoming an emerging issue, this due to their nano-specific properties, to the physico-chemical transformation in the environment and to the possible release of toxic metals from their structure such as Cd. Methods In this work, (i) spectroscopic measurements of commercially available Cd-based QDs (CdSe/ZnS-COOH) were made at various pH values (5.0 and 7.0) to study their interactions (at a concentration of 4 nm) with various strains of Gram-positive and Gram-negative gut bacteria after short-term exposure and (ii) the antibacterial efficacy of QDs and Cd2+ (at a concentration 0.09–3.56 mM) against gut bacteria isolated from wild freshwater Salmo trutta fry was studied at different temperatures (15 °C and 25 °C) and pH values (5.0 and 7.0) by applying a well-established disc diffusion assay