Respuesta ecofisiológica de "Caesalpinia spinosa" (Mol.) Kuntze a condicionantes abióticos, bióticos y de manejo, como referente para la restauración y conservación del bosque de nieblas de Atiquipa (Perú)

Las lomas de Atiquipa son el oasis de nieblas más grande y mejor conservado de la costa Pacífica Sudamericana. La vegetación leñosa intercepta la niebla proveniente del océano aumentando la disponibilidad hídrica del sistema. La especie predominante en Atiquipa es la tara, Caesalpinia spinosa, leguminosa arbórea neotropical de gran valor ecológico y económico. El ecosistema de estas lomas produce múltiples bienes y servicios, pero la sobreexplotación de recursos ha provocado la deforestación reduciendo drásticamente la cobertura de bosque. La deforestación altera múltiples variables ambientales, y la regeneración natural del bosque requiere la restitución de procesos ecológicos clave que faciliten el establecimiento y desarrollo de las plantas que, para ello, deben enfrentarse a distintos condicionantes, tanto de uso y gestión, como de tipo abiótico y biótico. El objetivo general de esta tesis es valorar la respuesta ecofisiológica de tara a condicionantes que pueden beneficiar o limitar su supervivencia y desarrollo y por tanto, afectar a la capacidad de regeneración natural de los bosques de tara. En último término, el objetivo es establecer criterios de referencia que puedan ayudar en la toma de decisiones para la conservación y la restauración ecológica de las zonas degradadas del bosque de las lomas de Atiquipa y otros bosques de tara. El manejo de tara dejó una huella en la estructura de sus bosques que permitió detectar problemas de regeneración y evidencias de gestión histórica. La regeneración de tara estuvo facilitada por adultos conespecíficos y otras especies arbustivas que mejoran las condiciones microclimáticas locales y evitan herviboría. Una gestión controlada de los recursos, con limitada carga ganadera y de recolección de semillas, así como la preservación de la vegetación arbustiva, pueden ser estrategias eficaces para asegurar la regeneración y viabilidad de los bosques remanentes. La deforestación de las lomas de Atiquipa ha provocado drásticos cambios en el ecosistema relacionados con la disponibilidad hídrica y de nutrientes. Además, la deforestación alteró la estructura de las comunidades microbianas del suelo aunque la comunidad microbiana asociada a los árboles adultos de la zona deforestada fue similar a la de los de la zona conservada, y sería conveniente tenerlos en cuenta en programas de restauración como potenciales fuentes de inóculo representativas de la comunidad microbiana original. La elevada estacionalidad de los bosques de Atiquipa impone durante la época sin nieblas un doble estrés hídrico y lumínico frente al cual la tara presentó diversas estrategias de tolerancia. En condiciones de campo presentó cierre estomático, plegamiento de foliolos y bajo ratio Chl a Chl b, mientras que en condiciones controladas, presentó una disminución del potencial hídrico, cierre paulatino de estomas, y una rápida capacidad de recuperación tras la rehidratación. Además la tara mostró estrategias de fotoprotección estructural y química que contribuyeron a aliviar el estrés hídrico reduciendo la demanda evaporativa y el fotodaño. La tara mostró una estrategia más conservadora de uso de los recursos en un evento de sequía recurrente, indicando memoria de sequía. Estas respuestas frente al estrés fueron diferentes según la población de origen, siendo la procedencia más xérica, Atiquipa, la más tolerante, y deberían tenerse en cuenta en las medidas de restauración. La inoculación con bacterias autóctonas seleccionadas, tanto rizobios como bacterias PGPR, mejoró el desarrollo de las plantas, su estado fisiológico y su capacidad de tolerar el estrés abiótico. En concreto, la cepa RC5.5 Pseudomonas sp., se perfila como una buena candidata para la inoculación de plantas destinadas a la reforestación. La coreforestación de tara con Acacia macracantha podría ser una estrategia sinérgica por el carácter facilitador de acacia

Forest Restoration in a Fog Oasis: Evidence Indicates Need for Cultural Awareness in Constructing the Reference

Background: In the Peruvian Coastal Desert, an archipelago of fog oases, locally called lomas, are centers of biodiversity and of past human activity. Fog interception by a tree canopy, dominated by the legume tree tara (Caesalpinia spinosa), enables the occurrence in the Atiquipa lomas (southern Peru) of an environmental island with a diverse flora and high productivity. Although this forest provides essential services to the local population, it has suffered 90% anthropogenic reduction in area. Restoration efforts are now getting under way, including discussion as to the most appropriate reference ecosystem to use. Methodology/Principal Findings: Genetic diversity of tara was studied in the Atiquipa population and over a wide geographical and ecological range. Neither exclusive plastid haplotypes to loma formations nor clear geographical structuring of the genetic diversity was found. Photosynthetic performance and growth of seedlings naturally recruited in remnant patches of loma forest were compared with those of seedlings recruited or planted in the adjacent deforested area. Despite the greater water and nitrogen availability under tree canopy, growth of forest seedlings did not differ from that of those recruited into the deforested area, and was lower than that of planted seedlings. Tara seedlings exhibited tight stomatal control of photosynthesis, and a structural photoprotection by leaflet closure. These drought-avoiding mechanisms did not optimize seedling performance under the conditions produced by forest interception of fog moisture. Conclusions/Significance: Both weak geographic partitioning of genetic variation and lack of physiological specialization of seedlings to the forest water regime strongly suggest that tara was introduced to lomas by humans. Therefore, the most diverse fragment of lomas is the result of landscape management and resource use by pre-Columbian cultures. We argue that an appropriate reference ecosystem for ecological restoration of lomas should include sustainable agroforestry practices that emulate the outcomes of ancient uses

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

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Climate change disrupts the seasonal coupling of plant and soil microbial nutrient cycling in an alpine ecosystem

The seasonal coupling of plant and soil microbial nutrient demands is crucial for efficient ecosystem nutrient cycling and plant production, especially in strongly seasonal alpine ecosystems. Yet, how these seasonal nutrient cycling processes are modified by climate change, and what the consequences are for nutrient loss and retention in alpine ecosystems, remains unclear. Here, we explored how two pervasive climate change factors, reduced snow cover and shrub expansion, interactively modify the seasonal coupling of plant and soil microbial nitrogen (N) cycling in alpine grasslands, which are warming at double the rate of the global average. We found that the combination of reduced snow cover and shrub expansion disrupted the seasonal coupling of plant and soil N-cycling, with pronounced effects in spring (shortly after snowmelt) and autumn (at the onset of plant senescence). In combination, both climate change factors decreased plant organic N-uptake by 70 and 82%, soil microbial biomass-N by 19 and 38%, and increased soil denitrifier abundances by 253 and 136%, in spring and autumn, respectively. Shrub expansion also individually modified the seasonality of soil microbial community composition and stoichiometry, towards more N-limited conditions and slower nutrient cycling in spring and autumn. In winter, snow removal markedly reduced the fungal: bacterial biomass ratio, soil N pools, and shifted bacterial community composition. Taken together, our findings suggest that interactions between climate change factors can disrupt the temporal coupling of plant and soil microbial N-cycling processes in alpine grasslands. This could diminish the capacity of these globally widespread alpine ecosystems to retain N and support plant productivity under future climate change

Estrategias para mejorar la tolerancia a estreses abióticos de la simbiosis Rhizobium-leguminosa

[ES] Los estreses abióticos afectan negativamente al rendimiento de las leguminosas principalmente en suelos pobres en nitrógeno. Esto se debe a que la simbiosis Rhizobium-leguminosa y la fijación simbiótica de nitrógeno son altamente sensibles a dichos estreses. Es posible utilizar diferentes estrategias para dotar a las leguminosas de una mayor tolerancia a los estreses abióticos. Una de ellas es su transformación con genes codificadores de enzimas que acentúan la acumulación de osmolitos, lo que en algunos casos ha permitido aumentar la tolerancia de las plantas a estreses salino o hídrico. Otra es la de transformar plantas o rizobios para mejorar sus sistemas de defensa contra las especies reactivas de oxígeno, lo que también ha permitido aumentar su resistencia a los estreses ambientales y retrasar la senescencia de los nódulos. El estudio del papel de los factores de transcripción en las respuestas de las plantas a diversos estreses está adquiriendo gran importancia, por lo que su manipulación para la obtención de leguminosas tolerantes a estreses abióticos puede ser una estrategia de gran relevancia en un futuro próximo.[EN] Abiotic stresses adversely affect legume yield, mostly in nitrogen-deficient soils, as Rhizobium-legume symbioses and symbiotic nitrogen fixation are extremely sensitive to such stresses. Several strategies are being used to increase stress tolerance in legumes, such as transformation with genes coding for enzymes that enhance osmolyte accumulation, which in some cases has led to increased tolerance of plants to salt or water stress. Transformation of plants or rhizobia to improve their reactive oxygen species-quenching systems has also been shown to increase their resistance to environmental stresses and to delay nodule senescence. Currently, researchers are giving importance to the role of transcription factors in the responses of plants to various stresses and their manipulation may be an important strategy for obtaining legumes with increased tolerance to abiotic stresses in the coming future.El presente trabajo ha sido financiado por proyectos del Ministerio de Ciencia e Innovación, la Comunidad de Madrid, la Junta de Comunidades de Castilla-La Mancha, la Fundación Ramón Areces y la Agencia Española de Cooperación Internacional para el Desarrollo