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51.
Snakes elicit a higher level of fear than other vertebrate animals, yet specific cues responsible for fear of snakes are equivocal. The bright colouration hypothesis suggests that fear responses to snakes are triggered by aposematic colouration, not by snakes per se. We investigated the role of aposematic colouration in fear of snakes in a sample of 10- to 15-year-old Slovak children. Both aposematically and cryptically coloured snakes presented as both colour and black-and-white pictures received higher perceived fear scores than other vertebrates. This suggests that aposematic colouration does not play a crucial role in eliciting fear of snakes. Our results support the snake detection theory suggesting that the human visual system has been influenced by long coexistence between predatory snakes and mammals. As a result, humans have evolved an attentional bias ultimately focused on the correct and rapid detection of these threats. 相似文献
52.
Magdalena Semla Pavol Schwarcz Ján Mezey Łukasz J. Binkowski Martyna Błaszczyk Grzegorz Formicki Agnieszka Greń Robert Stawarz Peter Massanyi 《Biological trace element research》2018,184(1):33-41
Wine consumption delivers macroelements and microelements necessary for the proper metabolism. On the other hand, wine can be an important source of toxic metals. The aim of this study was to estimate the concentrations of Ca, Cd, Cu, Fe, Hg, Mg, Ni, Pb, and Zn in the Slovak and non-Slovak wines. The concentration of metals was evaluated with respect to the type, the alcohol content, and the age of Slovak wine. The general scheme of concentrations found was as follows Ca > Mg > Fe > Zn > Pb > Cd > Ni > Cu > Hg. The type of wine and the alcohol content do not have a significant impact on metal concentrations. Also, the age of wine has no influence on the mean concentration of metals, except for Zn. Metal concentrations in Slovak and non-Slovak wines indicate similar contents of metals, except for Ni. The contribution to both dietary reference values (DRVs) and provisional tolerable weekly intake (PTWI) evaluations in the Slovak wine suggested low dietary exposure to Ca, Cu, Fe, Mg, Ni, Zn, Cd, Hg, and Pb, respectively. However, we do not suggest that the consumption of all Slovak wines is healthy. The maximum Pb concentrations in Slovak wines exceed the maximum permitted level proposed by the European Commission. This might be proved by the results of the margin of the exposure (MOE) value evaluation in the samples containing the maximum Pb concentrations, showing a high risk of CKD and SBP in high and extreme consumption groups. 相似文献
53.
The title oligosaccharides, the tri-through the hexasaccharide in the Inaba series and the penta- and the hexasaccharide in the Ogawa series, have been synthesized using 1-thioglycosides of precursors to 3-O-benzyl-perosamine (4-amino-4,6-dideoxy-
-mannose) as building blocks and N-iodosuccinimide/silver triflate as a promoter. The azido groups in the assembled oligosaccharides were reduced to amino groups, which were then acylated using
acid as the derivatizing reagent. Catalytic hydrogenolysis, simultaneously of the benzyl and benzylidene groups, gave the desired products that were characterized by 1H and 13C NMR spectroscopy. 相似文献
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54.
Partial hydrolysis with acid, methylation analysis (including uronic acid degradation), Smith degradation, and p.m.r. spectroscopy have been used to determine the primary structure of the capsular polysaccharide of Klebsiella serotype k64. The hexasaccharide repeating-unit, which also contains one O-acetyl substituent, comprises a 4)-α-d-GlcpA-(1 → 3)-α-d-Manp-(1 → 3)-β-d-Glcp-(1 → 4)-α-d-Manp-(1 → chain with a 4,6-O-(l-carboxyethylidene)-β-d-glucopyranosyl and an l-rhamnosyl group attached to the 4-linked d-mannosyl residue at O-2 and O-3, respectively. 相似文献
55.
Why do flowers close at night? Experiments with the Lesser celandine Ficaria verna Huds (Ranunculaceae) 下载免费PDF全文
Pavol Prokop Peter Fedor 《Biological journal of the Linnean Society. Linnean Society of London》2016,118(3):698-702
Although the mechanisms of flower closure have been widely studied, the evolutionary processes underlying this phenomenon are largely unknown. Open flowers may face a trade‐off between successful pollination/pollen transfer on the one hand and destruction of reproductive organs caused by exogenous factors (e.g. rain) on the other. The cost of flower opening was investigated by treating flowers of the Lesser celandine both in the field and under laboratory conditions. No differences were found in anthesis and reproductive success between treated and untreated flowers in any of the experiments. However, treated flowers in the field experiment suffered from significantly higher predation rates, in all probability caused by slugs and roe deer. It is suggested that flower closure may decrease the rate of being eaten by some herbivores, particularly in early‐spring plants that flower at times of insufficient food availability. 相似文献
56.
Research has shown that hands-on activities in biology/science education tend to improve children’s attitudes towards science. These hands-on activities can influence children’s interest in various ways, perhaps because they invoke varying emotions. We used a sample of 10–12-year-old children (n = 142) to examine the effect of hands-on activities with living snails on children’s achievements and disgust sensitivity. Children with living snails received significantly higher knowledge scores about snails measured with both a knowledge test and with analyses of drawings as compared with control children who received a traditional lecture without living snails. Disgust sensitivity was significantly lower in the experimental group and children who scored higher on the disgust scale received a lower knowledge test score. It would seem that the emotion of disgust negatively correlates with achievement. 相似文献
57.
Lenka?Macková Petr?Vít ?uba??uri?ová Pavol?Eliá?Jr Tomá??UrfusEmail author 《Plant Systematics and Evolution》2017,303(4):481-495
Prunus fruticosa is a rare shrub occurring in Eurasian thermophilous forest-steppe alliances. The species frequently hybridizes with cultivated Prunus species in Europe (allochthonous tetraploid P. cerasus and partly indigenous diploid P. avium). Propidium iodide flow cytometry, distance-based morphometrics, elliptic Fourier analysis and embryology were employed to evaluate the extent of hybridization in six Slovak populations. Flow cytometric analyses revealed three ploidy levels: diploid (P. avium), triploid (P. × mohacsyana) and tetraploid (P. fruticosa, P. × eminens and P. cerasus). In addition, P. fruticosa and P. cerasus, at the tetraploid level, were found to differ in absolute genome size. An embryological evaluation suggested the existence of a triploid block in P. × mohacsyana and significant potential for hybridization among tetraploid taxa (indicated also by a continuous distribution of genome size data and further mirrored by morphometrics). Although hybrids significantly differ in ploidy level and embryological characteristics, they are almost indistinguishable using morphological characters. Hybridization with P. cerasus thus turns out to be a significant threat to wild populations of P. fruticosa compared to the relatively weak influence of P. avium. 相似文献
58.
Norbert Ku?erka Jana Gallová Daniela Uhríková Pavol Balgavy Monica Bulacu Siewert-Jan Marrink John Katsaras 《Biophysical journal》2009,97(7):1926-1932
We have studied the structural properties of monounsaturated diacylphosphatidylcholine lipid bilayers (i.e., diCn:1PC, where n = 14, 16, 18, 20, 22, and 24 is the number of acyl chain carbons). High-resolution x-ray scattering data were analyzed in conjunction with contrast-varied neutron scattering data using a technique we recently developed. Analyses of the data show that the manner by which bilayer thickness increases with increasing n in monounsaturated diacylphosphatidylcholines is dependent on the double bond's position. For commonly available monounsaturated diacylphosphatidylcholines, this results in the nonlinear behavior of both bilayer thickness and lipid area, whereas for diC18:1PC bilayers, lipid area assumes a maximum value. It is worthwhile to note that compared to previous data, our results indicate that lipid areas are smaller by ∼10%. This observation highlights the need to revisit lipid areas, as they are often used in comparisons with molecular dynamics simulations. Moreover, simulators are encouraged to compare their results not only to x-ray scattering data, but to neutron data as well. 相似文献
59.
Folding of the cocaine aptamer studied by EPR and fluorescence spectroscopies using the bifunctional spectroscopic probe Ç 下载免费PDF全文
The cocaine aptamer is a DNA molecule that binds cocaine at the junction of three helices. The bifunctional spectroscopic probe Ç was incorporated independently into three different positions of the aptamer and changes in structure and dynamics upon addition of the cocaine ligand were studied. Nucleoside Ç contains a rigid nitroxide spin label and can be studied directly by electron paramagnetic resonance (EPR) spectroscopy and fluorescence spectroscopy after reduction of the nitroxide to yield the fluoroside Çf. Both the EPR and the fluorescence data for aptamer 2 indicate that helix III is formed before cocaine binding. Upon addition of cocaine, increased fluorescence of a fully base-paired Çf, placed at the three-way junction in helix III, was observed and is consistent with a helical tilt from a coaxial stack of helices II and III. EPR and fluorescence data clearly show that helix I is formed upon addition of cocaine, concomitant with the formation of the Y-shaped three-way helical junction. The EPR data indicate that nucleotides in helix I are more mobile than nucleotides in regular duplex regions and may reflect increased dynamics due to the short length of helix I. 相似文献
60.