Project description:Gene copy number variations (CNVs) involved in phenotypic variations have already been shown in plants, but genome-wide testing of CNVs for adaptive variation was not doable until recent technological developments. Thus, reports of the genomic architecture of adaptation involving CNVs remain scarce to date. Here, we investigated F1 progenies of an intra-provenance cross (north-north cross, 58th parallel) and an inter-provenances cross (north-south cross, 58th/49th parallels) for CNVs using comparative genomic hybridization on arrays of probes targeting gene sequences in balsam poplar (Populus balsamifera L.), a wide-spread North American forest tree. Results: A total of 1,721 genes were found in varying copy numbers over the set of 19,823 tested genes. These gene CNVs presented an estimated average size of 8.3 kb and were distributed over poplar’s 19 chromosomes including 22 hotspot regions. Gene CNVs number was higher for the inter-provenance progeny in accordance with an expected higher genetic diversity related to the composite origin of this family. Regression analyses between gene CNVs and seven adaptive trait variations resulted in 23 significant links; among these adaptive gene CNVs, 30% were located in hotspots. One-to-five gene CNVs were found related to each of the measured adaptive traits and annotated for both biotic and abiotic stress responses. These annotations can be related to the occurrence of a higher pathogenic pressure in the southern parts of balsam poplar’s distribution, and higher photosynthetic assimilation rates and water-use efficiency at high-latitudes. Overall, our findings suggest that gene CNVs typically having higher mutation rates than SNPs, may in fact represent efficient adaptive variations against fast-evolving pathogens.
Project description:It is commonly, although not universally, accepted that most intra- and inter-specific genome sequence variations are more or less neutral, whereas a large fraction of organism-level phenotypic variations are adaptive. Gene expression levels are molecular phenotypes that bridge the gap between genotypes and corresponding organism-level phenotypes. Yet, it is unknown whether natural variations in gene expression levels are mostly neutral or adaptive. Here we address this fundamental question by genome-wide profiling and comparison of gene expression levels in nine yeast strains belonging to three closely related Saccharomyces species and originating from five different ecological environments.
Project description:We have employed a laser capture microdissection technique and single nucleotide polymorphism arrays to characterize genomic alterations associated with the development of glioblastomas. Combined analysis of LOH and copy number revealed that more than half of the identified 254 LOH loci showed no copy number alteration, indicating the presence of copy-number neutral LOH Keywords: DNA copy number, Loss of heterozygosity
Project description:To study the population genetics context of the Saqqaq individual we carried out Illumina Bead-Array-based genotyping on four native North American and twelve north Asian populations.
