Biomedical subjects

F Farnir

Publications and source records attributed to F Farnir.

25 records · Page 2Linked to original sources

PubMed1998

Radiographic assessment of equine interphalangeal joints asymmetry: articular impact of phalangeal rotations (Part I).

This study is part of a work to develop a radiographic method that defines objectively the individual conformation of an equine digit and its appropriate trimming. The authors used isolated distal limbs on a rotation support to study the influence of induced foot rotations on several angles measured from specific radiographs. The results of this work enabled the authors to quantify the rotation of the proximal phalanx compared to the distal, and to determine exactly the possible rotation in the distal interphalangeal joint. It was also observed that, faced with a forced rotation of the foot, the digit responded by a hoof plastic deformity, a distal interphalangeal intra-articular rotation and asymmetrical interphalangeal compressions.

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PubMed1998

Radiographic assessment of equine interphalangeal joints asymmetry: articular impact of asymmetric bearings (Part II).

This study is part of a work to develop a radiographic method that defines objectively the individual conformation of an equine digit and its appropriate trimming. The authors used isolated distal limbs fastened on a rotation support with variable inclinations to study the influence of induced asymmetric bearings on various angles measured from specific radiographs. The digit responded to asymmetric bearings by 1. deformation of the hoof; 2. rotation of the phalanges; and 3. joint asymmetry or local articular space narrowing. The two last situations occurred mainly in the distal interphalangeal joint. Some of the angles mentioned above allow quantification of interphalangeal articular asymmetry, angular deformity and rotational deviation of a distal limb.

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PubMed1997

Towards interbreed IBD fine mapping of the mh locus: double-muscling in the Asturiana de los Valles breed involves the same locus as in the Belgian Blue cattle breed.

The Spanish "Asturiana" cattle breed is characterized by the segregation of a genetically determined muscular hypertrophy referred to as double-muscling or "culones". We demonstrate by linkage analysis that this muscular hypertrophy involves the mh locus previously shown to cause double-muscling in the Belgian Blue cattle breed, pointing towards locus homogeneity of this trait across both breeds. Moreover, using a twopoint and multipoint maximum likelihood approach, we show that flanking microsatellite markers are in linkage disequilibrium with the mh locus in both breeds albeit with different alleles. Finally, we discuss how allelic homogeneity across breeds might be exploited to achieve efficient genetic fine-mapping of the mh locus.

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PubMed1996

Polar overdominance at the ovine callipyge locus.

An inheritable muscular hypertrophy was recently described in sheep and shown to be determined by the callipyge gene mapped to ovine chromosome 18. Here, the callipyge phenotype was found to be characterized by a nonmendelian inheritance pattern, referred to as polar overdominance, where only heterozygous individuals having inherited the callipyge mutation from their sire express the phenotype. The possible role of parental imprinting in the determinism of polar overdominance is envisaged.

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PubMed1996

Effects of character weighting and species sampling on phylogeny reconstruction: a case study based on DNA sequence data in cetaceans.

Different phylogenetic analyses of the same genetic data set can yield conflicting results, depending on the choice of parameter settings and included taxa. This is particularly true in studies involving data sets where levels of homoplasy are high and likely to obscure the phylogenetic signal. Filtering of this phylogenetic noise can be attempted, with varying degrees of success, by using different weighting schemes and ingroup/outgroup choices, but it can be difficult to decide objectively which approach is best. Using a cytochrome b data set from cetaceans and artiodactyls, we examined the effects of a suite of parameter settings on the outcome of phylogenetic analyses. We tested 2968 combinations among the seven parameters that most often vary among phylogenetic studies. It is our contention that this sensitivity analysis identifies portions of the multidimensional parameter space where phylogenetic signal is most reliably recovered, and simple rules are given to guide the choice of settings. Portions of this data set have been used in previous studies with conflicting results, namely the monophyly vs. paraphyly of one of the two major recognized cetacean suborders, the toothed whales. This analysis strongly supports the sister relationship between sperm whales and baleen whales.

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PubMed1996

Identity-by-descent mapping of recessive traits in livestock: application to map the bovine syndactyly locus to chromosome 15.

Twelve animals affected with syndactyly or mulefoot were sampled in the Dutch black-and-white cattle population. Analysis of the pedigree data reveal that all of these individuals traced back to a single acknowledged carrier founder individual. Between seven and nine generations separated the founder from its 12 affected descendents. The 12 affected offspring were genotyped for a battery of 213 microsatellites spanning the 29 bovine autosomes. The resulting genotypes were analyzed using a maximum likelihood approach searching for shared homozygous haplotypes among affected individuals. Three candidate regions for the syndactyly locus emerged from this initial screening. syndactyly was shown to map to one of these candidate regions on chromosome 15 by genotyping 29 additional individuals linking founder and affected offspring and performing a conventional linkage analysis with the LINKAGE programs. This study illustrates the potential of identity-by-descent mapping in livestock populations.

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PubMed1995

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

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 backing "double-muscled (Belgian Blue) x conventional (Friesian)"1 dams to double-muscle 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 respects to a map composed of seven Chr 2-specific microsatellites, at 2 cM from the closet 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 notice 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.

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