Browsing by Subject "equine"

Now showing 1 - 4 of 4
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    Forage quality and blood metabolites of horses grazing alfalfa, cool-season perennial grass, and teff
    (2018-07) DeBoer, Michelle
    The impact of forage species on blood metabolites concentrations of grazing horses (Equus caballus L.) is unknown. However, these differences can be crucial as plasma amino acid (AA) concentrations as well as the glucose and insulin response of grazing horses can be indicators of nutritional status or metabolic health. As a result, the objectives of these studies were to determine the impact of different forage species on plasma AA concentrations, protein synthesis, as well as the glucose and insulin response across seasons. Research was conducted in May (spring), July (summer), September (fall), and late October (late-fall) in St. Paul, MN in 2016. However, the data collected was divided into three different studies (1) July samples taken during the first 4 hours were used to evaluate the forage and plasma AA concentrations (2) samples collected in July and September were included in the glucose and insulin response analysis of the regular grazing season and (3) May and October samples were used to analyze the glucose and insulin response during the extended grazing season. Forage treatments included alfalfa (Medicago sativa L.), a mixed perennial cool-season grass (CSG) and teff (Eragrostis tef [Zucc.] Trotter), however, not all forage species were grazed every season. Alfalfa and CSG were grazed in May while CSG and teff were grazed during the October, with all three species grazed in July and September. During these times, forages were grazed by six horses (24 ± 2 yr) randomly assigned to a forage in either a Latin-square or cross-over design. Jugular catheters were inserted 1 h prior to the start of grazing and horses had access to pasture starting at 08:00 h for either 4 or 8 h depending on the season. Jugular venous blood samples were collected from each horse prior to being turned out (0 h) and then at 2 hour intervals following turnout. Plasma and serum samples were collected and analyzed for AA, glucose, and insulin. Corresponding forage samples were taken by hand harvest. Equine muscle satellite cell cultures were treated with sera from grazing horses to assess de novo protein synthesis. Seasons were analyzed separately and data were analyzed using the MIXED procedure in SAS with P ≤ 0.05. When evaluating forage, AA were generally lowest in teff and highest in CSG (P ≤ 0.05). Significant differences in threonine concentration in the plasma were observed; there was no effect on de novo protein synthesis of cultured equine myotubes treated with plasma obtained from the grazing horses (P ≥ 0.20). As a result, although there were significant differences in forage AA content only plasma threonine concentration was different at 4 h with no effect on protein synthesis of cultured equine satellite cells. When evaluating the glucose and insulin response during the regular grazing season, teff generally had lower (P ≤ 0.05) equine digestible energy (DE), crude protein (CP) and nonstructural carbohydrates (NSC) compared to the other forages. Differences in peak insulin were observed between horses grazing CSG and teff during the fall grazing (P ≤ 0.05). Additionally, when evaluating the extended grazing season, teff had lower NSC than CSG in the late-fall (P ≤ 0.05) with subsequently lower average glucose, average insulin, and peak insulin in horses grazing teff compared to CSG (P ≤ 0.05).These results suggest grazing teff could lower the glucose and insulin response of some horses, specifically in the fall and late-fall, and may provide an alternative forage for horses with metabolic concerns,
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    Immune-Mediated Myositis in Horses: From phenotype to genotype
    (2016-05) Durward-Akhurst, Sian
    Background: Equine immune-mediated myositis (IMM) is a painful and debilitating condition of predominantly Quarter Horse (QH) and related breeds. The epaxial and gluteal muscles are most severely affected and muscle atrophy can be dramatic, with 50% of the affected muscle mass being lost in <72 hours. Diagnosis is based on a muscle biopsy of affected muscles and the identification of lymphocytes invading myofibers and in some cases surrounding blood vessels. The pathophysiology is presumed to be immune-mediated, but further evidence is needed to confirm this. Abnormal expression of major histocompatibility Complex (MHC) has been identified on muscle fibers from most human IMMs and provides the most consistent indication of an immune-mediated mechanism. The restriction of IMM to primarily QH and related breeds, particularly in certain bloodlines suggests that there is a genetic susceptibility underlying IMM. Hypothesis: Quarter Horses are genetically susceptible to an immune mediated myositis that is characterized by abnormal expression of MHC class I and/or class II on the sarcolemma of myofibers. Specific Aim 1: To determine if abnormal MHC class I and II expression is present on the sarcolemma of myofibers of horses with active IMM in the presence or absence of myofiber lymphocytic infiltrates. Specific Aim 2: To characterize the subtypes of lymphocytes in the myofibers of horses with active IMM and correlate this with MHC expression. Methods: Immunohistochemical staining for MHC I, II, CD4+, CD8+, CD20+ lymphocytes was performed on archived muscle samples of IMM (21 horses) and controls (3 healthy and 6 disease controls). Scores were given for MHC I and II and for lymphocytic subtypes. Results: A degree of sarcolemmal MHC I and II expression was present in 81% and 71% of IMM horses, respectively. CD4+, CD8+, and CD20+ cells were present in 20/21 IMM horses with a CD4+ predominance in 48% of cases. MHC I score was positively correlated with MHC II (r = 0.89, p = <0.001) and CD8+ (r= 0.64, p = 0.002) and CD20+ (r = 0.66, p = 0.001) lymphocyte and macrophage scores (r = 0.70, p = <0.001). MHC II scores were positively correlated to CD8+ (r = 0.59, p = 0.005), CD20+ (r = 0.61, p = 0.004) lymphocyte and macrophage (r = 0.70, p = <0.001) scores. Specific Aim 3: To determine if equine IMM is significantly associated with a region of the equine genome using a genome-wide association (GWA) study. Methods: DNA was extracted from blood and muscle of 36 IMM horses and 54 healthy controls of QH-related breeds that were housed in similar environments. Sequencing was performed on equine 50K and 70K single nucleotide polymorphism (SNP) arrays. A GWA was performed across 40,811 SNPs that passed quality control. To account for elevated genomic inflation, statistical analysis was performed using GEMMA and GRAMMAR-GC software. Results: A significant association was identified between IMM and a 2 MB region on equine chromosome 11. Five SNPs in 3 haplotype blocks reached genome-wide significance using the 2 different statistical methods to account for population stratification. The significant region contains 6 myosin heavy chain genes expressed in skeletal muscle, including MYH2, which has been associated with a human IMM. Conclusions: Equine IMM is characterized by MHC I and II expression on the sarcolemma of myofibers during an acute CD4+ and CD8+ lymphocytic inflammatory episode. There is an approximately 2MB region on equine chromosome 11 that is associated with the development of the disease. Sequencing of the MYH genes in IMM cases and unaffected controls is warranted to identify variants that cause IMM in Quarter Horses.
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    Molecular bases of equine polysaccharide storage myopathies
    (2015-04) Teixeira, Raffaella
    Polysaccharide Storage Myopathy (PSSM) is a form of glycogen storage disease in horses, characterized by abnormal polysaccharide inclusions in skeletal muscle. PSSM1 is caused by a dominant gain of function mutation in the GYS1 gene. PSSM1 horses can metabolize glycogen and have a normal flux of metabolites through glycolysis during maximal exercise, yet these horses demonstrate exercise intolerance, painful muscle cramping, and rhabdomyolysis during sub-maximal exercise. The link between excessive muscle glycogen, abnormal polysaccharide and rhabdomyolysis during sub-maximal exercise is less clear. To evaluate the changes in muscle that lead to this energy deficit, muscle gene expression profiles before and after a controlled exercise trial were evaluated in PSSM1 cases and controls by RNASeq. 201 genes were differentially expressed between cases and controls pre-trial, 301 genes were differently expressed between cases and controls pre-exercise (end of trial) and 803 genes were differentially expressed between cases and controls post-exercise (end of the trial). Gene set enrichment analysis revealed enrichment in pathways involving mitochondria biogenesis, oxidative phosphorylation, fatty acid metabolism, glycogen and glucose metabolism. DAVID was used to cluster the top differentially expressed genes based on their functional annotation. Clusters involved in inflammation were overrepresented. A second form of PSSM (PSSM2) has also been described. The mutation responsible for PSSM2 is unknown. Genome wide association data revealed significant markers associated with PSSM2 on equine chromosome 18 but no variants associated with PSSM2 were identified after extensive investigation of this region using a combination of target and whole genome sequencing in cases and controls. Imputation was then performed to increase the number of SNP markers in the initial GWA from 54,000 to close to 1.8 million markers, revealing new regions associated with PSSM2 on chromosomes 27 and 11. Haplotype analysis supported the association only on chromosome 11. The region of ECA11 encompasses several annotated genes. Next generation sequencing data from cases and controls revealed non-synonymous mutations in the phosphoribosylformylglycinamidine synthase gene in 2 out of 3 cases and none of the controls, identifying a new region in which to focus our efforts to define the genetic basis for PSSM2.
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    VCF truth sets of variants inserted into simulated equine genomes (90 VCFs)
    (2024-09-26) Marlowe, Jillian L.; Durward-Akhurst, Sian A.; McCue, Molly E.; marlo072@umn.edu; Marlowe, Jillian; University of Minnesota Equine Genetics and Genomics Laboratory
    Simulated data is an inexpensive and timely alternative to the generation of novel whole genome sequence (WGS) data. We generated artificial DNA sequence reads representing simulated equine genomes which contain predetermined genetic variants that can be used as a benchmark dataset to evaluate genomic processing tools. The VCFs contained in this repository contain the benchmark set of genetic variants for each of the simulated genomes that were created. These VCFs can be used in conjunction with the simulated sequences which are also publicly available to evaluate WGS processing tools.