Mucosal lymphatic-derived gammadelta T cells respond early to experimental Salmonella enterocolitis by increasing expression of IL-2R alpha

To better understand the roles of gammadelta T cells in mucosal infection, we utilized Salmonella enterica serovar Typhimurium (Salmonella serovar Typhimurium) infection in cattle as it closely approximates Salmonella serovar Typhimurium-induced enterocolitis in humans. Protein and gene expression in alphabeta and gammadelta T cells derived from lymphatic ducts draining the gut mucosa in Salmonella serovar Typhimurium-infected calves were analyzed. In calves with enterocolitis, general gene expression trends in gammadelta T cells suggested subtle activation and innate response, whereas alphabeta T cells were relatively quiescent following Salmonella serovar Typhimurium infection. An increase in IL-2R alpha expression on gammadelta T cells from infected calves and results from in vitro assays suggested that gammadelta T cells were primed by Salmonella serovar Typhimurium LPS to better respond to IL-2 and IL-15. Together with gene expression trends in vivo, these data support early priming activation of target tissue gammadelta T cells during Salmonella serovar Typhimurium infection.     

Cell division versus cell elongation: the control of radicle elongation during thermoinhibition of Tagetes minuta achenes

Endogenous embryo factors, which act mainly in the radicle, prevent germination in Tagetes minuta at high temperatures. These factors act to prevent cell elongation, which is critical for radicle protrusion under optimal conditions. Once the radicle has emerged both cell elongation and cell division are required for post-germination growth. Germination can be induced at high temperatures by fusicoccin, which rapidly stimulates cell elongation. In addition, priming seeds at 25 °C on polyethylene glycol (PEG) 6000 and mannitol could also induce germination on water at 36 °C, indicating that priming prevents radicle protrusion at a point subsequent to the point of control in thermoinhibited achenes. Flow cytometry studies revealed that DNA synthesis occurs during thermoinhibition and the inhibition of DNA synthesis during this process inhibits subsequent germination on water under optimal conditions, suggesting a protective role for DNA synthesis in thermoinhibited achenes of T. minuta.     

Effects of glucocorticoids on the respiratory burst of Chlamydia-primed THP-1 cells

We previously observed that the respiratory burst of human monocytes (THP-1 cell line) triggered by phorbol myristate acetate was strongly enhanced by a priming of the cells by Chlamydia pneumoniae [Biochem. Biophys. Res. Commun. 287 (2001) 781]. We describe here the modifications of the responses of Chlamydia-primed THP-1 cells to hydrocortisone (HCT) and methylprednisolone (MPL). HCT and MPL inhibited the production of the cytokines TNFα and IL-8. But HCT, which inhibited the respiratory burst in LPS-primed monocytes, paradoxically stimulated the phenomenon in Chlamydia-primed cells; MPL exerted no significant effect. Both glucocorticoids did not significantly modify the triggering effect of Chlamydia on NF-κB binding activity. On the expression of p22^phox, a protein subunit of the NADPH oxidase, HCT had an increasing and MPL a decreasing effect. Glucocorticoids thus had unexpected effects on the inflammatory response of Chlamydia-primed monocytes.     

Exopolysaccharides of Pantoea agglomerans have different priming and eliciting activities in suspension-cultured cells of monocots and dicots

Induced disease resistance of plants is often associated with an enhanced capacity to activate cellular defense responses to pathogen attack, named the "primed" state of the plant. Exopolysaccharides of Pantoea agglomerans have recently been reported as the first priming active component of bacterial origin in wheat cells. We now show that Pantoea exopolysaccharides also prime rice cells for better elicitation of a rapid oxidative burst. In contrast, in tobacco and parsley cell cultures Pantoea exopolysaccharides activate the oxidative burst response directly. Our results point to a different recognition and/or mode of action of Pantoea exopolysaccharides in monocot and dicot plants.     

Dynamics of the semantic priming shift: behavioral experiments and cortical network model

Multiple semantic priming processes between several related and/or unrelated words are at work during the processing of sequences of words. Multiple priming generates rich dynamics of effects depending on the relationship between the target word and the first and/or second prime previously presented. The experimental literature suggests that during the on-line processing of the primes, the activation can shift from associates to the first prime to associates to the second prime. Though the semantic priming shift is central to the on-line and rapid updating of word meanings in the working memory, its precise dynamics are still poorly understood and it is still a challenge to model how it functions in the cerebral cortex. Four multiple priming experiments are proposed that cross-manipulate delays and association strength between the primes and the target. Results show for the first time that association strength determines complex dynamics of the semantic priming shift, ranging from an absence of a shift to a complete shift. A cortical network model of spike frequency adaptive neuron populations is proposed to account for the non-continuous evolution of the priming shift over time. It allows linking the dynamics of the priming shift assessed at the behavioral level to the non-linear dynamics of the firing rates of neurons populations.     

Xylosylated naphthoic acid-amino acid conjugates for investigation of glycosaminoglycan priming

Three different series of xylosylated naphthoic acid-amino acid conjugates containing one or two amino acid residues were synthesized for the investigation of glycosaminoglycan priming and potential use as anti-tumor drugs. All xylosylated naphthoic acid-conjugates inhibited the growth of normal lung fibroblasts to some extent, whereas the growth of tumor derived T24 carcinoma cells was not affected. There was no correlation between amino acid conjugation, retention time and the antiproliferative activity. Only one compound initiated the priming of glycosaminoglycans. Modification of the naphthalene ring with one or two amino acid residues did not have any effect on proteoglycan biosynthesis or glycosaminoglycan priming in T24 carcinoma cells.     

Preparation of Secretory Vesicle-Free Plasma Membranes by Isopycnic Sucrose Gradient Fractionation of Neutrophils Purified by the Gelatin Method

Isolated human neutrophils serve as a model for the in vitro study of host defensive processes as well as the cell biology and biochemistry of primary human cells. We demonstrate that the requirements of the gelatinbased procedure for neutrophil isolation from whole blood induces the complete loss of secretory vesicles from in vitro isolated populations, whereas isolation by a dextran-based methodology results in the preservation of this organelle. Following density fractionation of cellular cavitates, examination of commonly employed plasma membrane marker activities yielded subcellular localization patterns that were indistinguishable between dextran- or gelatin-isolated populations, indicating both populations to be otherwise comparable in terms of the relative complexity and large-scale organization of plasma membranes. Given that the cell surface upregulation of secretory vesicles is implicated as an initial requirement of neutrophil activation as well as an intrinsic feature of neutrophil priming, we show that dextran and gelatin-isolated neutrophils may be considered to occupy functionally nonactivated and primed cellular states, respectively. These differences in phenotype can be exploited in specific ways. We suggest that the gelatin method has technical advantages with regard to the study of neutrophil plasma membranes. In particular, results from this study indicate the gelatin method to be a reliable and effective preparatory technique appropriate for tandem use with density fractionation procedures to achieve rapid isolation of plasma membranes that are uncontaminated by secretory organelles.     

Priming fingerprint induced by Bacillus amyloliquefaciens QV15, a common pattern in Arabidopsis thaliana and in field-grown blackberry

The aim of this study is focused on determining the Bacillus amyloliquefaciens QV15 priming fingerprint in two different plant species, Arabidopsis and blackberry as a crop of agronomic interest, associated with protection upon pathogen challenge. To achieve this goal, Arabidopsis thaliana plants were challenged with Pseudomonas syringae DC3000 under controlled conditions, and field-grown blackberries were challenged by a powdery Mildew outbreak, finding plant protection in plants treated with QV15, in both conditions. Changes in ROS scavenging enzymes’ activity, defense-related enzymes’ activity and gene expression were evaluated in both plant species, before and after pathogen challenge, revealing the ability of this strain to prime both. As a result of this analysis, the priming fingerprint induced by QV15 was defined by a decrease in ROS scavenging enzymes’ activity in pre- and post-challenged plants, an increase in glucanase and chitinase activity after pathogen challenge, significantly increasing the expression of PR1, indicating a salicylic acid (SA)-mediated pathway activation. These results suggest an excellent potential of B. amyloliquefaciens QV15 to protect different plant species against different pathogens in field conditions.     

Application of Beneficial Microorganisms to Seeds during Drum Priming

Five microbial plant growth promoters or biocontrol agents (Pseudomonas fluorescens CHA0, Pseudomonas sp. AB842, Bacillus subtilis MBI600, Trichoderma harzianum T22 and T. virens G20) were assessed for ability to proliferate on seeds of carrot, parsnip and leek. In small-scale priming systems, both pseudomonads and MBI600 (when applied as cells) at levels between 10⁵ and 10⁶ cfu g^?1 seed were able to colonise all seeds at the end of priming (240 h) despite initial poor recovery after addition of the cells in some cases. Pf CHA0 was a particularly aggressive seed coloniser often comprising the total pseudomonad population at the end of priming. Drying the seed after priming resulted in <1 log₁₀ cfu g^?1 seed loss for the pseudomonads but greater losses for MBI600 on carrot and leek seed. Application of spores of MBI600 resulted in little loss in cfu g^?1 seed following addition of the cells and these levels were maintained throughout the priming period and after drying back. Both T22 and G20 were recovered from carrot and parsnip at the end of priming and in general reflected survival of the inoculum rather than proliferation. T22 and G20 could not be recovered from leek seed following priming. Comparisons were made between proliferation and survival in large-scale drum priming with post-priming application of microorganisms. Pf CHA0 proliferated on carrot and parsnip seed during drum priming and survived the drying back process whereas there was no recovery when applied as a post-priming treatment. In contrast, MBI600 could not be recovered when applied during priming as cells, whereas recovery was good when applied post-priming as spores. T22 spores could be applied in either manner. Post-priming application of metalaxyl and thiabendazole had variable effects on microorganism recovery. The significance of the application of microorganisms to seeds during priming is discussed.     

Exploring the priming mechanism of liver regeneration: proteins and protein complexes

The liver has the ability to restore its functional capacity following injury or resection and the priming of liver regeneration is a complex process that has not been completely elucidated. In the current research, to further reveal the priming mechanism of liver regeneration, hepatocyte total protein and hepatocyte cytosol of the rats at 4 h after 2/3 partial hepatectomy (PHx) were studied, respectively, by 2‐DE and 2‐D blue native gel electrophoresis. Seventeen unique differential proteins were identified in hepatocyte total protein samples. Nine differential protein complexes containing 41 protein components were identified in hepatocyte cytosol samples. For the first time, at the priming stage of liver regeneration, the variations of serine protease inhibitor 2c, sulfite oxidase and valosin‐containing protein (VCP) were presented and validated by Western blotting, and the VCP complex was further validated by antibody super‐shift experiments. The current results suggested that at 4 h after PHx, VCP complex was down‐regulated in hepatocyte cytosol, apoptosis pathways were inhibited, nuclear factor‐κB and interleukin 6 pathways worked together and triggered the liver regeneration.