Band 69, Heft 11

Hepatitis B virus (HBV) is the most common cause of liver infection. This can be treated by targeting HBV DNA polymerase (HDP). Although many drugs are available for the treatment, lamivudine is widely used because of its good safety profiles. Lamivudine targets the reverse transcriptase activity of HDP and restricts the viral growth. However, the available literature evidence showed that the mutations in the catalytic site of tyrosine (Y203), methionine (M204), aspartic acid (D205) and aspartic acid (D206) will significantly reduce the efficacy of lamivudine and creates a resistance. In particular, M204V mutation affects the drug binding mechanism and cause resistance to lamivudine. Therefore, in the present study, we made an attempt to understand the mechanism of lamivudine resistance with the aid of computational techniques. The docking results suggest that lamivudine was found to adopt most promising conformations with native type HDP by identifying M204 as a prospective partner for making polar contacts as compared to the mutant type HDP. The molecular dynamic (MD) results showed that the average atom, especially atoms of the native-type HDP-lamivudine complex, movements were small, displayed fast convergence of energy and charges in geometry. This highlights the stable binding of the lamivudine with native-type HDP as compared to mutant type HDP. The normalized mean square displacement and root mean square fluctuation analysis certainly indicates conformational changes in the HDP structure due to M204V mutation. Furthermore, the hydrogen bond analysis from the MD study demonstrated that there is decreased number of intermolecular hydrogen bonds in mutant HDP-lamivudine complex than that in the native-type HDP-lamivudine complex.

Heavy metals are a significant source of pollution in soils that have been demonstrated to exert significant toxic effect on soil microbial assemblages. Here we investigate the occurrence and metabolic characteristics of actinobacteria, which form a predominated component of farmland bacterial community near the town of Sereď in southwest Slovakia, contaminated by close nickel ore facility. Actinobacteria occurred in this environment with high concentrations of nickel (2.109 mg/kg), slightly above the natural occurrence of cobalt (355 mg/kg) and zinc (177 mg/kg), even too low concentration of iron (35.75 mg/kg) for a normal soil and not a toxic amount of copper (32.2 mg/kg) and cadmium (<0.25 mg/kg). The phylogeny was reconstructed using partial sequences of 16S rDNA genes of both, actinobacterial isolates and clones. A total of 105 actinobacterial representatives were divided into 66 species belonging to one order, 7 genera and 5 uncategorized groups. The selected 14 morphologically distinct isolates were able to produce drop collapsing, haemolytic and lipase activities. Whereas only 4 isolates produced dark brown melanin pigment and only 5 of them produced decolourization of the azo dye, all isolates tested were capable of assimilating all 11 sugars tested. All these actinobacterial isolates were resistant to nickel, cobalt, zinc, cadmium, copper, but the level of resistance differed between the individual isolates, and the resistance profiles of antibiotics (gentamycin, ampicillin, ciprofloxacin, chloramphenicol, erythromycin, rifampicin, penicillin-G) varied among them to a certain extent. Our results suggested that actinobacteria in soil contaminated by nickel present a relatively divergent group inside of microbial assemblage.

Enzyme production by immobilized Phanerochaete chrysosporium was evaluated in airlift bioreactor and agitated cultures. Free mycelium and immobilized mycelium on alginate beads were tested in the decolourization of 50 and 500 mg/L of Remazol Brilliant Blue R. Dye concentration did not inhibit the fungi development in all tests. In addition, high decolourization percentage of dye was found with free mycelium (99%) in agitated flasks and with immobilized mycelium in airlift (98%). However, decolourization period by immobilized mycelium (120 h) was greater than that by the free mycelium (14 h). Important manganese peroxidase, lignine peroxidase and laccase activities were identified in decolourization process. Manganese peroxidase appeared to be promoted by high dye concentrations during the treatment with immobilized mycelium, but this enzyme was not detected with free mycelium in airlift. Bioreactor prompted also laccase and lignine peroxidase actions in both tests; free mycelium registered a maximum laccase action of 31.569 × 103 U/L in 70 h, whereas immobilized mycelium registered 1.680 × 103 U/L in 170 h, while lignine peroxidase secretion by free P. chrysosporium was higher (1.300 × 103 U/L) than immobilized mycelium (1.250 × 103 U/L). Maximum laccase activity coincided with the maximum percentage of decolourization, however, high peroxidase activity was identified from the start of dye treatment.

Mitogen-activated protein kinase (MAPK) cascades participate in various processes, including plant growth and development as well as biotic and abiotic stress responses. MAPK kinases (MKKs), which link MPKs and MPKK kinases, are involved in MAPK cascades by mediating various plant stress responses. However, only a few MKKs from Brassica campestris (rape) have been functionally characterized. This study delivers the results from isolation and characterization of a novel gene, MKK2, from rape. Bioinformatics analysis revealed that the cDNA length of MKK2 is 1,344 bp with an open reading frame of 1,068 bp, which encodes a polypeptide containing 355 amino acids. The obtained MKK2 exhibited a predicted molecular mass of 39.3 kDa and an isoelectric point of 6.8. Quantitative real-time polymerase chain reaction analysis revealed that MKK2 expression can be induced by cold and salt. Western blot analysis revealed that MKK2 protein expression can be induced by cold, salt, and UV-B radiation. The MKK2 protein was localized in the nucleus. These results suggest that MKK2 is important for the regulation of cold- and salt-stress responses in plants.

A famous plant polyketide synthase (PKS) is a chalcone synthase (CHS), which catalyzes the formation of naringenin chalcone, a limiting factor for flavonoid biosynthesis. Flavonoids such as naringenin and kaempferol-3-O-(2″,6″-di-O-p-trans-coumaroyl glucoside) have been identified from the flower extracts of Melastoma decemfidum RoxB. Therefore, a study was conducted to clone and characterize the pks gene from M. decemfidum. A newly isolated full-length cDNA containing the pks sequence (designated MdCHS; GenBank accession No. KF234569) was found to harbour a 1,355-bp open reading frame encoding 392 amino acids. The deduced MdCHS protein, which had a predicted molecular weight of approximately 42.6 kDa, exhibited 89% sequence identity to CHS from Anthurium andraeanum (GenBank accession No. AY232492) and 91% to those from Camellia sinensis (D26594) and Camellia chekiangoleosa (ADW11243). Southern blot analysis indicated that at least five pks genes are present in M. decemfidum. Additionally, transcription analysis revealed that pks gene expression was higher in roots than in other tissues (shoots, leaves, stems, flower buds and flowers). In conclusion, the characterization and cloning of the MdCHS gene further elucidates its role in flavonoid biosynthesis.

In the presented paper we deal with the impact of the mature spruce stand on the accumulation and melting of snow cover at Červenec research area located in the Western Tatras at an elevation of 1420 m a.s.l. The work analyses the data obtained from the monitoring of snow cover during the period 2009–2014 (6 seasons). Since the season 2012/2013 the measurements have been also performed in a dead part of the stand and in a meadow. The results proved significant impact of the spruce stand on hydro-physical characteristics of snow cover — snow water equivalent, snow density, as well as on their change due to the dieback of the stand. The data measured at individual locations (open space in the forest, open meadow area, living and dead forest) were tested with the paired t-test for the significance of average differences. Average snow water equivalent in the living forest, dead forest and meadow was 42%, 47% and 83% of the reference value measured at the open space in the forest, respectively. The process of snow accumulation and melting was fastest at the open space, followed by the dead forest. In the living forest, the processes were the slowest.

In Ethiopia the population is rapidly expanding. As a consequence the landscape is rapidly changing. Eucalyptus plantations are increasing and irrigation projects are implemented. The hydrological effects of the changing landscape on river (low) flows have not been well documented and therefore the amount of water available in the future might be over optimistic. The objective of this paper is to establish how low flows have been impacted by new developments in irrigation and by landscape change. For this paper, we choose the Gilgel Abay in the headwaters of the upper Blue Nile basin, since it has both good quality discharge data and it is located in the Tana Beles growth corridor. Numerical and statistical means were used to analyze the 25 years of available low flow data. We found a statistically significant decreasing trend (P < 0.00001) of low flow in the Gilgel Abay. From 1980’s to 1990’s the low flow decreased by 25% and from 1990’s to 2000’s the low flow was reduced by 46%. The deterministic analysis with the Parameter Efficient Distributed (PED) model supported the statistical findings and indicated that in the middle of the nineteen nineties, after irrigation projects and eucalyptus plantations increased greatly, the low flows decreased more rapidly.

A mathematical model was applied for the Bükk Mountains (Hungary) to evaluate the effects of climate change on soil water balance elements and soil water regime. Model runs using SWAP model were performed for combinations of four distinctive soil types and three land use systems of arable land, grassland, and forest. The temporal variation of soil water regime under changing climatic conditions was examined considering no land cover change occurring in the future. The climate data consisted of the predictions of two regional climate models, the Swiss CLM and the Swedish RCA. The RCA results showed 45% to 50% and the CLM showed 5% to 14% higher future precipitation outlook compared to present conditions. Considering different land use types, the projected number of days with soil moisture deficit was the highest in forest ecosystems for both the upper 50 cm soil layer and the whole soil profile, which could be as high as 61% of days below optimal soil water content range. Our results showed increased water fluxes, especially in deep percolation in far future period and a strong influence of soil properties on the changes in the climate model results, indicating significant long-term effects of climate change on soil water regime.

In a global meta study, which contained 157 biological soil crust (BSC) samples from all climatic regions worldwide, climatic and soil texture threshold values favoring BSC development were derived. Response variable was the “relative crust biomass”, which was computed per literature source as the ratio between each individual crust biomass value of the given study to the study maximum value reported. Four crust types were distinguished: cyanobacterial, lichen, green algal and moss crusts. To quantify threshold conditions at which crust biomass responded to differences in texture and climate, we (I) determined correlations between bioclimatic variables, (II) calculated generalized linear models to determine the effect of typical climatic variables with soil clay content and with study site as a random effect. (III) Thresholds of climatic and texture effects were identified using a regression tree. Three mean annual temperature classes for texture dependent BSC growth limitation were identified: (1) <9°C with a threshold value of 25% silt and clay (limited growth on coarser soils), (2) 9–19°C, where texture did have no influence on relative crust biomass, and (3) >19°C at soils with <4 or >17% silt and clay. Non of the precipitation related bioclimatic variables did influence the relative crust biomass significantly. Because biocrust development is limited under certain climatic and soil texture conditions, it is suggested to consider soil texture in biogeochemical modeling of cryptogamic ground covers.

Transport of radioactive iodide 131I− in a structured clay loam soil under maize in a final growing phase was monitored during five consecutive irrigation experiments under ponding. Each time, 27 mm of water were applied. The water of the second experiment was spiked with 200 MBq of 131I− tracer. Its activity was monitored as functions of depth and time with Geiger-Müller (G-M) detectors in 11 vertically installed access tubes. The aim of the study was to widen our current knowledge of water and solute transport in unsaturated soil under different agriculturally cultivated settings. It was supposed that the change in 131I− activity (or counting rate) is proportional to the change in soil water content. Rapid increase followed by a gradual decrease in 131I− activity occurred at all depths and was attributed to preferential flow. The iodide transport through structured soil profile was simulated by the HYDRUS 1D model. The model predicted relatively deep percolation of iodide within a short time, in a good agreement with the observed vertical iodide distribution in soil. We found that the top 30 cm of the soil profile is the most vulnerable layer in terms of water and solute movement, which is the same depth where the root structure of maize can extend.

In drylands, water erosion can be a process with important economic and ecological implications, and is very dependent on the soil surface cover. There is broad agreement that biocrusts protect the soil from erosion in a wide range of circumstances. However, there is little information available on the effect of rain and biocrust types on this protective capacity and there is particularly very little knowledge on the erosive effects of runoff on biocrusts, which are expected to be larger in larger drainage areas, on the resistance of biocrusts to the combined effect of raindrops plus runoff flow and on the solute mobilisation by runoff in biocrusts. To answer these questions, we performed 96 rainfall-simulation in situ factorial experiments, including two biocrust types (cyanobacteria and lichens), three rain types (42, 63 and 77 mm h−1, always 20 min rain), four plot lengths (1, 2, 3 and 4 m long) and four replicates. In each experiment, runoff volume was measured and a runoff sample was taken to determine (i) the amount of dry matter in runoff, (ii) the amount of organic matter among the dry matter, (iii) the electrical conductivity, pH and alkalinity in runoff water. The main findings were: biocrusts strongly protected soil against water erosion, even under the most erosive conditions, and the protection increased with the successional development. Biocrusts were very resistant to the impact of raindrops and also to runoff flow, although an emergent hypothesis arose: under the most erosive conditions, a threshold of erodibility could be reached at the cyanobacterial biocrust. The lichen crust also protected the soil against the removal of soil soluble substances. The development of a biocrust could change the chemical composition of the solutes in runoff.

The heterogeneity of water flow was evaluated in sandy loam soil covered by grass. The radioactive tracer infiltration experiment was performed at two parallel plots with different irrigation intensities. Effective cross section and degree of preferential flow parameters were used to evaluate flow regime during the experiment. For both plots, the heterogeneity of water flow increased with depth. The differences in irrigation intensity did not result in different values of the effective cross section and degree of preferential flow, indicating similar flow regime within the two experimental plots. The heterogeneity of water flow in shallower depths (0–50 cm) did not change with cumulative infiltration except for early times/small cumulative infiltrations, when the flow paths of preferential flow were formed. In deeper depths (60–70 cm) the flow paths of preferential flow were formed later, and therefore, the heterogeneity of water changed with cumulative infiltration.

The study deals with the snow cover characteristics (snow depth — SD and snow water equivalent — SWE) concerning the mid-latitude forested catchment. Namely, the influence of the forest canopy (Picea abies (L.) Karst. and Fagus sylvatica L.) and altitude (ranging from 835 m a.s.l. to 1118 m a.s.l.) was investigated. Forest cover was proved to have a significant influence on the snow cover accumulation, reducing SWE by 50 % on average, compared to open sites. The elevation gradient concerning SWE ranged from 30 to 40 mm and from 5 to 20 mm per 100 m in open and forested sites, respectively. Its magnitude was found to be temporarily variable and positively related to the total seasonal snowfall amount. The SWE/SD variability among measurement sites (with different altitude) was higher in open sites compared to forested ones. The catchment SWE/SD variability increases significantly in the snowmelt period (March–April) both in open and forested locations. The differences among snow interception losses, concerning various elevations and the forest canopy, were not statistically significant.

Oscillations of the air temperature and tensiometric pressure of the soil water were measured in the experimental slope Tomšovka (Czech Republic, Jizera Mts, 822 m a.s.l.). The brown forest soil (Dystric Cambisols) is covered with Calamagrostis villosa, Avenella flexuosa and Vaccinium myrtilus. Thermometers were placed at a height of 5 and 200 cm above the grassland. The tensiometer was installed in the root zone of grass at a depth of 15 cm. Oscillations in a cloudless day, August 24, 2001, (sunshine duration 12.1 hour/day, daily total of global radiation 22.4 MJ/m2/day, maximum intensity of global radiation 1008 W/m2, transpiration 13.7 MJ/m2/day) were analysed in detail. The oscillations with a period of about 30 to 60 minutes were recorded in the air temperature course taken from 11 am to 5 pm. At the height of 200 cm oscillations ranged from 24 to 28°C. Concurrently, in the depth of 15 cm, the oscillations of tensiometric pressure in the range of −6 to −11 kPa were recorded from 8 am to 4 pm. It was concluded that the oscillations in the air temperature resulted from autonomous and self-regulated oscillations in the intensity of transpiration. It is evident that the 2-m air temperature was significantly influenced by transpiration of plants around the large area. The fact that the air temperature oscillated sharply confirms that the rate of transpiration was synchronized in this area. Vegetative cover thus created a self-regulated superorganism that substantially affected the temperature of the near-ground atmosphere layer.

Catch crop cultivation coupled with subsequent flood activity is an environmental friendly method of removing nutrient salts from soil in greenhouse. However, in comparison with the usual fallow period in greenhouse horticulture in Japan, a longer time is required for cultivation and soil drying after flooding. To minimize such time while retaining catch crop performance, temporal flooding was conducted in an experimental catch crop field of corn before harvest (i.e., pre-harvest temporal flooding), when crops were growing well and most nutrient salts within the soil had been taken up by the roots. Results showed that pre-harvest temporal flooding enhanced crop growth and stomatal opening; hence, evapotranspiration (mostly transpiration) was increased to a high value (3.5 times that of bare soil plot in greenhouse). Therefore, compared with the bare soil field, there was a remarkable pronounced decrease in the soil water content due to evapotranspirational water loss in the catch crop field after temporal flooding. Furthermore, the total nutrient (nitrogen) uptake by crops was also significantly accelerated in relation to pre-harvest flooding owing to the increase in crop growth. It was also found that electrical conductivity and nitrate nitrogen concentration of soil solution (at a soil-water ratio of 1:5) decreased with time owing to root uptake, and were at a fairly low level when pre-harvest flooding was conducted. These results suggest that pre-harvest temporal flooding shortens the implementation time by accelerating soil drying, and increases salt removal by root uptake; thus, this method delivers considerable advantages for practical use in catch crop cultivation.

Lacewings are known as biological control agents, substantially reducing populations of aphids and spider-mites. The study focuses on gregarines parasitizing their brown lacewing hosts. The occurrence of the gregarine species Hyalospora hemerobii Geus, 1969 in brown lacewings (Hemerobiidae) in NE Slovenia was investigated. Seven brown lacewing species were surveyed and in five of them (Hemerobius humulinus, H. micans, H. marginatus, Micromus variegatus and Sympherobius pygmaeus) gregarines were present. Trophozoites, solitary gamonts, associations, syzygies and gametocysts were recognized. In this paper syzygy of H. hemerobii is illustrated for the first time. In some trophozoites the epimerite was present, associations were biassociative and caudofrontal. The occurrence of the parasite in Hemerobius micans was studied in 2011 and 2013. In 2011, gregarines occurred from June to September, and in 2013 from June to October. An infection rate within the range of 10–86.7% was detected. The average number of solitary gregarines per infested host increased progressively, from June to September/October. This is the first investigation of seasonal patterns in the occurrence of any known gregarine species parasitizing Neuropterida.

Two new species of oribatid mites, Suctobelbella (Ussuribata) phylliformis sp. n. (Suctobelbidae) and Neoribates (Neoribates) paratuberculatus sp. n. (Parakalummidae), are described from ferralitic soil of polydominant forest in Dong Nai Culture and Nature Reserve, southern Vietnam. Suctobelbella (Ussuribata) phylliformis sp. n. is similar morphologically to S. (U.) separata Mahunka, 2001, however, the new species differs from the latter by the number of genital and adanal setae, the morphology of the knob-like tubercle and the number of lateral prodorsal teeth. Neoribates (Neoribates) paratuberculatus sp. n. is similar morphologically to N. (N.) tuberculatus Willmann, 1956, however, the new species differs from the latter by the smaller body size, density of tubercles on pteromorphs and the morphology of bothridial setae. The validity of Suctobelbella (Ussuribata) is discussed; an identification key to all species of this subgenus is given.

A new species of Australobius Chamberlin, 1920 (Lithobiidae: Lithobiinae), from Jiuzhaigou of the Qinghai-Tibet Plateau is described as Australobius apicicornis sp. n. The new species is distinguished from two recorded congeneric species from the Qinghai-Tibet Plateau by having 24 antennal segments, eight ocelli, lacking porodonts, and with accessory claws in 14 legs. A key to the Chinese species of Australobius is presented.

Melia azedarach is a plant species whose fruits posses nematicidal and insecticidal activity. In this study, we tested two M. azedarach extracts: a crude methanolic fruit extract (CRU) and its limonoids fraction (LIM) produced after partitioning with dichloromethane to check their insecticidal activity against beet armyworm Spodoptera exigua. Both extracts disturbed development of S. exigua. After exposure to CRU and LIM, hatching success was slightly lower, larval-pupal and pupal-imago moulting was significantly disturbed. In physiological studies, CRU extracts decreased the heartbeat of S. exigua pupae. Electron microscopic studies revealed that both extracts caused malformations of fat body and midgut cells. The most common observed malformations were: vacuolization of mitochondria, swollen endoplasmic reticulum and degeneration of nuclei. Obtained results indicated that M. azedarach fruits are a source of substances that may be used in plant protection against S. exigua. Despite the fact that M. azedarach extracts do not cause acute effects, their usage may lead to serious disturbances within exposed insects and significantly decrease activity of pests.

The present study was carried out in three seasons — spring, summer and autumn in Topolnitsa Dam Lake (Bulgaria) which has been subjected to continuous contamination with trace metals due to copper extraction in the area. We investigated the trace metal levels in surface water and liver samples of European perch (Perca fluviatilis L.). We also linked the metal levels we determined with the various histological and biochemical changes which we observed. Lesions in the liver parenchyma were found to be degenerative and necrotic, as well as, they were presented as hyperemia which consequently leads to disturbances in the hepatic blood circulation. Activities of the hepatic enzymes lactate dehydrogenase (LDH), alanine aminotransferase (ALAT) and aspartate aminotransferase (ASAT) were found to be significantly elevated, particularly in summer. Therefore, based on our results we could recommend that the investigated tissue and cell alterations may be successfully applied as reliable biomarkers for monitoring polluted with a mixture of trace metals freshwater ecosystems.

The Chinese Bulbul (Pycnontus sinensis) has an extensive distribution throughout southern China. Investigators have reported that the species has expanded its distribution range northward since 1995. We performed a literature review and analysis to examine the relationships between the range expansion of the species and the changes of climate and habitat. We found that the northward range expansion was associated with the increased temperature and human created habitat. We believe that the combination of the increased temperature and the ability to utilize human created habitat while maintaining genetic diversity resulted in the population increase and range expansion of the species. We suggest that increased temperature and human disturbance could lead to evolutionary and distributional changes of some species such as the Chinese Bulbul, therefore possibly making these species indicators of climate change.

This study deals with an interesting record of exotic pest thrips Hercinothrips femoralis (Reuter, 1891) small population in the Carpathian mountain area (Vysoké Tatry Mts, N Slovakia) during the extensive research on high altitude forest succession. Hercinothrips femoralis is a well-known African pest species that has been introduced into the temperate regions of Europe, surviving only in glasshouses. The record in the coldest altitudes ever published (more than 1,000 m a.s.l.) indicates a role of passive migration and an effort of insects to taste ecological and environmental limits in their distribution.