Utilización de árboles fijadores de nitrógeno Escallonia pendula y Alnus acuminata para la recuperación de suelos erosionados.

Los suelos erosionados aumentan día a día con el mal uso de la tierra tanto en las áreas urbanas como rurales de nuestro país, la explotación minera principalmente en la provincia de Sogamoso, la presencia de zonas de alta pendiente, las malas técnicas agrícolas y ganaderas son algunos factores erosivos en esta región. La utilización de árboles fijadores de nitrógeno (AFN) como mangle (Escallonia pendula) y aliso (Alnus acuminata) permite la recuperación de suelos degradados y erosionados, permitiendo así la estabilización de zonas de altas pendientes, arenosas e inundables; al estar asociados con microorganismos fijadores de nitrógeno del suelo de los géneros Rhizobium y Frankia respectivamente, y algunas clases de hongos. Esta simbiosis permite la fijación del nitrógeno atmosférico, aumento de la absorción del agua y nutrientes. El mangle y el aliso, se asocian muy bien con otro tipo de cultivos de gramíneas como el kikuyo (Pennisetum clandestinum) tubérculos como la papa (Solanum tuberosum) y cultivos de frutas como el lulo (Solanun quitoense) mejorando su producción; al igual que su asociación con bacterias fijadoras de nitrógeno y la producción de hojarasca, mejora las características físicas y químicas del suelo. En esta monografía se citan los estudios realizados en algunas regiones de Colombia, de los arboles fijadores de nitrógeno mangle (Escallonia pendula) y aliso (Alnus acuminata); y algunas visitas a predios que ya están iniciando el proceso de mejoramiento de suelos con estas especies arbóreas, con el ánimo de ilustrar al lector en el mejoramiento de los suelos erosionados y la posible utilización de los AFN (Alnus acuminata) y (Escallonia pendula) en sus predios.The eroded soils increase day by day with the misuse of the land in both urban and rural areas of our country, mining mainly in the province of Sogamoso, the area of high slope, poor agricultural and livestock techniques are some erosive factors in this region. The use of nitrogen fixing trees (AFN) such as mangrove (Escallonia pendula) and alder (Alnus acuminata) allows the recovery of degraded and eroded soils, thus allowing the stabilization of areas of high slopes, sandy and flooded; to be associated with soil nitrogen fixing microorganisms of the genera Rhizobium and Frankia respectively, and some kinds of fungi. This symbiosis allows the fixation of atmospheric nitrogen, increasing the absorption of water and nutrients. The mangrove and the alder, are very well associated with other types of crops of the genus of grasses such as the kikuyo (Pennisetum clandestinum) tubers such as potatoes (Solanum tuberosum) and fruit crops such as lulo (Solanun quitoense) improving its production; as well as its association with nitrogen-fixing bacteria and the production of litter, improves the physical and chemical characteristics of the soil. In this monograph the studies carried out in some regions of Colombia, of mangrove nitrogen fixing trees (Escallonia pendula) and alder trees (Alnus acuminata) are cited; and some visits to farms that are already starting the process of soil improvement with these tree species, with the aim of illustrating the reader in the improvement of eroded soils and the possible use of the AFN (Alnus acuminata) and (Escallonia pendula) in their properties

Age-related immune response heterogeneity to SARS-CoV-2 vaccine BNT162b2

Abstract: Although two-dose mRNA vaccination provides excellent protection against SARS-CoV-2, there is little information about vaccine efficacy against variants of concern (VOC) in individuals above eighty years of age1. Here we analysed immune responses following vaccination with the BNT162b2 mRNA vaccine2 in elderly participants and younger healthcare workers. Serum neutralization and levels of binding IgG or IgA after the first vaccine dose were lower in older individuals, with a marked drop in participants over eighty years old. Sera from participants above eighty showed lower neutralization potency against the B.1.1.7 (Alpha), B.1.351 (Beta) and P.1. (Gamma) VOC than against the wild-type virus and were more likely to lack any neutralization against VOC following the first dose. However, following the second dose, neutralization against VOC was detectable regardless of age. The frequency of SARS-CoV-2 spike-specific memory B cells was higher in elderly responders (whose serum showed neutralization activity) than in non-responders after the first dose. Elderly participants showed a clear reduction in somatic hypermutation of class-switched cells. The production of interferon-γ and interleukin-2 by SARS-CoV-2 spike-specific T cells was lower in older participants, and both cytokines were secreted primarily by CD4 T cells. We conclude that the elderly are a high-risk population and that specific measures to boost vaccine responses in this population are warranted, particularly where variants of concern are circulating