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51.
CMA Iwegbue OV Beecroft JE Ogala FE Egobueze GO Tesi GE Nwajei 《African Journal of Aquatic Science》2018,43(3):241-253
The concentrations of nine metals were measured by atomic absorption spectrophotometry in surface sediments of three coastal creeks, namely, the Ifie, Egbokodo and Ubeji creeks, in the Niger Delta of Nigeria, from August 2012 to January 2013. The aim of the study was to provide information on the spatial and seasonal distribution patterns, degree of contamination, and ecological risks of metals in these sediments. The mean concentrations of the nine metals in these creek sediments ranged from 0.30 to 3.20?mg kg?1 Cd; 10.7 to 24.7?mg kg?1 Pb, 125 to 466?mg kg?1 Cr; 3.1.10 to 14.9?mg kg?1 Cu; 4.7 to 14.3?mg kg?1 Co; 61.1 to 115?mg kg?1 Ni; 106 to 183?mg kg?1 Mn; 52.0 to 170?mg kg?1 Zn and 5 469 to 20 639?mg kg?1 Fe. In general, the metal concentrations were higher in the dry season than the wet season, except for Cr. The concentrations of Cd, Cr, Ni and Zn were above their regulatory control limits in sediment as specified by the Nigerian Regulatory Authority and Cd was identified as the main ecological risk factor. The enrichment factors for the studied metals followed the order: Cd > Cr > Ni > Zn > Pb > Co > Mn > Cu. The average multiple pollution index values indicated that these sediments were severely polluted with significant inputs from Cd, Ni and Cr. 相似文献
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ANDREA BEDNÁŘOVÁ NATRAJ KRISHNAN I‐CHENG CHENG JOSEF VEČEŘA HOW‐JING LEE DALIBOR KODRÍK 《Physiological Entomology》2013,38(1):54-62
The role of adipokinetic hormone (AKH) in counteracting oxidative stress elicited in the insect body is studied in response to exogenously applied hydrogen peroxide, an important metabolite of oxidative processes. In vivo experiments reveal that the injection of hydrogen peroxide (8 µmol) into the haemocoel of the firebug, Pyrrhocoris apterus L. (Heteroptera: Pyrrhocoridae) increases the level of AKH by 2.8‐fold in the central nervous system (CNS) and by 3.8‐fold in the haemolymph. The injection of hydrogen peroxide also increases the mortality of experimental insects, whereas co‐injection of hydrogen peroxide with Pyrap‐AKH (40 pmol) reduces mortality to almost control levels. Importantly, an increase in haemolymph protein carbonyl levels (i.e. an oxidative stress biomarker) elicited by hydrogen peroxide is decreased by 3.6‐fold to control levels when hydrogen peroxide is co‐injected with Pyrap‐AKH. Similar results are obtained using in vitro experiments. Oxidative stress biomarkers such as malondialdehyde and protein carbonyls are significantly enhanced upon exposure of the isolated CNS to hydrogen peroxide in vitro, whereas co‐treatment of the CNS with hydrogen peroxide and Pyrap‐AKH reduces levels significantly. Moreover, a marked decrease in catalase activity compared with controls is recorded when the CNS is incubated with hydrogen peroxide. Incubation of the CNS with hydrogen peroxide and Pyrap‐AKH together curbs the negative effect on catalase activity. Taken together, the results of the present study provide strong support for the recently published data on the feedback regulation between oxidative stressors and AKH action, and implicate AKH in counteracting oxidative stress. The in vitro experiments should facilitate research on the mode of action of AKH in relation to oxidative stress, and could help clarify the key pathways involved in this process. 相似文献
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V. L. Akhmetova R. I. Khusainova E. B. Yuryev I. A. Tuktarova N. V. Petrova S. V. Makarov O. I. Kravchuk G. V. Pai E. V. Balanovskaya E. K. Ginter E. K. Khusnutdinova 《Russian Journal of Genetics》2006,42(2):192-207
Population genetic survey of the indigenous populations of the Marii El Republic, represented by the two major ethnographic groups of Maris, Meadow (five samples from Morkinsk, Orshansk, Sernursk, Sovetsk, and Zvenigovsk districts) and Mountain (one sample from Gornomariisk district) Maris, was carried out. All Mari groups were examined at nine polymorphic DNA loci of nuclear genome, VNTR(PAH) (N=422), STR(PAH) (N=152), VNTR(ApoB) (N=294), VNTR(DAT1) (N=363), VNTR(eNOS) (N=373), ACE (N=412), IVS6aGATT (N=513), D7S23(KM.19) (N=494), and D7S8 (N=366). Allele and genotype frequency distribution patterns were obtained for individual samples and ethnographic groups, as well as for the ethnic group overall. In each of six Mari samples examined, the deficit of heterozygotes was observed, i.e., the mean observed heterozygosity was lower than the expected one. The indices of mean heterozygosity, $\bar H_S = 0.455$ , and interpopulation differentiation, $\bar F_{ST} = 0.0024$ , for the Mari gene pool were obtained using a set of DNA markers analyzed. The highest level of interpopulation differentiation is characteristic of ACE loci (F ST=0.0104) and D7S23(KM.19/PstI) (F ST=0.0123). Analysis of the genetic distances and interpopulation differentiation (F ST) showed that the main part of genetic diversity in Maris was determined by the differentiation between the populations of Meadow Maris. The contribution of the differences between the ethnographic groups of Mountain and Meadow Maris to the ethnic gene pool was small. It is suggested that the main role in the formation of the Mari gene pool is played by the geographic factor. 相似文献
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The mechanism of action of β-aminobutyric acid (BABA) as an inducer of resistance to the necrotrophic fungi Botrytis spp. in three different varieties of onion (Allium cepa) is investigated. It is shown that low concentrations of BABA are capable of inducing resistance in onion to neck rot induced by Botrytis allii and that induced by B. cinerea. By means of fluorescence microscopy it is established that treatment of the bulb of onion with BABA leads to priming defensive callose deposition, the principal mechanical barrier against penetration of the pathogen. However, the priming response was not discovered in the Sterling onion variety, which does not exhibit BABA-induced resistance to Botrytis fungi. 相似文献
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The instantaneous state of a neural network consists of both the degree of excitation of each neuron the network is composed of and positions of impulses in communication lines between the neurons. In neurophysiological experiments, the neuronal firing moments are registered, but not the state of communication lines. But future spiking moments depend essentially on the past positions of impulses in the lines. This suggests, that the sequence of intervals between firing moments (inter-spike intervals, ISIs) in the network could be non-Markovian. 相似文献
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Michail I. Gladyshev Nadezhda N. Sushchik Andzhela A. Kolmakova Galina S. Kalachova Elena S. Kravchuk Elena A. Ivanova Olesia N. Makhutova 《Aquatic Ecology》2007,41(1):9-23
The elemental and fatty acid composition of seston was studied for 3 years, from May to October, in a small Reservoir. Under
comparatively low C:P ratio, multivariate canonical analysis revealed no straightforward simple correlations between phosphorus
and single ω3 PUFA species, but complex significant interaction between elemental composition (stoichiometry) of seston and
total sestonic ω3 PUFA as a whole. Since sestonic C, P and N were found to originate mostly from phytoplankton, the contents
of particulate elements and PUFA were attributed to single species in periods of their pronounced dominance. Phytoplankton
species of genera of Stephanodiscus, Peridinium, Gomphosphaeria, Planktothrix and Anabaena in periods of their pronounced dominance had relatively constant species-specific elemental and PUFA composition. Phytoplankton
species significantly differed in their elemental and PUFA composition, as well as in ratios of C:N, N:P, PUFA:P and partly
C:P that indicate food quality for zooplankton. Hence, there were no phytoplankton species of clearly high or low nutritional
value. All of phytoplankters, or at least detritus, that originated from them, may meet specific elemental and biochemical
requirements of specific groups of zooplankton. Dividing phytoplankton on basis of their elemental and biochemical composition,
i.e., nutrition quality, into large taxa (cyanobacteria, diatoms, etc.) appeared to be too coarse for assessing nutritional
value for zooplankton. 相似文献
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OV Salata 《Journal of nanobiotechnology》2007,5(1):5-2
Nanotechnology in Therapeutics: Current Technology and Applications, Edited by Nicholas A. Peppas, J. Zach Hilt and J. Brock
Thomas (Horizon Bioscience, 2007) contains seventeen chapters written by leading specialists in the field of polymeric materials
for drug delivery and holds wealth of background as well as state of the art material divided into four sections: "Intelligent
Therapeutics and Responsive Delivery Systems for Improved Absorption and Delivery", "Therapeutic Micro- and Nanodevices",
"Nanostructured Therapeutic Materials" and "Nanoparticulate Systems in Intelligent Therapy". This newly published volume provides
a stimulating read and a good point of reference to researchers wishing to explore the interdisciplinary fusion of nnanotechnology
and medical therapeutics. The following gives brief summary and critically reviews the book. 相似文献
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