Weikard, Rosemarie, Christa Kü hn, Tom Goldammer, Gertraude Freyer, and Manfred Schwerin. The bovine PPARGC1A gene: molecular characterization and association of an SNP with variation of milk fat synthesis. Physiol Genomics 21: 1-13, 2005; doi:10.1152/physiolgenomics.00103.2004.-Several studies in a variety of breeds have reported at least two QTL for milk production traits, including milk fat synthesis on bovine chromosome 6 (BTA6), comprising a region that comparatively has been mapped to equivalent syntenic chromosome intervals in human, pig, and mouse harboring loci associated with type II diabetes and obesity-related traits. We identified the bovine peroxysome proliferator-activated receptor-␥ coactivator-1␣ gene (PPARGC1A) as a plausible positional and functional candidate gene for a previously described QTL for milk fat yield on BTA6 because of its chromosomal position and its key role in energy, fat, and glucose metabolism. To analyze the role of the bovine PPARGC1A gene in regulation of milk fat synthesis in dairy cattle, we determined its cDNA sequence, genomic organization, chromosomal localization, and expression pattern. The bovine PPARGC1A gene is organized in 13 exons comprising 6,261 bp and is expressed at different levels in a large number of tissues. Bovine PPARGC1A cDNA and protein sequences showed substantial similarity (92-95%) to its respective orthologs from human, rat, and mouse. Screening for polymorphisms in the coding sequence, exon/ intron boundaries, 5Ј-and 3Ј-untranslated regions, and promoter region of the PPARGC1A gene in sires with a different genotype at the QTL for milk fat yield as well as in a multibreed panel revealed a total of 11 polymorphic loci. A significant association between an SNP in intron 9 of the PPARGC1A gene and milk fat yield was observed in a major dairy cattle population, indicating that the PPARGC1A gene could be involved in genetic variation underlying the QTL for milk fat synthesis on BTA6.quantitative trait locus; positional and functional candidate gene; single nucleotide polymorphisms; association study; cattle; BTA6 THE DISSECTION of quantitative trait loci (QTL) with impact on complex, economically important traits in livestock and the identification of the underlying genetic variation will help to gain insight into the metabolic pathways and associated genes involved. Concurrently, this will provide the molecular means for a successful marker-assisted selection in livestock populations and may contribute to comparative investigation of basic physiological mechanisms of genetic variation related to similar metabolic pathways and functions of linked and interacting genes in humans and other species. Recently, strategies of comparative positional and functional candidate cloning have been used to identify the molecular background of QTL affecting milk yield and milk composition in dairy cattle and muscle growth in pigs, respectively (e.g., see Refs. 3,18,51,56). A number of independent studies in different populations reported QTL for milk production ...

The primary aim of this study was to investigate whether previous findings of similar quantitative trait loci (QTL) positions for correlated yield traits are due to a pleiotropic QTL. We applied a multitrait variance component based QTL mapping method to a dataset involving five granddaughter families from the German Holstein dairy cattle population. The marker map contained 16 microsatellite markers, distributed across chromosome BTA6. A chromosomewise significance threshold was used, because BTA6 is known to harbor QTL for several milk traits. To evaluate the results from the multivariate, across-family analysis, we also conducted single-family analyses using the least squares method of QTL estimation. The results provided two significant QTL findings at 49 and 64 cM for milk yield in different families and putative QTL at 68 cM for fat yield and at 71 cM for protein yield in another family. The results for fat and protein yield were confirmed by a univariate, across-family variance components analysis. The multivariate analysis of three bivariate trait combinations resulted in a significant pleiotropic QTL finding at 68 cM for fat yield and protein yield, bracketed by markers TGLA37 and FBN13. The estimates of variance contribution due to this QTL were 23% and 25%, respectively.

Interval mapping was carried out to identify quantitative trait loci (QTL) for milk production traits in five granddaughter design families of the German Holstein population. Fourteen randomly generated markers spanning the whole of BTA6 and six targeted microsatellite markers from BTA6q21-31 were included in the analysis. In one family a QTL with effects on milk fat yield and milk protein yield was mapped to the interval TGLA37-FBN13 (3 CM proximal to FBN13, lodscore 3.22) in the middle part of the chromosome. Although there are several reports about QTL with effects on milk production traits on BTA6 in the literature, a QTL with effects on milk fat and milk protein yield has not been previously described.

This study aimed to characterize the intestinal yeasts in weaning piglets and to establish their possible relationships with main bacterial groups. German Landrace piglets were weaned (WP, n=32) at 28 days of age or kept with the dams until day 39 without creep feed (UP, n=32). The experiment was performed at an experimental and a commercial farm (CF). Faeces were collected from the piglets, sows and pen floors on days 28, 33 and 39 for isolation of DNA and cultivation for enumeration of yeasts, enterobacteria, enterococci and lactobacilli. Fragments of the D1 domain of 26S rRNA gene were amplified and separated by denaturing gradient gel electrophoresis (DGGE). No yeasts could be cultured from water and feed samples. No or only low numbers of yeasts were detected among all UP. In WP at CF, yeasts correlated with lactobacilli (r=0.456; P=0.009) and enterobacteria (r=-0.407; P=0.021). Kazachstania slooffiae dominated among the cultured yeasts. It was the only yeast species detected by PCR-DGGE. Yeasts, especially K. slooffiae, established in the porcine gastrointestinal tract after consumption of grain-based feed and may interrelate with the intestinal microbiota. The study provides data indicating importance of K. slooffiae for the development of balanced porcine gut microbiota.