23,037 research outputs found

    Revisão taxonómica do género Calendula L. (Asteraceae - Calenduleae) na Península Ibérica e Marrocos

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    The genus Calendula L. (Asteraceae - Calenduleae) includes, depending on the author, 10 to 25 species, distributed mainly in the Mediterranean basin. The taxonomy of this genus is considered to be extremely difficult, due to a great morphological variability, doubtfull relevance of some of the characters used to distinguish its species (e.g. the life form: annual or perennial; the habit: erect or diffuse, shape of the leaves, indumentum, relative size of the capitula and colour of disc or ray florets, achene morphology), but also due to the hybridization and polyploidization. Despite the numerous studies that have been published, no agreement on the classification and characters used to discriminate between taxa has been reached. A taxonomic study of the genus Calendula was conducted for the Iberian Peninsula and Morocco, aiming at (1) access the morphological variability between and within taxa, (2) confirm the chromosome numbers, (3) increase the nuclear DNA content estimations, (4) re-evaluate taxa delimitations and circumscription, and (5) reassess, and redefine, the descriptions and characters useful to distinguish taxa. In order to achieve a satisfying taxonomic core, extensive fieldwork, detailed morphometric analysis, chorological, karyological and genome size studies were conducted. For the Iberian Peninsula, four species were recognized, including nine subspecies (between these two new subspecies were described). For Morocco, including some taxa from Algeria and Tunisia 13 species were recognized (two new species and a nomenclatural change), including 15 subspecies (among these eight new subspecies were described). To corroborate the results obtained and to evaluate the evolutionary relationships among taxa, phylogenetic studies using molecular methods, such as ITS, microsatellites or other molecular markers, should be used.O g√©nero Calendula L. (Asteraceae - Calenduleae) inclui, dependendo do autor, 10 a 25 esp√©cies, distribu√≠das essencialmente na bacia do Mediterr√Ęneo. A taxonomia deste g√©nero √© considerada extremamente dif√≠cil, devido √† grande variabilidade morfol√≥gica, discutivel relev√Ęncia de alguns dos caracteres utilizados para distinguir suas esp√©cies (por exemplo, a forma de vida: anual ou perene, o h√°bito: erecto ou difuso, a forma das folhas, o indumento, o tamanho e a cor dos cap√≠tulos e a morfologia dos aqu√©nios), mas tamb√©m devido √† hibridiza√ß√£o e poliploidiza√ß√£o. Apesar dos in√ļmeros estudos que foram publicados, n√£o foi alcan√ßado um acordo sobre a classifica√ß√£o e os caracteres utilizados para discriminar as suas esp√©cies. Um estudo taxon√≥mico do g√©nero Calendula foi realizado para a Pen√≠nsula Ib√©rica e Marrocos, com o objectivo de (1) verificar a variabilidade morfol√≥gica, (2) confirmar o n√ļmero de cromossomas, (3) aumentar as estimativas de conte√ļdo em ADN, (4) reavaliar a delimita√ß√£o e a circunscri√ß√£o dos taxa, e (5) reavaliar e redefinir as descri√ß√Ķes e caracteres √ļteis para os distinguir. Para alcan√ßar uma robust√™s taxon√≥mica satisfat√≥ria, foram realizados extensos trabalhos de campo, an√°lise morfom√©trica detalhada, abordagens corol√≥gicas, cariol√≥gicas e quanto ao conte√ļdo em ADN. Para a Pen√≠nsula Ib√©rica, quatro esp√©cies foram reconhecidas, incluindo nove subesp√©cies (entre essas duas novas subesp√©cies foram descritas). Para Marrocos, incluindo alguns taxa da Argelia e Tunisia, foram reconhecidas 13 esp√©cies (duas novas e uma mudan√ßa nomenclatural), incluindo 15 subesp√©cies (entre essas oito novas subesp√©cies foram descritas). Para corroborar os resultados obtidos e avaliar as rela√ß√Ķes evolutivas e filogen√©ticas entre os taxa, estudos que utilizem diferentes m√©todos moleculares, tais como ITS, microsat√©lites ou outros marcadores moleculares, devem ser utilizados.Apoio financeiro do Laborat√≥rio Associado CESAM - Centro de Estudos do Ambiente e do Mar (AMB/50017) financiado por fundos nacionais atrav√©s da FCT/MCTES e cofinanciado pelo FEDER (POCI-01-0145-FEDER-007638), no √Ęmbito do Acordo de Parceria PT2020, e Compete 2020Programa Doutoral em Biologi

    Differential responses in some quinoa genotypes of a consortium of beneficial endophytic bacteria against bacterial leaf spot disease

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    Many effective plant-microbe interactions lead to biological changes that can stimulate plant growth and production. This study evaluated the effect of the interaction between quinoa (Chenopodium quinoa Willd.) and endophytic bacterial strains on differential responses under biotic stress. Four strains of endophytic bacteria were used to inoculate three quinoa genotypes. Endophytic bacteria, isolated from the endosphere of healthy genotypes of quinoa plants, were used to evaluate their biocontrol activity against Pseudomonas syringae on quinoa plants, which causes leaf spot disease, depending on some different parameters. Quinoa genotype plants were treated with four treatments: pathogenic bacteria only (T1), internal bacteria only (T2), pathogenic bacteria + endogenous bacteria (T3), and untreated as the control (T4). The results indicated that there was a significant difference between chlorophyll content index of infected plants without bioagent (untreated) compared to plants bio-inoculated with endophytic bacteria. The highest mean disease incidence was on the plants without bacterial inoculum (90, 80, and 100%) for quinoa genotypes G1, G2, and G3, respectively. The results showed that there were significant differences in the weight of grains/plant, as the value ranged from 8.1 to 13.3‚ÄČg when treated with pathogens (T1) compared to the treatment with pathogens and endogenous bacteria (T3), which ranged from 11.7 to 18.6‚ÄČg/plant. Decreases in total aromatic amino acids appeared due to the pathogen infection, by 6.3, 22.8, and 24.1% (compared to the control) in G1, G2, and G3, respectively. On the other hand, genotype G3 showed the highest response in the levels of total aromatic and total neutral amino acids. The endophytic strains promoted quinoa seedling growth mainly by improving nutrient efficiency. This improvement could not be explained by their ability to induce the production of amino acids, showing that complex interactions might be associated with enhancement of quinoa seedling performance by endophytic bacteria. The endophytic bacterial strains were able to reduce the severity of bacterial leaf spot disease by 30, 40, and 50% in quinoa genotypes G1, G2, and G3, respectively, recording significant differences compared to the negative control. The results indicated that, G1 genotype was superior in different performance indicators (pathogen tolerance index, yield injury %, superiority measure and relative performance) for grain weight/plant under pathogen infection condition when treated with endophyte bacteria. Based on this study, these bacterial strains can be used as a biotechnology tool in quinoa seedling production and biocontrol to diminish the severity of bacterial leaf spot disease

    Environmental surveillance for Salmonella Typhi as a tool to estimate the incidence of typhoid fever in low-income populations.

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    Background: The World Health Organisation recommends prioritised use of recently prequalified typhoid conjugate vaccines in countries with the highest incidence of typhoid fever. However, representative typhoid surveillance data are lacking in many low-income countries because of the costs and challenges of diagnostic clinical microbiology. Environmental surveillance (ES) of Salmonella Typhi in sewage and wastewater using molecular methods may offer a low-cost alternative, but its performance in comparison with clinical surveillance has not been assessed. Methods: We developed a harmonised protocol for typhoid ES and its implementation in communities in India and Malawi where it will be compared with findings from hospital-based surveillance for typhoid fever. The protocol includes methods for ES site selection based on geospatial analysis, grab and trap sample collection at sewage and wastewater sites, and laboratory methods for sample processing, concentration and quantitative polymerase chain reaction (PCR) to detect Salmonella Typhi. The optimal locations for ES sites based on digital elevation models and mapping of sewage and river networks are described for each community and their suitability confirmed through field investigation. We will compare the prevalence and abundance of Salmonella Typhi in ES samples collected each month over a 12-month period to the incidence of blood culture confirmed typhoid cases recorded at referral hospitals serving the study areas. Conclusions: If environmental detection of Salmonella Typhi correlates with the incidence of typhoid fever estimated through clinical surveillance, typhoid ES may be a powerful and low-cost tool to estimate the local burden of typhoid fever and support the introduction of typhoid conjugate vaccines. Typhoid ES could also allow the impact of vaccination to be assessed and rapidly identify circulation of drug resistant strains

    Database for validation of thermo-hydro-chemo-mechanical behaviour in bentonites

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    This paper presents a database of thermo-hydro-chemo-mechanical tests on bentonites, which has been named ‚ÄúBento_DB4THCM‚ÄĚ. After a comprehensive literature review, a set of experimental tests have been compiled. The experimental data are used to perform validation exercises for numerical codes to simulate the coupled thermo-hydro-mechanical and geochemical behaviour of bentonites. The database contains the information required for the simulation of each experimental test solving a boundary value problem. The validation exercises cover a wide range of clays, including the best-known bentonites (MX-80, FEBEX, GMZ) as well as others. The results collected in this database are from free swelling, swelling under load, swelling pressure and squeezing tests. The database is attached as Supplementary material.En este art√≠culo se presenta una base de datos de ensayos termo-hidro-quimio-mec√°nicos sobre bentonitas, a la que se ha denominado ‚ÄúBento_DB4THCM‚ÄĚ. Despu√©s de una revisi√≥n exhaustiva de la literatura, se ha compilado un conjunto de pruebas experimentales. Los datos experimentales se utilizan para realizar ejercicios de validaci√≥n de c√≥digos num√©ricos para simular el comportamiento termohidromec√°nico y geoqu√≠mico acoplado de las bentonitas. La base de datos contiene la informaci√≥n requerida para la simulaci√≥n de cada prueba experimental que resuelve un problema de valor l√≠mite. Los ejercicios de validaci√≥n cubren una amplia gama de arcillas, incluidas las bentonitas m√°s conocidas (MX-80, FEBEX, GMZ) entre otras. Los resultados recopilados en esta base de datos provienen de pruebas de hinchamiento libre, hinchamiento bajo carga, presi√≥n de hinchamiento y compresi√≥n. La base de datos se adjunta como material complementario

    Biological effects of sub-lethal doses of glyphosate and AMPA on cardiac myoblasts

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    Introduction: Glyphosate is the active compound of different non-selective herbicides, being the most used agriculture pesticide worldwide. Glyphosate and AMPA (one of its main metabolites) are common pollutants of water, soil, and food sources such as crops. They can be detected in biological samples from both exposed workers and general population. Despite glyphosate acts as inhibitor of the shikimate pathway, present only in plants and some microorganisms, its safety in mammals is still debated. Acute glyphosate intoxications are correlated to cardiovascular/neuronal damages, but little is known about the effects of the chronic exposure.Methods: We evaluated the direct biological effects of different concentrations of pure glyphosate/AMPA on a rat-derived cell line of cardiomyoblasts (H9c2) in acute (1‚Äď2 h) or sub-chronic (24‚Äď48 h) settings. We analyzed cell viability/morphology, ROS production and mitochondrial dynamics.Results: Acute exposure to high doses (above 10 mM) of glyphosate and AMPA triggers immediate cytotoxic effects: reduction in cell viability, increased ROS production, morphological alterations and mitochondrial function. When exposed to lower glyphosate concentrations (1 őľM‚ÄĒ1 mM), H9c2 cells showed only a slight variation in cell viability and ROS production, while mitochondrial dynamic was unvaried. Moreover, the phenotype was completely restored after 48 h of treatment. Surprisingly, the sub-chronic (48 h) treatment with low concentrations (1 őľM‚ÄĒ1 mM) of AMPA led to a late cytotoxic response, reflected in a reduction in H9c2 viability.Conclusion: The comprehension of the extent of human exposure to these molecules remains pivotal to have a better critical view of the available data

    Ecological successions throughout the desiccation of Tirez lagoon (Spain) as an astrobiological time-analog for wet-to-dry transitions on Mars

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    Tirez was a small and seasonal endorheic athalassohaline lagoon that was located in central Spain. In recent years, the lagoon has totally dried out, offering for the first time the opportunity to analyze its desiccation process as a ‚Äútime-analog‚ÄĚ to similar events occurred in paleolakes with varying salinity during the wet-to-dry transition on early Mars. On the martian cratered highlands, an early period of water ponding within enclosed basins evolved to a complete desiccation of the lakes, leading to deposition of evaporitic sequences during the Noachian and into the Late Hesperian. As Tirez also underwent a process of desiccation, here we describe (i) the microbial ecology of Tirez when the lagoon was still active 20 years ago, with prokaryotes adapted to extreme saline conditions; (ii) the composition of the microbial community in the dried lake sediments today, in many case groups that thrive in sediments of extreme environments; and (iii) the molecular and isotopic analysis of the lipid biomarkers that can be recovered from the sediments today. We discuss the implications of these results to better understanding the ecology of possible Martian microbial communities during the wet-to-dry transition at the end of the Hesperian, and how they may inform about research strategies to search for possible biomarkers in Mars after all the water was los

    Re-prioritizing climate services for agriculture: Insights from Bangladesh

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    Considerable progress has been made in establishing climate service capabilities over the last few decades, but the gap between the resulting services and national needs remains large. Using climate services for agriculture in Bangladesh as a case study example, we highlight mismatches between local needs on the one hand, and international initiatives that have focused largely on prediction on the other, and we make suggestions for addressing such mismatches in similar settings. To achieve greater benefit at the national level, there should be a stronger focus on addressing important preliminaries for building services. These preliminaries include the identification of priorities, the definition of responsibilities and expectations, the development of climate services skills, and the construction of a high-quality and easily usable national climate record. Once appropriate institutional, human resources and data infrastructure are in place, the implementation of a climate monitoring and watch system would form a more logical basis for initial climate service implementation than attempting to promote sub-seasonal to seasonal climate forecasting, especially when and where the inherent predictability is limited at best. When and where forecasting at these scales is viable, efforts should focus on defining and predicting high-impact events important for decision making, rather than on simple seasonal aggregates that often correlate poorly with outcomes. Some such forecasts may be more skillful than the 3- to 4-month seasonal aggregates that have become the internationally adopted standard. By establishing a firm foundation for climate services within National Meteorological Services, there is a greater chance that individual climate service development initiatives will be sustainable after their respective project lifetimes

    Seed certification and maize, rice and cowpea productivity in Nigeria: An insight based on nationally representative farm household data and seed company location data

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    Despite the potential importance of seed quality to agricultural productivity growth, many governments in sub-Saharan Africa lack the capacity to expand quality assurance systems even where there is expressed interest. This study aims to evidence the value of quality assurance systems with an analysis of efforts to produce and distribute certified seed in Nigeria. We assess the associations between quantities of certified seeds produced and spatial variations in production locations proxied by headquarter locations of seed companies producing certified seeds, on the one hand, with spatial variations in the use of certified seed, yields, and output at the farm level, on the other hand. Our analysis covers three crops that are important to food security in Nigeria: maize, rice, and cowpea. Our analysis integrates information on seed quantities produced and locations of seed companies with nationally representative panel data from a survey of farm households and spatially explicit rainfall and temperature data. We find a positive relationship between certified seed production in proximity to farm households and farm-level use of certified seeds, yields, and output, although this effect is diminishing at the margin. These diminishing marginal effects may be partly due to two factors. First, the yield gains from certified seeds tend to vary considerably within each state, suggesting that either quality issues persist in the seed supply chain or farmers are not using complementary inputs or appropriate management techniques when using quality seed. Second, it may be that as certified seed becomes more available to farmers, its use spreads from higher-return farms to lower-return farms, thereby diminishing the gains on the extensive margin. Although more rigorous assessments of causal effects and cost-effectiveness are needed to validate these findings, these results are consistent with the hypothesis that there are diminishing returns to seed quality assurance. Policymakers, regulators, and seed providers may benefit from identifying optimal, crop-specific target quantities or rates for certified seed production rather than aiming for certification of all seed produced in a market
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