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991.
Gabriela Bugla-Płoskońska Jacek Rybka Bożena Futoma-Kołoch Agnieszka Cisowska Andrzej Gamian Włodzimierz Doroszkiewicz 《Microbial ecology》2010,59(3):601-613
Sialic acid (N-acetylneuraminic acid, NeuAc) plays an essential role in protecting gram-negative bacteria against the bactericidal
activity of serum and may contribute to the pathogenicity of bacteria by mimicking epitopes that resemble host tissue components
(molecular mimicry). The role of sialic acid (NeuAc)-containing lipopolysaccharides (LPS) of Salmonella O48 strains in the complement activation of normal human serum (NHS) was investigated. NeuAc-containing lipooligosaccharides
cause a downregulation of complement activation and may serve to camouflage the bacterial surface from the immunological response
of the host. Serotype O48 Salmonella strains have the O-antigen structure containing NeuAc while its serovars differ in outer membrane protein composition. In
this study, the mechanisms of complement activation responsible for killing Salmonella O48 serum-sensitive rods by NHS were established. Four of such mechanisms involving pathways, which are important in the
bactericidal mechanism of complement activation, were distinguished: only the classical/lectin pathways, independent activation
of the classical/lectin or alternative pathway, parallel activation of the classical/lectin and alternative pathways, and
only the alternative pathway important in the bactericidal action of human serum. To further study the role of NeuAc, its
content in bacterial cells was determined by gas-liquid chromatography-mass spectrometry in relation to 3-deoxy-D-manno-2-octulosonic
acid (Kdo), an inherent constituent of LPS. The results indicate that neither the presence of sialic acid in LPS nor the length
of the O-specific part of LPS containing NeuAc plays a decisive role in determining bacterial resistance to the bactericidal
activity of complement and that the presence of sialic acid in the structure of LPS is not sufficient to block the activation
of the alternative pathway of complement. We observed that for three strains with a very high NeuAc/Kdo ratio the alternative
pathways were decisive in the bactericidal action of human serum. The results indicated that those strains are not capable
of inhibiting the alternative pathway very effectively. As the pathogenicity of most Salmonella serotypes remains undefined, research into the interactions between these bacterial cells and host organisms is indispensable. 相似文献
992.
L’ubica Halušková Katarína Valentovičová Jana Huttová Igor Mistrík Ladislav Tamás 《Plant Growth Regulation》2010,62(1):59-64
All of the analyzed heavy metals significantly inhibited root growth, but in addition to Cd exposure an elevated IAA-POD activity
was detected under Co, Cu and Hg treatment, while Ni and Pb inhibited its activity. The Cd-induced IAA-POD activity increased
from the root apex towards to the mature region of root tips. However similar or even more severe root growth inhibition was
observed by exogenously applied IAA, IAA-POD activity was activated only at high IAA concentrations. Elevated Cd-induced H2O2 production was detected both in the absence or in the presence of IAA in the reaction mixture, but in the case of IAA as
a possible substrate for PODs the production of H2O2 increased markedly just in the Cd-treated roots. Exogenously applied H2O2 also activated IAA-POD activity. Our results indicated that in the development of Cd toxicity syndrome the production of
ROS during IAA degradation by elevated IAA-POD activity plays a crucial role, mainly under severe Cd stress. 相似文献
993.
Due to insufficient morphological differentiation, hybridization among linear‐leaved species of Potamogeton is rarely observed and recognized. Here, we applied molecular tools (sequencing of nrITS and rpl32‐trnL cpDNA intergenic spacer) to study several natural, central European populations of morphologically intermediate forms between two closely related species, P. acutifolius and P. compressus, to examine their taxonomical status and test whether they represented the variation range of the species or are results of interspecific hybridization. Both DNA regions provided distinguishing characters between putative parental species. The ITS sequences from all the morphologically intermediate specimens displayed an additive pattern combining the variation of both parental species, providing evidence for the hybrid origin of all these plants. This case study suggests that hybrids of linear‐leaved Potamogeton species are more common than usually believed, but have been difficult to identify without molecular tools. 相似文献
994.
L’ubica Halušková Katarína Valentovičová Jana Huttová Igor Mistrík Ladislav Tamás 《Acta Physiologiae Plantarum》2010,32(1):59-65
In the present work, we investigated the alteration of oxidative and peroxidative activities of peroxidases (PODs) along the longitudinal root axis of barley seedlings during heavy metal (HM; e.g., Cd, Cu, Hg, Ni, Pb) treatment. Analysis of the individual root segments revealed that all of the analyzed HMs caused an increase of guaiacol-POD activity, however to a different extent and spatial distribution. Cd-induced ferulic acid POD activity was observed along the whole root tip (RT), while Cu and Hg caused its increase in the meristematic zone and Ni mainly at the end of the differentiation zone of RT. The activation of coniferyl alcohol POD by HMs was detected along the whole RT. HM-induced hydrogen peroxide-generating POD activity was localized mainly to the elongation zone of RT. Elevated chlorogenic acid POD activity was observed in the meristematic zone and at the end of the differentiation zone of RTs. The activation of several PODs is probably associated with enhanced H2O2 production and lignification as a defense response of roots to several HM, to prevent their uncontrolled flux. On the other hand, this defense response is accompanied by root growth inhibition, due to the enhanced rigidification of cell wall and accelerated differentiation of RTs. 相似文献
995.
Zbigniew Szybiński Stanisław Walas Paweł Zagrodzki Grzegorz Sokołowski Filip Gołkowski Halina Mrowiec 《Biological trace element research》2010,138(1-3):28-41
The purpose of this work was to determine trace element levels in urine and evaluate possible associations between urinary iodine concentration (UIC), other trace elements (Cr, Cu, Fe, Mn, Na, Se, Zn), toxic elements (Cd, Pb), anthropometrical measures (body weight and height), glycemic indices (serum insulin and glucose), and several parameters related to thyroid function (thyroid stimulating hormone, free thyroxine, antithyroid peroxidase antibodies, thyroid volume, and thyroid echogenicity) in pregnant women. One hundred sixty-nine participants were recruited. The whole study group, originating from Krakow region, comprised three subgroups belonging to three trimesters: I trimester (n?=?28), II trimester (n?=?83), and III trimester (n?=?58). Trace elements were determined using inductively coupled plasma mass/(atomic emission) spectrometry. Partial least square model was used to reveal correlation structure between parameters investigated, as well as a possible causal relationship between dependent parameters and potentially explanatory parameters. Results obtained for trace and toxic elements in urine were comparable with results of other authors, although the study group was not homogenous. We confirmed (1) low iodine excretion in pregnant women, (2) the existence of statistically significant correlation between UIC and urinary selenium, and (3) lack of correlation between latter parameter and typical indices of thyroid function. Urinary selenium correlated with other urinary trace elements, but physiological significance of this finding remains uncertain. The fact that a large number of pregnant women fail to meet dietary recommendations for iodine is the major reason for concern. 相似文献
996.
Iwona Błaszczyk Ewa Grucka-Mamczar Sławomir Kasperczyk Ewa Birkner 《Biological trace element research》2010,133(1):60-70
The intensified or uncontrolled formation of reactive oxygen species leads to disturbances of numerous biochemical processes.
Among the factors inducing intensified free radical processes, fluoride ions are listed, among others. One of the organs most
exposed to the toxic activity of fluorides is the kidney. In the study presented here, the influence of fluorine upon the
activity of selected antioxidant enzymes in rat kidney has been examined, as well as antioxidant properties of methionine
during intoxication with sodium fluoride. The experiment was carried out on Wistar FL rats (adult females) that for 35 days
were administered water, NaF, NaF with methionine (doses: 10 mg NaF/kg bw/day, 10 mg Met/kg bw/day) . The influence of administered
NaF and Met upon the antioxidative system in kidney was examined by analyzing the activity of the most important antioxidative
enzymes (SOD, CAT, GPX, GR, GST). The studies carried out confirmed the disadvantageous effect of NaF upon the antioxidative
system in rats (decrease in activity of antioxidative enzymes). Methionine increased the activity of antioxidative enzymes,
most efficiently that of GPX, GR, and GST. 相似文献
997.
El?bieta ?odyga-Chru?cińska El?bieta Sochacka Longin Chru?ciński Daniele Sanna Monika G?siorkiewicz 《Journal of inorganic biochemistry》2010,104(5):570-575
Copper(II) complexes of histamine modified 2′-deoxyriboadenosine (N-[(9-β-D-2′-deoxyribofuranosylpurin-6-yl)-carbamoyl]histamine) ligand were studied by potentiometric, UV-visible and EPR techniques. The imidazole residue of the ligand was described as the main binding site forming mono-, bis-(ligand) and dimer complexes, but the interactions between adenosine nitrogen N(1) and carbamoyl nitrogen atoms and the copper(II) ion also were detected. This is the first report evaluating the coordinating ability of such a modified adenosine ligand towards copper(II) ion. Our findings suggest that histamine modified 2′-deoxyriboadenosine could chelate efficiently copper(II) ions if it were incorporated into DNAzyme sequence. 相似文献
998.
Sławomir Tubek Andrzej Bunio Renata Szyguła Alina Tubek 《Biological trace element research》2010,133(3):243-250
The content of elements in rainwater is an indirect indicator of its occurrence in air dust. This is sometimes referred to
as rain fallout and is investigated in applied environmental pollution monitoring schemes. The annual content of elements
in rainwater may be recognized as good index for assessing influence of those environmental factors on human body. The possible
relationship between the concentrations of selected elements in rainwater and the frequency of hospitalization by reason of
angina pectoris, stroke, and peripheral venous thrombosis was investigated in the Opole Voivodship (Poland) area during the
period 2000–2002. There is a relatively high or partly significant correlation between frequency of hospitalization by reason
of these conditions and content of lead, cadmium, chromium, zinc, and chloride in rainwater. Significant gender-dependent
differences were observed only in peripheral venous thrombosis, where important correlations with lead, cadmium, and chromium
were found only in men. 相似文献
999.
The authors present a study of the fluorescence and absorbance transients occurring in whole cells of purple nonsulfur bacterium
Rhodobacter sphaeroides on the millisecond timescale under pulsed actinic illumination. The fluorescence induction curve is interpreted in terms
of combination of effects of redox changes in the reaction center and the membrane potential. The results of this study support
the view that the membrane potential act predominantly to increase the fluorescence yield. Advantages of the pulsed actinic
illumination for study of the operation of the electron transport chain in vivo are discussed. 相似文献
1000.