Differentially methylated CpG sites in bull spermatozoa revealed by human DNA methylation arrays and bisulfite analysis

Abstract

The methylation status of sperm DNA differs between individual bulls. However, the relationship between methylation status and bull sperm parameters is not well elucidated. The present study investigated genome-wide methylation profiles at 450,000 CpG sites in bull spermatozoa by using a human DNA methylation microarray. Semen samples from three adult Japanese Black bulls with different in vitro fertilization (IVF) results and from a young Holstein bull through sexual maturation (at ages 10, 10.5, 15, and 25 months) were used for the analysis. The heatmap displaying the results of microarray analysis shows inter- and intra-individual differences in methylation profiles. After setting a cut-off of 0.2 for differences between ages (10, 10.5 vs. 15, 25 months) or between IVF results (developed to the blastocyst-stage, > 20% vs. < 10%), different methylation levels were detected at approximately 100 CpGs. We confirmed the different DNA methylation levels of CpG sites by using combined bisulfite restriction analysis (COBRA); five of the CpG sites reflected methylation levels similar to those detected by the microarray. One of the CpG sites was thought to reflect an age-related increase in methylation levels, which was confirmed by COBRA and bisulfite sequencing. However, the relationship between methylation status and IVF results could not be shown here. In conclusion, methylation profiles of individual and age-related alterations in bull spermatozoa can be revealed using a human microarray, and methylation changes in some CpG sites can be easily visualized using COBRA. Combined analysis of DNA methylation levels and sperm parameters could be considered an effective approach for assessing bull fertility in the future.

Parental Effects on Epigenetic Programming in Gametes and Embryos of Dairy Cows

“…Moreover, some of these DMR were mapped to genes that are transcriptionally active during preimplantation stages, suggesting their potential role in early embryo development ( Fang et al, 2019 ). Similarly, age-related DMRs were observed in bovine spermatozoa ( Takeda et al, 2017 , 2019 ; Lambert et al, 2018 ), and 57 of 2223 DMRs (2.56%) were retained in blastocysts ( Lambert et al, 2018 ; Wu et al, 2020 ). Among the genes that are mapped with these DMRs, some of them were involved in spermatogenesis (FKBP6) and embryonic preimplantation development (AKT2).…”

Sperm miR‐15a and miR‐29b are associated with bull fertility

“…Recently, a study showed that an increased expression of miR‐29b was associated with a decrease in DNMT 1 in adult rats, resulting in apoptosis and an elevated risk of infertility (Meunier et al, ). DNA methylation is an epigenetic control of gene expression in male fertility (Takeda et al, ), and DNA methyltransferases mediate the DNA methylation process by transferring a methyl group to genomic DNA sequence. In this study, the relative levels of DNMT1 were higher in spermatozoa from HF sires compared to those from LH bulls suggesting that spermatozoa of HF bulls maintain proper DNA methylation (Zhou et al, ).…”

DNA methylation in bull spermatozoa: evolutionary impacts, interindividual variability, and contribution to the embryo

“…In the mouse, sperm cells from elderly fathers display DNA methylation signatures of age in genes relevant to senescence, some of which are transmitted to the offspring and potentially contribute to their shorter lifespan and exacerbate aging-associated pathologies (Xie et al 2018). In the dairy industry, the use of semen collected from very young bulls enables both reduced rearing costs and increased genetic gain, but this practice is not without significance because intra-individual variations affecting DNA methylation in semen collected at different ages have recently been reported (Takeda et al 2017(Takeda et al , 2019Lambert et al 2018). In the earlier study (Takeda et al 2017), semen samples displaying contrasted quality parameters, and IVF Note: CR, conception rate; SQ, semen quality; IVF, in vitro fertilization; CPF, chlorpyrifos; PCR, polymerase chain reaction.…”