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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.
Characterisation of Australian isolates of Actinobacillus capsulatus, Actinobacillus equuli, Pasteurella caballi and Bisgaard Taxa 9 and 11. The objective of this work was to perform a comprehensive phenotypic characterisation of 16 isolates of bacteria previously identified as Actinobacillus equuli. Methods: The 16 isolates that had been obtained from Australian animals--15 from horses and one from a rabbit--were compared with reference strains of A equuli, A capsulatus, Pasteurella caballi and Bisgaard Taxa 9 and 11. Results: The characterisation study demonstrated that only nine of the isolates were A equuli. The other isolates were identified as A capsulatus (the isolate from rabbit), P caballi (one isolate), Bisgaard Taxon 11 ...
[The spontaneous reduction of a twin pregnancy in two mares]. Twin pregnancies are a serious problem in stud medicine as they terminate in most cases in abortion, stillbirth or the delivery of dead or weak and deformed foals. In recent years, the introduction of sonography has greatly improved the management of mares with twin conceptuses, in particular monitoring the phenomenon of spontaneous embryo reduction to a single vesicle. This allows supervision of pregnancy with relatively little expenditure and loss of time. We document the spontaneous reduction to single vesicles of unilateral twin pregnancies in a draught- and a warmblood-mare. In both mares...
Characterization of horse (Equus caballus) immunoglobulin mu chain-encoding genes. Horse (Equus caballus) immunoglobulin mu chain-encoding (IgM) variable, joining, and constant gene segments were cloned and characterized. Nucleotide sequence analyses of 15 cDNA clones from a mesenteric lymph node library identified 7 unique variable gene segments, 5 separate joining segments, and a single constant region. Based on comparison with human sequences, horse variable segments could be grouped into either family 1 of immunoglobulin (Ig) clan I or family 4 of Ig clan II subclan IV. All horse sequences had a relatively conserved 16 base pair (bp) segment in framework 3 which was reco...
Identification, cloning and sequence analysis of the equine adenovirus 1 hexon gene. Based on sequence homology with human adenovirus 2 (HAdV2), the hexon gene of equine adenovirus 1 (EAdV1) was identified. HindIII restriction fragments containing the hexon and other viral genes were cloned into the plasmids pUC19 and pBlueScript SK(-) and sequenced. The nucleotide sequence of the hexon gene was completely determined and partial sequence data were obtained for seven other EAdV1 genes. Amino acid (aa) sequence comparison with published adenovirus (AdV) proteins identified the genes for the IIIa, penton, pVII, PVI, 23K proteinase, DNA binding and 100K proteins. The eight EAdV1 g...
Adaptation of equine herpesvirus 1 to unnatural host led to mutation of the gC resulting in increased susceptibility of the virus to heparin. Heparin extensively inhibited infection of MDBK cells by equine herpesvirus 1 (EHV-1) strains adapted to bovine cells or hamsters, while the reagent merely reduced infectivity of strains passaged only in equine cells. The gC of two strains adapted to non-equine cells seemed to have higher affinity for heparin, although the reagent bound to both the gC and gB of all strains tested. Amino acid substitutions of the gC of the EHV-1 strains adapted to non-equine cells converged on the hydrophilic regions, amino acid residues 92 to 175, resulting in the glycoprotein becoming more cationic. These res...
Local electrostatic potentials in pyridoxal phosphate labelled horse heart cytochrome c. The present work shows the application of an optical label pyridoxal phosphate (PLP) for the experimental determination of local electrostatic potentials in singly substituted cytochromes c modified by pyridoxal phosphate at Lys 79 (PLP-Lys-79-cyt.c) or at Lys 86 (PLP-Lys-86-cyt.c). PLP has also been used to calculate the pKa values of all ionizable groups and the electrostatic potentials in the modified proteins and to analyse their properties. The experimental pKa values for the pyridine nitrogen and phenolic hydroxyl of the bound label were obtained from pH-dependent absorbance and fluoresc...
Mutational changes in the hemagglutinin of equine H3 influenza viruses result in the introduction of a glycosylation site which enhances the infectivity of the viruses. The complete amino acid sequences of the hemagglutinin (HA) glycoprotein of three equine-2 influenza viruses from tropical Africa are presented in comparison with that of a well characterized European equine-2 virus (Suffolk/89) and a consensus sequence from the database. The sequences of the tropical African viruses were deduced from the complete nucleotide sequences of their HA genes reported earlier. Mutational changes in the nucleotide sequences resulted in amino acid changes in the HA which led to the introduction of a new asparagine-linked (N-linked) glycosylation site in two viruses. Th...
Directional and anteroposterior asymmetry of common white markings in the legs of the Arabian horse: response to selection. Arabian bay horses manifest, on the average, more common white markings in their hind legs than their forelegs (anteroposterior asymmetry) and more common white markings in their left legs than their right legs (directional asymmetry). To determine if genetic variation exists for these types of asymmetry, the phenotypic response was studied in bay foals when their dams and sires were selected for the directions of fore-hind and left-right differences. In the fore-hind studies, the quantitative shifts in the bay foals were in the direction specified by the selection scheme and the observed devi...
cDNA cloning and sequencing reveal the major horse allergen Equ c1 to be a glycoprotein member of the lipocalin superfamily. The gene encoding the major horse allergen, designated Equus caballus allergen 1 (Equ c1), was cloned from total cDNA of sublingual salivary glands by reverse transcription-polymerase chain reaction using synthetic degenerate oligonucleotides deduced from N-terminal and internal peptide sequences of the glycosylated hair dandruff protein. A recombinant form of the protein, with a polyhistidine tail, was expressed in Escherichia coli and purified by immobilized metal affinity chromatography. The recombinant protein is able to induce a passive cutaneous anaphylaxis reaction in rat, and it behave...
Structural features of mammalian gonadotropins. There are two species for which both pituitary and placental gonadotropins are readily available, humans and horses. The human gonadotropins are better characterized than equine gonadotropins. Nevertheless, the latter are very interesting because they provide exceptions to some of the general structure-function principles derived from studies on human and other mammalian gonadotropins. For example, separate genes encode the hLH beta and hCG beta subunits while a single gene encodes eLH beta and eCG beta. Thus, eCG and eLH differ only in their oligosaccharide moieties and eLH is the only LH tha...
Primary structure of stallion seminal plasma protein HSP-7, a zona-pellucida-binding protein of the spermadhesin family. The primary-structure of HSP-7, a 14-kDa protein isolated from stallion seminal plasma, has been determined, HSP-7 belongs to the spermadhesin protein family, shares 98% sequence identity with the boar seminal plasma protein AWN, and, like its boar homolog, displays zona-pellucida-binding activity. Despite these conserved structural and functional features, the equine and porcine spermadhesins differ in their topography on spermatozoa.
The equine periodic paralysis Na+ channel mutation alters molecular transitions between the open and inactivated states. 1. The Na+ channel mutation associated with equine hyperkalaemic periodic paralysis (HPP) affects a highly conserved phenylalanine residue in an unexplored region of the alpha-subunit. This mutation was introduced into the rat skeletal muscle Na+ channel gene at the corresponding location (i.e. F1412L) for functional expression and characterization in Xenopus oocytes. 2. In comparison with wild-type (WT) channels, equine HPP channels showed clear evidence for disruption of inactivation: increased time-to-peak current, slowed rates of whole-cell current decay, significant increases in sustained...
A missense mutation in the gene for melanocyte-stimulating hormone receptor (MC1R) is associated with the chestnut coat color in horses. The melanocyte-stimulating hormone receptor gene (MC1R) is the major candidate gene for the chestnut coat color in horses since it is assumed to be controlled by an allele at the extension locus. MC1R sequences were PCR amplified from chestnut (e/e) and non-chestnut (E/-) horses. A single-strand conformation polymorphism was found that showed a complete association to the chestnut coat color among 144 horses representing 12 breeds. Sequence analysis revealed a single missense mutation (83Ser-->Phe) in the MC1R allele associated with the chestnut color. The substitution occurs in the second ...
A 19 kDa protein secreted by the endometrium of the mare is a novel member of the lipocalin family. Large quantities of an unusual 19 kDa protein (p19) are secreted into the lumen of the uterus of the mare (Equus caballus) during the oestrous cycle and early pregnancy. p19 associates strongly with the acellular capsule that surrounds the young horse conceptus and is believed to be important in maintaining pregnancy. Here we report the complete cDNA sequence encoding p19, its expression patterns in horse tissues and a Southern blot analysis of the gene in horse DNA. The predicted amino acid sequence of the p19 cDNA demonstrated a signal peptide of 18 residues and a mature protein of 162 resid...
Analysis of the long terminal repeat from a cytopathic strain of equine infectious anemia virus. Sequential passage of the tissue culture-adapted prototype strain of EIAV in fetal donkey dermal (FDD) cell cultures generated a virus stock which exhibits cytopathic effects in FDD cell cultures. In this study, the effects of the long terminal repeat (LTR) region on virus replication and cytopathogenicity were examined. The FDD-adapted virus LTR was found to contain a number of base pair mutations and a large insertion within the U3 region in comparison with the previously characterized LTR, lambda12. Transient gene expression studies showed that basal promoter activity, in FDD cell cultures,...
Linear assessment of the thoroughbred horse: an approach to conformation evaluation. A linear assessment trait evaluation system is proposed to allow quantitative description of the static conformation of the horse. Measurements were made on 27 selected traits. The system was tested initially for repeatability of measurements on 4 horses. Twenty-one of the selected traits were satisfactory and 6 proved unsatisfactory in terms of reproducibility. A population of 101, superior 2- and 3-year-old Thoroughbreds and 19 premium Thoroughbred stallions were similarly assessed. More than 65% of the traits exhibited large (CV > 10%) phenotypic variation within the sampled population. ...
Scanning electron microscopy of the equine oviduct and observations on ciliary currents in vitro at day 2 after ovulation. There are considerable differences between mammalian species in the distribution and activity of ciliated cells within the oviduct, and limited information is available concerning either the distribution or activity of cilia within the equine oviduct. Patterns of ciliary activity were characterized in the ampulla and isthmus of oviducts recovered at 2 d after ovulation from 10 mares, and scanning electron microscopy was used to examine regional differences in the distribution of cilia in oviducts from 3 of these mares. Based upon the motility of 15 microm latex microspheres, ciliary activity w...
A study (1977-1992) of population dynamics of endoparasites featuring benzimidazole-resistant small strongyles (population S) in Shetland ponies. Critical tests (91) were done between 1977 and 1992 in Shetland ponies to evaluate drug susceptibility and population dynamics (present paper) of endoparasites. The test ponies, most less than 1 year old, were from a herd where older animals were treated every 8 weeks initially with cambendazole (CBZ) (1974-1978) and then with oxibendazole (OBZ) (1978-1992). Previous field test data (1974-1992) on older ponies in the breeding herd indicated the presence of benzimidazole (BZ) resistant small strongyles. Data on population dynamics from the present critical tests indicated that 28 species of sma...
Use of peanut agglutinin to assess the acrosomal status and the zona pellucida-induced acrosome reaction in stallion spermatozoa. Peanut agglutinin (PNA) was used to assess the sperm acrosomal status and the acrosome reaction during gamete interaction in the equine species. PNA exclusively binds to the outer acrosomal membrane of stallion spermatozoa, as was established by transmission electron microscopy. Fluorescein isothiocyanate-PNA (FITC-PNA) labeling was used to monitor sperm acrosomal changes during a prolonged incubation period of 24 hours and during a 2-hours incubation in the presence of 5 microM calcium ionophore A23187. In addition, after a 4-hours preincubation in SP-TALP medium, sperm samples were incubated...
Expression of Vitreoscilla hemoglobin is superior to horse heart myoglobin or yeast flavohemoglobin expression for enhancing Escherichia coli growth in a microaerobic bioreactor. Expression of a gene encoding hemoglobin (VHb) from the aerobic bacterium Vitreoscilla sp. in several organisms, including Escherichia coli, has been shown to improve microaerobic cell growth and enhance oxygen-dependent product formation. The suitability of VHb to enhance microaerobic metabolism has been suggested to depend on its unusual oxygen binding characteristics. To examine whether hemoproteins of other origins can also elicit the positive effects VHb exerts in microaerobic E. coli cells, we subcloned the genes encoding Vitreoscilla VHb, horse heart myoglobin (HMb), and yeast flavohemo...
The complete mitochondrial DNA (mtDNA) of the donkey and mtDNA comparisons among four closely related mammalian species-pairs. The nucleotide sequence of the complete mitochondrial genome of the donkey, Equus asinus, was determined. The length of the molecule is 16,670 bp. The length, however, is not absolute due to pronounced heteroplasmy caused by variable numbers of two types of repetitive motifs in the control region. The sequence of the repeats is (a) 5'-CACACCCA and (b) 5'-TGCGCGCA, respectively. The order of (a) and (b) can be expressed as {n[2(a)+(b)]+m(a)}. In 32 different clones analyzed the number of n and m ranged from 0 to 9 and 1 to 7. The two rRNA genes, the 13 peptide-coding genes, and the 22 tRNA gene...
Equine motor neuron disease is not linked to Cu/Zn superoxide dismutase mutations: sequence analysis of the equine Cu/Zn superoxide dismutase cDNA. The cDNA encoding the equine copper/zinc superoxide dismutase (SOD1) was cloned from leukocyte total RNA from healthy horses and its nucleotide (nt) sequence was determined. We further sequenced the SOD1 gene from 16 horses diagnosed with equine motor neuron disease (EMND) and eight unrelated, clinically normal horses to determine if this disease, similar to amyotrophic lateral sclerosis (ALS) in humans, is linked to SOD1 mutations. The 465-bp SOD1 coding region in the horse encodes 153 amino acid (aa) residues. Equine SOD1 exhibited 81.8 and 79.9% sequence identity to the human homolog at the...
Identification of an alternatively spliced transcript of equine interleukin-1 beta. Using lipopolysaccharide (LPS)-stimulated equine peripheral blood mononuclear cell (PBMC) cDNA as a template, we performed polymerase chain reaction (PCR) amplification with equine interleukin-1 beta (IL-1 beta) specific primers. Electrophoresis of the PCR product on agarose gel revealed an additional smaller fragment that hybridized with an equine IL-1 beta cDNA probe. Sequencing of this fragment demonstrated that it was shorter than normal equine IL-1 beta cDNA by 162 nucleotides, which corresponded to exon 5 of the human and murine IL-1 beta genes. The deletion of 162 nucleotides did not re...
