A Deletion in Exon 9 of the LIPH Gene Is Responsible for the Rex Hair Coat Phenotype in Rabbits (Oryctolagus cuniculus)

The fur of common rabbits is constituted of 3 types of hair differing in length and diameter while that of rex animals is essentially made up of amazingly soft down-hair. Rex short hair coat phenotypes in rabbits were shown to be controlled by three distinct loci. We focused on the “r1” mutation which segregates at a simple autosomal-recessive locus in our rabbit strains. A positional candidate gene approach was used to identify the rex gene and the corresponding mutation. The gene was primo-localized within a 40 cM region on rabbit chromosome 14 by genome scanning families of 187 rabbits in an experimental mating scheme. Then, fine mapping refined the region to 0.5 cM (Z = 78) by genotyping an additional 359 offspring for 94 microsatellites present or newly generated within the first defined interval. Comparative mapping pointed out a candidate gene in this 700 kb region, namely LIPH (Lipase Member H). In humans, several mutations in this major gene cause alopecia, hair loss phenotypes. The rabbit gene structure was established and a deletion of a single nucleotide was found in LIPH exon 9 of rex rabbits (1362delA). This mutation results in a frameshift and introduces a premature stop codon potentially shortening the protein by 19 amino acids. The association between this deletion and the rex phenotype was complete, as determined by its presence in our rabbit families and among a panel of 60 rex and its absence in all 60 non-rex rabbits. This strongly suggests that this deletion, in a homozygous state, is responsible for the rex phenotype in rabbits

A Deletion in Exon 9 of the LIPH Gene Is Responsible for the Rex Hair Coat Phenotype in Rabbits (Oryctolagus cuniculus)

The fur of common rabbits is constituted of 3 types of hair differing in length and diameter while that of rex animals is essentially made up of amazingly soft down-hair. Rex short hair coat phenotypes in rabbits were shown to be controlled by three distinct loci. We focused on the “r1” mutation which segregates at a simple autosomal-recessive locus in our rabbit strains. A positional candidate gene approach was used to identify the rex gene and the corresponding mutation. The gene was primo-localized within a 40 cM region on rabbit chromosome 14 by genome scanning families of 187 rabbits in an experimental mating scheme. Then, fine mapping refined the region to 0.5 cM (Z = 78) by genotyping an additional 359 offspring for 94 microsatellites present or newly generated within the first defined interval. Comparative mapping pointed out a candidate gene in this 700 kb region, namely LIPH (Lipase Member H). In humans, several mutations in this major gene cause alopecia, hair loss phenotypes. The rabbit gene structure was established and a deletion of a single nucleotide was found in LIPH exon 9 of rex rabbits (1362delA). This mutation results in a frameshift and introduces a premature stop codon potentially shortening the protein by 19 amino acids. The association between this deletion and the rex phenotype was complete, as determined by its presence in our rabbit families and among a panel of 60 rex and its absence in all 60 non-rex rabbits. This strongly suggests that this deletion, in a homozygous state, is responsible for the rex phenotype in rabbits

Construction d'une carte intégrée génétique et cytogénétique chez le lapin européen (Oryctolagus cuniculus) (application à la primo- localisation du caractère rex)

Chez le lapin, la majorité des outils de cartographie étaient absents au démarrage du projet. Nous avons donc entrepris de construire une carte intégrée génétique et cytogénétique dans cette espèce et de l'utiliser pour localiser un caractère de fourrure intéressant particulièrement l'INRA, appelé rex. Notre objectif a été de produire simultanément une carte cytogénétique de gènes et de microsatellites pour construire ensuite une carte génétique en typant les microsatellites dans les familles de référence. Pour couvrir l'ensemble du génome de lapin, des gènes pour chaque bande chromosomique humaine ont été sélectionnés puis recherchés dans la banque de BAC. Les BAC identifiés ont ensuite été localisés par FISH sur les chromosomes de lapin et sous-clonés pour identifier des microsatellites. Des localisations pour 248 nouveaux gènes répartis sur tous les chromosomes ont été obtenues, enrichissant d'un facteur 8 la carte cytogénétique du lapin. Parmi les 305 microsatellites obtenus, 178 sont localisés sur tous les chromosomes de lapin sauf OCU21. Huit familles de référence de trois générations qui ségrégent pour le caractère rex, soit un total de 187 animaux, ont été produites. La carte génétique compte à ce jour 118 marqueurs, dont 94 sont répartis en 21 groupes de liaison ancrés sur 18 chromosomes de lapin et 22 sont orphelins mais avec une localisation cytogénétique. Au final, cette carte génétique couvre 2929 cM avec des microsatellites répartis sur tous les chromosomes sauf OCU20 et 21. La carte intégrée a été validée par la localisation de deux marqueurs phénotypiques, angora et albinos et a permis de localiser le caractère rex.Most mapping tools were still not developed at the beginning of the project for the rabbit. Therefore, we have undertaken to construct an integrated genetic and cytogenetic map and to use it to map the rex character, involved in the quality of rabbit fur. Our aim was to produce simultaneously a cytogenetic map containing genes and (TG)n or (TC)n microsatellites and to construct a genetic map by typing the microsatellites in reference families. In order to cover the whole of the rabbit genome with markers, genes for each human chromosomal band were selected and searched in the rabbit BAC library. Isolated BAC clones were localized by FISH on the rabbit chromosomes and then sub-cloned to produce microsatellite sequences. We have localized 248 new genes distributed over all the rabbit chromosomes, enriching 8-fold the rabbit cytogenetic map. Among the 305 microsatellites obtained, 178 were localized on every rabbit chromosome except OCU21. Eight reference rabbit families were produced with three generations and 187 animals in which the rex character segregates. To date, this genetic map contains 118 markers. Among these markers, 94 are distributed in 21 linkage groups anchored to 18 rabbit chromosomes, 22 are localized by FISH with genotyping information. In conclusion, this genetic map covers 2929 cM with microsatellites on all the chromosomes except OCU20 and 21, among which 51 are directly integrated in the cytogenetic map.The integrated map obtained during this work is validated by the localization of two phenotypic markers, angora and albinos. It has also made it possible to localize the rex characterVERSAILLES-BU Sciences et IUT (786462101) / SudocSudocFranceF

Les données récentes sur le génome du lapin

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Functional and RNA-seq analyses provide insights into the protective response mechanisms upon immunization against bovine <em>E. coli</em> mastitis

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Looking for correlates of protection against bovine <em>Escherichia coli</em> mastitis: the local recruitment of Th17 cells upon mammary immunization

International audienc

Genetic determinism of fearfulness, general activity and feeding behavior in chickens and its relationship with digestive efficiency

The genetic relationships between behavior and digestive efficiency were studied in 860 chickens from a cross between two lines divergently selected on digestive efficiency. At 2 weeks of age each chick was video-recorded in the home pen to characterize general activity and feeding behavior. Tonic immobility and open-field tests were also carried out individually to evaluate emotional reactivity (i.e. the propensity to express fear responses). Digestive efficiency was measured at 3 weeks. Genetic parameters of behavior traits were estimated. Birds were genotyped on 3379 SNP markers to detect QTLs. Heritabilities of behavioral traits were low, apart from tonic immobility (0.17–0.18) and maximum meal length (0.14). The genetic correlations indicated that the most efficient birds fed more frequently and were less fearful. We detected 14 QTL (9 for feeding behavior, 3 for tonic immobility, 2 for frequency of lying). Nine of them co-localized with QTL for efficiency, anatomy of the digestive tract, feed intake or microbiota composition. Four genes involved in fear reactions were identified in the QTL for tonic immobility on GGA1

Nation-wide and local diversity of the fish pathogen Flavobacterium psychrophilum in Japan revealed by MLST analysis.

International audienc