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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.
Opsonic effect of equine plasma from different donors. The ability of equine plasma from different donors to enhance phagocytic capacity was assessed in neutrophils obtained from seven foals, aged 7-8 days (Study A), and from seven adult horses (Study B). Neutrophils were allowed to phagocytize fluorescent yeast cells opsonized with plasma from one of three donors or with pooled serum, all previously frozen (-18 degrees C) and thawed. The results were analysed by flow cytometry. In study A, fresh autologous foal serum was also used for opsonization, and in study B, heat-inactivated plasma and pooled serum were used in addition to untreated samples...
Cloning and analysis of a Borrelia burgdorferi membrane-interactive protein exhibiting haemolytic activity. We cloned the gene encoding a membrane-interactive protein of Borrelia burgdorferi by means of its haemolytic activity in Escherichia coli. The haemolytic activity was erythrocyte-species specific, with progressively decreasing activity for erythrocytes from horse, sheep, and rabbit, respectively. Genetic analysis of the haemolytic determinant revealed two borrelia haemolysin genes, blyA and blyB, that are part of a predicted four-gene operon which is present in multiple copies on the 30 kb circular plasmid(s) of B. burgdorferi B31. blyA encodes a predicted alpha-helical 7.4 kDa protein with a...
Prevalence of the virulence-associated gene of Rhodococcus equi in isolates from infected foals. The prevalence of the plasmid-encoded virulence-associated gene (vapA) of Rhodococcus equi, as determined by PCR, was found to be 98% in isolates from 154 foals with pneumonia, confirming the strong association of vapA with virulence. The vapA genes from 60 representative isolates were compared by digestion with the restriction endonuclease HinfI, and no evidence of sequence variation was detected.
Cloning, sequencing and in vitro functional expression of recombinant donkey follicle-stimulating hormone receptor: a new insight into the binding specificity of gonadotrophin receptors. Among all mammalian FSH receptors (FSH-R; including donkey (dk) FSH-R), only horse (hs) FSH-R does not bind hsLH/chorionic gonadotrophin (CG). In order to delineate the structural origin of hsFSH-R specificity precisely, we have cloned dkFSH-R cDNA from donkey testis mRNA by RT-PCR. Transiently expressed dkFSH-R endowed COS-7 cells with both hsLH/CG- and FSH-binding activity, as well as FSH-induced cAMP production. The deduced dkFSH-R amino acid sequence shares 96% identity with the hsFSH-R: notably, in the hormone-binding domain, the specificity of hsFSH-R may be ascribed to only four diverge...
Fetal calcium homeostasis. The mammalian fetus is maintained hypercalcaemic relative to its mother primarily by the action of a placental calcium pump located in the basal plasma membrane of the trophoblast. It is suggested that the activity of this pump is stimulated by a mid-molecular fragment of parathyroid hormone-related protein [PTHrP(38-94NH2)], produced in the placenta (and also in the parathyroid glands of fetal lambs and calves) as a result of post translational processing. In the sheep, calcitriol is an important determinant of fetal calcium homeostasis and it, too, stimulates the transport of calcium across ...
Characterization and mutational studies of equine infectious anemia virus dUTPase. The macrophage tropic lentivirus, equine infectious anemia virus (EIAV), encodes a dUTPase in the pol gene that is required for efficient replication in macrophages. Two naturally occurring variants of the enzyme were expressed as recombinant proteins in Escherichia coli; metal chelate affinity chromatography was used to purify histidine-tagged recombinant enzymes to greater than 80% homogeneity in a single chromatographic step. Biochemical and enzymatic analyses of these preparations suggest that this method yields dUTPase that is suitable for detailed mutational analysis. Specific activities...
Detection of latency-associated transcripts of equid herpesvirus 1 in equine leukocytes but not in trigeminal ganglia. Results from Southern hybridization and PCR amplification experiments using a randomly synthesized reverse transcription-PCR product showed that peripheral blood leukocytes from horses showing no clinical signs of disease expressed a putative latency-associated transcript antisense to and overlapping the 3' end of the equid herpesvirus 1 (EHV-1) immediate-early gene (gene 64). A PCR product derived from this transcript has > or =96% identity with the published EHV-1 sequence. In situ hybridization studies of equine bronchial lymph nodes corroborated these findings and are consistent with re...
Equine viral arteritis in newborn foals: clinical, pathological, serological, microbiological and immunohistochemical observations. Clinical, pathological, immunohistochemical, serological and microbiological findings are described for 2 geographically and temporally distinct equine arteritis virus (EAV) epidemics in newborn foals. Outbreak A occurred at a commercial Standardbred breeding facility; Outbreak B began in a group of research animals. Clinical signs were severe and primarily referable to the respiratory tract. Fever and leucopenia and/or thrombocytopenia were observed in foals surviving for more than 24 h. The most common gross pathological findings were limited to the respiratory tract. Common histopathologica...
Detection of African horse sickness virus in the blood of experimentally infected horses: comparison of virus isolation and a PCR assay. A reverse transcription-polymerase chain reaction (RT-PCR) assay followed by dot-blot hybridisation was used to detect African horse sickness virus (AHSV); the primers employed amplified the S7 gene that encodes the VP7 protein. The RT-PCR assay was compared with virus isolation for detecting AHSV in blood samples form horses experimentally infected with AHSV-4 and AHSV-9. The influence of sample storage and transportation and the effects of two anticoagulants (EDTA and heparin) were also studied. RT-PCR results were obtained within 48 hours as opposed to a minimum of 15 days for virus isolati...
Expression of the nonstructural protein NS1 of equine influenza A virus: detection of anti-NS1 antibody in post infection equine sera. The nucleotide sequence of the nonstructural protein NS1 of the influenza virus A/equine 2/Suffolk/89 was determined and found to be 97% identical to that of A/equine 2/Miami/63. A similar level of identity was shown for the deduced NS1 amino acid sequence. The NS1 gene was expressed, in its entirety and in part, as fusion proteins with glutathione S-transferase using the pGEX-3X expression vector. Antibodies to NS1 protein were detected in serum samples from ponies experimentally infected with influenza virus, but not in animals vaccinated with whole inactivated virus or in unprimed control a...
Cytokine RNA expression in an equine CD4+ subset differentiated by expression of a novel 46-kDa surface protein. Two monoclonal antibodies (MAb), HB65A (IgG2a) and HB86A (IgGI), recognize a unique cell surface molecule on equine T-lymphocytes. The molecule, designated EqWC4, identified by these MAbs is present on a subpopulation of CD4+ equine lymphocytes (6.3-10.2% of Arabian lymphocytes CD4+ WC4+) and a smaller population of CD8+ lymphocytes (0.5% to 1.2% of Arabian lymphocytes CD8+ WC4+). EqWC4 is absent from B-lymphocytes, granulocytes, and macrophages. Both MAbs bound to a 46-kDa protein following immunoprecipitation reactions with lysates of surface labeled thymocytes. Immunoaffinity purification u...
The effects of ischemia and reperfusion on mucosal respiratory function, adenosine triphosphate, electrolyte, and water content in the ascending colon of ponies. The purpose of this study was to examine the effects of ischemia and reperfusion on the biochemical integrity of equine colonic mucosa to assess the relative roles of ischemic- and reperfusion-induced damage. Methods: Two hours of no-flow ischemia experimentally induced by 720 degrees counterclockwise ascending colon volvulus followed by 2 hours reperfusion after derotation. Methods: Ten ponies. Methods: Ascending colon biopsies were obtained every hour for measurement of mucosal adenosine triphosphate (ATP), water, sodium, and potassium content. Additional samples were homogenized for assay o...
Isolation and characterization of heparin- and phosphorylcholine-binding proteins of boar and stallion seminal plasma. Primary structure of porcine pB1. In the bovine, seminal plasma heparin-binding proteins bind to sperm lipids containing the phosphorylcholine group and mediate the capacitating effects of heparin-like glycosaminoglycans during sperm residence in the female genital tract. We report the characterization of heparin- and phosphorylcholine-binding proteins of stallion and boar seminal plasma. Horse seminal plasma proteins HSP-1 and HSP-2, and boar protein pB1, belong to the same family as the bull heparin- and phosphorylcholine-binding proteins BSP-A1/2, BSP-A3, and BSP-30K. We have determined the amino acid sequence and posttrans...
Cloning, expression, purification, and characterization of the major core protein (p26) from equine infectious anemia virus. The gene coding for the major core protein (p26) of the lentivirus equine infectious anemia virus (EIAV) was cloned from EIAV infected serum, expressed in E. coli, and the resultant protein purified to electrophoretic homogeneity. The protein was expressed in a soluble form and was purified by conventional protein separation methods. When analyzed by SDS-PAGE, under both reducing and non-reducing conditions, the purified protein migrated as a 26 kDa monomer. Recombinant p26 (rp26), therefore, does not contain any intermolecular disulfide bond. Gel filtration chromatography also indicated that ...
A kinase-negative mutation of DNA-PK(CS) in equine SCID results in defective coding and signal joint formation. The equine SCID defect is more severe than its murine counterpart in that SCID foals are incapable of forming either coding or signal joints, whereas SCID mice manifest normal signal joint formation. To determine the basis of this difference and whether DNA-dependent kinase, catalytic subunit (DNA-PK(CS)), is involved in signal joint formation, equine DNA-PK(CS) transcripts were cloned and sequenced from normal and SCID cell lines. In the mutant allele, a frame-shift mutation truncates the protein N terminal of the domain with homology to the phosphatidylinositol 3-kinase family resulting in c...
Intracytoplasmic sperm injection (ICSI) versus conventional IVF on abattoir-derived and in vitro-matured equine oocytes. Conventional IVF as well as several assisted microfertilization techniques have shown limited success in the horse. After recent positive results achieved with intracytoplasmic injection of a single spermatozoon (ICSI) in human IVF, we chose to try the method in the horse. We compared conventional IVF to ICSI by fertilization rates of oocytes with compact and expanded cumuli and by developmental potential of the resulting embryos. Cumulus-oocyte complexes (COCs) were obtained by aspirating the follicular fluid from the ovaries of slaughtered mares. Complexes showing complete cumulus investment...
Leukoencephalomalacia. Leukoencephalomalacia in horses is caused by fumonisins. These mycotoxins are produced by Fusarium spp. that contaminate corn and corn byproducts while in the field. The most common clinical presentation is a multifocal neurologic disease that affects multiple horses in a herd. Although the majority of affected horses die, treatment directed at decreasing inflammation and edema in the CNS may result in recovery in some animals.
In-vitro modulation of plasminogen activator activity, prostaglandin E and nitric oxide production by interleukin-1 in pregnant mare serum gonadotrophin-primed theca-interstitial cells. To examine the participation of the theca-interstitial (TI) compartment in cytokine modulation of ovarian function, the effects of interleukin-1beta (IL-1) on plasminogen activator (PA) activity and on prostaglandin E (PGE) and nitric oxide (NO) production were examined in cultures of pregnant mare serum gonadotrophin (PMSG)-primed rat TI cells. Exposure to IL-1 (10 ng/ml) resulted in a 25% reduction (P < 0.001) in PA activity, concurrent with a 4.6-fold increase in the ability of the corresponding conditioned media to inhibit exogenous urokinase activity. IL-1 also produced a 4.7-fold incr...
White muscle disease of foals. White muscle disease (nutritional myodegeneration) of foals is a peracute to subacute myodegenerative disease affecting skeletal and cardiac muscle. It is caused by a dietary deficiency of selenium and vitamin E, usually in association with predisposing factors such as a high intake of dietary unsaturated fats or unaccustomed exercise. White muscle disease has been observed in foals from birth to 1 year of age, particularly those foals born to dams fed selenium-deficient diets, during gestation. The disease in foals may present as an acute, fulminant syndrome, which is rapidly fatal, or a suba...
Hyperkalemic periodic paralysis. Hyperkalemic periodic paralysis is an autosomal codominant genetic disease of horses who are descendants of the quarter horse sire Impressive. It produces a muscular phenotype that has been selected by show judges, which has resulted in the rapid dissemination of this disease. Clinical attacks are characterized by muscle fasciculation and spasm, and they respond to treatments for the concurrent hyperkalemia.
Insertions, duplications and substitutions in restricted gp90 regions of equine infectious anaemia virus during febrile episodes in an experimentally infected horse. We have studied a horse which exhibited typical clinical signs of disease when experimentally infected with a non-adapted virulent strain of equine infectious anaemia virus (EIAV), designated V70. Five viruses (F1V, F2V, F3V, F4V and F5V) were recovered during periodic febrile episodes. Cross-neutralization tests revealed that all of these variants and the parental V70 were antigenically distinct. Sequencing of their full-length env gp90 genes and gp45 5' sequences revealed novel mutations at a limited number of nucleotide positions, consisting of insertions and duplications in the gp90 princi...
Restriction endonuclease analysis of equine herpesvirus-1 isolates recovered in Ontario, 1986-1992, from aborted, stillborn, and neonatal foals. Ninety-two equine herpesvirus type 1 isolates were recovered from aborted, stillborn, or neonatal foals from Ontario, Canada, from 1986 to 1992. From this total, 32 strains were randomly chosen for further study. Four or 5 isolates from each winter were selected, each from a different premises, and characterized by restriction enzyme analysis using BamHI, KpnI, BglII, HindIII, and EcoRI. Additional isolates from 2 premises and from a zebra foal were also assessed. For the strains isolated in 1986 and 1989-1992, the DNA pattern of 18 strains was similar to that of type 1P (Kentucky D) for BamHI...
Molten globule state of equine beta-lactoglobulin. The acid-unfolded state of equine beta-lactoglobulin was characterized by means of circular dichroism, nuclear magnetic resonance, analytical gel-filtration chromatography, and analytical centrifugation. The acid-unfolded state of equine beta-lactoglobulin has a substantial secondary structure as shown by the far-ultraviolet circular dichroism spectrum but lacks persistent tertiary packing of the side chains as indicated by the near-ultraviolet circular dichroism and nuclear magnetic resonance spectra. It is nearly as compact as the native conformation as shown by the gel filtration and sedime...
