The PecM protein is necessary for the DNA-binding capacity of the PecS repressor, one of the regulators of virulence-factor synthesis in Erwinia chrysanthemi

The pecS regulatory locus is responsible for the down-expression of many virulence genes in Erwinia chrysanthemi. This locus consists of two genes, pecS and pecM, divergently transcribed. Genetic evidence indicates that the PecM protein modulates the regulatory activity of PecS. Purification and characterization of PecS, expressed either from E. coli, from the wild-type E. chrysanthemi strain or from a pecM mutant, showed that the PecS protein produced in these three genetic backgrounds displays the same biochemical properties. Band-shift assay analysis with the three PecS isoforms confirmed the involvement of the PecM protein in modulating the PecS DNA-binding capacity. Moreover, determination of the Kd_app for operator regions of the PecS protein, produced either by the wild-type E. chrysanthemi or by E. coli, reveals similar affinities. Thus, in E. coli, there is likely to be at least one other PecM-like protein able to cross-react with the E. chrysanthemi PecS protein.     

Comparing the Effect of Uniaxial Cyclic Mechanical Stimulation and Chemical Factors on Myogenin and Myh2 Expression in Mouse Embryonic and Bone Marrow Derived Mesenchymal Stem Cells

Background: Environmental factors affect stem cell differentiation. In addition to chemical factors, mechanical signals have been suggested to enhance myogenic differentiation of stem cells. Therefore, this study was undertaken to illustrate and compare the effect of chemical and mechanical stimuli on Myogenin (MyoG) and Myosin heavy chani 2 (Myh2) expression of mouse bone marrowderived mesenchymal stem cells (BMSCs) and embryonic stem cells (ESCs). Methods: After isolation and expansion of BMSCs and generation of embryoid bodies and spontaneous differentiation of ESCs, cells were examined in 4 groups: (1) control group: untreated cells; (2) chemical group: cells incubated in myogenic medium (5-azacythidine and horse serum for BMSCs, dimethyl sulfoxide (DMSO) and horse serum for ESCs) for 5 days; (3) mechanical group: cells exposed to uniaxial cyclic strain (8%, 1 Hz, 24 h) and (4) chemical + mechanical group: cells incubated in myogenic medium for 4 days and then exposed to uniaxial cyclic strain. Real-time PCR was used to examine the expression of MyoG and Myh2 as specific myogenic markers. Results: suggested that mechanical loading, as a single factor, could elevate MyoG and Myh2 expression. Combining chemical with mechanical factor increases expression and there was no significant difference in MyoG expression of ESCs- and MSCs-chemical + mechanical groups; however, Myh2 expression was significantly higher in ESCs-mechanical group than that in the same group of MSCs.     

A multicomponent assembly pathway contributes to the formation of acentrosomal microtubule arrays in interphase Drosophila cells

In animal cells, centrosomes nucleate microtubules that form polarized arrays to organize the cytoplasm. Drosophila presents an interesting paradox however, as centrosome-deficient mutant animals develop into viable adults. To understand this discrepancy, we analyzed behaviors of centrosomes and microtubules in Drosophila cells, in culture and in vivo, using a combination of live-cell imaging, electron microscopy, and RNAi. The canonical model of the cycle of centrosome function in animal cells states that centrosomes act as microtubule-organizing centers throughout the cell cycle. Unexpectedly, we found that many Drosophila cell-types display an altered cycle, in which functional centrosomes are only present during cell division. On mitotic exit, centrosomes disassemble producing interphase cells containing centrioles that lack microtubule-nucleating activity. Furthermore, steady-state interphase microtubule levels are not changed by codepleting both gamma-tubulins. However, gamma-tubulin RNAi delays microtubule regrowth after depolymerization, suggesting that it may function partially redundantly with another pathway. Therefore, we examined additional microtubule nucleating factors and found that Mini-spindles, CLIP-190, EB1, or dynein RNAi also delayed microtubule regrowth; surprisingly, this was not further prolonged when we codepleted gamma-tubulins. Taken together, these results modify our view of the cycle of centrosome function and reveal a multi-component acentrosomal microtubule assembly pathway to establish interphase microtubule arrays in Drosophila.     

Does a short period of lower limb strength training improve performance in field-based tests of running and agility in young professional soccer players?

The present study assessed the effects of specific leg strength training (as part of a broader exercise program) on running speed and agility in young professional soccer players. Twenty-six male players (ages 17 to 19 years) were divided into 3 groups. The reference group (Re) performed individual technical work only, the coordination group (Co) performed a circuit designed to promote agility, coordination, and balance control (together with some technical work) and the Squat group (Sq) underwent 3 series of 3 squat repetitions (at 90% of the individual maximum value) and a sprint, before competition of the agility circuit and some technical work. These specific training programs were performed 5 times a week for 3 weeks. Before the experimental session and at the end of each week, all players were assessed using 4 types of tests, (agility, a shuttle test with changes of direction, and 2 sprints over 10 and 7.32 meters, respectively), with completion time being the only performance parameter recorded. Our results indicate that in the short sprints or shuttle sprint with changes in direction, lower limb strengthening did not improve performance. Performance improved in all 3 groups in the agility test but more so in the reference and coordination groups. It appears that soccer-specific training composed of exercise circuits specifically adapted to the different types of effort actually used in match play can enhance agility and coordination.     

Modulation of total ceramide and constituent ceramide species in the acutely and chronically hypoxic mouse heart at different ages

Ceramide has been implicated in regulatory processes vital for cell survival under different stressors, most notably hypoxia. Little has been done to investigate the contributions of the different ceramide species to the regulation of cell survival. This study aims to highlight the patterns of variation in total ceramide and its species in the growing and hypoxic mouse heart. Mus musculus mice were placed in a hypoxic environment at birth. Control animals remained in room air. The hearts were extracted at different time points: 1 day, 1 week, 4 weeks, and 8 weeks. The total ceramide content and the amounts of component species were assayed by a modified diacylglycerol kinase assay and high-performance liquid chromatography-tandem mass spectroscopy, respectively. Data was collected from both ventricles in hypoxic and control conditions. There was significant polycythemia in the hypoxic versus control animals with a nearly twofold increase in hematocrit levels. Hypoxic right ventricle (RV) mass significantly increased over that of controls at different age groups. When ceramide content was compared in the hypoxic versus control animals, there was a significant increase at day 1 and a significant decrease at week 4 in the left ventricle, whereas a significant decrease was found in the RV at 1 week, 4 weeks, and 8 weeks. There was also a differential involvement of the RV with regard to levels of N-palmitoyl-D-erythro-sphingosine (C16-Cer) and its synthetic precursor dihydro-N-palmitoyl-D-erythro-sphinganine (DHC-16-Cer). The decrease in C16-Cer observed in both hypoxic and control RV's over time was paralleled by a significant increase in DHC-16-Cer in hypoxic (142.1+/-15.0 pmol; p<0.05) but not control (52.8+/-4.0 pmol) RV's suggesting a role for DHC-16-Cer in the RV adaptive response to hypoxia. Another species, N-arachidoyl-D-erythro-sphingosine (C20-Cer), was specifically and significantly decreased in the hypoxic RV. These studies support the presence of distinct roles for different ceramide species and their precursors. A better assessment of cyanotic congenital heart disease in light of the mechanism and timing of cardiomyocyte death, will lead to punctual interventions and even novel cardioprotective strategies.     

The GacA global regulator is required for the appropriate expression of Erwinia chrysanthemi 3937 pathogenicity genes during plant infection

Pathogenicity of the phytopathogenic enterobacterium Erwinia chrysanthemi , the causal agent of soft rot disease on many plants, is a complex process involving several factors whose production is regulated by a complex, intertwined regulatory network. In this work we characterized the GacA regulator, member of the GacS–GacA two-component system, as a global regulator which is required for disease expression but not for bacterial multiplication in planta during the first stages of the plant infection. GacA was shown to control the expression of plant cell wall-degrading enzymes and hrp genes in vitro . Analysis of virulence gene expression during infection of Arabidopsis thaliana revealed a coordinated expression of these virulence genes at 12 h post infection and showed that GacA is required for the appropriate production of virulence factors in planta . GacA might partly act by negatively controlling the expression of the pecT gene encoding the global repressor PecT, indicating a hierarchy in the pathways involved in the E. chrysanthemi regulatory network.     

Lifetime prevalence of mental disorders in Lebanon: first onset, treatment, and exposure to war

Background

There are no published data on national lifetime prevalence and treatment of mental disorders in the Arab region. Furthermore, the effect of war on first onset of disorders has not been addressed previously on a national level, especially in the Arab region. Thus, the current study aims at investigating the lifetime prevalence, treatment, age of onset of mental disorders, and their relationship to war in Lebanon.

Methods and Findings

The Lebanese Evaluation of the Burden of Ailments and Needs Of the Nation study was carried out on a nationally representative sample of the Lebanese population (n = 2,857 adults). Respondents were interviewed using the fully structured WHO Composite International Diagnostic Interview 3.0. Lifetime prevalence of any Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) disorder was 25.8%. Anxiety (16.7%) and mood (12.6%) were more common than impulse control (4.4%) and substance (2.2%) disorders. Only a minority of people with any mental disorder ever received professional treatment, with substantial delays (6 to 28 y) between the onset of disorders and onset of treatment. War exposure increased the risk of first onset of anxiety (odds ratio [OR] 5.92, 95% confidence interval [CI] 2.5–14.1), mood (OR 3.32, 95% CI 2.0–5.6), and impulse control disorders (OR 12.72, 95% CI 4.5–35.7).

Conclusions

About one-fourth of the sample (25.8%) met criteria for at least one of the DSM-IV disorders at some point in their lives. There is a substantial unmet need for early identification and treatment. Exposure to war events increases the odds of first onset of mental disorders.     

Bone marrow-derived endothelial progenitor cells contribute to the angiogenic switch in tumor growth and metastatic progression

Emerging evidence indicates that bone marrow (BM)-derived endothelial progenitor cells (EPCs) contribute to angiogenesis-mediated growth of certain tumors in mice and human. EPCs regulate the angiogenic switch via paracrine secretion of proangiogenic growth factors and by direct luminal incorporation into sprouting nascent vessels. While the contributions of EPCs to neovessel formation in spontaneous and transplanted tumors and to the metastatic transition have been reported to be relatively low, remarkably, specific EPC ablation in vivo has resulted in severe angiogenesis inhibition and impaired primary and metastatic tumor growth. The existence of a BM reservoir of EPCs, and the selective involvement of EPCs in neovascularization, have attracted considerable interest because these cells represent novel target for therapeutic intervention. In addition, EPCs are also being used as pharmacodynamic surrogate markers for monitoring cancer progression, as well as for optimizing efficacy of anti-angiogenic therapies in the clinic. This review will focus primarily on recent advances and emerging concepts in the field of EPC biology and discuss ongoing debates involving the role of EPCs in tumor neovascularization. For detailed information on the in vitro characterization of EPCs contribution to non-tumor pathologies, the reader is directed towards several excellent reviews and publications [F. Bertolini, Y. Shaked, P. Mancuso and R.S. Kerbel, Nat. Rev., Cancer 6 (2006) 835–845. [1]] [J.M. Hill, T. Finkel and A.A. Quyyumi, Vox Sang. 87 Suppl 2 (2004) 31–37. [2]] [A.Y. Khakoo and T. Finkel, Annu. Rev. Med. 56 (2005) 79–101. [3]] [H.G. Kopp, C.A. Ramos and S. Rafii, Curr. Opin. Hematol. 13 (2006) 175–181. [4]; K.K. Hirschi, D.A. Ingram and M.C. Yoder, Arterioscler. Thromb. Vasc. Biol. 28 (2008) 1584–1595. [5]; F. Timmermans, J. Plum, M.C. Yoder, D.A. Ingram, B. Vandekerckhove and J. Case, J. Cell. Mol. Med. 13 (2009) 87–102. [6]] and reviews by Bertolini, Voest and Yoder in this issue.     

Association of sugar content QTL and PQL with physiological traits relevant to frost damage resistance in pea under field and controlled conditions

To increase yield in pea (Pisum sativum L.), autumn sowing would be preferable. Hence, frost tolerance of pea became a major trait of interest for breeders. In order to better understand the cold acclimation in pea, Champagne a frost tolerant line and Terese, a frost sensitive line, and their recombinant inbred lines (RIL) were studied. RIL frost tolerance was evaluated by a frost damage scale under field as well as controlled conditions. A quantitative trait loci (QTL) approach was used to identify chromosomal regions linked to frost tolerance. The detected QTL explained from 6.5 to 46.5% of the phenotypic variance. Amongst them, those located on linkage groups 5 and 6 were consistent with over all experiments, in field as well as in controlled environments. In order to improve the understanding of the frost tolerance mechanisms, several cold acclimation key characters such as concentration of sugars, electrolyte leakage, osmotic pressure, and activity of RuBisCO were assessed. Some of these physiological QTL colocalised with QTL for frost damage, in particular two raffinose QTL on LG5 and LG6 and one RuBisCO activity QTL on LG6, explaining 8.8 to 27.0% of the phenotypic variance. In addition, protein quantitative loci were mapped; some of them colocalised with frost damage and physiological QTL on LG5 and LG6, explaining 16.0–43.6% of the phenotypic variance. Raffinose metabolism and RuBisCO activity and its effect on photosynthesis might play a major role in cold acclimation of pea. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.