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Genomic imprinting represents an original model of epigenetic regulation resulting in a parent-of-origin expression. Despite the critical role of imprinted genes in mammalian growth, metabolism and neuronal function, there is no molecular tool specifically targeting them for a systematic evaluation. Here, we optimized and compared to bisulfite-based standard a novel methyl-seq system to capture 165 candidate regions for genomic imprinting and ultimately detect parent-of-origin methylation, the main hallmark of imprinting.

Body weight and body metrics of newborn piglets reflect their level of development. We studied a Large White population raised in a single experimental herd. Survival and growth performance of 10,101 piglets originating from 689 litters were analysed. In 440 of these litters, 1,320 piglets contrasting for birth weight were recorded for body length and circumference. At piglet level, the estimated direct and maternal heritability values were were h²d=0.02 and h²m=0.13 for birth weight, h²d=0.65 and h²m=0.21 for the ponderal index and h²d=0.23 and h²m=0.01 for the ratio of circumference to body length. The genetic correlation between the ponderal index and litter size and gestation length tended to be negative.

International audience; We performed a genome wide association study for growth and feed efficiency using the GEMMA software on 679 rabbits genotyped with the Affimetrix Axiom Rabbit 200K Genotyping Array. No significant SNP was found for growth traits or feed intake. Two and 89 chromosome-wide significant SNPs were detected for feed conversion ratio and residual feed intake, respectively. The 89 significant SNPs for residual feed intake were all located on chromosome 18, where the putative functional candidate gene GOT1 could be identified.

International audience; Identifying causal mutations responsible of phenotypes in a time and cost-effective manner remains a challenge still for all species. Although the portfolio of next-generation sequencing methodologies offers a broad range of opportunities nowadays, having the right and suitable molecular genetic tools in non-model organisms is often an issue. For the European rabbit (Oryctolagus cuniculus), considered as an animal model for experimental research, the OryCun2.0 reference genome was released in 2009 and the Affymetrix AxiomOrcun SNP Array was made available in 2016. This novel beadchip gives the possibility to develop conveniently genome-wide association studies (GWAS) in rabbits without however freeing itself from the subsequent steps of causal mutation characterization. Whole exome sequencing (WES) appears as a direct and suitable strategy to target and sequence variants all at once. Unfortunately, no exome enrichment tool exist for rabbits. Here, we proposed to capture the rabbit exome using the marketed human panel since human and rabbit genomes are closely related on the phylogenetic tree of species. We performed heterologous hybridization for 48 rabbits from 7 different populations and generated 2 billion sequencing reads for the whole dataset. The quality of the heterologous hybridization allowed the capture of the rabbit exome and enabled a dataset of 40,000 confident variants that specifically target both protein-coding and extended exons. This method also presents a unique opportunity to investigate both (i) the genetic diversity of different rabbits’ breeds and (ii) the mendelian determinism of specific phenotypes in rabbits without resorting to costly customized tools.

International audience; Deciphering the molecular architecture of coat coloration for a better understanding of the biological mechanisms underlying pigmentation still remains a challenge. We took advantage of a rabbit French experimental population in which both a pattern and a gradient of coloration from white to brown segregated within the himalayan phenotype. The whole experimental design was genotyped using the high density Affymetrix® AxiomOrcun™ SNP Array and phenotyped into 6 different groups ordered from the lighter to the darker. Genome-wide association analyses pinpointed an oligogenic determinism, under recessive and additive inheritance, involving genes already known in melanogenesis (ASIP, KIT, MC1R, TYR), and likely processed pseudogenes linked to ribosomal function, RPS20 and RPS14. We also identified (i) gene-gene interactions through ASIP:MC1R affecting light cream/beige phenotypes while KIT:RPS responsible of dark chocolate/brown colors and (ii) a genome-wide epistatic network involving several others coloration genes such as POT1 or HPS5. Finally, we determined the recessive inheritance of the English spotting phenotype likely involving a copy number variation affecting at least the end of the coding sequence of the KIT gene. Our analyses of coloration as a continuous trait allowed us to go beyond much of the established knowledge through the detection of additional genes and gene-gene interactions that may contribute to the molecular architecture of the coloration phenotype.