The effectiveness of radiation-generated HO* radicals in initiating erythrocyte hemolysis in the presence of oxygen and under anaerobic conditions and prehemolytic structural changes in the plasma-erythrocyte membrane were studied. Under anaerobic conditions the efficacy of HO* radicals in induction of hemolysis was 16-fold lower than under air. In both conditions, hemolysis was the final consequence of changes of the erythrocyte membrane. Preceding hemolysis, the dominating process under anaerobic conditions was the aggregation of membrane proteins. The aggregates were principally formed by -S-S- bridges. A decrease in spectrin and protein of band 3 content suggests their participation in the formation of the aggregates. These processes were accompanied by changes in protein conformation determined by means of 4-maleimido-2,2,6,6-tetramethylpiperidine-N-oxyl (MSL) spin label attached to membrane proteins. Under anaerobic conditions, in the range of prehemolytical doses, the reaction of HO* with lipids caused a slight (10-16%) increase in fluidity of the lipid bilayer in its hydrophobic region with a lack of lipid peroxidation. However, in the presence of oxygen, hemolysis was preceded by intense lipid peroxidation and by profound changes in the conformation of membrane proteins. At the radiation dose that normally initiates hemolysis a slight aggregation of proteins was observed. Changes were not observed in particular protein fractions. It can be suggested the cross-linking induced by HO* radicals under anaerobic conditions and a lack of lipid peroxidation are the cause of a decrease in erythrocyte sensitivity to hemolysis. Contrary, under aerobic conditions, molecular oxygen suppresses cross-linking, catalysing further steps of protein and lipid oxidation, which accelerate hemolysis.

Human erythrocyte suspensions in an isotonic Na-phosphate buffer, pH 7.4, of hematocrit of 2% were exposed under air to gamma radiation at a dose rate of 2.2 kGy. Erythrocytes were irradiated with single doses, and identical doses split into two fractions with an interval time of 3.5 h between following exposures. The obtained results indicated that the irradiation of enucleated human erythrocytes with split doses caused a reduction of hemolysis (2.4 times), a decrease in the level of damage to membrane lipids and the contents of MetHb, compared with identical single doses. However, the splitting of radiation doses did not change the level of damage to the membrane proteins, as was estimated with a maleimide spin label. The obtained results suggest that a decrease in the level of damage to lipids was related to a decrease in hemolysis.

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In the present work we have studied some of the indicators of oxidative damage of the digestive gland tissue of two populations of mussels Mytilus galloprovincialis: native mussels cultured in an aquaculture farm and contaminated mussels collected from the polluted marine area of the French M editerranean coast located nearby Tamaris and La Seyne-sur-mer -small towns in close proximity to Toulon. * Corresponding author: kgwozdz@biol.uni.lodz.pl Copyright© by Institute of Oceanography, University of Gdańsk, Poland 34Activities of antioxidant enzymes catalase (CAT) and glutathione peroxidase (GPx) were analyzed, as well as the amounts of glutathione (GSH) and malonyldialdehyde (M DA). Glutathione is the most abundant low molecular cellular antioxidant, while malonyldialdehyde is the main product of lipid peroxidation. Additionally, the activity of lactate dehydrogenase-LDH, a marker of cell membrane damage, was determined. We have found an elevated activity of CAT and GPx in mussels from the contaminated areas -161.76 and 45.36 U mg -1 protein, respectively vs. 98.68 and 29.84 U mg -1 protein in the control mussels. The contaminated mussels also showed an elevated content of M DA -9.32 nmol mg -1 protein) vs. 7.57 nmol mg -1 protein in the control glands. The concentration of heavy metals (Fe, M n, Zn, Cu, Ni, Pb, Cd) in the digestive gland, except lead, was significantly higher in mussels from the polluted area. Contrarily, the level of GSH in contaminated mussels was about two-fold lower than that in the control mussels -2.85 µmol GSH mg -1 protein vs. 5.81 µmol GSH mg -1 protein. At the same time, no significant differences in LDH activity were observed between the two mussel populations.