Chronic lung infection is the major cause of morbidity and premature mortality in cystic fibrosis (CF) patients. Bacteria of the Burkholderia cepacia complex are the most threatening pathogens in CF, and a better understanding of how these bacteria adapt to the CF airway environment and resist the host defense mechanisms and therapeutically administered antibiotics is crucial. To provide clues to the adaptive strategies adopted by Burkholderia cenocepacia during long-term colonization, we carried out a phenotypic assessment of 11 clonal variants obtained at the major Portuguese CF Center in Lisbon from sputa of the same CF patient during 3.5 years of colonization of the lungs, until the patient's death with cepacia syndrome. Phenotypic characterization included susceptibility assays against different classes of antimicrobials and characterization of cell motility, cell hydrophobicity and zeta potential, colony and cell morphology, fatty acid composition, growth under iron limitation/load conditions, exopolysaccharide production, and size of the biofilms formed. The results suggest the occurrence of clonal expansion during long-term colonization. For a number of the characteristics tested, no isolation time-dependent consistent alteration pattern could be identified. However, the values for antimicrobial susceptibility and swarming motility for the first B. cenocepacia isolate, thought to have initiated the infection, were consistently above those for the clonal variants obtained during the course of infection, and the opposite was found for the zeta potential. The adaptive strategy for long-term colonization, described here for the first time, involved the alteration of membrane fatty acid composition, in particular a reduction of the degree of fatty acid saturation, in the B. cenocepacia variants retrieved, along with the deterioration of pulmonary function and severe oxygen limitation.

Pulmonary colonization of cystic fibrosis (CF) patients with Burkholderia cenocepacia or other bacteria of the Burkholderia cepacia complex (Bcc) is associated with worse prognosis and increased risk of death. During colonization, the bacteria may evolve under the stressing selection pressures exerted in the CF lung, in particular, those resulting from challenges of the host immune defenses, antimicrobial therapy, nutrient availability and oxygen limitation. Understanding the adaptive mechanisms that promote successful colonization and long-term survival of B. cenocepacia in the CF lung is essential for an improved therapeutic outcome of chronic infections. To get mechanistic insights into these adaptive strategies a transcriptomic analysis, based on DNA microarrays, was explored in this study. The genomic expression levels in two clonal variants isolated during long-term colonization of a CF patient who died from the cepacia syndrome were compared. One of the isolates examined, IST439, is the first B. cenocepacia isolate retrieved from the patient and the other isolate, IST4113, was obtained three years later and is more resistant to different classes of antimicrobials. Approximately 1000 genes were found to be differently expressed in the two clonal variants reflecting a marked reprogramming of genomic expression. The up-regulated genes in IST4113 include those involved in translation, iron uptake (in particular, in ornibactin biosynthesis), efflux of drugs and in adhesion to epithelial lung tissue and to mucin. Alterations related with adaptation to the nutritional environment of the CF lung and to an oxygen-limited environment are also suggested to be a key feature of transcriptional reprogramming occurring during long-term colonization, antibiotic therapy and the progression of the disease.

Chronic respiratory infections caused by Burkholderia cenocepacia in patients with cystic fibrosis (CF) are characterized by low responsiveness to antibiotic therapy and, in general, to a more rapid decline of lung function. To get clues into the molecular mechanisms underlying the adaptive strategies employed to deal with the stressing conditions of the CF lung including antibiotic therapy, quantitative proteomics (2-D DIGE) was used to compare the expression programs of two clonal isolates retrieved from a chronically infected CF patient. Isolate IST439 was the first bacterium recovered while the clonal variant IST4113 was obtained after 3 years of persistent infection and intravenous therapy with ceftazidime/gentamicin. This isolate exhibits higher resistance levels towards different classes of antimicrobials. Proteins of the functional categories Energy metabolism, Translation, Nucleotide synthesis, Protein folding and stabilization are more abundant in IST4113, compared with IST439, suggesting an increased protein synthesis, DNA repair and stress resistance in IST4113. The level of proteins involved in peptidoglycan, membrane lipids and lipopolysaccharide synthesis is also altered and proteins involved in iron binding and transport are more abundant in IST4113. The quantitative comparison of the two proteomes suggests a genetic adaptation leading to increased antimicrobial resistance and bacterial persistence in the CF airways.

Human mesenchymal stem cells (MSC) have been on the focus of intense clinical-oriented research due to their multilineage differentiation potential and immunomodulatory properties. However, to reach the clinically meaningful cell numbers for cellular therapy and tissue engineering applications, MSC ex-vivo expansion is mandatory but sequential cell passaging results in loss of proliferative, clonogenic and differentiation potential. To get clues into the molecular mechanisms underlying cellular senescence resulting from extended ex-vivo cultivation of bone marrow (BM) MSC, we explored a two-dimensional gel electrophoresis (2-DE) based quantitative proteomics to compare the expression programs of Passage 3 cells (P3), commonly used in clinical studies with expanded MSC, and Passage 7 (P7) cells, which already demonstrated significant signs of culture-induced senescence. Proteins of the functional categories “Structural components and cellular cytoskeleton” and “Folding and stress response proteins” are less abundant in P7 cells, compared to P3, while proteins involved in “Energy metabolism”, “Cell cycle regulation and aging” and “Apoptosis” are more abundant. The large number of multiple size and charge isoforms with an altered content that were identified in this study in P7 versus P3, namely the cytoskeleton components β-actin (7 forms) and vimentin (24 forms), also emphasizes the importance of post-transcriptional modification upon long-term cultivation. The differential protein expression registered suggests that cellular senescence occurring during ex-vivo expansion of BM MSC is associated with the impairment of cytoskeleton remodeling and/or organization and the repair of damaged proteins resulting from cell exposure to culture stress. The genome-wide expression approach used in this study has proven useful for getting mechanistic insights into the observed decrease on the proliferative and clonogenic potential of P7 versus P3 cells and paves the way to set up a proteome profiling strategy for quality control to assure safe and clinically effective expanded MSC.

Respiratory infections with Burkholderia cepacia complex (Bcc) bacteria in cystic fibrosis (CF) are associated with a worse prognosis and increased risk of death. In this work, we assessed the virulence potential of three B. cenocepacia clonal isolates obtained from a CF patient between the onset of infection (isolate IST439) and before death with cepacia syndrome 3.5 years later (isolate IST4113 followed by IST4134), based on their ability to invade epithelial cells and compromise epithelial monolayer integrity. The two clonal isolates retrieved during late-stage disease were significantly more virulent than IST439. Proteomic profiling by 2-D DIGE of the last isolate recovered before the patient’s death, IST4134, and clonal isolate IST439, was performed and compared with a prior analysis of IST4113 vs. IST439. The cytoplasmic and membrane-associated enriched fractions were examined and 52 proteins were found to be similarly altered in the two last isolates compared with IST439. These proteins are involved in metabolic functions, nucleotide synthesis, translation and protein folding, cell envelope biogenesis and iron homeostasis. Results are suggestive of the important role played by metabolic reprogramming in the virulence potential and persistence of B. cenocepacia, in particular regarding bacterial adaptation to microaerophilic conditions. Also, the content of the virulence determinant AidA was higher in the last 2 isolates. Significant levels of siderophores were found to be secreted by the three clonal isolates in an iron-depleted environment, but the two late isolates were more tolerant to low iron concentrations than IST439, consistent with the relative abundance of proteins involved in iron uptake.

Psychological interest in Meritocracy as an important social norm regulating most of the western democratic societies has significantly increased over the years. However, the way Meritocracy has been conceptualized and operationalized in experimental studies has advanced in significant ways. As a result, a variety of paradigms arose to understand the social consequences of Meritocracy for intergroup relations; in particular, to understand the adverse consequences of Meritocracy for disadvantaged group members. The present research seeks to understand whether there is strong support for the idea that (manipulated) Meritocracy disproportionally affects members of low status groups, and also to understand which specific components of this norm have been successfully manipulated and to what consequences. And this is particularly important given the recent call for greater transparency in how the success of experimental manipulations is reported. Thus, we carried out a systematic review examining the content of different prime tasks, summarizing prime manipulation checks' effectiveness, and analyzing whether priming Meritocracy leads to less favorable orientations toward low status groups. Results across 33 studies revealed that despite the existing differences in the components highlighted, the salience of any of the Meritocracy dimensions facilitates the use of internal causal attributions, negative evaluations and stereotyping toward low status groups, affecting negatively decisions involving low-status group members, particularly in specific domains, as organizational contexts. These results carry both practical and theoretical implications for future research on the role of Meritocracy in intergroup settings.

Objective: The present experiment analyzed the effects of playing a violent video game on player’s sensitivity to victimized people by measuring the involuntary pupil dilation responses (PDRs) during a passive picture viewing paradigm and examining the mediating role of PDR on aggression. Method: Participants (N = 135) were randomly assigned to play a violent video game or a nonviolent video game. The participants’ PDRs were then recorded while they were exposed to pictures of alleged victims of violence displayed in negative, neutral, and positive contexts. A competitive reaction time task was also used to measure aggression. Results: Participants in the violent game condition demonstrated both a lower PDR to the victims of violence in a negative circumstances and greater aggression than participants in the nonviolent game condition. Lower PDR to victims displayed in negative context mediated the relationship between violent game play and aggression. Conclusion: The negative effects of playing violent games are a societal concern. Our results indicate that a single violent gaming session can reduce the player’s involuntary PDRs to pictures of victimized people in negative context and increase participant aggression, a new relevant finding that should encourage further research in this area.

This article was originally published in Proteomics 2011, 11, 1313–1328, DOI