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Made available in DSpace on 2022-04-29T08:32:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 The interaction of enteroaggregative Escherichia coli (EAEC) strains with the colonic gut mucosa is characterized by the ability of the bacteria to form robust biofilms, to bind mucin, and induce a local inflammatory response. These events are mediated by a repertoire of five different aggregative adherence fimbriae variants (AAF/I-V) typically encoded on virulence plasmids. In this study, we report the production in EAEC strains of a new YehD fimbriae (YDF), which is encoded by the chromosomal gene cluster yehABCD, also present in most E. coli strains. Immuno-labelling of EAEC strain 042 with anti-AAF/II and anti-YDF antibodies demonstrated the presence of both AAF/II and YDF on the bacterial surface. We investigated the role of YDF in cell adherence, biofilm formation, colonization of spinach leaves, and induction of pro-inflammatory cytokines release. To this aim, we constructed yehD deletion mutants in different EAEC backgrounds (strains 17-2, 042, 55989, C1010, 278-1, J7) each harbouring one of the five AAFs. The effect of the YDF mutation was strain dependent and AAF independent as the lack of YDF had a different impact on the phenotypes manifested by the different EAECs tested. Expression of the yehABCD operon in a E. coli K12 ORN172 showed that YDF is important for biofilm formation but not for adherence to HeLa cells. Lastly, screening of pro-inflammatory cytokines in supernatants of Caco-2 cells infected with EAEC strains 042 and J7 and their isogenic ΔyehD mutants showed that these mutants were significantly defective in release of IL-8 and TNF-α. This study contributes to the understanding of the complex and diverse mechanisms of adherence of EAEC strains and identifies a new potential target for preventive measures of gastrointestinal illness caused by EAEC and other E. coli pathogroups. Department of Pediatrics University of Virginia School of Medicine Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias Centro Médico Nacional Siglo XXI Instituto Mexicano de Seguro Social Centro de Detección Biomolecular Benemérita Universidad Autónoma de Puebla University of Florida Emerging Pathogens Institute Departamento de Patologia Universidade Federal do Maranhão Departamento de Microbiologia e Imunologia Instituto de Biociencias da UNESP Facultad de Estomatología Benemérita Universidad Autónoma de Puebla Departamento de Biología Celular Centro de Investigaciones Avanzadas Instituto Politécnico Nacional Centro de Investigaciones en Ciencias Microbiológicas Benemérita Universidad Autónoma de Puebla Laboratory of Bacteriology Instituto Butantan Departamento de Microbiologia e Imunologia Instituto de Biociencias da UNESP

Se evaluó el efecto de la suplementación con metionina de cromo (Met-Cr) sobre el desempeño productivo y características de la canal en cerdos en finalización. Se evaluaron 3 tratamientos; 1) testigo en donde los cerdos fueron alimentados con dietas de finalización de 60 a 100 kg; 2) testigo + 0.8 mg de Cr/kg de alimento desde 60 hasta 100 kg; y 3) testigo + 0.8 mg de Cr/kg de alimento desde 80 hasta 100 kg. Los cerdos suplementados con MetCr consumieron menos alimento (P≤0.05), crecieron más rápido (P≤0.05) y fueron más pesados (P≤0.05) y más eficientes (P≤0.05) que los cerdos testigo, pero el efecto benéfico fue mayor cuando la suplementación inició a menor peso. La adición de Met-Cr incrementó el área del músculo Longissimus dorsi (P≤0.01), el rendimiento de canal (P≤0.01) y redujo el espesor de grasa dorsal (P≤0.01). Además, la carne de cerdos suplementados presentó valores de pH y luminosidad (L*) más bajos (P≤0.01) que de cerdos testigo. Incluso, el consumo de Met-Cr redujo las pérdidas a la cocción (P≤0.01) y la fuerza de corte (P≤0.01), pero el efecto sobre la suavidad fue mayor al suplementar a menor peso. En conclusión, la suplementación de Met-Cr en cerdos mejora el desempeño productivo, las características de la canal y algunos indicadores de calidad de la carne, pero la etapa en que inicia la suplementación con Cr puede afectar la respuesta animal.

Avian pathogenic Escherichia coli (APEC) causes localized and systemic avian infections and is responsible for considerable economic losses in the poultry industry. This organism adheres and invades human and avian cells, however, the regulatory networks that dictate its virulence are largely unknown. The CpxRA two-component system is responsible for sensing and controlling outer-membrane stress and detecting misfolded proteins in the bacterial periplasmic space. CpxA is a membrane sensor kinase and CpxR is a cytoplasmic transcriptional regulator. In this study, we found that the CpxRA system regulates the virulence properties of APEC. Adherence, invasiveness, motility, production of type 1 fimbriae and biofilm were negatively affected in the ΔcpxA mutant indicating that the CpxA is required for full manifestation of these phenotypes. We also found that CpxR-P directly bound to the fimA promoter, locking the fimS region of type 1 fimbriae in the phase-OFF orientation. In addition, the absence of CpxA also reduced flagella production strongly suggesting that CpxRA regulates these two important surface organelles in APEC. This study provides compelling evidence of the role of the CpxRA two-component system in the regulation of virulence factors of avian pathogenic E. coli.

Solvent extraction of soybean creates soybean meal (SBM), but an array of other soybean products can be created using further processing of SBM or soybean. For accurate inclusion of these products in pig feed, characterization of digestible AA profile and energy value is required. Soybean products from processes such as extrusion (EX) of soybean and thermo-mechanical (TM) treatment, bioconversion using fermentation or enzymes (BC), and ethanol-water extraction (EW) of soybean meal were collected together with SBM. These 9 soybean products were tested in cornstarch-based diets together with an N-free diet for a total of 10 diets. Ten ileal-cannulated barrows (30.4 ± 0.7 kg initial BW) were fed 10 diets at 2.8 times maintenance DE for six 9-d periods with a 6 (periods) × 10 (pigs) Youden square. The control SBM contained 47.0% CP, 1.4% ether extract, and ADF 6.0%. The 9 soybean products contained 35.6% to 66.4% CP, 0.9% to 21.6% ether extract, and 4.4% to 8.0% ADF. The EW soybean products were high in CP (>61%), whereas the 2 EX soybean products were low in CP ( 0.05) among soybean products for most AA, except for lower SID of Arg, Ile, Leu, Lys, Phe, and Tyr (P < 0.05) for EX2 and BC1 than other soybean products. The DE and predicted NE value did not differ (P > 0.05) among soybean products. The greater SID AA content (P < 0.05) in EW, BC, and TM1 soybean products than SBM was mainly a result of greater total AA content due to removal of other macronutrients. In conclusion, extrusion of soybean creates soybean products with a greater energy value but lower ATTD of energy and lower SID AA content than SBM. Further processing of SBM creates soybean products with greater CP and SID AA content but similar SID of AA than SBM. Thus, new technologies to process SBM or soybean create high-value ingredients to be included in pig diets, especially for young pigs with high nutritional requirements.

Enterotoxigenic Escherichia coli produces a long type 4 pilus called Longus. The regulatory elements and the environmental signals controlling the expression of Longus-encoding genes are unknown. We identified two genes lngR and lngS in the Longus operon, whose predicted products share homology with transcriptional regulators. Isogenic lngR and lngS mutants were considerably affected in transcription of lngA pilin gene. The expression of lngA, lngR and lngS genes was optimally expressed at 37°C at pH 7.5. The presence of glucose and sodium chloride had a positive effect on Longus expression. The presence of divalent ions, particularly calcium, appears to be an important stimulus for Longus production. In addition, we studied H-NS, CpxR and CRP global regulators, on Longus expression. The response regulator CpxR appears to function as a positive regulator of lng genes as the cpxR mutant showed reduced levels of lngRSA expression. In contrast, H-NS and CRP function as negative regulators since expression of lngA was up-regulated in isogenic hns and crp mutants. H-NS and CRP were required for salt- and glucose-mediated regulation of Longus. Our data suggest the existence of a complex regulatory network controlling Longus expression, involving both local and global regulators in response to different environmental signals.

Avian pathogenic Escherichia coli (APEC) causes localized and systemic avian infections and is responsible for considerable economic losses in the poultry industry. This organism adheres and invades human and avian cells, however, the regulatory networks that dictate its virulence are largely unknown. The CpxRA two-component system is responsible for sensing and controlling outer-membrane stress and detecting misfolded proteins in the bacterial periplasmic space. CpxA is a membrane sensor kinase and CpxR is a cytoplasmic transcriptional regulator. In this study, we found that the CpxRA system regulates the virulence properties of APEC. Adherence, invasiveness, motility, production of type 1 fimbriae and biofilm were negatively affected in the ΔcpxA mutant indicating that the CpxA is required for full manifestation of these phenotypes. We also found that CpxR-P directly bound to the fimA promoter, locking the fimS region of type 1 fimbriae in the phase-OFF orientation. In addition, the absence of CpxA also reduced flagella production strongly suggesting that CpxRA regulates these two important surface organelles in APEC. This study provides compelling evidence of the role of the CpxRA two-component system in the regulation of virulence factors of avian pathogenic E. coli.

Enterotoxigenic Escherichia coli produces a long type 4 pilus called Longus. The regulatory elements and the environmental signals controlling the expression of Longus-encoding genes are unknown. We identified two genes lngR and lngS in the Longus operon, whose predicted products share homology with transcriptional regulators. Isogenic lngR and lngS mutants were considerably affected in transcription of lngA pilin gene. The expression of lngA, lngR and lngS genes was optimally expressed at 37°C at pH 7.5. The presence of glucose and sodium chloride had a positive effect on Longus expression. The presence of divalent ions, particularly calcium, appears to be an important stimulus for Longus production. In addition, we studied H-NS, CpxR and CRP global regulators, on Longus expression. The response regulator CpxR appears to function as a positive regulator of lng genes as the cpxR mutant showed reduced levels of lngRSA expression. In contrast, H-NS and CRP function as negative regulators since expression of lngA was up-regulated in isogenic hns and crp mutants. H-NS and CRP were required for salt- and glucose-mediated regulation of Longus. Our data suggest the existence of a complex regulatory network controlling Longus expression, involving both local and global regulators in response to different environmental signals.

Los seres vivos y el medio que los sostiene tienen una interdependencia obligada; cualquier evento ocurrido dentro de un ecosistema afecta a todas sus fracciones. El enfoque del proceso salud-enfermedad reconoce las influencias del medio ambiente. Para enfermedades autoinmunitarias como el lupus eritematoso sistemico (LES) o generalizado se ha reconocido la posibilidad de que se produzca por luz ultravioleta y exposicion al sol de manera prolongada. Los agentes microbianos pueden generar otras enfermedades como las artritis reactivas. Sustancias como la alfalfa son capaces de causar alguna enfermedad y los trabajadores de laboratorio que manipulan sueros de pacientes con enfermedades reumaticas autoinmunitarias se tornan positivos a los anticuerpos que estan trabajando. Es asi que las ciencias ambientales y el enfoque laboral permiten un nuevo abordaje para el estudio de los posibles mecanismos patogenicos en la aparicion de algunas enfermedades reumaticas. Este articulo revisa las principales evidencias existentes y plantea algunas hipotesis generadas a partir de esa misma revision

Living beings and the environment that supports them have a mutual interdependence and therefore any event that occurs within an ecosystem affects all parts. The influence that the environment has on subjects that may develop an illness has been amply recognized. For some autoimmune diseases such as systemic lupus erythematosus (SLE), the possibility of its development under ultraviolet light and prolonged exposure to sunlight has been recognized. Microorganisms may activate other illnesses such as reactive arthritis. Substances such as alfalfa are also able to unleash disease activity. Laboratory workers who manipulate sera of patients with autoimmune rheumatic disorders develop antibodies to the sera that they are working with. It is thus that environmental sciences and focused research allow the development of a new approach to the study of possible pathogenic mechanisms in the appearance of certain rheumatic disorders. This article reviews the main existing evidence and proposes certain hypotheses derived from it.

Living beings and the environment that supports them have a mutual interdependence and therefore any event that occurs within an ecosystem affects all parts. The influence that the environment has on subjects that maydevelop an illness has been amply recognized. For some autoimmune diseases such as systemic lupus erythematosus (SLE), the possibility of its development under ultraviolet light and prolonged exposure to sunlight has been recognized. Microorganisms may activate other illnesses such as reactive arthritis. Substances such as alfalfa are also able to unleash disease activity. Laboratory workers who manipulate sera of patients with autoimmune rheumatic disorders develop antibodies to the sera that they are working with. It is thus that environmental sciences and focused research allow the development of a new approach to the study of possible pathogenic mechanisms in the appearance of certain rheumatic disorders. This article reviews the main existing evidence and proposes certain hypotheses derived from it.

La viscosidad de la dieta provocada por algunos compuestos antinutricionales en los cereales puede afectar la pérdida de aminoácidos (AA) endógenos. Por tanto, se realizó un estudio para evaluar el efecto de la viscosidad de la dieta, producida por la adición de goma Guar, en la pérdida de AA endógenos recuperados al final del intestino delgado. Seis cerdos (62.0±2.5 kg peso) con cánulas en íleon terminal se utilizaron en tres periodos experimentales en un diseño en Cuadro Latino 3×3 repetido. Los tratamientos fueron: T1) dieta base semi-purificada con almidón de maíz, celulosa cristalina, sacarosa y aceite de soya; T2) dieta base más 0.5% de goma Guar; T3) dieta base más 1.0% de goma Guar. Una mezcla de vitaminas y minerales se adicionó a cada dieta para cubrir los requerimientos para cerdos en finalización. Además, se adicionó 0.2% de óxido crómico como marcador del flujo del contenido intestinal. La composición de AA de la proteína endógena, excepto por glicina, no se afectó (p0.05) por la viscosidad de la dieta; el contenido de glicina fue superior (p #8804;0.05) en los cerdos que recibieron la dieta con 1.0% de goma, comparado con los de la dieta base. La pérdida de la mayoría de los AA esenciales endógenos se redujo (p #8804;0.03) por la adición de goma a la dieta, excepto para arginina (p0.86) y valina (p0.46). Independientemente del contenido de goma Guar en la dieta, la pérdida de AA no esenciales fue dos a tres veces superior a la de los esenciales. Los resultados indican que la mayor viscosidad del alimento, causada por la adición de goma Guar a dietas, disminuye la secreción endógena de la mayoría de AA esenciales y algunos no esenciales en cerdos.