Growth-phase regulation of lipopolysaccharide O-antigen chain length influences serum resistance in serovars of Salmonella

The amount of lipopolysaccharide (LPS) O antigen (OAg) and its chain length distribution are important factors that protect bacteria from serum complement. Salmonella enterica serovar Typhi produces LPS with long chain length distribution (L-OAg) controlled by the wzz gene, whereas serovar Typhimurium produces LPS with two OAg chain lengths: an L-OAg controlled by Wzz(ST) and a very long (VL) OAg determined by Wzz(fepE). This study shows that serovar Enteritidis also has a bimodal OAg distribution with two preferred OAg chain lengths similar to serovar Typhimurium. It was reported previously that OAg production by S. Typhi increases at the late exponential and stationary phases of growth. The results of this study demonstrate that increased amounts of L-OAg produced by S. Typhi grown to stationary phase confer higher levels of bacterial resistance to human serum. Production of OAg by serovars Typhimurium and Enteritidis was also under growth-phase-dependent regulation; however, while the total amount of OAg increased during growth, the VL-OAg distribution remained constant. The VL-OAg distribution was primarily responsible for complement resistance, protecting the non-typhoidal serovars from the lytic action of serum irrespective of the growth phase. As a result, the non-typhoidal species were significantly more resistant than S. Typhi to human serum. When S. Typhi was transformed with a multicopy plasmid containing the S. Typhimurium wzz(fepE) gene, resistance to serum increased to levels comparable to the non-typhoidal serovars. In contrast to the relevant role for high-molecular-mass OAg molecules, the presence of Vi antigen did not contribute to serum resistance of clinical isolates of serovar Typhi.

RpoS and RpoN are involved in the growth-dependent regulation of rfaH transcription and O antigen expression in Salmonella enterica serovar Typhi

We reported earlier that the production of O antigen lipopolysaccharide (LPS) by Salmonella enterica serovar Typhi (Salmonella typhi) increases at the onset of stationary phase and correlates with a growth-regulated expression of the rfaH gene under the control of the alternative sigma factor RpoN (Microbiology 148 (2002) 3789). In this study, we demonstrate that RpoS also modulates rfaH promoter activity as revealed by the absence of growth-dependent regulation of an rfaH-lacZ transcriptional fusion and O antigen production in a S. typhi rpoS mutant. Introduction of a constitutively expressed rpoN gene into the rpoS mutant restored increased production of O antigen during stationary phase, suggesting that constitutive production of RpoN could overcome the RpoS defect. Similar results were observed when an rpoS rpoN double mutant was transformed with the intact rpoN gene. Thus, we conclude that both RpoS and RpoN control the rfaH promoter activity and concomitantly, the production of O-specific LPS in S. typhi.

Regulatory or Regulating Publics? The European Union’s Regulation of Emerging Health Technologies and Citizen Participation

‘Citizen participation’ includes various participatory techniques and is frequently viewed as an unproblematic and important social good when used as part of the regulation of the innovation and implementation of science and technology. This is perhaps especially evident in debates around ‘anticipatory governance’ or ‘upstream engagement’. Here, we interrogate this thesis using the example of the European Union’s regulation of emerging health technologies (such as nanotechnology). In this case, citizen participation in regulatory debate is concerned with innovative objects for medical application that are considered to be emergent or not yet concrete. Through synthesising insights from law, regulatory studies, critical theory, and science and technology studies (STS), we seek to cast new light on the promises, paradoxes and pitfalls of citizen participation as a tool or technology of regulation in itself. As such we aim to generate a new vantage point from which to view the values and sociotechnical imaginaries that are both ‘designed-in’ and ‘designed-out’ of citizen participation. In so doing, we show not only how publics (do not) regulate technologies, but also how citizens themselves are regulated through the techniques of participation. © The Author [2012].

Posttranscriptional regulation of acute phase serum amyloid A2 expression by the 5'- and 3'-untranslated regions of its mRNA

Human acute-phase serum amyloid A protein (A-SAA) is a major acute phase reactant, the concentration of which increases dramatically as part of the body's early response to inflammation. A-SAA is the product of two almost identical genes, SAA1 and SAA2, which are induced by the pro-inflammatory cytokines, IL-1 and IL-6. In this study, we examine the roles played by the 5'- and 3'-untranslated regions (UTRs) of the SAA2 mRNA in regulating A-SAA2 expression. SAA2 promoter-driven luciferase reporter gene constructs carrying the SAA2 5'-UTR and/or 3'-UTR were transiently transfected into the HepG2 human hepatoma cell line. After induction of chimeric mRNA with IL-1beta and IL-6, the SAA2 5'- and 3'-UTRs were both able to posttranscriptionally modify the expression of the luciferase reporter. The SAA2 5'-UTR promotes efficient translation of the chimeric luciferase transcripts, whereas the SAA2 3'-UTR shares this property and also significantly accelerates the rate of reporter mRNA degradation. Our data strongly suggest that the SAA2 5'- and 3'-UTRs each play significant independent roles in the posttranscriptional regulation of A-SAA2 protein synthesis.

Up-regulation of the endothelial cell adhesion molecule intercellular adhesion molecule-1 (ICAM-1) by autoantibodies in autoimmune vasculitis

Autoimmune vasculitis is characterized by the presence of autoantibodies, particularly anti-neutrophil cytoplasmic antibodies (ANCA) and anti-nuclear antibodies (ANA), in patient sera. These autoantibodies have an incompletely understood role in development of vascular injury. The expression or up-regulation of cell adhesion molecules is an early phase in the development of an inflammatory vascular lesion. Autoantibody-positive sera from patients with vasculitis were assessed for their ability to modulate adhesion molecule expression by human umbilical vein endothelial cells (HUVEC). Autoantibody-positive serum samples from 11 out of 21 patients with primary vasculitis produced substantial up-regulation of ICAM-1 on HUVEC. Autoantibody-negative samples did not produce adhesion molecule up-regulation. Up-regulation of adhesion molecules on HUVEC was observed with samples positive for ANA, a phenomenon not previously reported. Preincubation of the sera with purified antigens recognized by ANCA failed to block this activation. In addition, MoAbs to ANCA antigens were ineffective at inducing ICAM-1 up-regulation, suggesting that activation is independent of the molecular specificity of the antibody. This capacity of ANCA- and ANA-positive sera to up-regulate adhesion molecules on endothelial cells may be a factor in the vessel wall inflammation seen in ANCA-associated vasculitis.

Up-regulation of the granulocyte adhesion molecule Mac-1 by autoantibodies in autoimmune vasculitis

The characteristic finding of autoantibodies in patients with vasculitis has raised the possibility that these antibodies play a role in the pathogenesis of the disease. The expression of adhesion molecules (AM) on leucocytes and endothelial cells is believed to be integral to the development of vasculitis. We therefore investigated the effect of sera, positive for anti-neutrophil cytoplasmic antibodies (ANCA) or anti-nuclear antibodies (ANA) from patients with vasculitis, on granulocyte expression of the adhesion molecule Mac-1 (CD11b). Autoantibody-positive sera from 15 out of 35 patients with vasculitis stimulated an up-regulation of Mac-1 on granulocytes. In most cases this effect was reproduced by the autoantibody-positive purified IgG fraction. Autoantibody-negative samples did not stimulate AM up-regulation. Of interest, preincubation of sera with purified antigens did not inhibit AM up-regulation by the autoantibody samples. Blocking the Fc receptors on granulocytes did result in a decrease of Mac-1 up-regulation, but this trend was not statistically significant. These results suggest that both ANCA and ANA have the capacity to up-regulate granulocyte AM expression, and that while Fc interaction with granulocyte Fc receptors is important, it is not the only mechanism whereby such autoantibodies activate cells.

Regulation of Epithelial Differentiation and Proliferation by the Stroma: A Role for the Retinoblastoma Protein.

Signaling between the epithelium and stromal cells is crucial for growth, differentiation, and repair of the epithelium. Although the retinoblastoma protein (Rb) is known to regulate the growth of keratinocytes in a cell-autonomous manner, here we describe a function of Rb in the stromal compartment. We find that Rb depletion in fibroblasts leads to inhibition of differentiation and enhanced proliferation of the epithelium. Analysis of conditioned medium identified that keratinocyte growth factor (KGF) levels were elevated following Rb depletion. These findings were also observed with organotypic co-cultures. Treatment of keratinocytes with KGF inhibited differentiation and enhanced keratinocyte proliferation, whereas reduction of KGF levels in Rb-depleted fibroblasts was able to restore expression of differentiation markers. Our findings suggest a crucial role for dermal fibroblasts in regulating the differentiation and proliferation of keratinocytes, and we demonstrate a role for stromal Rb in this cross-talk.Journal of Investigative Dermatology advance online publication, 14 June 2012;doi:10.1038/jid.2012.201.

Transcriptional regulation of a brown adipocyte-specific gene, UCP1, by KLF11 and KLF15

Several growth factors and transcription factors have been reported to play important roles in brown adipocyte differentiation and modulation of thermogenic gene expression, especially the expression of UCP1. In this study, we focused on KLF11 and KLF15, which were expressed highly in brown adipose tissue. Our data demonstrated that KLF11 and KLF15 interacted directly with the UCP1 promoter using GC-box and GT-boxes, respectively. Co-transfection of KLF11 and KLF15 in the mesenchymal stem cell line muBM3.1 during brown adipocyte differentiation enhanced the expression level of UCP1. KLF11, but not KLF15, was essential for UCP1 expression during brown adipocyte differentiation of muBM3.1.

Spatial Heterogeneity and Kinetic Regulation of Arsenic Dynamics in Mangrove Sediments: The Sundarbans, Bangladesh

The biogeochemistry of arsenic (As) in sediments is regulated by multiple factors such as particle size, dissolved organic matter (DOM), iron mobilization, and sediment binding characteristics, among others. Understanding the heterogeneity of factors affecting As deposition and the kinetics of mobilization, both horizontally and vertically, across sediment depositional environments was investigated in Sundarban mangrove ecosystems, Bengal Delta, Bangladesh. Sediment cores were collected from 3 different Sundarbans locations and As concentration down the profiles were found to be more associated with elevated Fe and Mn than with organic matter (OM). At one site chosen for field monitoring, sediment cores, pore and surface water, and in situ diffusive gradients in thin films (DGT) measurements (which were used to model As sediment pore-water concentrations and resupply from the solid phase) were sampled from four different subhabitats. Coarse-textured riverbank sediment porewaters were high in As, but with a limited resupply of As from the solid phase compared to fine-textured and high organic matter content forest floor sediments, where porewater As was low, but with much higher As resupply. Depositional environment (overbank verses forest floor) and biological activity (input of OM from forest biomass) considerably affected As dynamics over very short spatial distances in the mosaic of microhabitats that constitute a mangrove ecosystem.

Regulation of arsenic mobility on basaltic glass surfaces by speciation and pH

The importance of geothermal energy as a source for electricity generation and district heating has increased over recent decades. Arsenic can be a significant constituent of the geothermal fluids pumped to the surface during power generation. Dissolved As exists in different oxidation states, mainly as As(III) and As(V), and the charge of individual species varies with pH. Basaltic glass is one of the most important rock types in many high-temperature geothermal fields. Static batch and dynamic column experiments were combined to generate and validate sorption coefficients for As(III) and As(V) in contact with basaltic glass at pH 3-10. Validation was carried out by two empirical kinetic models and a surface complexation model (SCM). The SCM provided a better fit to the experimental column data than kinetic models at high pH values. However, in certain circumstances, an adequate estimation of As transport in the column could not be attained without incorporation of kinetic reactions. The varying mobility with pH was due to the combined effects of the variable charge of the basaltic glass with the pH point of zero charge at 6.8 and the individual As species as pH shifted, respectively. The mobility of As(III) decreased with increasing pH. The opposite was true for As(V), being nearly immobile at pH 3 to being highly mobile at pH 10. Incorporation of appropriate sorption constants, based on the measured pH and Eh of geothermal fluids, into regional groundwater-flow models should allow prediction of the As(III) and As(V) transport from geothermal systems to adjacent drinking water sources and ecosystems.

Autonomy and regulation of state agencies:Reinforcement, indifference or compensation?

This paper analyses the relationships between the autonomy and regulation of state agencies in Norway, Ireland and Flanders (Belgium). The empirical basis is provided by broad surveys of public sector organizations carried out in 2002-2004. Three hypotheses on these relationships are formulated and examined, indicating different patterns. The reinforcement hypothesis, stating a negative relationship does not get any support. On the other hand, the compensation hypothesis, stating a positive relationship gets some support. In general, however, the indifference hypothesis, stating low or no correlations seems to be the most adequate. The hypotheses are also linked to prevalent administrative doctrines, and the empirical findings indicate how relevant they are. © Springer Science+Business Media, LLC 2008.

The up-regulation of voltage-gated sodium channels subtypes coincides with an increased sodium current in hippocampal neuronal culture model

Voltage-gated sodium channels (VGSC) have been linked to inherited forms of epilepsy. The expression and biophysical properties of VGSC in the hippocampal neuronal culture model have not been clarified. In order to evaluate mechanisms of epileptogenesis that are related to VGSC, we examined the expression and function of VGSC in the hippocampal neuronal culture model in vitro and spontaneously epileptic rats (SER) in vivo. Our data showed that the peak amplitude of transient, rapidly–inactivating Na+ current (INa,T) in model neurons was significantly increased compared with control neurons, and the activation curve was shifted to the negative potentials in model neurons in whole cell recording by patch–clamp. In addition, channel activity of persistent, non-inactivating Na+ current (INa,P) was obviously increased in the hippocampal neuronal culture model as judged by single–channel patch–clamp recording. Furthermore, VGSC subtypes NaV1.1, NaV1.2 and NaV1.3 were up-regulated at the protein expression level in model neurons and SER as assessed by Western blotting. Four subtypes of VGSC proteins in SER were clearly present throughout the hippocampus, including CA1, CA3 and dentate gyrus regions, and neurons expressing VGSC immunoreactivity were also detected in hippocampal neuronal culture model by immunofluorescence. These findings suggested that the up-regulation of voltage-gated sodium channels subtypes in neurons coincided with an increased sodium current in the hippocampal neuronal culture model, providing a possible explanation for the observed seizure discharge and enhanced excitability in epilepsy.