Abstract
BackgroundIn mammals, an important source of genomic variation is insertion polymorphism of retrotransposons. These may acquire a functional role when inserted inside genes or in their proximity. The aim of this work was to carry out a genome wide analysis of ERE1 retrotransposons in the horse and to analyze insertion polymorphism in relation to evolution and function. The effect of an ERE1 insertion in the promoter of the myostatin gene, which is involved in muscle development, was also investigated.ResultsIn the horse population, the fraction of ERE1 polymorphic loci is related to the degree of similarity to their consensus sequence. Through the analysis of ERE1 conservation in seven equid species, we established that the level of identity to their consensus is indicative of evolutionary age of insertion. The position of ERE1s relative to genes suggests that some elements have acquired a functional role. Reporter gene assays showed that the ERE1 insertion within the horse myostatin promoter affects gene expression. The frequency of this variant promoter correlates with sport aptitude and racing performance.ConclusionsSequence conservation and insertion polymorphism of ERE1 elements are related to the time of their appearance in the horse lineage, therefore, ERE1s are a useful tool for evolutionary and population studies. Our results suggest that the ERE1 insertion at the myostatin locus has been unwittingly selected by breeders to obtain horses with specific racing abilities. Although a complex combination of environmental and genetic factors contributes to athletic performance, breeding schemes may take into account ERE1 insertion polymorphism at the myostatin promoter.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-015-0281-1) contains supplementary material, which is available to authorized users.
Highlights
In mammals, an important source of genomic variation is insertion polymorphism of retrotransposons
Since the frequency of insertion polymorphism of transposable elements is related to the age of their insertion in the host genome [11], these results strongly suggest that ERE1s are the elements that were inserted most recently in the horse genome
It must be underlined that, since the reference sequence derives from the genome of a single horse, the frequencies of polymorphic loci reported above are largely underestimated being based on the analysis of two alleles per locus
Summary
An important source of genomic variation is insertion polymorphism of retrotransposons. An inverse correlation between the evolutionary age of Alu subfamilies and the percentage of polymorphic elements was demonstrated: 20–25 % of the elements belonging to the youngest subfamily (AluY) are polymorphic [13] Because of their abundance and mechanism of origin, transposable elements were considered “junk DNA”, albeit, in a number of examples it was shown that they can acquire a functional role, a process termed “exaptation” [14,15,16,17]; in particular, the insertion of transposable elements inside genes or in their proximity may alter gene structure or expression through gene interruption, introduction of promoter sequences or splice sites [18,19,20]. Transposons are implicated in genetic disease or cancer [21,22,23]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
