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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.
Isolation from the horse genome of a new DNA transposon belonging to the Tigger family. Tigger elements are human DNA transposons homologous to the pogo element of Drosophila melanogaster. They contain an open reading frame for a transposase very similar to the major mammalian centromere protein CENP-B. We found in the horse genome a DNA element ( Ecatig3) sharing 88% homology with human Tigger3. The presence of Tigger elements in the horse genome confirms previous data that date these elements before the divergence between Perissodactyla and Primates (80-90 Myr ago). Copy number evaluation indicates that the horse element is much more abundant than its human counterpart. Souther...
Absence of the functional Myosin heavy chain 2b isoform in equine skeletal muscles. Nucleotide sequences which included the full coding region for three types of myosin heavy chain (MyHC) isoforms were determined from equine skeletal muscles. The deduced amino acid sequences were 1937, 1938, and 1935 residues for the MyHC-2a, -2x, and -slow, respectively. No MyHC-2b isoform was amplified from the equine muscle cDNA except for one pseudogene fragment. One nucleotide was inserted in the coding region of the equine pseudogene product, a minute amount of which was expressed in the skeletal muscle. The 596 bp sequence of the equine MyHC pseudogene was categorized into the MyHC-2b ...
[Inguinal herniation in foals. Literature review and a case report]. A literature review is given concerning the occurrence, clinical signs and possible treatment of the different types of inguinal herniation in foals. A six-week old filly with a reducible inguinal hernia is described in detail.
Phage display of the Equine arteritis virus nsp1 ZF domain and examination of its metal interactions. A putative zinc finger (ZF) domain in the Equine arteritis virus (EAV) nsp1 protein was described recently to be required for viral transcription. The nsp1 ZF (50 aa) was expressed on the surface of M13KE gIII phage, fused to the N terminus of the phage pIII protein. To evaluate the functionality of the ZF domain, a binding assay was developed, based on the use of immobilized Ni(2+) ions (Ni-NTA). Phages displaying ZF bound significantly better to Ni-NTA than did phages displaying negative-control peptides, which also contained metal-coordinating residues. Also, binding of ZF-displaying phages...
Germ cell apoptosis in the testes of normal stallions. Apoptosis in testicular germ cells has been demonstrated in many mammalian species. However, little is known about the stallion (Equus caballus) and rates of apoptosis during spermatogenesis. Morphological and biochemical features of apoptosis reported in other species were used to confirm that the TdT-mediated dUTP Nick end labeling (TUNEL) assay is an acceptable method for identification and quantification of apoptotic germ cells in histological tissue sections from stallion testis. Seminiferous tubules from eight stallions with normal testis size and semen quality were evaluated according t...
Chronic equine laminitis is characterised by loss of GLUT1, GLUT4 and ENaC positive laminar keratinocytes. Equine laminitis is a multifactorial connective tissue disorder with major implications for the welfare of horses. There are few published studies on phenotypic markers for identification of equine laminar keratinocytes using immunohistochemical techniques. Objective: To establish whether the epithelial sodium channel (ENaC) and the GLUT1 and GLUT4 facilitative glucose transporters may be used as phenotypic markers for identification of equine laminar keratinocytes using immunohistochemical techniques to monitor changes in the keratinocyte population in laminitis. Methods: Histology and immuno...
Expression of constitutive endothelial, neuronal and inducible nitric oxide synthase in the testis and epididymis of horse. The expression of three isoforms of nitric oxide synthase (NOS) were examined in the testis and epididymis of a thoroughbred horse. Immunohistochemical studies demonstrated the presence of eNOS immunostaining in some germ cells in the seminiferous tubules and in vascular endothelial cells in the interstitial tissues. Interstitial cells, most likely Leydig cells, were also intensely immunopositive for eNOS. The pattern of immunostaining for nNOS was similar to that for eNOS in the testis. Weak expression of iNOS was detected in the seminiferous tubules of the testis, but intense expression was ...
Equine beta-defensin-1: full-length cDNA sequence and tissue expression. beta-Defensins are cysteine-rich endogenously produced antimicrobial peptides that play an important role in innate immune defense. Although, previous investigations have identified beta-defensins in several mammalian species, no reports have identified equine beta-defensins. Using a strategy of database searching for expressed sequence tags (EST) we identified putative expression of equine beta-defensins in hepatic tissue. Based on this information, sequence specific primers were designed for the equine gene enabling the identification of the full-length cDNA sequence of equine beta-defensin-...
Review of horses in Paleoindian sites of the Americas. Analysis of the morphological characters in North and South American horses present during Paleoindian time indicates that at least eight Equus ecospecies occurred in North America. In South America, Equus had radiated into four ecospecies, Hippidion had one, and Onohippidium had three geographically separate ecospecies. These species are found in archeological deposits ranging from ca. 13,000 to 8,000 yr B.P., in tropical habitats as well as in the high Andean and Patagonian colder ecotopes.
Equine catechol estrogen 4-hydroxyequilenin is a more potent inhibitor of the variant form of catechol-O-methyltransferase. Catechol-O-methyltransferase (COMT) plays an important role in the inactivation of biologically active and toxic catechols. It has been shown that COMT is genetically polymorphic with a wild-type and variant form where a valine has been substituted with a methionine. Several, but not all, epidemiological studies have shown that women, homozygous with the variant form, have an increased risk of developing breast cancer. Previously, we showed that 4-hydroxyequilenin (4-OHEN), a cytotoxic/genotoxic equine catechol estrogen metabolite, is both a substrate of COMT and an irreversible inhibitor of t...
Polymerase chain reaction tests for the identification of Ross River, Kunjin and Murray Valley encephalitis virus infections in horses. To develop and validate specific, sensitive and rapid diagnostic tests using RT-PCR for the detection of Ross River virus (RRV), Kunjin virus (KV) and Murray Valley encephalitis virus (MVEV) infections in horses. Methods: Primer sets based on nucleotide sequence encoding the envelope glycoprotein E2 of RRV and on the nonstructural protein 5 (NS5) of KV and MVEV were designed and used in single round PCRs to test for the respective viruses in infected cell cultures and, in the case of RRV, in samples of horse blood and synovial fluid. Results: The primer pairs designed for each of the three vir...
Effect of inbreeding on the incidence of retained placenta in Friesian horses. This study was motivated by the hypothesis that the incidence of retained placenta (RP) in Friesian horses is associated with inbreeding. The objectives were to 1) calculate the inbreeding rate in the total registered Friesian horse population; 2) study the association of the inbreeding coefficient of the foal and the mare with the incidence of RP; and 3) study the heritability of RP in Friesian mares after normal foalings. Data from the total registered Friesian horse population from 1879 to 2000 (52,392 individuals) were collected from the registration files of the Friesian Horse Studbook. I...
Modification of standard freezing media to limit capacitation and maximise motility of frozen-thawed equine spermatozoa. To investigate cryopreservation-induced capacitation-like changes in equine spermatozoa frozen in three different media using chlortetracycline (CTC) fluorescence staining analysis. Methods: Semen collected from three stallions was diluted in one of three centrifugation media and, after centrifugation and removal of supernatant, extended in corresponding freezing media containing additional egg yolk, glycerol, lactose and Equex paste. The semen was frozen in 5 mL straws and the spermatozoa assessed for motility and membrane quality after thawing. Results: Following centrifugation, spermatozoa ...
Growth rate consists of baseline and systematic deviation components in Thoroughbreds. The objective of this study was to establish a procedure for differentiating a baseline curve from a systematic deviation in weight-age data, and hence to develop a physiological growth model for the Thoroughbred. A total of 2,698 records for 175 foals was obtained during a period of 8 yr (1994 to 2001). Weight-age data were fit with a sigmoid growth equation, W = A(1 + be(-kt))M, where W is BW at age t, A is the asymptotic value of W, b is a scaling parameter that defines the degree of maturity at t = 0, k is a rate constant, and M defines the point of inflection in the sigmoid curve in relat...
Isolation of Y chromosome-specific microsatellites in the horse and cross-species amplification in the genus Equus. Y chromosome polymorphisms such as microsatellites or single nucleotide polymorphisms represent a paternal counterpart to mitochondrial DNA (mtDNA) for evolutionary and phylogeographic studies. The use of Y chromosome haplotyping in natural populations of species other than humans is still hindered by the lack of sequence information necessary for polymorphism screening. Here we used representational difference analysis (RDA) followed by a screen of a bacterial artificial chromosome (BAC) library for repetitive sequences to obtain polymorphic Y-chromosomal markers. The procedure was performed ...
[Genealogic analysis of hereditary components of a metapopulation of Przhevalsky horse]. The current condition of the megapopulation of the Przhevalsky horse was assessed using genetic indices of biological diversity of species and genealogical analysis and taking into account both nuclear and non-nuclear (mitochondrial), maternally inherited components of hereditary information.
Cumulus-oocyte communications in the horse: role of the breeding season and of the maturation medium. Horse is a seasonal breeder and information on oocyte quality outside the breeding season is very limited. Ovaries obtained at the slaughterhouse are a convenient but often limited source of oocytes in this species. As the low quantity of ovaries leads to an intensive use of all available material, it would be useful to know whether ovaries collected during the non-breeding season are suitable for in vitro maturation (IVM). In an attempt to characterize the effect of season on oocyte quality, we investigated the permeability of the gap junctions (GJ) present between cumulus cells and oocytes b...
Frequency and distribution of tetracycline resistance genes in genetically diverse, nonselected, and nonclinical Escherichia coli strains isolated from diverse human and animal sources. Nonselected and natural populations of Escherichia coli from 12 animal sources and humans were examined for the presence and types of 14 tetracycline resistance determinants. Of 1,263 unique E. coli isolates from humans, pigs, chickens, turkeys, sheep, cows, goats, cats, dogs, horses, geese, ducks, and deer, 31% were highly resistant to tetracycline. More than 78, 47, and 41% of the E. coli isolates from pigs, chickens, and turkeys were resistant or highly resistant to tetracycline, respectively. Tetracycline MICs for 61, 29, and 29% of E. coli isolates from pig, chickens, and turkeys, respect...
Cloning and comparative analysis of the bovine, porcine, and equine sex chromosome genes ZFX and ZFY. A growing body of evidence suggests the involvement of sex chromosome genes in mammalian development. We report the cloning and characterization of the complete coding regions of the bovine Y chromosome ZFY and X chromosome ZFX genes, and partial coding regions of porcine and equine ZFX and ZFY genes. Bovine ZFY and ZFX are highly similar to each other and to ZFX and ZFY from other species. While bovine and human ZFY proteins are both 801 amino acids long, bovine ZFX is 5 amino acids shorter than human ZFX. Like in humans, both bovine ZFY and ZFX contain 13 zinc finger motifs and belong to the...
Factors affecting developmental competence of equine oocytes after intracytoplasmic sperm injection. This study was conducted to evaluate the effect of initial cumulus morphology (expanded or compact) and duration of in vitro maturation (24, 30 or 42 h) on the developmental competence of equine oocytes after intracytoplasmic sperm injection (ICSI). The effect of manipulation temperature (room temperature vs 37 degrees C) at the time of ICSI and concentration of glucose (0.55 vs 5.5 mM) during embryo culture was also investigated. The nuclear maturation rates of expanded (Ex) oocytes were significantly (P < 0.001) higher than those of compact (Cp) oocytes at all maturation times (61-72 vs 23-2...
The influence of maternal size on pre- and postnatal growth in the horse: III Postnatal growth. The growth parameters exhibited by seven Thoroughbred (Tb) foals that had experienced a 'restricted' in utero existence following transfer as embryos to the uteri of smaller Pony (P) mares (Tb-in-P) and, conversely, six P foals that experienced a 'luxurious' in utero existence after transfer to larger Tb mares (P-in-Tb), were compared from birth to 3 years of age with those exhibited by six normal Tb-in-Tb and six P-in-P foals conceived by within-breed artificial insemination. Bodyweight, height at the withers, girth, poll-to-nose length, crown-rump length and three foreleg longbone measuremen...
Placental teratocarcinoma in a mare with possible metastasis to the foal. A teratocarcinoma was diagnosed in the amnion of a 5-year-old Arabian mare that delivered a healthy, full-term foal. The foal died at 2.5 months of age as a result of metastasis of an undifferentiated component of the mass. This case is unique because it is the first reported case of placental teratocarcinoma in animals and the malignant component apparently metastasized to the foal resulting in its death.
Characterization of the neutralization determinants of equine arteritis virus using recombinant chimeric viruses and site-specific mutagenesis of an infectious cDNA clone. We have used an infectious cDNA clone of equine arteritis virus (EAV) and reverse genetics technology to further characterize the neutralization determinants in the GP5 envelope glycoprotein of the virus. We generated a panel of 20 recombinant viruses, including 10 chimeric viruses that each contained the ORF5 (which encodes GP5) of different laboratory, field, and vaccine strains of EAV, a chimeric virus containing the N-terminal ectodomain of GP5 of a European strain of porcine reproductive and respiratory syndrome virus, and 9 mutant viruses with site-specific substitutions in their GP5 pro...
[Analysis of the prevalence of pastern dermatitis in German Coldblood horse breeds]. The prevalence of pastern dermatitis was investigated in 917 German Coldblood horses aged 2.5 to 26 years. Pastern dermatitis was prevalent in Black Forest Draught horses with 47.5% and in South German Draught horses with 58.5%. High prevalences were found in Mecklenburg (76.4%), Saxon-Thuringa (84.3%), Schleswig (86.0%), and Rhenisch German Coldblood (96.1%) horses. All four legs or both hind legs were affected most frequently. The most prevalent forms of pastern dermatitis were crusted and hyperkeratotic-hyperplastic. The occurrence of pastern dermatitis was dependent of age. The statistical...
Streptococcus devriesei sp. nov., from equine teeth. Phenotypic and phylogenetic studies were performed on four unidentified Gram-positive staining, catalase-negative, alpha-hemolytic Streptococcus-like organisms recovered from the teeth of horses. SDS PAGE analysis of whole-cell proteins and comparative 16S rRNA gene sequencing demonstrated the four strains were highly related to each other but that they did not correspond to any recognised species of the genus Streptococcus. Phylogenetic analysis based on 16S rRNA gene sequences showed the unidentified organisms form a hitherto unknown sub-line within the Streptococcus genus, displaying a clos...
