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991.
The rearing environment of first-feeding turbot larvae, usually with high larvae densities and organic matter concentrations, may promote the growth of opportunistic pathogenic Vibrionaceae bacteria, compromising the survival of the larvae. The aim of this study was to assess the effectiveness of the biofilm-forming probiotic Phaeobacter 27-4 strain grown on a ceramic biofilter (probiofilter) in preventing Vibrio anguillarum infections in turbot larvae. In seawater with added microalgae and maintained under turbot larvae rearing conditions, the probiofilter reduced the total Vibrionaceae count and the concentration of V. anguillarum, which was undetectable after 144 h by real-time PCR. The probiofilter also improved the survival of larvae challenged with V. anguillarum, showing an accumulated mortality similar to that of uninfected larvae (35–40 %) and significantly (p?<?0.05) lower than that of infected larvae with no probiofilter (76 %) due to a decrease in the pathogen concentration and in total Vibrionaceae. Furthermore, the probiofilter improved seawater quality by decreasing turbidity. Phaeobacter 27-4 released from the probiofilters was able to survive in the seawater for at least 11 days. The bacterial diversity in the larvae, analysed by denaturing gradient gel electrophoresis, was low, as in the live prey (rotifers), and remained unchanged in the presence of V. anguillarum or the probiofilter; however, the probiofilter reduced the bacterial carrying capacity of the seawater in the tanks. Phaeobacter-grown biofilters can constantly inoculate probiotics into rearing tanks and are therefore potentially useful for bacterial control in both open and recirculating industrial units. 相似文献
992.
Vázquez-Fernández MÁ Bermejo MR Fernández-García MI González-Riopedre G Rodríguez-Doutón MJ Maneiro M 《Journal of inorganic biochemistry》2011,105(12):1538-1547
The peroxidase and catalase activities of eighteen manganese-Schiff base complexes have been studied. A correlation between the structure of the complexes and their catalytic activity is discussed on the basis of the variety of systems studied. Complexes 1-18 have the general formulae [MnLn(D)2](X)(H2O/CH3OH)m, where Ln = L1-L13; D = H2O, CH3OH or Cl; m = 0-2.5 and X = NO3−, Cl−, ClO4−, CH3COO−, C2H5COO− or C5H11COO−. The dianionic tetradentate Schiff base ligands H2Ln are the result of the condensation of different substituted (OMe-, OEt-, Br-, Cl-) hydroxybenzaldehyde with diverse diamines (1,2-diaminoethane for H2L1-H2L2; 1,2-diamino-2-methylethane for H2L3-H2L4; 1,2-diamino-2,2-dimethylethane for H2L5; 1,2-diphenylenediamine for H2L6-H2L7; 1,3-diaminopropane for H2L8-H2L11; 1,3-diamino-2,2-dimethylpropane for H2L12-H2L13). The new Mn(III) complexes [MnL1(H2O)Cl](H2O)2.5 (2), [MnL2(H2O)2](NO3)(H2O) (4), [MnL6(H2O)2][MnL6(CH3OH)(H2O)](NO3)2(CH3OH) (8), [MnL6(H2O)(OAc)](H2O) (9) and [MnL7(H2O)2](NO3)(CH3OH)2 (12) were isolated and characterised by elemental analysis, magnetic susceptibility and conductivity measurements, redox studies, ESI spectrometry and UV, IR, paramagnetic 1H NMR, and EPR spectroscopies. X-ray crystallographic studies of these complexes and of the ligand H2L6 are also reported. The crystal structures of the rest of the complexes have been previously published and herein we have only revised their study by those techniques still not reported (EPR and 1H NMR for some of these compounds) and which help to establish their structures in solution. Complexes 1-12 behave as more efficient mimics of peroxidase or catalase in contrast with 13-18. The analysis between the catalytic activity and the structure of the compounds emphasises the significance of the existence of a vacant or a labile position in the coordination sphere of the catalyst. 相似文献
993.
994.
995.
Alberto Zambrano Verónica García-Carpizo María Esther Gallardo Raquel Villamuera Maria Ana Gómez-Ferrería Angel Pascual Nicolas Buisine Laurent M. Sachs Rafael Garesse Ana Aranda 《The Journal of cell biology》2014,204(1):129-146
There is increasing evidence that the thyroid hormone (TH) receptors (THRs) can play a role in aging, cancer and degenerative diseases. In this paper, we demonstrate that binding of TH T3 (triiodothyronine) to THRB induces senescence and deoxyribonucleic acid (DNA) damage in cultured cells and in tissues of young hyperthyroid mice. T3 induces a rapid activation of ATM (ataxia telangiectasia mutated)/PRKAA (adenosine monophosphate–activated protein kinase) signal transduction and recruitment of the NRF1 (nuclear respiratory factor 1) and THRB to the promoters of genes with a key role on mitochondrial respiration. Increased respiration leads to production of mitochondrial reactive oxygen species, which in turn causes oxidative stress and DNA double-strand breaks and triggers a DNA damage response that ultimately leads to premature senescence of susceptible cells. Our findings provide a mechanism for integrating metabolic effects of THs with the tumor suppressor activity of THRB, the effect of thyroidal status on longevity, and the occurrence of tissue damage in hyperthyroidism. 相似文献
996.
We report the aerobic biodegradation of Microcystin-RR (MC-RR) by a bacterial strain isolated from San Roque reservoir (Córdoba – Argentina). This bacterium was identified as Sphingomonas sp. (CBA4) on the basis of 16S rDNA sequencing. The isolated strain was capable of degrading completely MC-RR (200 μg l−1) within 36 h. We have found evidence that MC-RR biodegradation pathway by this Sphingomonas sp. strain would start by demethylating MC-RR, affording an intermediate product, which is finally biodegraded by this strain within 72 h. Our results confirm that certain environmental bacteria, living in the same habitat as toxic cyanobacteria, have the capability to perform complete biodegradation of MC, leading to natural bioremediation of waterbodies. The bacterium reported here presents genetic homologies with other strains that degrade MC-LR. However, initial demethylation of MC-RR has been not described previously, raising questions on the probable presence of different biodegradation pathways for different MC variants. 相似文献
997.
Balcão VM Mateo C Fernández-Lafuente R Malcata FX Guisán JM 《Biotechnology progress》2001,17(3):537-542
A new protocol for the stabilization of the quaternary structure of multimeric enzymes has been attempted using as model enzyme (tetrameric) L-asparaginase from Escherichia coli. Such strategy is based upon multisubunit covalent immobilization of the enzyme onto activated supports (agarose-glutaraldehyde). Supports activated with different densities of reactive groups were used; the higher the density of groups, the higher the stabilization attained. However, because of the complexity of that enzyme, even the use of the highest densities of reactive groups was not enough to encompass all four subunits in the immobilization process. Therefore, a further chemical intersubunit cross-linking with aldehyde-dextran was pursued; these derivatives displayed a fully stabilized multimeric structure. In fact, boiling the modified enzyme derivative in the presence of sodium dodecyl sulfate and beta-mercaptoethanol did not lead to release of any enzyme subunit into the medium. Such a derivative, prepared under optimal conditions, retained ca. 40% of the intrinsic activity of the free enzyme and was also functionally stabilized, with thermostabilization enhancements of ca. 3 orders of magnitude when compared with its soluble counterpart. This type of derivative may be appropriate for extracorporeal devices in the clinical treatment of acute leukemia and might thus bring about inherent advantages in that all subunits are covalently bound to the support, with a longer half-life and a virtually nil risk of subunit release into the circulating blood stream. 相似文献
998.
Echevarría-Machado I Martínez-Estévez M Muñoz-Sánchez JA Loyola-Vargas VM Hernández-Sotomayor SM De Los Santos-Briones C 《Molecular biotechnology》2007,35(3):297-309
We have previously reported that Catharanthus roseus transformed roots contain at least two phosphatidylinositol 4,5-bisphosphate-phospholipase C (PLC) activities, one soluble
and the other membrane associated. Detergent, divalent cations, and neomycin differentially regulate these activities and
pure protein is required for a greater understanding of the function and regulation of this enzyme. In this article we report
a partia purification of membrane-associated PLC. We found that there are at least two forms of membrane-associated PLC in
transformed roots of C. roseus. These forms were separated on the basis of their affinity for heparin. One form shows an affinity for heparin and elutes
at approx 600 mM KCl. This form has a molecular mass of 67 kDa by size exclusion chromatography and Western blot analysis, whereas the other
form does not bind to heparin and has a molecular mass of 57 kDa. Possible differential regulation of these forms during transformed
root growth is discussed. 相似文献
999.
Wheat plants were grown from sowing to day 18 in 26-dm3 chambers at three different CO2 concentrations: 150 (-CO2), 350 (C, control), 800 (+CO2) mol mol-1. Afterwards, plants of the three variants were grown at the same natural CO2 concentration. Plant characteristics were measured just before the transfer (0 days after CO2 treatment, DAT), and at 5 – 8 DAT on the 1st leaf, and at 12 – 22 DAT on the 4th leaf. Decreased or increased CO2 concentrations caused acclimations which persisted after transplantation to natural CO2 concentration. At 5 – 8 DAT, stomatal density, stomatal conductance (gs), CO2 saturated net photosynthetic rate (PNsat0), radiation saturated net photosynthetic rate (PNsat1), and carboxylation efficiency () were higher in -CO2 plants and lower in +CO2 plants than in C plants. As compared with C plants, the photochemical efficiency () was lower in -CO2 and higher in -CO2 plants, however, chlorophyll (Chl) a, Chl b, Chl a–b and carotenoid contents were lower in both -CO2 and +CO2 plants. On the 4th leaf, which emerged on plant after finishing CO2 treatments, at 12 – 22 DAT, no differences in stomatal density and g, between treatments were observed. In -CO2 plants, pigment content and PNsat0 were higher, was lower, and PNsat1 and were not different from C plants. In contrast, in +CO2 plants, pigment content, PNsat1 and were lower, and PNsat0 and were unchanged. Leaf area, dry mass, and tiller development increased in +CO2 plants and decreased in -CO2 plants. In the interval between 8 and 22 DAT, lower net assimilation rate in +CO2 than in -CO2 plants was observed. 相似文献
1000.
Understanding how plant–animal interactions shape plant regeneration is traditionally examined at local scales. In contrast, landscape ecologists working at regional scales often have to infer the mechanisms underlying vegetation patterns. In this study, we empirically explored how landscape attributes (patch connectivity, size, shape, irradiance, slope, and elevation) influence biotic interactions in 1- and 2-year seedlings and saplings of Quercus ilex. We combined field data and GIS-based information under a set of five connectivity scenarios, presuming low, intermediate, and long-distance seed dispersal. Our study emphasizes that landscape, apart from its direct effects on plants, plays a key, albeit indirect, role in plant demography through its effects on seed dispersers and predators. Moreover, the effects of landscape on recruitment differed between plant life stages. One-year seedlings and saplings appear to depend more on plant–animal interactions, while 2-year seedlings depend more on irradiance. Differences in patch connectivity resulted in direct and indirect effects on biotic interactions, which, in turn, produced contrasting positive and negative effects on regeneration at different stages of the life cycle. While jays and wild boars seem crucial to all life stages and most of the connectivity scenarios, rodents and herbivores affected only 1-year seedlings and saplings, respectively, and only a few of the connectivity scenarios. By simultaneously including an ensemble of explanatory factors, our study emphasizes that regeneration depends on a set of key drivers, both abiotic (i.e. irradiance) and biotic (i.e. jays and wild boars), whose effects are greatly modulated by landscape traits. 相似文献