Mutual activation of two restriction endonucleases: interaction of EcoP1 and EcoP15

Type III restriction endonucleases recognize nonsymmetric nucleotide sequences. A necessary condition for DNA cleavage is the presence of two unmethylated recognition sites which are inversely ('head-to-head') oriented in the DNA double strand. A DNA substrate possessing one EcoP1 and one EcoP15 site in the head-to-head configuration could not be cleaved by the individual enzymes, however, it was specifically digested in the simultaneous presence of both enzymes. In agreement with the tracking-collision model for the DNA interaction of type III enzymes cleavage could be abolished by Lac repressor bound between the two sites. We conclude that two different type III enzymes can functionally cooperate in the cleavage of DNA.     

An experimental selection system to identify bacterial cells exhibiting a new DNA host specificity

Restriction-modification enzymes interact with DNA sequences in a highly specific manner. Mutations within the DNA binding region of the enzymes could be expected to produce enzyme variants with changed DNA sequence specificities. We developed an efficient in vivo selection system that enabled us to detect one cell coding for a restriction-modification system with a new DNA sequence specificity in a background of more than 10(6) cells with the original DNA sequence specificity.     

Expression and characterization of three important panallergens from hazelnut

Several hazelnut allergens with different clinical relevance and crossreactive properties have been identified and characterized so far. The aim of this study was to develop protocols for producing relatively large amounts of three recombinant hazelnut allergens Cor a 1.04, Cor a 2, and Cor a 8 in a folded and immunologically active form. The availability of well-characterized, pure recombinant allergens will improve diagnostic in vitro tests for food allergy, by allowing a highly sensitive component resolved diagnosis. Depending on the individual hazelnut allergen, protocols for heterologous production - either as fusion or nonfusion protein - were developed to obtain homogenous protein batches. The resulting proteins were purified by a two-step FPLC method and their IgE antibody reactivity was verified. Identity was verified by N-terminal sequencing and MALDI-TOF-MS analysis. Their secondary and tertiary structure was controlled by circular dichroism (CD)-spectroscopy and NMR analysis. Decisions on the strategies for expression and purification of allergens on a large scale were made on a case by case basis: Preparation of rCor a 1.04 and rCor a 2 as fusion proteins in E. coli from inclusion bodies resulted in approximately 10 mg pure protein per liter whereas rCor a 8 expression in yeast as nonfusion protein yielded 30 mg/L.     

X-ray Radioscopic Visualization of Bubbly Flows Injected Through a Top Submerged Lance into a Liquid Metal

Metallurgical and Materials Transactions B - We present an experimental study on the formation and behavior of a liquid metal bubbly flow arising from a downward gas injection through a top...     

Stakeholder engagement in water governance as social learning: lessons from practice

ABSTRACT

The OECD Principles on Water Governance set out various requirements for stakeholder engagement. Coupled with conceptualizations of social learning, this article asks how we define and enact stakeholder engagement and explores the actual practice of engagement of stakeholders in three fields of water governance. The results suggest that a key consideration is the purpose of the stakeholder engagement, requiring consideration of its ethics, process, roles and expected outcomes. While facilitators cannot be held accountable if stakeholder engagement ‘fails’ in terms of social learning, they are responsible for ensuring that the enabling conditions for social learning are met.     

From Facebook to the Neighbourhood: Infrastructuring of Hybrid Community Engagement

In recent years, social media have increased the resources that individuals and organizations are able to mobilize for the development of socially innovative practices. In this article, we engage with a naturally occurring development in a Trentinian neighbourhood to examine the cooperative interactions amongst members of a local community. The first author and local residents of the neighbourhood participated in online discussions, decision making, and physical activities that led to material changes in the area. The interventions are motivated by and based on the concept of Social Street that combines online interactions in a closed Facebook group with face-to-face meetings seeking to practically engage the collective in accomplishing certain immediate or ongoing needs. Over the course of two years, we studied this local instantiation of Social Street in Trento, Italy by way of an action-oriented (digital) ethnography. Through this work, we demonstrate how urban neighbourhoods might benefit from hybrid forms of community engagement that are enacted through a constant back and forth between online and face-to-face interactions. We further argue that the infrastructuring of local urban collectives should follow strategies that pay attention to the multiple issues in urban neighbourhoods and people’s attachments to them. Overall, the paper reflects upon the challenges and configurations of participation that this form of community-work entails.     

COMT genetic variation affects fear processing: Psychophysiological evidence.

Emotional dysregulation is a core characteristic of many psychiatric diseases, including the anxiety disorders. Although heritable influences account for a significant degree of variation in risk for such disorders, relatively few candidate susceptibility factors have been identified. A coding variant in one such gene, encoding the dopamine catabolic enzyme catechol-O-methyltransferase (COMT Val158Met), has previously been associated with anxiety and with anxiety-related temperament and altered neural responses to affective stimuli in healthy individuals. In 96 healthy women recruited from a sample of 800 participants according to genotype, the authors tested for an association between the DRD2/ANKK1 Taq Ia, the COMT Val158Met, and a psychophysiological measure of emotion processing, the acoustic affective startle reflex modulation (ASRM) paradigm, and found that COMT genotype significantly affected startle reflex modulation by aversive stimuli, with Met158 homozygotes exhibiting a markedly potentiated startle reflex compared with Val158 carriers. A trait measure of anxiety (Gray's Behavioral Inhibition System; J. A. Gray & N. McNaughton, 2000) was also associated with ASRM. The functional polymorphism in the dopamine D2 receptor (DRD2/ANKK1 Taq Ia) had no effect on startle modulation. The findings support prior genetic and neuroimaging associations of the COMT 158Met allele to affective psychopathology and alterations in neural systems for emotional arousal and regulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Nonlinear effects in LMS adaptive equalizers

An adaptive transversal equalizer based on the least-mean-square (LMS) algorithm, operating in an environment with a temporally correlated interference, can exhibit better steady-state mean-square-error (MSE) performance than the corresponding Wiener filter. This phenomenon is a result of the nonlinear nature of the LMS algorithm and is obscured by traditional analysis approaches that utilize the independence assumption (current filter weight vector assumed to be statistically independent of the current data vector). To analyze this equalizer problem, we use a transfer function approach to develop approximate analytical expressions of the LMS MSE for sinusoidal and autoregressive interference processes. We demonstrate that the degree to which LMS may outperform the corresponding Wiener filter is dependent on system parameters such as signal-to-noise ratio (SNR), signal-to-interference ratio (SIR), equalizer length, and the step-size parameter