Background and purpose:The effects of hydrogen peroxide (H2O2) on uterine smooth muscle are not well studied. We have investigated the effect and the mechanism of action of exogenous hydrogen peroxide on rat uteri contractile activity [spontaneous and calcium ion (Ca 2+ )-induced] and the effect of such treatment on anti-oxidative enzyme activities. Experimental approach: Uteri were isolated from virgin Wistar rats and suspended in an organ bath. Uteri were allowed to contract spontaneously or in the presence of Ca 2+ (6 mM) and treated with H2O2 (2 mM-3 mM) over 2 h. Anti-oxidative enzyme activities (manganese superoxide dismutase-MnSOD, copper-zinc superoxide dismutase-CuZnSOD, catalase-CAT, glutathione peroxidase-GSHPx and glutathione reductase-GR) in H2O2-treated uteri were compared with those in uteri immediately frozen after isolation or undergoing spontaneous or Ca 2+ -induced contractions, without treatment with H2O2. The effect of inhibitors (propranolol, methylene blue, L-NAME, tetraethylamonium, glibenclamide and 4-aminopyridine) on H2O2-mediated relaxation was explored. Key results: H2O2 caused concentration-dependent relaxation of both spontaneous and Ca 2+ -induced uterine contractions. After H2O2 treatment, GSHPx and MnSOD activities were increased, while CuZnSOD and GR (In Ca 2+ -induced rat uteri) were decreased. N w -nitro-L-arginine methyl ester antagonized the effect of H2O2 on Ca 2+ -induced contractions. H2O2-induced relaxation was not affected by propranolol, potentiated by methylene blue and antagonized by tetraethylamonium, 4-aminopyridine and glibenclamide, with the last compound being the least effective. Conclusions and implications: H2O2 induced dose-dependent relaxation of isolated rat uteri mainly via changes in voltagedependent potassium channels. Decreasing generation of reactive oxygen species by stimulation of anti-oxidative pathways may lead to new approaches to the management of dysfunctional uteri.

Unique marshland area in the Danube floodplain -Special Nature Reserve Gornje Podunavlje is considered to be one of the last aquatic flora and fauna refuges in the region. The revitalization projects in SNP Gornje Podunavlje started in 2011. They were conducted in order to protect biodiversity and to provide the natural ecosystem. The aim of this study was to investigate and compare the present diversity and distribution of the charophytes in five ponds of SNR Gornje Podunavlje, depending on phases of the revitalization process within the ponds. The researched area includes the following ponds: Semenjača, Šarkanj, Široki rit, Sakajtaš and Ribolov. The Široki rit pond was under the process of revitalization during the field surveys, Semenjača and Šarkanj have already been revitalized, and Ribolov and Sakajtaš were not exposed to the revitalization processes at all. The field surveys were conducted monthly, from May to September 2016. Water quality parameters were measured in situ and in laboratory. Ponds differed considerably when it comes to water chemistry; Semenjača and Šarkanj were associated with highest nutrient concentrations, while Široki rit was characterized by highest conductivity and water hardness. The highest diversity was found in Široki rit pond, which was still in process of revitalization when the field survey was conducted. Charophytes were not detected within previously revitalized ponds (Semenjača and Šarkanj). Eight species of charophytes were detected:

The importance of biofilms in caves, the diversity of microorganisms in them, their mutual relationship and relationship with the substratum are among the advancing research topics in microbial biospeleology. This research is making contribution to the knowledge about biofilms at cave entrances and phototrophic communities in them. In that manner, biofilms from the entrance zone of the Petnica Cave were examined. Light microscopy showed that cyanobacteria were exclusively dominant phototrophs (34 taxa out of 39 total taxa recorded) with coccoid forms prevailing (28 taxa); simple trichal forms were present to a lesser extent, while heterocytous ones were completely absent. Genera Gloeocapsa, Chroococcus,Gloeothece and Leptolyngbya were the most diverse. Four green algal genera characteristic for aerophytic habitats (Apatococcus, Desmococcus, Haematococcus and Trentepohlia) were also recorded, while Bacillariophytawere observed sporadically. Three groups of sampling sites were distinguished based on recorded taxa, their richness and similarity, using non-metric multidimensional scaling (NMDS). Quantitative biofilm characteristics were also assessed - the content of chlorophyll a (Chl a) was determined, as well as the contents of water, organic and inorganic matter. Chl a had a significant positive correlation with the content of organic matter (r=0.904, P=0.013).

The role of oxidative stress in cisplatin (CP) toxicity and its prevention by pretreatment with selenium (Se) was investigated. Male Wistar albino rats were injected with a single dose of cisplatin (7.5 mg CP/kg b.m., i.p.) and selenium (6 mg Se/kg b.m, as Na2SeO3, i.p.) alone or in combination. The results suggest that CP intoxication induces oxidative stress and alters the glutathione redox status: reduced glutathione (GSH), oxidized glutathione (GSSG) and the GSH/GSSG ratio (GSH RI), resulting in increased lipid peroxidation (LPO) in rat liver. The pretreatment with selenium prior to CP treatment showed a protective effect against the toxic influence of CP on peroxidation of the membrane lipids and an altering of the glutathione redox status in the liver of rats. From our results we conclude that selenium functions as a potent antioxidant and suggest that it can control CP-induced hepatotoxicity in rats

No abstract