Equus caballus Transcriptome or Gene expression

The physiological changes associated with the varying hormonal environment throughout the oestrous cycle have been analysed in several species. These changes are linked to the many functions the uterus needs to fulfil, such as clearing contaminants introduced via breeding and supporting the development of a foetus. The aim of this study was to generate global gene expression profiles for the equine uterus during oestrus and dioestrus. To achieve this, samples were collected from 5 horses, once during oestrus (follicle > 35mm diameter) and once during dioestrus (5 days post ovulation), and analysed using high throughput RNA-Seq technologies. Genes identified as being differentially expressed between the two cycle stages were further investigated using Gene Ontology and KEGG pathway enrichment analyses. The expression levels of a total of 1577 genes were found to be significantly up-regulated during oestrus while 1864 genes were expressed at significantly higher levels in dioestrus. Most genes up-regulated during oestrus were associated with the extra-cellular matrix, signal interaction and transduction, cell communication or the immune function, whereas genes expressed at higher levels in dioestrus were most commonly associated with metabolic or transport functions. This correlates well with the physiological functions of the uterus – during oestrus it is expected to be preparing for potential infections facilitated by an open cervix and breeding, while the dioestrous uterus needs to be accommodating to a potential conceptus. These results allow for a more complete understanding of the hormonal influence on gene expression in the equine uterus and provide a valuable baseline for further research in equine reproduction, including analyses of changes associated with infection and inflammation.