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Francis Galibert

Publications and source records attributed to Francis Galibert.

At least 19 recordsLinked to original sources
PubMed2006

AutoGRAPH: an interactive web server for automating and visualizing comparative genome maps.

UNLABELLED: AutoGRAPH is an interactive web server for automatic multi-species comparative genomics analyses based on personal datasets or pre-inserted public datasets. This program automatically identifies conserved segments (CS) and breakpoint regions, assesses the conservation of marker/gene order between organisms, constructs synteny maps for two to three species and generates high-quality, interactive displays facilitating the identification of chromosomal rearrangements. AutoGRAPH can also be used for the integration and comparison of several types of genomic resources (meiotic maps, radiation hybrid maps and genome sequences) for a single species, making AutoGRAPH a versatile tool for comparative genomics analysis. AVAILABILITY: http://genoweb.univ-rennes1.fr/tom_dog/AutoGRAPH/. SUPPLEMENTARY INFORMATION: A description of the algorithm and additional information are available at http://genoweb.univ-rennes1.fr/tom_dog/AutoGRAPH/Tutorial.php.

Algorithms↗
PubMed2006

Radiation hybrid mapping of cataract genes in the dog.

PURPOSE: To facilitate the molecular characterization of naturally occurring cataracts in dogs by providing the radiation hybrid location of 21 cataract-associated genes along with their closely associated polymorphic markers. These can be used for segregation testing of the candidate genes in canine cataract pedigrees. METHODS: Twenty-one genes with known mutations causing hereditary cataracts in man and/or mouse were selected and mapped to canine chromosomes using a canine:hamster radiation hybrid RH5000 panel. Each cataract gene ortholog was mapped in relation to over 3,000 markers including microsatellites, ESTs, genes, and BAC clones. The resulting independently determined RH-map locations were compared with the corresponding gene locations from the draft sequence of the canine genome. RESULTS: Twenty-one cataract orthologs were mapped to canine chromosomes. The genetic locations and nearest polymorphic markers were determined for 20 of these orthologs. In addition, the resulting cataract gene locations, as determined experimentally by this study, were compared with those determined by the canine genome project. All genes mapped within or near chromosomal locations with previously established homology to the corresponding human gene locations based on canine:human chromosomal synteny. CONCLUSIONS: The location of selected cataract gene orthologs in the dog, along with their nearest polymorphic markers, serves as a resource for association and linkage testing in canine pedigrees segregating inherited cataracts. The recent development of canine genomic resources make canine models a practical and valuable resource for the study of human hereditary cataracts. Canine models can serve as large animal models intermediate between mouse and man for both gene discovery and the development of novel cataract therapies.

Animals↗
PubMed2006

Eukaryotic control on bacterial cell cycle and differentiation in the Rhizobium-legume symbiosis.

Symbiosis between legumes and Rhizobium bacteria leads to the formation of root nodules where bacteria in the infected plant cells are converted into nitrogen-fixing bacteroids. Nodules with a persistent meristem are indeterminate, whereas nodules without meristem are determinate. The symbiotic plant cells in both nodule types are polyploid because of several cycles of endoreduplication (genome replication without mitosis and cytokinesis) and grow consequently to extreme sizes. Here we demonstrate that differentiation of bacteroids in indeterminate nodules of Medicago and related legumes from the galegoid clade shows remarkable similarity to host cell differentiation. During bacteroid maturation, repeated DNA replication without cytokinesis results in extensive amplification of the entire bacterial genome and elongation of bacteria. This finding reveals a positive correlation in prokaryotes between DNA content and cell size, similar to that in eukaryotes. These polyploid bacteroids are metabolically functional but display increased membrane permeability and are nonviable, because they lose their ability to resume growth. In contrast, bacteroids in determinate nodules of the nongalegoid legumes lotus and bean are comparable to free-living bacteria in their genomic DNA content, cell size, and viability. Using recombinant Rhizobium strains nodulating both legume types, we show that bacteroid differentiation is controlled by the host plant. Plant factors present in nodules of galegoid legumes but absent from nodules of nongalegoid legumes block bacterial cell division and trigger endoreduplication cycles, thereby forcing the endosymbionts toward a terminally differentiated state. Hence, Medicago and related legumes have evolved a mechanism to dominate the symbiosis.

Cell Cycle↗
PubMed2006

Coat colour in dogs: identification of the merle locus in the Australian shepherd breed.

BACKGROUND: Coat colours in canines have many natural phenotypic variants. Some of the genes and alleles involved also cause genetic developmental defects, which are also observed in humans and mice. We studied the genetic bases of the merle phenotype in dogs to shed light on the pigmentation mechanisms and to identify genes involved in these complex pathways. The merle phenotype includes a lack of eumelanic pigmentation and developmental defects, hearing impairments and microphthalmia. It is similar to that observed in microphthalmia mouse mutants. RESULTS: Taking advantage of the dog as a powerful genetic model and using recently available genomic resources, we investigated the segregation of the merle phenotype in a five-generation pedigree, comprising 96 sampled Australian shepherd dogs. Genetic linkage analysis allowed us to identify a locus for the merle phenotype, spanning 5.5 megabases, at the centromeric tip of canine chromosome 10 (CFA10). This locus was supported by a Lod score of 15.65 at a recombination fraction theta = 0. Linkage analysis in three other breeds revealed that the same region is linked to the merle phenotype. This region, which is orthologous to human chromosome 12 (HSA12 q13-q14), belongs to a conserved ordered segment in the human and mouse genome and comprises several genes potentially involved in pigmentation and development. CONCLUSION: This study has identified the locus for the merle coat colour in dogs to be at the centromeric end of CFA10. Genetic studies on other breeds segregating the merle phenotype should allow the locus to be defined more accurately with the aim of identifying the gene. This work shows the power of the canine system to search for the genetic bases of mammalian pigmentation and developmental pathways.

Journal Article↗
PubMed2006

The first radiation hybrid map of a perch-like fish: the gilthead seabream (Sparus aurata L).

Among Teleosts, Perciformes are the largest order of fishes and include numerous species of commercial importance. Perciformes also comprise species of primary interest for evolutionary studies and analysis of the sex determination systems and sex chromosome plasticity. Unfortunately, genomics tools and resources for Perciformes remain to be developed. Here, we report the production of a seabream whole-genome radiation hybrid (RH) panel in which quality was ascertained by the construction of a 2-Mb-resolution RH map. The map encompasses 440 markers (288 microsatellites, 82 gene-based markers, and 70 STS) suitable for linkage analysis and comparative mapping studies. Achievement of a RH panel and a whole-genome RH map should contribute to establishing seabream as a fish model among the Perciformes and should be of importance in aquaculture for marker-assisted selection, improvement of growth performance, and disease management. Development of RH maps in a cost-effective manner for other fishes with the described methodology will offer a powerful approach in aquaculture and will provide extended capabilities for comparing vertebrate genome evolution.

Animals↗
PubMed2005

Genome sequence, comparative analysis and haplotype structure of the domestic dog.

Here we report a high-quality draft genome sequence of the domestic dog (Canis familiaris), together with a dense map of single nucleotide polymorphisms (SNPs) across breeds. The dog is of particular interest because it provides important evolutionary information and because existing breeds show great phenotypic diversity for morphological, physiological and behavioural traits. We use sequence comparison with the primate and rodent lineages to shed light on the structure and evolution of genomes and genes. Notably, the majority of the most highly conserved non-coding sequences in mammalian genomes are clustered near a small subset of genes with important roles in development. Analysis of SNPs reveals long-range haplotypes across the entire dog genome, and defines the nature of genetic diversity within and across breeds. The current SNP map now makes it possible for genome-wide association studies to identify genes responsible for diseases and traits, with important consequences for human and companion animal health.

Animals↗
PubMed2005

Olfactory receptor sequence polymorphism within and between breeds of dogs.

Olfactory receptors, to which odorant molecules specifically bind, are encoded by the largest gene family yet identified in the mammalian genome. We investigated additional polymorphism due to the possible existence of multiple alleles dispersed in different dog breeds by carrying out a survey of the sequences of 16 olfactory receptor genes in a sample of 95 dogs of 20 different breeds. The level of polymorphism was high--all genes were found to have allelic variants--leading to amino acid changes and pseudogenization of some alleles in a number of cases. This preliminary study also revealed that some alleles are breed specific (or rare in the dog population), with some representing the major allele in the breeds concerned.

Amino Acid Substitution↗
PubMed2005

The dog and rat olfactory receptor repertoires.

BACKGROUND: Dogs and rats have a highly developed capability to detect and identify odorant molecules, even at minute concentrations. Previous analyses have shown that the olfactory receptors (ORs) that specifically bind odorant molecules are encoded by the largest gene family sequenced in mammals so far. RESULTS: We identified five amino acid patterns characteristic of ORs in the recently sequenced boxer dog and brown Norway rat genomes. Using these patterns, we retrieved 1,094 dog genes and 1,493 rat genes from these shotgun sequences. The retrieved sequences constitute the olfactory receptor repertoires of these two animals. Subsets of 20.3% (for the dog) and 19.5% (for the rat) of these genes were annotated as pseudogenes as they had one or several mutations interrupting their open reading frames. We performed phylogenetic studies and organized these two repertoires into classes, families and subfamilies. CONCLUSION: We have established a complete or almost complete list of OR genes in the dog and the rat and have compared the sequences of these genes within and between the two species. Our results provide insight into the evolutionary development of these genes and the local amplifications that have led to the specific amplification of many subfamilies. We have also compared the human and rat ORs with the human and mouse OR repertoires.

Animals↗
PubMed2005

Dynamics of mammalian chromosome evolution inferred from multispecies comparative maps.

The genome organizations of eight phylogenetically distinct species from five mammalian orders were compared in order to address fundamental questions relating to mammalian chromosomal evolution. Rates of chromosome evolution within mammalian orders were found to increase since the Cretaceous-Tertiary boundary. Nearly 20% of chromosome breakpoint regions were reused during mammalian evolution; these reuse sites are also enriched for centromeres. Analysis of gene content in and around evolutionary breakpoint regions revealed increased gene density relative to the genome-wide average. We found that segmental duplications populate the majority of primate-specific breakpoints and often flank inverted chromosome segments, implicating their role in chromosomal rearrangement.

Animals↗
PubMed2005

Facilitating genome navigation: survey sequencing and dense radiation-hybrid gene mapping.

Accurate and comprehensive sequence coverage for large genomes has been restricted to only a few species of specific interest. Lower sequence coverage (survey sequencing) of related species can yield a wealth of information about gene content and putative regulatory elements. But survey sequences lack long-range continuity and provide only a fragmented view of a genome. Here we show the usefulness of combining survey sequencing with dense radiation-hybrid (RH) maps for extracting maximum comparative genome information from model organisms. Based on results from the canine system, we propose that from now on all low-pass sequencing projects should be accompanied by a dense, gene-based RH map-construction effort to extract maximum information from the genome with a marginal extra cost.

Animals↗
PubMed2005

Construction of a 2-Mb resolution BAC microarray for CGH analysis of canine tumors.

Recognition of the domestic dog as a model for the comparative study of human genetic traits has led to major advances in canine genomics. The pathophysiological similarities shared between many human and dog diseases extend to a range of cancers. Human tumors frequently display recurrent chromosome aberrations, many of which are hallmarks of particular tumor subtypes. Using a range of molecular cytogenetic techniques we have generated evidence indicating that this is also true of canine tumors. Detailed knowledge of these genomic abnormalities has the potential to aid diagnosis, prognosis, and the selection of appropriate therapy in both species. We recently improved the efficiency and resolution of canine cancer cytogenetics studies by developing a small-scale genomic microarray comprising a panel of canine BAC clones representing subgenomic regions of particular interest. We have now extended these studies to generate a comprehensive canine comparative genomic hybridization (CGH) array that comprises 1158 canine BAC clones ordered throughout the genome with an average interval of 2 Mb. Most of the clones (84.3%) have been assigned to a precise cytogenetic location by fluorescence in situ hybridization (FISH), and 98.5% are also directly anchored within the current canine genome assembly, permitting direct translation from cytogenetic aberration to DNA sequence. We are now using this resource routinely for high-throughput array CGH and single-locus probe analysis of a range of canine cancers. Here we provide examples of the varied applications of this resource to tumor cytogenetics, in combination with other molecular cytogenetic techniques.

Animals↗
PubMed2004

An integrated 4249 marker FISH/RH map of the canine genome.

BACKGROUND: The 156 breeds of dog recognized by the American Kennel Club offer a unique opportunity to map genes important in genetic variation. Each breed features a defining constellation of morphological and behavioral traits, often generated by deliberate crossing of closely related individuals, leading to a high rate of genetic disease in many breeds. Understanding the genetic basis of both phenotypic variation and disease susceptibility in the dog provides new ways in which to dissect the genetics of human health and biology. RESULTS: To facilitate both genetic mapping and cloning efforts, we have constructed an integrated canine genome map that is both dense and accurate. The resulting resource encompasses 4249 markers, and was constructed using the RHDF5000-2 whole genome radiation hybrid panel. The radiation hybrid (RH) map features a density of one marker every 900 Kb and contains 1760 bacterial artificial chromosome clones (BACs) localized to 1423 unique positions, 851 of which have also been mapped by fluorescence in situ hybridization (FISH). The two data sets show excellent concordance. Excluding the Y chromosome, the map features an RH/FISH mapped BAC every 3.5 Mb and an RH mapped BAC-end, on average, every 2 Mb. For 2233 markers, the orthologous human genes have been established, allowing the identification of 79 conserved segments (CS) between the dog and human genomes, dramatically extending the length of most previously described CS. CONCLUSIONS: These results provide a necessary resource for the canine genome mapping community to undertake positional cloning experiments and provide new insights into the comparative canine-human genome maps.

Animals↗
PubMed2004

CRH_Server: an online comparative and radiation hybrid mapping server for the canine genome.

UNLABELLED: CRH_Server is an on line Comparative and Radiation Hybrid mapping Server dedicated to canine genomics. CRH_Server allows users to compute their own RH data using the current canine RH map, and allows comparative dog/human mapping analyses. Finally, it suggests multiple options for storage and queries of the dog RH database. AVAILABILITY: http://idefix.univ-rennes1.fr:8080/Dogs/rh-server.html. SUPPLEMENTARY INFORMATION: All information is available at http://idefix.univ-rennes1.fr:8080/Dogs/help_rh-server.html.

Algorithms↗
PubMed2004

A high-resolution comparative map of canine Chromosome 5q14.3-q33 constructed utilizing the 1.5x canine genome sequence.

A high-density map of the region of canine Chromosome 5 (CFA5) surrounding the evolutionary breakpoint between human Chromosomes 1p32 and 17pll was constructed by integrating a radiation hybrid map including 41 microsatellites, 10 BACs, and 59 genes and a linkage map including 18 markers. A collection of canine genomic survey sequences providing 1.5x coverage was used to identify dog orthologs of human genes, proving instrumental in the development of this map. Of particular interest is the canine BHD gene, within which we have previously described a single nucleotide polymorphism associated with Hereditary Multifocal Renal Cystadenocarcinoma and Nodular Dermatofibrosis (RCND) in German Shepherd dogs. The corresponding region of the human genome is particularly gene rich, containing genes involved in development, metabolism, and cancer that are likely to be of interest in future mapping studies. This current mapping effort on CFA5 expands the degree to which initial findings of linkage in canine families can be followed by successful positional cloning efforts and increases the value of the human genome sequence for defining candidate genes. Moreover, this study demonstrates the utility of genomic survey sequences when combined with accurate genome maps for rapid mapping of disease susceptibility loci.

Animals↗
PubMed2004

Chromosome-specific microsatellite multiplex sets for linkage studies in the domestic dog.

To expedite linkage studies and positional cloning efforts in the dog, Minimal Screening Set 2 (MSS-2) of 327 canine microsatellite markers has been multiplexed into chromosome-specific panels. MSS-2 provides 9 Mb coverage of the canine genome with no gaps larger than 17.1 Mb and is the most recent and comprehensive set of microsatellites available for whole-genome scans. Markers were labeled with fluorescent dyes based on locations and expected product sizes to facilitate the multiplexing of a maximum number of markers for each chromosome. All markers are amplified using a single thermal cycling program and PCR mix and are optimized for resolution on an ABI 3100 genetic analyzer. Sixty-nine chromosome-specific panels were created by coamplification of a maximum number of markers and subsequent coloading of the remaining markers.

Animals↗
PubMed2004

Smc01944, a secreted peroxidase induced by oxidative stresses in Sinorhizobium meliloti 1021.

Sequencing of the Sinorhizobium meliloti strain 1021 genome led to the detection of 6204 open reading frames, 41 % of which have no hypothetical function. To help annotate this genome, a transcriptome analysis was carried out with a dedicated microarray consisting of 146 genes belonging to three different classes: (i) no hypothetical function; (ii) potentially involved in oxidative stress responses; (iii) known to participate in oxidative stress responses (e.g. catalase and superoxide dismutase genes). This transcriptome analysis, together with biological experiments and in silico investigations, identified new genes induced by exogenous H(2)O(2). The smc01944 gene was the most strongly induced: quantitative PCR showed that the amount of smc01944 mRNA increased 50-fold following the addition of 10 mM H(2)O(2), whereas the amount of katA mRNA (encoding a catalase) only increased 10-fold. Smc01944 is a non-haem chloroperoxidase (Cpo). The only member of this family to have been so far characterized is encoded by prxC of Pseudomonas fluorescens. Unexpectedly, the NH(2)-terminus of Smc01944 includes a signal peptide and Smc01944 is secreted into the supernatant. Interestingly, smc01944 is preceded by smc01945, encoding an OhrR-like regulator (MarR family). Thus, Smc01944 is the first exported Cpo encoded by a gene possibly regulated by an OhrR regulator. It was also shown that smc01944 is induced by t-butyl and cumene hydroperoxides but only slightly by menadione. The study of Smc01944 described in this work showed that the oxidative stress response of S. meliloti seems to differ from that of other bacteria characterized to date.

Amino Acid Sequence↗
PubMed2003

Comparison of the canine and human olfactory receptor gene repertoires.

BACKGROUND: Olfactory receptors (ORs), the first dedicated molecules with which odorants physically interact to arouse an olfactory sensation, constitute the largest gene family in vertebrates, including around 900 genes in human and 1,500 in the mouse. Whereas dogs, like many other mammals, have a much keener olfactory potential than humans, only 21 canine OR genes have been described to date. RESULTS: In this study, 817 novel canine OR sequences were identified, and 640 have been characterized. Of the 661 characterized OR sequences, representing half of the canine repertoire, 18% are predicted to be pseudogenes, compared with 63% in human and 20% in mouse. Phylogenetic analysis of 403 canine OR sequences identified 51 families, and radiation-hybrid mapping of 562 showed that they are distributed on 24 dog chromosomes, in 37 distinct regions. Most of these regions constitute clusters of 2 to 124 closely linked genes. The two largest clusters (124 and 109 OR genes) are located on canine chromosomes 18 and 21. They are orthologous to human clusters located on human chromosomes 11q11-q13 and HSA11p15, containing 174 and 115 ORs respectively. CONCLUSIONS: This study shows a strongly conserved genomic distribution of OR genes between dog and human, suggesting that OR genes evolved from a common mammalian ancestral repertoire by successive duplications. In addition, the dog repertoire appears to have expanded relative to that of humans, leading to the emergence of specific canine OR genes.

Animals↗