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Biomedical subjects

S M Schmutz

Publications and source records attributed to S M Schmutz.

At least 19 recordsLinked to original sources
PubMed2004

The scurs locus in cattle maps to bovine chromosome 19.

Polled, or the absence of horns, is a desirable trait for many cattle breeders. However, the presence of scurs, which are small horn-like structures that are not attached to the skull, can lower the value of an animal. The scurs trait has been reported as sex influenced. Using a genome scan with 162 autosomal microsatellite markers genotyped across three full-sib families, the scurs locus was mapped near BMS2142 on cattle chromosome 19 (LOD = 4.21). To more precisely map scurs, the families from the initial analysis and three additional families were genotyped for 16 microsatellite markers and SNPs in three genes on chromosome 19. In this subsequent analysis, the scurs locus was mapped 4 cM distal of BMS2142 (LOD = 4.46) and 6 cM proximal to IDVGA46 (LOD = 2.56). ALOX12 and MFAP4 were the closest genes proximal and distal, respectively, to the scurs locus. Three microsatellite markers on the X chromosome were genotyped across these six families but were not linked to scurs, further demonstrating that this trait was not sex linked. Because the polled locus has been mapped to the centromeric end of chromosome 1 and scurs has now been mapped to chromosome 19, these two traits are not linked in Bos taurus.

Agriculture↗
PubMed2003

TYRP1 is associated with dun coat colour in Dexter cattle or how now brown cow?

Tyrosinase related protein 1 (TYRP1), which is involved in the coat colour pathway, was mapped to BTA8 between microsatellites BL1080 and BM4006, using a microsatellite in intron 5 of TYRP1. The complete coding sequence of bovine TYRP1 was determined from cDNA derived from skin biopsies of cattle with various colours. Sequence data from exons 2-8 from cattle with diluted phenotypes was compared with that from non-diluted phenotypes. In addition, full-sib families of beef cattle generated by embryo transfer and half-sib families from traditional matings in which coat colour was segregating were used to correlate TYRP1 sequence variants with dilute coat colours. Two non-conservative amino acid changes were detected in Simmental, Charolais and Galloway cattle but these polymorphisms were not associated with diluted shades of black or red, nor with the dun coat colour of Galloway cattle or the taupe brown colour of Braunvieh and Brown Swiss cattle. However, in Dexter cattle all 25 cattle with a dun brown coat colour were homozygous for a H424Y change. One Dexter that was also homozygous Y434 was red because of an "E+/E+" genotype at MC1R which lead to the production of only phaeomelanin. None of the 70 remaining black or red Dexter cattle were homozygous for Y434. This tyrosine mutation was not found in any of the 121 cattle of other breeds that were examined.

Animals↗
PubMed2003

Hot topic: an association between a leptin single nucleotide polymorphism and milk and protein yield.

Allelic variation (C to T transition that results in an Arg25Cys) in the leptin gene has been associated with increased fat deposition in beef cattle. We report that this same genetic variant is also present in dairy breeds. Body fat reserves play an important role in sustaining high milk production in early lactation, when energy intake is limited. To test for an association between the leptin single nucleotide polymorphism and milk productivity, we genotyped 416 Holstein cows and compared lactation performance data using a mixed model. Animals homozygous for the T allele produced more milk (1.5 kg/d vs. CC animals) and had higher somatic cell count linear scores, without significantly affecting milk fat or protein percent over the entire lactation. The increase in milk yield is most prominent in the first 100 d of lactation (2.44 kg/d), declining to 1.74 kg/d between 101 and 200 d in lactation. The milk yield advantage, observed in cows homozygous for the T allele, could represent a major economic advantage to dairy producers.

Alleles↗
PubMed2002

Consensus and comprehensive linkage maps of bovine chromosome 24.

This study describes development of a consensus genetic linkage map of bovine chromosome 24 (BTA24). Eight participating laboratories contributed data for 58 unique markers including a total of 25 409 meioses. Eighteen markers, which were typed in more than one reference population, were used as potential anchors to generate a consensus framework map. The framework map contained 16 loci ordered with odds greater than 1000:1 and spanned 79.3 cM. Remaining markers were included in a comprehensive map relative to these anchors. The resulting BTA24 comprehensive map was 98.3 cM in length. Average marker intervals were 6.1 and 2.5 cM for framework and comprehensive maps, respectively. Marker order was generally consistent with previously reported BTA24 linkage maps. Only one discrepancy was found when comparing the comprehensive map with the published USDA-MARC linkage map. Integration of genetic information from different maps provides a high-resolution BTA24 linkage map.

Animals↗
PubMed2001

Development of the Canadian beef reference herd for gene mapping studies.

A project to map quantitative trait loci (QTL), in beef cattle using a full-sib design was initiated using six Bos taurus breeds. Embryo transfer was used in a large scale, short timeframe experiment to develop this herd for gene mapping. Full-sib families allowed for genetic information to be followed through both the sire and the dam and for both parents to be slaughtered so that carcass quality data could also be obtained from both of them at close to typical slaughter ages. Repeatability of response to superovulation was significant among the 3 flushes per female. Response to superovulation was negatively correlated with backfat of the donor. Crossbred embryos were found to have higher survival than purebred embryos.

Adipose Tissue↗
PubMed2001

Comprehensive linkage map of bovine chromosome 27.

The results of genotypic data contributed to the International Society for Animal Genetics (ISAG) Bovine Chromosome 27 Workshop are presented. Eight laboratories contributed 23 261 informative meioses from 44 loci. Eighteen loci were typed by at least two laboratories and were used to construct a consensus linkage map. Twenty-one loci were subsequently incorporated into a comprehensive map. The sex-averaged consensus map covered 66.9 cM. The sex-averaged comprehensive map was 75.5 cM, while the female and male maps were 73.1 and 63.7 cM, respectively. Five loci were excluded from the analysis because of ambiguous position in the linkage group and a low LOD score (less than 2.0). Average distance between loci in the comprehensive map was 1.98 cM.

Animals↗
PubMed2001

Comprehensive linkage map of bovine chromosome 11.

The results of genotypic data contributed to the International Society of Animal Genetics (ISAG) Bovine Chromosome 11 (BTA11) Workshop are presented. Six laboratories contributed a total of 26 199 informative meioses from 80 loci. Thirty-six loci were typed by at least two independent laboratories and were used to construct a consensus linkage map of the chromosome. The remaining loci were subsequently incorporated into a comprehensive map. The sex-averaged consensus map covered 128.9 cM. The female consensus map was 101.2 cM, while the male consensus map was 129.8 cM. The comprehensive sex-averaged map was 134.2 cM and the average genetic distance between loci was 1.72 cM.

Animals↗