Biologia

Lead (Pb), a widespread contaminant in terrestrial landscape, is highly detrimental to plant and animal life. Specifically, Pb-contaminated soils cause a sharp decrease in crop productivity, thereby posing a serious risk to agriculture. A study was planned to investigate the toxic effect of Pb2+ (0, 16, 40 and 80 mg L−1) in the seedlings of maize (Zea mays), in terms of induced physiological and biochemical changes at initial hours of treatment (0–8 h). Increased accumulation of malondialdehyde (MDA) served as an indicator of cellular peroxidation. At 80 mg L−1 Pb2+, MDA content enhanced over the control by 175% after 2 h of exposure and increased further to 461% greater over the control after 8 h of exposure. Elevated superoxide ion (O 2 −. ) and H2O2 contents suggested oxidative damage to the plants. The level of H2O2 increased over control by 70%, 80%, 135% and 182% at 2, 4, 6, and 8 h after exposure to 16 mg L−1 Pb2+, respectively. In situ histochemical localization confirmed the level of lipid peroxides, increased accumulation of OO 2 −. and loss of membrane integrity upon Pb2+ treatment. Pb2+-induced oxidative stress triggered significant changes in the activities of antioxidant enzymes. A concentration-dependent increase was observed in the activities of the superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and glutathione reductase (GR) in response to Pb2+, whereas catalases (CAT) was not able to provide protection against oxidative stress. These observations imply that Pb2+ -induced oxidative stress during initial period (0–8 h) of exposure involved ROS accumulation and upregulation of scavenging enzymes except CAT as a defense against Pb2+-toxicity.

Specific activity dynamics and isozyme composition of antioxidant enzymes ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD) were followed during the vegetation period in the young needles of Pinus mugo Turra, P. sylvestris L. and their putative hybrids. Tested enzymes differed in their dynamics showing the highest APX and CAT activities in the spring and autumn and the highest SOD activity in summer. The outlined course of enzyme activity was characteristic for all the three taxa compared. The level of specific enzyme activities was relatively constant in investigated taxa reaching statistical significance in some months of the scored period only. The same was true of the antioxidant enzyme activities of P. mugo individuals growing at different altitudes. Of the enzymes assayed, catalase was the most active. Hybrid individuals exhibited prevailingly intermediate level of their enzyme activity compared to the parental species. The dynamics of SOD correlated with intensity of UV irradiation during vegetation period. Partial correlation was observed between specific enzyme activities and isozyme composition.

Coxiella burnetii is a worldwide zoonotic pathogen causing Q fever in various animal species and humans. In Slovakia, cases of C. burnetii infection in both animals and humans are confirmed every year. The role of horses in the epidemiology of this neglected disease is still unclear. In our study, we focused on a serosurvey of C. burnetii in the equine population in Slovakia by the ELISA method. Subsequently, a nested PCR was performed to detect the 16S rRNA fragment of the genus Coxiella. Among 184 horse sera, the presence of specific antibodies to C. burnetii was detected in four samples, representing a 2.17% seropositivity. All the positive horses were mares; two originated from Central Slovakia and two from Eastern Slovakia. Although the number of positive samples was too small for a determination of statistical significance, our results provide the first confirmation of antibodies to C. burnetii in horses from Slovakia. Although no positive PCR result was obtained, these serological findings may help to clarify the circulation of the pathogen in the environment.

Xylanase Z (XynZ) is a prime part of cellulosome of Clostridium thermocellum. The several domains of the cellulosome complexes are frequently tethered to one another by intrinsically messy regions. This is multidomain xylanase comprising of N-terminus feruloyl esterase followed by substrate binding, dockerin and the catalytic domains. This study design was established to check the expression, activities and other characteristics of different variants of Xylanase Z produced by the C-terminal (XynZ-CB), N-terminal (XynZ-BC) and both terminals (XynZ-BCB) binding domain to catalytic domain in different arrangements. XynZ variants of C. thermocellum with binding domain committed with catalytic domain of C-terminal (XynZ-CB) and N-terminal (XynZ-BC) and both terminals (XynZ-BCB) binding domain and one with catalytic domain at both terminals of the binding domain (XynZ-CBC) were checked in E. coli in different levels like 15, 30, 30, and 33% of cell proteins, respectively. The specific xylanase Z activities of XynZ-CB, XynZ BC, XynZ-BCB and XynZ-BCB were 72, 68, 67 and 200 U mg−1, though their equimolar basis activities were 4176, 3944, 5092 and 19,200 U μM−1 compared to xylan (birchwood). The over-all activities of XynZ-CB, XynZ-BC, XynZ-BCB and XynZ-CBC produced in fermentation culture were 3678, 3579, 3800 and 5400 U L−1 OD600−1, respectively. The results showed that overall yield of XynZ-C remained manifold higher than all other variants due to combined effect of its specific activity and expression level while the activity of variant XynZ-CBC was increased four folds on equimolar basis as compared to its native form. The fruit saccharification increased with the treatment of xylanase and cellulase.

A hydrogenotrophic, mesophilic methanogen designated as strain T53BJ was isolated from anaerobic digester continuously fed with agro-industrial waste. Cells were stained Gram negative, spiral shaped, motile and found resistant to cell lysis by SDS and hypotonic solution. Growth occurred with optimum (i) temperature of 30 °C (20–40 °C) (ii) pH of 7.0 (6.5–8.5), in the presence of 0.0–0.2 M NaCl with a doubling time of 73.43 h and utilized only hydrogen and carbon dioxide (H2:CO2; 4:1) as a sole source of carbon and energy. The phenetic and phylogenetic analysis based on 16S rRNA and mcrA gene sequences revealed close affiliation of T53BJ strain to the genus Methanospirillum spp. This is the first report about isolation of hydrogenotrophic Methanospirillum spp. from anaerobic digester fed with fruit waste, press mud and neem seed cake, suggesting its potential use for bioaugmentation of anaerobic reactors or upgrading biogas/ syngas to methane.

As poikilohydric organisms, lichens are capable of storing significant amounts of atmospheric water. Epiphytes that intercept rainfall change the amount and chemical composition of throughfall water, affecting water balance and microclimate of forest ecosystems. The aim of the study was to investigate the differences in the process of changes/increase in the amount of water in three lichen species: Evernia prunastrii, Hypogymnia tubulosa and Platismatia glauca. In the experiment, conducted under laboratory conditions, samples of thalli were wetted with constant doses of water and weighed in order to determine the amount of water storage capacity from simulated rainfall. The studied lichen species differed in terms of process dynamics and values of water storage capacity, probably due to the morphological structure of thalli. Average water retention was the highest in Platismatia glauca (33.58 %), lower in Evernia prunastrii (19.77 %) and the lowest in Hypogymnia tubulosa (15.38 %). Analyzed taxa with larger water storage capacity are also known to be more sensitive to air pollution.

Lithuania is situated in the north-western corner of the large distributional range of the herb field mouse, Apodemus uralensis. Apodemus uralensis is distributed mainly in the north-western part of Lithuania, where the majority of specimens were captured in the ecotones of mixed forests and open habitats (natural meadows, cornfields and fallow fields) and in open habitats bordering forests or situated ciose to them. Apodemus uralensis is rare in Lithuania: the average relative abundance was only 2.2 ind. per 100 trap-days and it accounted for up to 8.5% of all small mammals trapped. Avoidance of forest habitats and preference of ecotonic habitats, as well as the comparatively low abundance, are the main peculiarities of A. uralensis in the north-western corner of the range.

Pinus mugo (dwarf mountain pine) is an important component of European mountain ecosystems. However, little is known about the present genetic structure and population differentiation of this species at the DNA level, possibly due to a lack of nuclear microsatellite markers (SSR) developed for Pinus mugo. Therefore in this study we transferred microsatellite markers originally developed for Pinus sylvestris and Pinus taeda to Pinus mugo. This cross-species amplification approach is much faster and less expensive than isolation and characterization of new microsatellite markers. The transfer rates from the source species to Pinus mugo were moderately low (26%). There were no differences in microsatellite repeat motifs between the source species and Pinus mugo. Nuclear microsatellite markers successfully transferred to Pinus mugo can be applied to various genetic studies on this species, due to the high level of their polymorphism and high value of polymorphic information content.