24,313 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
Nutraceutical antioxidant potential and polyphenolic profiles of the Zambian market classes of bambara groundnuts (Vigna subterranea L. Verdc) and common beans (Phaseolus vulgaris L.)
No full textIncludes abstract.Includes bibliographical references.There is a growing interest in legumes and legume based foods because of the health claims associated with their consumption. The aim of the current study was to explore the nutraceutical potential of bambara groundnuts (Vigna subterranea L. Verdc) and common beans (Phaseolus vulgaris L.) commonly grown in Zambia based on the antioxidant properties and phenolic phytochemical profiles. Two market classes of bambara groundnuts (red and brown) and four of common beans (red, grey mottled, brown and white) were screened in raw dry form. Effects of cooking and sprouting on the antioxidant activities and phenolic phytochemicals of the promising market classes were assessed. The study employed in vitro antioxidant assays (DPPH and FRAP) to screen for antioxidant properties, HPLC-PDA-ESI-MS and Folin Ciocalteu assay to screen for phenolic phytochemical profiles
Nouveau bureau de l'AFHMT
No full textSuite à la réunion du conseil d'administration de notre association le 30 novembre dernier, le conseil d'administration a accueilli trois nouveaux membres : Camille Fauroux, Matthieu Scherman et Alessandro Stanziani. Lors de sa première réunion, ce conseil d'administration a élu un nouveau bureau : Corine Maitte, présidente Camille Fauroux, vice-présidente Xavier Vigna, secrétaire Isabelle Moret-Lespinet, vice-secrétaire Laure Machu, trésorièr
The construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Séminaire : Frontières ouvrières
No full textAnimé par Eric Geerkens, Nicolas Hatzfeld, Isabelle Lespinet-Moret, Xavier Vigna programme 2018-2019 Pour sa deuxième année sur ce thème, le séminaire se propose d’explorer les délimitations du monde ouvrier qui sont proposées au cours des XIXe et XXe siècles, aux configurations bien différentes. Il s’agit donc de scruter les variations que connaissent les contours des mondes ouvriers et de leurs périphéries, tels qu’ils sont dessinés par différents acteurs. Il s’agit particulièrement ..
Della gioia di trovare un maestro - Piccola "postilla non-scientifica, ma anche non-conclusiva" per Carmelo Vigna
No full textCome piccolo gesto di gratitudine e riconoscimento, il breve testo vuole ricordare e discutere i ricchissimi impulsi che il pensiero di Carmelo Vigna e in particolare la sua “etica del riconoscimento” e la critica della “vita spettacolare” hanno dato agli studi dell’autrice su Kierkegaard, sui modelli antropologici nella letteratura tedesca tra illuminismo e romanticismo, sulle basi etiche del linguaggio e sul rapporto tra estetica e etica. Facile dunque leggere le lezioni ricevute come realizzazione ideale dell’agire di un “vero maestro” che sa esercitare in pieno la difficile arte maieutica di cui Kierkegaard parla nelle sue riflessioni sulla comunicazione “indiretta”: Rendere l’altro libero, in questo si manifesta il senso più intimo e la dignità più profonda del compito di chi insegna
Language Change and SA-OT: The case of sentential negation
No full textSimulated Annealing for Optimality Theory (SA-OT) updates Optimality Theory by adding a model of performance to a theory of linguistic competence. Our aim is to show that SA-OT can contribute to language change simulations. Performance "errors" are considered to be one of the causes of variation and change. We have chosen to model the evolution of sentential negation (SN). The descriptive background adopts Jespersen's Cycle, according to which the evolution of sentential negation follows three main stages (1. pre-verbal, 2. discontinuous, and 3. post-verbal). Therefore, we advance a novel model for SN, based on SA-OT. It reproduces the three pure and the two observed mixed stages, whereas it correctly predicts the lack of an intermediate stage between 3 and 1. The success of the approach corroborates the computational, performance-based approach to the data. Finally, we employ the iterated learning paradigm to reproduce historical changes in a "simulated corpus study". This enterprise turns out to be more difficult than one would naively believe.Appeared open access as: Computational Linguistics in the Netherlands Journal (CLIN), vol. 1 (2011), pp. 21-40, and is available at http://www.clinjournal.org/sites/default/files/Lopopolo.pdfA. Lopopolo and Biró, T., “Language Change and SA-OT. The case of sentential negation”, Computational Linguistics in the Netherlands Journal, vol. 1, pp. 21-40, 2011.Peer Reviewe
Fungal species associated with Vigna unguiculata (L.) Walp (Cowpea) seed from parts of Enugu State, Nigeria
No full textA study was conducted on fungal organisms associated with Cowpea (Vigna unguiculata (L.) Walp) seeds obtained from three Local Government Areas in Enugu state, namely Nsukka, Igbo-eze and Udenu L. G. A. In each L. G. A., the seeds were collected from two different towns: Lejja and Orba for Nsukka L. G. A;Aku and Ukehe for Igbo-eze L. G. A and lastly Ezimo and Ubollo for Udenu L. G. A. Standard Blotter Method and Agar method were used for the isolation of Fungi. Cowpea seeds from different locations had varying levels of infestation with fungi. Aspergillus niger Van Tieghem, Botryodiplodia theobromae (Pat) Novel, Fusarium oxysporum Schlecht and Rhizopus stolonifer Ehrenb ex Link were isolated from both blotter and agar methods. Botryodiplodia theobromae had the highest mean occurrence (42.37%) followed by Fusarium oxysporum (30.02%), Aspergillus niger (21.99%) and lastly, Rhizopus stolonifer (10.15%). The occurrences of fungi isolate according to the location were observed with Fusarium oxysporum occurring most in Lejja and Aku by 24 isolates and 18 isolates respectively. In Orba, Aspergillus niger occurred most by 19 isolates. In Ukehe, Ezimo and Obimo, Botryodiplodia theobromae occurred most by 21 isolates, 19 isolates and 11 isolates respectively. Seed pathogens cause reduction in cooking quality, nutritive values, and decrease germinability of seeds and total decay. Cowpea serve as an important food in Africa. There is need for regular seed testing and adequate seed treatment so as to ensure that growers produce healthy plant produceKeywords: Vigna unguiculata (L.) Walp seed, fungi, Isolation, Pathogenecit
Biodiversity and Geographic Distribution of Rhizobia Nodulating With Vigna minima
No full textVigna minima is a climbing annual plant widely distributed in barren wilderness, grass land, and shrub bush of China and other countries such as Japan. However, the rhizobia nodulating with this plant has never been systematically studied. In order to reveal the biodiversity of nodulating rhizobia symbiosis with V. minima, a total of 874 rhizobium isolates were obtained from root nodules of the plant spread in 11 sampling sites of Shandong Peninsula, China, and they were designated as 41 haplotypes in the genus Bradyrhizobium based upon recA sequence analyses. By multilocus sequence analysis (MLSA) of five housekeeping genes (dnaK, glnII, gyrB, recA, and rpoB), the 41 strains representing different recA haplotypes were classified into nine defined species and nine novel genospecies. Bradyrhizobium elkanii, Bradyrhizobium ferriligni, and Bradyrhizobium pachyrhizi were the predominant and universally distributed groups. The phylogeny of symbiotic genes of nodC and nifH showed similar topology and phylogenetic relationships, in which all the representative strains were classified into two clades grouped with strains nodulating with Vigna spp., demonstrating that Vigna spp. shared common nodulating groups in the natural environment. All the representative strains formed nodules with V. minima in a nodulation test performed in green house conditions. The correlation between V. minima nodulating rhizobia and soil characteristics analyzed by CANOCO indicates that available nitrogen, total nitrogen, and organic carbon in the soil samples were the main factors affecting the distribution of rhizobia isolated in this study. This study systematically uncovered the biodiversity and distribution characteristics of V. minima nodulating rhizobia for the first time, which provided novel information for the formation of the corresponding rhizobium community
Breeding drought tolerant cowpea: constraints, accomplishments, and future prospects
No full textThis review presents an overview of accomplishments on different aspects of cowpea breeding for drought tolerance. Furthermore it provides options to enhance the genetic potential of the crop by minimizing yield loss due to drought stress. Recent efforts have focused on the genetic dissection of drought tolerance through identification of markers defining quantitative trait loci (QTL) with effects on specific traits related to drought tolerance. Others have studied the relationship of the drought response and yield components, morphological traits and physiological parameters. To our knowledge, QTLs with effects on drought tolerance have not yet been identified in cowpea. The main reason is that very few researchers are working on drought tolerance in cowpea. Some other reasons might be related to the complex nature of the drought stress response, and partly to the difficulties associated with reliable and reproducible measurements of a single trait linked to specific molecular markers to be used for marker assisted breeding. Despite the fact that extensive research has been conducted on the screening aspects for drought tolerance in cowpea only very few¿like the `wooden box¿ technique¿have been successfully used to select parental genotypes exhibiting different mechanisms of drought tolerance. Field and pot testing of these genotypes demonstrated a close correspondence between drought tolerance at seedling and reproductive stages. Some researchers selected a variety of candidate genes and used differential screening methods to identify cDNAs from genes that may underlie different drought tolerance pathways in cowpea. Reverse genetic analysis still needs to be done to confirm the functions of these genes in cowpea. Understanding the genetics of drought tolerance and identification of DNA markers linked to QTLs, with a clear path towards localizing chromosomal regions or candidate genes involved in drought tolerance will help cowpea breeders to develop improved varieties that combine drought tolerance with other desired traits using marker assisted selection
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