Cytogenetical anchoring of sheep linkage map and syntenic groups using a sheep BAC library

In order to simultaneously integrate linkage and syntenic groups to the ovine chromosomal map, a sheep bacterial artificial chromosome (BAC) library was screened with previously assigned microsatellites using a sheep-hamster hybrid panel and genetic linkage. Thirty-three BACs were obtained, fluorescently labelled and hybridised on sheep-goat hybrid metaphases (2n = 57). This study allowed us, (i), to anchor all linkage groups on sheep chromosomes, (ii), to give information on the probable position of the centromere on the linkage map for the centromeric chromosomes, (iii), to contradict the previous orientation of the ovine × linkage group by the mapping of BMS1008 on OARXq38. Concerning our somatic cell hybrid panel, this study resulted in the assignment of all the previously unassigned groups to ovine chromosomes and a complete characterisation of the hybrid panel. In addition, since hybridisations were performed on a sheep-goat hybrid, new marker/anchoring points were added to the caprine cytogenetic map

Genetic diversity and population genetic structure analysis of Apis mellifera subspecies in Algeria and Europe based on complementary sex determiner (CSD) gene

International audienceIn honeybees, the mechanism of sex determination depends on genetic variation at the complementary sex determiner ( CSD ) locus, which has a large allelic diversity. In this study, we examined the population genetic structure and genetic diversity within the highly variable region ( HVR ) of CSD in five Apis mellifera subspecies, in addition to Buckfast and unknown mixed ancestry bees. We sequenced CSD in 329 drones, 146 from Algeria ( A. m. intermissa and A. m. sahariensis subspecies) and 183 from Europe ( A. m. ligustica , A. m. carnica , A. m. mellifera subspecies, Buckfast samples, and individuals of unknown mixed ancestry). A total of 119 nucleotide haplotypes were detected. These corresponded to 119 protein haplotypes, of which 81 were new. The analysis of these haplotypes showed that HVR diversity levels were comparable with those in other populations of honeybee worldwide. Paradoxically, this high level of diversity at the locus did not allow for a separation of the samples according to their subspecies origin, which suggested either an evolutionary convergence or a conservation of alleles across subspecies, and an absence of genetic drift. Our results can be used to provide more information about the CSD diversity to include in breeding programs of honeybee populations

Cytogenetical anchoring of sheep linkage map and syntenic groups using a sheep BAC library

In order to simultaneously integrate linkage and syntenic groups to the ovine chromosomal map, a sheep bacterial artificial chromosome (BAC) library was screened with previously assigned microsatellites using a sheep-hamster hybrid panel and genetic linkage. Thirty-three BACs were obtained, fluorescently labelled and hybridised on sheep-goat hybrid metaphases ($2{\rm n} = 57$). This study allowed us, (i), to anchor all linkage groups on sheep chromosomes, (ii), to give information on the probable position of the centromere on the linkage map for the centromeric chromosomes, (iii), to contradict the previous orientation of the ovine X linkage group by the mapping of BMS1008 on OARXq38. Concerning our somatic cell hybrid panel, this study resulted in the assignment of all the previously unassigned groups to ovine chromosomes and a complete characterisation of the hybrid panel. In addition, since hybridisations were performed on a sheep-goat hybrid, new marker/anchoring points were added to the caprine cytogenetic map.Ancrage cytogénétique de la carte de liaison et des groupes de synténie par utilisation d'une banque de BAC ovine. Afin d'intégrer, la carte génétique et les groupes de synténies à la carte chromosomique ovine, nous avons criblé, à l'aide de microsatellites, une banque ovine de chromosomes artificiels de bactéries (BAC). Les microsatellites utilisés font partie de la carte de liaison ovine et ont été localisés précédemment dans notre panel d'hybrides somatiques hamster-mouton. Nous avons isolé 33 clones BAC, marqués en fluorescence et hybridés sur métaphase d'un hybride chèvre-mouton ($2{\rm n} = 57$). Les résultats de cette étude ont apporté plusieurs informations. Au niveau de la carte génétique, ces localisations ont permis l'ancrage des groupes de liaison sur les chromosomes ovins et de donner la position la plus probable du centromère sur les groupes de liaison correspondant aux chromosomes métacentriques. De plus, pour le chromosome X, la localisation du microsatellite BMS1008 a permis de corriger l'orientation du groupe de liaison. Au niveau de notre panel d'hybrides somatiques hamster-mouton, ces résultats ont permis d'assigner cytogénétiquement tous les groupes de synténies à un chromosome ovin, aboutissant à une caractérisation approfondie du panel. Enfin, en utilisant des métaphases d'hybride chèvre-mouton pour les hybridations in situ, nous avons pu ajouter de nouveaux marqueurs et points d'ancrages sur la carte chromosomique caprine