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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.
Development of PCR assays to detect genetic variation amongst equine herpesvirus-1 isolates as an aid to epidemiological investigation. A search for variable restriction sites has been carried out for equine herpesvirus-1 (EHV-1) in an attempt to develop markers which can be used to group epidemiologically related viruses into groups, and to learn more about the dynamics of EHV-1 disease. Crude viral DNA extracts of EHV-1, prepared by Hirt extraction, were digested with AluI, HaeIII, or RsaI, and Southern blotted following electrophoresis. DNA fingerprints, produced by probing the Southern blots with the EHV-1 EcoR1-I fragment, separated 56 isolates into 16 groups. The variable sites within the EcoR1-I fragment were mapped app...
Accumulation of chromotrope 2R positive cells in equine endometrium during early pregnancy and expression of transforming growth factor-beta 2 (TGF-beta 2). Endometrial tissue from the gravid uterine horn of pregnant mares was examined by northern analysis and in situ hybridization for mRNA that hybridized to cDNA and RNA probes generated from a mouse TGF-beta 2 1.2 kb cDNA clone. The mouse cDNA probe hybridized to characteristic TGF-beta 2 mRNA transcripts on a northern blot of total RNA isolated from horse endometrium collected at day 45 of gestation. Two major 4.0 and 3.5 kb transcripts and possibly a minor 1.6 kb transcript were observed, consistent with specific hybridization to equine TGF-beta 2 mRNA. By in situ hybridization, riboprobes tra...
Influence of stochastic events on the phenotypic variation of common white leg markings in the Arabian horse: implications for various genetic disorders in humans. One method of assessing the influence of stochastic events on phenotypic variation is to study morphological differences in paired limbs of the same individual. These limbs have identical genotypes and similar intra-uterine environments and are analogous to monozygotic twins. Common white leg markings have a multifactorial mode of inheritance in the Arabian horse. Asymmetry occurs frequently for these markings. Using computerized registration records obtained from the Arabian Horse Registry of America, Inc., the types of markings were quantified in the left foreleg and left hind leg of bay and...
Enhanced sensitivity to neutralizing antibodies in a variant of equine infectious anemia virus is linked to amino acid substitutions in the surface unit envelope glycoprotein. Serial passage of the prototype (PR) cell-adapted Wyoming strain of equine infectious anemia virus (EIAV) in fetal donkey dermal (FDD) rather than fetal horse (designated fetal equine kidney [FEK]) cell cultures resulted in the generation of a variant virus strain which produced accelerated cytopathic effects in FDD cells and was 100- to 1,000-fold more sensitive to neutralizing antibodies than its parent. This neutralization-sensitive variant was designated the FDD strain. Although there were differences in glycosylation between the PR and FDD strains, passage of the FDD virus in FEK cells di...
Horse trophoblasts produce tumor necrosis factor alpha but not interleukin 2, interleukin 4, or interferon gamma. The distribution of four cytokines was analyzed in the endometrium and trophoblast of the horse between Days 30 and 55 of gestation. Endometrial tissues, invasive trophoblast (chorionic girdle), and noninvasive trophoblast (chorion and allantochorion) were examined separately. Cytokine expression was determined by amplification of specific mRNA via the reverse transcriptase polymerase chain reaction (RT-PCR). Messenger RNA for interleukin 2 (IL-2), interleukin 4 (IL-4), and interferon gamma (IFN gamma) was detected in endometrial tissues, unstimulated peripheral blood lymphocytes, and control ...
An 80-kDa syncytiotrophoblast alloantigen bound to maternal alloantibody in term placenta. We have shown that most of the IgG present on term syncytiotrophoblast, membrane, microvesicles is bound to an 80 kDa protein antigen (R80K). Methods: Microvesicles were prepared from term human placenta, and the IgG eluted at pH3. Results: When IgG antibody was eluted at pH3 and reacted with acid-treated vesicles of other placentae, the alloantibody always bound to the preparation from which it was obtained, but only to about 10% of acid-treated preparations from other placentae. A similar polymorphic protein found in association with IgG antibody was found in term horse placentae. Cross-reac...
Regulation of granule size in human and horse eosinophils by number of fusion events among unit granules. 1. We have investigated the granule size distributions in human and horse eosinophils by time-resolved patch-clamp capacitance measurements. 2. During exocytosis of single granules the electrical capacitance of the plasma membrane increases in discrete steps. The steps in horse cells are about six times larger than those in human cells in accordance with the difference in granule size. 3. In both species a multimodal capacitance step size distribution is observed with a first peak at 6-7 fF corresponding to granules with a diameter of about 450-500 nm and a surface area of about 0.7 microns2, ...
The proximal ligand variant His93Tyr of horse heart myoglobin. The spectroscopic and structural properties of the His93Tyr variant of horse heart myoglobin have been studied to assess the effects of replacing the proximal His residue of this protein with a tyrosyl residue as occurs in catalases from various sources. The variant in the ferric form exhibits electronic spectra that are independent of pH between pH 7 and 10, and it exhibits changes in absorption maxima and intensity that are consistent with a five-coordinate heme iron center at the active site. The EPR spectrum of the variant is that of a high-spin, rhombic system similar to that reported for...
Changes in equine endometrial retinol-binding protein RNA during the estrous cycle and early pregnancy and with exogenous steroids. A cDNA library was constructed from poly(A) RNA obtained from Day 14 nonbred equine endometrium. A cDNA probe for porcine retinol-binding protein (RBP) was used to screen the library, and a complete cDNA sequence (1133 bp, excluding the poly(A) tail) was obtained. Endometrial biopsies were obtained from cycling, nonbred mares at Days 0, 1, 4, 8, 10, 11, 13, and 15 and from pregnant mares at Days 11, 13, 15, and 17 after ovulation (n = 2 mares each day). Endometrial biopsies were also taken from 18 noncycling anestrous mares after the following treatments: C (vehicle control for 1 day, n = 3), ...
Unusual D system inheritance in Anglo-Arab horse. An unusual D system phenogroup appeared in one family line of Anglo-Arab horse. This phenogroup probably originated from inheritance with an apparent absence of factors and was transmitted through successive generations.
Morphology and location of attached follicular cumulus-oocyte complexes in horses, cattle and llamas. Morphology and location of the attached cumulus-oocyte complex (COC) were studied in slaughter-house ovaries in horses (49 follicles, 9 to 44 mm), cattle (68 follicles, 6 to 18 mm), and llamas (38 follicles, 3 to 14 mm). The expected point of ovulation was marked, using the ovulation fossa in mares and the center of the projecting follicular surface in cattle and llamas. A follicle was dissected from an ovary, and tissue was removed from the follicle until the COC became visible by transillumination. However, most llama follicles protruded prominently from the ovarian surface so that dissectio...
Plasmid profiles of Klebsiella pneumoniae isolated from horses. Plasmid profiles of Klebsiella pneumoniae isolated from horses were examined. Thirty-nine strains of K. pneumoniae capsular type 1 (K1) isolated from cervical swabs of mares suffering from metritis, and from semen of stallions showed similar plasmid profile patterns, and all strains possessed a 125 megadaltons (Md) plasmid. There was no difference in plasmid profiles between the heavily-encapsulated and the less heavily-encapsulated strains of K. pneumoniae K1. Non-capsulated variants derived from the strains of K1 showed the same plasmid profile pattern as the parent strains. Plasmid profiles...
Characterisation of a membrane receptor on ruminants and equine platelets and peripheral blood leukocytes similar to the human integrin receptor glycoprotein IIb/IIIa (CD41/61). This paper describes two anti-glycoprotein IIb/IIIa or CD41/61 murine monoclonal antibodies (Co.35E4 and Co.2oA1). The cellular distribution and apparent molecular weight of the antigen detected by these antibodies is consistent with their reaction with ruminant and equine glycoprotein IIb/IIIa. Biochemical analysis of the equine molecule using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) revealed bands of 24, 100 and 110 kDa under reducing conditions and 115 and 80 kDa under nonreducing conditions. Biochemical analysis of ruminant antigen revealed that the 24 kDa band...
Localization of a protective epitope on a Venezuelan equine encephalomyelitis (VEE) virus peptide that protects mice from both epizootic and enzootic VEE virus challenge and is immunogenic in horses. In order to define more precisely the protective epitope encoded within the first 25 amino acids (aa) of the E2 glycoprotein of the Trinidad donkey strain of Venezuelan equine encephalomyelitis (VEE) virus, we examined the immunogenicity of smaller peptides within the first 19 aa. pep1-9 and pep3-10 elicited virus-reactive antibody, but failed to protect mice from virus challenge. Additionally, pep3-10 was identified by a competitive binding assay using overlapping peptide octamers as the putative binding site of the antipeptide monoclonal antibody (mAb) 1A2B-10. Since the E2 amino-terminal se...
Electrostatics of hemoglobins from measurements of the electric dichroism and computer simulations. Hemoglobins from normal human cells, from sickle cells, and from horse were investigated by electrooptical methods in their oxy and deoxy forms. The reduced linear dichroism measured as a function of the electric field strength demonstrates the existence of permanent dipole moments in the range of 250-400 Debye units. The reduced limiting dichroism is relatively small (< or = 0.1); it is negative for hemoglobin from sickle cells and positive for the hemoglobins from normal human cells and from horse. The dichroism decay time constants are in the range from about 55 to 90 ns. Calculations of th...
[American Quarter Horses and HYPP]. Hyperkalaemic periodic paralysis is a genetic disease that affects the American Quarter Horse population and is caused by a mutation. As a result of this mutation in a gene which codes for the sodium channel in muscle cells, severe muscle weakness can appear. Reliable DNA-tests can establish whether a horse is homozygous negative, heterozygous, or homozygous positive for this mutation. Therapy and prevention are discussed.
The complete cDNA and deduced amino acid sequence of equine IgE. The cDNA from a transcript encoding the complete heavy chain of the equine immunoglobulin IgE has been cloned and sequenced. A fragment of the equine epsilon gene was amplified from cDNA using PCR and this fragment was then used to probe a horse cDNA library prepared from peripheral blood lymphocytes. A recombinant clone containing the cDNA encoding the complete horse epsilon chain and its associated V-D-J and leader, was subsequently isolated and sequenced. Comparison of the deduced amino acid sequence of equine IgE with the C epsilon heavy chains of other species indicates it to be most simi...
Genetic homogeneity of Taylorella equigenitalis from Norwegian trotting horses revealed by chromosomal DNA fingerprinting. Chromosomal DNA fingerprinting indicated that Norwegian Taylorella equigenitalis strains are genetically homogeneous and similar to some Swedish isolates but different from other European strains. As contagious equine metritis is rarely a serious disease in Norwegian horses, we conclude that the dominant T. equigenitalis strain in Norway is a genetically homogeneous clone of low virulence.
Molecular analysis of an XY mare with gonadal dysgenesis. In this study, cytogenetic analysis of an infertile mare revealed a 64, XY karyotype. The XY sex-reversed animal had a female phenotype with gonadal dysgenesis. Using Southern blot analysis, we tested for the presence of two Y-specific genes SRY and ZFY by using DNA isolated from peripheral blood leukocytes. The results showed that at least the DNA-binding domain of the SRY gene was deleted from the Y chromosome of the XY mare but that the ZFY gene was present on this chromosome.
Genotyping of isolates of Taylorella equigenitalis from thoroughbred brood mares in Japan. Profiles of the genomic DNA of 104 strains of T. equigenitalis isolated from brood mares with contagious equine metritis in Hokkaido during the breeding seasons from 1980 to 1993, as well as those of five strains (SS28, EQ56, EQ59, EQ70 and HH139) previously isolated in Japan were examined after restriction digestion and crossed-field gel electrophoresis. These profiles were essentially identical to each other and the various isolates and strains appeared to have a common genotype, designated 'genotype J', with respect to two restriction enzymes, ApaI and NotI. These results suggest a common s...
Dermatophytes and other keratinophilic fungi causing ringworm of horses. From 60 horses showing skin lesions, 42% were positive for fungal infection. Horses less than 2-year old were more susceptible to this infection. Fourteen species belonging to nine genera of keratinophilic and cycloheximide-resistant fungi were recovered from collected specimens. Trichophyton was the dominant genus of which T. equinum was the most common. This species proved to be the main causative agent of ringworm in horses. In addition to dermatophytes, many species of the isolated fungi were keratinophilic. The presence of such fungi on hairs and skin of horses may create an opportunity f...
Insulin-like growth factor II gene expression in the fetus and placenta of the horse during the first half of gestation. Placentation in equids involves two types of trophoblast: a minor invasive component, the chorionic girdle, that gives rise to transient endocrine structures known as endometrial cups, and a major non-invasive component, the allantochorion, that forms the diffuse, microcotyledonary placenta. Growth factors are likely to be important in controlling these complex events at implantation and this study describes the use of in situ hybridization and northern blotting techniques to monitor expression of insulin-like growth factor II (IGF-II) in the fetus and placenta of the horse (Equus caballus), u...
The nucleotide sequence of asinine herpesvirus 3 glycoprotein G indicates that the donkey virus is closely related to equine herpesvirus 1. The nucleotide sequence of the glycoprotein G (gG) homologue of asinine herpesvirus 3 (AHV3), a respiratory alphaherpesvirus of donkeys, was determined. The AHV3 gG gene consists of 1233 base pairs (bp) and codes for a predicted protein of 411 amino acids. This is identical in size to the equine herpesvirus 1 (EHV1) gG gene and 6 amino acids longer than the equine herpesvirus 4 (EHV4) gG gene. The predicted amino acid sequence of AHV3 gG has characteristics of a class 1 membrane protein. The amino acid sequence of AHV3 gG shows 92% and 60% identity to EHV1 gG and EHV4 gG respectively. Two regi...
Detection of equine arteritis virus (EAV) by polymerase chain reaction (PCR) and differentiation of EAV strains by restriction enzyme analysis of PCR products. A polymerase chain reaction (PCR) based assay capable of detecting and differentiating seven strains of equine arteritis virus (EAV) from around the world was developed. The primers for the PCR were chosen from the ORF6 gene encoding the unglycosylated membrane protein (M). Viral RNA from cell culture fluids infected with each of the seven EAV strains and RNA from the live vaccine, Arvac, was detected by PCR using four sets of primers. The sensitivity of detection was increased from 100 to 1,000 times by performing nested PCR enabling the detection of RNA at a level of 0.5-5 PFU. Differentiati...
