Genetic regulation of the ompX porin of Salmonella Typhimurium in response to hydrogen peroxide stress.

BACKGROUND: Salmonella Typhimurium is a Gram-negative pathogen that causes a systemic disease in mice resembling typhoid fever. During its infective cycle, S. Typhimurium is phagocytized by macrophages and proliferates inside a Salmonella-containing vacuole where Salmonella is exposed and survives oxidative stress induced by H2O2 through modulation of gene expression. After exposure of Salmonella to H2O2, the expression of the porin-encoding gene ompX increases, as previously shown by microarray analysis. Expression of ompX mRNA is regulated at a post-transcriptional level by MicA and CyaR sRNAs in aerobiosis. In addition, sequence analysis predicts a site for OxyS sRNA in ompX mRNA. RESULTS: In this work we sought to evaluate the transcriptional and post-transcriptional regulation of ompX under H2O2 stress. We demonstrate that ompX expression is induced at the transcriptional level in S. Typhimurium under such conditions. Unexpectedly, an increase in ompX gene transcript and promoter activity after challenges with H2O2 does not translate into increased protein levels in the wild-type strain, suggesting that ompX mRNA is also regulated at a post-transcriptional level, at least under oxidative stress. In silico gene sequence analysis predicted that sRNAs CyaR, MicA, and OxyS could regulate ompX mRNA levels. Using rifampicin to inhibit mRNA expression, we show that the sRNAs (MicA, CyaR and OxyS) and the sRNA:mRNA chaperone Hfq positively modulate ompX mRNA levels under H2O2-induced stress in Salmonella during the exponential growth phase in Lennox broth. CONCLUSIONS: Our results demonstrate that ompX mRNA is regulated in response to H2O2 by the sRNAs CyaR, MicA and OxyS is Salmonella Typhimurium.

Genetic regulation of the ompX porin of Salmonella Typhimurium in response to hydrogen peroxide stress

BACKGROUND: Salmonella Typhimurium is a Gram negative pathogen that causes a systemic disease in mice resembling typhoid fever. During its infective cycle, S. Typhimurium is phagocytized by macrophages and proliferates inside a Salmonella containing vacuole where Salmonella is exposed and survives oxidative stress induced by H2O2 through modulation of gene expression. After exposure of Salmonella to H2O2, the expression of the porin encoding gene ompX increases, as previously shown by microarray analysis. Expression of ompX mRNA is regulated at a post transcriptional level by MicA and CyaR sRNAs in aerobiosis. In addition, sequence analysis predicts a site for OxyS sRNA in ompX mRNA. RESULTS: In this work we sought to evaluate the transcriptional and post transcriptional regulation of ompX under H2O2 stress. We demonstrate that ompX expression is induced at the transcriptional level in S . Typhimurium under such conditions. Unexpectedly, an increase in ompX gene transcript and promoter activity after challenges with H2O2 does not translate into increased protein levels in the wild type strain, suggesting that ompX mRNA is also regulated at a post transcriptional level, at least under oxidative stress. In silico gene sequence analysis predicted that sRNAs CyaR, MicA, and OxyS could regulate ompX mRNA levels. Using rifampicin to inhibit mRNA expression, we show that the sRNAs (MicA, CyaR and OxyS) and the sRNA:mRNA chaperone Hfq positively modulate ompX mRNA levels under H2O2 induced stress in Salmonella during the exponential growth phase in Lennox broth. CONCLUSIONS: Our results demonstrate that ompX mRNA is regulated in response to H2O2 by the sRNAs CyaR, MicA and OxyS is Salmonella Typhimurium.

Three-dimensional microscale hanging drop arrays with geometric control for drug screening and live tissue imaging.

Existing three-dimensional (3D) culture techniques are limited by trade-offs between throughput, capacity for high-resolution imaging in living state, and geometric control. Here, we introduce a modular microscale hanging drop culture where simple design elements allow high replicates for drug screening, direct on-chip real-time or high-resolution confocal microscopy, and geometric control in 3D. Thousands of spheroids can be formed on our microchip in a single step and without any selective pressure from specific matrices. Microchip cultures from human LN229 glioblastoma and patient-derived mouse xenograft cells retained genomic alterations of originating tumors based on mate pair sequencing. We measured response to drugs over time with real-time microscopy on-chip. Last, by engineering droplets to form predetermined geometric shapes, we were able to manipulate the geometry of cultured cell masses. These outcomes can enable broad applications in advancing personalized medicine for cancer and drug discovery, tissue engineering, and stem cell research.

Correlated flickering of erythrocytes membrane observed with dual time resolved membrane fluctuation spectroscopy under different D-glucose concentrations.

A correlated human red blood cell membrane fluctuation dependent on D-glucose concentration was found with dual time resolved membrane fluctuation spectroscopy (D-TRMFS). This new technique is a modified version of the dual optical tweezers method that has been adapted to measure the mechanical properties of red blood cells (RBCs) at distant membrane points simultaneously, enabling correlation analysis. Mechanical parameters under different D-glucose concentrations were obtained from direct membrane flickering measurements, complemented with membrane fluidity measurements using Laurdan Generalized Polarization (GP) Microscopy. Our results show an increase in the fluctuation amplitude of the lipid bilayer, and a decline in tension value, bending modulus and fluidity as D-glucose concentration increases. Metabolic mechanisms are proposed as explanations for the results.

Recent increase of ulcerative lesions caused by Anisakis spp. in cetaceans from the north-east Atlantic.

Species of Anisakis typically infect the stomach of cetaceans worldwide, often causing ulcerative lesions that may compromise the host's health. These nematodes also cause anisakiasis or allergic reactions in humans. To assess the risks of this emerging zoonosis, data on long-term changes in Anisakis infections in cetaceans are necessary. Here, we compare the prevalence and severity of ulcerative lesions caused by Anisakis spp. in five cetacean species stranded along the north-west Spanish coast in 2017-2018 with published data from 1991-1996. Open ulcers were found in 32/43 short-beaked common dolphins, Delphinus delphis; 3/5 striped dolphins, Stenella coeruleoalba; 1/7 bottlenose dolphins, Tursiops truncatus; and 1/3 harbour porpoises, Phocoena phocoena meridionalis; a single individual of long-finned pilot whale, Globicephala melas, was found uninfected. In common dolphins, the mean abundance of open ulcers per host was 1.1 (95% confidence interval: 0.8-1.3), with a maximum diameter (mean ± standard deviation) of 25.4 ± 16.9 mm. Stomachs with scars or extensive fibrosis putatively associated with Anisakis were detected in 14 and five animals, respectively. A molecular analysis based on the mitochondrial cytochrome c oxidase II gene using 18 worms from three cetacean species revealed single or mixed infections of Anisakis simplex sensu stricto and Anisakis pegreffii. Compared with the period 1991-1996, we found a strong increase of prevalence, abundance and extension of ulcerative lesions in most cetacean species. Anisakis populations could have increased in the study area over the last decades, although we cannot rule out that a higher environmental stress has also boosted the pathological effects of these parasites.

Tuberculosis peritoneal con presentación clínica como cáncer ovárico avanzado: revisión de la literatura / Peritoneal tuberculosis with clinical presentation as advanced ovarian cancer

Se presenta el caso de paciente con ascitis, masa pelviana y CA 125 elevado, sugerentes de cáncer ovárico avanzado. Se realizó laparoscopía que demostró lesiones compatibles con tuberculosis peritoneal. La biopsia laparoscópica de las lesiones demostró granulomas, por lo que no se realizó más cirugía y se inició tratamiento antituberculoso específico con buena respuesta clínica. Se revisa en la literatura tuberculosis peritoneal y su dificultad con el diagnóstico diferencial con cáncer de ovario avanzado.

It is presented the case of a patient with ascites, pelvic mass and elevated CA 125, all suggested of advanced ovarian cancer. It was made a laparoscopy that evidenced lesions of peritoneal tuberculosis. The laparoscopic biopsy of the lesions demostrated granulomas, for that there was no more surgery made and antituberculosis specific treatment was started, with good clinical response. It is revisited in the literature peritoneal tuberculosis and its difficult differential diagnoses with advanced ovarian cancer.

Efectos del entrenamiento fuerza-resistencia en el control de glucosa y función muscular en mujeres adultas sedentarias de Los Ángeles, Chile / Effects of resistance traininig on blood glucose control and muscle function in sedentary adult women in Los Ángeles, Chile

Introducción. El sedentarismo se asocia a múltiples alteraciones metabólicas como la insulinorresistencia y la diabetes mellitus tipo II. Recientes estudios indican que el ejercicio de fuerza-resistencia es efectivo en contrarrestar estas alteraciones metabólicas. Objetivo. Analizar efectos metabólicos y físicos de un programa de entrenamiento de fuerza-resistencia en 40 mujeres de entre 30 y 60 años, sedentarias, trabajadoras de la Universidad de Concepción, Los Ángeles, Chile durante septiembre-diciembre del 2013. Materiales y métodos. Los participantes fueron asignados aleatoriamente a un grupo de trabajo que realizó un programa de entrenamiento de fuerza o a un grupo control que no realizó ejercicio físico. El grupo de trabajo entrenó 4 grandes grupos musculares (flexores de brazo y tronco, extensores de brazo y pierna) 2 veces por semana durante un periodo de 12 semanas. Se midió tolerancia a la glucosa a través de la glucemia basal en ayunas y 120 minutos después de haber ingerido glucosa anhidra disuelta en agua. Además, se midió fuerza-resistencia de los grupos musculares entrenados a través de una «multiestación life fitness 3». Resultados. El grupo de trabajo disminuyó los niveles de glucemia basal (p = 0,023) en comparación a la evaluación inicial, en cambio el grupo control los aumentó (p = 0,006). En relación a la fuerza-resistencia, el grupo de trabajo mostró mejoras significativas en los cuatro grupos musculares evaluados en comparación al grupo control (flexores de brazos; p = 0,001), (flexores de tronco; p = 0,000), (extensores de brazos; p = 0,000) y (extensores de piernas; p = 0,000). Conclusiones. El entrenamiento de fuerza es capaz de disminuir los niveles de glucemia basal B, además de incrementar la fuerza-resistencia muscular en mujeres adultas sedentarias (AU)

Introduction. A sedentary lifestyle is associated with numerous metabolic diseases, such as insulin resistance and type 2 diabetes mellitus. Recent studies have reported that resistance exercise is an effective method to counteract these metabolic diseases. Objective. To analyze the metabolic and physical effects of a 12-week resistance exercise program in 40 sedentary women aged between 30 and 60 years who worked at the University of Concepcion, Los Ángeles, Chile. The study was conducted between September and December, 2013. Materials and methods. Participants were randomly assigned to either an experimental group or to a control group. The experimental group trained four large muscle groups (arm flexors, trunk flexors, arm extensors and leg extensors) twice a week for 12 weeks. Glucose tolerance was measured with a fasting glucose test at baseline and 120 minutes after ingestion of anhydrous glucose dissolved in water. Besides, muscular resistance was measured through a 'life fitness multi station 3'. Results. Fasting glucose levels decreased in the experimental group (p = .023) but increased in the control group (p = .006). Muscle strength significantly improved in the four muscle groups evaluated in the experimental group compared with the control group (arm flexors; p = .001), (trunk flexors; p = .000), (arm extensors; p = .000) and (leg extensors; p = .000). Conclusions. Strength training can reduce fasting glucose levels and increase muscle strength in sedentary adult women (AU)

Cáncer serosopélvico de alto grado: evidencia sobre su origen en la trompa de Falopio / High-grade serous pelvic cancer: evidence of its origin in the fallopian tube

Cáncer epitelial de ovario es una enfermedad altamente letal. Constituye la quinta causa de muerte por cáncer en mujeres a nivel mundial. El subtipo histológico más frecuente es el carcinoma seroso de alto grado. Este es el responsable de la alta letalidad de la enfermedad. Se presenta evidencia que respalda el origen tubario de este tipo histológico desde lesiones precursoras. A partir de estos datos se ha establecido que el cáncer tradicionalmente conocido como cáncer ovárico seroso de alto grado, el cáncer de trompa de Falopio y el carcinoma peritoneal primario, corresponden a una misma entidad nosológica: cáncer seroso pélvico de alto grado. Se revisa además la evidencia disponible para establecer que la salpingectomía podría constituir una medida de prevención para este tipo de cáncer.

Epithelial ovarian cancer is a highly lethal disease. It is the 5th cause of cancer death in women worldwide. The most common histologic subtype is the high-grade serous carcinoma. This is the responsible for the high lethality of the disease. Evidence supporting the tubal origin of this histological type from precursor lesions is presented. From these data it has been established that cancer traditionally known as serous high-grade ovarian cancer, cancer of the fallopian tube and primary peritoneal carcinoma, correspond to a single disease entity: pelvic serous high-grade cancer. We also check the available evidence to establish that the salpingectomy could be a preventive measure for this type of cancer.

Epstein-Barr virus-specific CD8(+) T lymphocytes from diffuse large B cell lymphoma patients are functionally impaired.

Epstein-Barr virus (EBV) is a persistent virus with oncogenic capacity that has been implicated in the development of aggressive B cell lymphomas, primarily in immunosuppressed individuals, although it can be present in immunocompetent individuals. Changes in the function and clonal diversity of T lymphocytes might be implied by viral persistence and lymphoma development. The aim of the present study was to evaluate the frequency, phenotype, function and clonotypical distribution of EBV-specific T cells after peripheral blood stimulation with a virus lysate in newly diagnosed patients with diffuse large B cell lymphoma (DLBCL) aged more than 50 years without prior histories of clinical immunosuppression compared with healthy controls. Our results showed impaired EBV-specific immune responses among DLBCL patients that were associated primarily with decreased numbers of central and effector memory CD8(+) T lymphocytes. In contrast to healthy controls, only a minority of the patients showed CD4(+)/tumour necrosis factor (TNF)-α(+) T cells expressing T cell receptor (TCR)-Vß17 and CD8(+)/TNF-α(+) T cells with TCR-Vß5·2, Vß9 and Vß18 in response to EBV. Notably, the production of TNF-α was undetectable among TCR-Vß5·3(+), Vß11(+), Vß12(+), Vß16(+) and Vß23(+) CD8(+) T cells. In addition, we observed decreased numbers of CD4(+)/TNF-α(+) and CD8(+)/TNF-α(+), CD8(+)/interleukin (IL)-2(+) and CD8(+)/TNF-α(+)/IL-2(+) T lymphocytes in the absence of T cells capable of producing TNF-α, IL-2 and IFN-γ after EBV stimulation simultaneously. Moreover, DLBCL patients displayed higher IL-10 levels both under baseline conditions and after EBV stimulation. These findings were also observed in patients with positive EBV viral loads. Prospective studies including a large number of patients are needed to confirm these findings.

Pseudogenization of sopA and sopE2 is functionally linked and contributes to virulence of Salmonella enterica serovar Typhi.

The difference in host range between Salmonella enterica serovar Typhimurium (S. Typhimurium) and S. enterica serovar Typhi (S. Typhi) can be partially attributed to pseudogenes. Pseudogenes are genomic segments homologous to functional genes that do not encode functional products due to the presence of genetic defects. S. Typhi lacks several protein effectors implicated in invasion or other important processes necessary for full virulence of S. Typhimurium. SopA and SopE2, effectors that have been lost by pseudogenization in S. Typhi, correspond to an ubiquitin ligase involved in cytokine production by infected cells, and to a guanine exchange factor necessary for invasion of epithelial cells, respectively. We hypothesized that sopA and/or sopE pseudogenization contributed to the virulence of S. Typhi. In this work, we found that S. Typhi expressing S. Typhimurium sopE2 exhibited a decreased invasion in different epithelial cell lines compared with S. Typhi WT. S. Typhimurium sopA completely abolished the hypo-invasive phenotype observed in S. Typhi expressing S. Typhimurium sopE2, suggesting that functional SopA and SopE2 participate concertedly in the invasion process. Finally, the expression of S. Typhimurium sopA and/or sopE2 in S. Typhi, determined changes in the secretion of IL-8 and IL-18 in infected epithelial cells.

Salmonella enterica serovar Typhimurium BaeSR two-component system positively regulates sodA in response to ciprofloxacin.

In response to antibiotics, bacteria activate regulatory systems that control the expression of genes that participate in detoxifying these compounds, like multidrug efflux systems. We previously demonstrated that the BaeSR two-component system from Salmonella enterica serovar Typhimurium (S. Typhimurium) participates in the detection of ciprofloxacin, a bactericidal antibiotic, and in the positive regulation of mdtA, an efflux pump implicated in antibiotic resistance. In the present work, we provide further evidence for a role of the S. Typhimurium BaeSR two-component system in response to ciprofloxacin treatment and show that it regulates sodA expression. We demonstrate that, in the absence of BaeSR, the transcript levels of sodA and the activity of its gene product are lower. Using electrophoretic mobility shift assays and transcriptional fusions, we demonstrate that BaeR regulates sodA by a direct interaction with the promoter region.

Quantum key distribution session with 16-dimensional photonic states.

The secure transfer of information is an important problem in modern telecommunications. Quantum key distribution (QKD) provides a solution to this problem by using individual quantum systems to generate correlated bits between remote parties, that can be used to extract a secret key. QKD with D-dimensional quantum channels provides security advantages that grow with increasing D. However, the vast majority of QKD implementations has been restricted to two dimensions. Here we demonstrate the feasibility of using higher dimensions for real-world quantum cryptography by performing, for the first time, a fully automated QKD session based on the BB84 protocol with 16-dimensional quantum states. Information is encoded in the single-photon transverse momentum and the required states are dynamically generated with programmable spatial light modulators. Our setup paves the way for future developments in the field of experimental high-dimensional QKD.

Características polínicas y composición química del polen apícola colectado en Cayaltí (Lambayeque - Perú) / Pollinic characteristics and chemical composition of bee pollen collected in Cayalti (Lambayeque - Peru)

El objetivo del presente estudio fue determinar las características polínicas y la composición química del polen apícola, colectado en El Cafetal, Cayaltí (Lambayeque, Perú), un área rural del bosque estacionalmente seco. El polen apícola se colectó directamente de las colmenas y se clasificó en cuatro grupos de colores: amarillo, anaranjado, crema y gris. El análisis polínico reveló la presencia de polen de las especies: Acacia macracantha Humboldt & Bonpland, Encelia canescens Lamarck, Momordica charantia L. y Prosopis pallida (Humboldt & Bonpland ex Willdenow) H.B.K. El polen de P. pallida predominó en el polen apícola gris (98,1%) y amarillo (87,7%) en tanto que el polen de E. canescens predominó en el polen apícola anaranjado (72,7%) y crema (50,0%). Se observó una gran diversidad en las características morfológicas del polen, en la forma (poliada, oblado esferoidal y prolado esferoidal), elementos esculturales (liso, espinado y reticulado) y aberturas (tricolporado y estefanocolpado). Se determinó los contenidos de humedad (8,8 - 13,8%), cenizas (2,1 - 3,2%), calcio (6,4 - 12,4%), vitamina C (208 - 504 mg), azúcares totales y reductores (35 - 49,7 y 22,4 - 26%, respectivamente), grasas (0,15 - 0,18%) y proteínas (13,7 - 17,3%), observándose significativas variaciones en función del color del polen apícola. El valor nutritivo fue mayor en el polen apícola gris alcanzando el valor 3,51; en este color de polen apícola predominó P. pallida.

The aim of this study was to determine the pollen and chemical composition offour types ofbee pollen, collected in The Cafetal, Cayaltí (Lambayeque, Perú), a rural area of Perú seasonally dry forest. Bee pollen was collected directly from the hives and classified into four groups ofcolors: yellow, orange, cream and gray. Pollen analysis revealed the presence ofpollen in species: Acacia macracantha Humboldt & Bonpland, Encelia canescens Lamarck, Momordica charantia L. and Prosopis pallida (Humboldt & Bon-pland ex Willdenow) H.B.K. The pollen of P. pallida was predominant in the gray (98,1%) and yellow (87,7%) bee pollen; while pollen of E. canecens was predominant in the orange (72,7%) and cream (50,0%) bee pollen, respectively. A great diversity in the pollen morphology (polyad, oblate spheroidal and prolate spheroidal), scultural elements (psilate, echinate and reticulate) and openings (tricolporate and stephanocolpate) was observed. The moisture (8,8 - 13,8%), ash content (2,1 - 3,2%), calcium (6,4 - 12,4%), vitamin C (208 - 504 mg), total and reducing sugars (35 - 49,7y 22,4 - 26%, respectively), fat (0,15 - 0,18%) and proteins (13,7 - 17,3%) was determined, showing significant variations depending on the color of bee pollen. The nutritive value was higher in the gray bee pollen reaching the value 3.51; in this color was predominant P. pallida pollen.

ompW is cooperatively upregulated by MarA and SoxS in response to menadione.

OmpW is a minor porin whose biological function has not been clearly defined. Evidence obtained in our laboratory indicates that in Salmonella enterica serovar Typhimurium the expression of OmpW is activated by SoxS upon exposure to paraquat and it is required for resistance. SoxS belongs to the AraC family of transcriptional regulators, like MarA and Rob. Due to their high structural similarity, the genes under their control have been grouped in the mar/sox/rob regulon, which presents a DNA-binding consensus sequence denominated the marsox box. In this work, we evaluated the role of the transcription factors MarA, SoxS and Rob of S. enterica serovar Typhimurium in regulating ompW expression in response to menadione. We determined the transcript and protein levels of OmpW in different genetic backgrounds; in the wild-type and Δrob strains ompW was upregulated in response to menadione, while in the ΔmarA and ΔsoxS strains the induction was abolished. In a double marA soxS mutant, ompW transcript levels were lowered after exposure to menadione, and only complementation in trans with both genes restored the positive regulation. Using transcriptional fusions and electrophoretic mobility shift assays with mutant versions of the promoter region we demonstrated that two of the predicted sites were functional. Additionally, we demonstrated that MarA increases the affinity of SoxS for the ompW promoter region. In conclusion, our study shows that ompW is upregulated in response to menadione in a cooperative manner by MarA and SoxS through a direct interaction with the promoter region.

Simultaneous rotation, orientation and displacement control of birefringent microparticles in holographic optical tweezers.

We report the experimental implementation of a new method for generating multiple dynamical optical tweezers, where each one of them is generated with an independent linear polarization state with arbitrary orientation. This also allows an independent simultaneous polarization-rotation control. The laser beam, both for generating multiple traps and polarization control, has been modulated using a single reflective nematic liquid crystal with parallel alignment. We present experimental results of controlled displacement, orientation and rotation of birefringent particles. In addition, a simple method for estimating and canceling out the primary astigmatism present in the system is presented.

Relentless increase of resistance to fluoroquinolones and expanded-spectrum cephalosporins in Escherichia coli: 20 years of surveillance in resource-limited settings from Latin America.

Previous studies on commensal Escherichia coli from healthy children in the Bolivian Chaco have shown remarkable resistance rates to the old antibiotics since the early 1990s, and the emergence of resistance to newer drugs (fluoroquinolones and expanded-spectrum cephalosporins) in the 2000s. Here we report the results of a new survey conducted in 2011 in the same setting. Rectal swabs were obtained from 482 healthy children (aged 6-72 months) from three urban areas of the Bolivian Chaco. Screening for antibiotic-resistant E. coli was performed by a direct plating method, as in the previous studies. The blaCTX-M genes were investigated by PCR/sequencing, and CTX-M-producing isolates were subjected to genotyping and detection of several plasmid-mediated quinolone resistance mechanisms. Results showed high rates of resistance to nalidixic acid (76%), ciprofloxacin (44%) and expanded-spectrum cephalosporins (12.4%), demonstrating a relentless increase of resistance to those drugs over the past two decades. CTX-M-type extended-spectrum beta-lactamases were found to be widespread (12%, 97% of extended-spectrum beta-lactamase producers). Compared with the previous studies, CTX-M-producing E. coli underwent a dramatic dissemination (120-fold increase since early 2000s) and a radical change of dominant CTX-M groups (CTX-M-1 and CTX-M-9 groups versus CTX-M-2 group). Most CTX-M producers were not susceptible to quinolones (91%), and 55% carried plasmid-mediated quinolone resistance genes (different combinations of aac(6')-Ib-cr, qnrB and qepA). This study shows the rapid and remarkable increasing trend for resistance to fluoroquinolones and expanded-spectrum cephalosporins in one of the poorest regions of Latin America, and underscores the need for urgent control strategies aimed at preserving the efficacy of those drugs in similar settings.

Differential expression of the transcription factors MarA, Rob, and SoxS of Salmonella Typhimurium in response to sodium hypochlorite: down-regulation of rob by MarA and SoxS.

To survive, Salmonella enterica serovar Typhimurium (S. Typhimurium) must sense signals found in phagocytic cells and modulate gene expression. In the present work, we evaluated the expression and cross-regulation of the transcription factors MarA, Rob, and SoxS in response to NaOCl. We generated strains ΔsoxS and ΔmarA, which were 20 times more sensitive to NaOCl as compared to the wild-type strain; while Δrob only 5 times. Subsequently, we determined that marA and soxS transcript and protein levels were increased while those of rob decreased in a wild-type strain treated with NaOCl. To assess if changes in S. Typhimurium after exposure to NaOCl were due to a cross-regulation, as in Escherichia coli, we evaluated the expression of marA, soxS, and rob in the different genetic backgrounds. The positive regulation observed in the wild-type strain of marA and soxS was retained in the Δrob strain. As in the wild-type strain, rob was down-regulated in the ΔmarA and ΔsoxS treated with NaOCl; however, this effect was decreased. Since rob was down-regulated by both factors, we generated a ΔmarA ΔsoxS strain finding that the negative regulation was abolished, confirming our hypothesis. Electrophoretic mobility shift assays using MarA and SoxS confirmed an interaction with the promoter of rob.

Characterization of the BaeSR two-component system from Salmonella Typhimurium and its role in ciprofloxacin-induced mdtA expression.

Two-component systems are one of the most prevalent mechanisms by which bacteria sense, respond and adapt to changes in their environment. The activation of a sensor histidine kinase leads to autophosphorylation of a conserved histidine residue followed by transfer of the phosphoryl group to a cognate response regulator in an aspartate residue. The search for antibiotics that inhibit molecular targets has led to study prokaryotic two-component systems. In this study, we characterized in vitro and in vivo the BaeSR two-component system from Salmonella Typhimurium and evaluated its role in mdtA regulation in response to ciprofloxacin treatment. We demonstrated in vitro that residue histidine 250 is essential for BaeS autophosphorylation and aspartic acid 61 for BaeR transphosphorylation. By real-time PCR, we showed that mdtA activation in the presence of ciprofloxacin depends on both members of this system and that histidine 250 of BaeS and aspartic acid 61 of BaeR are needed for this. Moreover, the mdtA expression is directly regulated by binding of BaeR at the promoter region, and this interaction is enhanced when the protein is phosphorylated. In agreement, a BaeR mutant unable to phosphorylate at aspartic acid 61 presents a lower affinity with the mdtA promoter.

Experimental quantum tomography of photonic qudits via mutually unbiased basis.

We present the experimental quantum tomography of 7- and 8-dimensional quantum systems based on projective measurements in the mutually unbiased basis (MUB-QT). One of the advantages of MUB-QT is that it requires projections from a minimal number of bases to be performed. In our scheme, the higher dimensional quantum systems are encoded using the propagation modes of single photons, and we take advantage of the capabilities of amplitude- and phase-modulation of programmable spatial light modulators to implement the MUB-QT.

cAMP receptor protein (CRP) positively regulates the yihU-yshA operon in Salmonella enterica serovar Typhi.

Salmonella enterica serovar Typhi (S. Typhi) is the aetiological agent of typhoid fever in humans. This bacterium is also able to persist in its host, causing a chronic disease by colonizing the spleen, liver and gallbladder, in the last of which the pathogen forms biofilms in order to survive the bile. Several genetic components, including the yihU-yshA genes, have been suggested to be involved in the survival of Salmonella in the gallbladder. In this work we describe how the yihU-yshA gene cluster forms a transcriptional unit regulated positively by the cAMP receptor global regulator CRP (cAMP receptor protein). The results obtained show that two CRP-binding sites on the regulatory region of the yihU-yshA operon are required to promote transcriptional activation. In this work we also demonstrate that the yihU-yshA transcriptional unit is carbon catabolite-repressed in Salmonella, indicating that it forms part of the CRP regulon in enteric bacteria.