Crystal Structure of H227A Mutant of Arginine Kinase in Daphnia magna Suggests the Importance of Its Stability.

Arginine kinase (AK) plays a crucial role in the survival of Daphnia magna, a water flea and a common planktonic invertebrate sensitive to water pollution, owing to the production of bioenergy. AK from D. magna (DmAK) has four highly conserved histidine residues, namely, H90, H227, H284, and H315 in the amino acid sequence. In contrast to DmAK WT (wild type), the enzyme activity of the H227A mutant decreases by 18%. To identify the structure-function relationship of this H227A mutant enzyme, the crystal 3D X-ray structure has been determined and an unfolding assay using anilino-1-naphthalenesulfonic acid (ANS) fluorescence has been undertaken. The results revealed that when compared to the DmAK WT, the hydrogen bonding between H227 and A135 was broken in the H227A crystal structure. This suggests that H227 residue, closed to the arginine binding site, plays an important role in maintaining the structural stability and maximizing the enzyme activity through hydrogen bonding with the backbone oxygen of A135.

The effects of the activation of hostile and non-hostile schemas on intent attribution processes in non-aggressive individuals: An ERP study.

We investigated the influences of hostile and non-hostile schemas activations in non-aggressive individuals on their intent attribution processes in various social contexts. 38 non-aggressive participants were randomly assigned to one of two groups, one primed with negative words, to be conditioned as temporarily hostile (TH), and the other with positive words, be conditioned as temporarily non-hostile (TNH). They were asked to read social scenarios composed of positive or negative behaviors of others whose intentions are ambiguous followed by a disambiguation of others' real intentions (hostile vs non-hostile) behind their behaviors. Neural activity related to spontaneous intent attribution processes was measured using electroencephalography (EEG). The results showed that when non-hostile intentions were revealed following ambiguous-negative behaviors of others, the N400 effect was observed only in the TH group. Similarly, when hostile intentions were revealed following ambiguous-positive behaviors of others, the N400 effect was observed only in the TNH group. In other words, non-aggressive individuals were led to attribute either hostile or non-hostile intentions to the same ambiguous behaviors of others depending on which concepts or thoughts (hostile vs non hostile) were activated and accessible in memory by priming at the time of social interactions.

The Modulating Role of Self-Referential Stimuli and Processes in the Effect of Stress and Negative Emotion on Inhibition Processes in Borderline Personality Disorder: Proposition of a Model to Integrate the Self-Concept and Inhibition Processes.

Impulsivity is an important clinical and diagnostic feature of borderline personality disorder (BPD). Even though it has been reported that BPD individuals' inhibition performance is significantly reduced in the context of negative emotion or stress, this literature shows mixed results, raising questions about the possible role played by other factors. Winter (2016) proposed that negative emotion stimuli can be more disruptive for BPD individuals' attention control performance because they induce higher distractibility self-referential processes. This article aimed to systematically review the literature regarding the effect of stress and negative emotions on three main inhibition processes-prepotent response inhibition, resistance to distractor interference, and resistance to proactive interference-in BPD and to verify the putative modulating role of self-referential stimuli and processes on these inhibition processes. All English and French experimental studies published until August 2018 were searched in PsychINFO and PubMED databases. The following keywords were used: "borderline* AND inhibit* OR interference* OR forget* OR task* AND emotion* OR stress* OR affect*". A total of 1215 articles were included in the study. After full text revision, twenty-six papers were selected for review. The results of this review indicate that when stimuli or procedures involve self-reference stimuli or processes, BPD individuals' performance seems to be more disrupted in all three inhibition processes. A model based on Winter's and Kernberg's models is proposed with the aim of integrating the self-concept with inhibition processes in BPD.