RESUMEN
The paper is concerned with the consensus problem in a multi-agent system such that each agent has boundary constraints. Classical Olfati-Saber's consensus algorithm converges to the same value of the consensus variable, and all the agents reach the same value. These algorithms find an equality solution. However, what happens when this equality solution is out of the range of some of the agents? In this case, this solution is not adequate for the proposed problem. In this paper, we propose a new kind of algorithms called supportive consensus where some agents of the network can compensate for the lack of capacity of other agents to reach the average value, and so obtain an acceptable solution for the proposed problem. Supportive consensus finds an equity solution. In the rest of the paper, we define the supportive consensus, analyze and demonstrate the network's capacity to compensate out of boundaries agents, propose different supportive consensus algorithms, and finally, provide some simulations to show the performance of the proposed algorithms.
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Algoritmos , Inteligencia Artificial , Consenso , Modelos EstadísticosRESUMEN
INTRODUCCIÓN: Las experiencias negativas durante el parto se han asociado con desempoderamiento de la mujer, depresión postparto, trastorno por estrés postraumático y bajas tasas de lactancia maternal, entre otros. El Questionnaire for Assessing the Childbirth Experience (QACE) es una herramienta de 23 ítems útil para identificar mujeres que han tenido una mala experiencia en su proceso de parto y evitar así futuras complicaciones en embarazos posteriores o en la relación de pareja. OBJETIVO: El objetivo general consiste en adaptar el Questionnaire for Assessing the Childbirth Experience (QACE) a la población española y obtener sus características psicométricas. METODOLOGÍA: El proceso de adaptación cultural ha consistido en la traducción y retro traducción al español, evaluación de la equivalencia conceptual por un comité de jueces, evaluación de la comprensibilidad y una entrevista cognitiva a un grupo de mujeres puérperas. Las características psicométricas se han obtenido mediante el análisis factorial, los test de Kaiser-Meyer-Olkin (KMO) y Bartlett y el alfa de Cronbach. RESULTADOS: Tras el proceso de adaptación transcultural, el grupo de expertos realizó las modificaciones necesarias para conseguir una mayor compresión del cuestionario en la población española, evitar malentendidos y palabras ofensivas en la lengua de destino. Se necesitaron 138 participantes para obtener el análisis factorial. El KMO (0,838) y el test de Bartlett (p < 0,001) confirmaron la adecuación del análisis factorial y el grafico de sedimentación mostró 6 factores con un poder predictivo del 73,75% del total de la varianza. La consistencia interna se obtuvo mediante un alfa de Cronbach de 0,896. CONCLUSIONES: Los datos obtenidos en este estudio demuestran que la versión española del QACE es una herramienta válida y fiable para medir la experiencia en el nacimiento en la población española
BACKGROUND: Negative experiences during delivery are associated with women disempowerment, postpartum depression, post-traumatic stress disorder, and low breastfeeding rates. The Questionnaire for Assessing the Childbirth Experience (QACE) is a 23-item screening tool useful for discovering women with a negative experience in their birth process and avoids future complications in following pregnancies or couple's relationships. OBJECTIVE: The general objective is to adapt the Questionnaire for Assessing the Childbirth Experience (QACE) to the Spanish population and to obtain its psychometric characteristics. METHODOLOGY: The cultural adaptation process consisted of forwarding translation and back translation into Spanish, conceptual equivalence evaluation by a committee of judges, comprehensibility evaluation and cognitive interview to a postpartum group. Psychometric characteristics were obtained throughout the factorial analysis, Kaiser-Meyer-Olkin (KMO) and Bartlett's test of sphericity and Cronbach alpha level. RESULTS: After complete the adaptation process, the committee of judges made several adjustments to achieve a better comprehension in the Spanish population, avoid misunderstandings or offensive words in the target language. 138 participants were needed to calculate factor analysis. The KMO (0.838) and Bartlett test (p < 0.001) confirmed the adequacy of factor analysis and the Scree plot showed 6 factors with the predictive power of 73.75% supported total variance. Internal consistency was assured using a Cronbach α of 0.896. CONCLUSIONS: Data from this study demonstrate that the Spanish version of QACE is a valid and reliable measure of childbirth experience in the Spanish population
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Humanos , Masculino , Femenino , Adulto , Persona de Mediana Edad , Anciano , Parto/psicología , Adaptación Psicológica , 57409 , Psicometría/instrumentación , Conducta Materna/psicología , Mujeres Embarazadas/psicología , Madres/psicología , Complicaciones del Trabajo de Parto/psicología , Reproducibilidad de los Resultados , Traducciones , Comparación TransculturalRESUMEN
RESUMEN La insuficiencia velofaríngea (IVF) corresponde a cualquier defecto estructural del paladar blando o de las paredes de la faringe, caracterizado por la ausencia de tejido suficiente para lograr un cierre adecuado del mecanismo velofaríngeo durante el habla, lo que genera resonancia hipernasal y emisión nasal. En los casos de fisura con compromiso de paladar, el tratamiento para corregir la IVF puede ser quirúrgico o protésico, acompañado de intervención fonoaudiológica, pues la corrección física no elimina las alteraciones funcionales. Se presentan los resultados de habla obtenidos en un adulto hablante chileno diagnosticado con IVF secundaria a fisura palatina, rehabilitado en Fundación Gantz con prótesis de paladar obturadora y tratamiento fonoaudiológico. La evaluación mediante análisis perceptivo auditivo y nasometría evidencia una mejora del mecanismo velofaríngeo durante el habla.
ABSTRACT The velopharyngeal insufficiency (IVF) corresponds to any structural defect of the soft palate or the walls of the pharynx, where there is not enough tissue to achieve an adequate closure of the velopharyngeal mechanism during speech, generating hypernasal resonance and nasal emission. In cases of cleft palate, the treatment to correct IVF may be surgical or prosthetic, accompanied by speech therapy. The speech results obtained in a native speaker of Chilean Spanish diagnosed with IVF secondary to cleft palate, rehabilitated in Fundación Gantz with a palatal obturator (speech bulb) and speech therapy are presented. The evaluation by auditory perceptual analysis and nasometry show an improvement of the velopharyngeal mechanism during speech.
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Humanos , Masculino , Adulto , Adulto Joven , Prótesis e Implantes , Habla/fisiología , Insuficiencia Velofaríngea/etiología , Insuficiencia Velofaríngea/rehabilitación , Obturadores Palatinos , Percepción Auditiva , Fisura del Paladar/complicaciones , Resultado del TratamientoRESUMEN
Background Older age and inappropriate prescribing is related to a greater rate of emergency department visits and hospitalisations. Objective To assess the efficacy of an interprofessional collaboration programme in which a review of the medication of older patients seen in the emergency observation unit was carried out. Setting Emergency departments at four Spanish hospitals. Method Randomised, controlled study. Patients over 65 years of age presenting to the emergency department were randomised to a control or an intervention group. In the intervention group, a pharmacist reviewed the patients' chronic medication and identified any potentially inappropriate prescriptions based on the STOPP/START criteria. Each case was discussed with the emergency specialist and a recommendation to modify the treatment was sent to the general practitioner. Main outcome measure Rate of emergency visits and hospital admissions. Results The adjusted rate ratio of emergency visits and hospital admissions was 0.808 (95% CI 0.617 to 1.059) at 3 months, 0.888 (95% CI 0.696 to 1.134) at 6 months and 0.954 (95% CI 0.772 to 1.179) at 12 months. There was a statistically significant reduction at 3 months in two of the hospitals that participated in the study [adjusted rate ratio at 3 months was 0.452 (95% CI 0.222 to 0.923) in hospital 3 and 0.567 (95% CI 0.328 to 0.983) in hospital 4]. Conclusion Overall, the intervention did not reduce the number of emergency visits and hospital admissions. However, a significant effect was observed in centres were a high acceptance rate of treatment recommendations was achieved.
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Revisión de la Utilización de Medicamentos/tendencias , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/prevención & control , Servicio de Urgencia en Hospital/tendencias , Prescripción Inadecuada/tendencias , Conciliación de Medicamentos/tendencias , Farmacéuticos/tendencias , Anciano , Anciano de 80 o más Años , Revisión de la Utilización de Medicamentos/métodos , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/epidemiología , Femenino , Humanos , Prescripción Inadecuada/prevención & control , Masculino , Conciliación de Medicamentos/métodos , España/epidemiología , Resultado del TratamientoRESUMEN
La articulación compensatoria es una alteración específica del paciente con fisura labiopalatina en la cual este modifica fonemas orales de alta presión produciéndolos cerca de las cuerdas vocales. Afecta la inteligibilidad y si no se resuelve conlleva múltiples problemas. Diversos factores se han relacionado con su instauración. Aún se discute su origen fonético-fonológico. La prevención y detección temprana resultan cruciales. Objetivo: determinar la frecuencia de articulación compensatoria en menores chilenos (nacidos entre junio de 2005 y junio de 2007) con diagnóstico de fisura con compromiso velar operados en la Fundación Gantz y relacionarla con factores intervinientes. Metodología: Revisión de fichas clínicas, aplicación de exclusiones y relación de datos y análisis estadístico de algunos de ellos. Resultados: 53 por ciento de los pacientes entre cinco y siete años presentaron articulación compensatoria (29 de 55). Este grupo fue intervenido del paladar en promedio a los doce meses e ingresó a fonoaudiología a los diez meses, presentando un 83 por ciento de asociación con dificultades de lenguaje. Solo un 32 por ciento de ellos presentó insuficiencia velofaríngea. Conclusiones: se encontró una alta frecuencia de articulación compensatoria que inicialmente se relacionaría con la fisura palatina e insuficiencia velofaríngea. Entre los aspectos críticos, se destaca la edad de cierre del velo, la edad del niño y los objetivos de la estimulación prelingüística y la asociación con retrasos/trastornos de lenguaje, principalmente del nivel fonológico.
Compensatory articulation is a specific alteration of cleft-palate patients in which the production of high pressure phonemes is changed: they are produced near the vocal cords. This change affects intelligibility and when not solved it causes several problems. Different factors have been linked to this phenomenon. Its phonetic-phonological cause is still discussed and both the prevention and early detection are vital. Objective: To determine the frequency of compensatory articulation in Chilean children born between June 2005 and June 2007 with diagnosis of cleft velum and operated in Gantz Foundation and relate it to the factors that intervene it. Method: The medical records of the children were reviewed and exclusion criteria were applied. Data gathered from the medical records were statistically analysed. Results: 53 percent of the children aged between 5 and 7 presented compensatory articulation. These children were operated on at the age of about 12 months and had had in speech therapy at the age of 10 months. They presented an 83 percent of association with language difficulties. Only 32 percent of the children showed velopharyngeal insufficiency. Conclusions: It was found a high compensatory articulation frequency, which would be initially related to the cleft palate and velopharyngeal insufficiency. Among the critical aspects, it can be highlighted the age of closure of the velum, age and the pre-linguistic stimulation objectives, and association with delays/language impairment, mainly, at the phonological level.
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Humanos , Lactante , Preescolar , Fisura del Paladar/fisiopatología , Labio Leporino/fisiopatología , Trastornos de la Articulación/epidemiología , Chile , Insuficiencia Velofaríngea/epidemiología , Factores de Riesgo , Inteligibilidad del Habla , Trastornos de la Articulación/etiologíaRESUMEN
BACKGROUND: Allergy to volatile anaesthetics is extremely rare, but capable of damaging the professional career. METHODS: This article presents the case of a 60-year-old surgeon who developed a skin rash on the reverse of hands, which progressively worsened and extended to distant fold areas. Blood tests were normal but for eosinophilia and risen total IgE, with normal specific globulins and skin prick tests for common allergens. After 8 years, a malfunction in the anaesthetic gas scavenging system was found, and symptoms remitted within a week following its replacement. Repeated open application test with sevoflurane led to the appearance of the same lesions in the tested areas and in distant body folds. RESULTS: We hypothesize that the most probable mechanism for the reaction in our patient is systemic allergic contact dermatitis, which is caused by repeated systemic exposure to a hapten that reaches the skin through haematogenous transport in a sensitized patient. CONCLUSIONS: The report aims to warn about the potential aetiological relationship between exposure to inhaled anaesthetics and allergic manifestations with cutaneous symptoms.
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Anestésicos por Inhalación/toxicidad , Dermatitis Alérgica por Contacto/diagnóstico , Éteres Metílicos/toxicidad , Exposición Profesional , Dermatitis Alérgica por Contacto/sangre , Diagnóstico Diferencial , Humanos , Inmunoglobulina E/sangre , Masculino , Persona de Mediana Edad , Sevoflurano , Pruebas Cutáneas/métodos , CirujanosRESUMEN
Both polyamines and methionine derivatives are nitrogen compounds directly related to the regulation of gene expression. In silico predictions and experimental evidence suggest a cross-talk between polyamine and methionine metabolism in mammalian tissues. Since liver is the major organ that controls nitrogen metabolism of the whole organism, it is the best tissue to further test this hypothesis in vivo. In this work, we studied the effects of the chronic administration of a methionine-supplemented diet (0.5% Met in drinking water for 5 months) on the liver of mice (designated as MET-mice). Metabolic and proteomic approaches were performed and the data obtained were subjected to biocomputational analysis. Results showed that a supplemental methionine intake can indeed regulate biogenic amine metabolism in an in vivo model by multiple mechanisms including metabolic regulation and specific gene demethylation. Furthermore, putative systemic effects were investigated by molecular and cellular biology methods. Among other results, altered expression levels of multiple inflammation and cell proliferation/death balance markers were found and macrophage activation was observed. Overall, the results presented here will be of interest across a variety of biomedical disciplines, including nutrition, orphan diseases, immunology and oncology.
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Poliaminas Biogénicas/metabolismo , Hígado/metabolismo , Metionina/metabolismo , Animales , Secuencia de Bases , Metilación de ADN , Cartilla de ADN , Femenino , Inmunohistoquímica , Ratones , Ratones Endogámicos C57BL , Reacción en Cadena de la Polimerasa , Proteoma , Espectrometría de Masa por Láser de Matriz Asistida de Ionización DesorciónRESUMEN
The aim of this study was to ascertain the variations in the reproductive sex ratio (number of men to number of women) among male professional basketball players in Spain. This retrospective, cross-sectional study is based on a survey conducted in the Spanish professional basketball leagues during the season 2009-2010. A total of 172 professional basketball players completed an anonymous survey. Forty-seven of the respondents had offspring, with a total of 61 children: 70% girls and 30% boys, with a sex ratio value of 0.42. Thirty-three basketball players were Caucasian (CAU), with 44 children, nine boys and 35 girls (sex ratio = 0.26). Fourteen were black, of African heritage (AFR), with 17 children, nine boys and eight girls, (sex ratio = 1.12). Differences (P < 0.01) were found in offspring sex ratio values for all basketball players (sex ratio = 0.42) and for CAU group (sex ratio = 0.26) when compared with the general Spanish population (sex ratio = 1.06). Moreover, a significant seasonal variation was observed in CAU offspring sex ratio during the first quarter compared with the rest of the year (0.66 versus 0.12) (P < 0.03). In conclusion, a significant increase in the sex ratio value in favour of female offspring was observed in the group of CAU professional basketball players.
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Baloncesto , Razón de Masculinidad , Niño , Estudios Transversales , Femenino , Humanos , Masculino , Estudios Retrospectivos , España , Encuestas y CuestionariosRESUMEN
Introducción: La otitis media con efusión presenta una alta prevalencia en pacientes con fisura palatina, debido a una obstrucción funcional de la tuba auditiva. Dada su asociación con hipoacusia y una baja tendencia de resolución espontánea, existe controversia sobre la necesidad de instalar tubos de ventilación en estos pacientes. Objetivo: Comparar resultados anatómicos y audiológicos de dos estrategias de tratamiento. Material y método: Estudio de cohorte histórica en niños de 8 a 11 años con fisura velopalatina operada. La otitis con efusión de un grupo se trató con tubos de ventilación, mientras otro grupo tuvo un manejo conservador. La presencia de alteraciones timpánicas e hipoacusia se compararon entre ambos grupos mediante Xi cuadrado y test de Fischer. Resultados: Cincuenta y seis pacientes fueron reclutados, 24 en estrategia quirúrgica y 32 en conservadora. Todos los pacientes presentan una evaluación fonoaudiológica normal. Existe mayor frecuencia de retracción timpánica, perforación timpánica e hipoacusia de conducción en aquellos niños sometidos a una estrategia agresiva de tratamiento. Discusión: Existen mayores alteraciones timpánicas e hipoacusia en los pacientes sometidos a una estrategia de tratamiento quirúrgica, por lo que parece prudente realizar una evaluación individual y determinar la necesidad de cirugía de acuerdo a cada paciente.
Introduction: Otitis media with effusion (OME) is a frequent finding in patients with cleft palate due to a functional obstruction of the Eustachian tube. Because of its association with hearing loss and low rate of spontaneous resolution the use of ventilation tubes as treatment appears as beneficial The clinical and audiological consequences of this conduct areinot well established. Aim: To compare anatómical and audiologics results with two strategies of treatment. Material ana method: Historical cohort study of children from 8 to 10 years, with cleft palate, surgically corrected, and with OME. One group was treated with ventilation tubes, and an expectant management was carried out with the other group. The following parameters were compared by Xi-square test and Fischer: tympanic membrane state, presence of compiications and hearing level. Results: Fifty six patients were admitted, 24 in surgical management and 32 in conservative. Every child had a cleft palate corrected without velopharyngeal insufficiency It was found a higher frequency of tympanic membrane retraction, tympanic membrane perforation and hearing loss in the case groups were found. Discusion: We found a greater presence of tympanic alterations and hearing disorders in patients subjected to ventilation tubes as treatment of OME. It seems prudent to evalúate the surgical alternative individually according to each patient characteristic.
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Humanos , Niño , Fisura del Paladar/complicaciones , Otitis Media con Derrame/etiología , Otitis Media con Derrame/terapia , Pérdida Auditiva/etiología , Ventilación del Oído MedioRESUMEN
The aim of this work is the evaluation of metal phytostabilisation potential of Lupinus luteus inoculated with Bradyrhizobium sp. 750 and heavy metal resistant PGPRs (plant-growth promoting rhizobacteria), for in situ reclamation of multi-metal contaminated soil after a mine spill. Yellow lupines accumulated heavy metals mainly in roots (Cu, Cd and especially Pb were poorly translocated to shoots). This indicates a potential use of this plant in metal phytostabilisation. Furthermore, As accumulation was undetectable. On the other hand, zinc accumulation was 10-100 times higher than all other metals, both in roots and in shoots. Inoculation with Bradyrhizobium sp. 750 increased both biomass and nitrogen content, indicating that nitrogen fixation was effective in soils with moderate levels of contamination. Co-inoculation of lupines with a consortium of metal resistant PGPR (including Bradyrhizobium sp., Pseudomonas sp. and Ochrobactrum cytisi) produced an additional improvement of plant biomass. At the same time, a decrease in metal accumulation was observed, both in shoots and roots, which could be due to a protective effect exerted on plant rhizosphere. Our results indicate the usefulness of L. luteus inoculated with a bacterial consortium of metal resistant PGPRs as a method for in situ reclamation of metal polluted soils.
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Biodegradación Ambiental , Lupinus/metabolismo , Metales Pesados/farmacocinética , Rhizobium/crecimiento & desarrollo , Contaminantes del Suelo/farmacocinética , Liberación de Peligros Químicos , Descontaminación/métodos , Lupinus/crecimiento & desarrollo , Lupinus/microbiología , Minería , Fijación del Nitrógeno , Raíces de Plantas/metabolismo , Rhizobium/fisiologíaRESUMEN
BACKGROUND Polymorphisms C677T and A1298C of the MTHFR gene have been implicated in fetal viability. In this study, we determined the allele and genotype frequencies of these polymorphisms in different populations, including spontaneous abortion (SA) fetal tissues, with the objective of evaluating their impact on fetal viability. METHODS 342 samples of fetal tissues, selected from SA occurring during the 1980s, 230 samples from subjects born in the 1980s and a third set of samples from 204 subjects born in the 1950s, were genotyped by using TaqMan probes. RESULTS The wild CC genotype of the C677T polymorphism showed a strong protective effect against abortion (0.03 in SA versus 0.47 in 1950s and 0.43 in 1980s) (P < 0.0001). Genotypes of three mutations in the combinations of polymorphisms for C677T and A1298C showed a very low frequency in the living population; however, the three mutations genotypes were over expressed in the SA group (0.02 in 1950s; 0.03 in 1980s and 0.17 in SA) (P < 0.0001). Samples with four mutations (n = 2) were found only in the SA group. CONCLUSIONS There is no linkage disequilibrium between C667T and A1298C polymorphisms. Fetal viability is directly related to the CC genotype as a protector while the three and four mutation MTHFR genotypes appear to be a determinant on fetal non-viability and SA.
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Aborto Espontáneo/genética , Metilenotetrahidrofolato Reductasa (NADPH2)/genética , Polimorfismo Genético , Aborto Espontáneo/enzimología , Feto/enzimología , Predisposición Genética a la Enfermedad , Genotipo , HumanosRESUMEN
No disponible
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Humanos , Enfermedades de la Tiroides/diagnóstico , Pruebas de Función de la Tiroides/métodos , Tiroxina/sangre , Tirotropina/sangre , Sensibilidad y Especificidad , Valores de ReferenciaRESUMEN
To characterize the macroscopic behavior of Diesel sprays and to validate and extend for current high-pressure injection systems the correlations existent in the literature, it is necessary to determine the spray geometry accurately, at least in terms of spray tip penetration and cone angle. These parameters are measured by analyzing Diesel spray images and are highly sensitive to the correct edge determination. An algorithm for segmentation of color images based on a likelihood ratio test is presented. This algorithm is compared with others available in the literature and has been validated, even for adverse experimental conditions. The experimental facilities, optical layouts, and image-processing algorithms are described.
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We report a model system for plasmid transfer analysis using the regulated lambda phage right promoter, lPR, fused to luc and lucOR as reporter genes. We have demonstrated that the systems cI857-lPR::luc and cI857-lPR::lucOR are temperature-inducible in Escherichia coli but not in other Gram-negative bacteria analyzed, enabling detection of luminescence when plasmids were mobilized from E. coli to those Gram-negative backgrounds. Using light for the detection, we have observed plasmid transfer from E. coli harboring RK2 and R388 derived plasmids to Pseudomonas putida KT2440 (co-introduced with donors) and to indigenous microorganisms, in vitro and in nonsterile soil microcosms. The importance of nutrients for an efficient plasmid transfer in nonsterile soil microcosms has been confirmed. When plasmid transfer experiments were carried out into nonsterile soil microcosms, significant populations of indigenous transconjugants arose. This system provides efficient marker genes and avoids the use of antibiotics for the selection of transconjugants.
RESUMEN
The production of hydrolytic enzymes from external mycelia associated with roots and colonized soybean roots (Glycine max L.) inoculated with different arbuscular-mycorrhizal (AM) fungi of the genus GLOMUS:, and the possible relationship between these activities and the capacity of the AM fungi to colonize plant roots was studied. There were differences in root colonization and plant growth between the GLOMUS: strains, and also between two isolates of G. mosseae. Hydrolytic activities in the root and external mycelia associated with roots differed in the AM fungi tested. Correlations were only found between the endoxyloglucanase activity of the external mycelia associated with roots of the AM fungi tested and the percentage root colonization or plant growth. However, hydrolytic activities of roots colonized by the different endophytes correlated with those of external mycelia. The hydrolytic activities were not qualitatively different because the endoxyloglucanase from AM colonized roots and the external mycelia did not show a high degree of polymorphism in the different species of fungus tested. The possible role of the hydrolytic activity of external hyphae of AM fungi was discussed as a factor affecting fungal ability to colonize the root and influence plant growth.
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Enzimas/metabolismo , Hongos/fisiología , Glycine max/microbiología , Raíces de Plantas/microbiología , Hongos/enzimología , HidrólisisRESUMEN
Polygalacturonase (PG) is one of the most important enzymes associated with plant cell wall degradation. It has been proposed to participate in the early steps of the Rhizobium-legume interaction. We have identified two classes of cDNA fragments corresponding to two classes of PG genes in the Medicago genome. One of this class, represented by E2 in M. truncatula and Pl1 in M. sativa, seems to be related to previously characterized plant PG genes expressed in pollen. We have isolated the genomic clone containing the entire gene corresponding to the second class (E3). We showed that MsPG3 is a single gene in the Medicago genome coding for PG. By reverse transcription-PCR, MsPG3 expression was detected in roots 1 day after Rhizobium inoculation. The early induction of the MsPG3, as also seen by in situ hybridization experiments, supports its involvement in the early stages of the Rhizobium-legume infection process. In addition, by analyzing the expression of a MsPG3 promoter-gus construct in Vicia hirsuta-transgenic root nodules, we showed that MsPG3 was expressed in all cells of nodule primordia and in the cells of the invasion zone. By Northern blot, MsPG3 transcripts are not detected in various Medicago tissues, indicating that the function of this gene is related closely to symbiosis. Thus, our results strongly suggest the involvement of MsPG3 gene during meristem formation and/or in the infection process, probably by facilitating cell wall rearrangement, penetration of the bacteria through the root hair wall, or infection thread formation and release of bacteria in plant cells. MsPG3 represents a class of PG genes, distinct from the pollen-specific genes, and it is the first pectic encoded enzyme demonstrated to be involved in Rhizobium-legume symbiosis.
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Medicago sativa/genética , Poligalacturonasa/genética , Sinorhizobium meliloti/fisiología , Secuencia de Aminoácidos , Cartilla de ADN , ADN Complementario , Regulación Bacteriana de la Expresión Génica , Regulación Enzimológica de la Expresión Génica , Regulación de la Expresión Génica de las Plantas , Hibridación in Situ , Solanum lycopersicum/genética , Medicago sativa/enzimología , Medicago sativa/microbiología , Datos de Secuencia MolecularRESUMEN
The Rhizobium leguminosarum bv trifolii exoB gene has been isolated by heterologous complementation of an exoB mutant of R. meliloti. We have cloned a chromosomal DNA fragment from the R. leguminosarum bv trifolii genome that contains an open reading frame of 981 bp showing 80% identity at the amino acid level to the UDP-glucose 4-epimerase of R. meliloti. This enzyme produces UDP-galactose, the donor of galactosyl residues for the lipid-linked oligosaccharide repeat units of various heteropolysaccharides of rhizobia. An R. leguminosarum bv trifolii exoB disruption mutant differed from the wild type in the structure of both the acidic exopolysaccharide and the lipopolysaccharide. The acidic exopolysaccharide made by our wild-type strain is similar to the Type 2 exopolysaccharide made by other R. leguminosarum bv trifolii wild types. The exopolysaccharide made by the exoB mutant lacked the galactose residue and the substitutions attached to it. The exoB mutant induced the development of abnormal root nodules and was almost completely unable to invade plant cells. Our results stress the importance of exoB in the Rhizobium-plant interaction.
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Fabaceae/microbiología , Plantas Medicinales , Polisacáridos Bacterianos/genética , Rhizobium leguminosarum/fisiología , Simbiosis/genética , UDPglucosa 4-Epimerasa/genética , Secuencia de Carbohidratos , Clonación Molecular , Genes Bacterianos , Datos de Secuencia Molecular , Mutación , Polisacáridos Bacterianos/química , Polisacáridos Bacterianos/metabolismo , Mapeo Restrictivo , Homología de Secuencia de Ácido Nucleico , Sinorhizobium meliloti/fisiología , UDPglucosa 4-Epimerasa/metabolismoRESUMEN
The extracellular and surface polysaccharides produced by Rhizobium species constitute a composite macromolecular interface between the bacterial cell and its environment. Several of these polysaccharides are involved in the complex series of interactions leading to the establishment of an effective Rhizobium-legume symbiosis. Extracellular heteropolysaccharides (EPSs) are found in culture supernatants, while capsular polysaccharides adhere to the cell surface. Cyclic (1-2)-ß-d glucan is a periplasmic oligosaccharide that has also been found in the culture supernatants of some strains. The lipopolysaccharides (LPSs), which form part of the outer membrane and contain the O-somatic antigens, comprise the other major group of extracellular polysaccharides. In this review we will describe the major Rhizobium extracellular structures and their role in symbiosis with leguminous plants.