Biomedical subjects

Rosemarie Weikard

Publications and source records attributed to Rosemarie Weikard.

9 recordsLinked to original sources

PubMed2007

Generation of an improved cytogenetic and comparative map of Bos taurus chromosome BTA27.

Comparative genome analysis in cattle, human, and mouse identified various evolutionary breakpoints between Bos taurus 27 chromosome (BTA27) and corresponding segments in the Homo sapiens 4 and 8 chromosomes (HSA4, HSA8) and the Mus musculus 8 chromosome (MMU8). The fragmentary cytogenetic location of breaks is based on nine known loci and Zoo-FISH data on BTA27. A comparative mapping approach combining in-silico mapping and physical mapping by fluorescence in-situ hybridization (FISH) revealed an improved cytogenetic map of BTA27 based on 25 new and nine existing assignments of loci. Furthermore, hybrid cell mapping techniques identified and anchored three additional gene loci on BTA27. The BTA27 map was compared with available mapping and annotated sequence data for the chromosome and a generated comparative map displays conserved syntenic chromosome blocks between cattle, human, and mouse. The new anchor loci identify and narrow down evolutionary breakpoints on a cytogenetic level and can help to support the cattle genome assembly and annotation process.

Animals↗

PubMed2006

A gene-based high-resolution comparative radiation hybrid map as a framework for genome sequence assembly of a bovine chromosome 6 region associated with QTL for growth, body composition, and milk performance traits.

BACKGROUND: A number of different quantitative trait loci (QTL) for various phenotypic traits, including milk production, functional, and conformation traits in dairy cattle as well as growth and body composition traits in meat cattle, have been mapped consistently in the middle region of bovine chromosome 6 (BTA6). Dense genetic and physical maps and, ultimately, a fully annotated genome sequence as well as their mutual connections are required to efficiently identify genes and gene variants responsible for genetic variation of phenotypic traits. A comprehensive high-resolution gene-rich map linking densely spaced bovine markers and genes to the annotated human genome sequence is required as a framework to facilitate this approach for the region on BTA6 carrying the QTL. RESULTS: Therefore, we constructed a high-resolution radiation hybrid (RH) map for the QTL containing chromosomal region of BTA6. This new RH map with a total of 234 loci including 115 genes and ESTs displays a substantial increase in loci density compared to existing physical BTA6 maps. Screening the available bovine genome sequence resources, a total of 73 loci could be assigned to sequence contigs, which were already identified as specific for BTA6. For 43 loci, corresponding sequence contigs, which were not yet placed on the bovine genome assembly, were identified. In addition, the improved potential of this high-resolution RH map for BTA6 with respect to comparative mapping was demonstrated. Mapping a large number of genes on BTA6 and cross-referencing them with map locations in corresponding syntenic multi-species chromosome segments (human, mouse, rat, dog, chicken) achieved a refined accurate alignment of conserved segments and evolutionary breakpoints across the species included. CONCLUSION: The gene-anchored high-resolution RH map (1 locus/300 kb) for the targeted region of BTA6 presented here will provide a valuable platform to guide high-quality assembling and annotation of the currently existing bovine genome sequence draft to establish the final architecture of BTA6. Hence, a sequence-based map will provide a key resource to facilitate prospective continued efforts for the selection and validation of relevant positional and functional candidates underlying QTL for milk production and growth-related traits mapped on BTA6 and on similar chromosomal regions from evolutionary closely related species like sheep and goat. Furthermore, the high-resolution sequence-referenced BTA6 map will enable precise identification of multi-species conserved chromosome segments and evolutionary breakpoints in mammalian phylogenetic studies.

Animals↗

PubMed2006

Amelogenin cross-amplification in the family Bovidae and its application for sex determination.

Sex-specific sequence variability of the amelogenin gene had been observed in a variety of mammalian species. In our study, the suitability of the amelogenin gene for sex determination in different species of the family Bovidae was examined. Based on a sequence insertion/deletion characteristic for X- and Y-specific amelogenin (AMELX and AMELY), PCR amplification on male and female genomic DNA from domestic and wild bovine species, sheep and goat, consistently displayed a sex-specific pattern. Thus, the amelogenin amplification by PCR proved to be a reliable method for sex determination not only in domestic and wild species of the tribe Bovini, but also in the related species sheep and goat. Sex determination using the amelogenin-based assay can be performed with at least 40 pg of genomic DNA. The assay enables the investigation of small amounts of DNA from meat, hair, bones, and embryo biopsies to identify species and sex for a number of applications in animal production, forensics, population research, and monitoring within the family Bovidae. Sequence comparison of the amplified amelogenin gene region specific for male and female animals from domestic and wild bovide species revealed further sequence variations within and between sexes as well as between species. Sequence variations in the AMELX gene can be applied to discriminate Bos and Bison individuals from other bovine species, and also from sheep and goat.

Amelogenin↗

PubMed2005

The bovine PPARGC1A gene: molecular characterization and association of an SNP with variation of milk fat synthesis.

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-gamma coactivator-1alpha 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, 5'- and 3'-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.

Amino Acid Sequence↗

PubMed2004

High-resolution comparative mapping between human chromosomes 4 and 8 and bovine chromosome 27 provides genes and segments serving as positional candidates for udder health in cattle.

To get more information about the order of genes located in Bos taurus (BTA) chromosome 27 segments, supposed to harbor loci influencing clinical mastitis and somatic cell count, and to identify genes that serve as positional candidates for the mentioned traits, we constructed a high-resolution, comparative, and comprehensive gene map for BTA27. The map includes 57 loci in a 5000-rad cattle-hamster whole genome radiation hybrid panel supported by 50 syntenic assignments in a cattle-murine somatic hybrid cell panel. Thirty-eight new loci (36 genes, 2 microsatellites) together with repeated mappings of 5 genes and 7 microsatellites and integration of existing data from 7 microsatellites were used to generate a comprehensive RH5000 map. The RH map, constructed at lod score criterion 8 using the software RHMAP v.3.0, consisted of three linkage groups 23, 22, and 590 cR5000 in length. Gene assignments on BTA27 and the localization of 8 more genes on BTA8 and BTA14 previously predicted on BTA8/BTA27 and BTA14/BTA27 narrowed down significantly the chromosome break points between the three cattle chromosomes and segments on Homo sapiens chromosomes HSA4 and HSA8. Defined evolutionary break points increase the accuracy of comparative in silico mapping of further human genes in conserved chromosome segments of BTA27.

Animals↗

PubMed2004

Targeted generation of 16 sequence-tagged sites for bovine chromosome region 5q21-q25 by microdissection.

The cattle chromosome region BTA5q21-q25 is associated with immune defense and is linked with several economically important traits for growth, ovulation, twinning and milk yield. Chromosome microdissection of the region was performed to generate fragment-specific DNA libraries and to provide new bovine-specific DNA sequences as starting material for physical fine-mapping approaches or linkage studies. A first library screening resulted in the identification of 16 region-specific sequence-tagged sites (STS). Fifteen STS represent new unique cattle DNA sequences, of which one identifies a new microsatellite. Homology with the gene CDK2 was found for the remaining STS.

Animals↗

PubMed2003

The telomeric region of BTA18 containing a potential QTL region for health in cattle exhibits high similarity to the HSA19q region in humans.

We have applied a targeted physical mapping approach, based on the isolation of bovine region-specific large-insert clones using homologous human sequences and chromosome microdissection, to enhance the physical gene map of the telomeric region of BTA18 and to prove its evolutionary conservation. The latter is a prerequisite to exploit the dense human gene map for future positional cloning approaches. Partial sequencing and homology search were used to characterize 20 BACs targeted to the BTA18q2.4-q2.6 region. We used fluorescence in situ hybridization (FISH) to create physical maps of 11 BACs containing 15 gene loci; these BACs served as anchor loci. Using these approaches, 12 new gene loci (CKM, STK13, PSCD2, IRF3, VASP, ACTN4, ITPKC, CYP2B6, FOSB, DMPK, MIA, SIX5) were assigned on BTA18 in the bovine cytogenetic map. A resolved physical map of BTA18q2.4-q2.6 was developed, which encompasses 28 marker loci and a comparative cytogenetic map that contains 15 genes. The mapping results demonstrate the high evolutionary conservation between the telomeric region of BTA18q and HSA19q.

Animals↗

PubMed2002

Targeted construction of a high-resolution, integrated, comprehensive, and comparative map for a region specific to bovine chromosome 6 based on radiation hybrid mapping.

To resolve a candidate chromosome region on the middle part of bovine chromosome 6 (BTA6) containing several different quantitative trait locus (QTL) intervals, we constructed a high-resolution, integrated, comprehensive, and comparative map using a 12,000-rad, whole-genome, cattle-hamster radiation hybrid (RH) panel. The RH map includes a total of 71 loci either selected from bovine and comparative maps or targeted directly from a microdissection library specific for the BTA6 region. All loci typed were placed in one linkage group at a lod score threshold of 4.0. The length of the comprehensive RH map, which is the first high-resolution RH map in cattle, spans 2568.8 cR(12,000). The order of markers obtained principally agrees with the order on published bovine genetic maps. Our RH map integrates markers as well as genes and ESTs available from several physical and genetic maps of BTA6 and the orthologous ovine chromosome 6, human chromosome 4, and mouse chromosomes 5/3. Comparative analysis confirms and refines current knowledge about conservation and rearrangements in corresponding chromosomal regions on BTA6. We identified and localized two new breakpoints for intrachromosomal rearrangements between human chromosome 4 and BTA6. This RH map is a powerful tool in all aspects of genetic, physical, transcript, and comparative mapping. Due to its links to the gene-dense maps of human and mouse, it can serve as a prerequisite to identify possible candidate genes for quantitative trait loci localized in the targeted BTA6 region.

Animals↗

PubMed2002

A comprehensive survey for polymorphisms in the bovine IFN-gamma gene reveals a highly polymorphic intronic DNA sequence allowing improved genotyping of Bovinae.

This study aimed to identify interferon-gamma (IFN-gamma) gene variants in cattle for diagnostic purposes. Therefore, the entire bovine IFN-gamma gene (BoIFNG) and 2605 bp of its promoter DNA were sequenced. The BoIFNG DNA sequence conforms to the published part of Bo-IFN-gamma cDNA. Primer extension experiments show the presence of a 5' extension of exon 1 by 42 nucleotides (nt). One SINE element (Bov-A2) is located in the 5'-region, and two SINE elements (Bov-tA, Bov-B) are contained in the 3'-region of BoIFNG. The variants were detected by comparative sequence analysis of PCR amplicons from different bovine species. Four polymorphic mononucleotide repeats are situated in the promoter and in intron 1. Four distinct series of single nucleotide polymorphisms (SNP) were found in functionally important regions of BoIFNG. The region between the two intron 1 microsatellites contains the highest density of SNPs in Bos taurus breeds. One G-T transversion in the coding region of exon 1 causes a Gly(14) to Val(14) exchange in the BoIFNG signal peptide of different bovine species. A G-A transition in exon 2 encodes a Ser(19) to Asn(19) change in the mature protein of the Tibetan yak. Genotyping of randomly sampled Holstein Friesian cows at selected SNPs and of both intron 1 microsatellites revealed two dominant BoIFNG microhaplotypes. The detected SNPs improve the recently reported genotyping system of cattle.

Amino Acid Substitution↗