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151.
152.
153.
Taíse F. Pedroso Cláudia S. Oliveira Mariana M. Fonseca Vitor A. Oliveira Maria Ester Pereira 《Biological trace element research》2017,180(2):275-284
This study investigated the toxicity of rats exposed to lead acetate (AcPb) during the second phase of brain development (8–12 days postnatal) in hematological and cerebral parameters. Moreover, the preventive effect of zinc chloride (ZnCl2) and N-acetylcysteine (NAC) was investigated. Pups were injected subcutaneously with saline (0.9% NaCl solution), ZnCl2 (27 mg/kg/day), NAC (5 mg/kg/day) or ZnCl2 plus NAC for 5 days (3rd–7th postnatal days), and with saline (0.9% NaCl solution) or AcPb (7 mg/kg/day) in the five subsequent days (8th–12th postnatal days). Animals were sacrificed 21 days after the last AcPb exposure. Pups exposed to AcPb presented inhibition of blood porphobilinogen-synthase (PBG-synthase) activity without changes in hemoglobin content. ZnCl2 pre-exposure partially prevented PBG-synthase inhibition. Regarding neurotoxicity biomarkers, animals exposed to AcPb presented a decrease in cerebrum acetylcholinesterase (AChE) activity and an increase in Pb accumulation in blood and cerebrum. These changes were prevented by pre-treatment with ZnCl2, NAC, and ZnCl2 plus NAC. AcPb exposure caused no alteration in behavioral tasks. In short, results show that AcPb inhibited the activity of two important enzymatic biomarkers up to 21 days after the end of the exposure. Moreover, ZnCl2 and NAC prevented the alterations induced by AcPb. 相似文献
154.
David R Arahal Ester Sánchez M Carmen Macián Esperanza Garay 《International microbiology》2008,11(1):33-39
The genera Leuconostoc, Oenococcus, and Weissella (family "Leuconostocaceae") constitute a group of lactic acid bacteria of great interest in food microbiology. From the taxonomic point of view, they are considered phylogenetically coherent according to their 16S rRNA gene sequences and other macromolecules. These three genera were the focus of the present study; specifically, the resolution and discriminatory power of recN (encoding a DNA repair and genetic recombination protein) as a molecular marker at the species level were investigated. For this purpose, partial sequences (about 1200 nt) were obtained from 23 type strains and from several additional strains following direct amplification of recN and subsequent sequencing. Phylogeny was evaluated according to different treeing methods (neighbor joining, maximum likelihood, and maximum parsimony) and the inclusion of variability filters. The results showed that recN, used either alone or in combination with 16S rRNA data, can serve as a phylogenetic marker as well as a tool for species identification. 相似文献
155.
Maria Carmen Collado Ester Donat Carmen Ribes-Koninckx Miguel Calabuig Yolanda Sanz 《BMC microbiology》2008,8(1):232
Background
Gut bifidobacteria are believed to influence immune-related diseases. The objective of this study was to assess the possible relationships between the gut bifidobacteria composition and coeliac disease (CD) in children. 相似文献156.
Biasutto L Mattarei A Marotta E Bradaschia A Sassi N Garbisa S Zoratti M Paradisi C 《Bioorganic & medicinal chemistry letters》2008,18(20):5594-5597
To target natural polyphenols to the subcellular site where their redox properties might be exploited at best, that is, mitochondria, we have synthesised new proof-of-principle derivatives by linking resveratrol (3,4',5-trihydroxy-trans-stilbene) to the membrane-permeable lipophilic triphenylphosphonium cation. The new compounds, (4-triphenylphosphoniumbutyl)-4'-O-resveratrol iodide and its bis-acetylated derivative, the latter intended to provide transient protection against metabolic conjugation, accumulate into energized mitochondria as expected and are cytotoxic for fast-growing but not for slower-growing cells. They provide a powerful potential tool to intervene on mitochondrial and cellular redox processes of pathophysiological relevance. 相似文献
157.
Silva FV Goulart M Justino J Neves A Santos F Caio J Lucas S Newton A Sacoto D Barbosa E Santos MS Rauter AP 《Bioorganic & medicinal chemistry》2008,16(7):4083-4092
Octyl and dodecyl glycosides possessing 2-deoxy-arabino-hexopyranoside moieties belonging to the D- and L-series in their alpha- and beta-forms were synthesized by reaction of an acetyl protected glycal with octanol or dodecanol, catalyzed by triphenylphosphine hydrobromide, followed by deprotection. Their surface properties were studied and discussed in terms of the adsorption and aggregation parameters, pC(20), CMC, and gamma(CMC). The antimicrobial activities were assessed using the paper disk diffusion and broth dilution methods. Both the octyl and dodecyl 2-deoxy beta-D-glycosides inhibited significantly Enterococcus faecalis, a microbe also highly susceptible to dodecyl 2,6-dideoxy-alpha-L-arabino-hexopyranoside. This compound was particularly active against Bacillus cereus and Bacillus subtilis, presenting for both Bacillus species a minimal inhibitory concentration of the same order of magnitude and a minimal lethal concentration even smaller than that obtained for chloramphenicol, a bioactivity which remained unaltered after 1 year solution storage at 4 degrees C. In addition, activity over Listeria monocytogenes was also observed. Direct cytotoxicity and genotoxicity of the glycosides were determined by proliferative index (mitotic index) evaluation in peripheral human lymphocytes of healthy donors. All compounds induced acute toxicity effects, and the response was dose dependent for the alpha-anomer of both the alkyl 2-deoxy-arabino-hexopyranosides and for the corresponding dodecyl beta-anomer, what suggests that non-toxic but still bioactive concentrations may be found for these compounds. 相似文献
158.
Cry1A toxins produced by Bacillus thuringiensis bind a cadherin receptor that mediates toxicity in different lepidopteran insect larvae. Insect cadherin receptors are modular proteins composed of three domains, the ectodomain formed by 9-12 cadherin repeats (CR), the transmembrane domain and the intracellular domain. Cry1A toxins interact with three regions of the Manduca sexta cadherin receptor that are located in CR7, CR11 and CR12 cadherin repeats. Binding of Cry1A toxin to cadherin induces oligomerization of the toxin, which is essential for membrane insertion. Also, it has been reported that cadherin fragments containing the CR12 region enhanced the insecticidal activity of Cry1Ab toxin to M. sexta and other lepidopteran larvae. Here we report that cadherin fragments corresponding to CR7 and CR11 regions also enhanced the activity of Cry1Ac and Cry1Ab toxin to M. sexta larvae, although not as efficient as the CR12 fragment. A single point mutation in the CR12 region (I1422R) affected Cry1Ac and Cry1Ab binding to the cadherin fragments and did not enhance the activity of Cry1Ab or Cry1Ac toxin in bioassays. Analysis of Cry1Ab in vitro oligomer formation in the presence of wild type and mutated cadherin fragments showed a correlation between enhancement of Cry1A toxin activity in bioassays and in vitro Cry1Ab-oligomer formation. Our data shows that formation of Cry1A toxin oligomer is in part responsible for the enhancement of Cry1A toxicity by cadherin fragments that is observed in vivo. 相似文献
159.
Jeroen B. Guinée Reinout Heijungs Ester van der Voet 《The International Journal of Life Cycle Assessment》2009,14(4):328-339
Background, aim, and scope The expectations with respect to biomass as a resource for sustainable energy are sky-high. Many industrialized countries
have adopted ambitious policy targets and have introduced financial measures to stimulate the production or use of bioenergy.
Meanwhile, the side-effects and associated risks have been pointed out as well. To be able to make a well-informed decision,
the Dutch government has expressed the intention to include sustainability criteria into relevant policy instruments.
Main features Among other criteria, it has been proposed to calculate a so-called life-cycle-based greenhouse gas (GHG) indicator, which
expresses the reduction of GHG emissions of a bio-based fuel chain in comparison with a fossil-based fuel chain. Life-cycle-based
biofuel studies persistently have problems with the handling of biogenic carbon balances and with the treatment of coproducts
and recycling. In life-cycle assessments (LCAs) of agricultural products, a distinction between “negative” and “positive”
emissions may be relevant. In particular, carbon dioxide, as a naturally occurring compound or an anthropogenic emission,
takes part in the so-called geochemical carbon cycle. The most appropriate way to treat carbon cycles is to view them as genuine
cycles and, thus, at the systems level, subtract the fixation of CO2 during tree growth from the CO2 emitted during waste treatment of discarded wood and to quantify the CH4 emitted. In solving the multifunctionality problem, two steps may be distinguished. The first concerns the modeling of the
product system studied in the inventory analysis. In this step, system boundaries are set, processes are described, and process
flows are quantified. Multifunctionality problems can be identified and the model of the product system is drafted. The second
step concerns solving the remaining multifunctionality problems. For this step, various ways of solving the multifunctionality
problem have been proposed and applied, on the basis of mass, energy, economic value, avoided burdens, etc. As the GHG indicator
may constitute the basis for granting subsidies to stimulate the use of bioenergy, for example, and as the method for the
GHG indicator provides no guidelines on the handling of biogenic CO2 and guidelines for solving multifunctionality problems such as with coproducts and recycling that leave room for various
choices, this study analyzed whether the current GHG indicator provides results that are a robust basis for granting such
subsidies.
Results For the robustness check, a hypothetical case study on wood residue-based electricity was set up in order to illustrate what
the effects of different solutions and choices for the two steps mentioned may be. The case dealt with the production of wood
pellets (residues of the wood industry) that are cofired in a coal-fired power plant. The functional unit is 1 kWh of electricity.
Three possibilities for the places of the multifunctional process, two possibilities for whether or not to include biogenic
CO2, and four possibilities for the allocation method were distinguished and calculated. Varying the options for these three
choices in this way appears to have a huge effect on the GHG indicator, while no clear pattern seems to emerge.
Discussion The results found for this hypothetical case indicate that there are several methodological choices that have not sufficiently
been fixed by the presently available standards and guidelines for LCA and GHG assessment of bioenergy systems. In particular,
we have focused on issues related to biogenic CO2 and allocation, two issues that play a prominent role in the assessment of bioenergy systems. Moreover, we have demonstrated
with a small hypothetical case study that these are not only issues that might theoretically show up, but that they play a
decisive role in practice.
Conclusions The present (Dutch) GHG indicator lacks robustness, which will raise problems for providing a sound basis for granting subsidies.
This situation can, however, be improved by reducing the freedom of choices for the handling of biogenic CO2 and allocation to an absolute minimum.
Recommendations and perspectives Even then, however, differences could appear due to different definitions, data sources, and method interpretations. It thus
appears that two kinds of guidance are needed: (1) the LCA methodology itself should be expanded with guidelines for those
issues that follow from science, logic, or consensus; (2) in the policy regulation that demands LCA to be the basis of the
decision, additional guidelines should be specified that perhaps do not (yet) have the status of being scientifically proven
or generally agreed upon, but that serve as a set of temporary extra guidelines.
相似文献
Jeroen B. GuinéeEmail: |
160.
Sabino Pacheco Isabel G��mez Ivan Arenas Gloria Saab-Rincon Claudia Rodr��guez-Almaz��n Sarjeet S. Gill Alejandra Bravo Mario Sober��n 《The Journal of biological chemistry》2009,284(47):32750-32757
Bacillus thuringiensis Cry toxins are used worldwide as insecticides in agriculture, in forestry, and in the control of disease transmission vectors. In the lepidopteran Manduca sexta, cadherin (Bt-R1) and aminopeptidase-N (APN) function as Cry1A toxin receptors. The interaction with Bt-R1 promotes cleavage of the amino-terminal end, including helix α-1 and formation of prepore oligomer that binds to APN, leading to membrane insertion and pore formation. Loops of domain II of Cry1Ab toxin are involved in receptor interaction. Here we show that Cry1Ab mutants located in domain II loop 3 are affected in binding to both receptors and toxicity against Manduca sexta larvae. Interaction with both receptors depends on the oligomeric state of the toxin. Monomers of loop 3 mutants were affected in binding to APN and to a cadherin fragment corresponding to cadherin repeat 12 but not with a fragment comprising cadherin repeats 7–12. In contrast, the oligomers of loop 3 mutants were affected in binding to both Bt-R1 fragments but not to APN. Toxicity assays showed that either monomeric or oligomeric structures of Cry1Ab loop 3 mutations were severely affected in insecticidal activity. These data suggest that loop 3 is differentially involved in the binding with both receptor molecules, depending on the oligomeric state of the toxin and also that possibly a “ping pong” binding mechanism with both receptors is involved in toxin action. 相似文献