[show abstract][hide abstract] ABSTRACT: The horse is an optimal model organism for studying the genomic response to exercise-induced stress, due to its natural aptitude for athletic performance and the relative homogeneity of its genetic and environmental backgrounds. Here, we applied RNA-sequencing analysis through the use of SOLiD technology in an experimental framework centered on exercise-induced stress during endurance races in equine athletes. We monitored the transcriptional landscape by comparing gene expression levels between animals at rest and after competition. Overall, we observed a shift from coding to non-coding regions, suggesting that the stress response involves the differential expression of not annotated regions. Notably, we observed significant post-race increases of reads that correspond to repeats, especially the intergenic and intronic L1 and L2 transposable elements. We also observed increased expression of the antisense strands compared to the sense strands in intronic and regulatory regions (1 kb up- and downstream) of the genes, suggesting that antisense transcription could be one of the main mechanisms for transposon regulation in the horse under stress conditions. We identified a large number of transcripts corresponding to intergenic and intronic regions putatively associated with new transcriptional elements. Gene expression and pathway analysis allowed us to identify several biological processes and molecular functions that may be involved with exercise-induced stress. Ontology clustering reflected mechanisms that are already known to be stress activated (e.g., chemokine-type cytokines, Toll-like receptors, and kinases), as well as "nucleic acid binding" and "signal transduction activity" functions. There was also a general and transient decrease in the global rates of protein synthesis, which would be expected after strenuous global stress. In sum, our network analysis points toward the involvement of specific gene clusters in equine exercise-induced stress, including those involved in inflammation, cell signaling, and immune interactions.
PLoS ONE 12/2013; 8(12):e83504. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: In this study, we examine the population structure and inbreeding level of the Italian Lipizzan horse breed by means of AFLP fingerprinting and SSR genotyping. A total of 245 AFLP marker alleles were scored across all horses (n=140) living in the Italian Lipizzan stud in 2007, and microsatellite analysis was performed on all mares (n=42) and stallions (n=7) by genotyping at 30 SSR marker loci. A total of 53 (21.6%) AFLP marker alleles were scored as polymorphic among the animals, with a mean frequency of 0.722. Based on this subset of markers, 123 animals were assigned to three distinct subgroups of 44, 41 and 38 animals, respectively, each one showing a within-subgroup mean Dice's genetic similarity around 86% (standard error<0.3%), whereas the remaining 17 animals that displayed an admixed ancestry (membership<45%) were clustered apart, with a between-subgroup genetic similarity spanning from 80% to 83%. All animals could be discriminated from each other on the basis of multi-locus DNA fingerprints. However, only 6% of the genetic variation was found among subgroups, as supported by the low fixation index Fst=0.058. In the mares and stallions, a total number of 146 marker alleles were detected across the assayed SSR loci, with a mean marker allele frequency of 0.485 and an observed and effective number of alleles per locus of 4.710 and 2.921, respectively. The Nei's unbiased heterozygosity for the Italian Lipizzan horse breed was equal to H=63.5% and the Wright's inbreeding coefficient had an average value of Fis=−0.133, suggesting an excess of heterozygosity. Significant (P<0.01) pair-wise linkage disequilibria between AFLP marker alleles as well as between SSR marker alleles were found in the whole Lipizzan population. It was found that mating plan optimization could reduce the average relatedness to 0.619, a lower value than that obtained by casual unions between stallions and mares (0.740). The findings described here will be useful for the indirect selection of animals based on markers linked to traits of interest and for the assessment of conservation priorities and strategies.
[show abstract][hide abstract] ABSTRACT: Intense selective pressures applied over short evolutionary time have resulted in homogeneity within, but substantial variation among, horse breeds. Utilizing this population structure, 744 individuals from 33 breeds, and a 54,000 SNP genotyping array, breed-specific targets of selection were identified using an F(ST)-based statistic calculated in 500-kb windows across the genome. A 5.5-Mb region of ECA18, in which the myostatin (MSTN) gene was centered, contained the highest signature of selection in both the Paint and Quarter Horse. Gene sequencing and histological analysis of gluteal muscle biopsies showed a promoter variant and intronic SNP of MSTN were each significantly associated with higher Type 2B and lower Type 1 muscle fiber proportions in the Quarter Horse, demonstrating a functional consequence of selection at this locus. Signatures of selection on ECA23 in all gaited breeds in the sample led to the identification of a shared, 186-kb haplotype including two doublesex related mab transcription factor genes (DMRT2 and 3). The recent identification of a DMRT3 mutation within this haplotype, which appears necessary for the ability to perform alternative gaits, provides further evidence for selection at this locus. Finally, putative loci for the determination of size were identified in the draft breeds and the Miniature horse on ECA11, as well as when signatures of selection surrounding candidate genes at other loci were examined. This work provides further evidence of the importance of MSTN in racing breeds, provides strong evidence for selection upon gait and size, and illustrates the potential for population-based techniques to find genomic regions driving important phenotypes in the modern horse.
[show abstract][hide abstract] ABSTRACT: Athletic performance is both a stress factor and an adaptive response to exercise that may be modulated by training, reduce inflammation and help prevent disease. Studies on the endocrinology of exercise and training have demonstrated the existence of an integrated metabolic network of hormone and cytokine regulation. Subsequent molecular studies have shown that repeated bouts of exercise may establish new basal levels of gene expression at rest. The Thoroughbred horse may be a useful 'exercise model' for inter-individual comparisons between subjects with homogeneous genetic and environmental backgrounds and similar exercise management practices. In this study, the effects of training and acute effort on gene expression were evaluated with a real time PCR approach in athletic (n=10) and sedentary horses (n=9), using a previously characterised panel of genes known to be highly modulated during effort (CXCL2, TLR4, IL1β, IL8, IL1RII, IL18, IL6 and CEBPβ). A 'rest comparison' was performed to evaluate a training effect in both groups while a 'race comparison' was performed in athletic horses only (before, immediately after, and 12h after racing) to determine the effect of acute effort. The results indicated that many of the investigated genes (TLR4, IL1β, IL1RII, IL18, IL6 and CEBPβ) were expressed to a greater extent in athletic horses compared to sedentary animals when both were at rest. However, a time-course comparison in the athletic horses revealed that genes exhibiting the highest levels of expression at rest did not show significant changes after the race. The findings suggested that training may exert a conditioning on gene expression at rest leading to a more prompt response to exercise-induced stress in Thoroughbreds.
The Veterinary Journal 09/2012; · 2.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: Equine infectious anaemia virus (EIAV) is classified within the Retroviridae and, like other lentivirus, has the propensity for considerable antigenic variation. An extensive phylogenetic analysis in Bayesian fashion, with significant amounts of new EIAV gag sequence information, revealed a strong geographic compartmentalization clearly related to the phylogeographic history of modern horses, pointing out that New World EIAV strains form a distinct group with a potentially common origin. This evidence suggests that a single founder event may have occurred during the reintroduction of horses to the Americas by European colonists in the 15th century, a possibility that raises many interesting scenarios with implications for all evolutionary and ecological studies.
Virus Research 11/2011; 163(2):656-9. · 2.75 Impact Factor
[show abstract][hide abstract] ABSTRACT: A 15-year-old Belgian gelding was referred for fever, depression, and respiratory distress. Lung biopsy revealed interstitial fibrosis consistent with chronic interstitial pneumonia. Equid herpesvirus 5 (EHV-5) DNA was detected by polymerase chain reaction (PCR) in bronchoalveolar lavage and biopsy specimens. A presumptive diagnosis of equine multinodular pulmonary fibrosis (EMPF) was made, and the horse was administered a systemic treatment with corticosteroids and antiviral drugs. Despite initial clinical improvement, 4 weeks later, the condition of the horse rapidly deteriorated, and the animal was euthanized. Postmortem examination confirmed the presumptive diagnosis of EMPF. The EHV-5 DNA load in different tissues was estimated using a quantitative real-time PCR. Lung had a remarkable viral load, higher than in other organs, especially within the pulmonary fibrotic nodules, and a linkage between high viral burden and the most severely affected tissues was observed. The results suggest that the quantitative real-time PCR is a useful tool to quantify the EHV-5 load in different organs and to understand the relationship between EHV-5 and EMPF. The bronchoalveolar lavage was determined to be a good clinical sample to estimate the EHV-5 load in lung.
Journal of veterinary diagnostic investigation: official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc 07/2011; 23(4):802-6. · 1.18 Impact Factor
[show abstract][hide abstract] ABSTRACT: Horses and humans share a natural proclivity for athletic performance. In this respect, horses can be considered a reference species in studies designed to optimize physical training and disease prevention. In both species, interleukin-6 (IL-6) plays a major role in regulating the inflammatory process induced during exercise as part of an integrated metabolic regulatory network. The aim of this study was to compare IL-6 and IL-6 receptor (IL-6R) mRNA expression in peripheral blood mononuclear cells (PBMCs) in trained and untrained humans and horses.
Nine highly trained male swimmers (training volume: 21.6 ± 1.7 h/wk in 10-12 sessions) were compared with two age-matched control groups represented by eight lightly trained runners (training volume: 6.4 ± 2.6 h/wk in 3-5 sessions) and nine untrained subjects. In addition, eight trained horses (training volume: 8.0 ± 2.1 h/wk in 3-4 sessions) were compared with eight age-matched sedentary mares. In humans, IL-6 mRNA levels in PBMCs determined by quantitative reverse transcription-polymerase chain reaction were significantly higher in highly trained subjects, whereas IL-6R expression did not differ among groups. In horses, transcripts of both IL-6 and IL-6R were significantly up-regulated in the trained group.
Up-regulation of IL-6R expression in PBMCs in horses could reflect a mechanism that maintains an adequate anti-inflammatory environment at rest through ubiquitous production of anti-inflammatory cytokines throughout the body. These findings suggest that the system that controls the inflammatory response in horses is better adapted to respond to exercise than that in humans.
[show abstract][hide abstract] ABSTRACT: A large proportion of mammalian genomes is represented by transposable elements (TE), most of them being long interspersed nuclear elements 1 (LINE-1 or L1). An increased expression of LINE-1 elements may play an important role in cellular stress-related conditions exerting drastic effects on the mammalian transcriptome. To understand the impact of TE on the known horse transcriptome, we masked the horse EST database, pointing out that the amount is consistent with other major vertebrates. A previously developed transcript-derived fragments (TDFs) dataset, deriving from exercise-stimulated horse peripheral blood mononuclear cells (PBMCs), was found to be enriched with L1 (26.8% in terms of bp). We investigated the involvement of TDFs in exercise-induced stress through bioinformatics and gene expression analysis. Results indicate that LINE-derived sequences are not only highly but also differentially expressed during physical effort, hinting at interesting scenarios in the regulation of gene expression in relation to exercise.
[show abstract][hide abstract] ABSTRACT: Equid herpesvirus 5 (EHV-5) infection was detected in a farm in Italy by the use of a semi-nested polymerase chain reaction (PCR) targeting glycoprotein B of EHV-5 on nasal swabs and blood samples of clinically healthy and randomly selected Lipizzaner horses (n = 55). Twenty-five horses at the age of 4-17 years and 30 at an age of 1-3 years were sampled once. The association of the infection with these age-groups and the gender of the horses was investigated. The apparent prevalence of EHV-5 infection was significantly different between age-cohorts: it was higher in the younger group of horses with 73,3% and 80% positives in nasal swabs and blood respectively, compared to 40% of nasal swabs and 20% of blood in the older horses. An age-dependence therefore was observed: the young age is more frequently associated with EHV-5 infection.
Veterinary Research Communications 12/2010; 34(8):703-8. · 1.08 Impact Factor
[show abstract][hide abstract] ABSTRACT: It is known that moderate physical activity may have beneficial effects on health, whereas strenuous effort induces a state resembling inflammation. The molecular mechanisms underlying the cellular response to exercise remain unclear, although it is clear that the immune system plays a key role. It has been hypothesized that the physio-pathological condition that develops in athletes subjected to heavy training is caused by derangement of cellular immune regulation. The purpose of the present study was to obtain information on endurance horse gene transcription under strenuous conditions and to identify candidate genes causing immune system derangement. We performed a wide gene expression scan, using microarray technology, on peripheral blood mononuclear cells of ten horses chosen from high-level participants in national and international endurance races. The use of three different timepoints revealed changes in gene expression when post-effort samples (T1, taken immediately after the race; and T2, taken 24 h after the race) were compared with basal sample (T0, at rest). Statistical analysis showed no differences in gene expression between T0 and T2 samples, indicating complete restoration of homeostasis by 24 h after racing, whereas T1 showed strong modulation of expression, affecting 132 genes (97 upregulated, 35 downregulated). Ingenuity pathway analysis revealed that the main mechanisms and biofunctions involved were significantly associated with immunological and inflammatory responses. Real-time PCR was performed on 26 gene products to validate the array data.
[show abstract][hide abstract] ABSTRACT: The application of molecular diagnostic techniques along with nucleotide sequence determination to permit contemporary phylogenetic analysis of European field isolates of equine infectious anemia virus (EIAV) has not been widely reported. As a result, of extensive testing instigated following the 2006 outbreak of equine infectious anemia in Italy, 24 farms with a history of exposure to this disease were included in this study. New PCR-based methods were developed, which, especially in the case of DNA preparations from peripheral blood cells, showed excellent correlation with OIE-approved agar gel immunodiffusion (AGID) tests for identifying EIAV-infected animals. In contrast, the OIE-recommended oligonucleotide primers for EIAV failed to react with any of the Italian isolates. Similar results were also obtained with samples from four Romanian farms. In addition, for the first time complete characterization of gag genes from five Italian isolates and one Romanian isolate has been achieved, along with acquisition of extensive sequence information (86% of the total gag gene) from four additional EIAV isolates (one Italian and three Romanian). Furthermore, in another 23 cases we accomplished partial characterization of gag gene sequences in the region encoding the viral matrix protein. Analysis of this information suggested that most Italian isolates were geographically restricted, somewhat reminiscent of the "clades" described for human immunodeficiency virus type 1 (HIV-1). Collectively this represents the most comprehensive genetic study of European EIAV isolates conducted to date.
Journal of clinical microbiology 11/2010; 49(1):27-33. · 4.16 Impact Factor
[show abstract][hide abstract] ABSTRACT: The stress response is a critical factor in the training of equine athletes; it is important for performance and for protection of the animal against physio-pathological disorders.In this study, the molecular mechanisms involved in the response to acute and strenuous exercise were investigated using peripheral blood mononuclear cells (PBMCs).
Quantitative real-time PCR (qRT-PCR) was used to detect modifications in transcription levels of the genes for matrix metalloproteinase-1 (MMP-1) and interleukin 8 (IL-8), which were derived from previous genome-wide expression analysis. Significant up-regulation of these two genes was found in 10 horses that had completed a race of 90-120 km in a time-course experimental design.
These results suggest that MMP-1 and IL-8 are both involved in the exercise-induced stress response, and this represents a starting point from which to understand the adaptive responses to this phenomenon.
[show abstract][hide abstract] ABSTRACT: Fifteen unweaned thoroughbred foals, born on a stud farm to vaccinated mares, were clinically monitored during their first six months of life and repeatedly tested for equine herpesvirus type 1 (EHV-1) and equine herpesvirus type 4 (EHV-4). Nasopharyngeal swabs and blood samples were collected and screened respectively by PCR and seroneutralisation to detect the presence of the virus, explore its role as a possible cause of respiratory disease, and to assess the efficiency of the pcr for the diagnosis of this disease. The foals were divided into three groups on the basis of their clinical signs and whether they had seroconverted to EHV-1 and/or EHV-4: first, foals with no clinical signs of disease that had not seroconverted; secondly, foals with clinical signs that had seroconverted, and thirdly, foals with clinical signs that had not seroconverted. The results indicated that the viruses circulated on the stud farm despite stringent vaccination regimens against them, and confirmed their association with respiratory disease. The absence of significantly different pcr results among the three groups of foals showed that the pcr was effective in confirming the circulation of the viruses on the premises without being particularly helpful as a diagnostic tool.
The Veterinary record 04/2008; 162(11):337-41. · 1.80 Impact Factor
[show abstract][hide abstract] ABSTRACT: Adequate stress response is a critical factor during athlete horses' training and is central to our capacity to obtain better performances while safeguarding animal welfare. In order to investigate the molecular mechanisms underlying this process, several studies have been conducted that take advantage of microarray and quantitative real-time PCR (qRT-PCR) technologies to analyse the expression of candidate genes involved in the cellular stress response. Appropriate application of qRT-PCR, however, requires the use of reference genes whose level of expression is not affected by the test, by general physiological conditions or by inter-individual variability.
The expression of nine potential reference genes was evaluated in lymphocytes of ten endurance horses during strenuous exercise. These genes were tested by qRT-PCR and ranked according to the stability of their expression using three different methods (implemented in geNorm, NormFinder and BestKeeper). Succinate dehydrogenase complex subunit A (SDHA) and hypoxanthine phosphoribosyltransferase (HPRT) always ranked as the two most stably expressed genes. On the other hand, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), transferrin receptor (TFRC) and ribosomal protein L32 (RPL32) were constantly classified as the less reliable controls.
This study underlines the importance of a careful selection of reference genes for qRT-PCR studies of exercise induced stress in horses. Our results, based on different algorithms and analytical procedures, clearly indicate SDHA and HPRT as the most stable reference genes of our pool.
[show abstract][hide abstract] ABSTRACT: The knowledge of molecular mechanisms of stress response in athlete horses can allow us to plan an appropriate and high-grade training to obtain better performance and to preserve horse welfare. It is well known that excessive muscular exercise can lead to a number of responses which may be associated with modification of the mRNA levels for a number of metabolic genes such as those involved in the immune response. In the present study cDNA-AFLP technique was applied to Arab endurance horses under stressing conditions to visualise variations of transcriptional profiles; 49 transcript derived fragments (TDFs), differentially expressed, were cloned and sequenced. Four of these showed high sequence similarity with genes probably involved in exercise-induced stress response and resulted to be not sequenced in the horse. Their modulation was confirmed by RT-PCR and the full-length transcripts were isolated by RACE-PCR. The mRNAs sequences obtained were included in the GenBank database as Equus caballus interleukin 8 (IL8), E. caballus retinoblastoma binding protein 6 mRNA (RBBP6), E. caballus eukaryotic translation initiation factor 4 gamma 3 (eIF4G3) and E. caballus heat shock protein 90 (Hsp90). The expression pattern of these genes was verified in other endurance horses under stressing conditions, strengthening the hypothesis of their real involvement in exercise stress-induced response.
Research in Veterinary Science 07/2007; 82(3):335-43. · 1.77 Impact Factor
[show abstract][hide abstract] ABSTRACT: The identification of differentially expressed genes is a fundamental prerequisite for understanding the molecular regulation of most physiological and pathological processes. Among the procedures employed to compare mRNA populations, those that are gel-based appear to hold great promise and are considered excellent tools for studying gene expression in species, such as the equine one, for which little genomic information is available. In the present study, we evaluated two techniques for studying mRNA profiles in horse tissue, one referred to the cDNA-amplified fragment length polymorphism (AFLP) that we called C-AFLP (classical cDNA-AFLP) protocol and the other to ordered differential display (ODD) with some modifications that we named S-AFLP (systematic cDNA-AFLP). Both techniques can be applied in live animals because of the small amount of sample required. We applied the S-AFLP to investigate horse transcript profile modifications during physical exercise. We found two transcripts that are mostly expressed during exercise and immediately after the end of it.
Research in Veterinary Science 11/2005; 79(2):105-12. · 1.77 Impact Factor