Evidence for an increased distribution range of Dermacentor reticulatus in south-west Poland

The expansion of Dermacentor reticulatus to new geographical areas has been observed in several countries in Europe, including Poland and it’s neighbors. In 2011 and 2012, a total of 148 host-seeking D. reticulatus ticks were collected after flagging the vegetation in Lower Silesia, south-western Poland. Tick monitoring was conducted in mixed and deciduous forest, on meadows, in river valleys and ecotones between forested and grassy areas. The ornate dog ticks were found in 10 out of 33 sites located in five districts: Legnica, Wroclaw, ?roda ?l?ska, Lubin and Boleslawiec County. All sites where D. reticulatus ticks were found are located to the south-west of the Odra River. The greatest distance between these disconnected localities was approximately 90 km. It seems that at present the southern boundary of the range is Wroclaw district. This study indicates that D. reticulatus can be ranked as a typical element of the fauna in Lower Silesia in southwestern Poland.     

Accumulation of cesium and radiocesium in forest litter in selected regions of poland and its influence on litter-to-mushroom transfer factor

The aim of this work was to check whether the stable cesium content in forest litter affects the value of radiocesium from litter-to-mushroom transfer factorTf or not. Total cesium in litter, measured by AAS, varied from 0.1–2.7 μg/g. These data, combined with earlier results for mushrooms, showed no simple correlation forTf. More complex relationships provided very high correlation coefficients, but their validity needs further investigation.     

Long-range conformational transition in yeast tRNAPhe, induced by the Y-base removal and detected by chloroacetaldehyde modification.

Chemical modification was used to study the conformational changes occurring in yeast tRNAPhe after the Y-base excision. The chemical probe was the adenine- and cytosine-specific reagent chloroacetaldehyde. Comparison of the modification patterns in tRNAPhe and tRNAPhe-Y shows that seven bases, adenines 35, 36 and 38 in the anticodon loop and adenines 73, 76 and cytosines 74, 75 in the 3'-terminus were modified in both tRNAs with a quantitative difference in the modification level of the anticodon loop bases. The most interesting, however, is the qualitative difference consisting in modification of cytosine-60 in the T psi C loop of tRNAPhe-Y. Some aspects of the mechanism of this long-distance conformational transition are briefly discussed.     

Higher seed size and germination rate may favour autotetraploids of Vicia cracca L. (Fabaceae)

The phenotypic effect of increased cell size in polyploid angiosperms has been repeatedly described; the ecological consequences of the gigas effect are, however, relatively poorly understood. Here, we investigated the effect of cytotype, seed weight, and inter‐population variation on seedling germination and growth in diploid and autotetraploid Vicia cracca L. in a common garden experiment. Seeds used in this study originated in the contact zone of the cytotypes in Central Europe. Tetraploids had heavier seeds than diploids and greater germination rates irrespective of seed size. Both seed weight and germination rate displayed high inter‐population variation. Further, tetraploids seem to germinate earlier and deposit fewer reserves into the seed bank than diploids. Mean above‐ground biomass and seedling height were similar in the two cytotypes of V. cracca. Nonetheless, the tallest tetraploid seedlings were taller than the tallest diploid seedlings, which may be advantageous under strong competition in dense vegetation. This study thus demonstrates that tetraploids of V. cracca may have superior competitive ability to diploids in certain habitats. It also suggests the necessity of studying multiple populations per cytotype when comparing diploids and polyploids, as the effect of population may be of similar or even higher magnitude than the effect of cytotype. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 113 , 57–73.     

Vanadate inhibits the production and/or release of secondary metabolites without impairing growth in several fungal species

Vanadate (NaVO₃) in concentrations between 0.1–3.0 mmol/L inhibited the production of secondary metabolites (SMs) of strains of the following species:Trichoderma viride, Penicillium purpurogenum, Penicillium citrinum, Talaromyces avellaneus, andVerticillium psalliotœ. Growth was either not affected by NaVO₃, or the inhibition of the SM production occurred at lower NaVO₃, concentrations than that of the growth. Thus, at some NaVO₃ concentration the SM production was inhibited but the growth remained unaffected. The results suggest that NaVO₃ exerts a specific action either on the SM biosynthetic pathway(s) or on the export of SMs from cells.     

The influence of β-cyclodextrin on the kinetics of progesterone transformation by Rhizopus nigricans

The process of progesterone 11α-hydroxylation by the pelleted growth form of the filamentous fungus Rhizopus nigricans has been described with a mathematical model, based on Michaelis-Menten enzyme kinetics and the rate of substrate dissolution. It was confirmed that the low water solubility of steroids is the limiting step of this process at high steroid concentrations. In order to overcome this problem, β-cyclodextrin, which is known to form inclusion complexes with these organic compounds, was added to the production medium. The phase solubility of the steroid-β-cyclodextrin system was investigated and the effect of β-cyclodextrin addition on progesterone biotransformation evaluated. Enhancement of steroid solubility was demonstrated and nearly two-fold increase in reaction rate was found in the presence of β-cyclodextrin.     

Long-term effects of dietary glycemic index on adiposity, energy metabolism, and physical activity in mice

A high-glycemic index (GI) diet has been shown to increase adiposity in rodents; however, the long-term metabolic effects of a low- and high-GI diet have not been examined. In this study, a total of 48 male 129SvPas mice were fed diets high in either rapidly absorbed carbohydrate (RAC; high GI) or slowly absorbed carbohydrate (SAC; low GI) for up to 40 wk. Diets were controlled for macronutrient and micronutrient content, differing only in starch type. Body composition and insulin sensitivity were measured longitudinally by DEXA scan and oral glucose tolerance test, respectively. Food intake, respiratory quotient, physical activity, and energy expenditure were assessed using metabolic cages. Despite having similar mean body weights, mice fed the RAC diet had 40% greater body fat by the end of the study and a mean 2.2-fold greater insulin resistance compared with mice fed the SAC diet. Respiratory quotient was higher in the RAC group, indicating comparatively less fat oxidation. Although no differences in energy expenditure were observed throughout the study, total physical activity was 45% higher for the SAC-fed mice after 38 wk of feeding. We conclude that, in this animal model, 1) the effect of GI on body composition is mediated by changes in substrate oxidation, not energy intake; 2) a high-GI diet causes insulin resistance; and 3) dietary composition can affect physical activity level.     

Calcium and magnesium competitively influence the growth of a PMR1 deficient Saccharomyces cerevisiae strain

PMR1, the Ca2+/Mn2+ ATPase of the secretory pathway in Saccharomyces cerevisiae was the first member of the secretory pathway Ca2+ ATPases (SPCA) to be characterized. In the past few years, pmr1Delta yeast have received more attention due to the recognition that the human homologue of this protein, hSPCA1 is defective in chronic benign pemphigus or Hailey-Hailey disease (HHD). Recent publications have described pmr1Delta S. cerevisiae as a useful model organism for studying the molecular pathology of HHD. Some observations indicated that the high Ca2+ sensitive phenotype of PMR1 defective yeast strains may be the most relevant in this respect. Here we show that the total cellular calcium response of a pmr1Delta S. cerevisiae upon extracellular Ca2+ challenge is decreased compared to the wild type strain similarly as observed in keratinocytes. Additionally, the novel magnesium sensitivity of PMR1 defective yeast is revealed, which appears to be a result of competition for uptake between Ca2+ and Mg2+ at the plasma membrane level. Our findings indicate that extracellular Ca2+ and Mg2+ competitively influence the intracellular Ca2+ homeostasis of S. cerevisiae. These observations may further our understanding of HHD.     

A survey of metronidazole and vancomycin resistance in strains of Clostridium difficile isolated in Warsaw, Poland

The drug of choice used to treat Clostridium difficile-associated diarroea (CDAD) are metronidazole and vancomycin. Information about emergence of antimicrobial resistance among C. difficile strains to metronidazole and intermediate resistance to vancomycin in some countries are alarming. This study was performed to determine the susceptibility to metronidazole and vancomycin of 193 C. difficile strains isolated in our diagnostic laboratory between year 1998 and 2003 from patients adults and children suffering from CDAD. Among these strains, 142 produced toxin A and B (TcdA(+)TcdB(+)), 43 only B (TcdA(-)TcdB(+)) and 8 were nontoxigenic. We have not observed any differences in susceptibility to metronidazole and vancomycin between all C. difficile strains under investigation (toxinogenic and non-toxinogenic). Resistance to metronidazole and vancomycin was not observed.