Control of the growth of Alicyclobacillus acidoterrestris in industrialized orange juice using rosemary essential oil and nisin

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.     

Reaction of small heat-shock proteins to different kinds of cellular stress in cultured rat hippocampal neurons

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.     

Cloning and expression of the gene for a fibronectin-binding protein from Staphylococcus aureus.

The gene encoding the fibronectin-binding protein (FNBP) from Staphylococcus aureus strain 8325-4 was isolated from a gene bank in pBR322. The original clone, containing a 6.5-kb insert, gave a functional product present in the periplasm of Escherichia coli. Analysis of polypeptides isolated after affinity chromatography on fibronectin-Sepharose followed by ion-exchange chromatography revealed two gene products, 87 and 165 kd in mol. wt. The amino acid compositions of these two polypeptides and a native FNBP from S. aureus strain Newman were very similar. Antibodies raised against the native FNBP from strain Newman precipitated the 125I-labelled 165-kd polypeptide, and unlabeled 165- and 87-kd polypeptides as well as native FNBP inhibited the immunoprecipitation reactions. The region of the fnbp-gene encoding the fibronectin-binding activity has been identified and subcloned in an expression vector based on the staphylococcal protein A gene. The resulting product in E. coli is an extracellular fusion protein consisting of two IgG-binding domains of protein A followed by a fibronectin-binding region. The fusion protein binds to fibronectin and completely inhibits the binding of fibronectin to intact cells of S. aureus.     

Expression in Bacillus subtilis of the gene for human urogastrone using synthetic ribosome binding sites

Summary A chemically synthesised gene coding for human urogastrone which was earlier cloned in E. coli (Smith et al. 1982) has now been cloned into expression vectors for Bacillus subtilis Two types of constructs have been made, one giving production of methionylurogastrone and the other giving rise to a methionyl-urogastrone- galactosidase fusion polypeptide facilitating quantification of expression levels.The ribosome binding sites used in the expression plasmids are synthetically made oligonucleotides residing on short restriction fragments to allow easy replacement by other ribosome binding sites.Using shuttle vectors and constitutive promoters from Bacillus phages 105 and SPP1, we were able to detect levels of expression amounting to a few thousand molecules per cell during logarithmic growth in both E. coli and B. subtilis.     

Taxonomic identification of Streptomyces exfoliatus K10 and characterization of its poly(3-hydroxybutyrate) depolymerase gene

Abstract Using fungi grown on synthetic agar medium, we evaluated and compared the concentration of various H₂O₂-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 H₂O₂ production is ubiquitous in the white rot fungi tested and that enzyme levels are influenced by the substrate composition.     

23Na NMR study of the effect of organic osmolytes on DNA counterion atmosphere.

The effect of different organic osmolytes on the DNA counterion condensation layer has been investigated by 23Na NMR relaxation measurements. The zwitterionic compounds glycine, beta-alanine, 4-aminobutyric acid, and 6-aminocaproic acid have shown an increasing capacity to decrease the amount of sodium ions in the vicinity of the macromolecule. The experimental data have been correlated with the dielectric constant increase in their corresponding solutions and have been compared with the prediction of counterion condensation theory. Polyols (sorbitol and mannitol) did not display the same effect. These compounds largely increase the relaxation rate of sodium ions in the proximity of DNA, unlike the zwitterionic compounds. This probably results from a perturbation of the water dynamic around the macromolecule, of the primary or secondary hydration shell of the sodium nuclei involved, or both.     

Concentrations of Amino Acids in Extracellular Fluid After Opening of the Blood-Brain Barrier by Intracarotid Infusion of Protamine Sulfate

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.     

The effect of light levels on daily patterns of chlorophyll fluorescence and organic acid accumulation in the tropical CAM treeClusia hilariana

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 (q_N) 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 (q_A) in a low reduction state, similar to that of shaded plants. As a result, there was a moderate increase in the reduction state of q_A 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 (F_v/F_m) and their rapid recovery after sunset. However, the depletion of the organic acid pool in the afternoon resulted in an accentuated subsequent drop in F_v/F_m, 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.