Katalin Takács

Characteristics of α‐glycerophosphate‐evoked H2O2 generation in brain mitochondria

Characteristics of reactive oxygen species (ROS) production in isolated guinea‐pig brain mitochondria respiring on α‐glycerophosphate (α‐GP) were investigated and compared with those supported by succinate. Mitochondria established a membrane potential (ΔΨm) and released H2O2 in parallel with an increase in NAD(P)H fluorescence in the presence of α‐GP (5–40 mm). H2O2 formation and the increase in NAD(P)H level were inhibited by rotenone, ADP or FCCP, respectively, being consistent with a reverse electron transfer (RET). The residual H2O2 formation in the presence of FCCP was stimulated by myxothiazol in mitochondria supported by α‐GP, but not by succinate. ROS under these conditions are most likely to be derived from α‐GP‐dehydrogenase. In addition, huge ROS formation could be provoked by antimycin in α‐GP‐supported mitochondria, which was prevented by myxothiazol, pointing to the generation of ROS at the quinol‐oxidizing center (Qo) site of complex III. FCCP further stimulated the production of ROS to the highest rate that we observed in this study. We suggest that the metabolism of α‐GP leads to ROS generation primarily by complex I in RET, and in addition a significant ROS formation could be ascribed to α‐GP‐dehydrogenase in mammalian brain mitochondria. ROS generation by α‐GP at complex III is evident only when this complex is inhibited by antimycin.

Stimulation of H2O2 generation by calcium in brain mitochondria respiring on α-glycerophosphate

It has been reported recently (Tretter et al., 2007 b) that in isolated guinea pig brain mitochondria supported by α‐glycerophosphate (α‐GP) reactive oxygen species (ROS) are produced through the reverse electron transport (RET) in the respiratory chain and by α‐glycerophosphate dehydrogenase (α‐GPDH). We studied the effect of calcium on the generation of H2O2 as measured by the Amplex Red fluorescent assay in this model. H2O2 production in α‐GP‐supported mitochondria was increased significantly in the presence of 100, 250, and 500 nM Ca2+, respectively. In addition, Ca2+ enhanced the membrane potential, the rate of oxygen consumption, and the NAD(P)H autofluorescence in these mitochondria. Direct measurement of α‐GPDH activity showed that Ca2+ stimulated the enzyme by decreasing the Km for α‐GP. In those mitochondria where RET was eliminated by the Complex I inhibitor rotenone (2 μM) or due to depolarization by ADP (1 mM), the rate of H2O2 formation was smaller and the stimulation of H2O2 generation by Ca2+ was prevented partly, but the stimulatory effect of Ca2+ was still significant. These data indicate that in α‐GP‐supported mitochondria activation of α‐GPDH by Ca2+ leads to an accelerated RET‐mediated ROS generation as well as to a stimulated ROS production by α‐GPDH.

Mapping of topsoil texture in Hungary using classification trees

ABSTRACT Spatial information about physical soil properties is in great demand, being basic input data in numerous applications. Soil texture can be characterized by different approaches, such as particle size distribution, plasticity index or soil texture classification. In accordance with the increasing demands for spatial soil texture information, our aim was to compile a topsoil texture class map for Hungary with an appropriate spatial resolution, using the United States Department of Agriculture soil texture classes. The ‘Classification and Regression Trees’ method was applied because it is widely used in Digital Soil Mapping, and has numerous advantages. Primary soil data were provided by the Hungarian Soil Information and Monitoring System. A digital elevation model and its derived components, geological and land cover map, and appropriate remotely sensed products together with the soil map featuring overall physical properties provided by the Digital Kreybig Soil Information System were used as auxiliary environmental co-variables. The resulting map can be used as direct input data in meteorological and hydrological modelling as well as in spatial planning.

Variations for the Implementation of SCORPAN’s “S”

Development of DSM can be notably attributed to frequent limitations in the availability of proper soil information; consequently, it has been typically used in cases featured by limited soil data. Since SCORPAN equation includes other or previously measured properties of soil, the usage of legacy soil data supports the applicability of DSM and improves the accuracy of DSM products as well. Nevertheless, the occurrent abundance of available soil information poses new demands on and at the same time opens new possibilities in the application of DSM methods. A great amount of soil information has been collected in Hungary in the frame of subsequent surveys and assessments. The majority of these legacy soil data were integrated in various spatial soil information systems. Our paper presents three approaches for the application of Hungary’s most extended legacy soil data source in goal-oriented digital soil mapping.

Compilation of Functional Soil Maps for the Support of Spatial Planning and Land Management in Hungary

The tasks of national spatial planning (i.e., delineation of areas with natural constraints or areas with excellent productivity; support of irrigation strategies; flood, drought, and climate change impact risk assessment) increasingly demand advanced or new kinds of spatial soil information, which cannot be fully satisfied by legacy soil maps or formerly elaborated databases. Due to the lack of recent, extended, nationwide mapping, the data of previous surveys should be exploited thoroughly. Digital soil mapping integrates geographic information systems (GIS), geostatistical, and data mining tools and makes possible the elaboration of target-specific soil maps with improved and/or specific thematic, spatial, and temporal accuracy as opposed to former, more general soil maps. For the satisfaction of the recent demands, soil conditions of Hungary have been digitally mapped based on various available recent and legacy soil datasets, and spatially exhaustive, environmental, and auxiliary information. The produced digital soil property maps have been miscellaneously utilized in various regional planning activities.

Soil erosion of Hungary assessed by spatially explicit modelling

ABSTRACT The conservation of soil resources is increasingly becoming a critical issue worldwide, with growing interest in carbon stocks and water storage within the soil. Hungary is no exception, and there has been a demand for a country level soil erosion map that incorporates digital information available from the latest surveys and digital mapping campaigns. The map presented in this paper in based on the extremely wet year of 2010, and thus provides users a 1:100,000 scale ‘worst case scenario’ of soil erosion risk in Hungary (see Main Map). Results from both the Universal Soil Loss Equation and the Pan-European Soil Erosion Risk Assessment models were combined in order to achieve a map that can be used by a wide range of professionals. Both models estimate soil erosion by water in tonnes per hectare per year.

Spatial risk assessment of hydrological extremities: Inland excess water hazard, Szabolcs-Szatmár-Bereg County, Hungary

Inland excess water hazard was regionalized and digitally mapped using auxiliary spatial environmental information for a county in Eastern Hungary. Quantified parameters representing the effect of soil, geology, groundwater, land use and hydrometeorology on the formulation of inland excess water were defined and spatially explicitly derived. The complex role of relief was characterized using multiple derivatives computed from a DEM. Legacy maps displaying inland excess water events were used as a reference dataset. Regression kriging was applied for spatial inference with the correlation between environmental factors and inundation determined using multiple linear regressions. A stochastic factor derived through kriging the residual was added to the regression results, thus producing the final inundation hazard map. This may be of use for numerous land-related activities.

Spatial distribution of selected soil features in Hajdú-Bihar county represented by digital soil maps

With the ongoing DOSoReMI.hu project we aimed to significantly extend the potential, how soil information requirements could be satisfied in Hungary. We started to compile digital soil maps, which fulfil optimally general as well as specific national and international demands from the aspect of thematic, spatial and temporal accuracy. In addition to relevant and available auxiliary, spatial data themes related to soil forming factors and/or to indicative environmental elements we heavily lean on the various national soil databases. The set of the applied digital soil mapping techniques is gradually broadened. In our paper we present some results in the form of brand new soil maps focusing on the territory of Hajdú-Bihar county.

Long-term ice phenology records from East Central Europe

A dataset of annual freshwater ice phenology was compiled for the largest river (Danube) and the largest lake (Lake Balaton) in eastern–central Europe, extending regular river and lake ice monitoring data through the use of historical observations and documentary records dating back to AD 1774 and AD 1885, respectively. What becomes clear is that the dates of the first appearance of ice and freeze-up have shifted, arriving 12–30 and 4–13 days later, respectively, per 100 years. Break-up and ice-off have shifted to earlier dates by 7–13 and 9–27 days/100 years, except on Lake Balaton, where the date of break-up has not changed significantly. The datasets represent a resource for (paleo)climatological research thanks to the strong, physically determined link between water and air temperature and the occurrence of freshwater ice phenomena. The derived centennial records of freshwater cryophenology for the Danube and Balaton are readily available for detailed analysis of the temporal trends, large-scale spatial comparison, or other climatological purposes. The derived dataset is publicly available via PANGAEA at https://doi.org/10.1594/PANGAEA.881056.

S1.21 Thermodynamic constraints in the reversal of adenine nucleotide translocase during the reversal of F0–F1 ATP synthase caused by respiratory chain inhibition: Critical role of substrate-level phosphorylation

F1ATPase were studied by FT-ESEEM spectroscopy, using Mn(II) as a paramagnetic probe, which replaces the naturally occurring Mg(II) and maintains the enzyme catalytic activity. Purified F1ATPase still containing three endogenous tightly bound nucleotides, named MF1 (1,2), was obtained under mild conditions, whereas a harsher treatment gave a fully nucleotide depleted enzyme, named MF1 (0,0). When MF1(1,2) was loaded with Mn(II) in 1:0.8 ratio, the spectrum showed evidence of a nitrogen interacting with the metal, while this interaction was not present in the spectrum of MF1(0,0) loaded with Mn(II) in the same ratio. However, when MF1(0,0) was loaded with 2.4 Mn(II), the spectrum showed metal-nitrogen interaction resembling that of MF1(1,2) loaded with Mn(II) in 1:0.8 ratio. When MF1(1,2) was loaded with 2.4 Mn(II) the metalnitrogen interaction signal remained and a phosphorous coordination to the metal was also evident, indicating a binding of Mn to a site containing a tightly bound nucleotide but metal free. These results strongly support the role of the metal alone in structuring the catalytic sites of the enzyme while ESEEM technique appears to be a sensitive and suitable spectroscopic method for conformational studies of MF1 with the advantage of using proteins in frozen solution.