Bongkrekic acid and atractyloside inhibits chloride channels from mitochondrial membranes of rat heart

The aim of this work was to characterize the effect of bongkrekic acid (BKA), atractyloside (ATR) and carboxyatractyloside (CAT) on single channel properties of chloride channels from mitochondria. Mitochondrial membranes isolated from a rat heart muscle were incorporated into a bilayer lipid membrane (BLM) and single chloride channel currents were measured in 250/50 mM KCl cis/trans solutions. BKA (1-100 microM), ATR and CAT (5-100 microM) inhibited the chloride channels in dose-dependent manner. The inhibitory effect of the BKA, ATR and CAT was pronounced from the trans side of a BLM and it increased with time and at negative voltages (trans-cis). These compounds did not influence the single channel amplitude, but decreased open dwell time of channels. The inhibitory effect of BKA, ATR and CAT on the mitochondrial chloride channel may help to explain some of their cellular and/or subcellular effects.     

Use of dissolved ozone for controlling planktonic and sessile bacteria in industrial cooling systems

Cooling water treatment requires effective, environmentally-safe biocides compatible with system operation. The unique combination of high biocidal activity during use with no toxic discharge, could render dissolved ozone a safe biocide for cooling water treatment. Planktonic and sessile cells of Pseudomonas fluorescens (a frequent microbial contaminant of industrial systems) were used in this work to assess the biocidal effectiveness of ozone. Dissolved ozone showed to be effective at concentrations between 0.1 and 0.3 ppm, to eliminate completely the levels of planktonic cells used in this paper (10⁷–10⁸ cell/ml) within a range of contact times between 10 and 30 min. However, ozone at 0.15 ppm was only able to diminish sessile cell population by two or three orders of magnitude. This minor biocidal effectiveness of ozone against bacterial biofilms is discussed in this paper, taking into account recent concepts on structure and dynamics of biofilms. Different metallic substrata were assayed to verify if there was any effect of metal nature on the biocidal action. Open circuit potentials vs. time experiments and potentiodynamic polarization curves were made for assessing the effect of dissolved ozone on the corrosion behavior of the metals tested.     

Bradykinin Postconditioning Protects Pyramidal CA1 Neurons Against Delayed Neuronal Death in Rat Hippocampus

Aims The present study was undertaken to evaluate possible neuroprotective effect of bradykinin against delayed neuronal death in hippocampal CA1 neurons if applied two days after transient forebrain ischemia in the rat. Methods Transient forebrain ischemia was induced in male Wistar rats by four-vessel occlusion for 8 min. To assess efficacy of bradykinin as a new stressor for delayed postconditioning we used two experimental groups of animals: ischemia 8 min and 3 days of survival, and ischemia 8 min and 3 days of survival with i.p. injection of bradykinin (150 μg/kg) applied 48 h after ischemia. Results We found extensive neuronal degeneration in the CA1 region at day 3 after ischemia/reperfusion. The postischemic neurodegeneration was preceded by increased activity of mitochondrial enzyme MnSOD in cytoplasm, indicating release of MnSOD from mitochondria in the process of delayed neuronal death. Increased cytosolic cytochrome c and subsequently caspase-3 activation are additional signs of neuronal death via the mitochondrial pathway. Bradykinin administration significantly attenuated ischemia-induced neuronal death, and also suppressed the release of MnSOD, and cytochrome c, and prevented caspase-3 activation. Conclusions Bradykinin can be used as an effective stressor able to prevent mitochondrial failure leading to apoptosis-like delayed neuronal death in postischemic rat hippocampus.     

Aminoguanidine Administration Ameliorates Hippocampal Damage After Middle Cerebral Artery Occlusion in Rat

The effects of a selective inducible nitric oxide synthase inhibitor aminoguanidine (AG) on neuronal cells survival in hippocampal CA1 region after middle cerebral artery occlusion (MCAO) were examined. Transient focal cerebral ischemia was induced in rats by 60 or 90 min of MCAO, followed by 7 days of reperfusion. AG treatment (150 mg/kg i.p.) significantly reduced total infarct volumes: by 70% after 90 min MCAO and by 95% after 60 min MCAO, compared with saline-treated ischemic group. The number of degenerating neurons in hippocampal CA1 region was also markedly lower in aminoguanidine-treated ischemic groups compared to ischemic groups without AG-treatment. The number of iNOS-positive cells significantly increased in the hippocampal CA1 region of ischemic animals, whereas it was reduced in AG-treated rats. Our findings demonstrate that aminoguanidine decreases ischemic brain damage and improves neurological recovery after transient focal ischemia induced by MCAO.     

Management of reedbeds: mosaic reed cutting does not affect prey abundance and nest predation rate of reed passerine birds

Reed passerine birds are strict habitat specialists inhabiting reedbed habitats. In Europe, many of these species are threatened due to loss and degradation of natural reedbeds. Another important factor that can negatively affect the abundance of reed passerines is commercial reed harvesting. Previous studies have shown negative impacts of large-scale winter reed cutting on passerine breeding assemblages and arthropod communities. The effect of reed cutting on a small scale, however, has not been studied experimentally to date. The aim of this study was to investigate whether and how small-scale, mosaic reed cutting influences prey abundance and nest predation rate of reed passerines. In June, after the reed had reached maturity, we conducted nest predation experiments with artificial nests and arthropod sampling using pan traps in cut reed patches, adjacent uncut reed patches and unmanaged reedbed. We found no differences in the risk of egg predation between three types of reedbeds. In contrast, the abundance of arthropods in cut and adjacent uncut reed patches was significantly higher than that in unmanaged reedbed. We assume this was caused by habitat heterogeneity, small size of cut patches and their rapid recolonization by arthropods from adjacent uncut patches. Our results suggest that in contrast to large-scale reed cutting, small-scale, mosaic reed cutting has no negative effect on nest survival and food abundance of reed passerine birds. However, given that we performed all experiments in June, i.e., when the reed was mature, our findings cannot be generalized to whole breeding period of all reed passerine birds. Therefore, temporal variation in nest predation rate and arthropod abundance in managed and unmanaged reedbeds during the entire breeding season should be examined in future studies.     

The Rep20 Replication Initiator From the pAG20 Plasmid of Acetobacter aceti

In the previously isolated pAG20 plasmid from the Acetobacter aceti CCM3610 strain, the Rep20 protein was characterized as a main replication initiator. The pAG20 plasmid origin was localized in the vicinity of the rep20 gene and contained two 21-nucleotide-long iteron sequences, two 13-nucleotide-long direct repeats, and a DnaA-binding site. Electrophoretic mobility shift assay and nonradioactive fragment analysis confirmed that the Rep20 protein interacted with two direct repeats (5′-TCCAAATTTGGAT′-3′) and their requirement during plasmid replication was verified by mutagenesis. Although the association could not be validated of the DnaA protein of from the host cells of Escherichia coli with the plasmid-encoded replication initiator that usually occurs during replication initiation, Rep20 was able to form dimeric structures by which it could bind the sequence of the rep20 gene and autoregulate its own expression. Targeted mutagenesis of the Rep20 protein revealed the importance of the third α-helix and ⁶³Lys, specifically during DNA binding. The second, closely adjacent β-sheet also took part in this process in which ⁵²Asn played a significant role.     

Role of histamine receptors in the effects of histamine on the production of reactive oxygen species by whole blood phagocytes

Aims

The diverse physiological functions of histamine are mediated through distinct histamine receptors. In this study we investigated the role of H₂R and H₄R in the effects of histamine on the production of reactive oxygen species by phagocytes in whole blood.

Main methods

Changes in reactive oxygen species (ROS) production by whole blood phagocytes after treatment with histamine, H₄R agonists (4-methylhistamine, VUF8430), H₂R agonist (dimaprit) and their combinations with H₄R antagonist (JNJ10191584) and H₂R antagonist (ranitidine) were determined using the chemiluminescence (CL) assay. To exclude the direct scavenging effects of the studied compounds on the CL response, the antioxidant properties of all compounds were measured using several methods (TRAP, ORAC, and luminol–HRP–H₂O₂ based CL).

Key findings

Histamine, 4-methylhistamine, VUF8430 and dimaprit inhibited the spontaneous and OZP-activated whole blood CL in a dose-dependent manner. On the other hand, only VUF8430 was able to inhibit PMA-activated whole blood CL. Ranitidine, but not JNJ10191584, completely reduced the effects of histamine, 4-methylhistamine and dimaprit. The direct scavenging ability of tested compounds was negligible.

Significance

Our results demonstrate that the inhibitory effects of histamine on ROS production in whole blood phagocytes were caused by H₂R. Our results also suggest that H₄R agonists in concentrations higher than 10^− 6 M may also influence ROS production via binding to H₂R.     

Starch degradation by glucoamylase Glm from Saccharomycopsis fibuligera IFO 0111 in the presence and absence of a commercial pullulanase

This study describes the course of enzymatic hydrolysis of the native corn starches Maritena 100 and Maritena 300. Hydrolyses were carried out with glucoamylase Glm produced by Saccharomycopsis fibuligera IFO 0111, which degrades also native starch, with the purpose to substitute a two-step hydrolysis (amylase followed by glucoamylase) by a one-step process (glucoamylase only). Hydrolysis generally became more effective by adding the pullulanase Promozyme D, which cleaves alpha-1,6-glycosidic bonds more effectively than glucoamylase Glm does. The time course (kinetics) of hydrolysis was followed by determination of the glucose concentration and calculation of dextrose equivalents.     

Morava River alluvial meadows on the Slovak–Austrian border (Slovak part): plant community dynamics, floristic and butterfly diversity – threats and management

The Morava river forms a border 71 km in length between Slovakia and Austria. Along this stretch of river is the largest complex of flooded grasslands in Central Europe, most of which lays on the Slovak side. Most of the grasslands belong to the subcontinental vegetation alliance Cnidion, with smaller areas of Alopecurion and Molinion. The grasslands are biotopes of many endangered plant and animal species. The influence of water regime dynamics on species composition have been studied since 1992 along permanent transects. The results of studies on the relation between water regime dynamics, vegetation and soils on the whole section of the Morava River floodplain are presented.     

Relationship between incomplete synapsis and chiasma localization

One of the subjects within the meiotic field that has been actively investigated in the recent years is the temporal and functional relationships between meiotic recombination, cohesin loading and synaptonemal complex (SC) assembly. Although the study of meiotic mutants has shed some light, many questions remain to be answered. Here, we have studied this topic in the orthopteran Paratettix meridionalis, a species with telocentric chromosomes, which shows two unusual cytological features: pairing and synapsis of homologues during prophase I are restricted to the non-centromeric distal regions and extremely distal chiasma localization in metaphase I bivalents. In order to determine whether there is a relationship between both phenomena, we have used: (1) a spreading technique for following the ultrastructure of SC assembly and (2) immunofluorescence for SMC3 and SMC1α cohesin subunits, which mark the development of the axial element (a SC component); the histone γ-H2AX, which mostly labels the sites of double-strand breaks; and the recombinase RAD51. Spermatocytes showed conspicuous polarization of both the maturation of cohesin axes and the initiation of meiotic recombination events. Consequently, it is proposed that maturation of cohesin axes, which begins in very distal regions, could drive the latter loading of recombinases to such regions. This restricted distribution of recombination events along homologues would finally be responsible for the incomplete pairing and synapsis observed in all autosomes of the complement and hence for chiasma localization. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. All authors contributed equally to this work.