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Background: Thoroughbred horses are the most expensive domestic animals, and their running ability and knowledge about their muscle-related diseases are important in animal genetics. While the horse reference genome is available, there has been no large-scale functional annotation of the genome using expressed genes derived from transcriptomes.
Results: We present a large-scale analysis of whole transcriptome data. We sequenced the whole mRNA from the blood and muscle tissues of six thoroughbred horses before and after exercise. By comparing current genome annotations, we identified 32,361 unigene clusters spanning 51.83 Mb that contained 11,933 (36.87%) annotated genes. More than 60% (20,428) of the unigene clusters did not match any current equine gene model. We also identified 189,973 single nucleotide variations (SNVs) from the sequences aligned against the horse reference genome. Most SNVs (171,558 SNVs; 90.31%) were novel when compared with over 1.1 million equine SNPs from two SNP databases. Using differential expression analysis, we further identified a number of exercise-regulated genes: 62 up-regulated and 80 down-regulated genes in the blood, and 878 up-regulated and 285 down-regulated genes in the muscle. Six of 28 previously-known exercise-related genes were over-expressed in the muscle after exercise. Among the differentially expressed genes, there were 91 transcription factor-encoding genes, which included 56 functionally unknown transcription factor candidates that are probably associated with an early regulatory exercise mechanism. In addition, we found interesting RNA expression patterns where different alternative splicing forms of the same gene showed reversed expressions before and after exercising.
Conclusion: The first sequencing-based horse transcriptome data, extensive analyses results, deferentially expressed genes before and after exercise, and candidate genes that are related to the exercise are provided in this study.
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http://dx.doi.org/10.1186/1471-2164-13-473 | DOI Listing |
PLoS Genet
September 2025
Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota, United States of America.
MicroRNAs (miRNAs) are essential regulators of gene expression, yet few comprehensive databases exist for miRNA expression in non-model species, limiting our ability to characterize their roles in gene regulation, development, and disease. Similarly, isomiRs - length and sequence isoforms of canonical miRNAs with potentially altered regulatory targets and functions - have received even less attention in non-model species, including the horse, leaving a critical gap in our understanding of their biological significance. To address these challenges, we developed an open-source, containerized pipeline for identifying and quantifying miRNAs and isomiRs (FARmiR: Framework for Analysis and Refinement of miRNAs), and an associated interactive browser (AIMEE: Animal IsomiR and MiRNA Expression Explorer).
View Article and Find Full Text PDFBackground: Standing fracture repair has become established as an acceptable technique with a good long-term prognosis. However, no study has compared racing outcomes with case-matched controls.
Objectives: To compare racing outcomes between a large dataset of horses undergoing standing fracture repair against case-matched controls.
J Equine Vet Sci
September 2025
Genetic Analysis Department, Laboratory of Racing Chemistry, 1731-2 Tsurutamachi, Utsunomiya, Tochigi 320-0851, Japan.
Background: Thoroughbreds have been maintained as a closed breed for over 300 years since the crossbreeding between Arabian stallions and English mares. Despite interest in germline de novo mutations across species, their frequency in horses, particularly in Thoroughbreds, remains largely unexplored.
Aims/objective: This study aimed to identify de novo mutations in Thoroughbreds and estimate their frequency within a genetically closed population.
BMC Genomics
September 2025
Wageningen University & Research Animal Breeding and Genomics, P.O. Box 338, Wageningen, 6700 AH, the Netherlands.
Background: In horses, genetic diversity is predominantly observed between breeds, with little variation within breeds. The studbooks of the two largest horse populations in the Netherlands, the Dutch Warmblood horse and Friesian horse population, have ongoing conservation projects including collecting large-scale genotype and sequence data. The current reference genome, derived from a Thoroughbred horse can lead to bias in genetic analyses of other horse breeds.
View Article and Find Full Text PDFJ Equine Vet Sci
September 2025
School of Life and Environmental Sciences, Faculty of Science, University of Sydney, NSW 2006, Australia. Electronic address:
Background: The ongoing discussion surrounding the well-being of retired racehorses underscores the importance of implementing effective rehoming strategies that prioritise animal welfare. A significant knowledge gap persists regarding whether a horse's success in racing can be used to reliably predict its performance in different equestrian sports upon retirement from racing.
Aims/objectives: To examine the association between racehorse performance metrics and eventing metrics in off-the-track Thoroughbreds that compete in eventing within Australia.