Molecular control of vertebrate iron metabolism: mRNA-based regulatory circuits operated by iron, nitric oxide, and oxidative stress.

As an essential nutrient and a potential toxin, iron poses an exquisite regulatory problem in biology and medicine. At the cellular level, the basic molecular framework for the regulation of iron uptake, storage, and utilization has been defined. Two cytoplasmic RNA-binding proteins, iron-regulatory protein-1 (IRP-1) and IRP-2, respond to changes in cellular iron availability and coordinate the expression of mRNAs that harbor IRP-binding sites, iron-responsive elements (IREs). Nitric oxide (NO) and oxidative stress in the form of H2O2 also signal to IRPs and thereby influence cellular iron metabolism. The recent discovery of two IRE-regulated mRNAs encoding enzymes of the mitochondrial citric acid cycle may represent the beginnings of elucidating regulatory coupling between iron and energy metabolism. In addition to providing insights into the regulation of iron metabolism and its connections with other cellular pathways, the IRE/IRP system has emerged as a prime example for the understanding of translational regulation and mRNA stability control. Finally, IRP-1 has highlighted an unexpected role for iron sulfur clusters as post-translational regulatory switches.

Regulation of herbivore growth by the balance of light and nutrients.

Experiments using planktonic organisms revealed that the balance of radiant energy and available nutrients regulated herbivore growth rates through their effects on abundance and chemical composition of primary producers. Both algae and herbivores were energy limited at low light/nutrient ratios, but both were nutrient limited at high light/nutrient ratios. Herbivore growth increased with increasing light intensity at low values of the light/nutrient ratio due to increases in algal biomass, but growth decreased with increasing light at a high light/nutrient ratio due to decreases in algal quality. Herbivore production therefore was maximal at intermediate levels of the light/nutrient ratio. The results contribute to an understanding of mass transfer mechanisms in ecosystems and illustrate the importance of integration of energy-based and material-based currencies in ecology.

N2 fixation in marine heterotrophic bacteria: dynamics of environmental and molecular regulation.

Molecular and immunological techniques were used to examine N2 fixation in a ubiquitous heterotrophic marine bacterium, the facultative anaerobic Vibrio natriegens. When batch cultures were shifted from aerobic N-replete to anaerobic N-deplete conditions, transcriptional and post-translational regulation of N2 fixation was observed. Levels of nifHDK mRNA encoding the nitrogenase enzyme were highest at 140 min postshift and undetectable between 6 and 9 h later. Immunologically determined levels of nitrogenase enzyme (Fe protein) were highest between 6 and 15 h postshift, and nitrogenase activity peaked between 6 and 9 h postshift, declining by a factor of 2 after 12-15 h. Unlike their regulation in cyanobacteria, Fe protein and nitrogenase activity were present when nifHDK mRNA was absent in V. natriegens, indicating that nitrogenase is stored and stable under anaerobic conditions. Both nifHDK mRNA and Fe protein disappeared within 40 min after cultures were shifted from N2-fixing conditions (anaerobic, N-deplete) to non- N2-fixing conditions (aerobic, N-enriched) but reappeared when shifted to conditions favoring N2 fixation. Thus, unlike other N2-fixing heterotrophic bacteria, nitrogenase must be resynthesized after aerobic exposure in V. natriegens. Immunological detection based on immunoblot (Western) analysis and immunogold labeling correlated positively with nitrogenase activity; no localization of nitrogenase was observed. Because V. natriegens continues to fix N2 for many hours after anaerobic induction, this species may play an important role in providing "new" nitrogen in marine ecosystems.

Azotobacter vinelandii NIFL is a flavoprotein that modulates transcriptional activation of nitrogen-fixation genes via a redox-sensitive switch.

The NIFL regulatory protein controls transcriptional activation of nitrogen fixation (nif) genes in Azotobacter vinelandii by direct interaction with the enhancer binding protein NIFA. Modulation of NIFA activity by NIFL, in vivo occurs in response to external oxygen concentration or the level of fixed nitrogen. Spectral features of purified NIFL and chromatographic analysis indicate that it is a flavoprotein with FAD as the prosthetic group, which undergoes reduction in the presence of sodium dithionite. Under anaerobic conditions, the oxidized form of NIFL inhibits transcriptional activation by NIFA in vitro, and this inhibition is reversed when NIFL is in the reduced form. Hence NIFL is a redox-sensitive regulatory protein and may represent a type of flavoprotein in which electron transfer is not coupled to an obvious catalytic activity. In addition to its ability to act as a redox sensor, the activity of NIFL is also responsive to adenosine nucleotides, particularly ADP. This response overrides the influence of redox status on NIFL and is also observed with refolded NIFL apoprotein, which lacks the flavin moiety. These observations suggest that both energy and redox status are important determinants of nif gene regulation in vivo.

A model for the transcriptional regulation of the CYP2B1/B2 gene in rat liver.

The phenobarbitone-responsive minimal promoter has been shown to lie between nt -179 and nt + 1 in the 5' (upstream) region of the CYP2B1/B2 gene in rat liver, on the basis of the drug responsiveness of the sequence linked to human growth hormone gene as reporter and targeted to liver as an asialoglycoprotein-DNA complex in vivo. Competition analyses of the nuclear protein-DNA complexes formed in gel shift assays with the positive (nt -69 to -98) and negative (nt -126 to -160) cis elements (PE and NE, respectively) identified within this region earlier indicate that the same protein may be binding to both the elements. The protein species purified on PE and NE affinity columns appear to be identical based on SDS/PAGE analysis, where it migrates as a protein of 26-28 kDa. Traces of a high molecular weight protein (94-100 kDa) are also seen in the preparation obtained after one round of affinity chromatography. The purified protein stimulates transcription of a minigene construct containing the 179 nt on the 5' side of the CYP2B1/B2 gene linked to the I exon in a cell-free system from liver nuclei. The purified protein can give rise to all the three complexes (I, II, and III) with the PE, just as the crude nuclear extract, under appropriate conditions. Manipulations in vitro indicate that the NE has a significantly higher affinity for the dephosphorylated form than for the phosphorylated form of the protein. The PE binds both forms. Phenobarbitone treatment of the animal leads to a significant increase in the phosphorylation of the 26- to 28-kDa and 94-kDa proteins in nuclear labeling experiments followed by isolation on a PE affinity column. We propose that the protein binding predominantly to the NE in the dephosphorylated state characterizes the basal level of transcription of the CYP2B1/B2 gene. Phenobarbitone treatment leads to phosphorylation of the protein, shifting the equilibrium toward binding to the PE. This can promote interaction with an upstream enhancer through other proteins such as the 94-kDa protein and leads to a significant activation of transcription.

Agouti regulation of intracellular calcium: role in the insulin resistance of viable yellow mice.

Several dominant mutations at the agouti locus in the mouse cause a syndrome of marked obesity, hyperinsulinemia, and insulin resistance. Although it is known that the agouti gene is expressed in an ectopic manner in these mutants, the precise mechanism by which the agouti gene product mediates these effects is unclear. Since intracellular Ca2+ is believed to play a role in mediating insulin action and dysregulation of Ca2+ flux is observed in diabetic animals and humans, we examined the status of intracellular Ca2+ in mice carrying the dominant agouti allele, viable yellow (Avy). We show here that in mice carrying this mutation, the intracellular free calcium concentration ([Ca2+]i) is elevated in skeletal muscle, and the degree of elevation is closely correlated with the degree to which the mutant traits are expressed in individual animals. Moreover, we demonstrate that the agouti gene product is capable of inducing increased [Ca2+]i in cultured and freshly isolated skeletal muscle myocytes from wild-type mice. Based on these findings, we present a model in which we propose that the agouti polypeptide promotes insulin resistance in mutant animals through its ability to increase [Ca2+]i.

A Meta-Analytic Review of Mindfulness-Based Interventions on Symptom Reduction: A Critique and Guide for Future Investigation.

Over the past decade, mindfulness practices have been used with increasing frequency as therapeutic components within cognitive behavioral treatment regimens. As is standard practice, prescriptive uses of mindfulness intervention are incorporated to improve end-state functioning by ameliorating problematic symptoms and conditions. Common change-targets include the control of cognitive and emotional content for purposes of enhancing psychological self-regulation and physical well-being. The term mindfulness applies to a heterogeneous range of practices, methods, and techniques. While there is no singular agreed upon definition for mindfulness, as a process concept, the term connotes an immediate, non-thetic access to events, wherein each occasioning event is experienced in toto within the broader contextual event-field, and distinct from intervening conceptual themes being noticed. Training in mindfulness practices may be conducted using individual, group, or small class formats. The current paper provides a meta-analytic review of 44 treatment outcome studies (extracted 1982 through 2006), which examines the clinical utility of mindfulness as the primary therapeutic approach. Results indicated that average effect sizes for mindfulness based interventions fell within the medium range for construct category variables examined (d = .56). These findings suggest that mindfulness training is a cost-effective treatment for a wide array of contemporary psychological problems and diagnoses, in addition to fostering positive psychology attributes such as quality and satisfaction with life. A critique of the research and recommendations for future research, including a need to examine the role of mindfulness as a tool for cultivating increased psychological acceptance and life satisfaction, is presented.

Multi-agent system for control of robots inspired on the distributed activity and hormonal regulation of humans

Robotics is an emerging field with great activity. Robotics is a field that presents several problems because it depends on a large number of disciplines, technologies, devices and tasks. Its expansion from perfectly controlled industrial environments toward open and dynamic environment presents a many new challenges. New uses are, for example, household robots or professional robots. To facilitate the low cost, rapid development of robotic systems, reusability of code, its medium and long term maintainability and robustness are required novel approaches to provide generic models and software systems who develop paradigms capable of solving these problems. For this purpose, in this paper we propose a model based on multi-agent systems inspired by the human nervous system able to transfer the control characteristics of the biological system and able to take advantage of the best properties of distributed software systems. Specifically, we model the decentralized activity and hormonal variation.

Nitrogen regulation of protein–protein interactions and transcript levels of GlnK PII regulator and AmtB ammonium transporter homologs in Archaea

Gene homologs of GlnK PII regulators and AmtB-type ammonium transporters are often paired on prokaryotic genomes, suggesting these proteins share an ancient functional relationship. Here, we demonstrate for the first time in Archaea that GlnK associates with AmtB in membrane fractions after ammonium shock, thus, providing a further insight into GlnK-AmtB as an ancient nitrogen sensor pair. For this work, Haloferax mediterranei was advanced for study through the generation of a pyrE2-based counterselection system that was used for targeted gene deletion and expression of Flag-tagged proteins from their native promoters. AmtB1-Flag was detected in membrane fractions of cells grown on nitrate and was found to coimmunoprecipitate with GlnK after ammonium shock. Thus, in analogy to bacteria, the archaeal GlnK PII may block the AmtB1 ammonium transporter under nitrogen-rich conditions. In addition to this regulated protein–protein interaction, the archaeal amtB-glnK gene pairs were found to be highly regulated by nitrogen availability with transcript levels high under conditions of nitrogen limitation and low during nitrogen excess. While transcript levels of glnK-amtB are similarly regulated by nitrogen availability in bacteria, transcriptional regulators of the bacterial glnK promoter including activation by the two-component signal transduction proteins NtrC (GlnG, NRI) and NtrB (GlnL, NRII) and sigma factor σN (σ54) are not conserved in archaea suggesting a novel mechanism of transcriptional control.

The impact of marketing practices and its regulation policies on childhood obesity. Opinions of stakeholders in Spain

The aim of this study was to identify Spanish stakeholders’ views on the relationship between childhood obesity and the marketing and advertising of food and beverages aimed at children in Spain, as well as on the corresponding of regulations. We performed a qualitative study based on semi-structured interviews with Stakeholders/Key Informants (KI) from 13 organisations: experts (2), consumer advocates (1), public health advocates (2), food manufacturers (2), advertising advocates (1), government representatives (1), child/family/school advocates (2) and media (1). The variables studied were Prevalence of childhood obesity and its relationship to marketing/advertising and Regulation of marketing. In order to identify the most relevant arguments (pearls) in the discourses, a blind independent analysis by four members of the research team was performed. We found that the prevalence of childhood obesity was perceived to be higher than the European average. Self-regulation was identified as the main form of marketing control. Only food manufacturers and advertising agencies considered voluntary action and supervisory procedures to be effective. The other stakeholders advocated state control through legislation and non-state actions such as external assessment and sanctions. Despite the divergence of opinion between stakeholders, there was agreement on the need to improve supervision and to ensure compliance with current self-regulatory codes in Spain.

Transcriptional profiles of Haloferax mediterranei based on nitrogen availability

The haloarchaeon Haloferax mediterranei is able to grow in the presence of different inorganic and organic nitrogen sources by means of the assimilatory pathway under aerobic conditions. In order to identify genes of potential importance in nitrogen metabolism and its regulation in the halophilic microorganism, we have analysed its global gene expression in three culture media with different nitrogen sources: (a) cells were grown stationary and exponentially in ammonium, (b) cells were grown exponentially in nitrate, and (c) cells were shifted to nitrogen starvation conditions. The main differences in the transcriptional profiles have been identified between the cultures with ammonium as nitrogen source and the cultures with nitrate or nitrogen starvation, supporting previous results which indicate the absence of ammonium as the factor responsible for the expression of genes involved in nitrate assimilation pathway. The results have also permitted the identification of transcriptional regulators and changes in metabolic pathways related to the catabolism and anabolism of amino acids or nucleotides. The microarray data was validated by real-time quantitative PCR on 4 selected genes involved in nitrogen metabolism. This work represents the first transcriptional profiles study related to nitrogen assimilation metabolism in extreme halophilic microorganisms using microarray technology.

GATS and the Social Regulation of Services. IES WORKING PAPER 3/2010

Many service transactions are highly complex, and their quality is difficult to ascertain for consumers. In order to have properly functioning service markets, the services thus often require regulation. However, with the advent of the WTO, international trade in services has become increasingly rule-bound. GATS has considerable, intricate effects on social regulation due to the characteristics of services. The allocation of regulatory jurisdiction between home and host country, for example, is rendered difficult by the process-based nature of a lot of services. The WTO US – Gambling dispute settlement report is the first to address GATS disciplines on social regulation in a detailed manner. This working paper submits that the US - Gambling report has increased interference with domestic social regulation and created regulatory uncertainty for WTO members. However, it is also argued that the real impact of the GATS on social regulation can only be understood by looking beyond the text of the GATS. GATS disciplines may become amplified through their interaction with domestic and other international law. The GATS also contains some “political” counterbalancing mechanisms that allow members to renegotiate their commitments. It is argued that these political mechanisms strengthen subsidiarity in the GATS, and make WTO dispute settlement bodies accountable to WTO members.

Do Changes in Regulation Affect Employment Duration in Temporary Work Agencies? CES Germany & Europe Working Papers, No. 07.1, 2007

Over the past three decades Germany has repeatedly deregulated the law on temporary agency work by stepwise increasing the maximum period for hiring-out employees and allowing temporary work agencies to conclude fixed-term contracts. These reforms should have had an effect on employment duration within temporary work agencies. Based on an informative administrative data set we use a mixed proportional hazard rate model to examine whether employment duration has changed in response to these reforms. We find that the repeated prolongation of the maximum period for hiring-out employees significantly increased average employment duration while the authorization of fixed-term contracts reduced employment tenure.

What drives the European Parliament? The Case of the General Data Protection Regulation. Bruges Political Research Papers 47/2015.

This paper evaluates which factors influence the European Parliament’s decision-making, based on a case study: the 2012 proposal for a General Data Protection Regulation. Following a ‘competitive testing’ approach, six different hypotheses are successively challenged in order to explain why the EP adopted a fundamental rights- oriented position. The first three factors relate to the internal organization of the EP’s work, i.e. the role played by the lead committee, by the rapporteur and by secretariat officials. The last three factors are external-related, i.e. lobbying activities, outside events and institutional considerations. Based on the empirical findings, it is argued that even though the EP’s position is due to a range of various factors, some of them prove to be more relevant than others, in particular the rapporteur and lead committee’s roles. New institutionalism theories also provide a comprehensive explanation for the EP’s willingness to achieve a fundamental rights oriented outcome.

Organic matter based proxies from surface sediments along three transects on the Pakistan continental margin

A valid assessment of selective aerobic degradation on organic matter (OM) and its impact on OM-based proxies is vital to produce accurate environmental reconstructions. However, most studies investigating these effects suffer from inherent environmental heterogeneities. In this study, we used surface samples collected along two meter-scale transects and one longer transect in the northeastern Arabian Sea to constrain initial OM heterogeneity, in order to evaluate selective aerobic degradation on temperature, productivity and alteration indices at the sediment-water interface. All of the studied alteration indices, the higher plant alkane index, alcohol preservation index, and diol oxidation index, demonstrated that they are sensitive indicators for changes in the oxygen regime. Several export production indices, a cholesterol-based stanol/stenol index and dinoflagellate lipid- and cyst-based ratios, showed significant (more than 20%) change only over the lateral oxygen gradients. Therefore, these compounds do not exclusively reflect surface water productivity, but are significantly altered after deposition. Two of the proxies, glycerol dibiphytanyl glycerol tetraether-based TEX86 sea surface temperature indices and indices based on phytol, phytane and pristane, did not show any trends related to oxygen. Nevertheless, unrealistic sea surface temperatures were obtained after application of the TEX86, TEX86L, and TEX86H proxies. The phytol-based ratios were likely affected by the sedimentary production of pristane. Our results demonstrate the selective impact of aerobic organic matter degradation on the lipid and palynomorph composition of surface sediments along a short lateral oxygen gradient and suggest that some of the investigated proxies may be useful tracers of changing redox conditions at the sediment-water interface.