RecA Protein Plays a Role in the Chemotactic Response and Chemoreceptor Clustering of Salmonella enterica

The RecA protein is the main bacterial recombinase and the activator of the SOS system. In Escherichia coli and Salmonella enterica sv. Typhimurium, RecA is also essential for swarming, a flagellar-driven surface translocation mechanism widespread among bacteria. In this work, the direct interaction between RecA and the CheW coupling protein was confirmed, and the motility and chemotactic phenotype of a S. Typhimurium ΔrecA mutant was characterized through microfluidics, optical trapping, and quantitative capillary assays. The results demonstrate the tight association of RecA with the chemotaxis pathway and also its involvement in polar chemoreceptor cluster formation. RecA is therefore necessary for standard flagellar rotation switching, implying its essential role not only in swarming motility but also in the normal chemotactic response of S. Typhimurium.National Institutes of Health (U.S.) (Grant 1R01GM100473

Brote de histoplasmosis pulmonar relacionado con presencia de murciélagos en la provincia de Ciego de Ávila, Cuba

Se describe un brote de histoplasmosis pulmonar que afectó a cinco personas en un centro de trabajo de la provincia de Ciego de Avila (Cuba), relacionado con la presencia de murciélagos en el hábitat. El período de incubación de los enfermos osciló de 3 a 14 días. Inicialmente se planteó el diagnóstico de histoplasmosis a un paciente. El cuadro clínico fue leve en 4 casos y moderado en un caso, predominando la tos no productiva. El enfermo que presentó disnea y dolor toráxico tuvo la mayor exposición. La desaparición de los síntomas fluctuó entre 4 y 26 días

Withaferin A induces apoptosis in human melanoma cells through generation of reactive oxygen species and down-regulation of Bcl-2

A high resistance and heterogeneous response to conventional anti-cancer chemotherapies characterize malignant cutaneous melanoma, the most aggressive and deadly form of skin cancer. Withaferin A (WFA), a withanolide derived from the medicinal plant Withania somnifera, has been reported for its anti-tumorigenic activity against various cancer cells. For the first time, we examined the death-inducing potential of WFA against a panel of four different human melanoma cells and investigated the cellular mechanisms involved. WFA induces apoptotic cell death with various IC50 ranging from 1.8 to 6.1 lM. The susceptibility of cells toward WFA-induced apoptosis correlated with low Bcl-2/Bax and Bcl-2/Bim ratios. In all cell lines, the apoptotic process triggered by WFA involves the mitochondrial pathway and was associated with Bcl-2 down regulation, Bax mitochondrial translocation, cytochrome c release into the cytosol, transmembrane potential (DWm) dissipation, caspase 9 and caspase 3 activation and DNA fragmentation. WFA cytotoxicity requires early reactive oxygen species (ROS) production and glutathione depletion, the inhibition of ROS increase by the antioxidant N-acetylcysteine resulting in complete suppression of mitochondrial and nuclear events. Altogether, these results support the therapeutic potential of WFA against human melanoma. © Springer Science+Business Media, LLC 2011

RecA protein plays a role in the chemotactic response and chemoreceptor clustering of Salmonella enterica

The RecA protein is the main bacterial recombinase and the activator of the SOS system. In Escherichia coli and Salmonella enterica sv. Typhimurium, RecA is also essential for swarming, a flagellar-driven surface translocation mechanism widespread among bacteria. In this work, the direct interaction between RecA and the CheW coupling protein was confirmed, and the motility and chemotactic phenotype of a S. Typhimurium DrecA mutant was characterized through microfluidics, optical trapping, and quantitative capillary assays. The results demonstrate the tight association of RecA with the chemotaxis pathway and also its involvement in polar chemoreceptor cluster formation. RecA is therefore necessary for standard flagellar rotation switching, implying its essential role not only in swarming motility but also in the normal chemotactic response of S. Typhimurium

The fourth isoform of the adenine nucleotide translocator inhibits mitochondrial apoptosis in cancer cells

10.1016/j.biocel.2009.12.024International Journal of Biochemistry and Cell Biology425623-62

The chemotactic response of the <i>S</i>. Typhimurium Δ<i>recA</i> mutant is impaired.

<p>The chemotactic responses of <i>S</i>. Typhimurium wild-type (WT), Δ<i>recA</i>, Δ<i>recA</i> complemented (Δ<i>recA</i> pUA1109), and Δ<i>cheB</i> (tumbling) cells were assessed using Adler's capillary assay <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0105578#pone.0105578-Adler1" target="_blank">[30]</a> with the modifications described in Materials and Methods. Values are expressed as the number of viable cells (in cfu/ml) in a capillary tube containing either 10 mM aspartate (+) or tethering buffer alone (−). The results are the mean of five independent experiments of three capillaries each. Error bars indicate the standard deviation. ***p<0.001 and *p<0.05 as determined by two-way ANOVA with Bonferroni correction.</p

Bacterial strains and plasmids used in this work.

<p>Bacterial strains and plasmids used in this work.</p