The bovine B and C blood group systems are not likely to be the orthologues of human RH: an interesting twist in the comparative map

Molecular cloning, genetic mapping, and developmental expression of a bovine transforming growth factor beta (TGF-beta) type I receptor

A full-length cDNA encoding the bovine transforming growth factor beta (TGF-beta) receptor type I (bT beta R-I) was isolated from a placenta cDNA library. The deduced protein sequence of 499 residues contains a single transmembrane domain, a cysteinerich extracellular domain, and an intracellular kinase domain with predicted serine/threonine specificity. The amino acid sequence is 96% and 95% identical with its human and mouse homologues, respectively. Genetic mapping assigned the TGFBR1 gene to bovine chromosome 8 at a male genetic distance of 2 centimorgan from D8S28. Assuming conservation of gene order, the linkage data define a breakpoint in mammalian chromosome evolution. Both TGF-beta receptor type I and II mRNAs were found to be expressed in bovine oocytes and preimplantation two-cell, four-cell, eight-cell, morula-, and blastocyst-stage embryos, as determined by heminested reverse transcription polymerase chain reaction (RT-PCR). The mRNA expression patterns of TGF-beta receptor types I, II, and III in a variety of bovine organ tissues were examined by Northern blot hybridization, and highest levels were detected in lung and ovary.

Report of the first workshop on the genetic map of bovine chromosome 23

A report of the first workshop on the genetic map of bovine chromosome 23 (BTA23) is given. Five laboratories contributed data from 29 loci, including a total 11586 informative genotypes. The combined pedigrees represented 1930 potentially informative meioses. Eighteen of the 29 loci were common to two or more data sets and were used to construct a framework linkage map of BTA23. Twelve of the 18 could be ordered on the linkage map with a likelihood ratio of greater than 1000:1. Thus, a low resolution consensus map was constructed with a high level of support for order. The sex-averaged, female and male maps span 54.5, 52.7 and 55.8 cM, respectively. Sex-specific differences in recombination frequency were identified for eight pairs of framework loci. Average genetic distance between framework loci on the sex-averaged map is 5.0 cM.

Isolation and characterization of 45 polymorphic microsatellites from the bovine genome

A small-insert bovine genomic library was constructed in pBluescript II SK(+) and enriched for microsatellites by selective rescue of single-stranded pBluescript DNA carrying (CA)n/(TG)n tandem repeats. Approximately 50% of the clones in the enriched library contained (CA)n repeats or CA-rich sequences. Sequencing of clones selected for (CA)n repeats resulted in the identification and characterization of 45 (CA)n polymorphic microsatellites. Genotyping in 9 large paternal half-sib families indicated that 40 of these microsatellite markers exhibit autosomal Mendelian inheritance. The numbers of alleles range from 2 to 18, with an average of 6.3 per locus. The polymorphic microsatellite markers we have identified and characterized will contribute to the construction of a high-resolution linkage map of bovine genome.

Linkage information content and efficiency of full-sib and half-sib designs for gene mapping

The accuracy of a genetic map depends on the amount of linkage information contained in the data set used for construction of the map. The amount of linkage information is related to the designs employed for linkage analysis. The purpose of this study was to provide general formulations for various genotyping schemes and family structures in order to evaluate the amount of linkage information in a data set. Linkage information content (LIC) was defined as the frequency of fully informative gametes, which are gametes from doubly heterozygous parents with known linkage phases. Depending on the design, LIC is based on two generations if the parental phases are determined statistically, or three generations if the parental phases are determined genetically. Different schemes were considered in deriving LIC: (1) genotyping of one parent or two parents, and (2) genotyping of two or three generation families. The LIC for a full-sib design was found to be generally greater than for a half-sib design but requires typing a large number of individuals when at least one locus has only two alleles. The efficiency of the full-sib design is reduced significantly if a sex-specific linkage map is sought.

A genetic map of nine loci on bovine chromosome 2

A male-specific genetic linkage map of nine loci on bovine Chromosome (Chr) 2 (BTA2) was constructed from 306 offspring belonging to six paternal half-sib families. Loci studied were the structural genes for liver/bone/kidney alkaline phosphatase (ALPL). Gardner-Rasheed feline sarcoma (v-fgr) oncogene homolog (FGR), alpha-L-fucosidase 1 (FUCA1), and fibronectin 1 (FN1), and the microsatellite loci ARO28, DU17S2, DU17S3, DU17S4, and DU17S5. Genotyping was performed by restriction fragment length polymorphism (RFLP) for structural genes and polymerase chain reaction (PCR) for the microsatellites. Two genetically independent linkage groups were identified. The order of genes in the first linkage group, L31, is (ARO28-FN1)-FGR-FUCA1-ALPL, covering a map distance of 34.1 cM between terminal markers. The second linkage group, L32, consists of DU17S2-DU17S5-DU17S4-DU17S3 and is 41.3 cM in length. Genetic linkage between FN1 and FGR confirms previous physical assignment of these genes to the same synteny group. Currently, the genetic linkage of FN1 and FGR is unique to cattle and thus localizes a site of chromosomal evolution to a 22-cM interval between the two loci.