3,492 research outputs found
Identification of markers associated with bacterial blight resistance loci in cowpea (Vigna unguiculata (L.) Walp.)
No full textCowpea bacterial blight (CoBB), caused by Xanthomonas axonopodis pv. vignicola (Xav), is a worldwide major disease of cowpea [Vigna unguiculata (L.) Walp.]. Among different strategies to control the disease including cultural practices, intercropping, application of chemicals, and sowing pathogen-free seeds, planting of cowpea genotypes with resistance to the pathogen would be the most attractive option to the resource poor cowpea farmers in sub-Saharan Africa. Breeding resistance cultivars would be facilitated by marker-assisted selection (MAS). In order to identify loci with effects on resistance to this pathogen and map QTLs controlling resistance to CoBB, eleven cowpea genotypes were screened for resistance to bacterial blight using 2 virulent Xav18 and Xav19 strains isolated from Kano (Nigeria). Two cowpea genotypes Danila and Tvu7778 were identified to contrast in their responses to foliar disease expression following leaf infection with pathogen. A set of recombinant inbred lines (RILs) comprising 113 individuals derived from Danila (resistant parent) and Tvu7778 (susceptible parent) were infected with CoBB using leaf inoculation method. The experiments were conducted under greenhouse conditions (2007 and 2008) and disease severity was visually assessed using a scale where 0 = no disease and 4 = maximum susceptibility with leaf drop. A single nucleotide polymorphism (SNP) genetic map with 282 SNP markers constructed from the same RIL population was used to perform QTL analysis. Using Kruskall-Wallis and Multiple-QTL model of MapQTL 5, three QTLs, CoBB-1, CoBB-2 and CoBB-3 were identified on linkage group LG3, LG5 and LG9 respectively showing that potential resistance candidate genes cosegregated with CoBB resistance phenotypes. Two of the QTLs CoBB-1, CoBB-2 were consistently confirmed in the two experiments accounting for up to 22.1 and to 17.4% respectively for the first and second experiments. Whereas CoBB-3 was only discovered for the first experiment (2007) with less phenotypic variation explained of about 10%. Our results represent a resource for molecular marker development that can be used for marker assisted selection of bacterial blight resistance in cowpe
Optimal time of annuitization in the decumulation phase of a defined contribution pension scheme
No full textIn this paper, we consider the problem of finding the optimal time of annuitization for a retiree of a defined contribution pension scheme having the possibility of choosing her own investment and consumption strategy. We exploit the model introduced by Højgaard - Vigna (2010), who formulate the problem as a combined stochastic control and optimal stopping problem. They select a quadratic loss function that penalizes both the deviance of the running consumption rate from a desired consumption rate and the deviance of the final wealth at the time of annuitization from a desired target. We make extensive numerical investigations to address relevant issues such as optimal annuitization time, size of final annuity upon annuitization, extent of improvement when annuitization is not immediate and comparison between optimal annuitization and immediate annuitization. We find that the optimal annuitization time depends on personal factors such as the retiree's risk aversion and her subjective perception of remaining lifetime. It also depends on the financial market, via the Sharpe ratio of the risky asset. Optimal annuitization should occur a few years after retirement with high risk aversion, low Sharpe ratio and/or short remaining lifetime, and many years after retirement with low risk aversion, high Sharpe ratio and/or long remaining lifetime. Moreover, we show rigorously that with typical values of the model's parameters, a pension system where immediate annuitization is compulsory for all individuals is sub-optimal within this model. We measure the cost of sub-optimality in terms of loss of expected present value of consumption from retirement to death, and we find that the cost of sub-optimality, in relative terms, varies between 6% and 40%, depending on the risk aversion. This result gives an idea about the extent of loss in wealth suffered by a retiree who cannot choose programmed withdrawals, but is obliged to annuitize immediately on retirement all her wealth.Dened contribution pension scheme, decumulation phase, optimal annuitization time, cost of sub-optimality.
Intervista per il programma televisivo “SuperQuark”: gli interventi preventivi per l’uso e l’abuso di alcol e l’esperienza di Unplugged in Italia
No full textPresentazione delle evidenze di efficacia degli interventi preventivi per l’uso e l’abuso di alcol e l’esperienza di Unplugged in Itali
Comparação entre a absorção de vicilinas de sementes suscetíveis e resistentes do feijão-de-corda, vigna unguiculata pelo epitélio intestinal de larvas do caruncho callosobruchus maculatus e o processamento de vicilinas no corpo gorduroso após absorção
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-Graduação em Bioquímica, Florianópolis, 2013Os animais pertencentes à subfamília Bruchinae são os principais predadores das sementes de leguminosas, destacando-se pela restrição na dieta alimentar ocorrendo especificidade ao nível de gênero ou família. O caruncho do feijão-de-corda (Callosobruchus maculatus) é o maior predador de sementes de Vigna unguiculata (feijão-de-corda) tanto no campo quanto de grãos armazenados. O feijão-de-corda apresenta em sua composição uma família de proteínas multifuncionais chamadas de vicilinas (globulina 7S), possuindo uma massa molecular de aproximadamente 190 kDa. Vicilinas variantes expressas em sementes de V. unguiculata vem sendo associadas diretamente aos efeitos tóxicos causados nas larvas dos bruchideos. Aqui relata-se o valor adaptativo envolvido na absorção das vicilinas e o mecanismo da resistência associado ao C. maculatus. O genótipo (IT81D-1053) de V. unguiculata mostrou-se resistente ao bruchideo (C. maculatus), não havendo emergência de adultos no período de 90 dias, enquanto sementes suscetíveis (fradinho) apresentaram emergência média de 36,42±0,59 dias. O destino das vicilinas foi acompanhado por microscopia de fluorescência, através de cortes por congelamento (criostato), ao alimentaram-se as larvas do bruchideo com vicilina suscetível/FITC, vicilina variante/FITC e com faseolina/FITC (Phaseolus vulgaris) notando-se diferença no processo absortivo entre as dietas testadas. O epitélio intestinal das larvas alimentadas com vicilina variante/FITC e faseolina/FITC apresentou por fluorescência maior quantidade de vicilina. Por microscopia eletrônica foi possível verificar a presença da proteína suscetível (fradinho) no interior das células do epitélio intestinal das larvas de C. maculatus. Evidenciando que as vicilinas se ligam aos receptores na membrana das microvilosidades e posteriormente, são absorvidas em forma de vesículas no interior das células epiteliais do intestino médio das larvas, sendo possivelmente, mediado por processo de endocitose. As moléculas de vicilinas nas vesículas formadas no epitélio intestinal são encaminhadas ao corpo gorduroso das larvas, onde foram isoladas por ultracentrifugação em gradiente descontínuo de sacarose. Essas foram caracterizadas parcialmente com a utilização do substrato vicilina 0,1% (m/m) juntamente com os inibidores EDTA (ácido etileno diamino tetra acético), pepstatina A, PMSF (fluoreto de fenilmetilsulfonil) e E-64 (trans-epoxisuccinil 4-guanidino butano), onde a Pespatina A e PMSF inibiram o processamento da vicilina, sugerindo há uma combinação de enzimas, possivelmente proteinases serínicas e aspárticas, atuando na hidrólise da vicilina, porém não foi possível identificar qual classe mecanística é responsável pelo início do processo Abstract: The animals of the Bruchinae subfamily are the main predators of legume seeds, which are distinguished by the food diet restriction, occurring specificity on genus or family level. The cowpea beetle (Callosobruchus maculatus) is the main predator of the Vigna unguiculata seeds (cowpea) in the field and stored grains. These beans present in their composition a family of multifunctional proteins called vicilins (7S globulin), with around 190 kDa as molecular weight. Variant vicilins expressed in the seeds of V. unguiculata have been directly associated to the toxic effects caused in bruchid larvae. Here we report the adaptive value involved in the uptake of vicilin and resistance mechanisms associated with C. maculatus. The genotype (IT81D-1053) of V. unguiculata was resistant to bruchid (C. maculatus) without adult emergence in a period of 90 days, while susceptible seeds (fradinho) presented emergency of 36.42 ± 0.59 days on average. The fate of vicilin was followed by fluorescence microscopy, cutting the gel (cryostate), where bruchid the larvae are fed with vicilin susceptible/FITC, vicilin variant/FITC and phaseolin/FITC (from Phaseolus vulgaris) noticing the difference in the absorptive process. The intestinal epithelium of larvae fed on vicilin variant / FITC and phaseolin / FITC fluorescence showed a greater amount of vicilin. By using electron microscopy, it was possible to verify the presence of the susceptible vicilin (fradinho) in the cells of the intestinal epithelium of larval C. maculatus. Vicilins seem to bind to receptors in the membrane of the microvilli and subsequently are absorbed in the form of vesicles inside the cells of the epithelium of the gut of the larvae, and optionally mediated endocytosis. The vicilin molecules present in the vesicles formed in the intestinal epithelium are transferred to the fat body larvae, where they could be isolated by discontinuous sucrose gradient after ultracentrifugation. They were partially characterized using 0.1% (w / w) vicilin as the substrate in the presence or not of following inhibitors EDTA (ethylene diamine tetra acetic acid), pepstatin A, PMSF (phenylmethylsulfonyl fluoride) and E-64 (trans epoxisuccinil -4 guanidino-butane), wherein pepstatin A and PMSF inhibited the processing of vicilin, suggesting that it is a combination of enzymes, perhaps aspartic and serine proteinases, acting on the hydrolysis of vicilin. However, it was not possible to identify the mechanistic class which is responsible for initiating the process
Uso, manejo e caracterização de agricultores e de variedades locais angolanas de feijão macunde (Vigna unguiculata (L.) WALP.)
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias. Programa de Pós-Graduação em Recursos Genéticos Vegetais.O Centro Nacional de Recursos Fitogenéticos (CNRF) tem conservado em seu banco de germoplasma cerca de 2821 amostras de variedades locais de culturas alimentares, entre os quais, 313 são amostras de Vigna unguiculata (L.) Walp, conhecida em Angola por feijão macunde. Esses genótipos estão esperando por estudos de caracterização para o uso e melhoramento dessa cultura. É uma cultura amplamente distribuída no mundo, extremamente rústica, bem adaptadas a amplas condições de solo e tolerante a ampla faixa de temperatura. É fonte de proteínas de baixo custo, notadamente, para as populações carentes. O presente trabalho teve como objetivo caracterizar os produtores de feijão macunde de Angola e de variedades locais. A metodologia proposta para caracterizar as famílias produtoras desta leguminosa foi o da aplicação de um questionário semi-estruturado. Para a caracterização fenológica, morfológica e agronômica, foi realizado um ensaio no campo experimental do CNRF em Angola. Foram avaliadas 20 variedades locais de feijão macunde, em um ensaio com delineamento de blocos ao acaso, com quatro repetições. Foram adotados os descritores da cultura do feijão macunde do IBPGR (1983). Os resultados mostraram que a maior parte das famílias entrevistadas pratica agricultura de subsistência, em áreas de propriedades que variam entre um e três hectares, utilizando preferencialmente instrumentos manuais simples. O feijão macunde é cultivado em área menor de 1 hectare e geralmente consorciado com o milho, mandioca e massambala (sorgo). Em relação ao estudo de caracterização fenológica, morfológica e agronômica, os resultados mostraram que a maioria de acessos possui ciclo reprodutivo precoce com existência de diferenças significativas entre as variedades indicando a existência de grande diversidade das variedades associadas à maioria das variáveis analisadas. The National Center of Plant Genetic Resources (CNRF) conserves in its bank of germoplasm about 2821 samples of local varieties of food crops of which 313 are samples of Vigna unguiculata (L.) Walp, known in Angola as macunde. These genotypes are waiting for studies of characterization necessary before their use in breeding programs. The species is widely distributed in the world. Because of its extreme rustic it's well adapted to different soil types and tolerant the a wide range of temperatures. It is a main source of proteins for poor people. The present work aimed to characterize the producers of macunde in Angola and its local varieties. The study of the cowpea growers was based on a semi-structural questionnaire. For the characterization phenological, morphological and agronomic characteristics was done in an experimental field carried out at CNRF in Angola. Twenty local varieties of cowpea were evaluated, in the experiment, in a completely randomized blocks design, with four replications. The IBPGR (1983) cowpea descriptors were used to characteze the varieties. The results showed that most of growers interviewed practice subsistence agriculture, cultivating land, an area of one to three hectares; simple instruments are mostly used. The cowpea cultivated in the area less than one hectar generally was associated with the maize, cassava and massambala (sorghum). Most of the acesses studied showed to be precocious in relation to the reproductive cycle significant differences among varieties were also observed indicating the existence of high degree of diversity of varieties associated to most of the traits studied
Hydrogeology and groundwater quality in the quaternary alluvial deposits of the Cuneo Plain (NW Italy)
No full textEvaluating the Available Regional Groundwater Resources using the Distributed Hydrogeological Budget
No full textIn this study, several hydrogeological catchments of Central Italy have been characterized focusing the attention on the presence of areas in which, over the last two decades,the hydrological equilibrium between recharge and discharge (phenomena of marked reduction of spring discharge and progressive drawdown of groundwater levels) has been compromised
by overexploitation of groundwater resources. A GIS system has been used in order to develop the study and the homogenous distribution of the hydrological knowledge and of the existing imbalances has been performed. Characterizing elements of the research are: a) the definition
of the hydrogeological units; b) the hydrogeological survey of around a thousand water-points;
c) the monthly analysis of climatic data of numerous survey stations; d) the census and the recording of water concessions; e) the evaluation of agriculture hydro-exigency derived from
the analysis of the use of soil; f) the withdrawals defined by a statistic analysis of data. These
elements have allowed to define the Distributed Hydrogeological Budget which is a useful instrument to evaluate critical areas
Sulla declinazione della modalità di trascendere il finito. Lettera aperta a V. Melchiorre
No full textIl falso nella storia. Il ruolo della falsa coscienza e della coscienza falsa nella “scoperta” dell’America
No full textLa scoperta dell'America, raccontata dai primi esploratori, è anche una grande serie di invenzioni e falsificazioni della realtà. Motivati da interessi contingenti, dalla necessità di colpire l'immaginario dei loro contemporanei europei, o semplicemente vittime di auto-inganno per il desiderio di realizzare i propri sogni di ricchezza e di fama, autori come Colombo o Vespucci produssero un'ampia serie di falsificazioni storiche, che tuttora segnano la storia del Nuovo Mondo
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