The mh gene causing double-muscling in cattle maps to bovine chromosome 2

in Mammalian Genome : Official Journal of the International Mammalian Genome Society (1995), 6

While the hereditary nature of the double-muscling phenotype (a generalized muscular hypertrophy documented in several cattle breeds) is well established, its precise segregation mode has remained ... [more ▼]

While the hereditary nature of the double-muscling phenotype (a generalized muscular hypertrophy documented in several cattle breeds) is well established, its precise segregation mode has remained controversial. Both monogenic models (autosomal dominant or recessive) and oligogenic models have been proposed. Using a panel of 213 bovine microsatellite markers, and an experimental pedigree obtained by backcrossing double-muscled (Belgian Blue)xconventional (Friesian) F1 dams to double-muscled sire, we have mapped a locus on bovine Chromosome (Chr) 2 that accounts for all the phenotypic variance in the backcross generation. This locus, referred to as mh (muscular hypertrophy), has been positioned with respect to a map composed of seven Chr 2-specific microsatellites, at 2 cM from the closest marker. This result confirms the validity in the Belgian Blue population of the monogenic model involving an autosomal mh locus, characterized by a wild-type + and a recessive mh allele, causing the double-muscling phenotype in the homozygous condition. The linkage relationship between the mh locus and the Chr 2 markers was confirmed in three informative pedigrees collected from the general Belgian Blue Cattle population, reinforcing the notion of genetic homogeneity of the double-muscling trait in this breed. This work paves the way towards marker-assisted selection for or against the double-muscling trait, and towards positional cloning of the corresponding gene. [less ▲]

Chromosomal localization of the callipyge gene in sheep (Ovis aries) using bovine DNA markers

in Proceedings of the National Academy of Sciences of the United States of America (1994), 91

A mutation causing muscular hypertrophy, with associated leanness and improved feed efficiency, has been recently identified in domestic sheep (Ovis aries). Preliminary results indicate that an autosomal ... [more ▼]

A mutation causing muscular hypertrophy, with associated leanness and improved feed efficiency, has been recently identified in domestic sheep (Ovis aries). Preliminary results indicate that an autosomal dominant gene may be responsible for this economically advantageous trait. We have exploited the conservation in sequence and chromosomal location of DNA markers across Bovidae to map the corresponding callipyge locus to ovine chromosome 18 using a battery of bovine chromosome 21 markers. Chromosomal localization of the ovine callipyge locus is the first step toward positional cloning of the corresponding gene. [less ▲]

Construction of a bovine genomic library of large yeast artificial chromosome clones

in Genomics (1993), 18(2), 270-276

We have constructed a yeast artificial chromosome (YAC) library derived from bull fibroblasts in primary culture. The library consists of 21,500 clones arranged on 224 gridded plates (96 or 8×12 positions ... [more ▼]

We have constructed a yeast artificial chromosome (YAC) library derived from bull fibroblasts in primary culture. The library consists of 21,500 clones arranged on 224 gridded plates (96 or 8×12 positions) and in 2×224 96-well microplates maintained as permanent frozen stocks. An average insert size of 750 kb was estimated from the analysis of 200 randomly selected YACs, giving a sixfold coverage of the bovine genome for the total library. A screening strategy based on the polymerase chain reaction that allows the identification of individual clones has been devised. Screening of the library with six locus-specific markers of interest led to the isolation of 34 positive clones [less ▲]

Quantitative estimation of chimerism in mice using microsatellite markers

in Molecular Reproduction and Development (1993), 34(2), 127-132

An embryonic stem cell line was established from SV129 mouse blastocysts and used to generate chimeric mice by injection into OF1 blastocysts; 18 out of the 30 resulting offspring appeared chimeric as ... [more ▼]

An embryonic stem cell line was established from SV129 mouse blastocysts and used to generate chimeric mice by injection into OF1 blastocysts; 18 out of the 30 resulting offspring appeared chimeric as judged from their coat color patterns, and 3 of the 13 males proved to be germ-line chimeras as they transmitted the SV129 agouti phenotype to all or part of their offspring. The degree of chimerism of these males was evaluated for different tissues using polymorphic microsatellite markers amplified by the polymerase chain reaction. It was shown that these new markers can be effectively used to quantitatively estimate levels of chimerism. The CKMM (creatine kinase, muscle) microsatellite system was used to distinguish the SV129 from the OF1 genotype. In all performed tests, the correlation between DNA ratio and signal ratio, expressed as a base 10 logarithm, was shown to exceed or equal 0.98 for known DNA ratios (SV129/OF1) ranging from 1/99 to 99/1. Linear calibration methods were used to predict the % SV129 DNA of a test sample based on the obtained signal ratio. The accuracy of the prediction was evaluated by performing repeated measurements. Differences among three repeated estimates ranged from 2 to 17% for a given sample. Microsatellite systems should be very useful to monitor chimerism involving strains that can not be discerned with coat color or biochemical markers. This will be particularly important when ES methodology becomes available in species other than mice. [less ▲]

The effects of selection on linkage analysis for quantitative traits

in Genetics (1992), 132

The effects of within-sample selection on the outcome of analyses detecting linkage between genetic markers and quantitative traits were studied. It was found that selection by truncation for the trait of ... [more ▼]

The effects of within-sample selection on the outcome of analyses detecting linkage between genetic markers and quantitative traits were studied. It was found that selection by truncation for the trait of interest significantly reduces the differences between marker genotype means thus reducing the power to detect linked quantitative trait loci (QTL). The size of this reduction is a function of proportion selected, the magnitude of the QTL effect, recombination rate between the marker locus and the QTL, and the allele frequency of the QTL. Proportion selected was the most influential of these factors on bias, e.g., for an allele substitution effect of one standard deviation unit, selecting the top 80%, 50% or 20% of the population required 2,6 or 24 times the number of progeny, respectively, to offset the loss of power caused by this selection. The effect on power was approximately linear with respect to the size of gene effect, almost invariant to recombination rate, and a complex function of QTL allele frequency. It was concluded that experimental samples from animal populations which have been subjected to even minor amounts of selection will be inefficient in yielding information on linkage between markers and loci influencing the quantitative trait under selection. [less ▲]

Data analysis for linkage studies

in Schook, L. B.; Lewin; McLaren (Eds.) Gene Mapping: strategies, techniques and applications (1991)

Hypervariable Minisatellites and their use in animal breeding

in Schook, L. B.; Lewin; McLaren (Eds.) et al Gene Mapping: strategies, techniques and applications (1991)

Perspectives for marker assisted selection and velogenetics in animal breeding

in Pedersen; McLaren; First (Eds.) Animal Applications of Research in Mammalian Development (1991)

Linkage Relationships among 20 Genetic Markers in Cattle. Evidence for Linkage between Two Pairs of Blood Group Systems: B-Z and S-F/V Respectively

in Animal Genetics (1990), 21(2), 95-105

Five bovine paternal half-sib pedigrees for a total of 527 individuals were typed for six blood group systems: A, B, F/V, L, S, Z; for nine biochemical polymorphisms: ADA, MPI, PGM-3(slow), NP, Gc, Pi2 ... [more ▼]

Five bovine paternal half-sib pedigrees for a total of 527 individuals were typed for six blood group systems: A, B, F/V, L, S, Z; for nine biochemical polymorphisms: ADA, MPI, PGM-3(slow), NP, Gc, Pi2, Tf, Ptf1 and Ptf2; and for restriction fragment length polymorphisms at five autosomal loci: Tg, GH, LDLr, BoLA-DQ and BoLA-DY. Two of the pedigrees were informative for segregation at the 'muscular hypertrophy' locus, and one was informative at the coat colour determining 'roan' locus. Linkage analysis was performed between all markers. Linkage was demonstrated between the S and F/V blood group systems (z = 3.11), adding one locus to the previously identified linkage group VII (LGVII) [Pi-2 and S], the most likely order being Pi2-S-F/V with maximum likelihood recombination rates of 0.208 and 0.211. Also shown to be linked were the blood group systems B and Z (z = 5.7, theta = 0.245). We confirmed the observation previously made by Andersson et al. (1988) of a high recombination rate between class II genes DQ and DY, suggesting either a larger physical distance between those genes than expected from comparative data, or the presence of a 'recombinational hotspot' in the bovine major histocompatibility complex. No linkage was found either with the 'muscular hypertrophy' locus, or with the 'roan' locus. However, these two loci could be excluded from respectively 1.7 and 2.5 Morgans of the bovine genome. [less ▲]

Analysis of genetic variation in the Belgian Blue Cattle Breed using DNA sequence polymorphism at the growth hormone, low density lipoprotein receptor, -subunit of glycoprotein hormones and thyroglobulin loci

in Animal Genetics (1989), 20

New DNA sequence polymorphisms were identified at four bovine autosomal loci: growth hormone, low density lipoprotein receptor, alpha-subunit of glycoprotein hormones and thyroglobulin. Assuming ... [more ▼]

New DNA sequence polymorphisms were identified at four bovine autosomal loci: growth hormone, low density lipoprotein receptor, alpha-subunit of glycoprotein hormones and thyroglobulin. Assuming independent assortment between these polymorphisms, the probabilities to be heterozygous at these four loci are 0.48, 0.36, 0.10 and 0.77 respectively, within the Belgian Blue Cattle breed (BBCB). Nucleotide diversity was estimated, showing that animals from the BBCB are heterozygous for 1/1450 nucleotides, a value significantly lower than the 1/500 value found in man. Moreover, we have estimated that the mutation rate at the cytosines of CG dinucleotides is about 10 times higher than that for other nucleotides. [less ▲]