AMMA information system: an efficient cross-disciplinary tool and a legacy for forthcoming projects

International audienceIn the framework of the African Monsoon Multidisciplinary Analyses (AMMA) programme, several tools have been developed in order to facilitate and speed up data and information exchange between researchers from different disciplines. The AMMA information system includes a multidisciplinary user-friendly distributed data management and distribution system, a reports and quick looks archive associated with a display website and scientific papers exchange systems. All the applications have been developed by several French institutions and fully duplicated in Niamey, Niger

Novel Insights into the Bovine Polled Phenotype and Horn Ontogenesis in Bovidae

Despite massive research efforts, the molecular etiology of bovine polledness and the developmental pathways involved in horn ontogenesis are still poorly understood. In a recent article, we provided evidence for the existence of at least two different alleles at the Polled locus and identified candidate mutations for each of them. None of these mutations was located in known coding or regulatory regions, thus adding to the complexity of understanding the molecular basis of polledness. We confirm previous results here and exhaustively identify the causative mutation for the Celtic allele (PC) and four candidate mutations for the Friesian allele (PF). We describe a previously unreported eyelash-and-eyelid phenotype associated with regular polledness, and present unique histological and gene expression data on bovine horn bud differentiation in fetuses affected by three different horn defect syndromes, as well as in wild-type controls. We propose the ectopic expression of a lincRNA in PC/p horn buds as a probable cause of horn bud agenesis. In addition, we provide evidence for an involvement of OLIG2, FOXL2 and RXFP2 in horn bud differentiation, and draw a first link between bovine, ovine and caprine Polled loci. Our results represent a first and important step in understanding the genetic pathways and key process involved in horn bud differentiation in Bovidae

Eclairages apportés par l'identification moléculaire des gènes de coloration chez le poulet sur le mode d'action des mutations, l'homologie de locus entre espèces et la domestication

National audienc

Complete association between a retroviral insertion in the tyrosinase gene and the recessive white mutation in chickens

<p>Abstract</p> <p>Background</p> <p>In chickens, three mutant alleles have been reported at the <it>C </it>locus, including the albino mutation, and the recessive white mutation, which is characterized by white plumage and pigmented eyes. The albino mutation was found to be a 6 bp deletion in the tyrosinase (<it>TYR</it>) gene. The present work describes an approach to identify the structural rearrangement in the <it>TYR </it>gene associated with the recessive white mutation.</p> <p>Results</p> <p>Molecular analysis of the chicken <it>TYR </it>gene has revealed a major structural difference (Restriction Fragment Length Polymorphism, RFLP) in the genomic DNA of the recessive white chicken. A major size difference of 7.7 kb was found in intron 4 of the <it>TYR </it>gene by long-range PCR. Molecular cloning and sequencing results showed the insertion of a complete avian retroviral sequence of the Avian Leukosis Virus (<it>ALV</it>) family. Several aberrant transcripts of the tyrosinase gene were found in 10 week old recessive white chickens but not in the homozygous wild type colored chicken. We established a rapid genotyping diagnostic test based on the discovery of this retroviral insertion. It shows that all homozygous carriers of this insertion had a white plumage in various chicken strains. Furthermore, it was possible to distinguish heterozygous carriers from homozygous normal chickens in a segregating line.</p> <p>Conclusion</p> <p>In this study, we conclude that the insertion of a complete avian retroviral sequence in intron 4 of the tyrosinase gene is diagnostic of the recessive white mutation in chickens. This insertion causes aberrant transcripts lacking exon 5, and we propose that this insertion is the causal mutation for the recessive white allele in the chicken.</p

La lignée " Leghorn double jaune" : un modèle d'étude du déterminisme génétique du taux d'ovulation chez la poule

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A retrovirus insertion causes abnormal expression of the tyrosinase gene in recessive white chickens

Chantier qualité spécifique "Auteurs Externes" département de Génétique animale : uniquement liaison auteur au référentiel HR-Accessabsen

Effet du nanisme lié au sexe (Dwarf) sur l'expression des gènes du foie chez la poule

The sex-linked dwarfism (SLD), corresponding to the genomic locus « dwarf « (dw) is due to mutations in theGrowth Hormone Receptor (GHR) gene on chromosome Z. In the experimental Leghorn population used in thisstudy the dwarf condition is due to a mutation causing a loss of function of the GHR gene. This mutation ischaracterized by a significant reduction of body size in hemizygous females (30%) and homozygous males(40%). In addition to its commercial use in the broiler dam lines to improve production efficiency, the SLDmutation is also an interesting model to unravel regulatory pathways depending on GH and to investigatecomplex traits such as energy expenditure and heat resistance. In this study, we analyzed the liver transcriptomefrom 24 SLD and 24 wild type birds of 12 weeks of age obtained by crossing a heterozygous “dw” Leghorn cockwith 12 females of an inbred Leghorn line to obtain wild type and dwarf sib and half-sib hens. Differentialexpression analysis revealed that the sex-linked Dwarf mutation produces dramatic changes in liver geneexpression. In total more than 5000 differentially expressed (DE) genes were identified (adjusted p-value <0.05),2219 of which had a log fold-change ≤ |0.2|. Functional analyses of sex-linked Dwarf-induced DE genes indicatean alteration of lipid and amino acid metabolism, molecular transport and cellular growth and proliferation.Le nanisme lié au sexe (SLD), correspondant au locus "dwarf" (dw), est la conséquence de mutations dans legène du récepteur de l’hormone de croissance (GHR), localisé sur le chromosome Z. Dans la populationexpérimentale White Leghorn utilisée dans cette étude, le nanisme est dû à une « perte de fonction » du gèneGHR. Elle entraîne une réduction significative de la taille du corps chez les femelles hémizygotes (30%) et lesmâles homozygotes (40%). Les poules naines sont utilisées commercialement dans les lignées maternelles depoulet de chair du fait de leur moindre coût d'élevage. Elles sont aussi un modèle intéressant pour lacompréhension des mécanismes de contrôle de l’expression des gènes par l’hormone de croissance ainsi quel'étude de caractères complexes comme les dépenses d'énergie ou la résistance à la chaleur. Dans cette étude,nous avons étudié le transcriptome du foie sur 24 poules SDL et 24 soeurs et demi-soeurs normales obtenues parcroisement d'un coq hétérozygote "Dw+/dw" avec 12 femelles Leghorn normales. Les résultats montrent que lamutation du nanisme « dw » induit des changements importants dans l'expression d’un grand nombre de gènesdans le foie. Ainsi, plus de 5000 gènes différentiellement exprimés (DE) ont été identifiés (p-value ajustée<0.05), dont 2219 avec un « log fold change » ≤ |0.2|. Des analyses fonctionnelles à partir des gènes DE dans lefoie ont mis en évidence des altérations significatives du métabolisme lipidique et protéique, du transportmoléculaire, de la croissance et la prolifération cellulaire

Adaptation des animaux d'élevage aux multiples contraintes des régions chaudes

En zones difficiles, la pérennité des systèmes d’élevage repose sur la capacité des animaux à survivre, se reproduire et maintenir un niveau de production en situation de fortes contraintes. Les principales contraintes auxquelles les animaux doivent faire face en régions chaudes, sont le climat (température et humidité), la sous-nutrition et les pathologies. Chez les monogastriques comme chez les ruminants, les caractéristiques anatomiques et le comportement alimentaire constituent les principaux facteurs de régulation des échanges thermiques. L’élément clé de l’adaptation comportementale des ruminants à la sous-alimentation est leur capacité à choisir leur alimentation. L’adaptation physiologique porte sur la réduction du métabolisme basal, l’efficience digestive, la valorisation de fourrages grossiers, la mobilisation des réserves corporelles, le recyclage des nutriments et la valorisation efficiente de l’eau. Les travaux les plus significatifs sur la résistance génétique aux maladies portent sur la trypanotolérance, la résistance aux maladies transmises par les tiques et les strongyloses gastro-intestinales. Dans l’élevage moderne, la gestion de ces contraintes environnementales doit se concevoir de façon intégrée. Différentes techniques d’alimentation, de prophylaxie, de gestion d’ambiance des bâtiments d’élevage doivent être combinées pour garantir durablement la pérennité des systèmes d’élevage. Cependant, l’efficacité de cette approche intégrée repose également sur le potentiel adaptatif des animaux pour répondre aux pratiques mises en œuvre. Le développement des productions animales en régions chaudes ne pourra être garanti sans l’utilisation de l’adaptation naturelle des populations animales ou pour le moins, sans inclure les caractères d’adaptation dans les objectifs de sélection des races locales ou spécialisées.The question of adaptation of animals to the tropical environment has become a major challenge for the livestock sector and the scientific community. In harsh areas, the sustainability of farming systems is based on the ability of animals to survive, reproduce and maintain productivity under climatic, food or health constraints. In monogastrics and ruminants, the anatomical characteristics and feeding behavior are key factors regulating heat exchanges (small-size, decrease in subcutaneous fat mass, reduction in feed intake and physical activity). Level of basal metabolic rate, digestive efficiency, ability to utilize lower quality feeds, body reserves mobilization, nutrient recycling and water use efficiency are the main physiological traits of adaptation to underfeeding in ruminants. The most significant works on disease genetic resistance relate to trypanotolerance in African livestock, resistance to ticks or tick-borne diseases like heartwater and resistance to gastrointestinal strongyles. In modern farming systems, management of these environmental constraints must be considered in an integrated framework. Various feeding, environment and health management practices must be combined to reduce risk and maximize productivity. However, sustainable development of livestock production in tropical areas cannot be guaranteed without using the adaptation traits of native animal populations or at least without including adaptation traits in selection program for local and exotic breeds