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排序方式: 共有944条查询结果,搜索用时 15 毫秒
1.
D.A.M. da Silva M.S. Fernandes E.H. Endo A.C.P. Vital E.A. Britta M.E. Favero J.C. Castro P.T. Matumoto-Pintro B.P. Dias Filho C.V. Nakamura M. Machinski Junior J.M.G. Mikcha B.A. de Abreu Filho 《Letters in applied microbiology》2021,72(1):41-52
The use of rosemary essential oil (RO) and its combination with nisin (RO+N) in preventing the multiplication of Alicyclobacillus acidoterrestris in orange juice was evaluated. The minimum inhibitory and bactericidal concentrations (MIC and MBC) for RO were both 125 μg ml−1 while RO+N displayed a synergistic effect. The use of RO and RO+N at concentrations of 1, 4 and 8× MIC in orange juice for 96 h was evaluated in terms of their sporicidal effectiveness. With regard to the action against A. acidoterrestris spores, RO at 8× MIC was sporostatic, whereas RO+N at 1× MIC was sporicidal. Morphological changes in the structure of the micro-organism after treatment were also observed by microscopy. Furthermore, flow cytometric analysis showed that most cells were damaged or killed after treatment. In general, the antioxidant activity after addition of RO+N decreased with time. The results demonstrate that using the combination of RO and nisin can prevent the A. acidoterrestris growth in orange juice. 相似文献
2.
Upregulation of small heat-shock proteins (sHsps) in response to cellular stress is one mechanism to increase cell viability. We previously described that cultured rat hippocampal neurons express five of the 11 family members but only upregulate two of them (HspB1 and HspB5) at the protein level after heat stress. Since neurons have to cope with many other pathological conditions, we investigated in this study the expression of all five expressed sHsps on mRNA and protein level after sublethal sodium arsenite and oxidative and hyperosmotic stress. Under all three conditions, HspB1, HspB5, HspB6, and HspB8 but not HspB11 were consistently upregulated but showed differences in the time course of upregulation. The increase of sHsps always occurred earlier on mRNA level compared with protein levels. We conclude from our data that these four upregulated sHsps (HspB1, HspB5, HspB6, HspB8) act together in different proportions in the protection of neurons from various stress conditions. 相似文献
3.
Phosphorylation of Thylakoid Proteins of Oryza sativa: In Vitro Characterization and Effects of Chilling Temperatures
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The phosphorylation of thylakoid proteins of rice (Oryza sativa L.) was studied in vitro using [γ-32P]ATP. Several thylakoid proteins are labeled, including the light-harvesting complex of photosystem II. Protein phosphorylation is sensitive to temperature, pH, and ADP, ATP, and divalent cation concentrations. In the range pH 7 to 8.2, phosphorylation of the light-harvesting polypeptides declines above pH 7.5, whereas labeling of several other thylakoid polypeptides increases. Increasing divalent cation concentration from 3 to 20 millimolar results in a decrease in phosphorylation of the 26 kilodalton light-harvesting complex polypeptide and increased phosphorylation of several other polypeptides. ADP has an inhibitory effect on the phosphorylation of the light-harvesting complex polypeptides. Phosphorylation of the 26 kilodalton light-harvesting polypeptide requires 0.45 millimolar ATP for half-maximal phosphorylation, compared to 0.3 millimolar for the 32 kilodalton phosphoprotein. Low temperature inhibits the phosphorylation of thylakoid proteins in chilling-sensitive rice. However, phosphorylation of histones by thylakoid-bound kinase(s) is independent of temperature in the range of 25 to 5°C, suggesting that the effect of low temperature is on accessibility of the substrate, rather than on the activity of the kinase. 相似文献
4.
Taxonomic identification of Streptomyces exfoliatus K10 and characterization of its poly(3-hydroxybutyrate) depolymerase gene 总被引:1,自引:0,他引:1
Britta Klingbeil Reiner M. Kroppenstedt Dieter Jendrossek 《FEMS microbiology letters》1996,142(2-3):215-221
Abstract Using fungi grown on synthetic agar medium, we evaluated and compared the concentration of various H2 O2 -producing enzymes. Our results showed that oxidase production in solid medium was better than that found in liquid medium and as high as that detected in wood samples. High yields of oxidases made it possible to compare different oxidases in the same culture extracts and under different conditions. Our results also indicated that H2 O2 production is ubiquitous in the white rot fungi tested and that enzyme levels are influenced by the substrate composition. 相似文献
5.
Concentrations of Amino Acids in Extracellular Fluid After Opening of the Blood-Brain Barrier by Intracarotid Infusion of Protamine Sulfate 总被引:3,自引:0,他引:3
Irena Westergren Britta Nystrom ers Hamberger Claes Nordborg Barbro B. Johansson 《Journal of neurochemistry》1994,62(1):159-165
Abstract: This article evaluates the influence of an opening of the blood-brain barrier (BBB) on compounds in brain extracellular fluid. The concentrations of amino acids and some other primary amines were determined in dialysates sampled from the right parietal cortex of rats before and after an intracarotid infusion of protamine sulfate. Extravasated plasma proteins were visualized by Evans blue/albumin and immunohistochemistry. CSF albumin— an indicator of blood-CSF barrier opening—was quantified with immunoelectrophoresis. The brains were macroscopically edematous after 10 mg but not after 5 mg of protamine sulfate. The higher dose led to a 50% death rate. The concentrations of amino acids did not change 10 min after the BBB opening. No significant alterations in the amino acid concentrations were observed after the lower dose. The concentrations of glutamate, aspartate, GABA, glycine, taurine, and phosphoethanolamine increased significantly within 50–80 min after the infusion of 10 mg of protamine sulfate. CSF albumin levels were significantly increased 1 h after infusion. We conclude that a dysfunction of the BBB, of a degree known to induce brain edema (10 mg of protamine sulfate), significantly increases the extracellular concentration of excitatory amino acids, GABA, taurine, and phosphoethanolamine in the extracellular space. 相似文献
6.
Augusto C. Franco Angela Haag-Kerwer Britta Herzog Thorsten E. E. Grams Erika Ball Eduardo A. de Mattos Fabio R. Scarano Suzanne Barreto Maria A. Garcia Andre Mantovani Ulrich Lüttge 《Trees - Structure and Function》1996,10(6):359-365
Sandy plains are characteristic of the coastal region of Brazil. We investigated the diel patterns of changes in organic acid levels, leaf conductance and chlorophylla fluorescence for sun-exposed and shaded plants ofClusia hilariana, one of the dominant woody species in the sandy coastal plains of northern Rio de Janeiro state. Both exposed and shaded plants showed a typical CAM pattern with considerable diel oscillations in organic acid levels. The degradation of both malic and citric acids during the midday stomatal closure period could lead to potential CO2 fixation rates of 28 mol m-2 s-1 in exposed leaves. Moreover, exposed leaves exhibited large increases in total non-photochemical quenching (qN) accompanied by a substantial decrease in effective quantum yield during the course of the day. However, these potential high rates of CO2 fixation and the increases inqn of exposed plants were not enough to maintain the primary electron acceptor of photosystem II (qA) in a low reduction state, similar to that of shaded plants. As a result, there was a moderate increase in the reduction state of qA throughout the day. Most of the decline in photochemical efficiency of exposed leaves ofC. hilariana was reversible, as evidenced by the high levels of pre-dawn potential quantum yields (Fv/Fm) and their rapid recovery after sunset. However, the depletion of the organic acid pool in the afternoon resulted in an accentuated subsequent drop in Fv/Fm, suggesting that prolonged periods of water stress accompanied by high irradiance levels may expose plants ofC. hilariana in unprotected habitats to the danger of photoinhibition. 相似文献
7.
Britta Swebilius Singer Larry Gold Sidney T. Shinedling Michelle Colkitt Lawrence R. Hunter David Pribnow Mary Anne Nelson 《Journal of molecular biology》1981,149(3):405-432
We have mapped the mutants isolated by Nelson et al. (1981) that reduce the amount of rIIB protein synthesized during bacteriophage T4 infection of Escherichia coli B and characterized their rIIB expression in vivo. These mutants fall into four distinct groups in terms of mapping and phenotype. We have located the probable site of each mutation on the DNA sequence. We have also analyzed a number of other mutations near the initiating AUG of rIIB with respect to their rIIB expression. In some of these mutants, ribosomal recognition of the wild-type initiating AUG is precluded and so initiation occurs at a different AUG, which, in some instances, we have identified. 相似文献
8.
The regeneration of surface anionic groups in mouse peritoneal macrophages was investigated by electron microscopy, using cationized ferritin (CF) as a tool for the localization and evaluation of negative charge density on the cell surface. In vitro interaction of living macrophages with CF resulted in removal of most anionic groups, either by concentration of their receptor sites to a part of the membrane which is subsequently internalized, or by detachment of the aggregated label from the surface. After incubation of macrophages lacking surface anionic groups in tissue culture medium without the ligand, regeneration of the binding capacity for CF took place within 3 h. The first regenerated parts of the membrane can be visualized within 1 h on the upper part of the adherent cells; there is a discontinuous coating of ferritin, with the lateral regions of the plasmalemma free of label. The attached CF particles on the regenerated membrane are closer to the membrane and their density is considerably higher than on the normal control macrophages. The results indicate that the turnover of the plasmalemma is regional and not dispersed; the mechanism involved is insertion of membrane patches into the pre-existing plasma membrane. 相似文献
9.
Biocontrol of Listeria monocytogenes on Fresh-Cut Produce by Treatment with Lytic Bacteriophages and a Bacteriocin
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Britta Leverentz William S. Conway Mary J. Camp Wojciech J. Janisiewicz Tamuna Abuladze Ming Yang Robert Saftner Alexander Sulakvelidze 《Applied microbiology》2003,69(8):4519-4526
The fresh-cut produce industry has been the fastest-growing portion of the food retail market during the past 10 years, providing consumers with convenient and nutritious food. However, fresh-cut fruits and vegetables raise food safety concerns, because exposed tissue may be colonized more easily by pathogenic bacteria than intact produce. This is due to the higher availability of nutrients on cut surfaces and the greater potential for contamination because of the increased amount of handling. We found that applied Listeria monocytogenes populations survived and increased only slightly on fresh-cut Red Delicious apples stored at 10°C but increased significantly on fresh-cut honeydew melons stored at 10°C over 7 days. In addition, we examined the effect of lytic, L. monocytogenes-specific phages via two phage application methods, spraying and pipetting, on L. monocytogenes populations in artificially contaminated fresh-cut melons and apples. The phage mixture reduced L. monocytogenes populations by 2.0 to 4.6 log units over the control on honeydew melons. On apples, the reduction was below 0.4 log units. In combination with nisin (a bacteriocin), the phage mixture reduced L. monocytogenes populations by up to 5.7 log units on honeydew melon slices and by up to 2.3 log units on apple slices compared to the control. Nisin alone reduced L. monocytogenes populations by up to 3.2 log units on honeydew melon slices and by up to 2.0 log units on apple slices compared to the control. The phage titer was stable on melon slices, but declined rapidly on apple slices. The spray application of the phage and phage plus nisin reduced the bacterial numbers at least as much as the pipette application. The effectiveness of the phage treatment also depended on the initial concentration of L. monocytogenes. 相似文献
10.
Bernd Wissinger Herbert Jägle Susanne Kohl Martina Broghammer Britta Baumann David B Hanna Christian Hedels Eckhard Apfelstedt-Sylla Giorgio Randazzo Samuel G Jacobson Eberhart Zrenner Lindsay T Sharpe 《Genomics》1998,51(3):325
We have performed linkage analysis in eight families with rod monochromacy, an autosomal recessively inherited condition with complete color blindness. Significant linkage was found with markers located at the pericentromeric region of chromosome 2. A maximum lod score of 5.36 was obtained for marker D2S2333 at θ = 0.00. Mapping of meiotic breakpoints localized the disease gene between markers D2S2187 and D2S2229. Homozygosity for a number of subsequent markers indicating identity by descent was found in two families and provides evidence for a further refinement of the locus proximal to D2S373. This defines an interval of ≈3 cM covering theACHM2locus for rod monochromacy. Radiation hybrid mapping of theCNGA3gene encoding the α-subunit of the cGMP gated cation channel in human cone photoreceptors resulted in a maximum lod score of 16.1 with marker D2S2311 combined with a calculated physical distance of 6.19cR10,000. Screening of the CEPH YAC library and subsequent STS mapping indicated the physical order cen–D2S2222–D2S2175–(D2S2187/D2S2311)–qtel ofmarkers on 2q11 and showed that theCNGA3gene maps most closely to D2S2187 and D2S2311. These data indicate that theCNGA3gene maps within the critical interval of theACHM2locus for rod monochromacy and thus is a candidate gene for this disease. 相似文献