Capacidad de fijación de nitrógeno de estirpes autóctonas de Mesorhizobium spp. en simbiosis con dos poblaciones mejoradas de Lotus glaber (Miller)

Se evaluó la capacidad de nodulación y fijación de nitrógeno de tres estirpes de Mesorhizobium sp. que fueron aislados de los suelos de la depresión del río Salado, Provincia de Buenos Aires. Estas cepas se inocularon en dos poblaciones mejoradas de Lotus glaber FA2 y FA7. Las cepas autóctonas en simbiosis con las dos poblaciones de Lotus nodularon y fijaron mas nitrógeno que las plantas testigo no inoculadas y que los testigos inoculados con la cepa control USDA3471. Las poblaciones de Lotus glaber difirieron en su habilidad para desarrollar en presencia de cantidades limitantes de nitrógeno. Se concluyó que las bacterias autóctonas, tienen una alta capacidad de fijación de nitrógeno y por lo tanto constituyen una fuente para la selección de cepas en la formulación de inoculantes comerciales.We evaluated the ability of Mesorhizobium strains that were isolated from the soils of the Salado River Basin in the province of Buenos Aires. Two populations of Lotus glaber, FA2 and FA7, were inoculated with three rizobia isolates L10, L15 and L22. The autoctonous strains nodulated and fixed more nitrogen than uninoculated (negative) and USDA3471 inoculated (positive) control plants. The populations of Lotus glaber differed in their ability to grow in the presence of low levels of available nitrogen. We concluded that the soils of the Salado river basin host bacteria with high nitrogen fixing potential that may be used in inoculant production

Construction of a Sinorhizobium meliloti strain carrying a stable and non-transmissible chromosomal single copy of the green fluorescent protein GFP-P64L/S65T

A single copy of the green fluorescent protein (GFP)-encoding gene gfp-P64L/S65T under the control of the constitutive nptII promoter was introduced in a neutral region of the Sinorhizobium meliloti chromosome, between the genes recA and alaS. Within the same chromosomal region downstream of gfp-P64L/S65T a tetracycline (Tc) resistant cassette was also inserted. Both markers were very stable during at least 40 bacterial generations without any selective pressure. Similarly, the gfp-Tc cassette was stable and functional in all rhizobia that were recovered from alfalfa nodules. The GFP-associated fluorescence derived from the (single copy) chromosomal gfp-P64L/S65T allowed detection of rhizobia during the colonisation of the root, infection thread formation, and nodule development. The gfp-Tc rhizobia showed indistinguishable phenotypes for nodulation, competitiveness, and nitrogen-fixation from the parental strain. The labelling system described here can be used for the stable fluorescent tagging of S. meliloti strains allowing their detection in biologically complex soil environments.Facultad de Ciencias ExactasInstituto de Biotecnologia y Biologia Molecula

Construction of a Sinorhizobium meliloti strain carrying a stable and non-transmissible chromosomal single copy of the green fluorescent protein GFP-P64L/S65T

A single copy of the green fluorescent protein (GFP)-encoding gene gfp-P64L/S65T under the control of the constitutive nptII promoter was introduced in a neutral region of the Sinorhizobium meliloti chromosome, between the genes recA and alaS. Within the same chromosomal region downstream of gfp-P64L/S65T a tetracycline (Tc) resistant cassette was also inserted. Both markers were very stable during at least 40 bacterial generations without any selective pressure. Similarly, the gfp-Tc cassette was stable and functional in all rhizobia that were recovered from alfalfa nodules. The GFP-associated fluorescence derived from the (single copy) chromosomal gfp-P64L/S65T allowed detection of rhizobia during the colonisation of the root, infection thread formation, and nodule development. The gfp-Tc rhizobia showed indistinguishable phenotypes for nodulation, competitiveness, and nitrogen-fixation from the parental strain. The labelling system described here can be used for the stable fluorescent tagging of S. meliloti strains allowing their detection in biologically complex soil environments.Facultad de Ciencias ExactasInstituto de Biotecnologia y Biologia Molecula

Caracterización simbiótica de rizobios noduladores de alfalfa aislados en suelos ácidos de Argentina

En comunicaciones anteriores hemos descripto la estrategia utilizada para el aislamiento de rizobios noduladores de alfalfa de suelos ácidos locales, su caracterización genética preliminar, y el estudio de propiedades de tolerancia a la acidez en medios artificiales en condiciones de laboratorio (SAIB 1996). Dicho análisis permitió diferenciar claramente dos grupos de rizobios noduladores de alfalfa distintas respecto al rango de hospedadores, capacidad fijadora de nitrógeno, y tolerancia a la acidez. Las cepas de S. meliloíi (Sme) resultaron levemente ácido tolerantes (pH 6,0) pero eficientes fijadoras de nitrógeno. Contrariamente, aislamientos de R. spp. genéticamente relacionados a la cepa previamente descripta Orí 91 resultaron muy ácido tolerantes (pH 5,0) pero ineficientes. En el presente trabajo hemos analizado en detalle las propiedades de nodulación y competitividad a diferentes pHs, de cepas representativas de cada uno de los grupos de rizobios previamente caracterizados.Digitalizado en SEDICI-CIC Digital

The early-life exposome modulates the effect of polymorphic inversions on DNA methylation

Polymorphic genomic inversions are chromosomal variants with intrinsic variability that play important roles in evolution, environmental adaptation, and complex traits. We investigated the DNA methylation patterns of three common human inversions, at 8p23.1, 16p11.2, and 17q21.31 in 1,009 blood samples from children from the Human Early Life Exposome (HELIX) project and in 39 prenatal heart tissue samples. We found inversion-state specific methylation patterns within and nearby flanking each inversion region in both datasets. Additionally, numerous inversion-exposure interactions on methylation levels were identified from early-life exposome data comprising 64 exposures. For instance, children homozygous at inv-8p23.1 and higher meat intake were more susceptible to TDH hypermethylation (P¿=¿3.8¿×¿10-22); being the inversion, exposure, and gene known risk factors for adult obesity. Inv-8p23.1 associated hypermethylation of GATA4 was also detected across numerous exposures. Our data suggests that the pleiotropic influence of inversions during development and lifetime could be substantially mediated by allele-specific methylation patterns which can be modulated by the exposome.Peer ReviewedPostprint (published version

Selección de “indicadores microbiológicos de calidad del suelo” como tópico generativo para la enseñanza de Microbiología Agrícola en la FCAyF

Se presenta una innovación en el área de Microbiología Agrícola de las Carreras de Ingeniería Agronómica y Forestal, propiciando el “uso de indicadores microbiológicos de calidad del suelo” como “tópico generativo” en el marco de “la enseñanza para la comprensión”. Con la aplicación de esta metodología, se busca concientizar a los alumnos sobre la importancia de la conservación del recurso suelo y su biodiversidad, así como ponerlos en contacto con problemáticas hipotéticas de su futura actividad laboral. Se definieron las Metas de Comprensión, seleccionando los indicadores microbiológicos: determinación del recuento de flora total y grupos funcionales (celulolíticos, amonificadores, nitrificadores), actividad global del suelo empleando técnicas como la evaluación de la respiración y la deshidrogenasa. En base a los datos analizados se observa que la selección de este tópico generativo resultó adecuada para el desarrollo e integración de los contenidos del curso y permitió fomentar en los alumnos una actitud participativa en el proceso de enseñanza-aprendizaje.Eje temático 2: Los cambios e innovaciones en los procesos de formación\na - Alternativas didácticas y experiencias de renovación de la enseñanz

Health promotion in primary care: How should we intervene? A qualitative study involving both physicians and patients

<p>Abstract</p> <p>Background</p> <p>The effects of tobacco, physical exercise, diet, and alcohol consumption on morbidity and mortality underline the importance of health promotion and prevention (HPP) at the primary health care (PHC) level. Likewise, the deficiencies when putting such policies into practice and assessing their effectiveness are also widely recognised. The objectives of this research were: a) to gain an in-depth understanding of general practitioners' (GPs) and patients' perceptions about HPP in PHC, and b) to define the areas that could be improved in future interventions.</p> <p>Methods</p> <p>Qualitative methodology focussed on the field of health services research. Information was generated on the basis of two GP-based and two patient-based discussion groups, all of which had previously participated in two interventions concerning healthy lifestyle promotion (tobacco and physical exercise). Transcripts and field notes were analysed on the basis of a sociological discourse-analysis model. The results were validated by triangulation between researchers.</p> <p>Results</p> <p>GPs and patients' discourses about HPP in PHC were different in priorities and contents. An overall explanatory framework was designed to gain a better understanding of the meaning of GP-patient interactions related to HPP, and to show the main trends that emerged from their discourses. GPs linked their perceptions of HPP to their working conditions and experience in health services. The dimensions in this case involved the orientation of interventions, the goal of actions, and the evaluation of results. For patients, habits were mainly related to ways of life particularly influenced by close contexts. Health conceptions, their role as individuals, and the orientation of their demands were the most important dimensions in patients' sphere.</p> <p>Conclusions</p> <p>HPP activities in PHC need to be understood and assessed in the context of their interaction with the conditioning trends in health services and patients' social micro-contexts. On the basis of the explanatory framework, three development lines are proposed: the incorporation of new methodological approaches according to the complexity of HPP in PHC; the openness of habit change policies beyond the medical services; and the effective commitments in the medium to long term by the health services themselves at the policy management level.</p

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality