Contribution a l'etude du determinisme genetique de la susceptibilite aux elements transposables P dans les populations naturelles de Drosophila melanogaster

SIGLECNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Drosophilas as "fruit flies"

International audienc

Genetic heterogeneity of Berber peoples as a result of differential migration and admixture patterns

Trabajo presentado en la Annual Meeting of the Society for Molecular Biology and Evolution (SMBE 2015), celebrada en Viena del 12 al 16 de julio de 2015.The genome-wide structure of North African populations has been describe d as an amalgam of autochthonous, Middle Eastern, European and Sub-Saharan ancestries. The indigenous North African genetic ancestry has been estimated to be derived from a "back to Africa" migration dated in pre-Holocean times, and suggested to be in high est frequency in Berber populations, which are considered the autochthonous populations of North Africa.The lack of genetic knowledge on Berber populations in the current datasets prevents the understanding of the complex population processes occurred in North Africa. We have genotyped ~900,000 genome-wide SNPs in four different Berber groups and compared the results with other North African and neighboring groups. Our research reflects the complex structure of North African populations due to multiple admixture processes. Berber groups are very heterogeneous, showing different patterns of admixture and demographic histories, such as relevant endogamy levels within groups. The analysis of haplotype structure and the ancestral relationship between individuals has allowed us to estimate historical dates for some migrations coming from the Middle East and Sub-Saharan Africa into North Africa, affecting in an heterogeneous way the populations of the region. In addition, the comparison of autosomal and sexual chromosomes has shown a sexual bias in the admixture between North African populations and their surrounding neighbors, being the North African autochthonous component mainly derived from males and the European admixture driven by women. This study brings light to the origin of Berbers and the complex admixture processes in the population of North Africa.N

HLA class II DNA polymorphism in a Moroccan population from the Souss, Agadir area

HLA DRB1, DQA1 and DQB1 polymorphisms were analyzed by PCR-SSO typing in a sample of the Moroccan population from Souss. Uneven allelic frequency distributions are observed at each locus, with particularly high frequencies for DRB1*0701, DRB1*0301, DQA1*0501, DQA1*0201, and DQB1*0201. Only three haplotypes (DRB1*0701-DQA1*0201-DQB1*0201, DRB1*0301-DQA1*0501-DQB1*0201 and DRB1*11-DQA1*0501-DQB1*0301) account for nearly 50% of the total gene frequencies. A genetic distance analysis reveals that the Moroccan population is close to the Spanish and the Algerians, who live in geographically neighboring areas. However, the Souss population is also characterized by a lower level of genetic diversity compared to other African and European populations from the Mediterranean area. This may be the result of a rapid genetic drift due to their likely geographical and/or cultural isolation

Completing the genetic landscape of Nort Africa: Genomic chatracterization of berber peoples

Trabajo presentado en la 4th Meeting of the Spanish Society of the Evolutionary Biology (SESBE 2013) celebrada en Barcelona del 27 al 29 de noviembre de 2013.N

Recent historical migrations have shaped the gene pool of arabs and berbers in North Africa

North Africa is characterized by its diverse cultural and linguistic groups and its genetic heterogeneity. Genomic data has shown an amalgam of components mixed since pre-Holocean times. Though no differences have been found in uniparental and classical markers between Berbers and Arabs, the two main ethnic groups in the region, the scanty genomic data available have highlighted the singularity of Berbers. We characterize the genetic heterogeneity of North African groups, focusing on the putative differences of Berbers and Arabs, and estimate migration dates. We analyze genome-wide autosomal data in five Berber and six Arab groups, and compare them to Middle Easterns, sub-Saharans, and Europeans. Haplotype-based methods show a lack of correlation between geographical and genetic populations, and a high degree of genetic heterogeneity, without strong differences between Berbers and Arabs. Berbers enclose genetically diverse groups, from isolated endogamous groups with high autochthonous component frequencies, large homozygosity runs and low effective population sizes, to admixed groups with high frequencies of sub-Saharan and Middle Eastern components. Admixture time estimates show a complex pattern of recent historical migrations, with a peak around the 7th century C.E. coincident with the Arabization of the region; sub-Saharan migrations since the 1st century B.C. in agreement with Roman slave trade; and a strong migration in the 17th century C.E., coincident with a huge impact of the trans-Atlantic and trans-Saharan trade of sub-Saharan slaves in the Modern Era. The genetic complexity found should be taken into account when selecting reference groups in population genetics and biomedical studies.This work was supported by the Spanish MINECO grants CGL2013-44351-P and the “María de Maeztu” Program for Units of Excellence in R&D (MDM-2014-0370); and the Generalitat de Catalunya grant 2014SGR866