Genetic relationship of cowpea (Vigna unguiculata) varieties from Senegal based on SSR markers.

Genetic diversity and phylogenetic relationships among 22 local cowpea (Vigna unguiculata) varieties and inbred lines collected throughout Senegal were evaluated using simple sequence repeat molecular markers. A set of 49 primer combinations were developed from cowpea genomic/expressed sequence tags and evaluated for their ability to detect polymorphisms among the various cowpea genotypes. Forty-four primer combinations detected polymorphisms, with the remaining five primer sets failing to yield PCR amplification products. From one to 16 alleles were found among the informative primer combinations; their frequencies ranged from 0.60 to 0.95 (mean = 0.79). The genetic diversity of the sample varied from 0.08 to 0.42 (mean = 0.28). The polymorphic information content ranged from 0.08 to 0.33 (mean = 0.23). The local varieties clustered in the same group, except 53-3, 58-53, and 58-57; while Ndoute yellow pods, Ndoute violet pods and Baye Ngagne were in the second group. The photosensitive varieties (Ndoute yellow pods and Ndoute violet pods) were closely clustered in the second group and so were inbred line Mouride and local cultivar 58-57, which is also one of the parents for inbred line Mouride. These molecular markers could be used for selection and identification of elite varieties for cowpea improvement and germplasm management in Senegal.

Genetic variation of Casuarina equisetifolia subsp equisetifolia and C. equisetifolia subsp incana populations on the northern coast of Senegal.

The genetic variation of 70 individual samples of Casuarina equisetifolia (L. Johnson) subsp equisetifolia and C. equisetifolia subsp incana growing along the northern coast of Senegal was analyzed with RAPD markers. Of the 160 primers tested, five were chosen; they generated 1396 reproducible bands and 61 polymorphic bands that were scored. This result showed a narrow genetic variation among (4.36%) and within (5.90%) C. equisetifolia subsp equisetifolia and C. equisetifolia subsp incana plantation sites. The genetic variation at each site revealed a high degree of polymorphism in Potou (5.90%) and low diversity in Retba (3.06%). In the dendrogram analyses, each sampling site was formed by two main groups. Similar results were found for the dendrograms based on the RAPD data gathered from the five different sites. These dendrograms revealed several polytomies in one of the subgroups, suggesting replication of the same specimens in different sites along the Senegalese coast. The RAPD data support the hypothesis that these populations are of the same provenance, subject to hybridization and inbreeding depression.

Phylogenetic analyses of symbiotic genes and characterization of functional traits of Mesorhizobium spp. strains associated with the promiscuous species Acacia seyal Del.

AIMS: To assess the phenotypic, symbiotic and genotypic diversity scope of Mesorhizobium spp. strains associated with Acacia seyal (Del.) isolated from different agro-ecological zones in Senegal, and uses of susceptible microbial inoculum in a reafforestation process. METHODS AND RESULTS: A polyphasic approach including phenotypic and genotypic techniques was used to study the diversity and their relationships with other biovars and species of rhizobia. The geographical origins of the strains have limited effect on their phylogenetic and phenotypic classification. Nodulation tests indicated promiscuity of the strains studied, because they were capable of nodulating six woody legume species (Acacia auriculiformis, Acacia senegal, A. seyal, Acacia tortilis ssp. raddiana, Leucaena leucocephala and Prosopis juliflora). Sequencing and phylogenetic analyses of nodA, nodC and nifH genes pointed out that in contrast to nodA gene, the phylogenies of nodC and nifH genes were not consistent with that of 16S rRNA, indicating that these genes of the A. seyal-nodulating rhizobia might have different origins. Microbial inoculation on nonsterile soil had significant effect on the nodules number and the growth of the seedlings, indicating that these strains of rhizobia might be used as inoculum. CONCLUSIONS: The results indicated that A. seyal is a nonselective host that can establish effective symbiosis with Mesorhizobium spp. strains from diverse genomic backgrounds and that the selected A. seyal-nodulating rhizobia could enhance plant growth. SIGNIFICANCE AND IMPACT OF THE STUDY: These results showed the important role that A. seyal could play in the improvement of reafforestation process as a promiscuous host, which can establish effective symbiosis with rhizobia from diverse genomic backgrounds.

Phenotypic and genotypic characteristics of Acacia senegal (L.) Willd. root-nodulating bacteria isolated from soils in the dryland part of Senegal.

AIMS: We characterized phenotypically and genotypically root-nodulating bacteria associated with Acacia senegal (L.) Willd. isolated from the soils surrounding A. senegal trees in the dry land area of Senegal. METHODS AND RESULTS: The phenotypical and genotypical characterizations we carried out showed a high diversity of A. senegal root-nodulating bacteria. Phenotypic patterns showed adaptations of the rhizobial strains to many environmental stresses such as heat, drought, and salinity. Twelve molecular groups were distinguished by profiles obtained using polymerase chain reaction/restriction fragment length polymorphism techniques from intergenic spacer region rDNA. The highest genetic diversity was found around the A. senegal rhizosphere. Therefore, A. senegal seemed to have a positive influence on occurrence and genotypical diversity of rhizobial populations. Rhizobial isolates obtained in this study belonged phylogenetically to the genera Mesorhizobium and Rhizobium. CONCLUSIONS: Our results provided information about the genetic diversity of the rhizobial strains associated with A. senegal and suggested the adaptability of natural rhizobial populations to major ecological environmental stress within these soil environments. SIGNIFICANCE AND IMPACT OF THE STUDY: These results suggested a potential selection of compatible and well adapted strains under stress conditions as inoculants for successful A. senegal growth in arid lands.

Hairy root nodulation of Casuarina glauca: a system for the study of symbiotic gene expression in an actinorhizal tree.

The purpose of this study was to establish a fast system for producing transgenic actinorhizal root nodules of Casuarina glauca. Agrobacterium rhizogenes strain A4RS carrying the p35S-gusA-int gene construct was used to induce hairy roots on hypocotyls of 3-week-old C. glauca seedlings. Three weeks after wounding, the original root system was excised, and composite plants consisting of transgenic roots on untransformed shoots were transferred to test tubes to be inoculated with Frankia. The actinorhizal nodules formed on transformed roots had the nitrogenase activity and morphology of untransformed nodules. beta-Glucuronidase (GUS) activity was examined in transgenic roots and nodules by fluorometric and histochemical assays. The results indicate that transgenic nodules generated with this root transformation system could facilitate the molecular study of symbiotic nitrogen fixation in actinorhizal trees.

Chimiotherapie des cancers du col de l'uterus au stade IV a vesical a l'Institut Curie de Dakar

Les cancers du col de l'uterus au stade IV ne relevent plus de la combinaison standard radio-chirurgicale. Aussi dans notre contexte marque par les difficultes de tous ordres pour correctement appliquer la chimiotherapie; nous avons pense opportun de retracer notre experience dans l'utilisation de moyen therapeutique dans les cancers du col uterin classes IVa vesical a Dakar. Sur 91 dossiers retenus; 80 ont concerne la mise en oeuvre de la combinaison chimiotherapie et radio-therapie selon diverses modalites. Les resultats enregistres dans la pratique de cette modalite nous poussent a proposer la procedure chimiotherapie neoadjuvante suivie de radiochimiotherapie dans notre contexte en l'absence de curietherapie pour ameliorer la survie

Developpement d'une matrice ethylcellulose/eudragitr pour la liberation controlee et continue de l'insuline

But : Le diabete de type I est une maladie chronique necessitant des prises repetees d'insuline toute une vie durant par voie parenterale. Ce mode d'administration en plus d'etre traumatisant peut poser un probleme d'observance du traitement chez le patient. Dans le souci de pallier ces difficultes; nous avons envisage le developpement d'une matrice ethylcellulose/eudragitr susceptible de faciliter la mise au point d'un systeme therapeutique transdermique de liberation controlee (STTLC) de l'insuline. Materiel et methode : Comme principe actif nous avons utilise de l'insuline humaine anhydre Actrapidr HM des laboratoires Novo Nordisk; les excipients sont l'ethylcellulose; les Eudragitr RS 100 et le butylphtalate. Nous avons elabore deux matrices Ethylcellulose/Eudragit dans les rapports 1 : 1 et 2 : 1 dans lesquels sont incorporees differentes proportions d'insuline. Resultats : L'etude de la liberation de l'insuline en milieu tampon phosphate a pH 7;4 a montre une liberation continue avec des profils fortement dependants du rapport Ethylcellulose/Eudragit et de la charge initiale en insuline. Conclusion : Cette etude a montre que la matrice Ethylcellulose/Eudragit se prete a la mise au point d'un systeme a liberation controlee d'insuline. Ceci nous permet d'envisager pour la poursuite de notre travail l'association de cette matrice avec d'autres elements pour la realisation d'un STTLC de l'insuline