Tolerance of β-diketone hydrolases as representatives of the crotonase superfamily towards organic solvents

Crotonase superfamily enzymes catalyze a wide variety of reactions, including hydrolytic C–C bond cleavage in symmetrical β‐diketones by 6‐oxo camphor hydrolase (OCH) from Rhodococcus sp. The organic solvent tolerance and temperature stability of OCH and its structurally related ortholog Anabaena β‐diketone hydrolase have been investigated. Both enzymes showed excellent tolerance toward organic solvents; for instance, even in the presence of 80% (v/v) THF or dioxane, OCH was still active. In most solvent mixtures, except methanol, the stereospecificity was conserved (>99% e.e. of product), hence neither the type of solvent nor its concentration appeared to have an effect on the stereoselectivity of the enzyme. Attempts to correlate the observed activities with log P, functional solvent group or denaturing capacity (DC) of the solvent were only successful in the case of DC for water miscible solvents. This study represents the first investigation of organic solvent stability for members of the crotonase superfamily. Biotechnol. Bioeng. 2011;108: 2815–2822. © 2011 Wiley Periodicals, Inc.     

Negative Evaluation Bias for Positive Self-Referential Information in Borderline Personality Disorder

Previous research has suggested that patients meeting criteria for borderline personality disorder (BPD) display altered self-related information processing. However, experimental studies on dysfunctional self-referential information processing in BPD are rare. In this study, BPD patients (N = 30) and healthy control participants (N = 30) judged positive, neutral, and negative words in terms of emotional valence. Referential processing was manipulated by a preceding self-referential pronoun, an other-referential pronoun, or no referential context. Subsequently, patients and participants completed a free recall and recognition task. BPD patients judged positive and neutral words as more negative than healthy control participants when the words had self-reference or no reference. In BPD patients, these biases were significantly correlated with self-reported attributional style, particularly for negative events, but unrelated to measures of depressive mood. However, BPD patients did not differ from healthy control participants in a subsequent free recall task and a recognition task. Our findings point to a negative evaluation bias for positive, self-referential information in BPD. This bias did not affect the storage of information in memory, but may be related to self-attributions of negative events in everyday life in BPD.     

Incidence of virulence-encoding genes among enteric Escherichia coli strains isolated from healthy subjects

Escherichia coli, heterogeneous species consisting of commensal and pathogenic strains, is causing a broad spectrum of intestinal and extra intestinal diseases, ranging from asymptomatic infections to septicaemia, according to its capacity to produce different virulence factors. The incidence of different virulence-associated genes among the strains isolated from healthy subjects, taking into account that the human gastrointestinal tract is considered an important source for spreading E. coli strains, was evaluated. A total of 241 E. coli strains isolated from 41 healthy subjects, working in the food chain and coming to the laboratory for periodical medical control, were investigated for harbouring patogenicity factors--encoding genes. Extra intestinal virulence-associated genes, pap, sfa/foc, afa, hly, cnf and intestinal ones eaea, bfp, agg, It, st, vtx1 (stx1), vtx2 (stx2) and ipaH, were targeted by PCR using cellular lysate for total DNA. Genes encoding for adherence were the most prevalent. A number of 67 strains (27.80%) were positive for pap genes and 34 strains (14.11%) presented PCR positive results when afa genes were targeted, but sfa/foc genes were identified in only 10 strains (4.15%). Genes encoding for toxigenesis were less prevalent. A total of 9 strains amplified hly genes, 2.49% were positive for cnf genes and only 2 strains presented vtx1(stx1) gene. The results are in concordance with those which demonstrate that healthy subjects carrying strains possessing virulence-encoding genes could represent a reservoir for environmental circulation of such strains, considered life-threatening when a receptive host is encountered.     

Ergosterol levels in two l-methionine-enriched mutants of the methylotrophic yeast Candida boidinii ICCF26

Two L-methionine-enriched mutants, SN-78 and SE-57, were isolated in a sulphur-deficient medium from the methylotrophic yeast Candida boidinii ICCF26. No significant differences were detected between the L-cysteine pools of the mutants and the wild-type. In mutant strain SE-57, S-adenosylmethionine and ergosterol levels were higher than in the wild-type strain, while in the other mutant, SN-78, the levels were lower. The evidence presented would suggest that, in both the mutants and the wild-type used in this study, S-adenosylmethionine was of key importance for the accumulation of L-methionine and ergosterol.     

Selective Interaction Model and Photoreceptor Cell Membrane

A mathematical model is proposed in order to describe, from the thermodynamic point of view, the changes in the photoreceptorcell membrane induced by light stimuli. The phenomenologicalbackground is the increase of the fly microvillar membrane ionicconductivity as a consequence of Ca^++-Na⁺ affinity modification under light action. On the basis of the analogywith the model of protein interaction in mixed solvents, themodel is focused on the selective interaction between ionchannels gates and two ionic ligands. Three possible theoretical cases are examined.     

Dihydrotestosterone potentiates insulin to up-regulate prokineticin-1 in decidualizing human endometrial stromal cells

Prokineticin 1 (PROK1) is a key regulator of embryo implantation and placentation, and its dysregulation is associated with pregnancy complications, such as pre-eclampsia and foetal growth restriction. We have previously shown that insulin strongly enhances the expression of PROK1 in human decidualizing stromal cells. Here, we demonstrate that dihydrotestosterone (DHT), but not testosterone, potentiates insulin to up-regulate PROK1 in these cells. However, the androgens alone do not influence the expression of PROK1. Our findings suggest that insulin and androgens both are involved in the regulation of PROK1 that could have implications for normal and pathological pregnancies.     

Proteomic Analysis of the Maternal Preoptic Area in Rats

The behavior of female rats changes profoundly as they become mothers. The brain region that plays a central role in this regulation is the preoptic area, and lesions in this area eliminates maternal behaviors in rodents. The molecular background of the behavioral changes has not been established yet; therefore, in the present study, we applied proteomics to compare protein level changes associated with maternal care in the rat preoptic area. Using 2-dimensional fluorescence gel electrophoresis followed by identification of altered spots with mass spectrometry, 12 proteins were found to be significantly increased, and 6 proteins showed a significantly reduced level in mothers. These results show some similarities with a previous proteomics study of the maternal medial prefrontal cortex and genomics approaches applied to the preoptic area. Gene ontological analysis suggested that most altered proteins are involved in glucose metabolism and neuroplasticity. These proteins may support the maintenance of increased neuronal activity in the preoptic area, and morphological changes in preoptic neuronal circuits are known to take place in mothers. An increase in the level of alpha-crystallin B chain (Cryab) was confirmed by Western blotting. This small heat shock protein may also contribute to maintaining the increased activity of preoptic neurons by stabilizing protein structures. Common regulator and target analysis of the altered proteins suggested a role of prolactin in the molecular changes in the preoptic area. These results first identified the protein level changes in the maternal preoptic area. The altered proteins contribute to the maintenance of maternal behaviors and may also be relevant to postpartum depression, which can occur as a molecular level maladaptation to motherhood.

     

Androgen receptor drives cellular senescence

The accepted androgen receptor (AR) role is to promote proliferation and survival of prostate epithelium and thus prostate cancer progression. While growth-inhibitory, tumor-suppressive AR effects have also been documented, the underlying mechanisms are poorly understood. Here, we for the first time link AR anti-cancer action with cell senescence in vitro and in vivo. First, AR-driven senescence was p53-independent. Instead, AR induced p21, which subsequently reduced ΔN isoform of p63. Second, AR activation increased reactive oxygen species (ROS) and thereby suppressed Rb phosphorylation. Both pathways were critical for senescence as was proven by p21 and Rb knock-down and by quenching ROS with N-Acetyl cysteine and p63 silencing also mimicked AR-induced senescence. The two pathways engaged in a cross-talk, likely via PML tumor suppressor, whose localization to senescence-associated chromatin foci was increased by AR activation. All these pathways contributed to growth arrest, which resolved in senescence due to concomitant lack of p53 and high mTOR activity. This is the first demonstration of senescence response caused by a nuclear hormone receptor.