How the social parasitic bumblebee <Emphasis Type="Italic">Bombus bohemicus</Emphasis> sneaks into power of reproduction

Social parasitism is widespread in many groups of social living hymenopteran species and has also evolved in the genus Bombus. Cuckoo bumblebees (subgenus Psithyrus) are obligate brood parasites in nests of other bumblebee species. After nest usurpation and the killing of the host queen, the parasite female has to control worker reproduction in order to accomplish and maintain reproductive dominance and to ensure her reproductive success. The aim of our study was to examine whether the generalist parasitic bumblebee Bombus bohemicus monopolizes and prevents worker reproduction by physical or chemical means and to identify possible odor compounds involved therein. We performed bioassays with callow workers of the host Bombus terrestris and have shown that B. bohemicus females are able to suppress host worker ovarian development, when these host workers are under the direct influence of the parasite female. Furthermore, by chemical analyses, we have demonstrated that the parasite females adjust to the odor profiles of their host queens in order to maintain the level of fertility signaling inside the host colony although the host queen is absent. We also found that host workers change their odor profile after nest usurpation by the parasite female and consequently, we suggest that the host and parasite are caught up in a chemical arms race.     

Drivers of inter-year variability of plant production and decomposers across contrasting island ecosystems

Despite the likely importance of inter-year dynamics of plant production and consumer biota for driving community- and ecosystem-level processes, very few studies have explored how and why these dynamics vary across contrasting ecosystems. We utilized a well-characterized system of 30 lake islands in the boreal forest zone of northern Sweden across which soil fertility and productivity vary considerably, with larger islands being more fertile and productive than smaller ones. In this system we assessed the inter-year dynamics of several measures of plant production and the soil microbial community (primary consumers in the decomposer food web) for each of nine years, and soil microfaunal groups (secondary and tertiary consumers) for each of six of those years. We found that, for measures of plant production and each of the three consumer trophic levels, inter-year dynamics were strongly affected by island size. Further, many variables were strongly affected by island size (and thus bottom-up regulation by soil fertility and resources) in some years, but not in other years, most likely due to inter-year variation in climatic conditions. For each of the plant and microbial variables for which we had nine years of data, we also determined the inter-year coefficient of variation (CV), an inverse measure of stability. We found that CVs of some measures of plant productivity were greater on large islands, whereas those of other measures were greater on smaller islands; CVs of microbial variables were unresponsive to island size. We also found that the effects of island size on the temporal dynamics of some variables were related to inter-year variability of macroclimatic variables. As such, our results show that the inter-year dynamics of both plant productivity and decomposer biota across each of three trophic levels, as well as the inter-year stability of plant productivity, differ greatly across contrasting ecosystems, with potentially important but largely overlooked implications for community and ecosystem processes.     

Hydrogeochemical and biomedical insights into germanium potential of curative waters: a case study of health resorts in the Sudetes Mountains (Poland)

Germanium is considered to be a non-essential element; however, little is still known about its significance for living organisms. It exerts prophylactic and therapeutic effects in the treatment of serious diseases such as cancer, HIV infection, and others. Germanium does not exhibit acute toxicity, but, as it tends to accumulate in various organs and tissues, undesirable and even dangerous side effects have been reported after prolonged and/or high dosage application. In general, inorganic compounds of germanium are more toxic than its organic compounds. Further studies should be performed to elucidate the exact molecular mechanism of germanium action, to determine the safe and effective dose of germanium via curative/mineral waters, and to understand the applications and benefits of using germanium-enriched waters in balneotherapy. The geochemistry of curative (cold CO₂-rich, thermal) waters from spas in the Sudetes (Poland) was clarified in terms of components and mineral phases which might govern germanium. Germanium and silicon in thermal (above 20 °C) waters presumably result from the solubility of silicates in crystalline (granites, gneisses) aquifer rocks and might be controlled by neo-formed quartz. The cold CO₂-rich waters revealed a significant diversity of aqueous chemistry and relationships of germanium with iron, silicon, or arsenic. Locally, both in sedimentary (sandstones) and metamorphic (gneisses) aquifer rocks, primary (silicates) and/or secondary (oxides) iron-containing minerals likely release germanium into solution. In the CO₂-rich waters of the western part of the K?odzko Region, germanium distinctly correlates with arsenic. It is hypothesized that both elements are co-sourced from crystalline basement and/or migration of substances of post-magmatic origin along deep-seated dislocations related to the seismically active Po?í?í-Hronov fault zone. This area was proposed as the most prospective one for finding waters rich in germanium in the Sudetes.     

Detecting the effects of coal mining,acid rain,and natural gas extraction in Appalachian basin streams in Pennsylvania (USA) through analysis of barium and sulfate concentrations

To understand how extraction of different energy sources impacts water resources requires assessment of how water chemistry has changed in comparison with the background values of pristine streams. With such understanding, we can develop better water quality standards and ecological interpretations. However, determination of pristine background chemistry is difficult in areas with heavy human impact. To learn to do this, we compiled a master dataset of sulfate and barium concentrations ([SO₄], [Ba]) in Pennsylvania (PA, USA) streams from publically available sources. These elements were chosen because they can represent contamination related to oil/gas and coal, respectively. We applied changepoint analysis (i.e., likelihood ratio test) to identify pristine streams, which we defined as streams with a low variability in concentrations as measured over years. From these pristine streams, we estimated the baseline concentrations for major bedrock types in PA. Overall, we found that 48,471 data values are available for [SO₄] from 1904 to 2014 and 3243 data for [Ba] from 1963 to 2014. Statewide [SO₄] baseline was estimated to be 15.8 ± 9.6 mg/L, but values range from 12.4 to 26.7 mg/L for different bedrock types. The statewide [Ba] baseline is 27.7 ± 10.6 µg/L and values range from 25.8 to 38.7 µg/L. Results show that most increases in [SO₄] from the baseline occurred in areas with intensive coal mining activities, confirming previous studies. Sulfate inputs from acid rain were also documented. Slight increases in [Ba] since 2007 and higher [Ba] in areas with higher densities of gas wells when compared to other areas could document impacts from shale gas development, the prevalence of basin brines, or decreases in acid rain and its coupled effects on [Ba] related to barite solubility. The largest impacts on PA stream [Ba] and [SO₄] are related to releases from coal mining or burning rather than oil and gas development.

     

Fossil bog soils (‘<Emphasis Type="Italic">dwog</Emphasis> horizons’) and their relation to Holocene coastal changes in the Jade Weser region,southern North Sea,Germany

After the deceleration of the postglacial marine transgression, the German North Sea coast was subject to deposition of a complex pattern of subtidal to terrestrial facies. This study aims at reconstructing these facies changes in the ‘Land Wursten’ region (Lower Saxony) by focussing on so-called dwog horizons (incipient soil horizons of the pre-engineered salt marshes). We explore their implications for relative sea-level reconstructions and their indication for early settlement activities. Archive drilling data (1960, provided by the ‘Landesamt für Bergbau, Energie und Geologie’) were analysed to create five high-resolution stratigraphic cross sections. Three new drilling records were subjected to sedimentological and microfaunal investigations and interpreted to verify and calibrate the archive data. Two dwog horizons were found and ¹⁴C-AMS dated. We found basal salt marsh deposits inundated by a high-energy event and covered by tidal flat sediments. The thick tidal flat unit is again overlain by salt marsh deposits indicating the transition from a shallow marine to a terrestrial environment where dwogs were developed and covered by episodic marine incursions. The ages of the dwogs (1128–969 cal BC; cal AD 1426–1467) do not correlate with known layers of adjacent settlement sites and are critically discussed. However, we show that they correlate with phases of stagnant regional relative sea level (RSL) and can be used as RSL indicators. The combined archive and modern data provide valuable information for the RSL reconstruction and palaeoenvironmental changes. However, further research is recommended to accomplish more detailed information about coastal response during the Holocene sea-level changes and implications for settlement dynamics.     

Microsatellite analysis of plaice (Pleuronectes platessa L.) in the NE Atlantic: weak genetic structuring in a milieu of high gene flow

Many species of marine fish are typified by large population sizes, strong migratory behavior, high fecundity, and pelagic eggs and larvae that are passively transported by ocean currents, all features that tend to increase gene flow, and hence reduce genetic partitioning, among localized populations. The plaice, Pleuronectes platessa, is a commercially important demersal species that exhibits all of these characteristics. We analyzed genetic variation at eight microsatellite loci in samples of spawning adults (N = 348) from the coasts of Ireland, Iceland, and, for the first time, from the Baltic Sea. Significant differentiation was observed between Iceland and Irish and Baltic Sea samples. However, there were no genetic differences between Irish and Baltic Sea samples, which contrast with the significant differentiation reported between Baltic Sea and North Sea/Atlantic populations of other flatfish species. To increase the data set, we carried out a cross-calibration exercise, allowing us to perform a joint analysis of data with an earlier study on adult and juvenile plaice (N = 480) collected over a broad geographic range, using six microsatellite loci in common to the two studies. Significant differentiation was observed between fish collected at the northern (Iceland, Faeroes, Norway) and southern (Bay of Biscay) parts of the species range. In contrast, the results showed little evidence of genetic structuring over much of the continental shelf of Europe. We believe that bathymetric and hydrographic barriers are the major factors shaping genetic structure, while lack of structure over much of the European continental shelf may be explained by a combination of past historical events, population structure, and dynamics of the species.     

Disappearing plants: why they hide and how they return

Prolonged dormancy is a life-history stage in which mature plants fail to resprout for one or more growing seasons and instead remain alive belowground. Prolonged dormancy is relatively common, but the proximate causes and consequences of this intriguing strategy have remained elusive. In this study we tested whether stored resources are associated with remaining belowground, and investigated the resource costs of remaining belowground during the growing season. We measured stored resources at the beginning and end of the growing season in Astragalus scaphoides, an herbaceous perennial in southwest Montana, USA. At the beginning of the growing season, dormant plants had lower concentrations of stored mobile carbon (nonstructural carbohydrates, NSC) than did emergent plants. Surprisingly, during the growing season, dormant plants gained as much NSC as photosynthetically active plants, an increase most likely due to remobilization of structural carbon. Thus, low levels of stored NSC were associated with remaining belowground, and remobilization of structural carbon may allow for dormant plants to emerge in later seasons. The dynamics of NSC in relation to dormancy highlights the ability of plants to change their own resource status somewhat independently of resource assimilation, as well as the importance of considering stored resources in understanding plant responses to the environment.     

The Relationship Between Critical Flicker Fusion Frequency (CFFF) and Temperamenta Characteristics

he analysis in this paper was based on data obtained from 80 male participants, aged 29-65. Critical Flicker Fusion Frequency (CFFF) was measured using the Flicker Test. The Formal Characteristics of Behaviour-Temperament Inventory (FCB-TI) by Strelau and Zawadzki (1993) was used for temperamental characteristics. The results of statistical analysis did not confirm a hypothesis about the correlation between CFFF level and 3 temperamental characteristics. There were no immediate relationships among those variables. Correlation was observed when the CFFF coefficient of variance, instead of average CFFF values, was taken into account, especially in the case of a division into 2 groups of participants, “reckless” and “unsure.” It could be interesting to check in the future a hypothesis about the stability of selected types of reactions.     

Analysis of Conditions and Organization of Work of Notebook Computer Users

Abstract

Aim. The aim of this study was to evaluate working conditions with a notebook computer (notebook) as a potential cause of musculoskeletal disorders. Material and methods. The study had 2 stages. The first one was a questionnaire survey among 300 notebook users. The next stage was an expert analysis of 53 randomly selected workstations. The questionnaire survey included questions about the participants, their working conditions, work organization and also duration of work with a notebook. Results and conclusions. The results of the research showed that most examined operators used a notebook as a basic working tool. The most important irregularities included an unadjustable working surface, unadjustable height of the seat pan and backrest, unadjustable height and distance between the armrests and no additional ergonomic devices (external keyboard, docking station, notebook stand or footstool).