CarD stabilizes mycobacterial open complexes via a two-tiered kinetic mechanism

CarD is an essential and global transcriptional regulator in mycobacteria. While its biological role is unclear, CarD functions by interacting directly with RNA polymerase (RNAP) holoenzyme promoter complexes. Here, using a fluorescent reporter of open complex, we quantitate RP(o) formation in real time and show that Mycobacterium tuberculosis CarD has a dramatic effect on the energetics of RNAP bound complexes on the M. tuberculosis rrnAP3 ribosomal RNA promoter. The data reveal that Mycobacterium bovis RNAP exhibits an unstable RP(o) that is stabilized by CarD and suggest that CarD uses a two-tiered, concentration-dependent mechanism by associating with open and closed complexes with different affinities. Specifically, the kinetics of open-complex formation can be explained by a model where, at saturating concentrations of CarD, the rate of bubble collapse is slowed and the rate of opening is accelerated. The kinetics and open-complex stabilities of CarD mutants further clarify the roles played by the key residues W85, K90 and R25 previously shown to affect CarD-dependent gene regulation in vivo. In contrast to M. bovis RNAP, Escherichia coli RNAP efficiently forms RP(o) on rrnAP3, suggesting an important difference between the polymerases themselves and highlighting how transcriptional machinery can vary across bacterial genera

Estudio comparativo del fraccionamiento de los carbohidratos de la miel mediante tratamiento con carbón activo y levaduras para la detección de adulteraciones

Recientemente se ha descrito la utilidad de los anhídridos de difructosa (DFAs) como buenos marcadores para la detección de adulteraciones de miel con jarabes de alto contenido en fructosa (HFCS) y de azúcar invertido (IS). Sin embargo, para la detección de estos compuestos es necesario realizar un fraccionamiento previo de los carbohidratos de estas muestras, dado que la alta concentración de monosacáridos (glucosa y fructosa) presentes en la miel dificulta el análisis de los compuestos minoritarios. Por tanto, el objetivo de este trabajo se basó en la comparación de un tratamiento con levaduras propuesto con anterioridad y un fraccionamiento con carbónactivo para eliminar la fracción de monosacáridos,concentrando así los compuestos minoritarios de la miely en concreto los DFAs presentes en muestras adulteradas.Se llevó a cabo la optimización de dichos métodos para conseguir el mayor enriquecimiento en DFAs comprobándose que ambos son útiles para la detección de adulteraciones de miel de hasta un 5% de HFCS e IS

Una nueva especie del grupo Liolaemus elongatus (Iguania: Liolaemidae) de la provincia de Neuquén, Argentina, con comentarios sobre su morfología genital

The Liolaemus elongatus group is a group of lizards that ranges from northwestern Argentina to the southern Patagonian steppe. In this study, we describe a new species of the L. elongatus group. The new taxon is distributed in the vicinity of L. burmeisteri, L. crandalli, L. gununakuna, L. punmahuida and L. tregenzai, and posseses a combination of unique character states and morphological characters that allows its formal description as a new species. The morphological evidence provides strong support that the population under study corresponds to a new taxon. With the description of the new species, the number of members of the L. elongatus group rises to twenty-two, but many populations likely represent undescribed species.El grupo de Liolaemus elongatus es un grupo de lagartijas que se distribuye desde el noroeste de Argentina al sur de las estepas patagónicas. En el presente estudio, describimos una nueva especie perteneciente al grupo de L. elongatus. El nuevo taxón se distribuye en cercanías de L. burmeisteri, L. crandalli, L. gununakuna, L. punmahuida y L. tregenzai, y la combinación de caracteres morfológicos en lepidosis y morfométricos permite describirla como nueva especie. La evidencia morfológica aporta un fuerte soporte que la población estudiada corresponde a un nuevo Liolaemus. Con la descripción de este nuevo taxón el número de especies del grupo de L. elongatus asciende a veintidós, aunque hay varias poblaciones que corresponden a especies no descritas.Asociación Herpetológica Argentin

Seroepidemiological study of Q fever in domestic ruminants in semi-extensive grazing systems

<p>Abstract</p> <p>Background</p> <p>Q fever, a worldwide zoonotic disease caused by <it>Coxiella burnetii</it>, is endemic in northern Spain where it has been reported as responsible for large series of human pneumonia cases and domestic ruminants' reproductive disorders. To investigate pathogen exposure among domestic ruminants in semi-extensive grazing systems in northern Spain, a serosurvey was carried out in 1,379 sheep (42 flocks), 626 beef cattle (46 herds) and 115 goats (11 herds). Serum antibodies were analysed by ELISA and positive samples were retested by Complement Fixation test (CFT) to detect recent infections.</p> <p>Results</p> <p>ELISA anti-<it>C. burnetii </it>antibody prevalence was slightly higher in sheep (11.8 ± 2.0%) than in goats (8.7 ± 5.9%) and beef cattle (6.7 ± 2.0%). Herd prevalence was 74% for ovine, 45% for goat and 43% for bovine. Twenty-one percent of sheep flocks, 27% of goat and 14% of cattle herds had a <it>C. burnetii </it>seroprevalence ≥ 20%. Only 15 out of 214 ELISA-positive animals reacted positive by CFT. Age-associated seroprevalence differed between ruminant species with a general increasing pattern with age. No evidence of correlation between abortion history and seroprevalence rates was observed despite the known abortifacient nature of <it>C. burnetii </it>in domestic ruminants.</p> <p>Conclusions</p> <p>Results reported herein showed that sheep had the highest contact rate with <it>C. burnetii </it>in the region but also that cattle and goats should not be neglected as part of the domestic cycle of <it>C. burnetii</it>. This work reports basic epidemiologic patterns of <it>C. burnetii </it>in semi-extensive grazed domestic ruminants which, together with the relevant role of <it>C. burnetii </it>as a zoonotic and abortifacient agent, makes these results to concern both Public and Animal Health Authorities.</p

Response of obesity-resistant BALB/c mice to a ketogenic diet

Introduction. The ketogenic diet (KD) is a high-fat, low-carbohydrate diet in which the body undergoes metabolic adjustments that stimulate ketogenesis, thereby increasing circulating ketone bodies. Loss of body weight is attributed to these adjustments, as well as neuroprotective properties. However, the mechanisms involved are still not fully elucidated. That aim of this work was to evaluate the effect of a ketogenic diet on body composition, feeding behavior and glucose metabolism in mice of the BALB/c strain, a mouse model resistant to obesity. Materials and methods. BALB/c mice of both sexes, 12 weeks old, were divided into KD and control groups, which received a ketogenic diet (Research Diets) or standard chow (LabDiet 5001), respectively, for 23 days. Throughout the experiment, body weight gain, water and food intake were measured, whereas body mass index (BMI), the percentage of interscapular, inguinal, and visceral adipose tissue and blood b-hidroxybutyrate levels were measured at the end of the protocol. In addition, glucose tolerance tests were carried out at the beginning and at the end of the experiment. Results. Similar body weight gain (10%) was observed in males and females on KD compared to the control group (p\u3c0.05). However, a higher BMI was observed only in males. The KD group consumed 50% less food in both sexes, whereas water consumption was diminished 25% in males and 50% in females, compared to the control (p= 0.0001). The estimated energy intake was lower (12 Kcal) in males on ketogenic diet, but not in females. Regarding the metabolic state at day 23, in KD mice levels of b-hidroxybutyrate increased to 0.4 mmol/L in males and 0.7 mmol/L in females. Mice of both sexes on KD showed increased inguinal and visceral fat, when compared to the control group on standard chow. At day 23, the glucose tolerance test showed an increase in the area under the curve, indicating impaired glucose tolerance, in both males and females on KD. Conclusions. In obesity-resistant BALB/c mice, the consumption of a ketogenic diet for a short period induces a state of nutritional ketosis accompanied by weight gain, increased fat tissue, and impaired glucose intolerance

Effects of increasing the affinity of CarD for RNA polymerase on Mycobacterium tuberculosis growth, rRNA transcription, and virulence

CarD is an essential RNA polymerase (RNAP) interacting protein in Mycobacterium tuberculosis that stimulates formation of RNAP-promoter open complexes. CarD plays a complex role in M. tuberculosis growth and virulence that is not fully understood. Therefore, to gain further insight into the role of CarD in M. tuberculosis growth and virulence, we determined the effect of increasing the affinity of CarD for RNAP. Using site-directed mutagenesis guided by crystal structures of CarD bound to RNAP, we identified amino acid substitutions that increase the affinity of CarD for RNAP. Using these substitutions, we show that increasing the affinity of CarD for RNAP increases the stability of the CarD protein in M. tuberculosis. In addition, we show that increasing the affinity of CarD for RNAP increases the growth rate in M. tuberculosis without affecting 16S rRNA levels. We further show that increasing the affinity of CarD for RNAP reduces M. tuberculosis virulence in a mouse model of infection despite the improved growth rate in vitro. Our findings suggest that the CarD-RNAP interaction protects CarD from proteolytic degradation in M. tuberculosis, establish that growth rate and rRNA levels can be uncoupled in M. tuberculosis and demonstrate that the strength of the CarD-RNAP interaction has been finely tuned to optimize virulence. IMPORTANCE Mycobacterium tuberculosis, the causative agent of tuberculosis, remains a major global health problem. In order to develop new strategies to battle this pathogen, we must gain a better understanding of the molecular processes involved in its survival and pathogenesis. We have previously identified CarD as an essential transcriptional regulator in mycobacteria. In this study, we detail the effects of increasing the affinity of CarD for RNAP on transcriptional regulation, CarD protein stability, and virulence. These studies expand our understanding of the global transcription regulator CarD, provide insight into how CarD activity is regulated, and broaden our understanding of prokaryotic transcription

Alginate beads to improve viability of Lactobacillus plantarum to heat stress

Peer Reviewe

Action of sodium fluoride on phagocytosis by systemic polymorphonuclear leucocytes

This study was supported in part by the Education and Sciences Council of the Andalusian Regional Government through Project nº 082.Alterations in phagocytosis appear to be important in the onset and development of periodontitis. We investigated new substances that may be of use in the treatment of periodontitis. In a preliminary study, we tested the effect of sodium fluoride on phagocytosis by circulating polymorphonuclear leucocytes (PMNs) in 10 replicate assays using blood from six healthy subjects. Sodium fluoride was tested at concentrations of 1.0 micron to 4.0 microns against Streptococcus oralis, Streptococcus mutans, Streptococcus sobrinus and Streptococcus sanguis. The phagocytic index against all microorganisms increased significantly at all concentrations of sodium fluoride assayed; this effect was dose dependent. Sodium fluoride appeared to stimulate phagocytosis via two mechanisms: an apparent increase in bacterial susceptibility to phagocytosis, and direct stimulation of phagocytosis by PMNs.Andalusian Regional Governmen

El perfil de clima escolar: estudio transcultural de la validez de una batería de cuestionarios para evaluar el clima escolar

This paper studies the validity of the School Climate Battery of Questionnaires for Secondary and High School Teachers (SCBQSHST). The battery includes five questionnaires: Quality of Leadership, Quality of Teachers' Support, School Motivational Orientation, Quality of Students' Attitude, and Quality of Parental Support. A total of 178 teachers from Costa Rica were compared with 343 Spanish teachers. Confirmatory factor analyses showed that the questionnaires allow assessing teachers' perceptions of the different dimensions of school climate in a valid and reliable way in both Spain and Costa Rica. Differences in the perception of Spanish and Costa Rican teachers about school climate shown by multigroup confirmatory factor analyses are discussed as well as theoretical and practical implications.Este artículo estudia la validez de la Batería de cuestionarios sobre clima escolar para profesores de Secundaria y Bachillerato (BQCE-SB). La batería incluye cinco cuestionarios: calidad de liderazgo, calidad de apoyo docente, orientación motivacional del centro, calidad de las actitudes de los estudiantes y calidad del apoyo de los padres. Un total de 178 docentes de Costa Rica se compararon con 343 docentes españoles. Los análisis factoriales confirmatorios mostraron que los cuestionarios permiten evaluar de manera válida y confiable las percepciones de los docentes sobre las diferentes dimensiones del clima escolar, tanto en España como en Costa Rica. Se discuten las diferencias en la percepción de los docentes españoles y costarricenses sobre el clima escolar que muestran los análisis factoriales confirmatorios multigrupo, así como sus implicaciones teóricas y práctica