Equine Genomics - Enhanced Performance Profiling


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International researchers have recently decoded the genome of the domestic horse, Equus caballus. Interestingly, they reported that the horse genome structure is remarkably similar to the human genome (Wade et.al 2009). To date an additional nine domesticated horse breeds have also been sequenced. These combined efforts have identified around one million single nucleotide polymorphisms (SNPs) (Wade et al. 2008). The focus now needs to be on the functional annotation of the horse genome. This is the approach that Equine Genomics is now taking.

The transcriptome or expression of RNA transcripts is a reflection or a "snap-shot" of the cellular metabolism at a particular point in time. The horse's transcriptome is not static it adapts to accommodate changing environmental conditions including growth and development. Many of the biological regulations assuring these functions occur are at the level of transcriptional control of the genes involved in these processes. Therefore knowledge of the genes and their expression in response to an environmental change such as exercise, nutrition or disease states for example provides information on the specific pathways involved. It is known that the transcripts expressed by a horse pre and post exercise generate different expression profiles (McGivney et al., 2010).

For example, it is known that strenuous exercise induces a pattern of hormonal, nervous and immunological responses. The non-specific immune response involves a number of pro-inflammatory cytokines, such as tumour necrosis factor alpha (TNF-alpha), interlukin (IL-6 and IL-1 a /Il- b). It is also know that alterations in metal trace elements have been identified following exercise. Copper (Cu) and zinc (Zn) have an effect on immune function and plasma concentrations of these elements are altered in inflammatory states (Giacconi et al., 2008; Malavolta et al., 2010). An elevated serum Cu concentration induces oxidative stress, which promotes the inflammatory response (Bo et al., 2008), whereas a recued Zn concentration limits the antioxidant response, contributing to inflammation (Giacconi et al., 2008).

Transcriptome analysis of peripheral blood is of great interest; significant differences between samples obtained in a minimally invasive and cost effective manner can be translated into gene signatures of nutritional status, toxicity, and drug response and disease stage. Blood comes into contact with almost every tissue and organ and due to its cellular composition it can reflect both physiological and pathogenic stimuli. For example, gene expression differences in peripheral whole blood have been used to determine signatures related to many diseases including neurological disorders where significant correlation has been found between blood and brain expression. It has also been demonstrated that gene expression profiles in various tissues from the same disease were more similar than gene expression profiles from identical tissues from different diseases. It is also known that 80% of the genes expressed in peripheral blood cells are shared with other important tissues. This data shows that transcriptome analysis of blood is often more informative even when the originating pathology stems from a different tissue.

Until now, relatively few genes have been identified relating to athletic phenotypes. This is in spite of the physical and physiological adaptions underlying athleticism being well defined (Booth et al., 1998). Muscle is the most critical tissue for athletic performance comprising 55% of the horse's total body mass (Gu et al., 2009 and Gunn 2010) having remarkable functional and structural plasticity (Booth et al., 1998). Interestingly over 90 heritable conditions in horses have corresponding human disorders (Booth et al., 1998 and Das et al., 2010) including muscle disorders. Humans and horses share common clinical, histopathological and molecular features (Eisen et al., 2004; Wade et al., 2009; Poole 2004).

Transcriptome profiling will provide detailed information in relation to equine genes, their expression and how this expression is affecting the health and performance of the horse.



Transcriptome profile
Transcriptome Profile
Pre-exercise and Post exercise
Gene Expression