Search

Start Over Language English

2963. Allium oleraceum in Slovakia: cytotype distribution and ecology

Creator:
Šafářová, Lenka, Duchoslav, Martin, Jandová, Michaela, and Krahulec, František
Type:
article and TEXT
Subject:
Allium, Czech Republic, distribution, flow cytometry, habitat differentiation, polyploidy, spatial scales, and vertical distribution
Language:
English
Description:
The spatial distribution of cytotypes can provide valuable insights into the evolution of polyploid complexes. Previously, only tetraploid Allium oleraceum was reported from Slovakia. Analysing 863 individuals from 93 populations from Slovakia revealed an extensive variation in the DNA ploidy levels of Allium oleraceum (3x, 4x, 5x and 6x). Of the main cytotypes, the penta- and tetraploids had strongly overlapping distributions, although the pentaploids exhibited a tendency to occur more frequently in the southern and the tetraploids had a tendency to occur in the northern regions of Slovakia. A triploid cytotype was found in one population in the southern part of Slovakia, which is the third locality worldwide for this cytotype. The hexaploid cytotype was rare and sparsely occurred in western and southern Slovakia. Sixteen per cent of the populations sampled consisted of more than one ploidy level; the most common was a combination of penta- and tetraploids. The cytotypes differed with respect to altitude; the tetraploids were found significantly more frequently at higher altitudes than the penta- and hexaploids. When compared with reanalysed altitudinal distribution data from the Czech Republic divided into two geographic areas (Carpathian and Herzynian) the pattern found in the Carpathian part of the Czech Republic was similar to that in Slovakia, with tetraploids at the higher altitudes. The distribution in the Herzynian part (Bohemian Massif) was just the opposite: the tetraploids were more often found at lower altitudes than the penta- and hexaploids. Both tetra- and pentaploid cytotypes occurred in a wide and similar spectrum of habitats, while hexaploids were limited to human-influenced habitats. A local-scale distribution of cytotypes analysed in detail in the Slovak Karst area, showed surprising differences in the distribution of cytotypes on particular karst plains, which can be related to different land uses. Concerning the contrasting altitudinal differentiation of tetraploids in the regions compared, the results suggest that at least two different types of tetraploids occur in Central Europe. The apparent cytotype diversity in the surrounding Slovak Karst area may suggest the existence of a primary contact zone.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/

2964. Allopurinol intake does not modify the slow component of V O2 kinetics and oxidative stress induced by severe intensity exercise

Creator:
Olek, R. A., Safranow, K., Jakubowska, K., Olszewska, M., Chlubek, D., and Laskowski, R.
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie člověka, human physiology, xanthine oxidase, total antioxidant status, reactive oxygen species, 14, and 612
Language:
English
Description:
The aim of this study was to test the hypothesis that allopurinol ingestion modifies the slow component of • VO2 kinetics and changes plasma oxidative stress markers during severe intensity exercise. Six recreationally active male subjects were randomly assigned to receive a single dose of allopurinol (300 mg) or a placebo in a double-blind, placebo-controlled crossover design, with at least 7 days washout period between the two conditions. Two hours following allopurinol or placebo intake, subjects completed a 6-min bout of cycle exercise with the power output corresponding to 75 % • VO2 max. Blood samples were taken prior to commencing the exercise and then 5 minutes upon completion. Allopurinol intake caused increase in resting xanthine and hypoxanthine plasma concentrations, however it did not affect the slow component of oxygen uptake during exercise. Exercise elevated plasma inosine, hypoxanthine, and xanthine. Moreover, exercise induced a decrease in total antioxidant status, and sulfhydryl groups. However, no interaction treatment x time has been observed. Short term severe intensity exercise induces oxidative stress, but xanthine oxidase inhibition does not modify either the kinetics of oxygen consumption or reactive oxygen species overproduction., R. A. Olek ... [et al.]., and Obsahuje seznam literatury
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2965. Allosteric activation of yeast enzyme neutral trehalase by Calcium and 14-3-3 Protein

Creator:
Alblova, M. , Smidova, A., Kalabova, D., Lentini Santo, D., Obsil, T., and Obsilova, V.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
14-3-3 protein, Trehalase, Calcium, Trehalose, Allostery, Conformation, Enzyme, and Crystal structure
Language:
English
Description:
Neutral trehalase 1 (Nth1) from Saccharomyces cerevisiae catalyzes disaccharide trehalose hydrolysis and helps yeast to survive adverse conditions, such as heat shock, starvation or oxidative stress. 14-3-3 proteins, master regulators of hundreds of partner proteins, participate in many key cellular processes. Nth1 is activated by phosphorylation followed by 14-3-3 protein (Bmh) binding. The activation mechanism is also potentiated by Ca2+ binding within the EF-hand-like motif. This review summarizes the current knowledge about trehalases and the molecular and structural basis of Nth1 activation. The crystal structure of fully active Nth1 bound to 14-3-3 protein provided the first high-resolution view of a trehalase from a eukaryotic organism and showed 14-3-3 proteins as structural modulators and allosteric effectors of multi-domain binding partners.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

2966. Allosteric modulation of ligand gated ion channels by ivermectin

Creator:
Hana Zemková, Tvrdonová, V., Anirban Bhattacharya, and Marie Jindřichová
Format:
print
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, iontové kanály, ion channels, cys-loop receptor family, purinergic P2X4 receptor, ivermectin, transmembrane domain, 14, and 612
Language:
English
Description:
Ivermectin acts as a positive allosteric regulator of several ligand gated channels including the glutamate-gated chloride channel (GluCl), γ-aminobutyric acid type-A receptor, glycine receptor, neuronal α 7-nicotinic receptor and purinergic P2X4 receptor. In most of the ivermect in-sensitive channe ls, the effects of ivermectin include the potentiation of agonist-induced currents at low concentrations and channel opening at higher concentrations. Based on mutagenesis, electrophysiological recordings and functional an alysis of chimeras between ivermectin-sensitive and ivermectin-insensitive receptors, it has been concluded that ivermectin acts by insertion between transmembrane helices. The three-dimensional structure of C. elegans GluCl complexed with ivermectin has revealed the details of the ivermectin-binding site, however, no generic motif of amino acids could accurately predict ivermectin binding site for other ligand gated channels. Here, we will review what is currently known about ivermectin binding and modulation of Cys-loop receptor family of ligand-gated ion channels and what are the critical structur al determinants underlying potentiation of the P2X4 receptor channel., H. Zemkova ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2967. Allostery and Cooperativity in the Interaction of Drugs with Ionic Channel Receptors

Creator:
Krůšek, J.
Type:
article, model:article, and TEXT
Subject:
Allostery, Cooperativity, Hill coefficient, Affinity, Efficacy, and Nicotinic acetylcholine receptor
Language:
English
Description:
Allostery is an essential property of many physiological mechanisms. Cooperativity together with allostery is observed in the behavior of multisubunit receptors. Here we summarize and compare several approaches to the description and analysis of allosteric phenomena with emphasis on the receptors connected to ionic channels as a model. Several simplified methods are discussed in comparison with the microscopic kinetic scheme, affinity-efficacy separation and a thermodynamic approach.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2968. Alloxan in vivo does not only exert deleterious effects on pancreatic B cells

Creator:
Szkudelski, T., Kandulska, K., and Okulicz, M.
Type:
article, model:article, and TEXT
Subject:
alloxan, glucose, insulin, sulfhydryl groups, and glutathione peroxidase
Language:
English
Description:
The aim of the experiment was to investigate the mechanism of harmful alloxan action in vivo. 75 mg/kg b.w. of this diabetogenic agent were administered to fasting rats. Two minutes later the animals were decapitated. It was observed that alloxan caused a distinct rise in blood insulin and glucose levels with a concomitant drop of free fatty acids. The amount of sulfhydryl groups in the liver of alloxan-treated rats was decreased and glutathione peroxidase activity was substantially higher. These results indicate that some changes observed in alloxan-induced diabetes can not only be the consequence of B cells damage by alloxan but may also be the result of its direct influence on other tissues. It was also observed that glucose given 20 min before alloxan injection only partially protected against the deleterious effects of alloxan.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2969. Allozyme polymorphism in isolated populations of the moth Coenophila subrosea (Lepidoptera: Noctuidae) from three Central European peat bogs

Creator:
Šula, Jan and Spitzer, Karel
Format:
print, text, and regular print
Type:
article, model:article, and TEXT
Subject:
můrovití, genetická variabilita, entomologie, hmyz, motýli, Coenophila subrosea, dospělí samečci, alozymy, alozymový polymorfizmus, populační genetika, morfometrická studie, konzervace, Noctuidae, allozyme variation, population genetics, isolated peat bogs, tyrphobionts, conservation, 592.5/.7, and 591.1
Language:
English
Description:
Allozyme polymorphism was investigated in adult males of the stenotopic peat bog (tyrphobiontic) noctuid moth, Coenophila subrosea Stephens, from three isolated peat bog localities in Austria (Styria) and Czech Republic (South and North Bohemia). Of the eighteen enzyme loci examined, twelve were polymorphic and six monomorphic. Significant deviations of genotype frequencies from Hardy-Weinberg equilibrium were observed at about one third of polymorphic loci within the populations. The average heterozygosities for the populations from three geographically distinct localities ranged from 0.192 to 0.245, and 61% of the loci were polymorphic. The FST mean value of 0.0675 was higher than that found in most other Lepidoptera. The genetic distances based on allozyme heterozygosity ranged from 0.019 to 0.051, with the population from South Bohemia being the most distant. The genetic distances and FST values do not reflect the geographic distances between the populations. Morphometric analysis revealed a difference between the Austrian Purgschachen Moor and Bohemian populations. These isolated relict peat bogs are habitat islands inhabited by unique "geographical races" of tyrphobiontic taxa., Jan Šula, Karel Spitzer, 4 obrázky, 5 tab., and Lit.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

Limit your search

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

View distribution

Current results range from 1701 to 2024

View larger »