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Topic:Genetics
Genetics in horses encompasses the study of hereditary traits and the genetic makeup that influences various characteristics and health conditions in equine populations. This field involves the analysis of genes and their functions, inheritance patterns, and the impact of genetic variations on traits such as coat color, performance ability, and susceptibility to diseases. Research in equine genetics employs techniques such as genome mapping, sequencing, and genetic testing to identify specific genes and mutations associated with these traits. This page gathers peer-reviewed research studies and scholarly articles that explore the genetic basis of equine traits, the methodologies used in genetic research, and the implications for breeding, health management, and conservation of horse breeds.
Selection of a strain of Culex tarsalis highly resistant to infection following ingestion of western equine encephalomyelitis virus. After prolonged selection, two hybrid strains of Culex tarsalis were evolved that were highly resistant to infection following ingestion of western equine encephalomyelitis virus. These strains were greater than 25,000-fold more resistant than the most susceptible parental strain when fed on viremic chicks. Resistance was associated with a mesenteronal barrier since both refractory and parental strains were equally susceptible to infection by intrathoracic inoculation. Susceptibility was dominant, possibly incompletely dominant, over resistance. Inheritance was probably polyfactorial but this ...
Microculture method for mixed lymphocyte cultures in the horse. A miniaturized method for the mixed lymphocyte culture test in the horse is described. The test is performed in either round- or flat-bottom microtitration tissue culture plates. Concentrations of responsing and stimulating cells are varied, depening on the experiment. Significant discrimination between isogeneic and allogenic mixtures is possible after 120 hours' culture when cells are labeled ([3H]thymidine) for the last 16 to 18 hours of the test.
Circular dichroic properties and conformation of thionicotinamide dinucleotides bound to horse-liver alcohol dehydrogenase. The interaction between horse liver alcohol dehydrogenase and the oxidized and reduced forms of the 3-thionicotinamide--adenine dinucleotide coenzyme analogues (sNAD and sNADH) has been investigated by ultraviolet absorption, fluorescence and circular dichroism. The fluorescence of sNADH is enhanced when bound to the enzyme, and the protein fluorescence is quenched by both sNADH (60--65%) and sNAD (65%). The possible origin of the larger quenching produced by sNAD with respect to that of NAD is discussed. Coenzyme dissociation constants have been determined by monitoring the quenching of the p...
Immunoglobulins and secretory component in the external secretions of foals with combined immunodeficiency. Nasal washings and tears were collected from seven Arabian foals with combined immunodeficiency and nine normal foals. The major immunoglobulin in the external secretions of normal foals over 2 months of age was secretory immunoglobulin A, whereas foals with combined immunodeficiency lacked this immunoglobulin. The external secretions of both normal and immunodeficient foals contained free secretory component at birth.
Mixed lymphocyte culture responses in combined immunodeficiency of horses. Combined immunodeficiency in horses is a genetic disorder in which there is a defect in the production of committed B and T lymphocytes. In this study, peripheral blood mononuclear leukocytes from foals with combined immunodeficiency were examined for their capacity to stimulate and respond in one-way mixed lymphocyte cultures. Irradiated cells from combined immunodeficient foals were uniformly capable of stimulating cells from unrelated horses. However, none were able to respond to allogeneic stimulation. Examination of cells from known carrier horses revealed no difference in capacity to sti...
[Immunochemical investigations on the gene expression of horse serum carboxylesterase (author’s transl)]. Immunochemical and enzymatic analyses of horse serum carboxylesterase were carried out with respect to the existence of a silent gene. Sera with positive phenotypic expression of esterase, both heterozygotes and presumed homozygotes, were compared with:--sera with positive phenotypic expression but genotypically +/O;--sera with a negative phenotypic expression, i. e. genotypically O/O;--sera of natural +/O "hemi-zygotes": mules (donkey lacking the esterase);--positive sera heated at 60 degrees C;--positive sera after specific inhibition of enzymatic activity. Titration by immunocompetition has...
Synthetic antigens. Horse “natural” antibodies against interpolymer of styrene and maleic acid (PSM). Properties of horse natural anti-PSM antibodies are described. The antibodies were of IgG class. Electrostatic forces were mainly involved in reaction of PSM with horse antibodies. The reaction was inhibited by low molecular compounds resembling structural unit of PSM. Studies of difference spectra and ORD and CD spectra showed no major conformational changes in horse antibodies after reaction with PSM.
A new allele in the prealbumin system of horse serum markers. A family study of an index case in the Arabian breed of horses demonstrated the presence of a new allele in the prealbumin (Pr) system of electrophoretically determined markers in horse serum which, when homozygous, results in the absence of any recognizable zones in the Pr region. The symbol PrO is proposed for this allele which has an estimated frequency in Arabian horses of 0.09.
Equine markers genes. Polymorphism for group-specific component (Gc). Polymorphism of equine Gc protein was demonstrated by immunofixation electrophoresis with a goat anti-human Gc antibody. Three different phenotypes, F, FS and S, were found. Family data supported the genetic theory of two autosomal codominant alleles, GcF and GcS. Both alleles occurred in Standardbred, Thoroughbred and Arabian horses and in Shetland ponies. A frequency of 0.23 for GcS in the American Standardbred horse indicates the system should be useful for problems of identification and parentage.
Isoelectric focusing of horse serum esterase isozymes and detection of new phenotypes. A new method for separating the isozymes of horse serum esterase is described. The improved resolution has enabled us to detect several previously undescribed phenotypes. This method has also been used to detect two different apparently 'silent' alleles.
Close linkage between the albumin and Gc loci in the horse. Evidence for close linkage between the structural loci for albumin and Gc protein in the horse was presented. A recombination frequency (c) of 0.009 +/- 0.006 (95% confidence limits: 0.001 less than c less than 0.032) was estimated. These results were based on a study of a large sire family comprising 223 offspring from informative matings. No evidence of linkage disequilibrium was observed in one horse population studied.
Horner’s syndrome in the horse: experimental induction and a case report. The findings in 6 experimental and 1 natural case of Horner's Syndrome (HS) are presented. The experimental cases were induced by unilateral surgical section of the cervical sympathetic trunk in the middle third of the neck. The naturally occurring case was seen in a 17 year old gelding with a mediastinal tumour. The signs of HS in these horses included ptosis, miosis, enophthalmos, hemilateral sweating and temperature increase of the face and cranial cervical region on the affected side. The intensity of these signs was variable between and within animals. Miosis, enophthalmos and temperature...
Common and species-specific esterases of Equidae–IV. Horse of przewalski, onager and Zebra hartmannae. 1. Among several species of Equidae only E. przewalskii possesses a serum esterase identical with that of E. caballus. 2. The esterases of Hemionidae differ slightly from that of domestic horse by electrophoretic migration and by antigenic structure. 3. Zebras (grevyi, burchelli) appear devoid of this component but Z. hartmannae possesses an esterase of high enzymatic activity, differing notably from that of horse by electrophoretic and antigenic properties.
The ‘normal range’ and precision of phytohaemagglutinin-induced equine lymphocyte transformation in vitro. Data are presented on lymphocyte transformation by phytohaemagglutinin in 20 normal horses. The logarithms of transformation ratios were found to have an approximately normal distribution, giving (for the transformation ratios themselves) a geometric mean of 23.6, a range of 1.92 to 97.3, and an estimated 95 per cent tolerance interval of 1.1 to 488. Analysis of variance on the logarithms of the transformation ratios gave a coefficient of variation of 140 per cent of the transformation ratios themselves for the variation between horses; whereas the coefficient of variation between duplicate sa...
Factors influencing the quantity and quality of semen harvested from bulls, rams, boars and stallions. Several inherited conditions associated with testicular defects, abnormal spermatogenesis and morphologically abnormal sperm have been found. These usually are controlled by single gene pairs. A notable exception is testicular size, with heritability in young bulls ranging from .42 to .88. Testicular size directly affects sperm output potential. The major contributor to variation in semen quality is the environment. Environmental effects may be temporary or permanent. Permanent effects occurring during prenatal and prepubertal periods and temporary or permanent factors acting after spermatogen...
Polymorphic post-albumin of cattle and horse plasma identified as vitamin D binding protein (Gc protein). Cattle and horse plasma samples of known post-albumin types were radiolabelled with 14C-vitamin D3. These samples were then analysed by polyacrylamide gel electrophoresis, followed by autoradiography. The patterns observed were identical to those of post-albumin variants. The polymorphic post-albumin protein of cattle and horse was thus identified as the vitamin D binding protein and homologous to the Gc protein of human plasma.
Genetic polymorphism of the vitamin D binding protein and another post-albumin protein in horse serum. Horizontal polyacrylamide gel electrophoreses, on 10% separation gel, of horse serum revealed polymorphism of the vitamin D binding protein (Gc protein) and another post-albumin protein (Pa). Family data supported the hypothesis that Gc and Pa types were controlled by autosomal codominant alleles. For both Gc and Pa proteins, the homozygous types showed a single fraction while the heterozygous type had two fractions. Pa types were found to be identical to the post-albumin types reported earlier by starch gel electrophoresis. Two Gc alleles, GcF and GcS, and three Pa alleles, Pa D, Pa F and Pa ...
