Abstract
BackgroundSperm DNA is protected against fragmentation by a high degree of chromatin packaging. It has been demonstrated that proper chromatin packaging is important for boar fertility outcome. However, little is known about the molecular mechanisms underlying differences in sperm DNA fragmentation. Knowledge of sequence variation influencing this sperm parameter could be beneficial in selecting the best artificial insemination (AI) boars for commercial production. The aim of this study was to identify genes differentially expressed in testis tissue of Norwegian Landrace and Duroc boars, with high and low sperm DNA fragmentation index (DFI), using transcriptome sequencing.ResultsAltogether, 308 and 374 genes were found to display significant differences in expression level between high and low DFI in Landrace and Duroc boars, respectively. Of these genes, 71 were differentially expressed in both breeds. Gene ontology analysis revealed that significant terms in common for the two breeds included extracellular matrix, extracellular region and calcium ion binding. Moreover, different metabolic processes were enriched in Landrace and Duroc, whereas immune response terms were common in Landrace only. Variant detection identified putative polymorphisms in some of the differentially expressed genes. Validation showed that predicted high impact variants in RAMP2, GIMAP6 and three uncharacterized genes are particularly interesting for sperm DNA fragmentation in boars.ConclusionsWe identified differentially expressed genes between groups of boars with high and low sperm DFI, and functional annotation of these genes point towards important biochemical pathways. Moreover, variant detection identified putative polymorphisms in the differentially expressed genes. Our results provide valuable insights into the molecular network underlying DFI in pigs.
Highlights
Sperm DNA is protected against fragmentation by a high degree of chromatin packaging
Differential expression A total of 308 genes in Landrace and 374 genes in Duroc were significantly differentially expressed in testis tissue from boars with high and low sperm DNA fragmentation index (DFI) [see Additional file 1 and Additional file 2 for Landrace and Duroc, respectively]
The results showed that high impact variants in the differentially expressed genes Receptor activity modifying protein 2 (RAMP2), GIMAP6, ENSSSCG00000000712, ENSSSCG00000009348 and ENSSSCG00000028326 are interesting for sperm DNA fragmentation in boars
Summary
Sperm DNA is protected against fragmentation by a high degree of chromatin packaging. Altered sperm chromatin structure is van Son et al BMC Veterinary Research (2017) 13:362 associated with DNA fragmentation and the degree of sperm DNA fragmentation is shown to be correlated to fertility in different species [4, 6,7,8,9,10,11,12,13] This parameter is a much more objective marker of sperm quality and function than standard subjective microscopic evaluations [14, 15]. The SCSA thereafter measures the relationship between double-stranded (i.e. condensed chromatin) and single-stranded (i.e. denatured) DNA for each sperm cell This relationship is quantified by the DNA Fragmentation Index (DFI) [12]. DFI is found to be an important parameter for predicting normal development of the embryo [11, 16] and is associated with abortion in humans [17]
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.
