Les robes des taurins dans les peintures de la Tassili-n-Ajjer (Algérie) : polymorphisme ou fantaisies ?

The comparison of five hundred rock paintings in the Tassili-n-Ajjer with present-day animal husbandry shows that the polymorphic coats of neolithic cattle were most of them depicted realistically. In other words, few are imagined. We thus dispose of new spatial and chronological markers for pluri-millennium cattle coat evolution patterns. This observation raises questions in relation not only to the status of painters, but also to husbandry strategies and social relations between 4000 and 2000 BCE.La comparaison de cinq cent peintures rupestres de taurins réalisées dans la Tassili-n-Ajjer avec les animaux d'élevage actuels, révèle que les robes polymorphes du bétail dessinées au Néolithique ont été pour la plupart traitées avec fidélité, et que rares sont celles imaginées. De nouveaux jalons spatio-temporels concernant l'évolution plurimillénaire du pelage chez les taurins sont ainsi posés. Ce constat permet aussi de s'interroger sur le statut des peintres et sur les stratégies d'élevage et les relations sociales entre 4000 et 2000 av. J.-C

La préparation et le passage du recensement du Soudan 2008

Les opérations de comptage du 5e recensement de la population du Soudan viennent de s'achever. Elles se devaient d'aller à la rencontre des quelques 38 millions d'habitants du plus étendu des pays d'Afrique avec un questionnaire unique. Elles étaient conduites par deux institutions statistiques, l'une au Nord et l'autre au Sud. Le principe du recensement  a été scellé dans les accords de paix qui ont mis fin à la guerre civile entre le Sud et le Nord Soudan en 2005. Les résultats sont extrêmement attendus puisqu'ils doivent servir de base pour déterminer le partage des revenus pétroliers, préparer les élections législatives de 2009 et le référendum d'auto-détermination du Sud en 2011. Autant d'enjeux, les multiples conflits identitaires et pour l'accès, le contrôle et la redistribution des ressources à toutes les échelles et sur toutes les marges du Soudan font du recensement un catalyseur et finalement un révélateur des limites tragiques de la gouvernance ethnocratique.The Fith population census enumeration operations have just been achieved. They have to meet the 38 millions inhabitants of the largest countries of Africa with a unique questionnaire shared by two statistical institutions, one in the North and a second for the South. The census is a milestone of the peace agreement of 2005 that put an end to the civil war between the Nord and the South. The census results are extremely waited as they will determine the petrol dividend sharing, the parlement election of 2009 and the independence referendum of 2011. So much stakes, identity and ressources access, control and redistribution conflicts at all scales and in every sudanese margin are pushing the census to catalyse and finally reveal the tragical limits of an ethnocratic governance

Développement d'outils pour l'étude in vivo de la régulation post-transcriptionnelle chez Caenorhabditis elegans

La régulation de l expression des gènes est fondamentale pour coordonner la synthèse, l assemblage et la localisation des complexes macromoléculaires dans les cellules. Cette expression est régulée à divers niveaux. Elle commence dans le noyau où les facteurs de transcription se lient à des séquences spécifiques d ADN et recrutent les ARN polymérases pour la synthèse des ARN. La régulation à ce niveau est dite transcriptionnelle. Les protéines de liaison à l ARN s associent avec l ARN en cours de synthèse et opèrent divers modifications comme l addition d une coiffe en 5 , l épissage, l édition et la poly-adénylation en 3 . Les transcrits sont alors exportés vers le cytoplasme où ils vont être adressés et stockés dans des régions subcellulaires. Les ARNm s assemblent avec des facteurs de traduction et les ribosomes pour initier la synthèse protéique de manière contrôlée. Enfin, les ARNm sont dégradés. Les régulations qui touchent chacune de ces étapes sont dites post-transcriptionnelles. Le développement récent d outils d analyse à l échelle génomique ont permis une meilleure compréhension globale des programmes de régulation des gènes au niveau transcriptionnel. Cependant, l architecture globale des systèmes qui régulent les étapes post-transcriptionnelles d expression des gènes est encore peu connue. Un tel système de régulation post-transcriptionnelle doit être contrôlé par des centaines de protéines de liaison à l ARN et de microARN (miARN) encodés dans les génomes eucaryotes. C est pourquoi il est important de disposer d outils et de plateformes adaptés à l étude de cette régulation à l échelle génomique. Dans cette thèse, nous nous sommes intéressés à deux programmes de la régulation post-transcriptionnelle chez Caenorhabditis elegans : l épissage alternatif et la régulation par les miARN. Nous avons utilisés des vers rapporteurs de l épissage alternatif exprimant la double fluorescence GFP et RFP afin d étudier l architecture de cette régulation et l identification ou la validation des facteurs en trans et des éléments en cis par génétique classique en utilisant la mutagenèse aléatoire, l automatisation du crible grâce au COPAS biosorter et le séquençage des génomes entiers. Nous avons également modifiés en profondeur le module ReFlx du cytomètre en flux adapté aux organismes de grande taille (COPAS Biosorter) afin d éliminer les problèmes de contamination et diviser par sept le temps nécessaire au traitement dans le but de mener une étude de génétique inverse à haut débit par ARN interférence. Nous avons enfin générer des lignées fluorescentes bi-colores pour étudier la régulation dépendante de la région 3 UTR grâce aux microARN.The regulation of gene expression is fundamental to coordinate the synthesis, assembly and localization of macromolecular complexes in cells. This expression is regulated at various levels. It begins in the nucleus where transcription factors bind to specific DNA sequences and recruit RNA polymerases to synthesize RNA. Regulation at this level is called transcriptional. RNA binding proteins associate with RNA during synthesis and operate various modifications such as the addition of a 5' cap, splicing, editing and polyadenylation at the 3'. The transcripts are then exported to the cytoplasm where they will be sent to subcellular regions and stored. mRNA are then associated with translation factors and ribosomes to initiate protein synthesis in a controlled manner. Finally, mRNAs are degraded. Regulations that affect each of these steps are called post-transcriptional regulations. The recent tools developments for genomic scale analysis have allowed a better overall understanding of gene regulation programs at the transcriptional level. However, the overall architecture of systems that regulate post-transcriptional steps of gene expression is still misunderstood. Such a system of post-transcriptional regulation must be controlled by hundreds of RNA binding proteins and microRNA (miRNA) encoded in eukaryotic genomes. This is why it is important to have tools and platforms suited to the study of the post-transcriptional regulation on a genomic scale. During this thesis, we have focused our work on two post-transcriptional regulation programs in Caenorhabditis elegans : alternative splicing and miRNAs regulation. We used GFP and RFP double fluorescent alternative splicing reporter lines to study the architecture of this regulation and to identify trans factors and cis-elements by using forward genetics, random mutagenesis, automated screen through COPAS biosorter and whole genome sequencing. We also extensively modified the ReFlx module of the COPAS to fix carry over problems and divide by seven the time required for processing in order to conduct a High throughput reverse genetic study using RNA interference. We finally generate bi-color fluorescent lines to study 3 'UTR regulation mediated by microRNAs.BORDEAUX2-Bib. électronique (335229905) / SudocSudocFranceF

GaHV-2 ICP22 protein is expressed from a bicistronic transcript regulated by three GaHV-2 microRNAs

International audienceHerpesviruses have a lifecycle consisting of successive lytic, latent and reactivation phases. Only three infected cell proteins (ICPs) have been described for the oncogenic Marek's disease virus (or Gallid herpes virus 2, GaHV-2): ICP4, ICP22 and ICP27. We focus here on ICP22, confirming its cytoplasmic location and showing that ICP22 is expressed during productive phases of the lifecycle, via a bicistronic transcript encompassing the US10 gene. We also identified the unique promoter controlling ICP22 expression, and its core promoter, containing functional responsive elements including E-box, ETS-1 and GATA elements involved in ICP22 transactivation. ICP22 gene expression was weakly regulated by DNA methylation and activated by ICP4 or ICP27 proteins. We also investigated the function of GaHV-2 ICP22. We found that this protein repressed transcription from its own promoter and from those of IE ICP4 and ICP27, and the late gK promoter. Finally, we investigated posttranscriptional ICP22 regulation by GaHV-2 microRNAs. We found that mdv1-miR-M5-3p and -M1-5p downregulated ICP22 mRNA expression during latency, whereas, unexpectedly, mdv1-miR-M4-5p upregulated the expression of the protein ICP22, indicating a tight regulation of ICP22 expression by microRNAs

SCAN domain-containing 2 gene (SCAND2) is a novel nuclear protein derived from the zinc finger family by exon shuffling. Gene 289:1–6

Abstract The SCAN domain is a recently recognized protein domain that characterizes a subfamily of the Krüppel-like zinc finger proteins. We have previously described a novel SCAN domain-containing 2 gene (SCAND2) that does not belong to the zinc finger family. We report structural and sequence analyzes of all known members of the SCAN family and use these data to illustrate a model of gene family evolution. Most of the SCAN containing genes share common gene organization features that support the proposed origin for SCAND2 by disruption of an ancestral SCAN-zinc finger gene by a retroposition event and subsequent exon shuffling.

Incorporating Evolutionary Information and Functional Domains for Identifying RNA Splicing Factors in Humans

Regulation of pre-mRNA splicing is achieved through the interaction of RNA sequence elements and a variety of RNA-splicing related proteins (splicing factors). The splicing machinery in humans is not yet fully elucidated, partly because splicing factors in humans have not been exhaustively identified. Furthermore, experimental methods for splicing factor identification are time-consuming and lab-intensive. Although many computational methods have been proposed for the identification of RNA-binding proteins, there exists no development that focuses on the identification of RNA-splicing related proteins so far. Therefore, we are motivated to design a method that focuses on the identification of human splicing factors using experimentally verified splicing factors. The investigation of amino acid composition reveals that there are remarkable differences between splicing factors and non-splicing proteins. A support vector machine (SVM) is utilized to construct a predictive model, and the five-fold cross-validation evaluation indicates that the SVM model trained with amino acid composition could provide a promising accuracy (80.22%). Another basic feature, amino acid dipeptide composition, is also examined to yield a similar predictive performance to amino acid composition. In addition, this work presents that the incorporation of evolutionary information and domain information could improve the predictive performance. The constructed models have been demonstrated to effectively classify (73.65% accuracy) an independent data set of human splicing factors. The result of independent testing indicates that in silico identification could be a feasible means of conducting preliminary analyses of splicing factors and significantly reducing the number of potential targets that require further in vivo or in vitro confirmation

Large-scale RNAi screens identify novel genes that interact with the C. elegans retinoblastoma pathway as well as splicing-related components with synMuv B activity

BACKGROUND: The retinoblastoma tumor suppressor (Rb) acts in a conserved pathway that is deregulated in most human cancers. Inactivation of the single Rb-related gene in Caenorhabditis elegans, lin-35, has only limited effects on viability and fertility, yet causes changes in cell-fate and cell-cycle regulation when combined with inactivation of specific other genes. For instance, lin-35 Rb is a synthetic multivulva (synMuv) class B gene, which causes a multivulva phenotype when inactivated simultaneously with a class A or C synMuv gene. RESULTS: We used the ORFeome RNAi library to identify genes that interact with C. elegans lin-35 Rb and identified 57 genes that showed synthetic or enhanced RNAi phenotypes in lin-35 mutants as compared to rrf-3 and eri-1 RNAi hypersensitive mutants. Based on characterizations of a deletion allele, the synthetic lin-35 interactor zfp-2 was found to suppress RNAi and to cooperate with lin-35 Rb in somatic gonad development. Interestingly, ten splicing-related genes were found to function similar to lin-35 Rb, as synMuv B genes that prevent inappropriate vulval induction. Partial inactivation of specific spliceosome components revealed further similarities with lin-35 Rb functions in cell-cycle control, transgene expression and restricted expression of germline granules. CONCLUSION: We identified an extensive series of candidate lin-35 Rb interacting genes and validated zfp-2 as a novel lin-35 synthetic lethal gene. In addition, we observed a novel role for a subset of splicing components in lin-35 Rb-controlled processes. Our data support novel hypotheses about possibilities for anti-cancer therapies and multilevel regulation of gene expression

Prospectives

Tiré de: Prospectives, vol. 7, no 2, avril 1971Titre de l'écran-titre (visionné le 24 janv. 2013

Molecular-Genetic Mapping of Zebrafish Mutants with Variable Phenotypic Penetrance

Forward genetic screens in vertebrates are powerful tools to generate models relevant to human diseases, including neuropsychiatric disorders. Variability in phenotypic penetrance and expressivity is common in these disorders and behavioral mutant models, making their molecular-genetic mapping a formidable task. Using a ‘phenotyping by segregation’ strategy, we molecularly map the hypersensitive zebrafish houdini mutant despite its variable phenotypic penetrance, providing a generally applicable strategy to map zebrafish mutants with subtle phenotypes

Insight into transcription factor gene duplication from Caenorhabditis elegans Promoterome-driven expression patterns

BACKGROUND: The C. elegans Promoterome is a powerful resource for revealing the regulatory mechanisms by which transcription is controlled pan-genomically. Transcription factors will form the core of any systems biology model of genome control and therefore the promoter activity of Promoterome inserts for C. elegans transcription factor genes was examined, in vivo, with a reporter gene approach. RESULTS: Transgenic C. elegans strains were generated for 366 transcription factor promoter/gfp reporter gene fusions. GFP distributions were determined, and then summarized with reference to developmental stage and cell type. Reliability of these data was demonstrated by comparison to previously described gene product distributions. A detailed consideration of the results for one C. elegans transcription factor gene family, the Six family, comprising ceh-32, ceh-33, ceh-34 and unc-39 illustrates the value of these analyses. The high proportion of Promoterome reporter fusions that drove GFP expression, compared to previous studies, led to the hypothesis that transcription factor genes might be involved in local gene duplication events less frequently than other genes. Comparison of transcription factor genes of C. elegans and Caenorhabditis briggsae was therefore carried out and revealed very few examples of functional gene duplication since the divergence of these species for most, but not all, transcription factor gene families. CONCLUSION: Examining reporter expression patterns for hundreds of promoters informs, and thereby improves, interpretation of this data type. Genes encoding transcription factors involved in intrinsic developmental control processes appear acutely sensitive to changes in gene dosage through local gene duplication, on an evolutionary time scale