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Topic:Chromosomes
Chromosomes in horses are structures composed of DNA and proteins that carry genetic information crucial for the development, functioning, and reproduction of equine species. Horses typically have 64 chromosomes, organized into 32 pairs, which include one pair of sex chromosomes that determine the genetic sex of the individual. Chromosomal analysis in horses is used to study genetic disorders, inheritance patterns, and species evolution. Variations or abnormalities in chromosome number or structure can lead to developmental issues and impact fertility. This page compiles peer-reviewed research studies and scholarly articles that explore the structure, function, and implications of chromosomal variations in equine genetics and breeding.
Three autosomal chromosome translocations associated with repeated early embryonic loss (REEL) in the domestic horse (Equus caballus). Repeated early embryonic loss (REEL) represents a considerable economic loss to the horse industry. Mares that experience REEL may be overlooked as potential carriers of a chromosome abnormality. Here we report three different autosomal translocations in Thoroughbred mares presented for chromosome analysis because of REEL. The karyotypes were 64,XX,t(1;21), 64,XX,t(16;22), and 64,XX,t(4;13), respectively. In order to confirm the chromosomes involved in the translocations, to map the breakpoints, and to determine if the translocations were reciprocal, genes surrounding the breakpoints were iden...
An equine chromosome 3 inversion is associated with the tobiano spotting pattern in German horse breeds. The tobiano white-spotting pattern is one of several known depigmentation phenotypes in horses and is desired by many horse breeders and owners. The tobiano spotting phenotype is inherited as an autosomal dominant trait. Horses that are heterozygous or homozygous for the tobiano allele (To) are phenotypically indistinguishable. A SNP associated with To had previously been identified in intron 13 of the equine KIT gene and was used for an indirect gene test. The test was useful in several horse breeds. However, genotyping this sequence variant in the Lewitzer horse breed revealed that 14% of ho...
Application of primed in situ DNA synthesis (PRINS) with telomere human commercial kit in molecular cytogenetics of Equus caballus and Sus scrofa scrofa. Recently, molecular techniques have become an indispensable tools for cytogenetic research. Especially, development of in situ techniques made possible detection at the chromosomal level, genes as well as repetitive sequences like telomeres or the DNA component of telomeres. One of these methods is primed in situ DNA synthesis (PRINS) using an oligonucleotide primer complementary to the specific DNA sequence. In this report we described application of PRINS technique with telomere human commercial kit to telomere sequences identification. This commercial kit may be use to visualization of inte...
Multidirectional cross-species painting illuminates the history of karyotypic evolution in Perissodactyla. The order Perissodactyla, the group of odd-toed ungulates, includes three extant families: Equidae, Tapiridae, and Rhinocerotidae. The extremely rapid karyotypic diversification in perissodactyls has so far prevented the establishment of genome-wide homology maps between these three families by traditional cytogenetic approaches. Here we report the first genome-wide comparative chromosome maps of African rhinoceroses, four tapir species, four equine species, and humans. These maps were established by multidirectional chromosome painting, with paint probes derived from flow-sorted chromosomes o...
Genetic analysis of white facial and leg markings in the Swiss Franches-Montagnes Horse Breed. White markings and spotting patterns in animal species are thought to be a result of the domestication process. They often serve for the identification of individuals but sometimes are accompanied by complex pathological syndromes. In the Swiss Franches-Montagnes horse population, white markings increased vastly in size and occurrence during the past 30 years, although the breeding goal demands a horse with as little depigmented areas as possible. In order to improve selection and avoid more excessive depigmentation on the population level, we estimated population parameters and breeding value...
The horse genome derby: racing from map to whole genome sequence. The map of the horse genome has undergone unprecedented expansion during the past six years. Beginning from a modest collection of approximately 300 mapped markers scattered on the 31 pairs of autosomes and the X chromosome in 2001, today the horse genome is among the best-mapped in domestic animals. Presently, high-resolution linearly ordered gene maps are available for all autosomes as well as the X and the Y chromosome. The approximately 4350 mapped markers distributed over the approximately 2.68 Gbp long equine genome provide on average 1 marker every 620 kb. Among the most remarkable deve...
A chromosome inversion near the KIT gene and the Tobiano spotting pattern in horses. Tobiano is a white spotting pattern in horses caused by a dominant gene, Tobiano(TO). Here, we report TO associated with a large paracentric chromosome inversion on horse chromosome 3. DNA sequences flanking the inversion were identified and a PCR test was developed to detect the inversion. The inversion was only found in horses with the tobiano pattern, including horses with diverse genetic backgrounds, which indicated a common genetic origin thousands of years ago. The inversion does not interrupt any annotated genes, but begins approximately 100 kb downstream of the KIT gene. This inversion...
Associations between candidate gene markers at a quantitative trait locus on equine chromosome 4 responsible for osteochondrosis dissecans in fetlock joints of South German Coldblood horses. A previously accomplished whole-genome scan for osteochondrosis (OC) and OC dissecans (OCD) in South German Coldblood horses using 250 microsatellite markers identified putative quantitative trait loci (QTL). A chromosome-wide significant QTL for fetlock OCD was found on Equus caballus chromosome (ECA) 4q at a relative position of 70.0-73.3 cM. The aim of this study was to analyze associations of single nucleotide polymorphisms (SNPs) in candidate genes for OC in this region. The association analysis included 32 affected and 64 unaffected horses. Three SNPs located in intron 8, intron 9, and 3...
The RSPO genes: chromosomal assignment in horse by FISH. This research aims to pinpoint the chromosomal location of R-spondin (RSPO) genes in horses. The R-spondin genes are known to be critical in vertebrate development, with mutations leading to significant [...]
Molecular characterization and chromosomal assignment of equine cartilage derived retinoic acid sensitive protein (CD-RAP)/melanoma inhibitory activity (MIA). Cartilage-derived retinoic acid sensitive protein (CD-RAP) also known as melanoma inhibitory activity (MIA) has already been established as a marker for chondrocyte differentiation and a number of cancerous conditions in humans. Studies have also shown that CD-RAP/MIA is a potential marker of joint disease. The objective of this study was to characterize the equine CD-RAP/MIA gene and thus make it available as a marker in cartilage research and clinical studies. Gene analysis revealed that the equine gene (GenBank accession no. EF679787) consists of four exons and three introns, and the homolo...
Genome-wide search for markers associated with osteochondrosis in Hanoverian warmblood horses. A genome-wide scan was performed to detect quantitative trait loci (QTLs) for osteochondrosis (OC) and osteochondrosis dissecans (OCD) in horses. The marker set comprised 260 microsatellites. We collected data from 211 Hanoverian warmblood horses consisting of 14 paternal half-sib families. Traits used were OC (fetlock and/or hock joints affected), OCD (fetlock and/or hock joints affected), fetlock OC, fetlock OCD, hock OC, and hock OCD. The first genome scan included 172 microsatellite markers. In a second step 88 additional markers were chosen to refine putative QTLs found in the first scan....
Application of arm-specific painting probes of horse X chromosome for karyotype analysis in an infertile Hutsul mare with 64,XX/65,XX+Xp karyotype: case report. A 5-year-old infertile Hutsul mare was subjected to cytogenetic analysis. Fluorescence in situ hybridisation (FISH) using the equine Xp and Xq chromosome painting probes was carried out on chromosome preparations obtained after blood lymphocyte culture. These probes were generated by chromosome microdissection and a large number of spreads was analysed (525). The karyotype formula of the analysed mare was 64,XX/65,XX+Xp with the ratio of the two lines being 99.4 and 0.6, respectively. The goal of the study was to apply chromosome microdissection and the FISH technique for cytogenetic diagnosti...
Karyotypic relationships among Equus grevyi, Equus burchelli and domestic horse defined using horse chromosome arm-specific probes. Using laser microdissection we prepared a set of horse chromosome arm-specific probes. Most of the probes were generated from horse chromosomes, some of them were derived from Equus zebra hartmannae. The set of probes were hybridized onto E. grevyi chromosomes in order to establish a genome-wide chromosomal correspondence between this zebra and horse. The use of arm-specific probes provided us with more information on the mutual arrangement of the genomes than we could obtain by means of whole-chromosome paints generated by flow sorting, even if we used reciprocal painting with probe sets from...
Chromosomal assignment of five equine genes responsible for the development of the skeletal and nervous systems. The research article focuses on identifying the locations of five horse genes related to the development of the skeletal and nervous systems. Sequence Analysis and Bacterial Artificial Chromosome (BAC) Library [...]
Karyotype evaluation among young horse populations in Poland. Five hundred young horses of the following breeds: Thoroughbred, Silesian, Malopolska, Wielkopolska, Polish Konik, Hutsul, Shetland Pony, Half-bred Anglo-Arabian, Noble Half-bred, Fjord and crosses were cytogenetically investigated. Chromosome preparations obtained after lymphocyte culture were analysed using conventional Giemsa staining and CBG-banding methods. In the case of abnormalities GTG-banding as well as FISH technique were applied. In ten mares different karyotypic abnormalities were diagnosed. One mare showed chromosome chimerism (64,XX/64,XY), eight had sex chromosomal aneuploidy (...
Mapping quantitative trait loci for osteochondrosis in fetlock and hock joints and palmar/plantar osseus fragments in fetlock joints of South German Coldblood horses. The aim of this study was to identify quantitative trait loci (QTL) for osteochondrosis (OC) and palmar/plantar osseous fragments (POF) in fetlock joints in a whole-genome scan of 219 South German Coldblood horses. Symptoms of OC and POF were checked by radiography in 117 South German Coldblood horses at a mean age of 17 months. The radiographic examination comprised the fetlock and hock joints of all limbs. The genome scan included 157 polymorphic microsatellite markers. All microsatellite markers were equally spaced over the 31 autosomes and the X chromosome, with an average distance of 17.7...
Fluorescent in situ hybridization mapping of the epidermal growth factor receptor gene in donkey. The physical localization of the epidermal growth factor receptor (EGFR) gene was performed on donkey chromosomes. Bacterial artificial chromosome DNA containing the equine EGFR gene was used to map this gene by fluorescent in situ hybridization on donkey metaphase chromosomes. The gene was mapped on donkey 1q21.1 region.
The mechanisms determining the nucleolar-organizing regions inactivation of domestic horse chromosomes. Cytogenetic investigations of the nucleolar-organizing regions (NORs) show that there is variation in the transcriptional activity of rDNA in many organisms. As a consequence, genetic polymorphism of these regions has been detected. The aim of the present study was to evaluate the hypothetic genetic mechanisms determining the NORs polymorphism of the domestic horse chromosomes. Molecular cytogenetic analyses were carried out on Hucul horses and the following techniques were used: fluorescence in situ hybridization (FISH), telomere primed in situ synthesis (PRINS), in situ nick-translation with...
A region on equine chromosome 13 is linked to recurrent airway obstruction in horses. REASONS FOR STUDY: Equine recurrent airway obstruction (RAO) is probably dependent on a complex interaction of genetic and environmental factors and shares many characteristic features with human asthma. Interleukin 4 receptor a chain (IL4RA) is a candidate gene because of its role in the development of human asthma, confirmation of this association is therefore required. Methods: The equine BAC clone containing the IL4RA gene was localised to ECA13q13 by the FISH method. Microsatellite markers in this region were investigated for possible association and linkage with RAO in 2 large Warmblood ...
Molecular genetic analysis of the ATP2A2 gene as candidate for chronic pastern dermatitis in German draft horses. Chronic pastern dermatitis predominantly affects draft horses, and this condition is characterized by hyperkeratotic-hyperplastic dermal alterations. Chronic pastern dermatitis resembles the acral-hemorrhagic phenotype of Darier-White disease in humans. The ATP2A2 gene has been shown to be responsible for human Darier-White. Thus, we chose ATP2A2 on equine chromosome 8 (ECA8) as candidate for chronic pastern dermatitis in coldblood horses. A linkage analysis was performed in 10 paternal half-sib families consisting of 85 German coldblood horses using a microsatellite closely linked to ATP2A2, ...
[Intersexuality in horses]. Intersexuality is a rare congenital anomaly of horses. Diagnosis of intersexuality is difficult because there are usually no specific changes in the reproductive tract visible. During a period of five years, ten patients with reduced fertility or suspected intersexuality respectively were investigated using cytogenetic, molecular genetic, histopathological and endocrinological methods. In one case a 64,XX/63,X0 mosaicism was found. In six cases male pseudohermaphroditism was verified. These patients showed a male karyotype, testes and rudimentary parts of a female reproductive tract were prese...
Improved resolution of the comparative horse-human map: investigating markers with in silico and linkage mapping approaches. Genetic maps are extremely important tools for tracing the genes that govern economically significant traits, and microsatellites are a significant component of these. In this study, we isolated 2346 novel horse microsatellites as resources for the construction of high-density horse genetic maps. Of these 2346 markers, 339 (14.5%) horse sequences showed sequence homology to DNA sequences in the human genome, demonstrating that microsatellites as type II markers are valuable resources for developing linkage maps and that they have a potential equal to that of type I markers for developing compa...
Molecular and cytogenetic paternity testing of a male offspring of a hinny. An alleged male foal of a female mule, whose sire and grandparents were unknown, was identified for its pedigree. Parentage testing was conducted by comparing polymorphism of 12 microsatellite DNA sites and mitochondrial D-loop sequences of the male foal and the female mule. Both the sequence analysis of species-specific DNA fragments and a cytogenetic analysis were performed to identify the species of the foal and its parents. The results showed that the alleged female mule is actually a hinny, and the male foal, which possesses 62 chromosomes, qualifies as an offspring of the female hinny an...
Molecular characterization of the equine collagen, type IX, alpha 2 (COL9A2) gene on horse chromosome 2p16–>p15. The mammalian collagen, type IX, alpha 2 gene (COL9A2) encodes the alpha-2 chain of type IX collagen and is located on horse chromosome 2p16-->p14 harbouring a quantitative trait locus for osteochondrosis. We isolated a bacterial artificial chromosome (BAC) clone containing the equine COL9A2 gene and determined the complete genomic sequence of this gene. Cloning and characterization of equine COL9A2 revealed that the equine gene consists of 32 exons spanning approximately 15 kb. The COL9A2 transcript encodes a single protein of 688 amino acids. Thirty two single nucleotide polymorphisms (SN...
Alobar holoprosencephaly, mobile proboscis and trisomy 13 in a fetus with maternal gestational diabetes mellitus: a 2D ultrasound diagnosis and review of the literature. Alobar holoprosencephaly is a rare and severe brain malformation due to early arrest in brain cleavage and rotation. Methods: We report a congenital anomalous fetus with alobar holoprosencephaly, prenatally diagnosed by two-dimensional (2D) sonography at the 40 weeks of gestation. The mother was affected by gestational diabetes mellitus and was obese (BMI > 30 kg/m(2)). 2D Ultrasound depicted the cerebral malformation, cyclopy, proboscis, cardiac defects (atrial septal defect, hypoplastic left heart, anomalous communication between right ventricle and aorta) and extremities defects. The new...
A high-resolution comparative radiation hybrid map of equine chromosome 4q12-q22. In this study, we present a comprehensive 5000-rad radiation hybrid map of a 40-cM region on equine chromosome 4 (ECA4) that contains quantitative trait loci for equine osteochondrosis. We mapped 29 gene-associated sequence tagged site markers using primers designed from equine expressed sequence tags or BAC clones in the ECA4q12-q22 region. Three blocks of conserved synteny, showing two chromosomal breakpoints, were identified in the segment of ECA4q12-q22. Markers from other segments of HSA7q mapped to ECA13p and ECA4p, and a region of HSA7p was homologous to ECA13p. Therefore, we have impro...
Quantitative genetic aspects of coat color in horses. The aim of this study was to estimate genetic parameters for coat color in horses. Besides defining coat color classes (gray, chestnut, bay, and black), the phenotypes were also measured quantitatively according to standardized international procedures (Commission Internationale de l'Eclairage L*, a*, b*), where L* describes lightness, a* describes color saturation from red to green, and b* describes color saturation from yellow to blue. The total color saturation was derived from a* and b* and referred to as Chroma. A total of 294 horses from the breeds Lipizzan, Nonius, Arabian Pure Bred, Sh...
