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E G Cothran

Publications and source records attributed to E G Cothran.

At least 19 recordsLinked to original sources
PubMed2006

A lost Sorraia maternal lineage found in the Lusitano horse breed.

A common female founder individual of the Portuguese horse breeds Sorraia and Lusitano was found while conducting research on the variation of the Lusitano mitochondrial DNA lineages in relation to studbook information. We obtained 416-bp control region sequences from 16 descendents of a female Sorraia founder (Pomba) still represented in the living population of the Lusitano, according to the most recent edition of this breed's studbook. The same haplotype was found for all analysed samples and belongs to the haplogroup described by several authors as having predominantly Iberian, South American and North African haplotypes bringing new insights on the relationship between the Sorraia and the other Iberian breeds. This work illustrates how weak the boundary of breed establishment can be, especially at the same geographical region. Using the same founders in different breeds is surely one of the explanations to frequently shared haplotypes among recent breeds, resulting in a lack of consistency between mtDNA sequences and breeds and/or geographical regions.

Animals↗
PubMed2005

Major histocompatibility complex locus DRA polymorphism in the endangered Sorraia horse and related breeds.

The major histocompatibility complex (MHC) genes play well-defined roles in eliciting immune responses and combating infectious diseases. This genetic system is among the most polymorphic. The extent of genetic variation within a population has been directly correlated with fitness for many traits. The MHC class II locus DRA polymorphism was analysed in the endangered Sorraia horse, two other Portuguese and four New World horse breeds considered to be historically close to the Sorraia. Comparison of the Sorraia with other breeds demonstrated less MHC variation among Sorraia horses. If DRA polymorphism provides greater disease resistance, selective breeding to increase MHC polymorphism may increase fitness of this population.

Animals↗
PubMed2003

The epitheliogenesis imperfecta locus maps to equine chromosome 8 in American Saddlebred horses.

Epitheliogenesis imperfecta (EI) is a hereditary junctional mechanobullous disease that occurs in newborn American Saddlebred foals. The pathological signs of epitheliogenesis imperfecta closely match a similar disease in humans known as Herlitz junctional epidermolysis bullosa, which is caused by a mutation in one of the genes (LAMA3, LAMB3 and LAMC2) coding for the subunits of the laminin 5 protein (laminin alpha3, laminin beta3 and laminin gamma2). The LAMA3 gene has been assigned to equine chromosome 8 and LAMB3 and LAMC2 have been mapped to equine chromosome 5. Linkage disequilibrium between microsatellite markers that mapped to equine chromosome 5 and equine chromosome 8 and the EI disease locus was tested in American Saddlebred horses. The allele frequencies of microsatellite alleles at 11 loci were determined for both epitheliogenesis imperfecta affected and unaffected populations of American Saddlebred horses by genotyping and direct counting of alleles. These were used to determine fit to Hardy-Weinberg equilibrium for control and EI populations using Chi square analysis. Two microsatellite loci located on equine chromosome 8q, ASB14 and AHT3, were not in Hardy-Weinberg equilibrium in affected American Saddlebred horses. In comparison, all of the microsatellite markers located on equine chromosome 5 were in Hardy-Weinberg equilibrium in affected American Saddlebred horses. This suggested that the EI disease locus was located on equine chromosome 8q, where LAMA3 is also located.

Americas↗
PubMed2002

Genetic diversity of Cheju horses (Equus caballus) determined by using mitochondrial DNA D-loop polymorphism.

We used sequence polymorphism of the mitochondrial DNA D-loop (968 bp excluding the tandem repeat region) to determine genetic diversity of horses inhabiting Cheju (a southern island of Korea). Seventeen haplotypes with frequencies from 1.5 to 21.5% were found among 65 Cheju horse samples. Genetic diversity (h) of the 17 haplotypes was calculated to be 0.91, indicating that the extant Cheju horse population consists of diverse genetic groups in their maternal lineage. Phylogenetic analysis showed that 17 types of Cheju (D-loop sequences determined), 5 Mongolian, 6 Arabian, 3 Belgian, 2 Tsushima, 2 Yunnan, 1 Przewalskii, and 3 Thoroughbred horses (published sequences for the latter seven breeds) showed that Cheju horses were distributed into many different clusters in the tree. Four Mongolian horses clustered with separate Cheju horse groups, showing that some Cheju horses are clearly of Mongolian origin. The analysis of partial sequences (284 bp) of the D-loop of 109 horses showed that Thoroughbred, Mongolian, Lipizzan, and Arabian breeds are as diverse as Cheju horses. Our data together with others suggest that most horse breeds tested with reasonably sufficient numbers of samples are diverse in their maternal lineages and also are not uniquely different from each other.

Animals↗
PubMed2002

Equine epitheliogenesis imperfecta in two american saddlebred foals is a lamina lucida defect.

Necropsy of two American Saddlebred fillies diagnosed with epitheliogenesis imperfecta (EI) revealed missing patches of epithelium of the skin and oral mucosa as well as dental abnormalities. Examination of the digestive tract did not reveal signs of pyloric atresia in either foal. Histopathologic examination revealed separation of the epidermis from the dermis. In both foals a division within the lamina lucida of the basal lamina was observed by transmission electron microscopy. In comparison with an age-specific control, the ultrastructure of intact skin from the EI-affected foals showed abnormal hemidesmosomes, which lacked a subbasal plate. The morphological and ultrastructural defects observed in the EI-affected American Saddlebred foals were similar to those observed in Herlitz junctional epidermolysis bullosa-affected human newborns, which is caused by a defect in one of the subunits of laminin-5. The close similarity of lesions of the human and equine diseases suggests that EI may be caused by a laminin-5 defect.

Animals↗
PubMed2001

Linked markers exclude KIT as the gene responsible for appaloosa coat colour spotting patterns in horses.

The appaloosa coat colour pattern of the horse is similar to that caused by the rump-white (Rw) gene in the mouse. In the mouse Rw colour pattern is the result of an inversion involving the proto-oncogene c-kit (KIT). Therefore, we investigated KIT as a candidate gene that encodes the appaloosa coat colour gene (Lp) in horses. KIT plays a critical role in haematopoiesis, gametogenesis, and melanogenesis and encodes a transmembrane tyrosine kinase receptor that belongs to the PDGF/CSF-1/c-KIT receptor subfamily. Half-sib families segregating for Lp were uninformative for a reported polymorphism in KIT. However, KIT is located on horse chromosome 3 close to albumin (ALB), serum carboxylesterase (ES), vitamin D-binding protein (GC) and microsatellite markers ASB23, LEX007, LEX57, and UCDEQ437. Indeed, KIT and ASB23 were localized to ECA3q21-22.1 and 3q22.1-22.3, respectively, by fluorescent in situ hybridization. Family studies were conducted to investigate linkage of Lp to these markers using eight half-sib families in which Appaloosa stallions were mated to solid coloured mares. Linkage of Lp to the chromosome region containing ES, ALB, GC, ASB23, UCDEQ437, LEX57, and LEX007 was investigated by a multipoint linkage analysis using the computer program GENEHUNTER. LOD scores over the interval under investigation ranged from -4.28 to -12.48, with a score of -12.48 at the location for ASB23. Therefore, it was concluded that appaloosa (Lp) is not linked to any of the tested markers on ECA3, and thus Lp is unlikely to be the product of KIT.

Animals↗
PubMed2001

Characterization of expressed sequence tags generated from skin cDNA clones of Equus caballus by single pass sequencing.

A cDNA library was built using RNA extracted from the skin tissue of an adult horse. The library was primed with oligo (dT) and sequences were directionally inserted in order to produce an expression library. The library has 5.8X 10(5) plaque forming units with 99.6% recombinant phage. The average insert size is 1.3 Kbp. Three hundred and thirteen expressed sequence tags (ESTs) were generated from sequencing of the 5 prime end of randomly selected skin cDNA clones. The ESTs were sequenced on an ABI 377 using Big-Dye chemistry. A similarity search was performed on each EST using the NCBI non-redundant protein database and 206 ESTs were putatively identified. Twenty six percent of the identified ESTs were redundant. The ESTs were categorized by function. The most frequently identified functional class was translational proteins.

Animals↗
PubMed2001

Genetic variation in the feral horses of the Namib Desert, Namibia.

Genetic variation at 7 blood-group and 10 biochemical genetic loci was examined in 30 horses from a feral herd from the Namib Desert of Namibia, Africa. The observed genetic variability was extremely low compared with that found in domestic horse breeds. The low variation was most probably a result of recent small population size and a small founding population size. Genetic comparison of the Namib horses, which were of unknown origins, to domestic horse breeds, showed that the Namib horses had the highest genetic similarity to Arabian type horses, although they did not closely resemble this type of horse in conformation.

Animals↗
PubMed1999

Report of the International Equine Gene Mapping Workshop: male linkage map.

The goal of the First International Equine Gene Mapping Workshop, held in 1995, was the construction of a low density, male linkage map for the horse. For this purpose, the International Horse Reference Family Panel (IHRFP) was established, consisting of 12 paternal half-sib families with 448 half-sib offspring provided by 10 laboratories. Blood samples were collected and DNA extracted in each laboratory and sent to the Lexington laboratory (KY, USA) for dispatch in aliquots to 14 typing laboratories. In total, 161 markers (144 microsatellites, seven blood groups and 10 proteins) were tested for all families for which the sire was heterozygous. Genealogies and typing data were sent for analysis to the INRA laboratory (Jouy-en-Josas, France) according to a specific format and entered into a database with input verification and output processes. Linkage analysis was performed with the CRIMAP program. Significant linkage was detected for 124 loci, of which 95 were unambiguously ordered using a multipoint analysis with an average spacing of 14.2 CM. These loci were distributed among 29 linkage groups. A more comprehensive analysis including synteny group data and FISH data suggested that 26 autosomes out of 31 are covered. The complete map spans 936 CM.

Animals↗
PubMed1998

Polymorphism of Old Kladruber horses, a surviving but endangered baroque breed.

Analysis of MHC class I and class II polymorphism, as well as data from other polymorphic systems (non-MHC lymphocyte alloantigen, blood groups systems, biochemical polymorphisms and microsatellite loci), was used to characterize the extent and distribution of the genic polymorphism of Kladruber horses. A breed-characteristic distribution of the MHC polymorphism was found. The repertoire of defined MHC class I specificities was restricted, especially in the grey subpopulation and in stallions, but a high frequency of blanks suggests the possible existence of undetected specificities. Despite the small population size and a relatively high degree of inbreeding, high heterozygosity in MHC haplotypes has been conserved. The extent of polymorphism and the degree of heterozygosity in other loci were also relatively high. A comparison of the two existing subpopulations, grey and black, at all the loci tested, including RAPD markers, characterized them as genetically distinct, although clearly related. The genetic distances between them were of the same order of magnitude as between distinct breeds. The results may be useful in defining short-term and long-term breeding policy within the breed and for further studies of associations with disease and other traits.

Animals↗
PubMed1998

Genetic analysis of three South African horse breeds.

Genetic variability at 7 blood-group and 10 biochemical genetic loci was examined in 3 South African horse breeds, the Nooitgedacht, Boerperd and Basuto Pony. Observed heterozygosity for these breeds was intermediate for domestic horses, with the highest heterozygosity in the Boerperd and the lowest in the Basuto Pony. The 3 breeds show greater genetic similarity to each other than to other domestic horse breeds. Compared to other breeds, the South African breeds show greater genetic similarity to breeds such as the Thoroughbred, Holstein, Trakehner and Hanovarian and also to North American breeds such as the Saddlebred, Standardbred and Morgan Horse.

Alleles↗
PubMed1998

[Population genetic parameters of aboriginal Yakut horses as related to modern breeds of the domestic horse Equus caballus L].

This study was the first to analyze the polymorphic characteristics of a wide range of biochemical markers in aboriginal Yakut horses. A total of 124 alleles, including 48 alleles of seven blood-group loci and 76 alleles of ten loci for enzymes and other proteins, were studied. For these polymorphic systems, a computer analysis of the genetic distances between 85 horse breeds of different origin from all parts of the world was performed. The low level of hereditary variation in the Yakut horses confirmed that this breed is old and has long been an isolated population. Phylogenetic analysis demonstrated that Yakut horses exhibited the most genetic similarity to the breeds from the Central Asian cluster, such as Akhal Teke, Arabian, Yabou, and Caspan Pony (Iran). The dispersal route of ancient horses was revealed. It led from America through Siberia and Central Asia to Africa and Eastern Europe, where evidence of the earliest domestication of horses was found. Genetic and ecological explanations of the formation of racing and draft breeds with similar immunogenetic characteristics are advanced. These explanations agree with craniological data on fossils and with the relative rates of growth of the axial and peripheral skeletons in modern breeds. These data shed light on the initial stages of domestication of the horse, an event that was extremely important for development of the human civilization.

Animals↗
PubMed1995

Synteny-mapping horse microsatellite markers using a heterohybridoma panel.

A panel of horse-mouse heterohybridoma cells was tested for genetic markers using biochemical and polymerase chain reaction-(PCR-) based tests. Biochemical markers included phosphoglucomutase (PGM), glucose phosphate isomerase (GPI) and 6-phosphogluconate dehydrogenase (PGD). Markers detected using PCR-based tests included microsatellite markers HTG2-15, HMS 1-3, 5-8, VHL20, ECA2 and genes for equine major histocompatibility gene ELA-DRA, tumour necrosis factor alpha (TNFA) and transferrin. The results were analysed for correlation and concordance. Based on the results, five synteny groups were identified, specifically between ELA-DRA, TNFA, HMS5 and HTG5; between HTG3 and HTG13; between HTG4, HTG8 and HMS3; between HTG6 and HMS1; and between HTG7, HTG9 and HMS6. Evidence was also found for synteny between HTG12, HMS7 and ECA2, however, confirmation requires further testing. Cytogenetic evaluation of the cell lines making up the panel indicated that large metacentric chromosomes were preferentially lost or tended to break at the centromere. Consequently, the results from this analysis can be used to identify synteny, but not to exclude synteny.

Animals↗
PubMed1994

A new buffer system for acid PAGE typing of equine protease inhibitor.

A new buffer system for acid PAGE typing of protease inhibitor (Pi) is described. This buffer system replaces pyridine and cacodylic acid with L-histidine and MES, making the buffer less toxic and less expensive than the acid PAGE system commonly used but with no loss of resolution.

Animals↗
PubMed1994

A new phenogroup in the horse D system of red cell alloantigens found in the Caspian pony.

A new D blood group phenogroup consisting of the specificities adeo was observed in a stallion family of Caspian ponies from Iran. An additional six undescribed genetic variants were seen in a total of 82 Iranian horses. This result suggests extensive new genetic variation may be present in domestic horses from geographic regions that have not yet received scientific attention.

Animals↗