References of "Grisart, B"
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See detailGenetic and functional confirmation of the causality of the DGAT1 K232A quantitative trait nucleotide in affecting milk yield and composition
Grisart, B.; Farnir, Frédéric ULg; Karim, Latifa ULg et al

in Proceedings of the National Academy of Sciences of the United States of America (2004), 101(8), 2398-2403

We recently used a positional cloning approach to identify a nonconservative lysine to alanine substitution (K232A) in the bovine DGAT1 gene that was proposed to be the causative quantitative trait ... [more ▼]

We recently used a positional cloning approach to identify a nonconservative lysine to alanine substitution (K232A) in the bovine DGAT1 gene that was proposed to be the causative quantitative trait nucleotide underlying a quantitative trait locus (QTL) affecting milk fat composition, previously mapped to the centromeric end of bovine chromosome 14. We herein generate genetic and functional data that confirm the causality of the DGAT1 K232A mutation. We have constructed a high-density single-nucleotide polymorphism map of the 3.8-centimorgan BULGE30-BULGE9 interval containing the QTL and show that the association with milk fat percentage maximizes at the DGAT1 gene. We provide evidence that the K allele has undergone a selective sweep. By using a baculovirus expression system, we have expressed both DGAT1 alleles in Sf9 cells and show that the K allele, causing an increase in milk fat percentage in the live animal, is characterized by a higher V-max in producing triglycerides than the A allele. [less ▲]

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See detailPositional candidate cloning of a QTL in dairy cattle: Identification of a missense mutation in the bovine DGAT1 gene with major effect on milk yield and composition
Grisart, B.; Coppieters, Wouter ULg; Farnir, Frédéric ULg et al

in Genome Research (2002), 12(2), 222-231

We recently mapped a quantitative trait locus (QTL) with a major effect on milk composition-particularly fat content-to the centromeric end of bovine chromosome 14. We subsequently exploited linkage ... [more ▼]

We recently mapped a quantitative trait locus (QTL) with a major effect on milk composition-particularly fat content-to the centromeric end of bovine chromosome 14. We subsequently exploited linkage disequilibrium to refine the map position of this QTL to a 3-cM chromosome interval bounded by microsatellite markers BULGE13 and BULGE09. We herein report the positional candidate cloning of this QTL, involving (I) the construction of a BAC contig spanning the corresponding marker interval, (2) the demonstration that a very strong candidate gene, acylCoA:diacylglycerol acyltransferase (DGATf), maps to that contig, and (3) the identification of a nonconservative K232A substitution in the DGAT1 gene with a major effect on milk fat content and other milk characteristics. [less ▲]

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See detailSimultaneous mining of linkage and linkage disequilibrium to fine map quantitative trait loci in outbred half-sib pedigrees: Revisiting the location of a quantitative trait locus with major effect on milk production on bovine chromosome 14
Farnir, Frédéric ULg; Grisart, B.; Coppieters, Wouter ULg et al

in Genetics (2002), 161(1), 275-287

A maximum-likelihood QTL mapping method that simultaneously exploits linkage and linkage disequilibrium and that is applicable in outbred half-sib pedigrees is described. The method is applied to fine map ... [more ▼]

A maximum-likelihood QTL mapping method that simultaneously exploits linkage and linkage disequilibrium and that is applicable in outbred half-sib pedigrees is described. The method is applied to fine map a QTL with major effect on milk fat content in a 3-cM marker interval on proximal BTA14. This proximal location is confirmed by applying a haplotype-based association method referred to as recombinant ancestral haplotype analysis. The origin of the discrepancy between the QTL position derived in this work and that of a previous analysis is examined and shown to be due to the existence of distinct marker haplotypes associated with QTL alleles having large substitution effects. [less ▲]

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See detailExtensive Genome-Wide Linkage Disequilibrium in Cattle
Farnir, Frédéric ULg; Coppieters, Wouter ULg; Arranz, J. J. et al

in Genome Research (2000), 10(2), 220-7

A genome-wide linkage disequilibrium (LD) map was generated using microsatellite genotypes (284 autosomal microsatellite loci) of 581 gametes sampled from the dutch black-and-white dairy cattle population ... [more ▼]

A genome-wide linkage disequilibrium (LD) map was generated using microsatellite genotypes (284 autosomal microsatellite loci) of 581 gametes sampled from the dutch black-and-white dairy cattle population. LD was measured between all marker pairs, both syntenic and nonsyntenic. Analysis of syntenic pairs revealed surprisingly high levels of LD that, although more pronounced for closely linked marker pairs, extended over several tens of centimorgan. In addition, significant gametic associations were also shown to be very common between nonsyntenic loci. Simulations using the known genealogies of the studied sample indicate that random drift alone is likely to account for most of the observed disequilibrium. No clear evidence was obtained for a direct effect of selection ("Bulmer effect"). The observation of long range disequilibrium between syntenic loci using low-density marker maps indicates that LD mapping has the potential to be very effective in livestock populations. The frequent occurrence of gametic associations between nonsyntenic loci, however, encourages the combined use of linkage and linkage disequilibrium methods to avoid false positive results when mapping genes in livestock. [less ▲]

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See detailFine-Mapping of Quantitative Trait Loci by Identity by Descent in Outbred Populations: Application to Milk Production in Dairy Cattle
Riquet, J.; Coppieters, Wouter ULg; Cambisano, Nadine ULg et al

in Proceedings of the National Academy of Sciences of the United States of America (1999), 96(16), 9252-9257

We previously mapped a quantitative trait locus (QTL) affecting milk production to bovine chromosome 14. To refine the map position of this QTL, we have increased the density of the genetic map of ... [more ▼]

We previously mapped a quantitative trait locus (QTL) affecting milk production to bovine chromosome 14. To refine the map position of this QTL, we have increased the density of the genetic map of BTA14q11-16 by addition of nine microsatellites and three single nucleotide polymorphisms. Fine-mapping of the QTL was accomplished by a two-tiered approach. In the first phase, we identified seven sires heterozygous "Qq" for the QTL by marker-assisted segregation analysis in a Holstein-Friesian pedigree comprising 1,158 individuals. In a second phase, we genotyped the seven selected sires for the newly developed high-density marker map and searched for a shared haplotype flanking an hypothetical, identical-by-descent QTL allele with large substitution effect. The seven chromosomes increasing milk fat percentage were indeed shown to carry a common chromosome segment with an estimated size of 5 cM predicted to contain the studied QTL. The same haplotype was shown to be associated with increased fat percentage in the general population as well, providing additional support in favor of the location of the QTL within the corresponding interval. [less ▲]

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See detailThe great-grand-daughter design: a simple strategy to increase the power of a grand-daughter design for QTL mapping
Coppieters, Wouter ULg; Kvasz, A.; Arranz, J. J. et al

in Genetical Research (1999), 74

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See detailA Qtl with Major Effect on Milk Yield and Composition Maps to Bovine Chromosome 14
Coppieters, Wouter ULg; Riquet, J.; Arranz, J. J. et al

in Mammalian Genome : Official Journal of the International Mammalian Genome Society (1998), 9(7), 540-4

A whole genome scan was undertaken in a granddaughter design comprising 1158 progeny-tested bulls in order to map QTL influencing milk yield and composition. In this paper we report the identification of ... [more ▼]

A whole genome scan was undertaken in a granddaughter design comprising 1158 progeny-tested bulls in order to map QTL influencing milk yield and composition. In this paper we report the identification of a locus on the centromeric end of bovine Chromosome (Chr) 14, with major effect on fat and protein percentage as well as milk yield. The genuine nature of this QTL was verified using the grand2-daughter design, that is, by tracing the segregating QTL alleles from heterozygous grandsires to their maternal grandsons and confirming the predicted QTL allele substitution effect. [less ▲]

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See detailA Qtl Affecting Milk Yield and Composition Maps to Bovine Chromosome 20: A Confirmation
Arranz, J. J.; Coppieters, Wouter ULg; Berzi, P. et al

in Animal Genetics (1998), 29(2), 107-15

As part of a whole genome scan undertaken to detect quantitative trait loci (QTL) affecting milk yield and composition, we have genotyped a granddaughter design comprising 1152 sons for six microsatellite ... [more ▼]

As part of a whole genome scan undertaken to detect quantitative trait loci (QTL) affecting milk yield and composition, we have genotyped a granddaughter design comprising 1152 sons for six microsatellite markers spanning bovine chromosome 20. An analysis performed across families provided strong evidence (experiment-wise P-values < 0.01) for the presence of a QTL affecting primarily protein percentage towards the telomeric end of the chromosome. A founder sire, shown in a previous study to segregate for a similar QTL in the corresponding chromosome region, was characterized by 29 and 57 sons and maternal grandsons, respectively, in the present design. Sorting corresponding sons and grandsons by paternal or grandpaternal allele provided significant evidence for the segregation of a QTL on chromosome 20. Altogether these results confirm the location of a QTL affecting milk production on bovine chromosome 20. [less ▲]

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See detailA Rank-Based Nonparametric Method for Mapping Quantitative Trait Loci in Outbred Half-Sib Pedigrees: Application to Milk Production in a Granddaughter Design
Coppieters, Wouter ULg; Kvasz, A.; Farnir, Frédéric ULg et al

in Genetics (1998), 149(3), 1547-55

We describe the development of a multipoint nonparametric quantitative trait loci mapping method based on the Wilcoxon rank-sum test applicable to outbred half-sib pedigrees. The method has been evaluated ... [more ▼]

We describe the development of a multipoint nonparametric quantitative trait loci mapping method based on the Wilcoxon rank-sum test applicable to outbred half-sib pedigrees. The method has been evaluated on a simulated dataset and its efficiency compared with interval mapping by using regression. It was shown that the rank-based approach is slightly inferior to regression when the residual variance is homoscedastic normal; however, in three out of four other scenarios envisaged, i.e., residual variance heteroscedastic normal, homoscedastic skewed, and homoscedastic positively kurtosed, the latter outperforms the former one. Both methods were applied to a real data set analyzing the effect of bovine chromosome 6 on milk yield and composition by using a 125-cM map comprising 15 microsatellites and a granddaughter design counting 1158 Holstein-Friesian sires. [less ▲]

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See detailGlucose metabolism during bovine preimplantation development: analysis of gene expression in single oocytes and embryos.
Lequarré, Anne-Sophie ULg; Grisart, B.; Schuurbiers, N. et al

in Molecular Reproduction and Development (1997), 48(2), 216-26

Glucose metabolism of the bovine embryo is low during the first cleavages and increases sharply after the major resumption of the genome (8-16 cells). The mRNA level for genes involved in glucose ... [more ▼]

Glucose metabolism of the bovine embryo is low during the first cleavages and increases sharply after the major resumption of the genome (8-16 cells). The mRNA level for genes involved in glucose metabolism was tested by RT-PCR on individual oocytes and embryos at different stages of development. These genes were: glucose transport GLUT-1, hexokinase (HK), glucose-6-phosphatase-dehydrogenase (G6PDH), and glucose-phosphate-isomerase (GPI); actin was used as a reference transcript. RT-PCR results revealed three types of oocytes or embryos: positive with a PCR signal for each transcript considered, nul with no signal for any transcript, and heterogeneous with a PCR signal for some transcripts and none for others. The number of nul and heterogeneous samples was higher for slow than for fast-cleaving embryos (81% vs. 36%), and the proportion of positive embryos increased significantly at the 16-cell and morula stages (P < 0.002), suggesting a correlation between mRNA content and developmental capacity. In positive embryos, GLUT-1 level was reduced by half during maturation and fertilization. Actin and hexokinase mRNA levels decreased during the first cleavages, but significantly increased at the 16-cell and morula stages, respectively. GPI transcript remained stable throughout development, whereas there was a significant rise for G6PDH at the 4-cell stage, perhaps due to a polyadenylation process. Finally, the absence or decrease in intensity of several transcripts at the blastocyst stage suggests suboptimal culture conditions. [less ▲]

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