Unraveling the role of sperm retained histones in bull fertility and daughter fertility

During spermatogenesis, a substantial proportion of histones are substituted by protamine to condense the genome within the sperm head. Studies indicate that a minority of histones, typically ranging from 1 to 15 %, persist in mammalian sperm post-substitution. The persistence of histones in the zygote facilitates chromatin accessibility to transcription factors in regions crucial for early embryonic development. Nevertheless, the potential causal relationship between retained histones and fertility phenotypes remains uncertain. This study seeks to investigate this relationship. The results indicate that in mature bovine sperm, regions of DNA associated with fertility that bind to histones are primarily concentrated in promoters and transcription start sites, potentially impacting bull fertility and offspring fertility through the regulation of relevant genes. Furthermore, microRNAs and estradiol/ESR are suggested to be the main regulators of the canonical pathways identified, highlighting the need for additional research to investigate their potential utility as biomarkers.