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991.
In this study, we examined the modulation of Cu toxicity-induced oxidative stress by excess supply of iron in Zea mays L. plants. Plants receiving excess of Cu (100 μM) showed decreased water potential and simultaneously showed wilting in the
leaves. Later, the young leaves exhibited chlorosis and necrotic scorching of lamina. Excess of Cu suppressed growth, decreased
concentration of chloroplastic pigments and fresh and dry weight of plants. The activities of peroxidase (EC 1.11.1.7; POD),
ascorbate peroxidase (EC 1.11.1.11; APX) and superoxide dismutase (EC 1.15.1.1; SOD) were increased in plants supplied excess
of Cu. However, activity of catalase (EC 1.11.1.6; CAT), was depressed in these plants. In gel activities of isoforms of POD,
APX and SOD also revealed upregulation of these enzymes. Excess (500 μM)-Fe-supplemented Cu-stressed plants, however, looked
better in their phenotypic appearance, had increased concentration of chloroplastic pigments, dry weight, and improved leaf
tissue water status in comparison to the plants supplied excess of Cu. Moreover, activities of antioxidant enzymes including
CAT were further enhanced and thiobarbituric acid reactive substance (TBARS) and H2O2 concentrations decreased in excess-Fe-supplemented Cu-stressed plants. In situ accumulation of H2O2, contrary to that of O2
·− radical, increased in both leaf and roots of excess-Cu-stressed plants, but Cu-excess plants supplied with excess-Fe showed
reduced accumulation H2O2 and little higher of O2
·− in comparison to excess-Cu plants. It is, therefore, concluded that excess-Cu (100 μM) induces oxidative stress by increasing
production of H2O2 despite of increased antioxidant protection and that the excess-Cu-induced oxidative damage is minimized by excess supply
of Fe. 相似文献
992.
Jasmin Léveillé Massimiliano Versace Stephen Grossberg 《Journal of computational neuroscience》2010,28(2):323-346
How spiking neurons cooperate to control behavioral processes is a fundamental problem in computational neuroscience. Such
cooperative dynamics are required during visual perception when spatially distributed image fragments are grouped into emergent
boundary contours. Perceptual grouping is a challenge for spiking cells because its properties of collinear facilitation and
analog sensitivity occur in response to binary spikes with irregular timing across many interacting cells. Some models have
demonstrated spiking dynamics in recurrent laminar neocortical circuits, but not how perceptual grouping occurs. Other models
have analyzed the fast speed of certain percepts in terms of a single feedforward sweep of activity, but cannot explain other
percepts, such as illusory contours, wherein perceptual ambiguity can take hundreds of milliseconds to resolve by integrating
multiple spikes over time. The current model reconciles fast feedforward with slower feedback processing, and binary spikes
with analog network-level properties, in a laminar cortical network of spiking cells whose emergent properties quantitatively
simulate parametric data from neurophysiological experiments, including the formation of illusory contours; the structure
of non-classical visual receptive fields; and self-synchronizing gamma oscillations. These laminar dynamics shed new light
on how the brain resolves local informational ambiguities through the use of properly designed nonlinear feedback spiking
networks which run as fast as they can, given the amount of uncertainty in the data that they process. 相似文献
993.
It was investigated whether quorum sensing (QS) mediated by N-acylhomoserine lactones (AHLs) was important for heterotrophic bacteria from the littoral zone of the oligotrophic Lake Constance
for growth with organic particles. More than 900 colonies from lake water microcosms with artificial organic aggregates consisting
of autoclaved unicellular algae embedded in agarose beads were screened for AHL-production. AHL-producing bacteria of the
genus Aeromonas enriched in the microcosms but AHLs could not be detected in any microcosm. To test for a potential function of AHL-mediated
QS, growth experiments with the wild type and an AHL-deficient mutant of Aeromonas hydrophila in lake water microcosms were performed. Growth of both strains did not differ in single cultures and showed no mutual influence
in co-cultures. In co-cultures with a competitor bacterium belonging to the Cytophaga–Flavobacterium group, growth of both A. hydrophila strains was reduced while growth of the competitor bacterium was not affected. Exogenous AHL-addition did not influence growth
of the Aeromonas strains in any microcosm experiment. These results showed that AHL-mediated QS was not required for A. hydrophila during colonization and degradation of organic particles in lake water microcosms, suggesting that cell–cell signalling of
heterotrophic bacteria in oligotrophic waters relies on novel signal molecules. 相似文献
994.
Perspectives of microbial oils for biodiesel production 总被引:7,自引:0,他引:7
Biodiesel has become more attractive recently because of its environmental benefits, and the fact that it is made from renewable
resources. Generally speaking, biodiesel is prepared through transesterification of vegetable oils or animal fats with short
chain alcohols. However, the lack of oil feedstocks limits the large-scale development of biodiesel to some extent. Recently,
much attention has been paid to the development of microbial, oils and it has been found that many microorganisms, such as
algae, yeast, bacteria, and fungi, have the ability to accumulate oils under some special cultivation conditions. Compared
to other plant oils, microbial oils have many advantages, such as short life cycle, less labor required, less affection by
venue, season and climate, and easier to scale up. With the rapid expansion of biodiesel, microbial oils might become one
of potential oil feedstocks for biodiesel production in the future, though there are many works associated with microorganisms
producing oils need to be carried out further. This review is covering the related research about different oleaginous microorganisms
producing oils, and the prospects of such microbial oils used for biodiesel production are also discussed. 相似文献
995.
Nicklas Samils Antoni Olivera Eric Danell Susan J. Alexander Christine Fischer Carlos Colinas 《Economic botany》2008,62(3):331-340
The Socioeconomic Impact of Truffle Cultivation in Rural Spain. Commercial black truffle (Tuber melanosporum) plantations have been promoted in Europe with the intention of benefiting rural economies while conserving biodiversity through the expansion of oak woodlands. In this context, a socioeconomic study was conducted around the town of Sarrión in eastern Spain, where government subsidies have supported oak reforestation and truffle cultivation in unproductive hilly areas since 1987. Currently there are about 4,500 ha of truffle orchards in the surrounding county and 530 members in the local truffle association, which has provided a key forum for truffle cultivators to share technical, financial and administrative experiences. Structured interviews were carried out in 2002 with a number of orchard owners, as well as representatives of financial and governmental institutions. Truffles, which are harvested using trained dogs, typically fetch local cultivators average prices of 220–670 EUR/kg, although retail prices of high-quality specimens may reach twice this amount. In addition to the direct economic impact, an increase in local land prices was also documented, as well as a tendency for continued expansion of truffle orchards, and thus oak reforestation. In conclusion, the promotion of truffle cultivation through autonomous community and provincial government subsidies, in conjunction with support by local banks, a dedicated local truffle association, and growing interest on behalf of local farmers, seems to have achieved the mutual goals of biodiversity conservation and improving the rural economy in this region of Spain. 相似文献
996.
Valtcheva-Sarker R Stephanova E Hristova K Altankov G Momchilova A Pankov R 《Molecular and cellular biochemistry》2007,295(1-2):59-64
Halothane is a volatile anaesthetic, which is known to induce alterations in cellular plasma membranes, modulating the physical
state of the membrane lipids and/or interacting directly with membrane-bound proteins, such as integrin receptors. Integrin-mediated
cell adhesion is a general property of eukaryotic cells, which is closely related to cell viability. Our previous investigations
showed that halothane is toxic for A 549 lung carcinoma cells when applied at physiologically relevant concentrations and
causes inhibition of adhesion to collagen IV.
The present study is focused on the mechanisms underlying halothane toxicity. Our results imply that physiologically relevant
concentrations of halothane disrupt focal adhesion contacts in A 549 cells, which is accompanied with suppression of focal
adhesion kinase activity and paxillin phosphorylation, and not with proteolytic changes or inhibition of vinculin and paxillin
expression.
We suggest that at least one of the toxic effects of halothane is due to a decreased phosphorylation of the focal contact
proteins. 相似文献
997.
Correlations between environmental factors and the distribution of amphibian and reptile species richness were investigated
in a climate transition area, Peneda-Gerês National Park (PNPG), in North-Western Portugal. Using presence-data at a local-scale
(1 × 1 km), Ecological-Niche Factor Analysis (ENFA) identified a mixture of climatic (precipitation and number of days with
fog), topographical (altitude and relief) and habitat factors (number of watercourses and water surfaces, the type of the
largest water surface and tree diversity cover), as accurate predictors of species occurrence. Three factors were common for
both taxonomic groups, and consistently presented a positive relation with species occurrence: precipitation, number of water
surfaces, and tree diversity cover; suggesting a strong coincidence in the environmental correlates that influence amphibian
and reptile species richness. Distribution patterns of observed and predicted species richness were compared using a Geographical
Information System. Overall, three high species richness areas were predicted in common for both taxonomic groups and two
additional areas for amphibians only. These areas matched with the observed species richness but suggested larger areas of
high species richness. The location of the PNPG in a biogeographic crossroad, between Euro-Siberian and Mediterranean provinces,
emphasised species richness of amphibians and reptiles and suggests a high priority conservation status for this protected
area. Most of Central-Northern Portugal is located in a climatic transition area; therefore, increased species richness should
be expected for other areas. Local scale studies for other protected areas should be planned as a framework for the development
of multi-scale conservation planning by Portuguese authorities. 相似文献
998.
Tan-Trung Nguyen Noelya Planchard Jennifer Dahan Nadge Arnal Sandrine Balzergue Abdelilah Benamar Pierre Bertin Vronique Brunaud Cline Dargel-Graffin David Macherel Marie-Laure Martin-Magniette Martine Quadrado Olivier Namy Hakim Mireau 《Molecular biology and evolution》2021,38(8):3445
The high mutational load of mitochondrial genomes combined with their uniparental inheritance and high polyploidy favors the maintenance of deleterious mutations within populations. How cells compose and adapt to the accumulation of disadvantageous mitochondrial alleles remains unclear. Most harmful changes are likely corrected by purifying selection, however, the intimate collaboration between mitochondria- and nuclear-encoded gene products offers theoretical potential for compensatory adaptive changes. In plants, cytoplasmic male sterilities are known examples of nucleo-mitochondrial coadaptation situations in which nuclear-encoded restorer of fertility (Rf) genes evolve to counteract the effect of mitochondria-encoded cytoplasmic male sterility (CMS) genes and restore fertility. Most cloned Rfs belong to a small monophyletic group, comprising 26 pentatricopeptide repeat genes in Arabidopsis, called Rf-like (RFL). In this analysis, we explored the functional diversity of RFL genes in Arabidopsis and found that the RFL8 gene is not related to CMS suppression but essential for plant embryo development. In vitro-rescued rfl8 plantlets are deficient in the production of the mitochondrial heme–lyase complex. A complete ensemble of molecular and genetic analyses allowed us to demonstrate that the RFL8 gene has been selected to permit the translation of the mitochondrial ccmFN2 gene encoding a heme–lyase complex subunit which derives from the split of the ccmFN gene, specifically in Brassicaceae plants. This study represents thus a clear case of nuclear compensation to a lineage-specific mitochondrial genomic rearrangement in plants and demonstrates that RFL genes can be selected in response to other mitochondrial deviancies than CMS suppression. 相似文献
999.
With yeast two-hybrid methods, we used a C-terminal fragment (residues 1697–2145) of non-erythroid beta spectrin (βII-C),
including the region involved in the association with alpha spectrin to form tetramers, as the bait to screen a human brain
cDNA library to identify proteins interacting with βII-C. We applied stringent selection steps to eliminate false positives
and identified 17 proteins that interacted with βII-C (IPβII-C s). The proteins include a fragment (residues 38–284) of “THAP domain containing, apoptosis associated protein 3, isoform
CRA g”, “glioma tumor suppressor candidate region gene 2” (residues 1-478), a fragment (residues 74–442) of septin 8 isoform
c, a fragment (residues 704–953) of “coatomer protein complex, subunit beta 1, a fragment (residues 146–614) of zinc-finger
protein 251, and a fragment (residues 284–435) of syntaxin binding protein 1. We used yeast three-hybrid system to determine
the effects of these βII-C interacting proteins as well as of 7 proteins previously identified to interact with the tetramerization
region of non-erythroid alpha spectrin (IPαII-N s) [1] on spectrin tetramer formation. The results showed that 3 IPβII-C s were able to bind βII-C even in the presence of αII-N, and 4 IPαII-N s were able to bind αII-N in the presence of βII-C. We also found that the syntaxin binding protein 1 fragment abolished
αII-N and βII-C interaction, suggesting that this protein may inhibit or regulate non-erythroid spectrin tetramer formation. 相似文献
1000.
Qaisara Pasha Salman A. Malik Nazia Shaheen Munir H. Shah 《Biological trace element research》2010,134(2):160-173
Trace elements including Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sb, Sr, and Zn were analyzed in the scalp hair
samples of women with malignant breast lesions, women with benign breast lesions, and healthy donors using atomic absorption
spectrophotometric method. In the scalp hair of malignant-tumor patients, the highest average concentration was shown by Ca
(1,187 μg/g), followed by Na (655 μg/g), Mg (478 μg/g), Zn (391 μg/g), Sr (152 μg/g), Fe (114 μg/g), and K (89.8), while in
the case of benign-tumor patients, the average estimated element levels were 1,522, 1,093, 572, 457, 217, 80.4, and 74.7 μg/g,
respectively. Most of the elements exhibited non-normal distribution evidenced by large spread, standard error, and skewness
values. Mean concentrations of Ca (634 μg/g), Zn (206 μg/g), Mg (162 μg/g), Fe (129 μg/g), and Na (82.1 μg/g) were noteworthy
in the scalp hair of healthy women. Average levels of Na, Sr, K, Cd, Co, Pb, Mg, Ca, Zn, Ni, Sb, and Mn were revealed to be
significantly higher in the hair of malignant and benign patients compared to the healthy women; however, Fe, Cu, Al, and
Cr were not significantly different in the scalp hair of the three groups. The quartile distributions of Ca, Cd, Co, Cr, K,
Mg, Mn, Na, Ni, Pb, Sb, and Sr revealed maximum spread in the scalp hair of malignant and benign groups; nevertheless, Al,
Cu, Fe, and Zn exhibited almost comparable quartile levels in the three groups. Strong correlation coefficients were found
between Fe and Cd, Al and Na, Mn and Sr, Co and Cr, Cd and Cr, Pb and K, Pb and Mn, Cu and Na, and Al and Fe in the scalp
hair of malignant-tumor patients, while Fe and K, Cd and Co, Na and Co, and Cr and Pb showed strong correlations in the scalp
hair of benign-tumor patients, both of which were significantly different compared with the healthy subjects. Multivariate
cluster analysis also revealed divergent clustering of the elements in the scalp hair of malignant and benign patients in
comparison with the healthy women. 相似文献